Numerical studies of viscous stagnation point flows

A rapid finite-difference procedure for computing stagnation point flows at a given Reynolds number in terms of stream function and vorticity distributions is described. The method is illustrated for spherical and cylindrical curvature for Reynolds number ranges of 1 ≤ Re ≤ 400 and 4 ≤ Re ≤ 100 respectively. Predicted radial and angular velocity distributions in the frontal region are compared with results from numerical solutions of the full elliptic equations of motion. The use of a modified potential flow outer boundary condition reduces the region of numerical computation.     

A Short Review on Copper Calcium Titanate (CCTO) Electroceramic: Synthesis,Dielectric Properties,Film Deposition,and Sensing Application

Nano-Micro Letters - Electroceramic calcium copper titanates (CaCu3Ti4O12, CCTO), with high dielectric permittivities (ε) of approximately 105 and 104, respectively, for single crystal and...     

Natural Palm Olein Polyol as a Replacement for Polyether Polyols in Viscoelastic Polyurethane Foam

The impact of replacing three polyether polyols with different levels of a single palm olein‐based natural oil polyol (NOP) was systematically correlated with the changes in foaming reactivity, cell structure, physico‐mechanical properties, and morphology of viscoelastic (VE) foams. The data show that replacing the polyether polyols with the NOP slightly increased the rate of the foaming reactivity. Increasing the NOP content resulted in increased cell size and cells remained fully open. Increased NOP content contributed to higher load bearing properties of VE foam, which can be attributed to higher functionality of NOP compared to polyether polyols. Addition of the NOP slightly increased the resilience of the foams, however, the hysteresis which is the measure of energy absorption remained mostly unaffected. Age properties, characterized by dry and humid compression sets, were mostly unaffected by the replacement of the polyether polyol with the NOP. The addition of NOP did not impact the morphology of the VE foam polymer matrix, which appears to retain a low degree of hard and soft segment domain separation. Overall, the results demonstrate a feasibility that the NOP can be used to partially replace the polyether polyols in VE polyurethane foams without significant impact on the functional performance.     

Morpho-anatomical characterization of some members of euglenophycota (algae) of north-east Punjab,Pakistan based on light microscopy (LM) and scanning electron microscopy (SEM)

The study was carried out in four districts, that is, Gujranwala, Gujarat, Narowal and Sialkot of Punjab, Pakistan. The sampling was carried out randomly in different seasons from the water bodies especially from wastewater. Twenty-one species belonging to Euglenophycota were identified using light microscopy and scanning electron microscopy from which 04 species belong to genus Phacus, 02 species belonging to Trachelomonas and Euglena based on light microscopy. It was observed that Euglena was the most diverse genus and it is supposed to be the indicator species of the polluted water. It was observed that E. oblonga was found in maximum pH range, that is, 7.0–11.0. Similarly, E. brevicaudatus was found in maximum EC, that is, 169 ± 1.5 ms/cm these outcomes indicated that for internal examination along with LM, SEM was necessary for correct identification of algal sample up to specie level.     

Studies on the formation of yttrium iron garnet (YIG) through stoichiometry modification prepared by conventional solid-state method

Y₃Fe₅O₁₂ (YIG) prepared by conventional solid-state method can rarely be of high purity. However, this study suggests that high purity YIG can be produced via conventional solid-state methods, through stoichiometry modification. This is achieved by adding various amounts of excess Fe₂O₃ to control the YIG stoichiometric ratios. In this work, ferrite and yttria were calcined at 1100 °C (for 8 h) and sintered at 1420 °C (6 h). In most samples, the formation of YIG, with YFeO₃ (YIP) and/or Fe₂O₃ as associated phases were detected. Uniform microstructures of YIG are also observed. YIP phase in YIG is found to be inversely related to the addition of excess Fe₂O₃, up to 8 wt%. At above 8 wt% Fe₂O₃ addition, YIP disappears, leaving unreacted excess Fe₂O₃ as a new associated phase. From the investigation, it is safe to conclude that the purity of YIG can be increased with the addition of excess Fe₂O₃.     

Toxicity and Metabolism of Layered Double Hydroxide Intercalated with Levodopa in a Parkinson’s Disease Model

Layered hydroxide nanoparticles are generally biocompatible, and less toxic than most inorganic nanoparticles, making them an acceptable alternative drug delivery system. Due to growing concern over animal welfare and the expense of in vivo experiments both the public and the government are interested to find alternatives to animal testing. The toxicity potential of zinc aluminum layered hydroxide (ZAL) nanocomposite containing anti-Parkinsonian agent may be determined using a PC 12 cell model. ZAL nanocomposite demonstrated a decreased cytotoxic effect when compared to levodopa on PC12 cells with more than 80% cell viability at 100 μg/mL compared to less than 20% cell viability in a direct levodopa exposure. Neither levodopa-loaded nanocomposite nor the un-intercalated nanocomposite disturbed the cytoskeletal structure of the neurogenic cells at their IC₅₀ concentration. Levodopa metabolite (HVA) released from the nanocomposite demonstrated the slow sustained and controlled release character of layered hydroxide nanoparticles unlike the burst uptake and release system shown with pure levodopa treatment.     

Succinate and malate improve development of hamster eight-cell embryos in vitro: confirmation of viability by embryo transfer

The in vitro development of hamster preimplantation embryos is supported by non-glucose energy substrates. To investigate the importance of embryonic metabolism, influence of succinate and malate on the development of hamster 8-cell embryos to blastocysts was examined using a chemically defined protein-free modified hamster embryo culture medium-2 (HECM-2m). There was a dose-dependent influence of succinate on blastocyst development; 0.5 mM succinate was optimal (85.1% +/- 3.9 vs. 54.5% +/- 3.5). In succinate-supplemented HECM-2m, blastocyst development was reduced by omission of lactate (68.5% +/- 7.2), but not pyruvate (85.8% +/- 6.2) or glutamine (84.1% +/- 2.1). Succinate along with either glutamine or lactate or pyruvate poorly supported blastocyst development (28%-58%). Malate also stimulated blastocyst development; 0.01 mM malate was optimal (86.3% +/- 2.8). Supplementation of both succinate and malate to HECM-2m supported maximal (100%) blastocyst development, which was inhibited 4-fold by the addition of glucose/phosphate. The mean cell numbers (MCN) of blastocysts cultured in succinate-supplemented HECM-2m was higher (28.3 +/- 1.1) than it was for those cultured in the absence of glutamine or pyruvate (range 20-24). The MCN was the highest (33.4 +/- 1.6) for blastocysts cultured in succinate-malate-supplemented HECM-2m followed by those in succinate (28.3 +/- 1.1) or malate (24.7 +/- 0.5) supplemented HECM-2m. Embryo transfer experiments showed that 29.8% (+/- 4.5) of transferred blastocysts cultured in succinate-malate-supplemented HECM-2m produced live births, similar (P > 0.1) to the control transfers of freshly recovered 8-cells (33.5% +/- 2.0) or blastocysts (28.9% +/- 3.0). These data show that supplementation of succinate and malate to HECM-2m supports 100% development of hamster 8-cell embryos to high quality viable blastocysts and that non-glucose oxidizable energy substrates are the most preferred components in hamster embryo culture medium.     

Fewer bone histomorphometric abnormalities with intermittent than with continuous slow-release sodium fluoride therapy

To help resolve the uncertainty whether sodium fluoride (NaF) therapy should be given intermittently or continuously, we examined iliac crest bone biopsies (before and after treatment) and fragility fracture rates in 35 intermittently treated (group I) and 69 continuously treated (group C) patients; all received calcium. The following statistically significant results were obtained. Reduction in vertebral fracture rate was similar in the two groups. Trabecular thickness and the structurally more important mineralized thickness increased only in group I. Group I also accumulated less excess osteoid (surface, volume). Mean osteoid thickness did not change in either group because of a bimodal distribution of wide seams with osteoblasts and double tetracycline labels, and thin seams without osteoblasts or labels. Osteoid was lamellar. Osteoid in abnormal sites (within bone marrow or bone, or around osteocytes) was found less frequently in group I. Adjusted apposition rate declined and mineralization lag time increased in both groups because of extended unlabelled osteoid seams. Erosion surface increased only in group C. Hook and/or tunnel erosion was seen less frequently in group I; it was closely associated with osteoid in abnormal sites and correlated with osteoid surface. Extended osteoid surface may have forced osteoclasts to hollow out trabeculae, leaving the empty osteoid shell in marrow. Excess osteoid volume and eroded surface and osteoid and erosion in abnormal sites correlated with bone fragility in group C. We conclude that intermittent therapy is to be preferred because it (1) increased mineralized trabecular thickness, (2) did not cause excessive osteoid accumulation and erosion, (3) showed less osteoid and erosion in abnormal sites and (4) led to a similar reduction in the vertebral fracture rate as did continuous treatment. The question of whether intermittency of therapy has some other effect independent of the cumulative dose of fluoride administered cannot be answered by this study.     

Rainfall propagation impairments for medium elevation angle satellite‐to‐earth 12 GHz in the tropics

Rain attenuation is the dominant propagation impairment for satellite communication systems operating at frequencies above about 10 GHz. The rainfall path attenuation at 12.255 GHz measured at Universiti Sains Malaysia (USM) for 4 years (2 January to 5 December) is presented. This paper presents an empirical analysis of rain rate and rain attenuation cumulative distribution functions obtained using 1‐min integrated rainfall data and comparison of the measured data with data obtained from well‐established rain model attenuation predictions. Copyright © 2008 John Wiley & Sons, Ltd.