In this study, a three-dimensional single channel is numerically modeled to simulate the polymer electrolyte fuel cell (PEFC) with a homogeneous and inhomogeneous gas diffusion layer (GDL). The ...influence of interfacial contact resistance (ICR) between GDL and current collector ribs (GDL|CC) is also studied. In the present study, GDL is considered as a single component (homogeneous) in one case and inhomogeneous with varying electrical and flow properties to illustrate the inhomogeneity in another case. The inhomogeneity in GDL is primarily caused by localized deformation due to non-uniform contact pressure during fuel cell assemblies. The consideration of ICR is observed to have a significant effect on both the ohmic and mass transport regions of the polarization curve. Inhomogeneous GDL with ICR, considered close to a practical scenario, shows a ∼7% drop in performance evaluation at 0.3V. The study reveals increased consumption of reactants at higher current loads when ICR is assumed negligible. This study examines the effects of homogeneous GDL, inhomogeneous GDL, and the impact of ICR on the distributions of reactant concentration, water concentration, temperature, current density, and polarization curve in PEFC. This study presents the practical aspects of PEFC considering inhomogeneous GDL electrical and flow properties.
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•The inhomogeneity of GDL electrical and flow properties are explored.•Slight variation in performance is predicted with GDL inhomogeneity in the absence of ICR.•The effect of inhomogeneous GDL with ICR led the performance to reduce overall by ∼7%.•GDL inhomogeneity has a significant influence on reactants and various transport characteristics.
A three-dimensional single-flow channel computational model is used to investigate the performance characteristics of polymer electrolyte fuel cells (PEFC). The combined influence of non-uniform ...interfacial contact resistance (ICR) and inlet relative humidity (RH), along with the heterogeneous flow properties of the gas diffusion layer (GDL) on the PEFC performance is evaluated. The study considers combinations of full and partial humidification of anode and cathode reactants. Results reveal heterogeneous GDL with non-uniform ICR distribution results in a slight ∼4.4% reduction in current density at 0.3V compared to the homogeneous case. However, under same electrical/flow heterogeneities, the current density is observed to increase by ∼19% to ∼1.3A/cm2 under fully humidified anode and partially humidified cathode (i.e., RHa|RHc = 100%|60%) as compared to ∼1.1A/cm2 under symmetric RHa|RHc = 100%|100%. Interesting observations are made on the temperature distribution and cathodic water fractions. The variation in anodic inlet humidity is observed to have no impact on temperature distribution in the membrane, whereas variation in cathodic inlet humidity is effective in reducing the temperature in the channel regime with a 4K (kelvin) difference among all the cases. It is noted here that the overpotential map is not an indicator for performance loss, at least at full inlet humidity. This parameter is observed to depend on water concentration in the cathode. The study provides a detailed analysis of the distribution of reactant mass fraction, water concentration, current density, temperature, cathodic overpotential, and cell performance for all the simulated cases.
•Effect of electrical/flow heterogeneity of GDL under different inlet humidification is simulated.•Heterogeneity lead to ∼4.4% reduction in current density (from ∼1.2A/cm2 to ∼1.15A/cm2) under full humidification.•∼19% increase in current density (from ∼1.1A/cm2 to ∼1.3A/cm2) is observed with RHa.|RHc = 100%|60%•Temperature distribution in membrane is dependent function of cathode inlet humidity.•Overpotential is independent indicator of PEFC performance variation.
The functioning of proteins requires highly specific dynamics, which depend critically on the details of how amino acids are packed. Hinge motions are the most common type of large motion, typified ...by the opening and closing of enzymes around their substrates. The packing and geometries of residues are characterized here by graph theory. This characterization is sufficient to enable reliable hinge predictions from a single static structure, and notably, this can be from either the open or the closed form of a structure. This new method to identify hinges within protein structures is called PACKMAN. The predicted hinges are validated by using permutation tests on B-factors. Hinge prediction results are compared against lists of manually curated hinge residues, and the results suggest that PACKMAN is robust enough to reproduce the known conformational changes and is able to predict hinge regions equally well from either the open or the closed forms of a protein. A group of 167 protein pairs with open and closed structures has been investigated Examples are shown for several additional proteins, including Zika virus nonstructured (NS) proteins where there are 6 hinge regions in the NS5 protein, 5 hinge regions in the NS2B bound in the NS3 protease complex and 5 hinges in the NS3- helicase protein. Results obtained from this method can be important for generating conformational ensembles of protein targets for drug design. PACKMAN is freely accessible at (https://PACKMAN.bb.iastate.edu/).
Overlapping hinge positions in inorganic phosphatase pdb: 1K20 (blue, closed) and 1K23 (gray, open). Display omitted
•Protein packing is used to identify hinge locations in protein structures.•Works well for any conformational state, open/closed, with hinge loci overlapping.•Useful for drug design to develop an ensemble of conformations.•Useful for studying the global motions and molecular mechanisms of any structure.•Tested and applied to over 300 structures, including Zika virus proteins.
For several decades, point-of-care technology (POCT) has proven its potential regarding swift and cost-efficient detection of analytes. Lateral flow assay is a highly popular POC technology that ...needs improvisation to increase its sensitivity, cost effectiveness and quantification so that it becomes more user friendly and affordable technology. In this context, the present study has investigated the use of aptamers and nanozymes together for the first time in developing an Aptamer-nanozyme lateral flow assay (ALFA). The present study uses a specific aptamer for CA125 as capture reagent and peroxidase mimetic gold nanoparticles as label for detection of CA125 in human serum through developed competitive ALFA. The assay was specific and has a limit of detection of 5.21 U/mL. The ALFA test was in house validated for its precision, recovery and showed a significant correlation with established CA125 chemiluminiscent ELISA with P-value<0.0001. In summary, this assay quantitatively detects an analyte by using an aptamer and peroxidase mimetic gold nanoparticles that ensures circumventing the use of antibodies and incorporating enzyme mimetic activity in assay systems.
•Aptamer-gold nanozyme Lateral flow assay (ALFA) for CA125.•Competitive ALFA with limit of detection 5.21 U/mL.•Peroxidase mimetic gold nanoparticles used as nanozyme.•Specific aptamers for CA125 used as capture reagent.•ALFA correlated well with established CA125 ELISA.
A novel metaheuristic called Chaotic Marine Predators Algorithm (CMPA) is proposed and investigated for the optimization of engineering problems. CMPA integrates the exploration merits of the ...recently proposed Marine Predators Algorithm (MPA) with the chaotic maps exploitation capabilities. Several chaotic maps were applied in the proposed CMPA to govern MPA parameters that eventually led to controlled exploration and exploitation of search. This study makes an initial attempt to explore and employ CMPA in decoding complex and challenging design and manufacturing problems. For performance evaluation of the proposed algorithm, CEC 2020 numerical problems having different dimensions and five widely adopted constrained design problems were solved. For all problems, both qualitative and qualitative results are examined and discussed. Moreover, two case studies of multi-pass turning were examined by the proposed CMPA algorithm to optimize the cutting operation with a minimum cost of production per unit objective. Furthermore, the suggested CMPA algorithm has been investigated for solving a real-world structural topology optimization problem. Statistical analysis is performed, and the results of CMPA are compared with twelve distinguished algorithms. Outcomes of the proposed variant algorithm on the benchmarks demonstrate its significantly improved performance relative to other optimizers including a variant of MPA and two state-of-the-art IEEE CEC competitions winners algorithms. Findings from the manufacturing process exhibit CMPA proficiency in solving arduous real-world design problems.
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•A novel Chaotic Marine Predators Algorithm is developed.•Theoretical and numerical comparisons are extensively investigated.•The results show the merits of the proposed hybrid method used in solving the real-world case studies.
The paper describes biogenic synthesis of silver nanoparticles (AgNPs) using
Adhatoda vasica
leaf extracts at room temperature. The prepared AgNPs were characterized by UV–visible spectroscopy, ...Fourier-transform infrared spectroscopy, powder X-ray diffraction, Energy dispersive X-ray (EDX), High Resolution Transmission Electron Microscope, Scanning Electron Microscopy and Thermogravimetric analyser. The bio reduction method is devoid of any toxic chemicals, organic solvents, and external reducing, capping and stabilizing agent. The synthesized AgNPs had spherical shape with particle size ranging between 3.88 and 23.97 nm and had face centered cubic structure. UV–visible spectral analysis confirmed the formation of AgNPs with a characteristic surface plasmon resonance band at 419 nm. The EDX pattern revealed the presence of elemental Ag in AgNPs. The prepared AgNPs were used for degradation of Amaranth, Allura red and Fast green in aqueous medium, with ≥ 92.6% efficiency within 15 min using 5 mg of AgNPs. The optical bandgap, Eg value of 2.26 eV for AgNPs was found to be effective for rapid photocatalytic degradation of all the three dyes. The degradation process was observed to follow pseudo first order kinetics.
Abstract
Summary
A new dynamic community identifier (DCI) is presented that relies upon protein residue dynamic cross-correlations generated by Gaussian elastic network models to identify those ...residue clusters exhibiting motions within a protein. A number of examples of communities are shown for diverse proteins, including GPCRs. It is a tool that can immediately simplify and clarify the most essential functional moving parts of any given protein. Proteins usually can be subdivided into groups of residues that move as communities. These are usually densely packed local sub-structures, but in some cases can be physically distant residues identified to be within the same community. The set of these communities for each protein are the moving parts. The ways in which these are organized overall can aid in understanding many aspects of functional dynamics and allostery. DCI enables a more direct understanding of functions including enzyme activity, action across membranes and changes in the community structure from mutations or ligand binding. The DCI server is freely available on a web site (https://dci.bb.iastate.edu/).
Supplementary information
Supplementary data are available at Bioinformatics online.
Graphical Abstract
Three communities for Zika virus NS5 protein (PDB ID: 5M2Z). Each color represents a unique community with its motions.
Studies on host-pathogen interaction have identified human ACE2 as a host cell receptor responsible for mediating infection by coronavirus (COVID-19). Subsequent studies have shown striking ...difference of allele frequency among Europeans and Asians for a polymorphism rs2285666, present in
. It has been revealed that the alternate allele (TT-plus strand or AA-minus strand) of rs2285666 elevate the expression level of this gene upto 50%, hence may play a significant role in SARS-CoV-2 susceptibility. Therefore, we have first looked the phylogenetic structure of rs2285666 derived haplotypes in worldwide populations and compared the spatial frequency of this particular allele with respect to the COVID-19 infection as well as case-fatality rate in India. For the first time, we ascertained a significant positive correlation for alternate allele (T or A) of rs2285666, with the lower infection as well as case-fatality rate among Indian populations. We trust that this information will be useful to understand the role of
in COVID-19 susceptibility.
More than one and a half years have elapsed since the commencement of the coronavirus disease 2019 (COVID-19) pandemic, and the world is struggling to contain it. Being caused by a previously unknown ...virus, in the initial period, there had been an extreme paucity of knowledge about the disease mechanisms, which hampered preventive and therapeutic measures against COVID-19. In an endeavor to understand the pathogenic mechanisms, extensive experimental studies have been conducted across the globe involving cell culture-based experiments, human tissue organoids, and animal models, targeted to various aspects of the disease,
, viral properties, tissue tropism and organ-specific pathogenesis, involvement of physiological systems, and the human immune response against the infection. The vastly accumulated scientific knowledge on all aspects of COVID-19 has currently changed the scenario from great despair to hope. Even though spectacular progress has been made in all of these aspects, multiple knowledge gaps are remaining that need to be addressed in future studies. Moreover, multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants have emerged across the globe since the onset of the first COVID-19 wave, with seemingly greater transmissibility/virulence and immune escape capabilities than the wild-type strain. In this review, we narrate the progress made since the commencement of the pandemic regarding the knowledge on COVID-19 mechanisms in the human body, including virus-host interactions, pulmonary and other systemic manifestations, immunological dysregulations, complications, host-specific vulnerability, and long-term health consequences in the survivors. Additionally, we provide a brief review of the current evidence explaining molecular mechanisms imparting greater transmissibility and virulence and immune escape capabilities to the emerging SARS-CoV-2 variants.
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