Effect of Surface Modification on Flow Properties and Pressure Filtration of Alumina Slurries

ABSTRACT

The purpose of this research is to evaluate the effectiveness of various dispersants in fine particle processing. The surface of alumina in aqueous solution was modified by using both non-ionic and ionic surfactants. The rheological properties of highly loaded alumina suspensions were studied as a function of surfactant concentration. Pressure filtration experiments were also carried out in order to evaluate the dispersion properties and consolidation behavior. The pressure filtration results could be used to distinguish between well-dispersed and flocculated slurries. The results of rheology measurements and pressure filtration experiments are interpreted using suitable models. To assist the analysis, electrokinetic sonic amplitude (ESA) technique was used for characterization of electrical double layer.     

Comparison of antibacterial activity of Ag nanoparticles synthesized from leaf extract of Parthenium hystrophorus L in aqueous media and Gentamicin sulphate: in-vitro

Monodisperse silver (Ag) nanoparticles were synthesized by using Parthenium hystrophorus L leaf extract in aqueous media. The synthesized nanoparticles were characterized by using UV-vis spectrophotometer, X-ray diffracto-meter (XRD), transmission electron microscope (TEM), and dynamics light scattering (DLS). Size-dependent antibacterial activities of Ag nanoparticles were tested against Gram negative Pseudomonas aeruginosa and Gram positive Staphylococcus aureus. Ag nanoparticles having 20?±?2?nm size in diameter show maximum zone of inhibition (23?±?2.2?mm) in comparison to 40?nm and 70?nm diameter nanoparticles for Pseudomonas aeruginosa. The zone of inhibition against Staphylococcus aureus were 19?±?1.8?mm, 15?±?1.5?mm and 11?±?1?mm for 20?nm, 40?nm, and 70?nm, respectively. In addition, affect of concentration of 20?nm size Ag nanoparticles on Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus species were also reported and results were compared with 10?µg/ml dose of Gentamicin sulphate. The Parthenium hystrophorus L leaf extract capped 20?±?2?nm Ag nanoparticles (7.5?µg/ml) shows statistically significant antibacterial activity than Gentamicin sulphate (10?µg/ml) against Staphylococcus aureus.     

Effect of irradiated chitosan on the rancidity of radiation-processed lamb meat

We report here the production of irradiated chitosan and its novel use as a natural antioxidant for minimising lipid peroxidation of radiation‐processed lamb meat. Antioxidant activity of chitosan isolated from shrimp waste was determined by the beta‐carotene bleaching assay and 1,1‐Diphenyl‐2‐picrylhydrazyl (DPPH) scavenging activity. Irradiation of chitosan at 25 kGy dose of gamma radiation resulted in a six‐fold increase in its antioxidant activity as compared to the non‐irradiated chitosan as measured by DPPH assay. Similarly the reducing power of irradiated chitosan was 6‐fold greater than autoclaved chitosan. The suitability of irradiated chitosan for controlling lipid oxidation of radiation‐processed meat was also investigated. Irradiated chitosan when added to meat before radiation processing was found to be more effective in minimising lipid perioxidation than non‐irradiated chitosan as measured by TBA number and carbonyl content. TBA values of irradiated meat containing irradiated chitosan decreased by 88% (leg) and 54% (rib) as compared to the corresponding sample without chitosan. Further development of post‐processing rancidity was reduced by 39% (leg) and 59% (rib) in the samples treated with chitosan as compared to non‐treated controls even after a week of storage at 0–3°C.     

Prevalence of enterococci in frozen dairy products and their pathogenicity

Enterococci were present in all the samples of frozen dairy products examined in the present study. The total bacterial counts as well as enterococcal counts were generally very high in Kulfi (a frozen product similar to ice cream) and Kulfi mix. Among 161 enterococcal isolates recovered, the predominant type was Streptococcus faecalis var. faecalis, the majority of isolates coming from Kulfi and Kulfi mix samples. Although 58 cultures produced deoxyribonuclease, only two of them exhibited thermonuclease (TNase) production. Hyaluronidase activity was shown by three strains. However, 31 strains were alpha haemolytic, while five showed beta haemolysis on rabbit blood agar. Out of these haemolytic strains tested, 21 produced lethal toxicity in mice and 20 strains showed culture virulence, postmortem studies revealed congestion of heart, liver, kidney and spleen. The two TNase positive strains of Streptococcus faecium produced fluid accumulation in ligated ileal loops of rabbits and distension in the gastrointestinal tracts of infant mice.     

Shelf-stable and safe intermediate-moisture meat products using hurdle technology

A number of ready-to-use shelf-stable intermediate-moisture (IM) spiced mutton and spiced chicken products were developed with a combination of hurdles (reduced moisture, vacuum packing, and irradiation). The water activity of the products was reduced to about 0.80 either by grilling or by hot-air drying. These IM products were vacuum packed and subjected to gamma radiation processing at 0 to 10 kGy. Microbiological analyses revealed a radiation dose-dependent reduction in total viable counts and in numbers of Staphylococcus species. IM meat products that did not undergo radiation treatment showed visible mold growth within 2 months. The products subjected to irradiation at 10 kGy showed an absence of viable microorganisms and also retained high sensory acceptability for up to 9 months at ambient temperatures.     

Flame Retardants-Mediated Interferon Signaling in the Pathogenesis of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is a growing concern worldwide, affecting 25% of the global population. NAFLD is a multifactorial disease with a broad spectrum of pathology includes steatosis, which gradually progresses to a more severe condition such as nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and eventually leads to hepatic cancer. Several risk factors, including exposure to environmental toxicants, are involved in the development and progression of NAFLD. Environmental factors may promote the development and progression of NAFLD by various biological alterations, including mitochondrial dysfunction, reactive oxygen species production, nuclear receptors dysregulation, and interference in inflammatory and immune-mediated signaling. Moreover, environmental contaminants can influence immune responses by impairing the immune system’s components and, ultimately, disease susceptibility. Flame retardants (FRs) are anthropogenic chemicals or mixtures that are being used to inhibit or delay the spread of fire. FRs have been employed in several household and outdoor products; therefore, human exposure is unavoidable. In this review, we summarized the potential mechanisms of FRs-associated immune and inflammatory signaling and their possible contribution to the development and progression of NAFLD, with an emphasis on FRs-mediated interferon signaling. Knowledge gaps are identified, and emerging pharmacotherapeutic molecules targeting the immune and inflammatory signaling for NAFLD are also discussed.     

Catalyst and its diameter dependent growth kinetics of CVD grown GaN nanowires

GaN nanowires were grown using chemical vapor deposition with controlled aspect ratio. The catalyst and catalyst-diameter dependent growth kinetics is investigated in detail. We first discuss gold catalyst diameter dependent growth kinetics and subsequently compare with nickel and palladium catalyst. For different diameters of gold catalyst there was hardly any variation in the length of the nanowires but for other catalysts with different diameter a strong length variation of the nanowires was observed. We calculated the critical diameter dependence on adatoms pressure inside the reactor and inside the catalytic particle. This gives an increasing trend in critical diameter as per the order gold, nickel and palladium for the current set of experimental conditions. Based on the critical diameter, with gold and nickel catalyst the nanowire growth was understood to be governed by limited surface diffusion of adatoms and by Gibbs–Thomson effect for the palladium catalyst.     

Thickness Dependent Physical Properties of Thermally Evaporated Nanocrystalline CdSe Thin Films

This paper presents a study on thickness dependent physical properties of cadmium selenide thin films. The films of thickness 445, 631 and 810 nm were deposited employing thermal evaporation technique on glass and ITO-coated glass substrates followed by thermal annealing in air atmosphere at 200 °C. These films were subjected to X-ray diffractometer, UV–Vis spectrophotometer, scanning electron microscopy(SEM) and electrometer for structural, optical,surface morphological and electrical analysis respectively. The structural analysis reveals that the films are nanocrystalline in nature with cubic phase and preferred orientation(111). The crystallographic parameters such as lattice constant, interplanar spacing, grain size, internal strain, dislocation density, number of crystallites per unit area and texture coefficient are calculated and discussed. The optical band gap is found in the range 1.75–1.92 e V and observed to increase with thickness.The SEM study shows that the annealed films are uniform, fully covered and well defined. The electrical analysis shows that the conductivity is varied with film thickness and found within the order of semiconductor behavior.     

Developmental expression and cellular distribution of Mullerian inhibiting substance in the primate ovary

Ovarian follicle formation during development and follicle maturation in adulthood are crucial determinants of female fertility and disruptions in these processes may result in subfertility or infertility. Among the several factors that are involved in ovarian physiology, Müllerian inhibiting substance (MIS) also known as anti-Müllerian hormone has emerged as an important marker to predict the follicle reserve. However, the roles of MIS in human ovarian physiology are unknown. To gain an insight into the potential roles of MIS in human ovarian differentiation during development and its regulation in adulthood, the expression profiles of MIS mRNA in the developing and adult human and monkey ovaries was examined by in situ hybridization. The results revealed that in the fetal human ovaries, MIS is specifically expressed at low levels in the granulosa cells of the developing primordial follicles; a small subset (approximately 2-3%) of oocytes express high amounts of MIS. In the adult human and monkey ovary, MIS mRNA is expressed at low levels in the primordial follicles, maximally in the primary and secondary follicles, and the expression is downregulated in the antral and atetric follicles. MIS expression is extinguished in the granulosa cells only after ovulation. These observations strongly favor the regulatory roles of MIS in folliculogenesis. MIS in the primate ovary may exert its effect during the primordial follicle formation to the terminal granulosa cell differentiation. The presence of MIS in a small subset of oocytes in the fetal ovary further points towards its additional role during fetal oocyte development.