Significant Increase In Resistance Research Articles

Experimental Analysis of the Mechanical Behavior of Shear Connectors for Precast Sandwich Wall Panels When Subjected to the Push-Out Tests

Precast concrete sandwich panels consist of two outer layers connected by a central connector and an inner insulating layer that enhances thermal and acoustic performance. A key challenge with these panels is eliminating thermal bridges caused by metallic connectors, which reduce energy efficiency. PERFOFRP connectors, made from perforated glass fiber-reinforced polymer (GFRP) sheets, have been proposed to address this issue. These connectors feature holes that allow concrete to pass through, creating anchoring pins that enhance shear resistance and prevent the separation of the concrete layers. This research aimed to evaluate the effect of the diameter and number of holes on the mechanical strength of PERFOFRP connectors. Three diameters not previously reported in the literature were selected: 12.70 mm, 15.88 mm, and 19.05 mm. A total of 18 specimens, encompassing 6 different configurations with varying numbers of holes, underwent push-out tests. The most significant resistance increase was a 15% gain over non-perforated connectors, observed in the configuration featuring three holes of 19.05 mm. The connections exhibited rigid and nearly linear behavior until failure.

Analysis of the changes of bacterial spectrum and drug resistance in sputum culture of ICU children in a hospital of pediatric in Jiangsu Province from 2017 to 2022

Objective: To investigate the changes of the distribution and drug resistance profile of bacteria from ICU children with lower respiratory tract infection (LRTI) in Suzhou City, Jiangsu Province from 2017 to 2022. Methods: From January 2017 to December 2022, a cross-sectional observational study on the bacterial spectrum analysis among intensive care unit (ICU) children with LRTI was conducted in Children's Hospital of Soochow University. The bacteria was cultivated by culture methods from sputum samples, and identified by MALDI-TOF mass spectrometry. Drug sensitivity tests were performed by the VITEK2 Compact fully automated analysis system and the paper slide method. The χ2 test or Fisher's exact probability was used to analyze the changes of the distribution of sputum culture-positive bacteria and drug resistance in ICU children. Results: The overall detection rate of sputum culture was 42.06% (1 182/2 810). Staphylococcus aureus (25.63%,303/1 182), Acinetobacter baumannii (13.62%,161/1 182) and Haemaphilus influenzae (13.28%,157/1 182) were the top three. Proportions of Acinetobacter baumannii (17.90% vs. 11.02%,χ²=11.17, P=0.001), especially carbapenem-resistant Acinetobacter baumannii (43.70% vs. 23.50%, χ²=15.21, P<0.001) increased significantly from 2020 to 2022. However, the proportions of Haemophilus influenzae (8.50% vs. 16.19%, χ²=14.27, P<0.001), Streptococcus pneumoniae (8.50% vs. 15.92%, χ²=13.42, P<0.001) and extended-spectrum-lactamase producing Escherichia coli (8.89% vs. 18.00%, χ²=5.45, P=0.025) decreased. Drug resistant results showed that Acinetobacter baumannii was obviously more resistant to imipenem (χ²=4.43, P=0.035) and levofloxacin (χ²=12.53, P<0.001), while more sensitive to minocycline (χ²=8.34, P=0.004). Escherichia coli showed a significant increase in resistance to piperacillin tazobactam (χ²=8.29, P=0.008) and cefoperazone sulbactam (χ²=5.07, P=0.024) from 2020 to 2022; Klebsiella pneumoniae consistently maintained a resistance rate of more than 60% to first and second-generation cephalosporins, and remain susceptible to quinolones and carbapenems. Staphylococcus aureus remained highly susceptible to levofloxacin (drug resistance rate: 2.31%,7/303) and sulfamethoxazole/trimethoprim (drug resistance rate: 4.95%,15/303) from 2020 to 2022. Conclusion: Higher detection and resistance rates of Acinetobacter baumannii from sputum culture in ICU children from 2020 to 2022 were explored. Resistance of Escherichia coli to β-lactamase inhibitor combinations was more serious. Regular monitoring the changes of the etiology of respiratory tract infections in ICU Children is particularly important for the prevention and treatment of multidrug-resistant bacterial infections.

Cross-resistance patterns in field strains of the sheep blowfly following laboratory-based selection pressure with dicyclanil or imidacloprid

Control of the sheep blowfly relies largely on the use of insecticides applied prophylactically in advance of expected fly activity. However, the blowfly has shown an ability to develop resistance to some of these insecticides. Recent reports of the co-occurrence of resistance to both dicyclanil and imidacloprid in in vitro bioassays with field-collected fly strains has raised the possibility that the two resistances may represent cross-resistance linked by a common mechanism. We investigated this by imposing insecticide selection pressure on larvae of two insecticide-resistant field strains over a number of generations using either dicyclanil or imidacloprid and then measuring changes in sensitivity to both the selecting chemical and the alternate chemical. Larvae selected over six generations with each chemical showed significant increases in resistance to the selecting chemical: resistance ratios at the IC50 5.5 - 8.1-fold higher for dicyclanil, and 3.1 - 3.8-fold for imidacloprid. The larvae also showed significant increases in levels of resistance towards the alternate chemical: resistance ratios 2.6 - 3.1-fold higher towards dicyclanil following selection with imidacloprid, and 2.2 - 3.2-fold higher towards imidacloprid following selection with dicyclanil. The increases in resistance to both chemicals after exposure to either suggests a common mechanism of resistance, at least in our laboratory-selected populations. Assays with the cytochrome P450 inhibitor aminobenzotriazole showed that this synergist was able to remove the increased resistance to both compounds in strains selected with either compound, suggesting that cytochrome P450 is responsible for the resistance observed to both chemicals. Our results confirm that cross-resistance exists between dicyclanil and imidacloprid in the sheep blowfly, and hence the two compounds should be considered as related entities in insecticide rotation strategies for flystrike control.

500 μm heavy micro-alloyed Cu wire for IGBT application: The study on microstructure characteristics, electrical fatigue fracture mechanism and bonding reliability

In this study, we introduced trace amounts of silver and nickel into 500 μm diameter copper wires to form micro-alloyed copper wires used in insulated gate bipolar transistors (IGBT). The addition of silver and nickel enhanced the mechanical properties of the conductors and suppressed the work hardening effect, significantly improving the power cyclic lifetime. Additionally, this study conducted chlorination and high-temperature oxidation test to compare the application characteristics of the heavy micro-alloyed copper wires with pure copper wires, through tensile and bending test, as well as electrical property comparisons. Finally, Cu50Ni (50 ppm Ni) wires were selected and nickel ceramic substrates for wire bonding to evaluate module electrical properties and bonding reliability.In the chloride test, there was no significant pitting corrosion observed in copper wire, and the micro-alloyed copper wire outperformed the pure copper wires in terms of bending lifetime and power cycling performance. In the high-temperature oxidation test, an oxide layer of cuprous oxide formed on the surface of all wires. The pure copper wire exhibited a significant increase in resistance. Notably, the micro-alloyed copper wires had better resistance to oxidation. Regarding wire bonding, the use of Cu50Ni wires and nickel ceramic substrates reduced the diffusion rate of nickel atoms from the substrate to the copper wire, forming a thinner alloy diffusion layer. This prevented electrical degradation and achieved high bonding reliability, especially under higher bonding forces. These findings confirm that micro-alloyed copper wires are suitable for high-power applications.

Experimental response of thin RC walls seismically strengthened with steel plates

In some Latin American countries, and especially in Colombia, the industrialized system of thin and slender walls has been chosen for the construction of residential buildings, thus reducing costs and increasing efficiency of construction processes. However, these walls differ considerably from traditional concrete wall system due to their reduced thickness, reinforcement detailing, and use of nonductile electro-welded reinforcement, which increases their seismic vulnerability, especially in tall buildings and in high seismic hazard zones. Strengthening proposals for walls with these specific characteristics of the industrialized system are scarce; therefore, it is necessary to evaluate alternatives that allow for improving their seismic performance. This article presents the experimental response of a thin wall that was brought to failure and subsequently repaired and strengthened with externally bonded steel plates to evaluate the effectiveness of the repair process and the strengthening. Additionally, the results of two thin walls externally strengthened with steel plates and bolts are presented, and their response is compared with that of the original walls. All the specimens were subjected to the same type of test under cyclical lateral load and constant axial load until failure. The behavior observed in the rehabilitated wall showed that it is possible to restore the stiffness of a wall that has previously been brought to a severe level of damage and increase its displacement capacity with the strengthening. In strengthened walls without previous damage, the displacement capacity was increased between 25 % and 43 %, reaching a roof drift of up to 2.0 % without a significant increase in resistance. A noticeable increase was obtained in the amount of dissipated energy (greater than 80 %), and the rupture of web reinforcement and buckling of longitudinal reinforcement of the boundaries were delayed for average drifts of 43 % and 32 % higher than in the original walls, respectively.

Increasing trends of antibiotic resistance in Uganda: analysis of the national antimicrobial resistance surveillance data, 2018–2021

BackgroundContinuous monitoring of antimicrobial resistance (AMR) in Uganda involves testing bacterial isolates from clinical samples at national and regional hospitals. Although the National Microbiology Reference Laboratory (NMRL) analyzes these isolates for official AMR surveillance data, there's limited integration into public health planning. To enhance the utilization of NMRL data to better inform drug selection and public health strategies in combating antibiotic resistance, we evaluated the trends and spatial distribution of AMR to common antibiotics used in Uganda.MethodsWe analyzed data from pathogenic bacterial isolates from blood, cerebrospinal, peritoneal, and pleural fluid from AMR surveillance data for 2018–2021. We calculated the proportions of isolates that were resistant to common antimicrobial classes. We used the chi-square test for trends to evaluate changes in AMR resistance over the study period.ResultsOut of 537 isolates with 15 pathogenic bacteria, 478 (89%) were from blood, 34 (6.3%) were from pleural fluid, 21 (4%) were from cerebrospinal fluid, and 4 (0.7%) were from peritoneal fluid. The most common pathogen was Staphylococcus aureus (20.1%), followed by Salmonella species (18.8%). The overall change in resistance over the four years was 63–84% for sulfonamides, fluoroquinolones macrolides (46–76%), phenicols (48–71%), penicillins (42–97%), β-lactamase inhibitors (20–92%), aminoglycosides (17–53%), cephalosporins (8.3–90%), carbapenems (5.3–26%), and glycopeptides (0–20%). There was a fluctuation in resistance of Staphylococcus aureus to methicillin (60%-45%) (using cefoxitin resistance as a surrogate for oxacillin resistance) Among gram-negative organisms, there were increases in resistance to tetracycline (29–78% p < 0.001), ciprofloxacin (17–43%, p = 0.004), ceftriaxone (8–72%, p = 0.003), imipenem (6–26%, p = 0.004), and meropenem (7–18%, p = 0.03).ConclusionThe study highlights a concerning increase in antibiotic resistance rates over four years, with significant increase in resistance observed across different classes of antibiotics for both gram-positive and gram-negative organisms. This increased antibiotic resistance, particularly to commonly used antibiotics like ceftriaxone and ciprofloxacin, makes adhering to the WHO's Access, Watch, and Reserve (AWaRe) category even more critical. It also emphasizes how important it is to guard against the growing threat of antibiotic resistance by appropriately using medicines, especially those that are marked for "Watch" or "Reserve."

Epidemiology and antimicrobial resistance trends of pathogens causing urinary tract infections in Mwanza, Tanzania: A comparative study during and after the implementation of the National Action Plan on Antimicrobial Resistance (2017-2022)

ObjectivesTo delineate the epidemiology and antimicrobial resistance (AMR) trends of pathogens causing urinary tract infections (UTIs) during (June 2019-June 2020) and after (March-July 2023) the implementation of the National Action Plan on AMR 2017-2022 in Mwanza, Tanzania. MethodsThis cross-sectional study was conducted among 2097 patients with clinical symptoms of UTIs during (n = 1144) and after (n = 953) the National Action Plan on AMR 2017-2022. Quantitative urine culture was done to isolate significant bacteria causing UTI, which were then identified to the species level and tested for antimicrobial susceptibility. Tabulations, descriptive, and logistic regression analyses were used to analyze categorical and continuous variables, as well as the association between outcome and independent variables. Statistical significance was defined as P ≤0.05 at a 95% confidence interval (CI). ResultsThe overall prevalence of culture-positive UTIs was 22.8% (479 of 2097; 95% CI: 21.1-24.7%), with no significant difference between the study periods (21.8% [249 of 1144; 95% CI: 19.5-24.3%]) vs 24.1% (230 of 953; 95% CI: 21.5-26.9%), P = 0.274). We observed a significant increase in resistance to ciprofloxacin (32.0% vs 45.8%, P = 0.0481) and third-generation cephalosporins (marked by extended-spectrum β-lactamase–producing Enterobacterales [ESBL-PE], 38.7% vs 56.9%, P = 0.0307). Additionally, UTIs caused by ESBL-PE is significantly common among patients in higher-tier hospitals (58.4% vs 34.0%; OR [95% CI]: 2.51 [1.41-4.48], P = 0.002). ConclusionsThere was a significant increase in bacterial resistance to ciprofloxacin and third-generation cephalosporins, as well as ESBL-PE. These results emphasize the critical need to enhance AMR surveillance, improve infection prevention and control measures, and strengthen antimicrobial stewardship programs.

The Effect of Antibiotics on the Eradication of Multidrug-Resistant Organisms in Intestinal Carriers-A Systematic Review with Meta-Analysis.

The aim of this systematic review was to investigate the effect of antibiotics on the eradication of multidrug-resistant organisms (MRO) in intestinal carriers. We defined multidrug-resistant organisms as vancomycin-resistant Enterococcus faecium (VREfm), and multidrug-resistant Gram-negative Enterobacterales. Methods: We searched the EMBASE, Cochrane Central, and PubMed databases from inception to medio November 2023. We included randomised and controlled clinical trials (RCTs), that investigated the effect of antibiotics on the eradication of multidrug-resistant organisms in intestinal carriers. Finally, we performed a meta-analysis. We included five RTCs in the systematic review. In four studies an effect of antibiotics on the eradication of MRO was shown at the end of intervention, but it was not sustained at follow-up. In the fifth study, the effect at the end of intervention was not reported, and there was no observed effect of the intervention at follow-up. We included four studies in the meta-analysis, and it suggests an effect of antibiotics on the eradication of MRO in intestinal carriers at the end of follow-up with a p-value of 0.04 (95% confidence interval 1.02-1.95). None of the studies reported a significant increase in resistance to the study drug. Gastrointestinal disorders were the most frequent non-severe adverse event. The effect of antibiotics on the eradication of multidrug-resistant organisms in intestinal carriers was not statistically significant in any of the five included studies; however, we found a significant effect in the pooled meta-analysis. As the confidence interval is large, we cannot determine the clinical importance of this finding, and it should be further investigated.

Microbiological profile of patients with orthopedic implant-associated infection in the post-COVID period

Background. The etiological structure of implant-associated infection and antibiotic resistance of pathogens are important when choosing empirical antibiotic therapy. COVID-19 pandemic and increased consumption of antibiotics by the population could provoke an increase in antibiotic resistance.The aim of the work. To compare the spectrum of leading pathogens of implantassociated infection in the pre- and post-Covid period and to assess antibiotic resistance.Materials and methods. A continuous retrospective study of biomaterial samples from traumatology and orthopedic patients with implant-associated infection was carried out for 2018–2019 and 2021–2022. The sample consisted of 548 microorganism strains (n = 237 and n = 317, respectively) in 442 cases of infectious complications. The antibiotic resistance of all isolated microorganisms, including those from microbial associations, was assessed.Results. The leading pathogen of monomicrobial implant-associated infection in both study periods was Staphylococcus epidermidis (33–37 %). In 2021–2022, the proportion of microbial associations increased (from 12.5 to 17.5 %; p = 0.147) with the appearance of fungi in the microbial landscape. In the post-Covid period, the increase in Staphylococcus aureus resistance to tetracycline and doxycycline was revealed; the isolation of methicillin-resistant strains among Staphylococcus aureus decreased from 4 cases (out of 187) to 3 (out of 232); 100 % sensitivity to rifampicin and co-trimoxazole was maintained. An increase in Staphylococcus epidermidis resistance to all tested antibiotics was detected (statistically significant increase in resistance to fluoroquinolones; p = 0.002–0.003) with the isolation of methicillin-resistant strains in 80.5% and 80.9% of cases, respectively. All staphylococcal isolates were susceptible to vancomycin and linezolid. Enterobacteriaceae representatives showed a decrease in resistance to carbapenems and an increase in resistance to co-trimoxazole; in Pseudomonas aeruginosa and Acinetobacter baumannii, there is an increase in resistance to carbapenems and fluoroquinolones. All gram-negative microorganisms were sensitive to colistin.Conclusion. The high frequency of isolation of methicillin-resistant staphylococci determines the choice of vancomycin for empirical therapy. Increasing resistance of staphylococci to fluoroquinolones may limit their use. Increasing resistance of gram-negative bacteria and a narrow spectrum of antibiotics acting on carbapenemase producers may reduce the effectiveness of therapy.

Electrochemical and Fluorescence MnO2-Polymer Dot Electrode Sensor for Osteoarthritis-Based Peroxisomal β-Oxidation Knockout Model.

A coenzyme A (CoA-SH)-responsive dual electrochemical and fluorescence-based sensor was designed utilizing an MnO2-immobilized-polymer-dot (MnO2@D-PD)-coated electrode for the sensitive detection of osteoarthritis (OA) in a peroxisomal β-oxidation knockout model. The CoA-SH-responsive MnO2@D-PD-coated electrode interacted sensitively with CoA-SH in OA chondrocytes, triggering electroconductivity and fluorescence changes due to cleavage of the MnO2 nanosheet on the electrode. The MnO2@D-PD-coated electrode can detect CoA-SH in immature articular chondrocyte primary cells, as indicated by the significant increase in resistance in the control medium (R24h = 2.17 MΩ). This sensor also sensitively monitored the increase in resistance in chondrocyte cells in the presence of acetyl-CoA inducers, such as phytol (Phy) and sodium acetate (SA), in the medium (R24h = 2.67, 3.08 MΩ, respectively), compared to that in the control medium, demonstrating the detection efficiency of the sensor towards the increase in the CoA-SH concentration. Furthermore, fluorescence recovery was observed owing to MnO2 cleavage, particularly in the Phy- and SA-supplemented media. The transcription levels of OA-related anabolic (Acan) and catabolic factors (Adamts5) in chondrocytes also confirmed the interaction between CoA-SH and the MnO2@D-PD-coated electrode. Additionally, electrode integration with a wireless sensing system provides inline monitoring via a smartphone, which can potentially be used for rapid and sensitive OA diagnosis.

Role of endogenous soil microorganisms in controlling antimicrobial resistance after the exposure to treated wastewater

The reuse of treated wastewater (TWW) for irrigation appears to be a relevant solution to the challenges of growing water demand and scarcity. However, TWW contains not only micro-pollutants including pharmaceutical residues but also antibiotic resistant bacteria. The reuse of TWW could contribute to the dissemination of antimicrobial resistance in the environment. The purpose of this study was to assess if exogenous bacteria from irrigation waters (TWW or tap water-TP) affect endogenous soil microbial communities (from 2 soils with distinct irrigation history) and key antibiotic resistance gene sul1 and mobile genetic elements intl1 and IS613. Experiments were conducted in microcosms, irrigated in one-shot, and monitored for three months. Results showed that TP or TWW exposure induced a dynamic response of soil microbial communities but with no significant increase of resistance and mobile gene abundances. However, no significant differences were observed between the two water types in the current experimental design. Despite this, the 16S rDNA analysis of the two soils irrigated for two years either with tap water or TWW resulted in soil microbial community differentiation and the identification of biomarkers from Xanthomonadaceae and Planctomycetes families for soils irrigated with TWW. Low-diversity soils were more sensitive to the addition of TWW. Indeed, TWW exposure stimulated the growth of bacterial genera known to be pathogenic, correlating with a sharp increase in the copy number of selected resistance genes (up to 3 logs). These low-diversity soils could thus enable the establishment of exogenous bacteria from TWW which was not observed with native soils. In particular, the emergence of Planctomyces, previously suggested as a biomarker of soil irrigated by TWW, was here demonstrated. Finally, this study showed that water input frequency, initial soil microbial diversity and soil history drive changes within soil endogenous communities and the antibiotic resistance gene pool.

Does selective digestive decontamination (SDD) increase antibiotic resistance? Long-term comparison of two intensive care units (with and without SDD) of the same tertiary hospital

PurposeThe aim of this study was to to compare the antimicrobial resistance rate and its relationship with the antibiotic consumption in two separate Intensive Care Units (ICUs) of the same hospital, one with and other without selective decontamination of the digestive tract (SDD).MethodsWe performed a retrospective study in the two ICUs of the Araba University Hospital. Trauma and neurosurgical patients are admitted to the SDD-ICU, and general digestive surgery patients go to the no SDD-ICU. From 2014 to 2018 we analyzed the number of isolates, and the bacterial resistance trends of 47 antimicrobial-microorganism combinations. Additionally, antimicrobial consumption was estimated in both ICUs. Resistance rates were also compared with those reported in ENVIN-HELICS Spanish national registry.ResultsIn the ICU with SDD protocol, there was a significant decrease in the resistance of E. coli to amoxicillin/clavulanic acid and in the resistance of E. faecalis to high concentration of gentamycin and high concentration of streptomycin. A significant increase of resistance of Staphylococcus coagulasa negative (CoNS) to linezolid in the no SDD-ICU was also detected. Overall, the level of resistance in the SDD-ICU was lower or of the same order than in the ICU without SDD and that reported in the Spanish national registry.ConclusionsSDD had neither a clinically relevant impact on emergence and spread of resistance, nor in the overall systemic antimicrobial use. The patient type rather than the SDD protocol showed to condition the ecology and therefore, the resistance rate in the ICUs.

Abstract A026: EGF/EGFR signaling in priming for resistance to BRAF/MEK inhibitors in melanoma

Abstract Targeted therapies kill cancer cells very efficiently. However, the effectiveness of targeted therapies is limited by the eventual emergence of resistance, arising from a small subset of cells capable of surviving therapy. Our work has shown genetically homogeneous cells, in distinct transcriptomic states, are capable of surviving combination BRAF and MEK inhibition. In the presence of targeted therapies these rare cells transform into resistant cells, we therefore call these cells ‘primed’ for resistance. Our research has focused on characterizing these primed cells, however, the mechanisms of survival remain unknown. Since primed cells overexpress receptor tyrosine kinases (RTKs), which are associated with growth and survival, we tested if overexpression of the RTK EGFR could explain priming and subsequent resistance. While melanoma cells in which we artificially overexpressed EGFR had no significant increase in resistance, EGFR overexpressing cells in the presence of exogenous EGF are highly resistant to combination BRAF/MEK inhibition. While EGF is not overexpressed in primed cells, preliminary data suggests that while most cells reduce EGF expression in the presence of BRAF/MEK inhibition, primed cells maintain their baseline expression, potentially maintaining EGF/EGFR signaling in these colonies. We are therefore testing if EGF/EGFR signaling is necessary in vitro by knocking out EGF or EGFR. Furthermore, to test if EGF/EGFR signaling can create a primed state, we used flow cytometry to determine expression of the prime cell marker NT5E. In cells with confirmed EGFR overexpression we observed an increased fraction of NT5E overexpressing cells, suggesting that EGF/EGFR signaling could initiate aspects of primeness beyond simple survival. Further research will determine if EGF/EGFR signaling can initiate an overall primed transcriptional state. The heritability of any primeness as a consequence of EGF/EGFR signaling will inform us if this signaling is a potential cause of priming or a mechanism by which paracrine signaling and/or stromal protection can eventually result in independent resistance. Citation Format: Robert J. Vander Velde, Sydney M. Shaffer. EGF/EGFR signaling in priming for resistance to BRAF/MEK inhibitors in melanoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr A026.

Deaeration of incubation buffer to minimize electrochemical impedance spectroscopy signal drift on screen-printed gold electrodes and its use for label-free detection of vancomycin

Disposable screen-printed gold electrodes (SPAuEs) are used for the development of numerous immunosensors owing to their ease of modification with biorecognition molecules. A major limitation in the development of SPAuEs based biosensors is the single-use of the electrodes leading to higher costs for sensor development, whereas multiple measurements can affect the sensor stability and reproducibility. Especially, label-free electrochemical impedance spectroscopy (EIS) based SPAuEs sensors are prone to signal drift resulting in false-positive or false-negative data questioning the reliability of the assay. We found that repeated EIS measurements on SPAuEs in ferri- and ferrocyanide solution yielded a significant increase in resistance to charge transfer (Rct) value (positive signal drift) even in a control solution (without the target analyte). The positive signal drift follows the typical pattern of a concentration-dependent calibration curve, rendering repeated measurement error-prone for sensing purposes. In this study, it is shown that the incubation of the SPAuEs in nitrogen purged deaerated phosphate buffered saline (N-PBS) minimized this signal drift in repeated/multiple EIS measurements. This method was then used to develop a peptide-based EIS biosensor for the detection of Vancomycin, a last-line antibiotic used for the treatment of severe multidrug-resistant bacterial infection. This protocol can be followed for the biosensing of other clinically important biomarkers.

Stability of Silver-Nanowire-Based Flexible Transparent Electrodes under Mechanical Stress

Flexible transparent electrodes are integral to the advancement of flexible optoelectronic devices such as flexible displays and solar cells. However, indium tin oxide (ITO), a traditional material used in transparent electrodes, exhibits a significant increase in resistance under mechanical stress, which limits the long-term stability of flexible devices. Here, we prepare various types of silver nanowire (AgNW)-based transparent electrodes and investigate their stability in terms of electrical resistance and optical transmittance under compressive and tensile stresses. Under compressive stress, ITO on a polyethylene terephthalate (PET) substrate exhibits a significantly high electrical resistance of &gt;3000 Ω after 1000 stress cycles, while the AgNW-coated electrode on a PET film exhibits a relatively smaller resistance of &lt;1200 Ω. The AgNW-embedded electrode in a UV-curable polymer matrix (NOA63 or NOA71) exhibits an even lower electrical resistance of &lt;450 Ω because AgNWs can easily maintain their network. A similar trend is observed under tensile stress. The AgNW-embedded electrode shows the highest resistance stability, whereas the ITO on the PET substrate shows the poorest stability. The optical transmittance is comparable regardless of the type of stress or electrode used. This superior stability of the AgNW-based electrodes, realized by integrating it with a polymer matrix, is promising for the development of durable and high-performance flexible optoelectronic devices.

Antimicrobial resistance and genomic investigation of Salmonella isolated from retail foods in Guizhou, China.

Salmonella is a major foodborne pathogen worldwide that causes severe morbidity and mortality. It is mainly caused by consuming contaminated food, with retail food considered the primary source. In Guizhou, China, 102 Salmonella strains isolated from 2016 to 2021 underwent phenotypic antimicrobial resistance testing and whole-genome sequencing (WGS) to understand Salmonella diversity, including serotypes, sequencing types (STs), antimicrobial genes, virulence genes, plasmid types, multi-locus sequence types (MLST), and core genome MLST (cgMLST). S.Typhimurium was the dominant serotype, and O:4(B) was the leading serogroup. The most prevalent genotype was ST40. Phenotypic antimicrobial resistance identified 66.7% of the sampled isolates as multi-drug resistant (MDR). S.Enteritidis (n = 7), S.Typhimurium (n = 1), S.Indiana (n = 1), S.Kentucky (n = 1), S.Uganda (n = 1), all of which were MDR, were resistant to Colistin. Resistance rates varied significantly across different strains and food types, particularly meat products exhibiting higher resistance. Notably, significant increases in resistance were observed from 2016 to 2021 for the following: ≥ 1 resistant (P = 0.001), MDR (P = 0.001), ampicillin (P = 0.001), tetracycline (P < 0.001), chloramphenicol (P = 0.030), and trimethoprim/sulfamethoxazole (P = 0.003). The marked escalation in drug resistance over the recent years, coupled with the varying resistance rates among food sources, underscores the growing public health concern. Our findings highlight the need for a coordinated approach to effectively monitor and respond to Salmonella infections in Guizhou, China.

Water Dissociation Interfaces in Bipolar Membranes for H2 Electrolysers

In order to meet large scale energy demands in a more sustainable way, water electrolysers could be coupled with the well-developed photovoltaic solar cell technology to provide the energy input for green H2 production. Commercial PEM (proton exchange membranes) electrolysers operate in acidic pH which favours H2 production at the cost of using IrO2 as catalyst for oxygen production at the anode representing a significant drawback for this technology. Contrary, an AEM (anionic exchange membranes) operates in alkaline electrolytes which enables the use of low cost and highly active OER catalyst such as NiCoFeOx,1 however at the expense of including an extra overpotential to drive the H2 production in the electrolyser.2 Using bipolar membranes (BPM), where a cationic exchange membrane CEM is used alongside an anionic exchange membrane, allows the electrolyser to operate at different pHs: at the cathode in an acidic environment to favour H2 production, and alkaline for O2 production at the anode. However, a BPM induces a significant increase in resistance across the electrolyser.2 Recently, it has been demonstrated that by adding metal oxides as water dissociation catalysts, the electrolyser overpotential significantly decreased passing from 8 V to 2.2 V at 500 mA cm-2.3 This milestone in the field was accomplished by using two metal oxides with different point of zero charge (PZC) 3 and 11 for IrO2 and NiO respectively. Interestingly, a similar performance was observed when only TiO2 was used as water dissociation catalyst which PZC sits between IrO2 and NiO.4 Indeed demonstrating the necessity of better understanding of the physicochemical phenomena that governs water dissociation interfaces.Using TiO2 as water dissociation catalyst provides a suitable platform to understand how properties such as conductivity or different doping content affect water dissociation during H2 production in the electrolyser. Therefore, in this work modifications of TiO2 were investigated and its impact on the cell voltage when used between Nafion 212 and Sustainion membranes as CEM and AEM respectively, in a commercial 5 cm2 electrolyser at 60 ⁰C that operates only with DI water. To only benchmark the performance of the BPM, Pt and IrO2 were chosen as H2 and O2 catalysts respectively.

Resistive Switching in Bigraphene/Diamane Nanostructures Formed on a La3Ga5SiO14 Substrate Using Electron Beam Irradiation.

Memristors, resistive switching memory devices, play a crucial role in the energy-efficient implementation of artificial intelligence. This study investigates resistive switching behavior in a lateral 2D composite structure composed of bilayer graphene and 2D diamond (diamane) nanostructures formed using electron beam irradiation. The resulting bigraphene/diamane structure exhibits nonlinear charge carrier transport behavior and a significant increase in resistance. It is shown that the resistive switching of the nanostructure is well controlled using bias voltage. The impact of an electrical field on the bonding of diamane-stabilizing functional groups is investigated. By subjecting the lateral bigraphene/diamane/bigraphene nanostructure to a sufficiently strong electric field, the migration of hydrogen ions and/or oxygen-related groups located on one or both sides of the nanostructure can occur. This process leads to the disruption of sp3 carbon bonds, restoring the high conductivity of bigraphene.

Microfluidic Assessment of T Cell Deformability and Capillary Network Occlusion

Introduction: Adoptive T cell therapies offer a new frontier of cancer treatment that disrupts the conventional chemotherapy paradigm. Naïve T cells can be genetically modified to directly target cancerous cells and have proven to be aggressively effective in fighting cancers resistant to chemotherapies. A major challenge that adoptive T cell therapies face is successfully delivering the cell products to the location of the target cells, which is particularly challenging in the case of solid tumors. A complete characterization of the biomechanical properties of T cell products would help researchers gain insight into the capacity of these engineered cells to navigate and extravasate through vasculature and tumor microenvironments. Previous studies have found that T cell volume, cortical tension, and dynamic resistance increase with activation (Waugh et al. Front Bioeng Biotechnol. 2023). A simple and reproducible method to easily quantify and assess such cellular properties has yet to be established. Presently, we describe a microfluidic assay for the rapid and robust characterization of the mechanical changes of T cells upon activation. Our assay models the microcapillaries through a gradient of micropillar arrays, which allows for the evaluation of T cells perfused through the network. The spacing between pillars is 12 µm at the first array, similar to small arterioles, and incrementally decreases to 3 µm spacing in the last array, mimicking small capillaries ( Figure 1A). Trafficking of adoptive T cell therapies through the microvasculature networks of this scale into their target tissues represents a persistent and major challenge facing these therapies (Marofi et al. Stem Cell Res. Ther. 2021). Methods: The microfluidic devices were fabricated by casting polydimethylsiloxane (PDMS) on a silicone wafer fabricated through photolithographic protocols. Devices contain arrays of pillars measuring 20 µm x 10 µm x 12 µm with gradient spacing beginning at 12 µm at the inlet and 3 µm at the outlet. Jurkat T cells were cultured in RPMI 1640 medium with 10% fetal bovine serum and used in a naïve state or activated via antibody stimulation of CD3 and CD28. T cells were then suspended in growth media at 1x10 6 cells/mL. Microchannels were wetted and cleaned with 100% ethanol perfused at 10 µL/min for 15 minutes followed by cell culture media at 10 µL/min for 15 minutes to block the non-specific binding sites on the PDMS and to create a biocompatible environment for the cell sample. The devices were connected to a digital pneumatic pressure-based flow pump system. The cell sample was perfused at 100 mBar for 7 minutes and a subsequent wash process with growth media at 100 mBar for 7 minutes was performed to flush non-occluded cells. Upon completion of the experiment, the channel was scanned using Phase and DAPI filters with an Olympus IX83 inverted motorized microscope, and occluded T cells were quantified using ImageJ. Results: Our assay showed distinct levels of T cell occlusion upon activation through CD3 and CD28 stimulation. Naïve T cells showed lower levels of occlusion in each of the first five arrays compared to activated T cells, while both groups showed high levels of occlusion in the final 3 µm array. Activated T cells showed approximately three times the amount of occlusion in the second through fifth arrays. To assess overall occlusion, we use the Occlusion Index (OI), which considers the density of pillars and the number of cells caught in each array. We found that activated T cells had a significantly higher OI when compared to non-activated T cell samples (p &amp;lt; 0.05, unpaired t-test). Naïve T cells had an OI mean of 24.4 ± 5.0 while activated T cells had a mean of 42.5 ± 5.6 ( Figure 1B). Conclusions: Our results show that there is a significant increase in resistance of activated T cells through a microvasculature-modeled environment compared to their naïve counterparts. As adoptive T cell therapies increase in popularity, a complete understanding of the biomechanical properties of these cell products will be necessary for effective design. Our microfluidic assay mimics the narrowing channels of the microvasculature and permits the study of how naïve and engineered T cells travel through these mechanically challenging spaces.

Effectiveness of composite jacket strengthening of reinforced concrete columns under eccentric load after fire exposure

This research presents a numerical study of the behavior of reinforced columns with a square cross section subjected to eccentric stress under the influence of fire. As a first step, the study examined the effects of exposing columns to fire with an increasing temperature up to 600°C for 60 minutes under eccentric loading conditions (e/b = 0, 0.1, 0.15, 0.20). As a second step, the columns were strengthened with a 100-mm concrete jacket and shirts supported by a steel structure consisting of vertical angles and horizontal spreaders to determine the effectiveness of the strengthening in increasing the resistance of these damaged columns. After the fire, this type of reinforcement is considered better than reinforcement with concrete shirts, reinforcement with carbon fiber-reinforced polymers, and others because of its advantages. There are many advantages to the ease and speed of implementation. The results showed that the columns that were repaired and strengthened after the fire with the steel structure casing led to a significant increase in resistance. It was found that the greater the thickness of the steel structure, the greater the resistance, and that the greater the eccentricity ratio, the lower the resistance as well as the collapse load.