Injectable Bone Cement Reinforced with Gold Nanodots Decorated rGO-Hydroxyapatite Nanocomposites,Augment Bone Regeneration

Interest in the development of new generation injectable bone cements having appropriate mechanical properties, biodegradability, and bioactivity has been rekindled with the advent of nanoscience. Injectable bone cements made with calcium sulfate (CS) are of significant interest, owing to its compatibility and optimal self-setting property. Its rapid resorption rate, lack of bioactivity, and poor mechanical strength serve as a deterrent for its wide application. Herein, a significantly improved CS-based injectable bone cement (modified calcium sulfate termed as CS_mod), reinforced with various concentrations (0–15%) of a conductive nanocomposite containing gold nanodots and nanohydroxyapatite decorated reduced graphene oxide (rGO) sheets (AuHp@rGO), and functionalized with vancomycin, is presented. The piezo-responsive cement exhibits favorable injectability and setting times, along with improved mechanical properties. The antimicrobial, osteoinductive, and osteoconductive properties of the CS_mod cement are confirmed using appropriate in vitro studies. There is an upregulation of the paracrine signaling mediated crosstalk between mesenchymal stem cells and human umbilical vein endothelial cells seeded on these cements. The ability of CS_mod to induce endothelial cell recruitment and augment bone regeneration is evidenced in relevant rat models. The results imply that the multipronged activity exhibited by the novel-CS_mod cement would be beneficial for bone repair.     

A new analytical model for switching time of a perforated MEMS switch

In this paper, the design of a low-k meander based MEMS shunt capacitive switch with perforated beam meander has been presented. A closed form analytical model to calculate the switching time of designed structure is proposed. The model is based on modified Mejis and Fokkema’s capacitance model and linearization of non-linear electrostatic force on the switch beam. The model is utilized in evaluating the switching time for uniform as well as non-uniform serpentine meander designs, considering different values of actuation voltage and a wide variation of switching parameters. This work takes into account the beam perforation, fringing field and stiffness effect simultaneously altogether. The results obtained for both the meander designs under every design specifications has been found out to be less than or approximately equal to 100 µs. These model based results are then compared with 3D FEM simulated values. Comparative Analysis indicated that the model results and simulation results are in close agreement with each other.

     

Synthesis and Characterization of Barium Lanthanum Titanates

Ternary compounds in the system BaO—TiO₂—La₂O₃ were prepared by the solid-state reaction technique at temperatures between 1300° and 1400°C using precursor oxides as the starting materials. In an alternative processing technique, BaTiO₃ was reacted with appropriate proportions of prefabricated lanthanum titanates at 1350°C to obtain the compounds. Two compounds were identified in the TiO₂-rich region of the system. The X-ray powder diffraction pattern of a compound with a chemical composition BaLa₂Ti₃O₁₀ (BaO·La₂O₃·3TiO₂) is indexed on the basis of an orthorhombic unit cell with a = 7.665 × 10⁻¹ nm, b = 28.524 × 10⁻¹ nm, and c = 3.876 × 10⁻¹ nm. The other compound, which has a chemical composition Ba₄La₈Ti₁₇O₅₀ (BaO·La₂O₃·4.25TiO₂) occurs in a narrow homogeneity range within the system. The X-ray powder diffraction pattern of the compound is indexed on the basis of an orthorhombic unit cell with a = 12.317 × 10⁻¹ nm, b = 22.394 × 10⁻¹ nm, and c = 3.881 × 10⁻¹ nm. Both the compounds are compatible with BaTiO₃ and form pseudobinary joins with BaTiO₃ in the system BaO—TiO₂—La₂O₃.     

Physicochemical Characterization of Chrysin‐Derivative‐Loaded Nanostructured Lipid Carriers with Special Reference to Anticancer Activity

Homologues long‐chain chrysin derivatives (LCD, C _n: 8–18) were synthesized and incorporated into nanostructured lipid carriers (NLC) with the aim to treat human neuroblastoma. Mutual miscibility and attractive interactions among the NLC components, namely tripalmitin (TP), cetyl palmitate (CP), oleic acid (OA), and the chrysin (CHR) derivatives (LCD) at the air–water interface were assessed by the Langmuir monolayer approach. Optimum combination for the NLC formulations was found to be 2:2:1 (M/M/M) for TP/CP/OA, respectively. NLC formulations, both in the absence and presence of LCD, were characterized by combined dynamic light scattering, electron microscopy, atomic force microscopy, and differential scanning calorimetry. The size and zeta potential of the NLC formulations were found in the range 200–350 nm and ?12 to ?18 mV, respectively. Encapsulation efficiency and release kinetics of CHR and LCD when loaded into NLC were also evaluated. LCD exhibited maximum incorporation, drug‐loading capacity, and sustained release because of its enhanced hydrophobicity. Superior incorporation efficiency and sustained‐release profile of LCD were able to enhance their anticancer activity against human neuroblastoma cell lines, compared to CHR, making them promising agents in combating cancer.     

Linear stability analysis of hydrodynamic journal bearings under micropolar lubrication

The dynamic characteristics of hydrodynamic journal bearings lubricated with micropolar fluids are presented. The modified Reynolds equation is obtained using the micropolar lubrication theory. Applying the first order perturbation of the film thickness and steady state film pressure, the dynamic characteristics in terms of the components of stiffness and damping coefficients, critical mass parameter and whirl ratio are obtained with respect to the micropolar property for varying eccentricity ratios and slenderness ratios. The results show that micropolar fluid exhibits better stability in comparison with Newtonian fluid.     

FINITE ELEMENT MODELING OF THREE-DIMENSIONAL TRANSIENT HEAT TRANSFER IN STAINLESS STEEL (304) PULSED GTA WELDMENTS

Pulsed current gas tungsten arc welding involves a large number of process parameters, and hence makes it difficult, if not impractical, to develop the procedure for a given application. A numerical model such as the finite element model will be of great use to study the effect of process parameters on heat transfer and attendant characteristics. A procedure for development of a three-dimensional transient nonlinear finite element model is presented in this article. Sensitivity analysis has been carried out to check the response of the model to constant and temperature-dependent material properties, heat loss due to vaporization of alloying elements, and total number of nodes to model the solution domain. Experimental work on thermal profiles and weld bead dimensions has been carried out to validate the results predicted by the model. Finally, parametric studies have been carried out to study the combined effects of parameters that influence the heat input.     

Tertiary treatment of distillery wastewater by nanofiltration

Tertiary treatment of aerobically treated distillery wastewater by nanofiltration was carried out in a spiral wound nanofiltration membrane module under different operating conditions. The results show that the percentage separation of organic and inorganic compounds was quite high, as reflected by the reduction of chemical oxygen demand (COD) and total dissolved solids (TDS) in the range of 96–99.5%, and 85–95% respectively. The color removal was in the range of 98–99.5%. The results of the effect of variation of the inlet concentration, feed circulation rate and pH conform to the mechanism of gel layer formation. Gel layer formation and Concentration polarization was found to play a major role in the treatment of distillery waste using nanofiltration (NF) membrane. It was observed that as concentration of feed solution increases the permeate flux was reduced. This change was higher compared to the separation of COD and TDS. The result indicates that the NF membrane showed very high performance efficiency for organic components (96–99.5%), as indicated by COD removal. In comparison, the separation of inorganic compounds was found to be in the range of 25–90% as estimated from relative separation of COD and TDS. The present study shows that nanofiltration is a promising technique for recovery of water from distillery waste, which could be used to achieve zero discharge status and solve a major environmental problem.     

Species dependent aqueous biphasic extraction of some heavy metals

A clean liquid–liquid extraction system was designed for extraction of three different heavy metals (Hg²⁺, Pb²⁺ and Bi³⁺) using an Aqueous Biphasic System consisting of a nonionic surfactant Triton X-100 in combination with two different salts viz., magnesium sulphate and sodium citrate. The extraction was monitored in two ways, by direct partitioning as well as by forming a complex with diphenylthiocarbazone (dithizone) for each metal ion in the Triton phase and measuring the colour intensity using a spectrophotometer. The change in extraction pattern at different pH of the salt rich phase was monitored. The possible change in speciation of these metal ions with pH was checked with the software programme ‘CHEAQS’ (Chemical Equilibria in Aquatic Systems). These heavy metals were also found to have higher extraction in the Triton phase when a prior complexation with dithizone was performed. The method may find extensive applications for the removal and decontaminations of the above mentioned toxic heavy metals from a sample.     

Consumption of brown rice: a potential pathway for arsenic exposure in rural Bengal

This study assesses the arsenic (As) accumulation in different varieties of rice grain, that people in rural Bengal mostly prefer for daily consumption, to estimate the potential risk of dietary As exposure through rice intake. The rice samples have been classified according to their average length (L) and L to breadth (B) ratio into four categories, such as short-bold (SB), medium-slender (MS), long-slender (LS), and extra-long slender (ELS). The brown colored rice samples fall into the SB, MS, or LS categories; while all Indian Basmati (white colored) are classified as ELS. The study indicates that the average accumulation of As in rice grain increases with a decrease of grain size (ELS: 0.04; LS: 0.10; MS: 0.16; and SB: 0.33 mg kg(-1)), however people living in the rural villages mostly prefer brown colored SB type of rice because of its lower cost. For the participants consuming SB type of brown rice, the total daily intake of inorganic As (TDI-iAs) in 29% of the cases exceeds the previous WHO recommended provisional tolerable daily intake value (2.1 μg day(-1) kg(-1) BW), and in more than 90% of cases, the As content in the drinking water equivalent to the inorganic As intake from rice consumption (C(W,eqv)) exceeds the WHO drinking water guideline of 10 μg L(-1). This study further demonstrates that participants in age groups 18-30 and 51-65 yrs are the most vulnerable to the potential health threat of dietary As exposure compared to participants of age group 31-50 yrs, because of higher amounts of brown rice consumption patterns and lower BMI.