Experimental investigation of particle migration in suspension flow through bifurcating microchannels

Experimental measurements of velocity and concentration profiles were carried out to study transport of non‐colloidal suspension in bifurcating micro channels for both diverging and converging flow conditions using a combination of mirco‐particle image velocimetry and particle tracking velocimetry techniques. Migration of particles across the streamline was observed and symmetric velocity and concentration profile in the inlet branch becomes asymmetric in the daughter branches. Further migration of particles toward the center of the channel in the outlet branch make the profiles again symmetric. The evolution of velocity and concentration profiles was observed to be different in the symmetric and asymmetric bifurcation channels. The comparison of the streamlines for the fluid and the particles showed significant deviation near the bifurcation region. This may explain why there is unequal flow and particle partitioning during flow of suspension in asymmetric bifurcating channels as reported in many previous studies. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2293–2307, 2018     

Verification of some building materials as gamma-ray shields

The shielding properties for gamma rays of a few low Z materials were investigated. The values of the mass attenuation coefficient, equivalent atomic number, effective atomic number, exposure buildup factor and energy absorption buildup factor were calculated and used to estimate the shielding effectiveness of the samples under investigation. It has been observed that the shielding effectiveness of a sample is directly related to its effective atomic number. The shielding character of any sample is a function of the incident photon energy. Good shielding behaviour has been verified in soil samples in the photon energy region of 0.015-0.30 MeV and of dolomite in 3-15 MeV. The results have been shown graphically with more useful conclusions.     

Colorimetric detection of nucleic acid signature of shiga toxin producing Escherichia coli using gold nanoparticles

Enterohemorrhagic E. coil (EHEC) serotype O157:H7 is one of the major pathogens, responsible for the severe disease outbreaks. EHEC causes diseases in humans through production of shiga-like toxin leading to bloody diarrhea. The toxin is encoded by stx2 gene in E. coli. The current methodology for detection of EHEC relies on fluorogenic-substrate based culture media or nucleic acid amplification based Real-Time Polymerase Chain Reaction assays that are either time consuming or need expensive instrumentation. In this study, the optical properties of gold nanoparticles (GNPs) have been exploited for detection of nucleic acid of Escherichia coli O157:H7. The stx2 gene representing EHEC signature has been targeted using the gold nanoparticle probes. Gold nanoparticles (GNPs) of 20 +/- 0.2 nm were synthesised by citrate reduction method and characterised by spectroscopy and transmission electron microscopy. The GNPs were functionalised with 19 and 22 bp of thiolated single stranded DNA complementary to target highly conserved 149 bp region of stx2 gene. Transmission Electron Microscopy revealed the hybridization, aggregation and reduction in the interparticle distances of the GNP probes in the presence of target DNA. The aggregation and the spectral shift in the plasmon band observed with 10(6) copies of target DNA indicates feasibility of a simple and quick colorimetric 'spot and read' test in contrast to amplification based detection methods.     

Impact of Gd Doping on Morphology and Superconductivity of NbN Sputtered Thin Films

We report the effect of Gd inclusion in the NbN superconductor thin films. The films are deposited on single crystalline Silicon (100) by DC reactive sputtering technique, i.e., deposition of Nb and Gd in presence of reactive N₂ gas. The fabricated relatively thick films (400 nm) are crystallized in cubic structure. These films are characterized for their morphology, elemental analysis, and roughness by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDAX), and Atomic Force Microscopy (AFM) respectively. The optimized film (maximum T _c ) is achieved with gas ratio of Ar:N₂ (80:20) for both pristine and Gd-doped films. The optimized NbN film possesses T _c (R=0) in zero and 140 kOe fields are at 14.8 K and 8.8 K, respectively. The Gd-doped NbN film showed T _c (R=0) in zero and 130 kOe fields at 11.2 K and 6.8 K, respectively. The upper critical field H _c2(0) of the studied superconducting films is calculated from the magneto-transport [R(T)H] measurements using GL equations. It is found that Gd doping deteriorated the superconducting performance of NbN.     

A Numerical Method for Multiphase Incompressible Thermal Flows with Solid–Liquid and Liquid–Vapor Phase Transformations

ABSTRACT

A numerical method for multiphase incompressible thermal flows with solid–liquid and liquid–vapor phase transformations is presented. The flow is mainly driven by thermocapillary force and vaporization. Based on the level set method and mixture continuum model, a set of governing equations valid for solid, liquid, and vapor phases is derived, considering phase boundary conditions as source terms in the transport equations. The vaporization process is treated as a source term in the continuity equation. The model developed is applied to the laser welding process, where the flow is coupled with optical phenomena. Formation and collapse of a laser-created hole is simulated.     

Covulcanization of LLDPE/EMA blends using dicumyl peroxide

The effect of dicumyl peroxide (DCP) content on the gel fraction, mechanical, dynamic mechanical, and thermal properties of linear low‐density polyethylene (LLDPE)/ethylene‐co‐methyl acrylate (EMA) blends were studied. Gel content of the blends increases with increasing DCP content, and EMA is more prone to crosslinking than LLDPE. Wide‐angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC) were used to study the effect of DCP crosslinking on percent crystallinity and crystalline structure of the blends and individual components. At lower level of DCP loading, crosslinking process does not have significant effect on the crystalline structure of the LLDPE, which was confirmed from the percent crystallinity and lattice distance value. However, at higher DCP content, percent crystallinity decreases significantly. At lower EMA concentration (<50%), percent crystallinity and lattice distance remain unchanged up to 2 wt % of DCP. For EMA contents of more than 50 wt %, increasing DCP content reduces the crystallinity of the blends and increases the lattice distance. The highest level of mechanical and dynamic mechanical properties was observed for 60/40 LLDPE/EMA blends at 2 wt % DCP. Addition of LLDPE‐g‐MA (3 wt %) as a compatibilizer enhances the properties of the vulcanizates. Blends crosslinked with DCP up to 0.3 wt % can easily be reprocessed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Epoxy—Polyester IPNs modified with aromatic amines

Semi-interpenetrating polymer networks (Semi-IPNs) based on epoxy and unsaturated polyester resin (UPR; added in 5.9 and 11.1 wt %) have been prepared by chemical route. Room temperature curing was attempted using triethylene tetramine as a hardener. Blend with 11.1% UPR is found to exhibit best mechanical properties. Further, blends were also prepared by adding aromatic amines such as diphenylamine (DPA, secondary amine) and benzidine (Bz, primary amine). Structural elucidation of the samples through identification of functional groups was carried out with the help of Fourier transform infra red spectroscopy. Absence of peak at 915 cm⁻¹ (characteristic of epoxy ring) confirmed complete curing in all the blends. The mechanical properties such as hardness, izod impact and tensile strength of blends were compared. The co-cured blends show decrease in shore hardness (≈ 1–6%), while, the izod impact exhibits an opposite trend. Blends with 10% DPA and Bz show an increase in izod impact by 268.6% and 38.8% respectively. Further, the tensile strength is observed to be enhanced by 45% in case of DPA while addition of Bz reduces it by 32.8%. Thermal properties were studied by thermogravimetric (TGA) and differential scanning calorimetric (DSC) analysis. TGA shows no significant change in onset and decomposition temperature but temperature at which it melts is lowered almost by 100–150°C together with the onset temperature (by ≈ 200°C) observed in DSC. Scanning electron micrographs reveal granular nature of the samples. The homogeneity of blends appears to be good. The blends co-cured with DPA are relatively crystalline compared with others. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Sensory evaluation of black pigmented rice (Oryza sativa cv. Poireton) wine fortified with probiotic Lactobacillus acidophilus ATCC 4356 and Lactobacillus sakei ATCC 15521 using fuzzy logic

Rice wine was prepared in the laboratory from a black pigmented rice (cv. Poireton) using standardized methodology. The wine was fortified with the probiotic strains Lactobacillus acidophilus ATCC 4356 and Lactobacillus sakei ATCC 15521 and allowed to undergo a storage period of 28 days at 4°C. These rice wines were compared with a commercial wine used as a standard reference wine. A panel consisting of 30 judges performed the sensory evaluation. The scores obtained were based on the quality attributes of colour, taste, aroma and alcoholic strength. Analysis of the sensory scores and ranking of the different samples were performed using fuzzy analysis. The quality attributes were also ranked according to their importance in the overall acceptability. Colour and alcoholic strength were accorded the highest importance, compared with aroma and taste, as quality attributes. The rice wines were rated as ‘not satisfactory’, ‘fair’, ‘medium’, ‘good’ and ‘excellent’ on the sensory scale. Out of the wines prepared, black pigmented rice wine fortified with L. acidophilus was the most acceptable and was ranked as ‘good’, which was also at par with the commercial wine. On the other hand, black pigmented rice wine fortified with L. sakei and black pigmented rice wine fortified with L. acidophilus and L. sakei were ranked in the ‘satisfactory’ category followed by the unfortified wine ranked in the ‘fair’ category. Copyright © 2015 The Institute of Brewing & Distilling     

Analysis of free and bound aroma compounds of pomegranate (Punica granatum L.)

Volatile aroma compounds were isolated from pomegranate arils by high vacuum distillation (HVD) and solvent extraction with diethyl ether. The HVD distillate exhibited a fresh-fruity and characteristic pomegranate aroma while the total ether extract was devoid of this note in its concentrate. Gas chromatography–mass spectroscopy (GC–MS) analysis revealed the presence of 3-octen-1-yl acetate, trans-3-hexen-1-ol, hexanol and 2-methyl pentanol only in the high vacuum distillate. Ether extract was dominated by 2-heptanol, 2-nonanol and 3-methyl-2-butanol. Based on olfactometric analysis of the HVD isolate, 3-octen-1-yl acetate was identified as the key odorant of pomegranate. Chemical synthesis of this compound, further confirmed its structure. Among the bound aroma compounds, 2-phenylethanol (40%), alpha-terpineol (4.53%) and 2-heptanol (6.35%) were identified as the major compounds existing as glycoconjugates. Identification of the character impact compound and the occurrence of glycosidic precursors in pomegranate are being reported here for the first time.