Effect of Secondary Structure and Side Chain Length of Hydrophobic Amino Acid Residues on the Antimicrobial Activity and Toxicity of 14-Residue-Long de novo AMPs

Herein we report the efficacy and toxicity of three de novo designed cationic antimicrobial peptides (AMPs) LL-14, VV-14 and ββ-14, where side chains of the hydrophobic amino acids were reduced gradually. The AMPs showed broad-spectrum antimicrobial activity against three pathogens from the ESKAPE group and two fungal strains. This study showed that side chains which are either too long or too short increase toxicity and lower antimicrobial activity, respectively. VV-14 was found to be non-cytotoxic and highly potent under physiological salt concentrations against several pathogens, especially Salmonella typhi TY2. These AMPs acted via membrane deformation, depolarization, and lysis. The activity of the AMPs is related to their ability to take on amphipathic helical conformations in the presence of microbial membrane mimics. Among AMPs with the same charge, hydrophobic interactions between the side chains of the residues with cell membrane lipids determine their antimicrobial potency and cytotoxicity. Strikingly, an optimum hydrophobic interaction is the crux of generating highly potent non-cytotoxic AMPs.     

Robust Antiskyrmion Phase in Bulk Tetragonal Mn–Pt(Pd)–Sn Heusler System Probed by Magnetic Entropy Change and AC‐Susceptibility Measurements

Magnetic skyrmions, topologically protected chiral spin textures having potential applications in data storage, are stabilized in certain magnetic materials with broken inversion symmetry. The existence of magnetic antiskyrmions has been recently demonstrated in thin plates of a tetragonal Heusler material with D_2d crystal symmetry. Here, the robust nature of the antiskyrmion phase in bulk tetragonal Mn–Pt(Pd)–Sn compounds by utilizing magnetic entropy change and AC‐susceptibility measurements is shown. It is found that the formation of the antiskyrmion phase is accompanied by a positive magnetic entropy change, which is supported by the concomitant observation of an anomaly in AC‐susceptibility measurements. Supporting these findings, no anomalies are found in AC‐susceptibility and magnetic entropy change measurements for a Mn–Pt(Pd)–Sn compound that is stabilized in the cubic phase by slight changes in chemical composition, thereby showing the robustness of the antiskyrmion phase to the D_2d crystal structure.     

A novel infinite 1D covalent chain of end-to-end thiocyanato bridged heptacoordinated cadmium(II)Schiff base: π…π interaction and weak C–H…S hydrogen bonded supramolecule

A new Schiff base, N,N′-(bis(pyridin-2-yl)formylidene)ethane-1,2-diamine (bpfd) is prepared and used to synthesize a novel end-to-end thiocyanato bridged infinite 1D polymeric heptacoordinated cadmium(II) chain [Cd(bpfd)(μ_1,3-NCS)(NCS)]_n (1) which forms a 3D supramolecule through weak C–H…S hydrogen bonding and π…π interaction.     

Early cellular and humoral response after vascular prosthesis implantation in the arterial system]

The aim of the study was to determine the level of leukocytes activation after the implantation of vascular graft. As an experimental model we used 20 dogs. The aorto-iliac unilateral graft (dacron 6 mm) was implanted to all animals. The adhesion and migration of the leukocytes was estimated postoperatively by scintigraphy using Tc99 labeled leukocytes. The increased migration and adhesion was found in both proximal and distal anastomoses till the 30th postoperative day and it was more intensive in the distal anastomosis.     

Nucleobase Modified Adefovir (PMEA) Analogues as Potent and Selective Inhibitors of Adenylate Cyclases from Bordetella pertussis and Bacillus anthracis

A series of 13 acyclic nucleoside phosphonates (ANPs) as bisamidate prodrugs was prepared. Five compounds were found to be non‐cytotoxic and selective inhibitors of Bordetella pertussis adenylate cyclase toxin (ACT) in J774A.1 macrophage cell‐based assays. The 8‐aza‐7‐deazapurine derivative of adefovir (PMEA) was found to be the most potent ACT inhibitor in the series (IC₅₀=16 nm ) with substantial selectivity over mammalian adenylate cyclases (mACs). AC inhibitory properties of the most potent analogues were confirmed by direct evaluation of the corresponding phosphonodiphosphates in cell‐free assays and were found to be potent inhibitors of both ACT and edema factor (EF) from Bacillus anthracis (IC₅₀ values ranging from 0.5 to 21 nm ). Moreover, 7‐halo‐7‐deazapurine analogues of PMEA were discovered to be potent and selective mammalian AC1 inhibitors (no inhibition of AC2 and AC5) with IC₅₀ values ranging from 4.1 to 5.6 μm in HEK293 cell‐based assays.     

Line spectral frequency-based features and extreme learning machine for voice activity detection from audio signal

Voice activity detection (VAD) refers to the task of identifying vocal segments from an audio clip. It helps in reducing the computational overhead as well elevate the recognition performance of speech-based systems by helping to discard the non vocal portions from an input signal. In this paper, a VAD technique is presented that uses line spectral frequency-based statistical features namely LSF-S coupled with extreme learning-based classification. The experiments were performed on a database of more than 350 h consisting of data from multifarious sources. We have obtained an encouraging overall accuracy of 99.43%.     

Modelling and optimization of syngas production by methane dry reforming over samarium oxide supported cobalt catalyst: response surface methodology and artificial neural networks approach

The reforming of methane by carbon dioxide for the production of syngas is a potential technological route for the mitigation of greenhouse gases. However, the process is highly endothermic and often accompanied by catalyst deactivation from sintering and carbon deposition. Besides, the applications of dissimilar catalytic systems in methane dry reforming have made it difficult to obtain generalized optimum conditions for the desired products. Hence, optimization studies of any catalytic system often resulted in a unique optimum condition. The present study aimed to investigate optimum conditions of variables such as methane (CH₄) partial pressure, carbon dioxide (CO₂) partial pressure and reaction temperature that will maximize syngas yields from methane dry reforming over samarium oxide supported cobalt (Co/Sm₂O₃) catalyst. The Co/Sm₂O₃ catalyst was synthesized using wet-impregnation method and characterized by thermogravimetric analysis), field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray powder diffraction and nitrogen (N₂) physisorption. Syngas production by methane dry reforming over the synthesized Co/Sm₂O₃ catalyst was investigated in a stainless steel fixed-bed reactor. The process variables (CH₄ partial pressure, CO₂ partial pressure and reaction temperature) for the syngas production were optimized using response surface methodology (RSM). The RSM and artificial neural networks (ANNs) were used to predict the syngas production from the experimental data. The comparative analysis between the two models showed that the ANN model has better prediction of the syngas yields compared to the RSM model as evident from the good agreement between the observed and the predicted values. At maximum desirability value of 0.97, optimum CH₄ and CO₂ partial pressures of 47.9 and 48.9 kPa were obtained at reaction temperature of 735 °C resulting in syngas yield of ~79.4 and 79.0% for hydrogen (H₂) and carbon monoxide (CO), respectively.     

Small signal behavioral modeling technique of GaN high electron mobility transistor using artificial neural network: An accurate,fast, and reliable approach

This article reports a comparative study of two artificial neural network structures and associated variants used to describe and predict the behavior of 2 × 200 μm² GaN high electron mobility transistors (HEMTs), utilizing radiofrequency characterization. Two architectures namely multilayer perceptron and cascade feedforward, have been investigated in this work to develop the behavioral model. A study is conducted utilizing the two architectures, all trained using Levenberg‐Marquardt, in terms of accuracy, convergence rate, and generalization capability to develop the behavioral model of GaN HEMT. However, to ensure the robustness of the model, accuracy, convergence rate, time elapsed, and generalization capability of the proposed model is also tested under couple of training algorithms, activation functions, number of hidden layers and neuron embedded inside it, methods for initialization of weights and bias and certain other vital parameters playing vital role in influencing the model accuracy and effectiveness. An excellent agreement found between measured S‐parameters and the proposed model proves the effectiveness of the proposed approach and excellent prediction ability for a sweeping multibias set and broad frequency range of 1 to 18 GHz. Moreover, a very good generalization capability is also recorded under variation of crucial parameters of GaN HEMT‐based neural model.     

Evaluation of similarity measures for video retrieval

Multimedia Tools and Applications - Similarity measures are very crucial especially in the field of information retrieval. Thus, various distance/similarity measures were proposed throughout the...