Heat Transfer Phenomena of Assemblages of Smooth Slip Spheres in Newtonian Fluids

Combined effects of slip velocity and volume fraction of slip spheres on the heat transfer characteristics of multiple slip spheres are numerically investigated within the framework of a free surface cell model combined with a linear slip velocity along the surface of the slip spheres. The governing conservation equations of the mass, momentum, and energy are solved by a segregated approach using a simplified marker and cell algorithm implemented on a staggered grid arrangement in spherical coordinates. The convection and diffusion terms of conservation equations are discretized using quadratic upstream interpolation for convective kinematics and second‐order central differencing schemes, respectively. Prior to obtaining new results, this numerical solver is validated by comparison of present results with the existing literature values. Further new results are obtained for a range of conditions as; Reynolds number, Re: 0.1–200; Prandtl number, Pr: 1–100; volume fraction of slip spheres, Φ: 0.1–0.5 and slip parameter, λ: 0.01–100. The effects of these dimensionless parameters on isotherm contours and local and average Nusselt numbers are thoroughly delineated. Finally, a new empirical correlation for the average Nusselt number of multiple smooth slip spheres is proposed on the basis of present numerical results.     

The role of functionalized carbon nanotubes in a PA6/LCP blend

Multi-walled carbon nanotubes (MWCNTs) were carboxyl-functionalized in order to improve their dispersion in a polymer matrix. The carboxyl-functionalized MWCNTs (i.e., MWCNT-COOH) were added into a blend matrix consisting of polyamide 6 (PA6) and liquid crystalline polymer (LCP) (PA6:LCP = 80:20 in weight) to make ternary composites. The effects of MWCNT-COOH on the rheological, physical, morphological, thermal, mechanical, and electrical properties of the ternary composites have been examined systematically. The dispersion of MWCNTs in the polymer matrix and their interactions with the polymers (i.e., PA6 and LCP) were found to be the most important factors affecting all properties. The functionalization of MWCNTs resulted in the significant improvement in their dispersion in the polymer matrix and largely enhanced the interactions of MWCNTs with the polymer matrix. The functionalized MWCNTs acted not only as reinforcement fillers but also as a compatibilizer that could enhance the interfacial adhesion between PA6 and LCP. Interestingly, the packing density of the polymer matrix was greatly increased by adding MWCNT-COOH.     

Transient virulence of emerging pathogens

Should emerging pathogens be unusually virulent? If so, why? Existing theories of virulence evolution based on a tradeoff between high transmission rates and long infectious periods imply that epidemic growth conditions will select for higher virulence, possibly leading to a transient peak in virulence near the beginning of an epidemic. This transient selection could lead to high virulence in emerging pathogens. Using a simple model of the epidemiological and evolutionary dynamics of emerging pathogens, along with rough estimates of parameters for pathogens such as severe acute respiratory syndrome, West Nile virus and myxomatosis, we estimated the potential magnitude and timing of such transient virulence peaks. Pathogens that are moderately evolvable, highly transmissible, and highly virulent at equilibrium could briefly double their virulence during an epidemic; thus, epidemic-phase selection could contribute significantly to the virulence of emerging pathogens. In order to further assess the potential significance of this mechanism, we bring together data from the literature for the shapes of tradeoff curves for several pathogens (myxomatosis, HIV, and a parasite of Daphnia) and the level of genetic variation for virulence for one (myxomatosis). We discuss the need for better data on tradeoff curves and genetic variance in order to evaluate the plausibility of various scenarios of virulence evolution.     

Instrumental texture and flavonoid profile of paste developed from sprouted onion varieties of Indian origin

The effect of sprouting on the instrumental texture, antioxidant activity, and ?avonoid pro?le of the paste prepared from four Indian onion varieties (Punjab White, Punjab Naroya, PRO-6, and Commercial) was studied. The significant (P ? 0.05) effect of sprouting on microstructure, firmness, adhesiveness, gumminess, and chewiness in paste samples from all varieties was observed. There was significant decrease (P ? 0.05) in lightness with consequent significant (P ? 0.05) increase in redness, greenness, and yellowness in paste samples which was due to the increase in anthocyanin content with sprouting. The paste samples from sprouted onion varieties also showed an increase in phenol content, flavonoid content, antioxidant capacity, and DPPH radical scavenging activity. The HPLC analysis revealed an increase in total flavonoids in pastes from PRO-6 and Punjab Naroya varieties. Thus, present study implied that sprouting could be beneficial as it enhanced the functional potential of onion pastes.     

Machinability Study of Stir Cast Hypoeutectic Aluminum-Silicon Alloys During Turning

The influence of Be and Cd (iron correctors) on mechanical properties and machining behavior of hypoeutectic Al-Si alloy (Al-7Si-0.5Mg-1.2Fe) processed by conventional and semi-solid metal (SSM) processing (stir casting) techniques is investigated. The alloys under investigation were prepared by controlling melt in an induction melting furnace. The stirring of SSM was carried out at a constant stirring speed of 400 rpm under constant cooling conditions from liquidus temperature. The turning operations were carried out under dry conditions on a CNC turning center using coated-carbide insert by varying cutting speed, feed rate, depth of cut, and approaching angle. An orthogonal array, the signal-to-noise ratio, and analysis of variance were employed to study the machining performance characteristics. The results indicate that Be/Cd modification of the alloy and selected cutting parameters significantly affect the machining characteristics. The feed rate, cutting speed, and Cd as an iron corrector have more effect on the machining behavior of the alloys under study.     

Mechanical Performance of Soy‐Hull‐Reinforced Bioplastic Green Composites: A Comparison with Polypropylene Composites

A blend composition of poly(3‐hydroxybutyrate‐co‐valerate) and polylactide is used as a bioplastic matrix and reinforced with soy hull to engineer novel green composites. A comparative study with soy‐hull‐reinforced polypropylene composite system is performed. A compatibilizer is used to engineer the novel class of green composites with a balanced stiffness and toughness performance with the target to substitute PP‐based composites. The flexural and impact strength along with hydrophobicity of compatibilized composites are improved significantly over the noncompatibilized counterpart. The fiber/matrix interaction is investigated by SEM. These green composites have the potential to substitute PP‐based composites in some applications.

     

Chitosan-functionalized graphene oxide as a nanocarrier for drug and gene delivery

The covalent functionalization of graphene oxide (GO) with chitosan (CS) is successfully accomplished via a facile amidation process. The CS-grafted GO (GO-CS) sheets consist of about 64 wt.% CS, which imparts them with a good aqueous solubility and biocompatibility. Additionally, the physicochemical properties of GO-CS are studied. As a novel nanocarrier, GO-CS is applied to load a water-insoluble anticancer drug, camptothecin (CPT), via π-π stacking and hydrophobic interactions. It is demonstrated that GO-CS possesses a superior loading capacity for CPT, and the GO-CS-CPT complexes show remarkably high cytotoxicity in HepG2 and HeLa cell lines compared to the pure drug. At the same time, GO-CS is also able to condense plasmid DNA into stable, nanosized complexes, and the resulting GO-CS/pDNA nanoparticles exhibit reasonable transfection efficiency in HeLa cells at certain nitrogen/phosphate ratios. Therefore, the GO-CS nanocarrier is able to load and deliver both anticancer drugs and genes.     

Studies on the composition,quality and processing of triticale Part 3. Rheological and baking properties

Studies on rheological and baking properties of 14 promising strains of triticale and two check wheat varieties from India are reported. The farinograms obtained from triticale flours, in general, revealed poor dough development time and lower stability than those from wheat flours. The mean water absorption capacity of triticale flours was 54.3 percent compared to 64.4 percent of wheat flour. The triticale flour produced poor loaf volumes with mean value of 399 cm³ compared to 475 cm³ of wheat flour. Cookie baking tests showed that triticale flours were eminently suited for this purpose because of their soft flour and weaker gluten. Triticale whole meal required much less water for preparation of dough for chapatis and produced red coloured chapatis which tended to stale faster.     

Effect of gum arabic concentration and inlet temperature during spray drying on physical and antioxidant properties of honey powder

The research studied the effect of gum arabic concentration at 35, 40 and 45 % with inlet temperatures of 160, 170 and 180 °C on the physico-chemical, functional and thermal properties of honey powder enriched with aonla (Emblica officinalis. Gaertn) and basil (Ocimum sanctum) extract, wherein other parameters like concentration of aonla extract (8 %), basil extract (6 %) and feed rate (0.11 mL/s) were kept as constant. Powder recovery and glass transition temperature (T_g) showed significant increase with the increase in inlet temperatures. On the other hand hygroscopicity, tapped density, total phenolic content, antioxidant activity and vitamin C content showed inverse response to the increase in inlet temperatures. However powder recovery, T_g, total phenolic content, antioxidant activity and vitamin C content increased with the increase in concentration of gum arabic. On the basis of obtained results it can be concluded that honey powder with the concentration of 45 % gum arabic at 170 °C inlet temperature was found to be less hygroscopic with better powder recovery and overwhelming antioxidant properties.