Research Library

S. Prabhavathi, Swapna M. Gali, Kiran Kumar Tadi et al.

Journal of The Electrochemical Society · 2025

Biofilms pose challenges such as infection transmission, biofouling, equipment failure, and environmental damage. Despite extensive research, their detection in bioenvironmental systems remains a significant challenge for researchers. Electrochemical impedance spectroscopy (EIS) stands out as an exceptionally sensitive and non-destructive technique for real-time monitoring of biofilms. In this study, we employed EIS to investigate the biofilm formation dynamics of the gram-positive bacterium Staphylococcus aureus ( S.aureus ) on indium-titanium oxide (ITO)-coated polyethylene terephthalate (PET) conductive substrates. Comprehensive characterization of both control and biofilm-coated substrates was carried out using. The temporal evolution of S.aureus biofilm growth was tracked through EIS measurements, revealing a substantial increase in charge transfer resistance as the biofilm matured. The extracellular electron transfer between the biofilm-coated electrode and the electrolyte was assessed by modulating the EIS bias potential at open circuit potential. Linear response in the charge transfer resistance with increased concentration of S.aureus was studied from 1.0 × 10 5 to 1.0 × 10 7 CFU ml −1 with a limit of detection of 3.5 × 10 4 . Overall, this work presents a simple yet highly sensitive biosensor for biofilm detection and growth analysis, eliminating the need for complex substrate modifications.

Πέτρος Σακκάς

· 2016

Για τη σύνθεση νανοσωματιδίων οξειδίων των μετάλλων και μετάλλων χρησιμοποιήθηκαν αντίστοιχα μέθοδοι ηχοχημείας και ηχοηλεκτροχημείας. Ταυτόχρονα, με τη δράση των υπερήχων, επιτεύχθηκε διακόσμηση (decoration) τεχνολογικώς ώριμων σκονών ανόδων κυψελών καυσίμων. Οι τροποποιημένες σκόνες μπορούν να χρησιμοποιηθούν στην πλευρά της ανόδου κυψελών στερεού οξειδίου και μεμβράνης εναλλαγής πρωτονίων. Στην περίπτωση της ηχοχημικής σύνθεσης, οργανομεταλλικές ενώσεις διαλελυμένες σε οργανικούς διαλύτες αποτέλεσαν τα πρόδρομα υλικά ενώ κατά την ηχοηλεκτροχημική σύνθεση, άλατα μετάλλων σε υδατικό διάλυμμα έδωσαν νανοσωματίδια μετάλλων με τη βοήθεια σταθεροποιητών οργανικής σύστασης.Οι νανοσχηματισμοί οξειδίων των μετάλλων που συντέθηκαν ήταν αυτοί του βολφραμίου, μολυβδαινίου και ρηνίου, ενώ τα νανοσωματίδια μετάλων που συντέθηκαν ήταν αυτά του χρυσού, του χαλκού και της πλατίνας. Κάθε είδος υλικού που προετοιμάστηκε, διακοσμήθηκε τελικώς επί σκόνης μηχανικού μίγματος οξειδίου του νικελίου και τροποποιημένης με γαδολίνιο δημητρίας. Εκτός αυτών, σωματίδια carbon black διακοσμήθηκαν με νανοσωματίδια πλατίνας. Το carbon black αποτελεί μια ενεργοποιημένη μορφή άνθρακα η οποία χρησιμοποιείται κατά κόρον σε μεμβράνες εναλλαγής πρωτονίων. Ως εκ τούτου, ένας από τους κυριότερους στόχους των τεχνικών διακόσμησης που αναπτύχθηκαν σε αυτή τη μελέτη ήταν ο έλεγχος της φόρτισης νανοσχηματισμών επί σωματιδίων σκόνης υποστρώματος. Την ίδια στιγμή, η μέθοδος διακόσμησης ήταν σημαντικό ν' αφήνει αρκετή εκτεθειμένη επιφάνεια διαθέσιμη ώστε να μπορούν να λειτουργούν ως αναμένται στην άνοδο μια κυψέλης καυσίμου.Η ηχοχημεία οφείλει τη δύναμή της στα κύματα υπερήχων τα οποία προκαλούνται εντός ενός υγρού μέσου. Τα κύματα αυτά δημιουργούν κατά τόπους στο υγρό απειροελάχιστες κοιλότητες, οι οποίες αυξομειώνονται περιοδικά με το χρόνο έως ότου φτάνουν σε ένα μέγεθος στο οποίο καταρρέουν. Κατά την κατάρρευση, όλες οι αέριες ουσίες οι οποίες καταλάμβαναν την κοιλότητα εξαναγκάζονται να συσσωρευθούν σε ένα απειροελάχιστο σημείο στο κέντρο της τέως ζώσας κοιλότητας. Σε αυτό ακριβώς το σημείο αναπτύσσονται ιδιαίτερα αυξημένες ποσότητες θερμοκρασίας και πίεσης, και μάλιστα μέσα σε ένα εξαιρετικά βραχύ χρονικό διάστημα. Κάτω από αυτές τις συνθήκες είναι πλέον δυνατόν να συντεθούν νανοϋλικά.Στην ηχοηλεκτροχημεία, εξ άλλου, χρησιμοποιείται η μέθοδος της ηλεκτροαπόθεσης ούτως ώστε να επιτραπεί η σύνθεση και ανάπτυξη σωματιδίων των μετάλων επί της ελεύθερης μεταλλικής επιφάνειας του ηλεκτροδίου εργασίας. Ακολούθως, αξιοποιείται η δράση του υπερήχου έτσι ώστε να επιτύχει την απόσχιση σωματιδίοων από το ηλεκτρόδιο. Με αυτό τον τρόπο λαμβάνει χώρα η σύνθεση και καθαρών μετάλλων νανομετρικής κλίμακας.Για τη σύνθεση νανοσωματιδίων οξειδίων των μετάλλων του βολφραμίου, του μολυβδαινίου και του ρηνίου χρησιμοποιήθηκαν αντίστοιχα οι πρόδρομες ουσίες W(CO)$_6$, Mo(CO)$_6$ και Re$_2$(CO)$_{10}$. Από την άλλη, τα πειράματα που σχεδιάστηκαν με στόχο τη σύνθεση νανοσωματιδίων μεταλλικού χρυσού, χαλκού και πλατίνας συμπεριλάμβαναν αντίστοιχα τις πρόδρομες ουσίες HAuCl$_{4}\cdot$3H$_2$O, CuSO$_{4}\cdot$5H$_2$O και PtCl$_{6}\cdot$H$_{2}$O. Στα υδατικά πρόδρομα διαλύματα πραγματοποιήθηκε επίσης ρύθμιση του pH με την προσθήκη των σχετικών αντιδραστηρίων. Σε κάθε περίπτωση προστέθηκε poly(N-vinyl-2-pyrrolidone) ως επιφανειοδραστική ουσία η οποία δρα ως ανασταλτικός παραγών ως προς την ανάπτυξη μεγάλων κρυσταλλικών δομών. Ως υλικά προς διακόσμηση χρησιμοποιήθηκαν NiO/GDC και carbon balck, τα οποία χρησιμοποιήθηκαν ακριβώς όπως αγοράσθηκαν από σχετικές εταιρίες σύνθεσης υλικών κυψελών καυσίμων.Τα πειράματα σύνθεσης οξειδίων των μετάλλων έδειξαν ότι η ένταση των υπερήχων όπως και το είδος του οργανικού διαλύτη που χρησιμοποιείται είναι σε θέση να επιδράσουν στην τελική διασπορά μεγέθους όπως επίσης και μορφολογία των δημιουργούμενων νανοσχηματισμών. Την ίδια στιγμή, ο λόγος βάρους πρόδρομης ουσίας και υποστρώματος όπως επίσης η ένταση και διάρκεια του υπερήχουβρέθηκαν να επηρεάζουν την έκταση της φόρτισης των νανοσχηματισμών επί του υποστρώματος. Ηλεκτρονική μικροσκοπία διερχόμενης δέσμης (TEM) χρησιμοποιήθηκε κυρίως για την αναγνώριση του τελικού προϊόντος όπως αυτό προέκυψε σε κάθε προσπάθεια σύνθεσης. Επιπροσθέτως, χαρακτηριστικές νανομορφολογίες εξετάσθκαν με σκεδασμό ηλεκτρονίων επί επιλεγμένων περιοχών (SAED) και έδωσαν σημαντικές πληροφορίες σχετικά με την νανοκρυσταλλικότητα και στοιχειομετρία όλων των υλικών που συντέθηκαν.Η πειραματική διαδικασία σύνθεσης νανοσωματιδίων των μετάλλων ακολούθησε μια αρχή παλμικής ηλεκτροαπόθεσης ακολουθούμενης από ένα βραχύ διάστημα δράσης υπερήχου. Ο κύκλος αυτός συνεχίστηκε έως ότου επιτευχθεί ένα σχετικά πυκνό κολλοείδες διάλυμα σωματιδίων μετάλλου, τα οποία θα διατηρούσαν το μέγεθός τους και διασπορά λόγω του επιφανειοδραστικού που χρησιμοποιήθηκε. Κολλοειδή διαλύματα ηχοβολήθηκαν κατόπιν μαζί με σκόνη υποστρώματος η οποία βρέθηκε σε αιώρηση. Απεδείχθη ότι τα νανοσωματίδια του κολλοειδούς διαλύματος μπορούν να δικοσμηθούν επί των σωματιδίων της σκόνης υποστρώματος. Στην περίπτωση της πλατίνας χρησιμοποιήθηκε μια άλλη προσέγγιση. Το carbon black βρέθηκε σε αιώρηση εντός του πρόδρομου διαλύματος με αποτέλεσμα κατά τη σύνθεση των νανοσωματιδίων πλατίνας να λάβει χώρα in-situ η διακόσμηση των σωματιδίων carbon black. Εκτός της μικροσκοπίας TEM, η χρήση της δυναμικής σκέδασης του φωτός (DLS) βοήθησε πολύ στο να καθοριστούν οι διάρκειες των επί μέρους παλμών.Όλες οι τιμές φόρτισης των διακοσμήσεων αποφασίσθηκαν με βάση τη βιβλιογραφία. Ο απότερος στόχος ήταν ο καθορισμός μεθόδου που θα μπορούσε να δώσει υλικό με κατάλληλες φορτίσεις έτσι ώστε το ίδιο να χρησιμοποιηθεί σε πειραματικές διατάξεις κυψελών καυσίμου. Επιπροσθέτως, οι διακοσμημένες σκόνες που προετοιμάσθηκαν κατά την παρούσα μελέτη εστάλησαν και δοκιμάστηκαν σε διάταξη θερμοκρασιακά προγραμματιζόμενης αναγωγής \& οξείδωσης (TPR \& TPO). Ως εκ τούτου τα υλικά που συντέθηακν απεδείχθη ότι μπορούν να ενισχύσουν τη διαδικασία υγρής αναμόρφωσης του μεθανίου, του κυριότερου συστατικού του φυσικού αερίου.

Eric Frantz, Andrew Steckl

ECS Meeting Abstracts · 2020

Bacteria are one of the most common sources of illness, responsible for a wide range of infections. Bacterial infections can be caused from a variety of sources, with thousands of deaths attributed to waterborne outbreaks alone [ 1 ]. Detection of both infectious and non-infectious bacteria is utilized to ensure commercial goods and water are safe for consumers. Current detection of bacterial contamination typically uses cell culture plates to measure the number of colony forming bacteria (CFU/ml) in a liquid media. This technique is widely used due to its high sensitivity and easy visual readout. Unfortunately, culture counting techniques is time consuming (1-3 days), requires skilled lab technicians, can be contaminated during preparation, and cannot be integrated into the desired testing media directly. To overcome these limitations, many bacterial sensors and detection techniques have been developed over the last few decades [ 2 ]. A recent sensor for bacteria detection is the organic electrochemical transistor (OECT). OECTs are polymer-based transistors that utilize ionic solutions to de-dope and re-dope a conducting channel. These devices are known for their high transconductance, bio-compatibility, low operating voltage, low cost, small size, ease of integration into measurement systems, and ability to function in aqueous environments [ 3 ]. Detection of a single bacteria is typically desired and achieved through the capture of bacteria cells onto the OECT channel area [ 4 ]. This approach allows for rapid detection of a specific pathogen with high sensitivity. However, for detecting contamination from a variety of bacteria a different approach must be used. We have investigated the OECT response to the presence of non-captured bacteria present within the OECT operating media. In this approach cells are detected both in solution and on the surface of the source-drain channel and on the gate electrode. Presence of bacteria between the gate and channel region will cause an increase in effective gate voltage, resulting in a decrease in source-drain current. Detection and characterization of (non-bacteria) whole cells has previously been reported utilizing this approach [ 5 , 6 ]. In our work we have focused on the bacteria pseudomonas fluorescens (p. fluorescens) due to its size (~1µm) and potential as a water borne pathogen. P. fluorescens was cultured in LB media, diluted to three different concentrations, and used as the operating media for OECT. Concentrations of 8.7e12, 8.7e11, and 8.7e10 CFU/ml were found to shift source-drain current by 16.1, 13.8, and 12.3µA, respectively. From this data a present lower limit of detection for the sensor is estimated to be ~5.0e4 CFU/ml. 1. Craun, G.F., Statistics of waterborne outbreaks in the US (1920–1980). Waterborne diseases in the United States, 2018: p. 73-159. 2. Ahmed, A., et al., Biosensors for whole-cell bacterial detection. Clinical microbiology reviews, 2014. 27(3): p. 631-646. 3. Strakosas, X., M. Bongo, and R.M. Owens, The organic electrochemical transistor for biological applications. Journal of Applied Polymer Science, 2015. 132(15). 4. Demuru, S., et al. Flexible Organic Electrochemical Transistor with Functionalized Inkjet-Printed Gold Gate for Bacteria Sensing. in 2019 20th International Conference on Solid-State Sensors, Actuators and Microsystems & Eurosensors XXXIII (TRANSDUCERS & EUROSENSORS XXXIII). 2019. IEEE. 5. Liao, J., et al., Organic electrochemical transistor based biosensor for detecting marine diatoms in seawater medium. Sensors and Actuators B: Chemical, 2014. 203: p. 677-682. 6. Ramuz, M., et al., Monitoring of cell layer coverage and differentiation with the organic electrochemical transistor. Journal of Materials Chemistry B, 2015. 3(29): p. 5971-5977. Figure 1

Donald R. Demuth, Donald R. Demuth, Donald R. Demuth et al.

Cambridge University Press eBooks · 2006

Many bacterial diseases are caused by organisms growing together as communities or biofilms. These microorganisms have the capacity to coordinately regulate specific sets of genes by sensing and communicating amongst themselves utilizing a variety of signals. This book examines the mechanisms of quorum sensing and cell-to-cell communication in bacteria and the roles that these processes play in regulating virulence, bacterial interactions with host tissues, and microbial development. Recent studies suggest that microbial cell-to-cell communication plays an important role in the pathogenesis of a variety of disease processes. Furthermore, some bacterial signal molecules may possess immunomodulatory activity. Thus, understanding the mechanisms and outcomes of bacterial cell-to-cell communication has important implications for appreciating host-pathogen interactions and ultimately may provide new targets for antimicrobial therapies that block or interfere with these communication networks.

Yang Xu

· 2024

Although there has been significant progress in the understanding of the mechanism and regulation of bacterial cell envelope biogenesis, further exploration is required to fully understand the bacterial cell envelope and its synthesis machineries and develop new methods to kill bacteria. This thesis aims to showcase the fluorescent labeling methods for studying bacterial cell wall envelopes and their application in studying outer membrane (OM) permeability and killing antibiotic-resistant pathogens. The assays involve chemical and chemoenzymatic synthesis, advanced microscopy techniques, and microorganism assays, and expand the toolbox of labeling bacteria and make it more accessible to a wider range of researchers. Chapter 2 describes a fluorescent labeling method that can label the newly synthesized lipopolysaccharides (LPS) of Gram-negative bacteria using azido-galactose, which is a common monosaccharide in bacterial LPS. This method provides a new way to specifically label Gram-negative bacteria through a click-chemistry reaction. Chapter 3 outlines a labeling strategy for peptidoglycan (PG) by functionalizing GlcNAc. This one-step biosynthesis of UDP-GlcNAz serves as an intermediate for incorporation into PG, allowing for labeling of the glycan core of PG. This approach provides a complementary labeling strategy for bacterial labeling that targets a different component than the previous study. The study is published in iScience in 2022. Chapter 4 describes the photodynamic inactivation of antibiotic-resistant pathogens using chemical photosensitizers, including photoactive D-amino acid derivatives and antibiotic photosensitizers. The killing mechanisms involve the incorporation of D-amino acids, penicillin-binding protein (PBP) binding, and D-ala-D-ala binding, leading to membrane damage and efficient killing of MRSA and VISA. Chapter 5 investigates OM permeability through a designed approach of labeling peptidoglycan with trans-cyclooctenes (TCO) and using fluorogenic probes to indicate OM permeability through the strain-promoted inverse electron-demanding Diels-Alder cycloaddition (SPIEDAC) reaction. This provides a direct method to indicate OM permeability. In summary, this thesis showcases new and complementary fluorescent labeling methods for bacterial components and their applications in studying OM permeability and killing antibiotic-resistant pathogens. These methods expand the toolbox of labeling bacteria and provide useful tools for researchers to study bacterial cell envelope biogenesis.

Wenfa Ng

· 2017

Bacteria surface charge mediates important cell-environment and microbe-host interactions, and its accurate and precise measurement by microelectrophoresis requires removing metabolites adhered to the cell surface, where repeated centrifugation and washing by buffers is the gold standard method for sample preparation. Unfortunately, the need for time consuming centrifugation limits the temporal resolution of sampling and profiling of experiment system dynamics; especially for samples requiring immediate treatment after sampling. Herein, the feasibility of diluting cell aliquots with buffer as a single step sample preparation technique for surface charge measurement was investigated by characterizing the effects of dilution ratio, cation type, and buffer conductivity on measuring surface charge of Escherichia coli DH5α (ATCC 53868) grown in LB Lennox medium. Results indicated that dilution ratio was critical to accurate surface charge measurement since poor signal-to-noise ratio in high or low cell concentration samples generated substantial error. Type of buffer cation was also important since putative binding of high affinity cations to the negatively-charged cell surface underestimated surface charge. Finally, high conductivity buffers enabled greater removal of adsorbed metabolites through increased charge screening; however, a broader statistical distribution of measured surface charge and less accurate data were also observed. At extreme conductivity values, measured surface charge exhibited multi-modal distribution; due probably to removal of both intrinsic cell surface ions and exogenous adsorbed metabolites, and called into question the accuracy of data. Altogether, one step dilution of cell aliquot with deionized water reliably reproduced E. coli surface charge values obtained using the gold standard approach. But, since the ensemble of secreted metabolites is bacteria and medium specific, distinct diluent and experimental parameters exist for each system. The described methodology may find use in preparing samples for cell surface characterization studies, where it would help reduce sample preparation time, and thus, improve temporal resolution at which scientific questions can be probed and answered.

Nikola Ojkic, Shiladitya Banerjee

bioRxiv (Cold Spring Harbor Laboratory) · 2021

ABSTRACT By analysing cell shape and size of the bacterium Bacillus subtilis under nutrient perturbations, protein depletion, and antibiotic treatments we find that cell geometry is extremely robust, reflected in a well-conserved scaling relation between surface area ( S ) and volume ( V ), S ~ V γ , with γ = 0.85. We develop a molecular model supported by single-cell simulations to predict that the surface-to-volume scaling exponent γ is regulated by nutrient-dependent production of metabolic enzymes that act as cell division inhibitors in bacteria. Using theory that is supported by experimental data, we predict the modes of cell shape transformations in different bacterial species and propose a mechanism of cell shape adaptation to different nutrient perturbations. For organisms with high surface-to-volume scaling exponent γ , such as B. subtilis , cell width is not sensitive to growth rate changes, whereas organisms with low γ , such as A. baumannii , cell shape adapts readily to growth rate changes. SIGNIFICANCE How bacteria regulate their size and shapes to optimise their growth fitness in different nutrient environments remains largely unknown. By analysing the surface area and volume of rod-shaped B. subtilis exposed to different nutrient conditions and antibiotics we find that cells preserve a power law scaling between surface area and volume. We show that the surface-to-volume scaling is extremely robust and is regulated by nutrient-dependent synthesis of cell division inhibitors. By analysing different bacterial types, we find that cells conserve the surface-to-volume scaling exponent that is typical for each species, implying distinct mechanisms for morphological adaptation in each organism.

Aida Ebrahimi

ECS Meeting Abstracts · 2022

Traditional methods for bacterial detection and analysis are time consuming, labor-demanding, and have limited portability. This presents a significant opportunity for biosensor engineers to develop low-cost devices for bacterial studies. In this talk, I will discuss our recent advances in developing electrochemical biosensing devices for bacterial analysis. The devices enable characterizing cell envelope, metabolic activity, and quorum sensing molecules, and can provide real-time insight into bacterial response to environmental stress, such as drugs. The sensors feature functional materials to achieve specificity and sensitivity for analysis of real samples. Depending on the need, the biosensors are manufactured using a combination of different device fabrication methods, including standard microfabrication, electrodeposition, printing, and laser engraving of plastic and paper. Specifically, owing to compatibility with additive manufacturing and having rich active sites for functionalization, direct laser engraving enables rapid prototyping of low-cost sensors for a wide range of stand-alone diagnostic platforms.

Hiroshi Shiigi

ECS Meeting Abstracts · 2024

A better understanding of the biological functions of microorganisms is required to reduce their threats and increase their usefulness. Therefore, the importance of real-time evaluation of bacterial activity increases for various purposes such as hygiene management, development of antibacterial agents, and effective utilization of bacterial resources. 1 This necessitates a quantitative assessment of metabolic processes, including growth and respiration. Here we would like to introduce the development of electrochemical methods for assessing bacterial activity. Electrochemical detection of viable bacterial cells was performed using cell membrane permeable electron mediator and redox-active pigment. On the other hand, a tetrazolium salt (MTT), was converted to an insoluble reduction form (formazan) through the respiration of microbial cells. 2 The insolubility of this formazan was effectively exploited as a surface-confined redox event. The electrochemical detection of formazan was effectively coupled with the thermal lysis of microbes. The sensitivity of the present technique is up to 10,000-fold higher than that of MTT colorimetry and requires an incubation time of only 1 h, which is approximately 1/4 of that required for other metabolism-based techniques. On the other hand, Considering that oxidized MTT, which has excellent cell membrane permeability, changes into insoluble reduced formazan within cells, it is also possible to estimate the number of viable cells by focusing on the reduction current of MTT remaining in the suspension. was. Dissolved oxygen is an important substance for bacterial activity. When live bacteria in suspension were observed in real-time, it was found that uptake of MTT into bacteria was completed within 10 minutes, including the lag period. Furthermore, we also observed that the current response was dependent on viable cell density, regardless of the bacterial species present. This method allows us to quickly estimate the number of viable bacteria, making it possible to confirm the safety of food before it leaves the factory and prevent food poisoning. 3 Furthermore, the measurement of the reduction current of dissolved oxygen provides an effective means for assessing the respiratory activity of bacteria in suspension. 4 Organometallic nanohybrids (NHs), in which many small metal nanoparticles are encapsulated within a conductive polymer matrix, are useful as sensitive electrochemical labels because their components produce characteristic oxidation current responses. NHs made of metal nanoparticles such as gold or copper and polyaniline did not interfere with each other in terms of electrochemical signals obtained on the same electrode. Antibodies were introduced into these NHs that served as electrochemical labels to target specific bacteria. Electrochemical measurements using screen-printed electrodes dry-fixed with NH-labeled bacterial cells allowed the bacterial species and number to be estimated within minutes based on the distinct current response of the label. Our proposed method achieved simultaneous detection of enterohemorrhagic E. coli and Staphylococcus aureus in real samples. These NHs are expected to be a powerful tool as electrochemical labels and useful for rapid testing at food and pharmaceutical manufacturing sites. 5 1) T. Kinoshita, K. Ishiki, D. Q. Nguyen, H. Shiigi, T. Nagaoka, Anal. Chem. , 90 , 4098 (2018). 2) K. Ishiki, D. Q. Nguyen, A. Morishita, H. Shiigi, T. Nagaoka, Anal. Chem. , 90 , 10903 (2018). 3) H. Ikeda, A. Tokonami, S. Nishii, X. Shan, Y. Yamamoto, Y. Sadanaga, Z. Chen, and H. Shiigi, Anal. Chem. , 95 , 12358-12364 (2023). 4) M. Saito, K. Ishiki, D. Q. Nguyen, H. Shiigi, Anal. Chem. , 91 , 12793-12798 (2019). 5) S. Itagaki, A. Nakao, S. Nakamura, M. Fujita, S. Nishii, Y. Yamamoto, Y. Sadanaga, H. Shiigi, Anal. Chem. , 96 , 3787-3793 (2024).

So Tanabe, Shuyi Sun, Satohiro Itagaki et al.

· 2020

For the efficient utilization of bacterial bioresources, the quantitative evaluation of metabolic activity in live bacterial cells is required. Using potentiometric measurements, we quantitatively evaluated the electron generation rate of Shewanella oneidensis MR-1 based on individual enzymatic reactions. We evaluated intracellular electron generation in bacterial suspensions supplemented with different carbon sources utilized in the tricarboxylic acid cycle. In bacterial suspensions, ferricyanide was almost completely reduced to ferrocyanide by cell-generated electrons, without an effect on bacterial cell viability. Focusing on this reduction reaction, quantitative evaluations were possible by potentiometry based on the Nernst equation.

Hikaru Ikeda, Akira Tokonami, Hayato Fujimura et al.

ECS Meeting Abstracts · 2024

【Introduction】 Bacterial activity is an essential evaluation index for hygiene management and quality control of medicine and food because some bacteria such as Escherichia coli , Salmonella enterica , and Staphylococcus aureus are causative organisms that cause food poisoning and adversely affect the human body. Conventional bacterial testing has widely used methods that count colonies formed based on cell proliferation in culture. When the mother cell divides to produce her two daughter cells, the surviving cells multiply logarithmically. Most bacteria divide at least once within an hour, but some species take longer than 20 hours to divide, so visual confirmation of bacterial colonization may take at least 48 hours, and in some cases about 2 weeks. Hence, although this method reflects viability with accurate cell counts, it requires a long inspection time. A rapid and simple technique for bacterial detection based on dissolved oxygen, enzymatic reactions, and electron mediators was developed to circumvent this problem. This study focused on the electrochemical properties of tetrazolium salts to develop a simple method for evaluating viable bacterial counts, which are indicators of hygiene control at food and pharmaceutical manufacturing sites [1]. Given that the oxidized form of 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), which has excellent cell membrane permeability, changes to the insoluble reduced form of formazan inside the cells. The number of viable cells was estimated by focusing on the reduction current of MTT remaining in the suspension. Dissolved oxygen is an important substance for bacterial activity; however, it interferes with the electrochemical response of MTT. We investigated the electrochemical properties of MTT to obtain a potential-selective current response that was not affected by dissolved oxygen. Real-time observation of viable bacteria in suspension revealed that uptake of MTT into bacteria was completed within 10 min. In addition, we observed that the current response depends on viable cell density regardless of the bacterial species present. Our method enables a rapid estimation of the number of viable bacteria, making it possible to confirm the safety of food products before they are shipped from the factory and thereby prevent food poisoning. 【Experimental】MTT solution and 0.20% glucose-added nutrient broth medium were mixed and diluted with electrolytes, such as 0.10 M KCl aqueous solution and 0.10 M phosphate-buffered saline (PBS) solution (pH 7.4), to obtain 0.10 mM MTT solution. E. coli suspension (2.0 × 10 9 CFU mL － 1 ) was dropped into 0.10 mM MTT solution and incubated at 310 K for 1 h. Cyclic voltammetry (CV) was performed to measure MTT remaining in the suspension before and after incubation at a sweep rate of 0.10 Vs － 1 using a glassy carbon-disk electrode as the working electrode, a platinum coil as the counter electrode, and Ag|AgCl (3 M KCl) as the reference electrode. 【Results】Two sharp reduction peaks were observed at －0.1 V ( II c ) and －0.6 V ( I c ) at performing a cathode sweep from +0.2 V (Fig.1). These current responses are based on the reactions shown in the following equations. MTT + e － ⇄ MTT ・ （intermediate） [1] MTT ・ + H + + e － ⇄ formazan [2] The MTT-based current responses remaining in these electrolytes gradually decreased with incubation time and almost disappeared after 60 min of incubation. This means that MTT was taken up into cells and the generated insoluble formazan was deposited inside the cells. Although dissolved oxygen is certainly an important substance for bacterial activity, it can interfere with the electrochemical response of MTT. The current response of formazan formation ( I c ) was significantly different in the presence of dissolved oxygen (12%). However, the current response based on the intermediate formation reaction ( II c ) was unaffected (0%). Quantification of viable bacterial counts based on the current response of II c (10 3 –10 7 CFU mL － 1 ) was achieved by measuring the amount of residual MTT in the electrolyte. Furthermore, the current response was confirmed to be dependent on viable cell density, independent of bacterial wall structure and metabolic processes. 【Reference】 [1] H. Ikeda, A. Tokonami, S. Nishii, Y. Yamamoto, X. Shan, Y. Sadanaga, H. Shiigi, Anal. Chem. , 95 (33), 12358-12364 (2023). 【Images】 Fig.1 CVs of 0.10 mM MTT in 0.10 M PBS solution (pH 7.4) containing E. coli (2.0×10 9 CFU mL −1 ) during incubation at 310 K. Figure 1

Yongqiang Yang

· 2020

Even though rapid detection of molecular methods has been used in bacterial detection, (automated) liquid culture methods are still the "Gold Standard" for the detection of living bacteria, especially in cases where there may be similar dead bacteria also present in the sample. However, the current liquid culture methods rely on the effects of bacterial metabolism (changes in O2/CO2 levels, pH, etc.) to bring about measurable changes to the suspension. Hence, for slow-growing microorganisms like M. tuberculosis (Mtb), they take a long time (up to 6 weeks) to yield results. To cut the time to positivity, we applied the detection concept of "detection by death" and using our high sensitivity microchannel Electrical Impedance Spectroscopy (m-EIS) method to detect bacteria in various samples rapidly. Viable bacterial cells can be killed in a few hours with very high doses of cidal drugs. m-EIS relies on the fact that high-frequency AC fields cause transient charge-accumulation at live cells' intact membranes. Cell-death in the microchannel causes charges to no-longer be accumulated, and the bulk capacitance of the microchannel will decrease. By picking up this change, we can rapidly detect viable bacterial cells in a testing sample. For viable TB bacteria detection, we use synthetic sputum with gram-positive bacteria, gram-negative bacteria, and M. tuberculosis H37ra. After decontamination (kill all non-TB bacteria), we are able to discern decreases in bulk-capacitance for suspensions containing ~500 CFU/ml of Mtb cells (but not for ~50 CFU/ml). Thus, our turnaround-time (~4 hours) and limit-of-detection ([less than]500 CFU/ml) are comparable to those of GeneXpertTM. Using our m-EIS method, we can also detect Lactic Acid Bacterial (LAB) contamination for ethanol fermentation with a low concentration of 5000 CFU/ml in less than 3 hours. Our detection of limit for LAB has a three-order reduction than the HPLC method, but with a similar detection time. Aside from investigating the bacterial activities in the solution, we also observed the biofilm formation on the electrodes. We have observed that the interfacial capacitance also increases in proportion to the number of cells in the biofilm matrixes. In the future, we believe that we could also record cell death within biofilm using our method, and so researchers will be able to use it to screen new anti-biofilm material and drug rapidly.

Chia-Hung Hou, Chih-Yu Ma

ECS Meeting Abstracts · 2017

Due to unstainable use of natural water resources, alternative water resources such as brackish water and seawater desalination have been an emerging solution. However, development of desalination capacity is limited due to the high energy requirements for removing salt ions from water. Currently, capacitive deionization technology (CDI), following the working principle of supercapacitors, has attracted considerable attention from academia, industry, and government agency. As compared to conventional desalination technologies, CDI has several advantages including low energy consumption, easy regeneration, high water recovery, and no secondary waste. In CDI, by applying an external electric filed between two parallel of nanoporous carbon electrodes (i.e., carbon aerogel, activated carbons, carbon nanotubes, and graphene), ions can be stored at the electrode/solution interface via electrical double layer (EDL) formation. Additionally, microbial desalination cell (MDC) is a new bioelectrochemical technology for seawater desalination with simultaneous electricity generation and wastewater treatment. Basically, a MDC reactor contains an anode chamber, a desalination chamber, and a cathode chamber. In MDC, microorganisms can oxidize organic waters in wastewater to harvest electric energy, and meanwhile, salt ions can be removed during the electricity generating process. In this study, we propose a hybrid electrochemical desalination system for seawater desalination by coupling CDI device with a MDC reactor. As a result, MDC produced electricity with open circuit voltage of 0.8 V and a current of 3 mA by using bacteria to degrade organic contaminants through anode bacterial oxidation and cathode reduction. In MDC, 91% removal of chemical oxygen demand (COD) in synthetic wastewater can be achieved, and the solution conductivity can be reduced from 17,000 µS/cm to about 200 µS/cm. More importantly, CDI device can be driven by electricity harvesting from the two MDCs in parallel, and as the downstream desalination process to further desalinate salt water. The results of this study can demonstrate the feasibility of the integrated electrochemical MDC-CDI system for simultaneous wastewater treatment, power production, and water desalination. .

Wesley R. Browne

Electrochemistry · 2018

This chapter focuses on the electrochemical cell. It discusses electrode polarization in terms of the relationship between electrochemical cells and capacitors. The chapter also lists classifications of electrodes. These vary between the first, second, or third. It explores the process of achieving Galvanic (voltaic) cells. Next, the chapter cites how half-cell reactions are presented as being reduced by convention. The chapter also looks into the potential of a half-cell. It also presents the Nernst equations which relate the potential of a cell or half-cell to the actual concentration of the present species and standard reduction potential. The chapter then notes redox chemistry by referencing Latimer diagrams, Frost diagrams, Pourbaix diagrams, and Ellingham diagrams.

Yang Bae Jeon, Fusheng Tang, Jin Wook Lee

ECS Meeting Abstracts · 2015

Microbial biofuel cells produce electricity directly from organic fuels such as glucose sucrose, acetates and ethanol. In the present work, electrochemical characteristics of the yeast-catalyzed half cell against carbon cloth electrode with various yeasts and with immobilization are investigated experimentally. Three types of yeasts as anode catalyst are employed: (1) commercially available baker’s yeast (S. Cerevisiae); (2) wild type yeast cultured in our lab; and (3) respiration-free mutant yeast. Kinetic parameters for the three types of yeasts are obtained by Tafel analysis. Cyclic voltammetry (CV) techniques are applied to investigate the reversibility of the redox reactions. Open current potential (OCP) of each yeast is measured against a reference electrode to estimate the anodic potential. Electrochemical impedance spectroscopy (EIS) of the half-cell is conducted to estimate the resistivity of the electrode and the overall ohmic resistance. This fundamental kinetic study will be used to understand the activity of the yeast as a catalyst in microbial half cell as well as fuel cell.

KeeSuk Nahm, Pil KIM

ECS Meeting Abstracts · 2014

Microbial fuel cells (MFCs) is one of the promising green energy sources to produce electricity from organic wastes with the help of bacteria as catalyst. It converts the chemical energy in organic wastes into electricity by bioelectrochemical reactions. In spite of the promise of MFCs, their applications are limited by low power generation efficiency. Power limitations can be addressed by the use of better suited anodes, and to modify the electrode surface with nanostructures is one of the ways to improve the efficiency of the anode. In this study, We have demonstrated MFCs performance based on Escherichia coli (E.coli) by optimizing the electrode surface structure using various nanomaterials like reduced grapheme oxide(rGO), graphite nanofiber(GNF) and carbon nanotube(CNT). Each of the nanomaterials is doped with iron particles of 3~10nm size, and were formed into a nanocomposite. The synthesized nanocomposites was assembled on the anode electrode surface by directly applying a magnetic field. This conductive multilayer of nanocomposites coated on anode enhances the electron transfer between the bacteria and the anode. The electrochemical activities with each catalysts of such as Fe/rGO, Fe/GNF and Fe/CNT are investigated by cyclic voltammetry, Impedance spectra and polarization curve measurements.

Léna Beauzamy, Jérôme Delacotte, Benjamin Bailleul et al.

bioRxiv (Cold Spring Harbor Laboratory) · 2020

ABSTRACT Microbial solar cells that mainly rely on the use of photosynthesic organisms are a promising alternative to photovoltaics for solar electricity production. In that way, we propose a new approach involving electrochemistry and fluorescence techniques. The coupled set-up Electro-Pulse-Amplitude-Modulation (“e-PAM”) enables the simultaneous recording of the produced photocurrent and fluorescence signals from the photosynthetic chain. This methodology was validated with a suspension of green alga Chlamydomonas reinhardtii in interaction with an exogenous redox mediatior (2,6-dichlorobenzoquinone; DCBQ). The balance between photosynthetic chain events (PSII photochemical yield, quenching) and the extracted electricity can be monitored overtime. More particularly, the non photochemical quenching induced by DCBQ mirrors the photocurrent. This set-up thus helps to distinguish the electron harvesting from some side effects due to quinones in real time. It therefore paves the way for future analyses devoted to the choice of the experimental conditions (redox mediator, photosynthetic organisms…) to find the best electron extraction.

M. Mawardi, W. S. Winanti, T. Sudinda et al.

IOP Conference Series: Earth and Environmental Science · 2023

The issue of global warming continues to be a concern for the international world. One of the causes of global warming is the greenhouse gas (GHG) effect caused by an increase in the amount of emissions in the atmosphere. Indonesia has set targets for reducing GHG emissions in the Nationally Determined Contribution (NDC) by 31.89% on its own capability and 43.20% with international assistance in 2030. Therefore, to support the program, it is necessary to conduct research to inventory the emissions produced and emissions absorbed by each region in Indonesia. This study calculated the net-zero emission index in an area by comparing the value of carbon emission with the value of carbon sequestration based on land cover in an area. Regional emission data was obtained from Aksara Bappenas, while regional sequestration data was obtained from RAD-GRK and satellite imagery interpretation based on land cover. Meanwhile, to calculate emissions at the city/regency level, individual carbon footprint data was used and converted into city/regency emission data. The calculation of the carbon index was carried out nationally in all provinces of Indonesia. Several provinces were further tested as examples to determine sequestration based on land cover from imagery interpretation. The results show that the Indonesian net-zero emission index is lower than 1, but some provinces with dense populations have a net-zero emission index >1, namely: DKI Jakarta, DI Yogyakarta, North Sumatra, and Riau.

A. Khan, Lizhen Huang

Energies · 2023

Due to an extensive usage of heavy machinery, the construction sector is criticized as one of the major CO2 emitters. To address climate concerns, mitigating these greenhouse gas (GHG) emissions is important. This study aimed to strategize for “zero emission construction” by assessing the life cycle environmental impacts of diesel, electric, and hybrid construction machinery. By applying life cycle assessment (LCA) principles with adherence to ISO 14040/44 methodologies, this study scrutinizes the environmental repercussions of a standard excavator over 9200 effective operational hours, from raw material acquisition to end-of-life disposal. The results demonstrate a significant reduction in global warming potential (GWP), ozone depletion potential (ODP), and acidification potential (AP) in transitioning from diesel to hybrid and fully electric machines. A nominal increase due to this shift also occurred and impacted categories such as human carcinogenic toxicity (HT), freshwater eutrophication (EP), and marine ecotoxicity (ME); however, a more significant upsurge was noted in terrestrial ecotoxicity (TE) due to battery production. Thus, this study highlights the need for a careful management of environmental trade-offs in the shift toward electrified machinery and the importance of centering on the environmental profile of the battery. Future work should focus on enhancing the environmental profile of battery production and disposal, with policy decisions encouraging holistic sustainability based on green energies in construction projects.

Qiao Yu, Brian Yueshuai He, Jiaqi Ma et al.

Nature Communications · 2023

Zero-emission vehicle (ZEV) adoption is a key climate mitigation tool, but its environmental justice implications remain unclear. Here, we quantify ZEV adoption at the census tract level in California from 2015 to 2020 and project it to 2035 when all new passenger vehicles sold are expected to be ZEVs. We then apply an integrated traffic model together with a dispersion model to simulate air quality changes near roads in the Greater Los Angeles. We found that per capita ZEV ownership in non-disadvantaged communities (non-DACs) as defined by the state of California is 3.8 times of that in DACs. Racial and ethnic minorities owned fewer ZEVs regardless of DAC designation. While DAC residents receive 40% more pollutant reduction than non-DACs due to intercommunity ZEV trips in 2020, they remain disproportionately exposed to higher levels of traffic-related air pollution. With more ZEVs in 2035, the exposure disparity narrows. However, to further reduce disparities, the focus must include trucks, emphasizing the need for targeted ZEV policies that address persistent pollution burdens among DAC and racial and ethnic minority residents.

Harshad Jathot

International Journal for Research in Applied Science and Engineering Technology · 2024

Abstract: With the rapid growth of digital services and the increasing reliance on data centers, energy consumption and carbon emissions from server infrastructure have become significant environmental concerns. This abstract outlines a novel approach for carbon detection from servers, aiming to improve the sustainability of data centers. Carbon emissions from data centers are increasingly a cause for concern, as the world grapples with the realities of climate change. According to recent studies, data centers are responsible for a significant share of global electricity consumption, and subsequently, carbon emissions. It’s evident that addressing the sustainability of data centers is not just a technological challenge; it’s a moral and environmental imperative.

Patrick Fortin

ECS Meeting Abstracts · 2022

The overall aim of this project is to establish a generic modelling platform for the design and operation of zero-emission MW-scale hybrid electric energy systems, with a particular focus on maritime transport applications. The project seeks to integrate battery and fuel cell degradation models with operating strategy models to minimize the total cost of ownership (TCO) of hybrid battery/fuel cell systems. The modelling approach used here, to simulate battery and fuel cell degradation, takes advantage of empirical modelling methods already established in the scientific literature. This approach offers three distinct advantages over alternative multi-physics models, in that empirical degradation models are (i) computationally efficient, (ii) can be integrated into other modelling frameworks, and (iii) can support the quick parameterization of different systems. Real-life battery and fuel cell degradation data, collected using state-of-the-art materials, was used to quantify the model parameters and validate the proposed degradation models. A variety of advanced in-situ electrochemical characterization methods have been employed to quantify the relevant parameters at the beginning-of-life and again after various stages of ageing to determine degradation rates of the relevant parameters. The second aspect of this project is the implementation of a technoeconomic optimization model that combines the data-driven degradation models with additional inputs such as operating conditions, operational profile (i.e., drive cycle), cost of hydrogen, cost of electricity, etc. to design optimal hybrid battery/fuel cell systems and determine optimal control strategies to minimize degradation and total cost of ownership over the system lifetime. This talk will focus on the advanced in-situ electrochemical techniques that have been used to extract fuel cell degradation parameters and provide an overview of both the empirical degradation and technoeconomical models. Finally, we will present the optimization results obtained using our platform for the implementation of a hybrid energy system in a coastal Norwegian ferry.

Jing-yu Ran, Chang-lei Qin

ASME 2010 Power Conference · 2010

CO2 is a main greenhouse gas fazing the Earth. So countries around the world are actively studying the methods of capturing CO2 to reduce emission. In this paper, firstly a brief review was carried out on the research development and technical problems of three typical near-zero CO2 emission power generation systems. Focus was made on the construction of one possible commercially applied zero emission system, which has new principle but relatively conservative sections. Preliminary analysis and calculation of energy and mass flow have been finished to evaluate its performance. The results showed that apart from zero CO2 emission, a relatively tempting efficiency could be sustained. Theoretically, higher than 90% purity of CO2 and 63% generation efficiency of the whole system can be achieved.

Mahboob Mian, Nawal Al Qubaisi

Abu Dhabi International Petroleum Conference and Exhibition · 2012

Abstract Gas Processing Facility (GPF) project achieved Zero flaring 1.7million standard cubic feet per day (41.65 tons) gas recovered thru Vapor Recovery System and protect the environment by reducing; CO2: 3,924 tons/yr CO: 123.6 tons/yr NOx: 21.6 tons/yrs ➢ Total gas recovered: 612 million standard cubic feet per year ➢ Revenue saving: 835,380 US$ /year Vapor Recovery Unit (VRU): Under this unit, gases from the Tertiary Ethyl Glycol (TEG)Dehydration package and vents from compressors dry gas seals are recovered/ captured and compressed in the VRU and then sent to the suction for the main gas compressor for reuse instead of going to flare Gas Processing Project (GPF) at Zakum complex is a new gas treatment platform that will augment the existing gas processing capacity of the Zakum West Super Complex. It will increase the associated gas production from Zakum oilfield. The beauty of this project is that ADMA has employed the Zero flaring policy. There will be no flaring at all at this platform. This is one of the unique project of its nature in the ADNOC group of companies, even in Emirates and could be in the whole middle east where is there would be NO flaring. We have designed flare as well in this project but that would be used only for emergencies. GPF is a stand alone platform with independent utilities and support facilities. The GPF platform is 67.5 meter in length and 43 meters in width. GPF is located at Zakum oilfield, offshore facility about 65 kilometer Northwest of Abu Dhabi. This platform has three main decks, cellar, mezzanine and main. The flare structure consists of a 120 meter long flare bridge with a 80m above sea level angled boom. The distance from the flare tip to the GPF platform is 150 m. There will not be any flaring during normal operation of the GPF, as Zero flaring technology is installed. Hydrocarbon from the GPF platform will be recovered using a Vapour Recovery Unit (VRU) facility. Flaring will only be undertaken during emergency conditions.

Tiziano Gallo Cassarino, Mark Barrett

Research Square · 2021

Abstract With over a third of the United Kingdom's greenhouse gas emissions, decarbonising heat is key to achieving the Government's net-zero target by 2050. Here, we simulate high renewable zero-emission energy system architectures with heat supply based on the major options of district heating, heat pumps, and electrolytic hydrogen boilers. We adopt a novel whole system modelling approach that combines meteorology-driven hourly simulations of demand and supply with storage, flexible technologies, and interconnections on the European scale. Our results show that systems with heat supply based on consumer or district heat pumps require about four times less electricity per unit of heat, with a heat cost about half of that from electrolytic hydrogen boilers. Furthermore, we compare trade-offs between investment in different infrastructure components. For example, we find that, compared to the reference scenario, increasing renewable capacity by 33%, or interconnections by 200%, can lower system storage capacity by up to 50%.

Leah Foecke, Zachary Karson, Thomas Tiberghien

· 2024

As the US public transportation sector accelerates its shift from fossil fuels to zero-emission alternatives, transit agencies and transit bus manufacturers alike face significant uncertainty and instability. This report provides policymakers with updated insights into the US transit bus market, focusing on key industry dynamics, financial challenges with zero-emission bus (ZEB) acquisition, technological obstacles in deployment, and regulatory issues. The research relies on interviews with stakeholders, a detailed review of existing literature, and an analysis of US public transit data. Key findings reveal ongoing challenges related to costs, supply, reliability, and workforce development, all of which hinder the adoption of ZEBs. Specifically, challenges include the reality that purchase prices for zero-emission buses in the United States remain significantly higher than internal combustion engine (ICE) vehicles and have not declined as quickly as previously theorized. Additionally, the full-size ZEB market in the US has become highly consolidated, and most transit agencies lack capacity in terms of technical knowledge, staff, and funding required for a successful transition to ZEBs. Potential options to combat these challenges may include enhanced funding mechanisms, industry partnerships, facilitating access to supporting technologies and best practices, and undertaking initiatives to prepare the ZEB workforce. While more research is needed to support the sector's full transition to ZEBs, this report provides actionable insights policymakers can use in a rapidly evolving market to identify solution areas for further exploration and ease transit into a more sustainable future.

Aiman Rashid, Marco Caredda

Preprints.org · 2023

A layout of urban waste fired zero emission power plant is described in this paper. The principle of layout, which comes from similar coal-fired plants retrieved from the literature, integrates gasification with a power generation section, and implements two parallel conversion processes, one supplied by the heat of the gasifier consisting of a thermoacousticmagnetohydrodynamic (TAMHD) generator, while in the second one the syngas is treated in order to obtain almost pure hydrogen, which is fed to fuel cells. The CO2 deriving from the oxidation of Carbon base is stocked in liquid form. The novelty of the proposed layout lies in the fact that the entire conversion is performed without solid moving parts. The resulting plant avoids any type of emissions in the atmosphere, increases mechanical efficiency as compared to traditional plants, thanks to the absence of moving parts, nonetheless, resolving at its root the ever-increasing waste-related pollution problems.

Gökçe Soydemir, Orestis Panagopoulos

· 2024

This study investigates the degree to which underrepresented construction contractors face challenges in California's zero-emission transportation sector to devise a simpler and more efficient bonding structure. Using a survey dispersed over underrepresented businesses across the state, the study provides several suggestions for a statewide bonding program that caters to the needs of contractors. Both qualitative and quantitative methods are used in the study. The survey data are evaluated using econometric tools to analyze whether there are any statistically significant associations between contractors' characteristics and their industry experiences. Focus groups and focused interviews are conducted to identify those perspectives the survey does not capture, enhancing the quantitative results with firsthand accounts from contractors. This research reveals that many barriers prevent underrepresented businesses from competing effectively and having a more efficient bonding structure. The main obstacles include lack of funds, redundancies in the system such as the retention requirement, insufficient availability of necessary resources, the presence of unconscious bias, problems encountered in guaranteeing faster payments by having a payment clause that works very similarly to the federal system, and relatively high percentages required for bonding and lack of statewide consistency of funding assistance in the bonding process. These businesses exhibit a lack of information and trust regarding the efficacy and accessibility of these programs. The findings indicate the need for legislative changes that prioritize increasing these contractors' access to resources, transparency, prompt automatic payment, and mentee-mentor support. The study also recommends reorganizing the current support systems, such as by implementing an online forum to assist underrepresented contractors, enabling them to compete and cooperate more effectively and contribute to a more equitable and sustainable zero-emission transportation sector in California.

Mafalda S Baptista, Charles K. Lee, Maria R. Monteiro et al.

Environmental Microbiome · 2024

Background Isolating the effects of deterministic variables (e.g., physicochemical conditions) on soil microbial communities from those of neutral processes (e.g., dispersal) remains a major challenge in microbial ecology. In this study, we disturbed soil microbial communities of two McMurdo Dry Valleys of Antarctica exhibiting distinct microbial biogeographic patterns, both devoid of aboveground biota and different in macro- and micro-physicochemical conditions. We modified the availability of water, nitrogen, carbon, copper ions, and sodium chloride salts in a laboratory-based experiment and monitored the microbial communities for up to two months. Our aim was to mimic a likely scenario in the near future, in which similar selective pressures will be applied to both valleys. We hypothesized that, given their unique microbial communities, the two valleys would select for different microbial populations when subjected to the same disturbances. Results The two soil microbial communities, subjected to the same disturbances, did not respond similarly as reflected in both 16S rRNA genes and transcripts. Turnover of the two microbial communities showed a contrasting response to the same environmental disturbances and revealed different potentials for adaptation to change. These results suggest that the heterogeneity between these microbial communities, reflected in their strong biogeographic patterns, was maintained even when subjected to the same selective pressure and that the ‘rare biosphere’, at least in these samples, were deeply divergent and did not act as a reservoir for microbiota that enabled convergent responses to change in environmental conditions. Conclusions Our findings strongly support the occurrence of endemic microbial communities that show a structural resilience to environmental disturbances, spanning a wide range of physicochemical conditions. In the highly arid and nutrient-limited environment of the Dry Valleys, these results provide direct evidence of microbial biogeographic patterns that can shape the communities’ response in the face of future environmental changes. Supplementary Information The online version contains supplementary material available at 10.1186/s40793-024-00587-0.

Guangyue Xu, Ruochen Zhu, Qichan Zhang et al.

Research Square · 2024

Abstract The overuse of fossil energy in industrialization process is a major cause of the frequency of global warming and environmental pollution problems, which seriously threaten the sustainable socio-economic development of Italy and other countries. In response to climate change, Italy has declared a goal of carbon neutrality by 2050. Against this background, this paper selects Italy's carbon emissions from 2011 to 2021 and predicts Italy's future carbon emissions using the GM (1, 1) model. The study results show that Italy's carbon emissions show a decreasing trend, with an average annual rate of change of 1.65% in the process of carbon neutrality. Italy's carbon dioxide emissions will drop to 195.46 million tonnes of carbon dioxide equivalent by 2050, which is about 60.40% lower than the peak in 2005. In addition, according to the capacity of forest carbon sinks, Italy will be able to achieve the carbon neutrality target in 2033. Therefore, this study demonstrates Italy's carbon-neutral promotion strategy and enhances the related carbon-neutral system. It provides some references for other countries, including China, to improve their policy design to promote the green and low-carbon transition of the global economy.

Marilena Maragkaki, Kartikeya Rajput

Eco Cities · 2023

<p>Athens’ extensive urbanisation, lack of green areas and the extreme heat caused by increasingly frequent heat waves indicate the need for actions improving indoor and outdoor comfort, which is closely related to the energy consumption of the buildings. This work’s aim is to create a carbon neutral block in Athens on the 2050 horizon. The optimization of the block’s form based on principles of environmental design and climatic analysis was performed to enhance its environmental benefits. Simulations on the energy performance of the block and calculations on the ability to cover the energy loads by renewables were conducted. Finally, to meet the zero-carbon neutrality, a connection with the neighbouring blocks was established. The results demonstrate the benefits of a bioclimatic, carbon neutral building design in Athens and provide a practical prototype, which can be adapted in other projects, thereby enabling the shift to a more efficient and environmentally friendly built environment.</p>

Ubaida Yousaf, Denise Vonhoegen, Sören Thiele-Bruhn

· 2023

Recent research indicates that soil microbes play a significant role in the formation and turnover of soil organic matter (SOM). Thus, OM is metabolized by microorganisms through intracellular and extracellular enzymatic activity, with one portion of it being converted into biomass and another being respired for energy. This causes an energy and matter flux that is adjusted and slowed down by ongoing recycling of the matter and residual energy. Matter and energy are conserved as much as possible throughout repeating microbial growth cycles, resulting in an "energy use channel," and/or storage as necromass. Soil fertility and several other soil functions depend on the activity of diverse soil microbial populations and, consequently, on continual energy and carbon flows within the soil system. Fluxes and stoichiometry concerns must be considered for the maintenance of microbial diversity and ecosystem activities in soil, including C storage. To comprehend C turnover and sequestration in terrestrial ecosystems, further knowledge of the relationship between element cycling and energy fluxes is required. In this project, we present a conceptual overview of microorganisms as mediators of SOM production, we do that by investigating seven carbon substrates with varying complexity with the same model soil (fertilized Dikopshof) in five different incubation experiments.In the first experiment, we study the effect of substrate size (Glucose — 180 Da, α — 1,4-maltotetraose — 666,6 Da). We hypothesize that exoenzymes would be required to degrade any substrate greater in size than 600 Da, meaning different CUE/EUE due to a change in the process type from growth-oriented processes — high energy flux for glucose degradation to the adaption-oriented processes for the larger substrate, i.e., maltotetraose in this case. The substrates were labelled with 13C to determine various carbon pools in the samples. Destructive sampling was used to obtain subsamples from 6 different time points. Aminosugars and acids were used as markers of microbial biomass/necromass. Chloroform fumigation extraction was performed to determine microbial biomass of carbon and nitrogen. In combination with further data to calculate the microbial quotient (Cmic/OC), the respiratory quotient (qCO2= resp./Cmic), and CUE. Gas flux sampling and isotope selective CO2 analysis to determine the differences in the turnover of the substrates (Energy consumption respiration) The energy accumulation includes the formation of additional biomass, necromass, and metabolites. Analysis of C, H, N, S, O, and P to calculate the stoichiometry of OM.  

Kongzhai Li, Jun Cai, Yuhao Wang et al.

Carbon Neutral Systems · 2025

Abstract Metallurgy represents the primary source of CO 2 emission within China's industrial sector. Blast furnace gas (BFG), rich in CO 2 and CO from ironmaking, serves as the principal contributor to carbon emissions. Transforming these carbon molecules into high-value chemicals or energy products is essential for achieving carbon neutrality in the steel industry. Traditional technologies require extensive separation and purification processes for BFG's CO 2 and CO, resulting in significant energy consumption. Consequently, a major challenge facing the steel industry in advancing flue gas carbon capture lies in developing cost-effective and energy-efficient solutions. This perspective outlines our latest advancements in CO 2 -CO co-hydrogenation for methanol production from BFG. We introduce an innovative approach by integrating blue hydrogen derived from chemical looping, green hydrogen obtained through water electrolysis, and hydrogen sourced from industrial by-products to enhance co-hydrogenation processes. This multifaceted strategy aims to improve carbon sequestration while promoting sustainable hydrogen utilization within chemical production. By developing catalysts for both hydrogen production pathways, we have established high-performance hydrogen reserves. Additionally, we have designed advanced core–shell thermal storage catalysts to optimize methanol synthesis via CO 2 -CO co-hydrogenation. Our research emphasizes the identification of advanced catalytic materials resilient to varying temperatures and pressures—an essential factor for effective hydrogenation. The prepared Cu–ZnO–ZrO 2 catalyst for CO 2 -CO co-hydrogenation achieved a remarkable 52.8% increase in methanol selectivity compared to its commercial counterparts. Additionally, further insights into heat transfer and storage mechanisms will enhance process efficiency, thereby improving energy management and reducing operational costs. This study aims to establish a robust framework addressing carbon emissions while fostering a circular economy through efficient use of resources. The development of a cyclic catalytic system will facilitate industrial-scale CO 2 -CO co-hydrogenation for methanol production, contributing significantly to sustainable development initiatives focused on energy savings and carbon reduction. Graphical abstract

Zhaoyang Luo, Jianning Ren, Simone Fatichi

· 2024

Microbial carbon use efficiency (CUE), describing the partitioning of microbe assimilated carbon into microbial growth and respiration, is commonly used in soil carbon models to link microbial activities with the consumption of soil organic carbon (SOC). However, the role of CUE in regulating SOC storage remains debated. Previous studies have reported that a higher CUE could not only favour SOC formation through microbial necromass accumulation, but also trigger SOC losses because an enhancement in enzyme production facilitates SOC decomposition. The former leads to a positive relationship between CUE and SOC, while the latter leads to a negative one. Temperature dependencies introduce additional uncertainties while exploring the SOC-CUE relationship since temperature affects both SOC decomposition and CUE. Based on the meta-analysis and numerical simulations with a mechanistic model (T&C), we examined the relationship between CUE, SOC storage and temperature. Numerical results recover the expected SOC storage decrease with increasing temperature when temperature effects are isolated; however, an increase of SOC storage with decreasing CUE is found once temperature effects are discounted, indicating that SOC storage increase with increasing CUE is likely a by-product of temperature dependencies. In addition, we show that CUE variability plays a more important role in affecting SOC storage at lower temperature. Our study helps refine the understanding of SOC responses in a warming climate.

M. Spohn

· 2014

Abstract. Soil microbial respiration is a central process in the terrestrial carbon (C) cycle. In this study I tested the effect of the carbon-to-nitrogen (C : N) ratio of soil litter layers on microbial respiration in absolute terms and per unit microbial biomass C. For this purpose, a global dataset on microbial respiration per unit microbial biomass C – termed the metabolic quotient (qCO2) – was compiled form literature data. It was found that the qCO2 in the soil litter layers was positively correlated with the litter C : N ratio and negatively related with the litter nitrogen (N) concentration. The positive relation between qCO2 and litter C : N ratio resulted from an increase in respiration with the C : N ratio in combination with no significant effect of the litter C : N ratio on the soil microbial biomass C concentration. The results suggest that soil microorganisms respire more C both in absolute terms and per unit microbial biomass C when decomposing N-poor substrate. Thus, the findings indicate that atmospheric N deposition, leading to decreased litter C : N ratios, might decrease microbial respiration in soils.

Xianjin He

· 2025

Microbial carbon use efficiency (CUE) affects the fate and storage of carbon in terrestrial ecosystems, but its global importance remains uncertain. Accurately modeling and predicting CUE on a global scale is challenging due to inconsistencies in measurement techniques and the complex interactions of climatic, edaphic, and biological factors across scales. The link between microbial CUE and soil organic carbon relies on the stabilization of microbial necromass within soil aggregates or its association with minerals, necessitating an integration of microbial and stabilization processes in modeling approaches. In this perspective, we propose a comprehensive framework that integrates diverse data sources, ranging from genomic information to traditional soil carbon assessments, to refine carbon cycle models by incorporating variations in CUE, thereby enhancing our understanding of the microbial contribution to carbon cycling.

N Grahamslaw

Historic Ships 2023 · 2023

Brunel’s SS Great Britain, the first iron ship, is conserved and displayed in the historic dry dock where she was built. The most vulnerable parts of the original wrought iron hull are preserved by keeping the surrounding air at 20% relative humidity to prevent corrosion. A glass “sea” at waterline level creates a seal, and bespoke desiccant dehumidifiers desiccate the environment inside and underneath the ship. This conservation method relies on natural gas for drying the air, and electricity for circulating it.

Lisa Göransson

Preprints.org · 2023

This work investigates how to balance the electricity supply and demand in a carbon-neutral northern Europe. Applying a cost-minimizing electricity system model including options to invest in eleven different flexibility measures, cost-efficient combinations of strategies to manage varia-tions are identified. The results of the model are post-processed using a novel method to map the net load before and after flexibility measures are applied to reveal the contribution of each flexi-bility measure. The net load is mapped in the space spanned by the amplitude, duration, and number of occur-rences. The mapping shows that, depending on cost structure, flexibility measures contribute to reduce the net load in three different ways; 1) by reducing variations of long duration but low amplitude, 2) by reducing variations of high amplitude but short duration and low occurrence or 3) by reducing variations of high amplitude, short duration and high occurrence. It is found that cost-efficient variation management is achieved by combining wind and solar power and by combining strategies (1-3) to manage variations. The cost-efficient combination of strategies de-pends on electricity system context where electricity trade, flexible hydrogen and heat production (1) manage the majority of variations in regions with good conditions for wind power while sta-tionary batteries (3) are the main contributors in regions with good conditions for solar power.

Henrik von Storch

· 2020

<p> <em>Deutsche Post DHL Group is the world’s leading logistic company. </em><em>The Group connects people and markets and is an enabler of global trade. It aspires to be the first choice for customers, employees and investors worldwide. To this end, Deutsche Post DHL Group is focusing on growth in its profitable core logistics businesses and accelerating the digital transformation in all business divisions. The Group contributes to the world through sustainable business practices, corporate citizenship and environmental activities. By the year 2050, Deutsche Post DHL Group aims to achieve zero emissions logistics. Deutsche Post DHL Group is home to two strong brands: DHL offers a comprehensive range of parcel and international express service, freight transport, and supply chain management services, as well as e-commerce logistics solutions. Deutsche Post is Europe’s leading postal and parcel service provider. Deutsche Post DHL Group employs approximately 550,000 people in over 220 countries and territories worldwide. The Group generated revenues of more than 63 billion Euros in 2019.</em> <em> </em> <em>Deutsche Post DHL Group’s greenhouse gas footprint was 28.95 million tonnes CO2e in 2019. We acknowledge our responsibility to tackle climate change and have committed to net-zero emissions by 2050 in 2017. We do not only rely on the further development of technologies to reduce our carbon footprint but also on collaboration with our customers and transport partners to achieve the aspired emission reduction. Less knowingly, companies like Deutsche Post DHL group need suitable and reasonable standards for carbon accounting to allocate emissions reduction to the party funding them. Based on the rationale that emissions reduction is not always possible or reasonable where the funds are located but at another location, the concept of carbon offsetting was invented based on the rules set out by the Kyoto Protocol. Carbon offsetting has never been acknowledged in international carbon accounting standards such as the greenhouse gas protocol. The rationale behind this is the target to drive emissions reduction in each and every emitting sector. This is why we call for a new approach to enable faster emissions reduction called insetting. With this approach, emissions reduction become tradable within the sector and independent of local availability of carbon reducing technologies, each and every emitter can contribute to reducing emissions in their sector.</em></p>

Soo Jung Ryu

· 2010

<p>Universities have always had an important leadership role in society in demonstrating the types of changes that need to occur with respect to the prime issues of the time. All around the world, universities are lining up to declare themselves the next carbon neutral school as part of the global trend of becoming "sustainable." But what does it really mean to be carbon neutral? In 2007 Victoria University's School of Architecture and Design (SoAD) declared themselves the first carbon neutral campus in the world through the use of sponsored and purchased carbon credits. However 100% reliance on offset schemes is not the answer as it does not guarantee the capture of carbon forever. Also, the continuing purchase of carbon offsets could be costly and maintaining businessas- usual without any significant changes will result in continuing environmental degradation as a result of the SoAD's unsustainable activities. This research explores various solutions for reducing the three biggest factors that contribute towards the emissions, which are energy, transport and waste. It looks at the difference between behavioural changes (low cost) and technological investment (high cost) in order for SoAD to reduce its carbon footprint to meet three possible reduction targets, established by this research as 25%, 50% and 90%. The findings are that 25% could be saved through simple behavioural changes which cost very little, as they are mainly related to avoiding wastage, 50% could be saved through a combination of low and high cost measures, and 90% comes from considerable investment in new technologies or drastic reduction in use. A further aim of the research is to translate all possible savings into other means, such as knowing how much carbon or land is saved, using a measure such as the ecological footprint, and more importantly what these savings mean to the third world where resources are scarce and expensive. If SoAD's wasteful activities from neglect can be translated into saving people's lives in other nations, it might lead to more responsible energy use. What this research indicates is that for SoAD to be carbon neutral various factors need to be considered and user behaviour is paramount.</p>