Titanium machining with new plasma boronized cutting tools

Titanium is a commonly used material in various critical applications such as aerospace and biomedical applications. In this article, for the first time in the literature, development and implementation of a novel plasma boronizing process on Tungsten Carbide (WC) cutting tools is introduced. Plasma boronizing on WC tools is performed with gas combination of 10% BF₃, 40% Argon and 50% H₂ at different temperatures and durations. Performance enhancements of plasma boronized WC tools on Titanium (Ti-6Al-4V) machining are investigated under various cutting conditions. It is found that new plasma boronizing of WC is a very cost effective solution for significantly increasing tool life in Titanium machining.     

A predicted three-dimensional structure for the human immunodeficiency virus binding domains of CD4 antigen

A predicted three-dimensional structure of the two N-terminalextracellular domains of human CD4 antigen, a cell surface glycoprotein,is reported. This region of CD4, particularly the first domain,has been identified as containing the binding region for theenvelope gp120 protein of the human immuno-deficiency virus.The model was predicted based on the sequence homology of eachdomain with the variable light chain of immunoglobulins. Theframework ß-sheet regions were taken from the crystalcoordinates of REI. For one region in the first domain of CD4there was an ambiguity in the alignment with REI and two alternatemodels are presented. Loops connecting the framework were modeledfrom fragments selected from a database of main chain coordinatesfrom all known protein structures. Residues identified as involvedin binding gp120 have been located in several other studieswithin the first domain of CD4. Epitopes from eight monoclonalantibodies have been mapped onto residues in both domains. Competitionof these antibodies with each other and with gp120 can be interpretedfrom the structural model.     

An Environmentally Benign,Highly Efficient Catalytic Reduction of p‐Nitrophenol using a Nano‐Sized Nickel Catalyst Supported on Silica‐Alumina

A green and effective method is reported for the reduction of p‐nitrophenol to p‐aminophenol using a nano‐sized nickel catalyst supported on silica‐alumina in the presence of hydrazine hydrate as an alternative source of hydrogen. It was found that nickel loaded on a silica‐alumina support is a very effective catalyst in the hydrogenation of p‐nitrophenol to p‐aminophenol. Thus it attained 100% conversion in only 69 seconds instead of 260 seconds for commercial Raney nickel. In addition, the possibility to reuse it more than one time with great efficiency gives it another advantage over commercial Rainey nickel which cannot be used more than once. This economical and environmentally friendly method provides a potentially new approach for the synthesis of the intermediate product of paracetamol in industry, which overcomes the drawbacks of the known reduction methods. The prepared catalysts were fully characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X‐ray (EDX), and electron spin resonance (ESR) tehniques.     

Screening of β1- and β2-Adrenergic Receptor Modulators through Advanced Pharmacoinformatics and Machine Learning Approaches

Cardiovascular diseases (CDs) are a major concern in the human race and one of the leading causes of death worldwide. β-Adrenergic receptors (β1-AR and β2-AR) play a crucial role in the overall regulation of cardiac function. In the present study, structure-based virtual screening, machine learning (ML), and a ligand-based similarity search were conducted for the PubChem database against both β1- and β2-AR. Initially, all docked molecules were screened using the threshold binding energy value. Molecules with a better binding affinity were further used for segregation as active and inactive through ML. The pharmacokinetic assessment was carried out on molecules retained in the above step. Further, similarity searching of the ChEMBL and DrugBank databases was performed. From detailed analysis of the above data, four compounds for each of β1- and β2-AR were found to be promising in nature. A number of critical ligand-binding amino acids formed potential hydrogen bonds and hydrophobic interactions. Finally, a molecular dynamics (MD) simulation study of each molecule bound with the respective target was performed. A number of parameters obtained from the MD simulation trajectories were calculated and substantiated the stability between the protein-ligand complex. Hence, it can be postulated that the final molecules might be crucial for CDs subjected to experimental validation.     

Effect of Varying Amount of Polyethylene Glycol (PEG-600) and 3-Aminopropyltriethoxysilane on the Properties of Chitosan based Reverse Osmosis Membranes

Chitosan and polyethylene glycol (PEG-600) membranes were synthesized and crosslinked with 3-aminopropyltriethoxysilane (APTES). The main purpose of this research work is to synthesize RO membranes which can be used to provide desalinated water for drinking, industrial and agricultural purposes. Hydrogen bonding between chitosan and PEG was confirmed by displacement of the hydroxyl absorption peak at 3237 cm⁻¹ in pure chitosan to lower values in crosslinked membranes by using FTIR. Dynamic mechanical analysis revealed that PEG lowers Tg of the modified membranes vs. pure chitosan from 128.5 °C in control to 120 °C in CS-PEG5. SEM results highlighted porous and anisotropic structure of crosslinked membranes. As the amount of PEG was increased, hydrophilicity of membranes was increased and water absorption increased up to a maximum of 67.34%. Permeation data showed that flux and salt rejection value of the modified membranes was increased up to a maximum of 80% and 40.4%, respectively. Modified films have antibacterial properties against Escherichia coli as compared to control membranes.     

Performance tuning of glass fiber/epoxy composites through interfacial modification upon integrating with dendrimer functionalized graphene oxide

In this study, glass fiber/epoxy composites were interfacially tailored by introducing polyamidoamine (PAM) dendrimer functionalized graphene oxide (GO) into epoxy matrix. Two different composites each containing varying loading fraction (0.5, 1.0, and 1.5 wt%) of GO and GO-PAM were fabricated via hot press processing. Composites were evaluated for interlaminar shear strength (ILSS), dynamic mechanical properties and thermal conductivity. The inclusion of 1.5 wt% GO-PAM resulted ~57.3%, ~42.7%, and ~54% enhancement in ILSS, storage modulus and thermal conductivity, respectively. Almost, ~71% reduction in coefficient of thermal expansion was also observed at same GO-PAM loading. Moreover, higher glass transition temperature was observed with GO-PAM addition. GO-PAM substantially improved fiber/matrix interfacial adhesion, which was witnessed through scanning electron microscopy. The enhanced thermo-mechanical performance was attributed to interfacial covalent interactions engendered by ring opening reaction between epoxy and amine moieties of PAM dendrimers. These multiscale composites with extraordinary functional properties can outperform conventional counterparts with improved reliability and performance.     

PRP4 Promotes Skin Cancer by Inhibiting Production of Melanin,Blocking Influx of Extracellular Calcium,and Remodeling Cell Actin Cytoskeleton

Pre-mRNA processing factor 4B (PRP4) has previously been shown to induce epithelial-mesenchymal transition (EMT) and drug resistance in cancer cell lines. As melanin plays an important photoprotective role in the risk of sun-induced skin cancers, we have investigated whether PRP4 can induce drug resistance and regulate melanin biosynthesis in a murine melanoma (B16F10) cell line. Cells were incubated with a crucial melanogenesis stimulator, alpha-melanocyte-stimulating hormone, followed by transfection with PRP4. This resulted in the inhibition of the production of melanin via the downregulation of adenylyl cyclase-cyclic adenosine 3′,5′-monophosphate (AC)–(cAMP)–tyrosinase synthesis signaling pathway. Inhibition of melanin production by PRP4 leads to the promotion of carcinogenesis and induced drug resistance in B16F10 cells. Additionally, PRP4 overexpression upregulated the expression of β-arrestin 1 and desensitized the extracellular calcium-sensing receptor (CaSR), which in turn, inhibited the influx of extracellular Ca²⁺ ions. The decreased influx of Ca²⁺ was confirmed by a decreased expression level of calmodulin. We have demonstrated that transient receptor potential cation channel subfamily C member 1 was involved in the influx of CaSR-induced Ca²⁺ via a decreasing level of its expression. Furthermore, PRP4 overexpression downregulated the expression of AC, decreased the synthesis of cAMP, and modulated the actin cytoskeleton by inhibiting the expression of Ras homolog family member A (RhoA). Our investigation suggests that PRP4 inhibits the production of melanin in B16F10 cells, blocks the influx of Ca²⁺ through desensitization of CaSR, and modulates the actin cytoskeleton through downregulating the AC–cAMP pathway; taken together, these observations collectively lead to the promotion of skin carcinogenesis.     

The Pupal Parasitoid Trichopria drosophilae Is Attracted to the Same Yeast Volatiles as Its Adult Host

Journal of Chemical Ecology - There is increasing evidence that microorganisms, particularly fungi and bacteria, emit volatile compounds that mediate the foraging behaviour of insects and therefore...     

Characterization of the structure and properties of processed alumina-graphene and alumina-zirconia composites

The onset of hybrid alumina-based composites, which combines two or more nano-particles within the alumina matrix has already shown promising improvements in the matrix material. However, variations in mechanical properties including the optimum compositions that give improved properties faced with the development of alumina-based composites require further studies to understand the underlying mechanisms and synergistic effects of the nano-particle additions on the alumina matrix. In the current study, the structure and properties of Al?O?-graphene (0.5 wt%) and Al?O?–ZrO? (4 wt% and 10 wt%) composites fabricated via hot-pressing was studied as a baseline for multiple combinations. Even though the addition of 10 wt%ZrO? resulted in a 23% reduction in the grain size of the alumina matrix, the 4 wt%ZrO? addition resulted in a 14% increase in grain size as compared to the parent alumina matrix. X-ray diffraction analysis revealed that there was approximately 85% monoclinic (m-ZrO₂) vs. 15% tetragonal (t-ZrO₂) crystal structures in the A4ZrO? sample whilst the A₁₀ZrO? had approximately 93% m-ZrO₂ vs. 7% t-ZrO₂. The high-volume fraction of the monoclinic crystal structures in the A₁₀ZrO? accounts for the induced microcracks in the sample since the transition from the ductile-tetragonal to brittle-monoclinic is associated with the exertion of compressive stresses on the alumina matrix by the associated elastic volume expansion of m-ZrO₂. Also, the addition of 0.5 wt%graphene resulted in about 37% reduction in the grain size of the alumina matrix, and approximately 10% increase in hardness as a result of the distribution of graphene along the grain boundaries of the parent alumina matrix, which restricts grain coalescence and growth during processing. Furthermore, an increase up to 115% and 164% were observed in the fracture toughness (K_IC) with the inclusion of 0.5 wt%graphene and 10 wt%ZrO? respectively, which was primarily ascribed to the fine-grained microstructures and toughening mechanisms of the intergranular graphene and ZrO? particles.     

Chinese Cabbage (Brassica campestris L.) does not Improve Glucose Tolerance,Serum Insulin,or Blood Lipid Profiles in a Rat Model of Type‐2 Diabetes

ABSTRACT: The present study was conducted to investigate the effects of a low (0.5%) and a high (2.0%) dietary dose of freeze‐dried Chinese cabbage (CC) (Brassica campestris L.) powder in a type‐2 diabetes (T2D) model of rats. Five‐week‐old male Sprague–Dawley rats were fed a high fat (HF)‐containing diet for 2 wk then randomly divided into 4 groups of 8 animals, namely: normal control (NC), diabetic control (DBC), Chinese cabbage low (CCL, 0.5%), and Chinese cabbage high (CCH, 2.0%) groups. Diabetes was induced by an intraperitoneal injection of streptozotocin (STZ; 40 mg/kg body weight) in all groups except the NC group. After 4 wk feeding of experimental diets, although food intake was not different among the DBC, CCL, and CCH groups, body weight gain was significantly (P < 0.05) higher in the CCH group compared to the DBC group. Relatively higher serum insulin concentrations and better glucose tolerance were observed in the CC‐fed groups compared to the DBC group; however, the results were not significantly different. Fasting blood glucose, blood glycated hemoglobin (HbA1c), liver weight, and liver glycogen levels were not influenced by the CC‐containing diets. Additionally, hypertriglyceridemic tendencies were observed in the CC‐fed groups compared to the NC and DBC groups, while difference observed for total‐, HDL‐, and LDL‐cholesterols between the groups were negligible. Results of this study suggest that up to 2% dietary dose of freeze‐dried CC is not significantly effective to reduce diabetes‐related symptoms in an HF diet‐fed STZ‐induced T2D model of rats.