Analysing green supply chain management practices in Brazil’s electrical/electronics industry using interpretive structural modelling

Industries need to adopt the environmental management concepts in the traditional supply chain management. The green supply chain management (GSCM) is an established concept to ensure environment-friendly activities in industry. This paper identifies the relationship of driving and dependence that exists between GSCM practices with regard to their adoption within Brazilian electrical/electronic industry with the help of interpretive structural modelling (ISM). From the results, we infer that cooperation with customers for eco-design practice is driving other practices, and this practice acts as a vital role among other practices. Commitment to GSCM from senior managers and cooperation with customers for cleaner production occupy the highest level.     

Nitroarenes as Antitubercular Agents: Stereoelectronic Modulation to Mitigate Mutagenicity

Nitroarenes are less preferred in drug discovery due to their potential to be mutagenic. However, several nitroarenes were shown to be promising antitubercular agents with specific modes of action, namely, nitroimidazoles and benzothiazinones. The nitro group in these compounds is activated through different mechanisms, both enzymatic and non‐enzymatic, in mycobacteria prior to binding to the target of interest. From a whole‐cell screening program, we identified a novel lead nitrobenzothiazole (BT) series that acts by inhibition of decaprenylphosphoryl‐β‐d ‐ribose 2′‐epimerase (DprE1) of Mycobacterium tuberculosis (Mtb). The lead was found to be mutagenic to start with. Our efforts to mitigate mutagenicity resulted in the identification of 6‐methyl‐7‐nitro‐5‐(trifluoromethyl)‐1,3‐benzothiazoles (cBTs), a novel class of antitubercular agents that are non‐mutagenic and exhibit an improved safety profile. The methyl group ortho to the nitro group decreases the electron affinity of the series, and is hence responsible for the non‐mutagenic nature of these compounds. Additionally, the co‐crystal structure of cBT in complex with Mtb DprE1 established the mode of binding. This investigation led to a new non‐mutagenic antitubercular agent and demonstrates that the mutagenic nature of nitroarenes can be solved by modulation of stereoelectronic properties.     

Synthesis of PEO-based di-block glycopolymers at various pendant spacer lengths of glucose moiety and their in-vitro biocompatibility with MC3T3 osteoblast cells

Di-block copolymers of poly(ethylene oxide) (PEO) and glycopolymers at three different pendant spacer lengths of glucose moiety were synthesized by deacetylation of pendant moieties of 2,3,4,6-tetra-O-acetyl-d-glucopyranosides which were prepared by reversible addition-fragmentation chain-transfer (RAFT) process. The water soluble deacetylated copolymers, PEO-b-poly(acryl-d-glucopyranoside) (PEO-b-PAG, 2a), PEO-b-poly[4′-(acryloxy)butyl-d-glucopyranoside] (PEO-b-PABG, 2b), and PEO-b-poly[6′-(acryloxy)hexyl-d-glucopyranoside] (PEO-b-PAHG, 2c) were characterized in comparison with acetylated copolymers by spectroscopic and gel permeation chromatography methods. In order to assess the biocompatibility of these three di-block copolymers, the adhesion (%), viability (%), and proliferation assays were carried out in MC3T3 cells in-vitro at different concentrations from 10 nM to 1000 μM. Qualitative analysis of cell cytoskeletal organization was obtained by immunostaining with talin and integrin α5. It was clearly indicative of well spreading of cells in the presence of all glycopolymers at lower concentrations but with an increase in the concentration (10 and 100 μM) showed significant change in the cell surface morphologies, despite having good cell adhesion and viability as compared to the control conditions. The use of di-block glycolpolymers at?≤?100 μM of the concentration showed very good osteoblast cells adhesion and viability response; however at higher concentrations (1000 μM) of glycopolymers > 80% of cells lost their viability.     

Experimental Investigation and Simulation of Magnetic Flux Leakage from Metal Loss Defects

Journal of Failure Analysis and Prevention - Magnetic flux leakage (MFL) principle is widely used in detecting defects in cross-country pipelines. The tools based on the MFL techniques termed as...     

An X-ray Radiography Study of the Effect of Thermal Cycling on Damage Evolution in Large-Area Sn-3.5Ag Solder Joints

There is a need for next-generation, high-performance power electronic packages and systems utilizing wide-band-gap devices to operate at high temperatures in automotive and electricity transmission applications. Sn-3.5Ag solder is a candidate for use in such packages with potential maximum operating temperatures of about 200°C. However, there is a need to understand the thermal cycling reliability of Sn-3.5Ag solders subject to such high-temperature operating conditions. The results of a study on the damage evolution occurring in large-area Sn-3.5Ag solder joints between silicon dies and direct bonded copper substrates with Au/Ni-P metallization subject to thermal cycling between 200°C and 5°C are presented in this paper. Interface structure evolution and damage accumulation were followed using high-resolution X-ray radiography, cross-sectional optical and scanning electron microscopies, and X-ray microanalysis in these joints for up to 3000 thermal cycles. Optical and scanning electron microscopy results showed that the stresses introduced by the thermal cycling result in cracking and delamination at the copper–intermetallic compound interface. X-ray microanalysis showed that stresses due to thermal cycling resulted in physical cracking and breakdown of the Ni-P barrier layer, facilitating Cu-Sn interdiffusion. This interdiffusion resulted in the formation of Cu-Sn intermetallic compounds underneath the Ni-P layer, subsequently leading to delamination between the Ni-rich layer and Cu-Sn intermetallic compounds.     

Pre-disaster investment decisions for strengthening a highway network

We address a pre-disaster planning problem that seeks to strengthen a highway network whose links are subject to random failures due to a disaster. Each link may be either operational or non-functional after the disaster. The link failure probabilities are assumed to be known a priori, and investment decreases the likelihood of failure. The planning problem seeks connectivity for first responders between various origin–destination (O–D) pairs and hence focuses on uncapacitated road conditions. The decision-maker's goal is to select the links to invest in under a limited budget with the objective of maximizing the post-disaster connectivity and minimizing traversal costs between the origin and destination nodes. The problem is modeled as a two-stage stochastic program in which the investment decisions in the first stage alter the survival probabilities of the corresponding links. We restructure the objective function into a monotonic non-increasing multilinear function and show that using the first order terms of this function leads to a knapsack problem whose solution is a local optimum to the original problem. Numerical experiments on real-world data related to strengthening Istanbul's urban highway system against earthquake risk illustrate the tractability of the method and provide practical insights for decision-makers.     

Varying relaxation parameters in nonlinear successive overrelaxation

We derive here a generalization to nonlinear problems of the “free steering theorem” of Ostrowski on sufficient conditions for convergence of linear SOR with varying relaxation parameters.     

Modulating functional loop movements: the role of highly conserved residues in the correlated loop motions

Loop flexibility in enzymes plays a vital role in correctly positioning catalytically important residues. This strong relationship between enzyme flexibility and function provides an opportunity to engineer new substrates and inhibitors. It further allows the design of site-directed mutagenesis experiments to explore enzymatic activity through the control of flexibility of a functional loop. Earlier, we described a novel mechanism in which a small loop triggers the motions of a functional loop in three enzymes (beta-1,4-galactosyltransferase, lipase, and enolase) unrelated in sequence, structure, or function. Here, we further address the question of how the interactions between various flexible loops modulate the movements of the functional loop. We examine beta-1,4-galactosyltransferase as a model system in which a Long loop undergoes a large conformational change (moves in space up to 20 A) upon substrate binding in addition to a small loop (Trp loop) that shows a considerably smaller conformational change. Our molecular-dynamics simulations carried out in implicit and explicit solvent show that, in addition to these two loops, two other neighboring loops are also highly flexible. These loops are in contact with either the Long loop or the Trp loop. Analysis of the covariance of the spatial displacement of the residues reveals that coupled motions occur only in one of these two loops. Sequence analysis indicates that loops correlated in their motions also have highly conserved residues involved in the loop-loop interactions. Further, analysis of crystal structures and simulations in explicit water open the possibility that the Trp loop that triggers the movement of the Long loop in the unbound conformation may also play the same role in the substrate-bound conformation through its contact with the conserved and correlated third loop. Our proposition is supported by the observation that four of the five conserved positions in the third loop are at the interface with the Trp loop. Evolution appears to select residues that drive the functional Long loop to a large conformational change. These observations suggest that altering selected loop-loop interactions might modulate the movements of the functional loop.