Optimization of process conditions in casting aluminum matrix composites via interconnection of artificial neurons and progressive solutions

A genetic algorithm is a machine learning technique that was inspired by the analogy of biological evolution which generates solutions by repeatedly mutating and recombining parts of the best currently known solutions. In order to model and optimize the properties of A356 matrix composites, a finite element method (FEM) with artificial neural network based genetic algorithm (ANN-GA) model was developed. The tribological and mechanical properties of the aluminum matrix composite were also experimentally investigated. The results verified the accuracy of the proposed model to find the optimal process conditions in aluminum matrix composite materials.     

Synthesis and characterization of novel pH-, ionic strength and temperature- sensitive hydrogel for insulin delivery

A series of novel silane crosslinked hydrogel was prepared from kappa carrageenan (KC), acrylic acid (AA) using vinyltriethoxysilane (VTESi). Potassium persulphate initiated the grafting and copolymerization reactions between reactants. In addition, the condensation of the hydroxyl groups of KC and VTESi resulted into crosslinking. Novelty of this work is the use of VTESi as crosslinker for such a composition of hydrogel. The structure of prepared hydrogels was characterized by Fourier transform infrared spectroscopy. The analysis of spectra confirmed the presence of feed components in the prepared hydrogels. Thermogravimetric analysis showed an increase in the stability of the hydrogels either having high AA contents or crosslinker amount. The effect of feed components, pH (buffer, non-buffer), electrolytic media and temperature on the swelling behaviour of the hydrogels is reported here.Most promising results with high swelling ratio were observed in hydrogel having low monomeric ratio (KC:AA = 1:7). pH response of this hydrogel in acidic and neutral pH makes it suitable for drug delivery application. Insulin, a protein based drug was selected as a model drug. It requires its delivery in small intestine for proper action; therefore its release behaviour was studied in-vitro in simulated stomach and intestinal fluids. The release profile of insulin showed negligible release in simulated gastric fluid (SGF) and sustained release in simulated intestinal fluid (SIF). The obtained results are in good agreement with the swelling response of this hydrogel. The weak structure of this hydrogel makes it preferable for drug delivery, as it is able to get crumbled after releasing the drug for 6 h at neutral pH.     

Cross-Buoyancy Mixed Convection Around a Confined Triangular Bluff Body

Two-dimensional numerical simulations are carried out to understand the effects of cross-buoyancy on the confined flow and heat transfer characteristics over an equilateral triangular bluff body at low and intermediate Reynolds numbers (Re). For a fixed Richardson number (Ri), an average cylinder Nusselt number increases with increasing Re. However, the average Nusselt number shows a soft response toward increasing Ri. The critical Re for the onset of periodic unsteady flow increases with increasing cross-buoyancy (Ri). A simple heat transfer correlation is also obtained to relate the values of average cylinder Nusselt number, Re, and Ri.     

Evaluation of Heat Treatment Effect on the Tensile Strength of Mild Steel Welded Joints Using Ultrasonic Testing

Russian Journal of Nondestructive Testing - The tensile strength of welded joints subjected to thermal stresses degrades with age. Tensile strength is generally assessed using tensile test, which...     

Highly-Directional,Highly-Efficient Solution-Processed Light-Emitting Diodes of All-Face-Down Oriented Colloidal Quantum Well Self-Assembly

Semiconductor colloidal quantum wells (CQWs) provide anisotropic emission behavior originating from their anisotropic optical transition dipole moments (TDMs). Here, solution-processed colloidal quantum well light-emitting diodes (CQW-LEDs) of a single all-face-down oriented self-assembled monolayer (SAM) film of CQWs that collectively enable a supreme level of IP TDMs at 92% in the ensemble emission are shown. This significantly enhances the outcoupling efficiency from 22% (of standard randomly-oriented emitters) to 34% (of face-down oriented emitters) in the LED. As a result, the external quantum efficiency reaches a record high level of 18.1% for the solution-processed type of CQW-LEDs, putting their efficiency performance on par with the hybrid organic-inorganic evaporation-based CQW-LEDs and all other best solution-processed LEDs. This SAM-CQW-LED architecture allows for a high maximum brightness of 19,800 cd m⁻² with a long operational lifetime of 247 h at 100 cd m⁻² as well as a stable saturated deep-red emission (651 nm) with a low turn-on voltage of 1.7 eV at a current density of 1 mA cm⁻² and a high J₉₀ of 99.58 mA cm⁻². These findings indicate the effectiveness of oriented self-assembly of CQWs as an electrically-driven emissive layer in improving outcoupling and external quantum efficiencies in the CQW-LEDs.     

Half-Metallic Ferromagnetism in New Half-Heusler Compounds: an Ab Initio Study of CrTiX (X = Si,Ge, Sn,Pb)

In this work, half-metallic (HM) properties of new Half-Heusler (HH) ferromagnetic compounds CrTiX (X = Si, Ge, Sn, Pb) are studied by means of first principle band structure calculation within the framework of density functional theory (DFT). From the spin-polarized calculations using full-potential linearized augmented plane-wave (FP-LAPW)method, we found that all of these compounds are stable in ferromagnetic MgAgAs-type crystal structure. The latticeparameters of CrTiX compounds increase with increasing atomic radius of X atom and ranges from 5.76 to 6.38 Å. The calculated electronic structure of these compounds in MgAgAs-type structure shows that they are HM materials with an integer magnetic moment of 4 μ _B. Densities of states, electronic band structure, and origin of ferromagnetism have been discussed, and robust HM nature of these compounds is analyzed which makes them fascinating compounds for spintronic devices.     

Vulnerability analysis of networks to detect multiphase attacks using the actor-based language Rebeca

Increasing use of networks and their complexity make the task of security analysis more and more complicated. Accordingly, automatic verification approaches have received more attention recently. In this paper, we investigate applying of an actor-based language based on reactive objects for analyzing a network environment communicating via Transport Protocol Layer (TCP). The formal foundation of the language and available tools for model checking provide us with formal verification support. Having the model of a typical network including client and server, we show how an attacker may combine simple attacks to construct a complex multiphase attack. We use Rebeca language to model the network of hosts and its model checker to find counter-examples as violations of security of the system. Some simple attacks have been modeled in previous works in this area, here we detect these simple attacks in our model and then verify the model to find more complex attacks which may include simpler attacks as their steps. We choose Rebeca because of its powerful yet simple actor-based paradigm in modeling concurrent and distributed systems. As the real network environment is asynchronous and event-based, Rebeca can be utilized to specify and verify the asynchronous systems, including network protocols.     

Spectrophotometric determination of some vic-diol containing drugs using ion-exchange resins

Periodic acid and its salts have been widely used for the quantitative oxidation of vic-diol containing compounds including carbohydrates and catecholamine drugs. The advantage of using a polymeric resin (periodate form) over free periodate ions is that the resin quantitatively retains both unconsumed periodate ions and the iodate ions produced in the oxidation and, hence, enables one to undertake further studies on the structural, synthetic or preparative work. The resin (periodate form) was found to be a clean and sensitive chromogenic reagent for the spectrophotometric determination of some catecholamine drugs. The calibration graphs of absorption versus concentration in the range studied (5-50 ppm) were linear.     

Identification of active peptides from backbones of Nemipterus japonicus and Exocoetus volitans by electrospray ionisation–mass spectrometry

In our present investigation, Nemipterus japonicus and Exocoetus volitans backbone protein were hydrolysed by proteases like trypsin and pepsin, respectively. The protein hydrolysates were purified by different chromatographic methods, and the resulted purified peptides were analysed for their amino acid sequences by electrospray ionisation–MS/MS. The analysis of peptides showed sequences as Gly‐His‐Met‐Ser (451.8 Da) and Leu‐Glu‐Val‐Lys‐Pro (596.9 Da) for N. japonicus and E. volitans muscle, respectively. The presence of hydrophobic amino acids contributes more to the antioxidant activities of peptides than other amino acids. Moreover, sequence of amino acids in peptides plays an important role in their antioxidant activities.