Defect centres and thermoluminescence in CaSO4:Dy,Ag phosphor

The defect centres formed in the TL phosphor CaSO4:Dy,Ag are studied using the technique of Electron Spin Resonance. The Ag co-doped phosphor exhibits three glow peaks around 130, 220 and 375 degrees C in contrast with the two glow peaks observed in the CaSO4:Dy phosphor at 130 and 220 degrees C at a gamma ray dose of 1Gy. ESR studies show that the additional peak at 375 degrees C correlates with a Ag2+ centre formed due to gamma irradiation and observable only below -170 degrees C. The Ag2+ centre is characterised by an axial g-tensor with principal values g(parallel) = 2.38 and g(perpendicular) = 2.41. ESR studies further indicate that the precursor to a centre observable at low temperature (-170 degrees C) appears to act as the recombination centre for the TL peak at 375 degrees C; this radical is characterised by the g-values g(parallel) = 2.0023 and g(perpendicular) = 2.0038 and is assigned to SO3- radical. It is observed that there is more incorporation of Ag in the CaSO4:Dy system as compared with that in pure CaSO4 system.     

ADYTIA: Adaptive and Dynamic TCP Interface Architecture for heterogeneous networks

Due to the widespread popularity and usage of Internet of things (IoT)‐enabled devices, there is an exponential increase in the data traffic generated from these IoT devices. Most of these devices communicate with each other using heterogeneous links having constraints such as latency, throughput, and interference from concurrent transmissions. This results in an extra burden on the underlying communication infrastructure to manage the traffic within these constraints between source and destination. However, most of the existing applications use different Transmission Control Protocol (TCP) variants for traffic management between these devices and are dependent on the stage of the sender, irrespective of the application types and link characteristics. Each operating system (OS) has different TCP variant for all applications, irrespective of path characteristics. Hence, a single TCP variant cannot select the best suitable link, which results in degradation in throughput compared to the existing default. Moreover, it cannot use the full capacity of the available link for different applications and network links, especially in heterogeneous network such as IoT. To cope up with these challenges, in this paper, we propose an Adaptive and Dynamic TCP Interface Architecture (ADYTIA). ADYTIA allows the usage of different TCP variants based on application and link characteristics, irrespective of the physical links of the entire path. It allows the usage of different TCP variants based on their design principle across heterogeneous technologies, platforms, and applications. ADYTIA is implemented on NS‐2 and Linux kernel for real testbed experiments. Its ability to select the best suitable TCP variant results in 20% to 80% improvement in throughput compared with the existing default and single TCP variant on Linux and Windows.     

Recent Progress on Microfine Design of Metal–Organic Frameworks: Structure Regulation and Gas Sorption and Separation

Metal–organic frameworks (MOFs) have emerged as an important and unique class of functional crystalline hybrid porous materials in the past two decades. Due to their modular structures and adjustable pore system, such distinctive materials have exhibited remarkable prospects in key applications pertaining to adsorption such as gas storage, gas and liquid separations, and trace impurity removal. Evidently, gaining a better understanding of the structure–property relationship offers great potential for the enhancement of a given associated MOF property either by structural adjustments via isoreticular chemistry or by the design and construction of new MOF structures via the practice of reticular chemistry. Correspondingly, the application of isoreticular chemistry paves the way for the microfine design and structure regulation of presented MOFs. Explicitly, the microfine tuning is mainly based on known MOF platforms, focusing on the modification and/or functionalization of a precise part of the MOF structure or pore system, thus providing an effective approach to produce richer pore systems with enhanced performances from a limited number of MOF platforms. Here, the latest progress in this field is highlighted by emphasizing the differences and connections between various methods. Finally, the challenges together with prospects are also discussed.     

Exploitability prediction of software vulnerabilities

The number of security failure discovered and disclosed publicly are increasing at a pace like never before. Wherein, a small fraction of vulnerabilities encountered in the operational phase are exploited in the wild. It is difficult to find vulnerabilities during the early stages of software development cycle, as security aspects are often not known adequately. To counter these security implications, firms usually provide patches such that these security flaws are not exploited. It is a daunting task for a security manager to prioritize patches for vulnerabilities that are likely to be exploitable. This paper fills this gap by applying different machine learning techniques to classify the vulnerabilities based on previous exploit-history. Our work indicates that various vulnerability characteristics such as severity, type of vulnerabilities, different software configurations, and vulnerability scoring parameters are important features to be considered in judging an exploit. Using such methods, it is possible to predict exploit-prone vulnerabilities with an accuracy >85%. Finally, with this experiment, we conclude that supervised machine learning approach can be a useful technique in predicting exploit-prone vulnerabilities.     

Structure–Activity Relationships of Benzenesulfonamide‐Based Inhibitors towards Carbonic Anhydrase Isoform Specificity

Carbonic anhydrases (CAs) are implicated in a wide range of diseases, including the upregulation of isoforms CA IX and XII in many aggressive cancers. However, effective inhibition of disease‐implicated CAs should minimally affect the ubiquitously expressed isoforms, including CA I and II, to improve directed distribution of the inhibitors to the cancer‐associated isoforms and reduce side effects. Four benzenesulfonamide‐based inhibitors were synthesized by using the tail approach and displayed nanomolar affinities for several CA isoforms. The crystal structures of the inhibitors bound to a CA IX mimic and CA II are presented. Further in silico modeling was performed with the inhibitors docked into CA I and XII to identify residues that contributed to or hindered their binding interactions. These structural studies demonstrated that active‐site residues lining the hydrophobic pocket, especially positions 92 and 131, dictate the positional binding and affinity of inhibitors, whereas the tail groups modulate CA isoform specificity. Geometry optimizations were performed on each ligand in the crystal structures and showed that the energetic penalties of the inhibitor conformations were negligible compared to the gains from active‐site interactions. These studies further our understanding of obtaining isoform specificity when designing small molecule CA inhibitors.     

Nanoindentation studies on amorphous, nanoquasicrystalline and nanocrystalline Zr8oPt2o and Zr75Pd25 alloys

Nanoindentation studies on rapidly solidified Zr80Pt20 and Zr75Pd25 binary alloys with nanocrystalline, nanoquasicrystalline, and amorphous microstructures are reported. The results indicate that the hardness and elastic modulus are the highest for a mixture of amorphous and nanoquasicrystalline state among the various microstructures studied. Nanoquasicrystalline phase has high hardness and elastic modulus in comparison to amorphous and nanocrystalline phases. The hardness to modulus ratio is close to 0.1 in both the alloys, irrespective of the phase/phase mixture studied indicating that the bonding in these alloys is of covalent nature. In Zr80Pt20, all the phases/phase mixtures have higher hardness and modulus in comparison to similar microstructures in Zr75Pd25 due to higher bond energies caused by more negative heat of mixing in the former case.     

Influence of nitrogen in the shielding gas on corrosion resistance of duplex stainless steel welds

The influence of nitrogen in shielding gas on the corrosion resistance of welds of a duplex stainless steel (grade U-50), obtained by gas tungsten arc (GTA) with filler wire, autogenous GTA (bead-on-plate), electron beam welding (EBW), and microplasma techniques, has been evaluated in chloride solutions at 30 °C. Pitting attack has been observed in GTA, electron beam welding, and microplasma welds when welding has been carried out using pure argon as the shielding gas. Gas tungsten arc welding with 5 to 10% nitrogen and 90 to 95% argon, as the shielding gas, has been found to result in an improved pitting corrosion resistance of the weldments of this steel. However, the resistance to pitting of autogenous welds (bead-on-plate) obtained in pure argon as the shielding gas has been observed to remain unaffected. Microscopic examination, electron probe microanalysis (EPMA), and x-ray diffraction studies have revealed that the presence of nitrogen in the shielding gas in the GTA welds not only modifies the microstructure and the austenite to ferrite ratio but also results in a nearly uniform distribution of the various alloying elements, for example, chromium, nickel, and molybdenum among the constitutent phases, which are responsible for improved resistance to pitting corrosion.     

Near‐infrared transmittance spectroscopy: a potential tool for non‐destructive determination of oil content in groundnuts

The oil content of 64 samples of groundnut kernels, representing 47 genotypes, was determined by the conventional Soxhlet extraction procedure (Oil^SOX). The values of Oil^SOX ranged from 403 to 536 g kg⁻¹. The optical densities (ODs) of these samples were determined at 12 wavelengths (918, 928, 940, 950, 968, 975, 985, 998, 1010, 1023, 1037 and 1045 nm) in the near‐infrared (NIR) region using a food composition analyser (essentially a filter‐based NIR spectrophotometer). The instrument also recorded the temperatures of the sample (Temp^S) and the air (Temp^A) surrounding it. A sample holder (75 mm × 150 mm; optical path length 25 mm) was used for optical density measurement. The data obtained were subjected to multiple linear regression analysis using the ODs at 12 wavelengths, Temp^S and Temp^A as the independent (predictor) variables, and Oil^SOX as the dependent variable. The multiple linear regression equation comprising 14 predictors showed a significant relationship between predicted values of oil content (Oil^NIR) and Oil^SOX. The standard error of calibration and the coefficient of determination for calibration (R) were 3.54 and 0.821 respectively, while the standard error of prediction and the coefficient of determination for prediction were 5.82 and 0.865 respectively. The ratio of standard error of calibration and standard error of prediction was 0.608. The differences between Oil^SOX and Oil^NIR were less than ± 20 g kg⁻¹ for samples having oil contents in the range from 480 to 510 g kg⁻¹. However, for samples having Oil^SOX lower than 480 g kg⁻¹ or higher than 510 g kg⁻¹, differences greater than ± 20 g kg⁻¹ were observed. There exists scope for further refining the regression equation by using a larger number of samples for generating optical data. The results demonstrated the potential of NIR transmittance spectroscopy for determining the oil content of groundnuts in a non‐destructive manner. © 2000 Society of Chemical Industry     

Matrix-induced variation in kinetics and control of molecular weight of methacrylic acid polymers during graft copolymerization with starch

Polymerization of synthetic monomers is known to be influenced by the solvent, initiator system, dilution, temperature, etc. Substrates like starch granules, when used for graft copolymerization, can be expected to provide a drastically different environment for the monomers (as compared to the bulk of the solvent medium), and therefore we predicted this to influence the kinetics of polymerization and stereoregularity of the synthetic polymer. This was investigated with respect to polymerization of methacrylic acid with starch. The rate of methacrylic acid polymerization was found to be significantly higher in grafting with starch as compared to homopolymerization in the absence of starch. Control of molecular weight of the grafted chains was achieved by use of chain transfer agents, and the chain transfer constants for graft copolymerization were determined for two chain transfer agents. The polydispersity of the grafted chains was also found to be dependent on the chain transfer agents. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 397–403, 1997