Discovery and Biosynthesis of Ureidopeptide Natural Products Macrocyclized via Indole N-acylation in Marine Microbulbifer spp. Bacteria

Commensal bacteria associated with marine invertebrates are underappreciated sources of chemically novel natural products. Using mass spectrometry, we had previously detected the presence of peptidic natural products in obligate marine bacteria of the genus Microbulbifer cultured from marine sponges. In this report, the isolation and structural characterization of a panel of ureidohexapeptide natural products, termed the bulbiferamides, from Microbulbifer strains is reported wherein the tryptophan side chain indole participates in a macrocyclizing peptide bond formation. Genome sequencing identifies biosynthetic gene clusters encoding production of the bulbiferamides and implicates the involvement of a thioesterase in the indolic macrocycle formation. The structural diversity and widespread presence of bulbiferamides in commensal microbiomes of marine invertebrates point toward a possible ecological role for these natural products.     

Effect of cloisite 30B clay and sisal fiber on dynamic mechanical and fracture behavior of unsaturated polyester toughened epoxy network

This study examined the dynamic mechanical properties of sisal fiber reinforced unsaturated polyester (UP) toughened epoxy nanocomposites. The chemical structures changes in Epoxy, UP and UP toughened epoxy (Epoxy/UP) systems were characterized by Proton Nuclear magnetic resonance (¹HNMR) spectroscopy. The morphological alterations of the nanocomposites were analyzed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The untreated, chemically treated fibers, nanoclays, and the fiber reinforced Epoxy/UP nanocomposites were confirmed by FTIR spectrometer. The obtained mechanical results showed that alkali‐silane treated fibers improve the tensile strength (96%) and flexural strength (60%) of the Epoxy/UP nanocomposite than that of Epoxy/UP blend due to the strong interfacial bonding between the sisal fiber and matrix. The fracture toughness (K_IC) and fracture energy (G_IC) of treated sisal fiber reinforced DGEBA/UP/C30B nanocomposites found to be higher than that of untreated sisal fiber nanocomposites. The dynamic mechanical analysis (DMA) reveals that the fiber reinforced Epoxy/UP nanocomposites contains 30 wt% treated fiber and 1 wt% nanoclays, exhibits the highest storage modulus and better glass transition temperature (T_g) among the other kind of systems. The surface morphology of the fibers, fractured surface of the resins and composites were confirmed by scanning electron microscope (SEM). POLYM. COMPOS., 37:2832–2846, 2016. © 2015 Society of Plastics Engineers     

Financial sustainability of rural water supply: An analysis of cost recovery,revenue collection,and efficiency

Maintaining a financial sustainable pipe water supply (PWS) is one of the serious challenges in sustainable provision of water supply in rural areas. Poor revenue collection and willingness to pay for the service is adding severity to the problem. This study analyses the factors affecting revenue collection in rural water utilities and measures its efficiency in maximizing revenue and average hour of water supply per day. The findings convey that cost recovery is a failure in rural water supply even they are not able to generate revenue. Inactive community participation, the notion of free water supply, unaccountable payment is main reason for poor revenue collection. Therefore, active community participations, educating the household on water supply, adoption of accountable payment mode will be a step towards revenue generation. To attain efficiency, the utilities can expand their output revenue and hours of water supply by 22% without altering their input. This study is an empirical contribution in the field of sustainable provision of water supplies, which address the problem of poor revenue generation in rural water supply and find out the reason for it.     

Effect of UV Stress on the Structure and Function of Pro-apoptotic Bid and Anti-apoptotic Bcl-xl proteins

Ultraviolet C (UV-C) radiation induces apoptosis in mammalian cells via the mitochondrion-mediated pathway. The Bcl-2 family of proteins are the regulators of the mitochondrial pathway of apoptosis and appears responsive to UV-C radiation. It is unknown how the structure and, effectively, the function of these proteins are directly impacted by UV-C exposure. Here, we present the effect of UV-C irradiation on the structure and function of pro-apoptotic Bid-FL and anti-apoptotic Bcl-xlΔC proteins. Using a variety of biophysical tools, we show that, following UV-C irradiation, the structures of Bcl-xlΔC and Bid-FL are irreversibly altered. Bcl-xLΔC is found to be more sensitive to UV stress than Bid-FL Interestingly, UV-C exposure shows dramatic chemical shift perturbations in consequence of dramatic structural perturbations (α-helix to β-sheet) in the BH3- binding region, a crucial segment of Bcl-xlΔC. Furter it has been shown that UV-exposed Bcl-xlΔC has reduced efficacy of its interactions with pro-apoptotic tBid.     

Alumina Nanoparticle Interfacial Buffer Layer for Low-Bandgap Lead-Tin Perovskite Solar Cells

Mixed lead-tin (Pb:Sn) halide perovskites are promising absorbers with narrow-bandgaps (1.25–1.4 eV) suitable for high-efficiency all-perovskite tandem solar cells. However, solution processing of optimally thick Pb:Sn perovskite films is notoriously difficult in comparison with their neat-Pb counterparts. This is partly due to the rapid crystallization of Sn-based perovskites, resulting in films that have a high degree of roughness. Rougher films are harder to coat conformally with subsequent layers using solution-based processing techniques leading to contact between the absorber and the top metal electrode in completed devices, resulting in a loss of V_OC, fill factor, efficiency, and stability. Herein, this study employs a non-continuous layer of alumina nanoparticles distributed on the surface of rough Pb:Sn perovskite films. Using this approach, the conformality of the subsequent electron-transport layer, which is only tens of nanometres in thickness is improved. The overall maximum-power-point-tracked efficiency improves by 65% and the steady-state V_OC improves by 28%. Application of the alumina nanoparticles as an interfacial buffer layer also results in highly reproducible Pb:Sn solar cell devices while simultaneously improving device stability at 65 °C under full spectrum simulated solar irradiance. Aged devices show a six-fold improvement in stability over pristine Pb:Sn devices, increasing their lifetime to 120 h.     

Selective Binding of Small Molecules to Vibrio cholerae DsbA Offers a Starting Point for the Design of Novel Antibacterials

DsbA enzymes catalyze oxidative folding of proteins that are secreted into the periplasm of Gram-negative bacteria, and they are indispensable for the virulence of human pathogens such as Vibrio cholerae and Escherichia coli. Therefore, targeting DsbA represents an attractive approach to control bacterial virulence. X-ray crystal structures reveal that DsbA enzymes share a similar fold, however, the hydrophobic groove adjacent to the active site, which is implicated in substrate binding, is shorter and flatter in the structure of V. cholerae DsbA (VcDsbA) compared to E. coli DsbA (EcDsbA). The flat and largely featureless nature of this hydrophobic groove is challenging for the development of small molecule inhibitors. Using fragment-based screening approaches, we have identified a novel small molecule, based on the benzimidazole scaffold, that binds to the hydrophobic groove of oxidized VcDsbA with a K_D of 446±10 μM. The same benzimidazole compound has ∼8-fold selectivity for VcDsbA over EcDsbA and binds to oxidized EcDsbA, with K_D>3.5 mM. We generated a model of the benzimidazole complex with VcDsbA using NMR data but were unable to determine the structure of the benzimidazole bound EcDsbA using either NMR or X-ray crystallography. Therefore, a structural basis for the observed selectivity is unclear. To better understand ligand binding to these two enzymes we crystallized each of them in complex with a known ligand, the bile salt sodium taurocholate. The crystal structures show that taurocholate adopts different binding poses in complex with VcDsbA and EcDsbA, and reveal the protein-ligand interactions that stabilize the different modes of binding. This work highlights the capacity of fragment-based drug discovery to identify inhibitors of challenging protein targets. In addition, it provides a starting point for development of more potent and specific VcDsbA inhibitors that act through a novel anti-virulence mechanism.     

Automated Artificial Intelligence Empowered White Blood Cells ClassificationModel

White blood cells (WBC) or leukocytes are a vital component of the blood which forms the immune system, which is accountable to fight foreign elements. The WBC images can be exposed to different data analysis approaches which categorize different kinds of WBC. Conventionally, laboratory tests are carried out to determine the kind of WBC which is erroneous and time consuming. Recently, deep learning (DL) models can be employed for automated investigation of WBC images in short duration. Therefore, this paper introduces an Aquila Optimizer with Transfer Learning based Automated White Blood Cells Classification (AOTL-WBCC) technique. The presented AOTL-WBCC model executes data normalization and data augmentation process (rotation and zooming) at the initial stage. In addition, the residual network (ResNet) approach was used for feature extraction in which the initial hyperparameter values of the ResNet model are tuned by the use of AO algorithm. Finally, Bayesian neural network (BNN) classification technique has been implied for the identification of WBC images into distinct classes. The experimental validation of the AOTL-WBCC methodology is performed with the help of Kaggle dataset. The experimental results found that the AOTL-WBCC model has outperformed other techniques which are based on image processing and manual feature engineering approaches under different dimensions.     

Twisted Crystalline Organic Semiconductor Photodetectors

Optoelectronic properties of anisotropic crystals vary with direction requiring that the orientation of molecular organic semiconductor crystals is controlled in optoelectronic device active layers to achieve optimal performance. Here, a generalizable strategy to introduce periodic variations in the out-of-plane orientations of 5,11-bis(triisopropylsilylethynyl)anthradithiophene (TIPS ADT) crystals is presented. TIPS ADT crystallized from the melt in the presence of 16 wt.% polyethylene (PE) forms banded spherulites of crystalline fibrils that twist in concert about the radial growth direction. These spherulites exhibit band-dependent light absorption, photoluminescence, and Raman scattering depending on the local orientation of crystals. Mueller matrix imaging reveals strong circular extinction (CE), with TIPS ADT banded spherulites exhibiting domains of positive or negative CE signal depending on the crystal twisting sense. Furthermore, orientation-dependent enhancement in charge injection and extraction in films of twisted TIPS ADT crystals compared to films of straight crystals is visualized in local conductive atomic force microscopy maps. This enhancement leads to 3.3- and 6.2-times larger photocurrents and external quantum efficiencies, respectively, in photodetectors comprising twisted crystals than those comprising straight crystals.     

Segmented Drain Engineered Tunnel Field Effect Transistor for Suppression of Ambipolarity

Silicon - In this paper, a new Si0.6Ge0.4/Si heterostructure tunneling field-effect transistor with segmented drain (SiGe/Si SD TFET) is proposed and simulated by Silvaco ATLAS simulator. The drain...