Approximate Bayes estimators applied to the Bilal model

This paper develops approximate Bayes estimators of the parameter of the Bilal failure model by using the method of Tierney and Kadane [Accurate approximations for posterior moments and marginal densities, J. Amer. Statist. Assoc. 81 (1986) 82–86.] based on Type-2 censored sample and four different loss functions. Existence and uniqueness theorem for the maximum likelihood estimate are established. Based on Monte Carlo simulation study, comparisons are made between those estimators and their corresponding Bayes estimators obtained by using Gibb’s sampling approach.     

Response and stability analysis of piecewise-linear oscillators under multi-forcing frequencies

Steady-state solutions of a piecewise-linear oscillator under multi-forcing frequencies are obtained using the fixed point algorithm (FPA). Stability analysis is also performed using the same technique. For the periodic solutions of a piecewise-linear oscillator with single forcing frequency, the harmonic balance method (HBM) is also used along with the FPA. Although both FPA and HBM generate accurate solutions, it is observed that the HBM failed to converge to solutions in the superharmonic range of the forcing frequency.The fixed point algorithm was also applied to the oscillator under multifrequency excitation. The algorithm proved to be very effective in obtaining torus solutions and in locating corresponding bifurcation thresholds. A piecewise-linear oscillator model of an offshore articulated loading platform (ALP) subjected to two incommensurate wave frequencies is found to exhibit chaotic behavior. A second order Poincaré mapping technique reveals the hidden fractal-like nature of the resulting chaotic response. A parametric study is performed for the response of the ALP.     

A Global Review on Short Peptides: Frontiers and Perspectives

Peptides are fragments of proteins that carry out biological functions. They act as signaling entities via all domains of life and interfere with protein-protein interactions, which are indispensable in bio-processes. Short peptides include fundamental molecular information for a prelude to the symphony of life. They have aroused considerable interest due to their unique features and great promise in innovative bio-therapies. This work focusing on the current state-of-the-art short peptide-based therapeutical developments is the first global review written by researchers from all continents, as a celebration of 100 years of peptide therapeutics since the commencement of insulin therapy in the 1920s. Peptide “drugs” initially played only the role of hormone analogs to balance disorders. Nowadays, they achieve numerous biomedical tasks, can cross membranes, or reach intracellular targets. The role of peptides in bio-processes can hardly be mimicked by other chemical substances. The article is divided into independent sections, which are related to either the progress in short peptide-based theranostics or the problems posing challenge to bio-medicine. In particular, the SWOT analysis of short peptides, their relevance in therapies of diverse diseases, improvements in (bio)synthesis platforms, advanced nano-supramolecular technologies, aptamers, altered peptide ligands and in silico methodologies to overcome peptide limitations, modern smart bio-functional materials, vaccines, and drug/gene-targeted delivery systems are discussed.     

Chemical Profile of Launaea nudicaulis Ethanolic Extract and Its Antidiabetic Effect in Streptozotocin-Induced Rats

Launaea nudicaulis is used in folk medicine worldwide to treat several diseases. The present study aimed to assess the antidiabetic activity of L. nudicaulis ethanolic extract and its effect on diabetic complications in streptozotocin-induced hyperglycemic rats. The extract was orally administrated at 250 and 500 mg/kg/day for 5-weeks and compared to glibenclamide as a reference drug at a dose of 5 mg/kg/day. Administration of the extract exhibited a potential hypoglycemic effect manifested by a significant depletion of serum blood glucose concurrent with a significant elevation in serum insulin secretion. After 5-weeks, extract at 250 and 500 mg/kg/day decreased blood glucose levels by about 53.8 and 68.1%, respectively, compared to the initial values (p ≤ 0.05). The extract at the two dosages prevented weight loss of rats from the 2nd week till the end of the experiment, compared to diabetic control rats. The extract further exhibited marked improvement in diabetic complications including liver, kidney and testis performance, oxidative stress, and relative weight of vital organs, with respect to diabetic control. Histopathological examinations confirmed the previous biochemical analysis, where the extract showed a protective effect on the pancreas, liver, kidney, and testis that degenerated in diabetic control rats. To characterize extract composition, UPLC-ESI–qTOF-MS identified 85 chromatographic peaks belonging to flavonoids, phenolics, acyl glycerols, nitrogenous compounds, and fatty acids, with four novel phenolics reported. The potential anti-diabetic effect warrants its inclusion in further studies and or isolation of the main bioactive agent(s).     

Corrosion inhibition by benzotriazole derivatives and sodium dodecyl sulphate as corrosion inhibitors for copper in ground water at different temperatures

1‐(2‐Pyrrole carbonyl) benzotriazole (PBTA) and 1‐(2‐thienyl carbonyl)‐benzotriazole (TBTA) were synthesized. Different concentrations of PBTA, TBTA, sodium dodecyl sulphate (SDS), and molybdate (Mo) were evaluated as corrosion inhibitors for copper in ground water medium at different temperatures. The obtained results were compared with the effect of benzotriazole (BTA) on the inhibition of copper corrosion at the same condition. The study was performed using potentiodynamic polarization, electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy investigations. A good inhibition is ensured at elevated temperatures. All measurements indicated that PBTA, TBTA, and BTA act as good corrosion inhibitors and their inhibition efficiency (IE%) increased with combining them with optimum concentration of SDS and Mo. Furthermore, the best performance was recorded for the compound PBTA + SDS + Mo, which was found to offer increased IE% in a synergistic manner, thereby acting as a good corrosion inhibitor for copper in ground water medium. Copyright © 2015 John Wiley & Sons, Ltd.     

Hierarchical C-N doped NiO with dual-head echinop flowers for ultrasensitive monitoring of epinephrine in human blood serum

Microchimica Acta - The authors describe nanoelectrodes based on the use of hierarchical carbon-nitrogen nanospheres and dual-head nickel oxide echinop flowers (CN@HDN) placed on indium tin oxide...     

Cytotoxic labdane diterpenes and bisflavonoid atropisomers from leaves of Araucaria bidwillii

Chemical investigation of a methanolic extract of leaves from Araucaria bidwillii (Araucariaceae) from Egypt afforded four new labdane diterpenoidal metabolites (1–4) together with one known diterpene, 7-oxocallitrisic acid (5), two triterpenoidal metabolites, 2-O-acetyl-11-keto-boswellic acid (6) and β-sitosterol-3-O-glucopyranoside (7), phloretic acid (8), and two methylated bisflavonoids, agathisflavone-4′,7,7″-trimethyl ether (9) and cupressuflavone-4′,7,7″-trimethyl ether (10). The new metabolites 1–4 were unambiguously identified by applying extensive 1D and 2D NMR spectroscopic studies as well as HRESIMS. The relative and absolute configurations of 1–4 were determined using ROESY and the modified Mosher's method, respectively. All isolated compounds were assessed for their antimicrobial, antitubercular and cytotoxic activities. Among the tested compounds, the new labdane diterpenes 1–4 revealed significant cytotoxic activity against mouse lymphoma L5178Y cell line with IC₅₀ values ranging from 1.4 to 12.9 μM, respectively.     

Micro‐Raman spectroscopic investigations of extremely scarce Pb–As sulfosalt minerals: baumhauerite,dufrénoysite,gratonite, sartorite,and seligmannite

The overmuch rare lead arsenic sulfosalts, baumhauerite (Pb₃As₄S₉), dufrénoysite (Pb₂As₂S₅), gratonite (Pb₉As₄S₁₅), sartorite (PbAs₂S₄), and seligmannite (PbCuAsS₃), were investigated by Raman spectroscopy. Raman spectra of the investigated minerals arise from the stretching and bending modes of the isolated and interconnected AsS₃ pyramidal groups. The As–S stretching vibrations of the studied minerals occur between 390 and 340 cm⁻¹, whereas those of S–As–S bending modes between 335 and 220 cm⁻¹. The shorter bond distances of the As–S readily elucidate the blue shift from seligmannite to gratonite, sartorite, dufrénoysite, and baumhauerite and the increase in full width at half maximum in similar modes. Copyright © 2016 John Wiley & Sons, Ltd.     

Nanomembrane Canister Architectures for the Visualization and Filtration of Oxyanion Toxins with One‐Step Processing

Nanomembrane canister‐like architectures were fabricated by using hexagonal mesocylinder‐shaped aluminosilica nanotubes (MNTs)–porous anodic alumina (PAA) hybrid nanochannels. The engineering pattern of the MNTs inside a 60 μm‐long membrane channel enabled the creation of unique canister‐like channel necks and cavities. The open‐tubular canister architecture design provides controllable, reproducible, and one‐step processing patterns of visual detection and rejection/permeation of oxyanion toxins such as selenite (SeO₃^2?) in aquatic environments (i.e., in ground and river water sources) in the Ibaraki Prefecture of Japan. The decoration of organic ligand moieties such as omega chrome black blue (OCG) into inorganic Al₂O₃@tubular SiO₂/Al₂O₃ canister membrane channel cavities led to the fabrication of an optical nanomembrane sensor (ONS). The OCG ligand was not leached from the canister as observed in washing, sensing, and recovery assays of selenite anions in solution, which enabled its multiple reuse. The ONS makes a variety of alternate processing analyses of selective quantification, visual detection, rejection/permeation, and recovery of toxic selenite quick and simple without using complex instrumentation. Under optimal conditions, the ONS canister exhibited a high selectivity toward selenite anions relative to other ions and a low‐level detection limit of 0.0093 μm . Real analytical data showed that approximately 96 % of SeO₃^2? anions can be recovered from aquatic and wastewater samples. The ONS canister holds potential for field recovery applications of toxic selenite anions from water.     

Dispacamide E and other bioactive bromopyrrole alkaloids from two Indonesian marine sponges of the genus Stylissa

Chemical investigation of methanolic extracts of the two Indonesian marine sponges Stylissa massa and Stylissa flabelliformis yielded 25 bromopyrrole alkaloids including 2 new metabolites. The structures of all isolated compounds were unambiguously elucidated based on extensive 1D and 2D NMR, LR-MS and HR-MS analyses. All isolated compounds were assayed for their antiproliferative and protein kinase inhibitory activities. Several of the tested compounds revealed selective activity(ies) which suggested preliminary SARs of the isolated bromopyrrole alkaloids.