Bacteria-Responsive Self-Assembly of Antimicrobial Peptide Nanonets for Trap-and-Kill of Antibiotic-Resistant Strains

Bacterial trapping using nanonets is a ubiquitous immune defense mechanism against infectious microbes. These nanonets can entrap microbial cells, effectively arresting their dissemination and rendering them more vulnerable to locally secreted microbicides. Inspired by this evolutionarily conserved anti-infective strategy, a series of 15 to 16 residue-long synthetic β-hairpin peptides is herein constructed with the ability to self-assemble into nanonets in response to the presence of bacteria, enabling spatiotemporal control over microbial killing. Using amyloid-specific K114 assay and confocal microscopy, the membrane components lipoteichoic acid and lipopolysaccharide are shown to play a major role in determining the amyloid-nucleating capacity as triggered by Gram-positive and Gram-negative bacteria respectively. These nanonets displayed both trapping and killing functionalities, hence offering a direct improvement from the trap-only biomimetics in literature. By substituting a single turn residue of the non-amyloidogenic BTT1 peptide, the nanonet-forming BTT1-3A analog is produced with comparable antimicrobial potency. With the same sequence manipulation approach, BTT2-4A analog modified from BTT2 peptide showed improved antimicrobial potency against colistin-resistant clinical isolates. The peptide nanonets also demonstrated robust stability against proteolytic degradation, and promising in vivo efficacy and biosafety profile. Overall, these bacteria-responsive peptide nanonets are promising clinical anti-infective alternatives for circumventing antibiotic resistance.     

Plasma spheroidization of nickel powders in a plasma reactor

Thermal spray coatings of surfaces with metal, alloy and ceramic materials for protection against corrosion, erosion and wear is an intense field of research. The technique involves injection of the powder into a plasma flame, melting, acceleration of the powder particles, impact and bonding with the substrate. Feedstock powders of metals, alloys and ceramics for thermal spray applications have to meet several requirements. Particle shape, size and its distribution, powder flow characteristics and density are the important factors to be considered in order to ensure high spray efficiency and better coating properties. For smooth and uniform feeding of powders into plasma jet, the powder particles have to be spherical in shape. High temperatures and steep temperatures present in thermal plasma is exploited to spheroidize particles in the present investigation. Nickel powder particles in the size range from 40–100 μm were spheroidized using plasma processing. SEM and optical micrographs showed spherical shape of processed particles.     

Investigation on microstructure and tensile behaviour of stir cast LM13 aluminium alloy reinforced with copper coated short steel fibers using response surface methodology

Copper coated steel fibers reinforced LM13 aluminium alloy composites have been prepared using stir casting process. Experiments have been designed using response surface methodology by varying wt% of reinforcement (0–10), stirrer speed (350–800 rpm) and pouring temperature (700–800 °C). Microstructure, tensile strength and fracture surface of composites have been investigated. Analysis of variance, significance test and confirmation tests have been performed and regressions models have been developed to predict the tensile strength of composites. Response surface plots reveal that tensile strength of composites increases with increasing wt% of copper coated steel fibers reinforcement up to 6 wt%. Further increase in wt% of steel fibers decreases the tensile strength of composites. However tensile strength of composites increases with increasing stirrer speed due to the uniform and homogeneous dispersion of steel fibers in matrix. Optimum stir cast process parameters for obtaining higher tensile strength are found to be 5.9 wt% of reinforcement, 753 °C pouring temperature and stirrer speed of 633 rpm. Fracture mechanism is dominated by steel fiber pullouts in composites with higher wt% of reinforcement and dimples are observed in the surface of composites containing lower levels of wt% of reinforcement.     

Workflow balancing strategies in parallel machine scheduling

Workflow balancing on a shop floor helps to remove bottlenecks present in the manufacturing system. Workflow refers to the total time during which the work centres are busy. Idle time is not taken into account when calculating workflow. Earlier researchers have not specified the method for jobs to be executed in parallel in order to balance the workflow to each machine. In many manufacturing environments, multiple processing stations are used in parallel to obtain adequate capacity. In parallel machine scheduling there are m machines to which n jobs are to be assigned based on different priority strategies. The procedure is based on the idea of workload balancing and on balancing the workload among machines. In this paper, workflow and workload are assumed to have the same meaning. A machine with the lowest workflow is selected for assignment of a new job from the list of unfinished jobs. Different priority strategies are followed for the selection of jobs. Three different strategies are considered, namely random (RANDOM), shortest processing time (SPT) and longest processing time (LPT) for the selection of jobs for workflow balancing. The relative percentage of imbalance (RPI) is adopted among the parallel machines to evaluate the performance of these strategies in a standard manufacturing environment. The LPT rule shows better performance for the combination of larger job sizes and higher number of work centres or machines. A computer program was coded for validation in a standard manufacturing environment on an IBM/PC compatible system in the C++ language.     

Bioecology of macrobenthic communities in the microtidal monsoonal Kodungallur–Azhikode Estuary,southwest coast of India

A comprehensive study of the macrobenthic communities in the Kodungallur–Azhikode Estuary (KAE) was conducted during 2009–2011 period. A total of 18,846 organisms were collected, with 60% being malacostracans, followed by polychaetes (20%), molluscs (9%) and ‘others’ group (11%). A total of 79 species in 71 genera belonging to 49 families were identified, with 33 spp. being polychaetes, 26 spp. being malacostracans, 11 spp. being molluscs and 9 spp. being in the ‘others’ group. A single species of opportunistic amphipod (Americorophium triaeonyx) comprised more than 62.05% of the total numerical abundance of macrobenthos. The other dominant species were Obelia bidentata, Arcuatula senhousia, Cirolana fluviatilis, Prionospio cirrifera and Capitella sp. Canonical correspondence analysis (CCA) results indicated environmental parameters such as water column salinity, turbidity, sediment Eh, substratum type, chlorophyll‐a concentration, depth and organic matter in sediment were the significant factors influencing the distribution of macrobenthic species in the KAE. The present study provides baseline information for future KAE benthic studies.     

Anaerobic co-digestion of hazardous tannery solid waste and primary sludge: biodegradation kinetics and metabolite analysis

Generation of solid waste is inherent to manufacture of leather from skin and hide. Solid wastes generated at various unit operations of the tanning process considerably vary in quantity and composition. Fleshing is a type of animal tissue waste generated during the preparatory leather processing stage in relatively larger quantities as compared to other types of solid waste in the tanning industry. Fleshing mainly contains fat and protein and residual chemicals such as lime and sulphide used in the ‘unhairing’ process of beam house operation. Another type of solid waste in tanning industry which requires safe disposal is the primary sludge from tannery wastewater treatment plant. This study shows that both fleshing and primary sludge contains a significant quantity of volatile solids amenable for biodegradation. Different proportions of waste fleshing and primary sludge were subjected to anaerobic digestion. The studies were carried out in a laboratory scale reactor with an aim of developing an appropriate technology for recovery of bioenergy from the waste and subsequently ensure their safe disposal. Volatile solid destruction between 41 and 52%, specific gas production between 0.419 and 0.635 l/g volatile solids feed and methane yield between 71 and 77% were achieved. Further, the biomethanation potential of animal fleshing and substrate specific kinetics of the reaction process were also examined.     

Temperature dependence of the dielectric response of BaZrO3 by immittance spectroscopy

Electrical measurements using AC immittance spectroscopic technique over the temperature range of 25-300°C, on sintered compacts of pure BaZrO₃ and those containing 5 wt.% BaSnO₃ sintered in the temperature range of 1600-1700°C for up to 12 h are reported. Data analyses revealed that the capacitance and the derived dielectric constant remained invariant over more than three decades of frequency in the kilo to megahertz regime. Typically, the average dielectric constant was 15 and the TCK values were P3 and P186 ppm/°C for pure and 5 wt.% BaSnO₃-added BaZrO₃, respectively, in the range 25-300°C.     

Crystal growth,structure, surface,optical, thermal,mechanical, magnetic,electrical investigations on cesium sulphate-doped 4-methoxyaniline: a single crystal for NLO and antimicrobial applications

A new single crystal of cesium sulphate-doped 4-methoxyaniline (CS-4MOA) was obtained by the solvent evaporation approach. XRD manifests that the CS-4MOA crystallizes in orthorhombic crystal structure. The existence of several functional groups in the CS-4MOA crystal is affirmed by FTIR analysis. SEM-EDAX analysis was performed to examine the surface morphology and the composition of CS-4MOA sample. Ultraviolet–visible spectral study validates the transparency of CS-4MOA in the region of 330–1100 nm. The thermal steadiness of the CS-4MOA crystal was examined using TG/DTA, which revealed that it was stable up to 88 °C. The mechanical stability of CS-4MOA crystal was assessed through Vickers microhardness analysis. VSM analysis was used to evaluate the magnetic behaviour of the CS-4MOA crystal. The electrical characteristics of the CS-4MOA were investigated by impedance study for various temperatures. The NLO parameters of CS-4MOA were computed by Z-scan technique. The existence of second order nonlinear optical susceptibility in CS-4MOA was confirmed by the SHG investigation. Additionally, antimicrobial activity of CS-4MOA was performed against bacterial strains and fungal pathogen for medicinal applications.