Green synthesis of anisotropic gold nanoparticles using hordenine and their antibiofilm efficacy against Pseudomonas aeruginosa

Pseudomonas aeruginosa is a notorious pathogen that causes biofilm aided infections in patients with cystic fibrosis and burn wounds, resulting in significant mortality in immunocompromised individuals. This study reports a novel one‐step biosynthesis of gold nanoparticles using phytocompound, hordenine (HD), as a reducing and capping agent. The synthesis of the anisotropic hordenine‐fabricated gold nanoparticles (HD‐AuNPs) with an average particle size of 136.87 nm was achieved within 12 h of incubation at room temperature. Both HD and HD‐AuNPs exhibited significant antibiofilm activity against P. aeruginosa PAO1, although greater biofilm inhibition was observed for the nanoparticles as compared to hordenine alone. In the microtitre plate assay and tube method, the nanoparticles significantly inhibited the biofilm formation by 73.69 and 78.41%, respectively. The exopolysaccharide production by the test pathogen was arrested by 68.46% on treatment with the nanoparticles. Further, the effect of HD and HD‐AuNPs on the biofilm architecture of P. aeruginosa was revealed by light and confocal laser‐scanning microscopy micrographs. The overall results of this study suggested the synergistic antibiofilm effect of AuNPs and HD for the treatment of chronic bacterial infections caused by biofilms forming pathogens.Inspec keywords: molecular biophysics, biochemistry, gold, nanoparticles, nanofabrication, microorganisms, organic compounds, particle size, nanobiotechnologyOther keywords: green synthesis, anisotropic gold nanoparticles, hordenine, antibiofilm efficacy, Pseudomonas aeruginosa, pathogen, cystic fibrosis, burn wounds, one‐step biosynthesis, phytocompound, reducing agent, capping agent, particle size, microtitre plate assay, tube method, confocal laser‐scanning microscopy micrographs, Au     

Stabilization of 2D nonsymmetric half-plane digital filters using the concept of reciprocity

In this paper, the concept of reciprocity for two-dimensional (2D) quarter plane (QP) filters are extended to stabilize 2D nonsymmetric half-plane (NSHP) filters. In general the stabilization of NSHP filters is done by transforming NSHP arrays into QP arrays using mapping theorems. The concept of reciprocity is applied directly without any mapping to stabilize a class of 2D NSHP filters which are otherwise unstable when all singularities lie within the unit bicircle. It is shown that the magnitude spectrum of the stabilized 2D NSHP filter is identical to the magnitude spectrum of the original unstable filter. The proposed stabilization method is simple as compared to two other popular stabilization techniques in the literature, the double planar least squares inverse (DPLSI) and 2D discrete Hilbert transform (2D DHT).     

Comparison of silver-ion high-performance liquid chromatographic quantification of free and methylated conjugated linoleic acids

Silver-ion high-performance liquid chromatography was used to fractionate a mixture of conjugated linoleic acid (CLA) isomers (as the free fatty acids, CLAFFA) in commercial CLA mixtures and biological samples. Due to the unchanged retention mechanism, it was assumed that the elution order of the isomers remained the same as that of methyl esters separated on the same column. The most abundant isomers, cis/trans 10,12-18:2 and cis/trans 9,11-18:2, were separated better as free acids on a single column than in the methyl ester form. Quantification of the CLA standard was used as the reference profile to evaluate different methylation methods commonly used to prepare CLA methyl esters for quantitation. Acid- and vuigi base-catalyzed derivatization methods resulted in CLA intraisomerization and losses in total conjugated dienes content. Acid (HCl and BF₃) methylations significantly elevated the level of trans,trans isomers and significantly reduced the cis/trans isomers. Base methylation, tetramethylguanidine/methanol, resulted in loss of trans,trans isomers, and a substantial loss of total underivatized conjugated dienes. Other catalysts such as the trimethylsilyldiazomethane produced additional peaks of unidentified artifacts. The analysis of CLAFFA appears to provide more accurate quantification of CLA isomers in commercial and biological samples.     

MICROCOUPLER为高温应用提升功耗性能

光耦合器是具有绝缘安全性及在输入和输出之间实现电气信号隔离功能的器件，其绝缘和噪声抑制特性来自于采用的机械结构和材料。     

Dynamic clustering approach with ACO-based mobile sink for data collection in WSNs

Enhancing the network lifetime of wireless sensor networks is an essential task. It involves sensor deployment, cluster formation, routing, and effective utilization of battery units. Clustering and routing are important techniques for adequate enhancement of the network lifetime. Since the existing clustering and routing approaches have high message overhead due to forwarding collected data to sinks or the base station, it creates premature death of sensors and hot-spot issues. The objective of this study is to design a dynamic clustering and optimal routing mechanism for data collection in order to enhance the network lifetime. A new dynamic clustering approach is proposed to prevent premature sensor death and avoid the hot spot problem. In addition, an Ant Colony Optimization (ACO) technique is adopted for effective path selection of mobile sinks. The proposed algorithm is compared with existing routing methodologies, such as LEACH, GA, and PSO. The simulation results show that the proposed cluster head selection algorithm with ACO-based MDC enhances the sensor network lifetime significantly.

     

Performance evaluation of sensor deployment using optimization techniques and scheduling approach for K-coverage in WSNs

In the wireless sensor networks, sensor deployment and coverage are the vital parameter that impacts the network lifetime. Network lifetime can be increased by optimal placement of sensor nodes and optimizing the coverage with the scheduling approach. For sensor deployment, heuristic algorithm is proposed which automatically adjusts the sensing range with overlapping sensing area without affecting the high degree of coverage. In order to demonstrate the network lifetime, we propose a new heuristic algorithm for scheduling which increases the network lifetime in the wireless sensor network. Further, the proposed heuristic algorithm is compared with the existing algorithms such as ant colony optimization, artificial bee colony algorithm and particle swarm optimization. The result reveals that the proposed heuristic algorithm with adjustable sensing range for sensor deployment and scheduling algorithm significantly increases the network lifetime.     

Ferulic acid encapsulated chitosan‐tripolyphosphate nanoparticles attenuate quorum sensing regulated virulence and biofilm formation in Pseudomonas aeruginosa PAO1

Pseudomonas aeruginosa is an opportunistic nosocomial pathogenic microorganism causing majority of acute hospital‐acquired infections and poses a serious public health concern. The persistence of bacterial infection can be attributed to the highly synchronised cell‐to‐cell communication phenomenon, quorum sensing (QS) which regulates the expression of a number of virulence factors and biofilm formation which eventually imparts resistance to the conventional antimicrobial therapy. In this study, the anti‐quorum sensing and anti‐biofilm potential of ferulic acid encapsulated chitosan‐tripolyphosphate nanoparticles (FANPs) was investigated against P. aeruginosa PAO1 and compared with native ferulic acid. Dynamic light scattering and transmission electron microscopic analysis confirmed the synthesis of FANPs with mean diameter of 215.55 nm. FANPs showed significant anti‐quorum sensing activity by downregulating QS‐regulated virulence factors. In addition, FANPs also significantly attenuate the swimming and swarming motility of P. aeruginosa PAO1. The anti‐biofilm efficacy of FANPs as compared to native ferulic acid was established by light and confocal laser scanning microscopic analysis. The promising results of FANPs in attenuating QS highlighted the slow and sustained release of ferulic acid at the target sites with greater efficacy suggesting its application towards the development of anti‐infective agents.Inspec keywords: microorganisms, nanofabrication, nanoparticles, nanomedicine, light scattering, cellular biophysics, drugs, antibacterial activity, drug delivery systems, filled polymers, materials preparationOther keywords: size 215.55 nm, ferulic acid encapsulated chitosan‐tripolyphosphate nanoparticles, dynamic light scattering, QS‐regulated virulence factors, cell‐to‐cell communication phenomenon, nosocomial pathogenic microorganism, anti‐quorum sensing activity, Pseudomonas aeruginosa PAO1, anti‐infective agents, confocal laser scanning microscopic analysis, anti‐biofilm efficacy, transmission electron microscopic analysis, native ferulic acid, FANPs, anti‐biofilm potential, conventional antimicrobial therapy, bacterial infection, acute hospital‐acquired infections, biofilm formation