Increase In Resistance Research Articles

12328 Multimodal Imaging Reveals Changes In Beta Cell Metabolism And Heterogeneity Throughout Pregnancy

Abstract Disclosure: J.M. Cuala: None. T. Singh: None. C. Deng: None. K. Jayapalan: None. S. Dhawan: None. K. White: None. S. Georgia: None. During pregnancy, a unique, transient metabolic stressor, pancreatic islets adapt by balancing hormone production to maintain tight glucose homeostasis. Maternal insulin demand increases as systemic insulin resistance increases. To keep up with the increase in demand, beta cell functional dynamics change throughout pregnancy, including increasing insulin synthesis and lowering the threshold for glucose-stimulated insulin secretion (GSIS). Failure to adapt can lead to gestational diabetes (GD), a complication in 14% of pregnancies worldwide, feeding into a vicious cycle of impaired function and, eventually, hyperglycemia. Fundamentally, beta cell function is dictated by its metabolism, calcium signaling, and insulin content upon glucose stimulation. To better understand how beta cell maladaptation during pregnancy leads to gestational diabetes, we propose to apply a multidisciplinary approach to integrate novel tools to assess function and metabolism fluctuations throughout normal pregnancy. Using live isolated islets from wild-type C57BL/6 (BL6) and InsCre-gCAMP6f fl/fl (INS-gCAMP) mice, we will measure GSIS and take 4D images using metabolic fluorescence lifetime imaging (FLIM) and confocal microscopy to visualize and quantify metabolic and functional changes at different time points at cellular resolution. We expect functional and metabolic capacity levels to increase during the onset of beta cell remodeling (∼Day 8) and continue to peak throughout pregnancy. In contrast, changes in beta cell heterogeneity become more evident at the peaks of beta cell proliferation and expansion (∼Day 11-14). The proposed study will implement novel techniques to establish beta cell functional and metabolic information within a 3D pancreatic islet context throughout different time points of pregnancy. With this, we will provide greater insight into beta cell biology and its adaptation to metabolic stress to better understand the progression of gestational diabetes, which can then be applied to investigate other cellular adaptive dynamics that affect health and disease. Presentation: 6/2/2024

Non-smooth discrete element method analysis of channel width's effect on ice resistance in broken ice field

A numerical model based on NDEM is used to investigate the effect of channel width on broken-ice resistance in the channel. The model incorporates a limited impulse method to simulate the ice crushing failure. The accuracy of the numerical model is benchmarked against experimental data from model tests conducted on the Araon icebreaker at KRISO. The simulations successfully capture the characteristic effects of channel width on broken-ice resistance observed in the experiment. Beyond benchmarking of the numerical model, this study analyses the force chain characteristics in the broken ice field, revealing the crucial role of force chains in the resistance increase caused by channel width constraints. Building upon the established numerical model, further sensitivity analyses are conducted to investigate the correlation between channel width effect and other relevant factors such as ice concentration, ship velocity and ice thickness. Among these factors, it is found that ice concentration emerges as the predominant determinant of the critical channel width. The increase in ice resistance attributable to the channel width is exacerbated under the condition of thicker ice floes and lower ship velocity, where the occurrence of ice floe rotation is less frequent and the corresponding force chains are stronger and more stable.

High sound pressure level sound absorption in acoustic resonant metamaterials: adapting a mass-spring model for nonlinear effects

In aerospace, conventional materials as micro-perforated panels backed by cavities are used to absorb sound at high sound pressure levels. These solutions are not optimal at low frequencies compared to resonant acoustic metamaterials, which present an acoustic absorption peak with a wavelength-to-thickness ratio greater than conventional materials, i.e., a ratio>>5. Acoustic resonant metamaterials are mainly studied at low sound pressure levels (<100dB). However, they are sensitive to increasing the amplitude of acoustic excitation. The studied metamaterial is composed of a compact array of thin single-perforation panels spaced by thin cylindrical air cavities. In a previous study, a mass-spring model was developed for low sound pressure levels. The perforations are modeled by equivalent masses, whereas cavities by equivalent springs. In the perforations, high values of the acoustic velocity lead to an increase in the acoustic resistance of the material. This effect is considered by the Forchheimer parameter in the mass-spring model. To determine this parameter and to study how it is impacted by the metamaterial geometry, the computational fluid dynamic method is used. The mass-spring model is adapted with a nonlinear term. The adapted model agrees well with simulations by finite element method at sound pressure levels up to 140dB.

Profile of Bacterial Resistance in Emergency Wards, Hospitalization, and Intensive Care Units in Mexican Hospitals with the Antimicrobial Stewardship Program

IntroductionBacterial infections are important causes of death. Some reports have shown that the COVID-19 pandemic may have had an impact on drug resistance. AimTo compare the resistance profiles between 2019 and 2020 emergency room, hospitalization non-intensive care units (ICU), and ICU areas in Mexican hospitals. MethodDatabases from 15 hospitals from 8 states in Mexico including susceptibility results for Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa collected from blood, urine, respiratory, and intra-abdominal secretions were analyzed. Different hospital areas were included: emergency room, hospitalization non-ICU, and ICU. The databases were converted using the BacLink2 tool and analyzed using the WHOnet 2022 platform. The percentage of antibiotic resistance was compared for each species and clinical specimen among years (2019 vs 2020) by a chi-square test using the criterion of p<0.05 for statistical significance. ResultsA statistically significant decrease in resistance to imipenem was observed for P. aeruginosa recovered from respiratory specimens in the ICU (55.6% vs 39.3%) and from urine samples from hospitalization non-ICU areas (52.9% vs 37.3%). Also, an increase in resistance was detected in blood isolates from hospitalization non-ICU areas for carbapenems in P. aeruginosa imipenem, (23.3 % vs 54.5%) and meropenem (27.4 % vs 49%) and in E. coli, ertapenem (2.4% vs 10.1%), imipenem (1.9% vs 13.2%), and meropenem (1.6% vs 6.8%). Also, an increase in resistance for imipenem (20.0 % vs 57.5%) and meropenem (17.6% vs 48.7 %) was detected in the emergency room for P. aeruginosa in respiratory isolates. ConclusionA decrease in carbapenem resistance for P. aeruginosa recovered from respiratory specimens in the ICU and from urine samples from hospitalization non-ICU areas was detected. In contrast, an increase in carbapenem resistance was detected for P. aeruginosa in blood isolates from hospitalization non-ICU areas and respiratory isolates from the emergency room. Regarding respiratory samples, a higher resistance for meropenem was detected in 2020 than in 2019 for K. pneumoniae (2.6 vs 10.6%, p = 0.05). These results underline the analysis of AMR in different hospital wards to focus efforts on AMR reduction.

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.

Drag Force on Submerged Flexible Vegetation in an Open‐Channel Flow

AbstractThe movement of submerged flexible vegetation leads to an increase in resistance to the stream flow. In this study, a formula that can directly calculate the drag force on a highly flexible submerged vegetation, called Ceratophyllum, by using the vegetation swaying characteristics and the flow field information in a steady‐uniform open‐channel flow is derived. The drag force on submerged flexible vegetation is characterized by the time‐averaged flow velocity, turbulence intensity, and the additional force arising from the vegetation swaying. Based on the results of the numerical models in the previous studies (Wang et al., 2022a, 2022b, https://doi.org/10.1017/jfm.2022.598, https://doi.org/10.1017/jfm.2022.899), the drag coefficient is determined. It is revealed that the drag coefficient is influenced by a combination of factors, including the flow conditions, and the distribution and movement characteristics of vegetation. The drag coefficient decreases with an increase in velocity and is approximately linearly related to the cubic power of the bulk flow velocity. In the case of an inter‐plant spacing of 0.5 times the initial plant height, the drag coefficient ranges from 10.72 to 2.11, as the Reynolds number varies from 20,000 to 50,000. Besides, the vegetation distribution density and the relative submergence influence the drag coefficient. In this context, the drag coefficient decreases linearly with an increase in the inter‐plant spacing. For the Reynolds number equaling 50,000, the drag coefficient ranges from 2.11 to 2.02, when the inter‐plant spacing varies from 0.5 to 2 times the plant height, and from 2.47 to 1.79, when the flow depth varies from 1.5 to 3 times the plant height.

Cycling Aging in Different State of Charge Windows in Lithium-Ion Batteries with Silicon-Dominant Anodes

Reducing the capacity utilization of silicon-containing anodes and choosing the optimal full-cell voltage window improve the lifetime significantly. In this study, we investigate how different voltage windows affect the aging modes with a common 50% cycling depth. First, the cyclic stability, the anode potentials, and the polarization increase are analyzed for the different voltage windows using 70 wt% microscale silicon anodes and NCA cathodes with a lithium metal reference electrode to investigate the electrode-specific characteristics. Further, the underlying aging modes are quantified in the post-mortem analysis. Finally, the anode thickness increase is quantified using a dilatometer setup for different anode lithiations. In contrast to the literature, the highest voltage window is most beneficial for the lifetime since high anode delithiation potentials and high surface increases are avoided. The anode potential at the end-of-discharge, the charge-averaged full-cell potentials, and the resistance increase are a function of the state of health (SoH). The common underlying main aging mechanism is the loss of lithium inventory, followed by the loss of anode active material. In contrast, the loss of cathode active materials only plays a minor role.

Enhanced Schottky barrier engineering in silver-doped TiO2/p-Si heterojunctions: Insights into electrical behavior and charge carrier dynamics

Heterojunctions were fabricated through the deposition of silver-doped Titanium dioxide (Ag–TiO2) onto p-type crystalline silicon, employing the sol-gel technique. Electrical characterization was conducted with varying Ag concentrations. The investigation revealed that the Schottky barriers at each interface (Ag/TiO2 and Si/Ag), along with the built-in potential at the TiO2/p-Si junction, increase proportionally with the Ag concentration. This observed trend was attributed to the reduction in the TiO2 bandgap due to Ag incorporation, resulting in a concurrent shift in both valence and conduction bands. Consequently, there is a growth of the conduction energy discontinuity and a reduction in the valence one, facilitating hole diffusion while impeding electron transfer across the depletion layer. Furthermore, the introduction of Ag leads to a decrease in both electron and hole concentrations. However, Ag incorporation within the TiO2 matrix manifests as nanoparticles and clusters, resulting in a nonhomogeneous distribution of charge carriers across the sample. Impedance analysis indicates an increase in device resistance and a decrease in effective capacitance.

Antibiofilm and antivirulence potentials of iodinated fmoc-phenylalanine against Staphylococcus aureus

Staphylococcus aureus poses significant risks to public health due to its ability to form biofilm and produce virulence factors, contributing to the increase in antibiotic resistance and treatment complications. This emphasizes the urgent need for novel antimicrobial controls. Based on the premise that halogenation improves antimicrobial efficacy, this study investigated the ability of halogenated phenylalanine to effectively inhibit S. aureus biofilm formation and virulence activities. Among 29 halogenated compounds, Fmoc-4-iodo-phenylalanine (Fmoc-Iodo-Phe) displayed the highest antibiofilm effect against S. aureus, achieving 94.3 % reduction at 50 μg/mL. Microscopic studies confirmed its ability to prevent and disrupt mature biofilms. At 10 μg/mL, Fmoc-Iodo-Phe markedly inhibited virulence factors, such as cell surface hydrophobicity, hemolysin and slime production. It showed low propensity for resistance development and effectively inhibited biofilms formed by methicillin-resistant S. aureus (MRSA) and S. epidermidis, but was inactive against Gram-negative bacteria. Gene expression analysis complemented by molecular docking suggest that Fmoc-Iodo-Phe could target the AgrA quorum sensing cascade due to strong interactions with key residues at its DNA binding sites. Notably, it was non-cytotoxic in Caenorhabditis elegans model and satisfied drug-likeliness criteria based on ADMET prediction. Therefore, our findings position Fmoc-Iodo-Phe as a promising antimicrobial candidate against S. aureus infections, underscoring its potential as an alternative to traditional antibiotics.

Synergistic Effect of Silver Nanoparticles with Antibiotics for Eradication of Pathogenic Biofilms.

The increase in nosocomial multidrug resistance and biofilm-forming bacterial infections led to the search for new alternative antimicrobial strategies other than traditional antibiotics. Silver nanoparticles (AgNP) could be a viable treatment due to their wide range of functions, rapid lethality, and minimal resistance potential. The primary aim of this study is to prepare silver nanoparticles and explore their antibacterial activity against biofilms. AgNPs with specific physicochemical properties such as size, shape, and surface chemistry were prepared using a chemical reduction technique, and then characterized by DLS, SEM, and FTIR. The activity of AgNPs was tested alone and in combination with some antibiotics against MDR Gram-negative and Gram-positive planktonic bacterial cells and their biofilms. Finally, mammalian cell cytotoxicity and hemolytic activity were tested using VERO and human erythrocytes. The findings of this study illustrate the success of the chemical reduction method in preparing AgNPs. Results showed that AgNPs have MIC values against planktonic organisms ranging from 0.0625 to 0.125 mg/mL, with the greatest potency against gram-negative bacteria. It also effectively destroyed biofilm-forming cells, with minimal biofilm eradication concentrations (MBEC) ranging from 0.125 to 0.25 mg/ml. AgNPs also had lower toxicity profiles for the MTT test when compared to hemolysis to erythrocytes. Synergistic effect was found between AgNPs and certain antibiotics, where the MIC was dramatically reduced, down to less than 0.00195 mg/ml in some cases. The present findings encourage the development of alternative therapies with high efficacy and low toxicity.

Central NUCB2/nesfatin-1 signaling ameliorates liver steatosis through suppression of endoplasmic reticulum stress in the hypothalamus

Background & aimsNucleobindin-2 (NUCB2)/nesfatin-1, a signal with recognized anorexigenic and insulin-sensitizing properties in peripheral tissues, is expressed within the hypothalamus. However, the potential involvement of central nesfatin-1 signaling in the pathophysiology of hepatic steatosis remains unknown. This study aimed to determine whether and how central NUCB2/nesfatin-1 plays a role in liver steatosis. MethodsWe generated Nucb2 knockout (Nucb2−/−) rats and administered continuous intracerebroventricular (ICV) nesfatin-1 infusion, while observing its effect on liver steatosis. The molecular mechanism of action of nesfatin-1 was elucidated via proteomics, phosphoproteomics and molecular biology methods. ResultsHerein, we present compelling evidence indicating diminished NUCB2 expression in the hypothalamus of obese rodents. We demonstrated that chronic ICV infusion of nesfatin-1 mitigated both diet-induced obesity and liver steatosis in high-fat diet (HFD)-fed Nucb2−/− rats by regulating hypothalamic endoplasmic reticulum (ER) stress and Akt phosphorylation. Furthermore, we revealed that the increase in hypothalamic insulin resistance (IR) and ER stress induced by tunicamycin infusion or Ero1α overexpression exacerbated hepatic steatosis and offset the favorable influence of central nesfatin-1 on hepatic steatosis. The metabolic action of central nesfatin-1 is contingent upon vagal nerve transmission to the liver. Mechanistically, nesfatin-1 impedes ER stress and interacts with Ero1α to repress its Ser106 phosphorylation. This leads to the enhancement of Akt activity in the hypothalamus, culminating in the inhibition of hepatic lipogenesis. ConclusionsThese findings underscore the importance of hypothalamic NUCB2/nesfatin-1 as a key mediator in the top-down neural mechanism that combats diet-induced liver steatosis.

Vessels and pressures: Update on the management of pulmonary arterial hypertension

Pulmonary hypertension (PH) refers to an abnormal elevation in pulmonary arterial pressure (PAP) under resting conditions. PH is often encountered in patients with chronic heart and lung disease. Rarely, it occurs in the absence of any identifiable heart or lung abnormalities. Under these conditions, the increase in PAP may be caused by diffuse remodeling of the distal pulmonary circulation characterized by an obliterative vasculopathy that leads to a marked increase in pulmonary vascular resistance, progressive right heart failure, and usually death. This disease is referred to as pulmonary arterial hypertension (PAH) and has become the focus of intense basic science and clinical research over the past quarter century. Since 1995, five classes of drugs that encompass more than a dozen specific agents have been developed and approved for the treatment of PAH. The large number of drugs and the myriad forms of pulmonary vascular disease has made the evaluation and treatment of PH an intriguing challenge. This review discusses the most recent definitions of PH and current classification of the pulmonary hypertensive diseases. An overview of the importance and proper approach to diagnosis is provided as well as the impact of patient selection on the approach to management. An evidence-based approach is used to determine how initial therapy is chosen and how additional medications can be used in patients who do not achieve treatment goals. Finally, the results of recently completed clinical trials that evaluated the safety and efficacy of a new class of medications that have been developed to target the underlying pathophysiology of PAH are presented and the potential impact on the management of PAH is discussed. The purpose of this review is to present the reader with an update on the current approach to evaluation and management of PH with an emphasis on PAH.

The In vitro evaluation of in silico-designed synthetic peptides AKVUAM-1 and AKVUAM-2 on human lung fibroblast cell line MRC5 and Mycobacterium tuberculosis isolates

Tuberculosis is a major global health problem caused by Mycobacterium tuberculosis and the increase in drug resistance is driving the need for new treatments. Today, various approaches are being applied in the development of drugs for the treatment of tuberculosis. Computer-aided drug design (CADD) enables the prediction of pharmacological efficacy for potential drug molecules during the design process. Thus, new therapeutic compounds can be developed that are more potent, less toxic and have fewer side effects than existing drugs. In this study, we investigated the in vitro activities of AKVUAM-1 and AKVUAM-2 synthetic peptides designed in silico by computer-aided drug design method to inhibit the interaction between M. tuberculosis outer membrane protein Cpn T and macrophage surface receptor CR-1 and Surfactant D protein. Notably, these synthetic peptides do not show cytotoxic effect on normal lung tissue and do not kill M. tuberculosis directly. The MIC values for AKVUAM-1 were higher than 512 μg/ml for all bacterial strains except IST-16 strain (128 μg/ml). According to our results, AKVUAM-1 and AKVUAM-2 synthetic peptides have the potential to be successful candidates for investigating their potential to block macrophage entry of bacilli as targeted.

Dissociative electrochemical analysis of materials degradation of an anion exchange membrane electrolyser

For anion exchange membrane (AEM) electrolysers, degradation studies provide valuable insights into how individual components degrade. Often, this presents a formidable challenge as each component significantly contributes to overall degradation. Here, we propose a methodology to individually compare the degradation of key components in AEM electrolysers: hydrogen evolution reaction (HER) catalyst, oxygen evolution reaction (OER) catalyst, and the AEM itself. First, to measure the degradation of catalyst-coated substrates (CCS) commonly used in AEM electrolysers, the AEM was replaced with a diaphragm (Zirfon Agfa UTP 500) permeable to OH− ions and stable in alkaline media. Subsequently, a cell with a stable catalytic layer (Nafion-coated Ni-felt substrates) was assembled to focus on membrane degradation with an AEM Sustainion X37-50 Grade 60. Chronopotentiometry and electrochemical impedance spectroscopy (EIS) revealed that the cell with the AEM experienced a threefold increase in ohmic resistance, attributed to the loss of functional groups. Additionally, an ion exchange capacity (IEC) analysis indicated that Sustainion lost approximately 20% of its ion exchange capacity. In contrast, the cell composed of CCS and Zirfon showed lower degradation. EIS data fitting demonstrated increased kinetic-related resistances while the ohmic resistance remained unchanged. This work presents a practical approach for comparing component degradation in AEM electrolysers.

In silico testing to identify compounds that inhibit ClfA and ClfB binding to the host for the formulation of future drugs against Staphylococcus aureus colonization and infection.

Staphylococcus aureus is a highly resistant pathogen. It has multiple virulence factors, which makes it one of the most pathogenic bacteria for humankind. The vast increase in antibiotic resistance in these bacteria is a warning of existing healthcare policies. Most of the available antibiotics are ineffective due to resistance; this situation requires the development of drugs that target specific proteins and are not susceptible to resistance. In this study, we identified a compound that acts as an antagonist of ClfA and ClfB by inhibiting their binding to host cells. The shortlisted compound's binding activity was tested by docking and molecular dynamics during its interaction with proteins. The identified compound has excellent binding energy with both ClfA (-10.11 kcal/mol) and ClfB (-11.11 kcal/mol). The molecular dynamics of the protein and compound were stable and promising for further in vitro and in vivo tests. The performance of our compound was tested and compared with that of the control molecule allantodapsone, which was reported in a previous study as a pan inhibitor of the clumping factor. An ADMET study of our selected compound revealed its reliable drug likeliness. This compound is an ideal candidate for in vitro studies.

Diffusion mechanisms and corrosion resistance of nanostructured ZrN-Cu coating obtained by hybrid HiPIMS-DCMS

Globalisation has brought numerous benefits regarding the cost-effective transportation of goods. Still, the shipping industry faces challenges such as corrosion, biofouling, and restrictions on heavy pollutant products used in paintings. This study proposes a solution using a multifunctional coating based on zirconium nitride and copper nano-structured coating, applying high-power impulse and direct current magnetron sputtering processes (i.e., HiPIMS and DCMS, respectively). The coating’s morphological, structural, and chemical features were analysed using advanced characterisation techniques (SEM, EDX, STEM, SAED and EELS). Potentiodynamic polarisation (PP) and Electrochemical Impedance Spectroscopy (EIS − up to 30 days) were employed to study the corrosion resistance in saline solution (3.5 wt% NaCl). Besides, activated ZrN-Cu exhibited a corrosion rate decrease from ∼ 354 x 10−4 to 52 x 10−4 mm/yr when compared to its inactivated counterpart. Besides, a ∼ 3.5-fold impedance increasing was exhibited by activated ZrN-Cu after 30 days of exposure to saline solution, meaning an increase in corrosion resistance compared to the non-activated ZrN-Cu. SEM micrographs revealed that the copper diffusion in ZrN-Cu can be provoked by a strong oxidising agent (NaOCl) or by an electrical potential. Based on the chartered evidence, a diffusion mechanism is proposed for the biocidal release (Cu) in the obtained ZrN-Cu films. The present study depicts a solution that offers a controlled biocide release and corrosion resistance, opening the possibility of its application in the maritime industry.

Dichloromethane -methanol fraction of Mahonia nepalensis containing Berberine, Jatrorrhizine, and tetrahydroberberine as corrosion inhibitor for mild steel

A potentially superior alternative source of environmentally acceptable corrosion inhibitors for metallic materials is plant extracts. This study reports on the use of compounds separated from Mahonia nepalensis (MN) bark extract as an environmentally friendly corrosion inhibitor for mild steel (MS) in 1 M H2SO4. The organic layer was separated from MN bark extracts and then Berberine, Jatrorrhizine, and Tetrahydroberberine were identified and quantified by Liquid column mass spectroscopy (LC-MS) in dichloromethane (DCM) −Methanol fraction of Mahonia nepalensis. The DCM − Methanol fraction of extract was characterized by Ultra violet − visible spectroscopy (UV–Vis) and Fourier Transform Infrared (FTIR). The DCM-Methanol fractions in 1 M H2SO4 were applied to study corrosion inhibition of MS by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed above 91 % inhibition efficiency (IE) for DCM-Methanol fraction containing 2.12 ppm berberine, jatrorrhizine, and tetrahydroberberine at room temperature indicating that it is an effective and cheap candidate for the corrosion prevention of MS in industry. The potentiodynamic polarization demonstrated a reduction in current density without affecting the reaction mechanism but reduced the hydrogen reduction indicated by suppression in cathodic current. Based on polarization curves and open circuit potential, it exhibited mixed inhibitory behavior. Similarly, EIS analysis revealed a drop in double-layer capacitance accompanied by an increase in charge transfer resistance. EIS and a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) ascertain the adsorption of inhibitor molecules forming a protective layer on the MS surface.

Enhanced thermomechanical fatigue resistance in W10Re alloys: Microstructural and surface engineering approaches

Thermomechanical fatigue of refractory metals is commonly observed in high-temperature environments like first walls and divertors for proposed fusion reactors or X-ray anodes for medical imaging. Typically, alloying with rhenium or optimized microstructures are employed to counteract or delay the detrimental effects of fatigue in tungsten. Additionally, a novel concept is the utilization of surface structures to compensate cyclic thermal stresses. This work aimed to investigate the combination of these approaches, by comparing two W10Re alloys with vastly different microstructures, as well as engineered surface conditions of varying scales. Samples were subjected to thermocyclic fatigue under pulsed electron beam exposure, mimicking the surface temperatures typically encountered in a rotating X-ray anode. Analysis of several in-situ data streams, post-mortem investigations by metallography, and finite element methods revealed the interplay between microstructure and surface modifications. The columnar microstructure exhibited higher resistance to severe surface damage compared to the globular one, linked to the deflection of cracks along grain boundaries and subsequent melting. Coarse structuring was found to partly relieve the surface stresses during thermal cycling, preventing most of the damage accumulation. A full damage relief and performance equivalence between columnar and globular microstructure was achieved by engineering fine-structured surfaces, which led to a ten-fold increase in fatigue resistance over the non-structured condition.

Microwave-assisted synthesis of carbon nanodots from Bombax ceiba leaves for enhanced Tribo-corrosion resistance: An experimental and computational analysis

This study presents a novel method for synthesizing carbon nanodots (BC-CNDs) from Bombax ceiba leaf extract via microwave assistance, yielding cost-effective, biodegradable, and water-soluble nanomaterials. Spectroscopic analysis, including FT-IR, UV–Vis, and fluorescence emission spectrophotometry, revealed the distinctive characteristics of BC-CNDs. Additionally, an anti-corrosive coating (BC-CNDs-C) was formulated by blending BC-CNDs with a plasticizer and binder. Quantitative evaluation of BC-CNDs-C showed an impressive inhibitory rate of 92.55% against corrosion. Electrochemical measurements indicated a notable increase in polarization resistance (Rp values: 1782.2 Ω cm2 for P1 to 4778.3 Ω cm2 for P4) and a decrease in corrosion current density (Icorr values: 0.065 μA/cm2 for P1 to 0.010 μA/cm2 for P4) with the incorporation of BC-CNDs, highlighting their effectiveness in enhancing corrosion resistance. Additionally, structural analyses via scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed the reliability of BC-CNDs-C as a corrosion barrier. This research contributes to the development of sustainable materials for corrosion protection, addressing corrosion-related challenges in various industrial applications.

Prevalence, rate, and predictors of virologic failure among adult HIV-Infected clients on second-line antiretroviral therapy (ART) in Tanzania (2018–2020): a retrospective cohort study

BackgroundAntiretroviral therapy (ART) has been proven to be highly effective in reducing the impact of human immunodeficiency virus (HIV) infection. However, as more people receive initial ART treatment, the risk of developing resistance and eventual treatment failure increases, leading to the need for second-line treatment regimens. Understanding the factors that contribute to virologic failure to second-line ART is crucial in preventing switching to the more expensive and toxic third-line regimens. This study provides information on the prevalence, rate, and predictors of virologic failure (VF) among clients on second-line ART in Tanzania.ResultsWe followed 4718 clients for 15100 person-years (PY) of observations. Of them, 1402 (29.72%) experienced virologic failure at a rate of 92.85 per 1000 PY of observations (95% CI 88.11, 97.84). Factors that were associated with VF included: having a viral load count of ≥ 1000 copies/mL during first-line ART, with a hazard ratio (HR) 4.65 (95% CI 3.57, 6.07), using lopinavir (LPV/r) as a protease inhibitor during second-line ART (HR 4.20 (95% CI 3.12, 7.10), having a CD4 count < 200 cells/mm3 during second-line ART (HR 1.89 (95% CI 1.46, 2.44), and being on ART for 13–35 months (HR 8.22 (95% CI 2.21, 30.61). Paradoxically, having a CD4 count < 200 cells/mm3 during first-line ART treatment was associated with a reduced risk of virologic failure (HR 0.77 (95% CI 0.60, 0.99).ConclusionsIn Tanzania, approximately 30% of adult clients on second-line ART experience VF at a rate of 92.71 per 1000 person-years. This high virologic failure rate underscores the urgent need for targeted interventions, such as enhancing adherence support, optimizing drug regimens, and regular viral load monitoring. These interventions will reduce the need for switching to the more costly and toxic third-line ART therapy and are also crucial for achieving the UNAIDS goal of 95% viral suppression among treated individuals by 2030.