Formation of Heteroepitaxy in Different Shapes of Au–CdSe Metal–Semiconductor Hybrid Nanostructures

Formation of heteroepitaxy and designing different‐shaped heterostructured nanomaterials of metal and semiconductor in solution remains a frontier area of research. However, it is evident that the synthesis of such materials is not straightforward and needs a selective approach to retain both metal and semiconductor identities in the reaction system during heterostructure formation. Herein, the epitaxial growth of semiconductor CdSe on selected facets of metal Au seeds is reported and different shapes (flower, tetrapod, and core/shell) hetero‐nanostructures are designed. These results are achieved by controlling the reaction parameters, and by changing the sequence and timing for introduction of different reactant precursors. Direct evidence of the formation of heteroepitaxy between {111} facets of Au and (0001) of wurtzite CdSe is observed during the formation of these three heterostructures. The mechanism of the evolution of these hetero‐nanostructures and formation of their heteroepitaxy with the planes having minimum lattice mismatch are also discussed. This shape‐control growth mechanism in hetero‐nanostructures should be helpful to provide more information for establishing the fundamental study of heteroepitaxial growth for designing new nanomaterials. Such metal–semiconductor nanostructures may have great potential for nonlinear optical properties, in photovoltaic devices, and as chemical sensors.     

Pseudo-Dynamic Testing for Seismic Performance Assessment of Buildings with Seismic Isolation System Using Scrap Tire Rubber Pad Isolators

Investigation of seismic performance of buildings with STRP （scrap tire rubber pad） seismic isolators by means of pseudo-dynamic tests and numerical simulation is presented. The isolated building is numerically modeled, while the base isolation layer is considered as the experimental substructure in the pseudo-dynamic tests. The test result verifies that the STRP isolator shows acceptable shear deformation performance predicted by the design methods, and demonstrated that seismic isolation using STRP works as a protective measure to provide enhanced seismic performance of the building indicated by the reduction of top floor absolute acceleration, drift and base shear as designated.     

Natural occurrence of aflatoxin B1 in sorghum grown in different geographical regions of India

BACKGROUND: Sorghum (Sorghum bicolor (L.) Moench) is an important coarse cereal crop grown for grain and fodder in the semi‐arid Tropics, mainly in Asian and African countries. In India sorghum is consumed as human food and poultry feed. Sorghum grain grown in the rainy season (kharif) is becoming severely affected by grain moulds, the major fungi involved being Aspergillus, Fusarium and Curvularia. If the extent of mould is severe, the grain is unsafe for consumption owing to contamination by mycotoxins. RESULTS: This paper presents a multi‐centre study conducted in sorghum to evaluate natural contamination of aflatoxin B₁ in India. A total of 1606 grain sorghum samples were collected during the rainy (kharif) season across 4 years from seven states of India, representing different geographical regions of the country. Aflatoxin B₁ contamination during 2007–08 was the highest (13.1%), followed by samples from the year 2004–05 (2.85%). The samples collected in years 2005–06 and 2006–07 showed contamination below 1%. The number of samples (35) showing aflatoxin B₁ contamination above the safety limit was also highest during 2007–08 as compared to samples from the other years. CONCLUSION: This study, conducted for 4 years, showed that natural contamination of aflatoxin B₁ in sorghum grown in India is within safety limits (20 µg kg^?1) recommended by the Codex Alimentarius Committee and 73% of samples were positive for toxin. However, 0.75% (12) of total samples contained aflatoxin above the safety limit. The overall occurrence of toxin from Madhya Pradesh and Rajasthan was below 5 µg kg^?1. Copyright © 2012 Society of Chemical Industry     

Effect of black tea (Camellia sinensis) on virulence traits of clinical isolates of Shigella dysenteriae and Escherichia coli EPEC P2 1265 strain

The crude tea polyphenols of regular black tea were investigated in vitro for effect on virulence traits of Shigella dysenteriae and Enteropathogenic Escherichia coli (EPEC P₂ 1265) strains. Results showed that crude tea polyphenols of black tea significantly increased (p < 0.05) phagocytic uptake of tea-adapted S. dysenteriae cells in 30 min by 37.68% and phagocytic killing by ten-folds in 3 h. Further, acid tolerance response in EPEC P₂ 1265 strain was also decreased in tea-adapted culture in order: Acid adapted, tea un-adapted > acid un-adapted, tea un-adapted > acid adapted, tea adapted > acid un-adapted, tea-adapted. These results inferred that polyphenolic treatment of bacterial culture disrupts pH hemostasis which caused complete bacterial killing in 120 min when compared to tea-untreated culture where complete killing required 180 min. Serum bactericidal activity was also increased in tea-treated culture of EPEC P₂ 1265 when 2-h serum treatment caused complete bacterial killing but un-treated cells were killed after 3 h. Also, significant increase (p < 0.05) in enterochelin production was observed when EPEC P₂ 1265 was grown in presence of tea. The present findings indicate that boiling water black tea extract reduces expression of virulence traits by S. dysenteriae and E. coli EPEC P₂ 1265 enteropathogen as shown by decreased bacterial survival strategies. The results promote the use of tea extract against multidrug resistant Mycobacterium tuberculosae (MDR-TB) strains and other enteropathogens.     

Inverse emulsion polymerization-assisted designing of superparamagnetic poly (2-hydroxyethyl methacrylate) nanoparticles and magnetically triggered release of cisplatin

Superparamagnetic nanocarriers of poly (2-hydroxyethyl methacrylate) (PHEMA) were prepared by carrying out benzoyl peroxide (BPO) initiated inverse emulsion-free radical polymerization of HEMA in the presence of poly (vinyl alcohol) (PVA) and subsequent in situ precipitation of magnetite within the PHEMA matrix. The as-prepared nanoparticles were characterized by FTIR and UV–visible spectroscopy, vibrating sample magnetometry (VSM), particle size and zeta potential analysis, and transmission electron microscopy, respectively. The PHEMA nanocarriers were investigated for their blood compatibility, and cytotoxicity response to L929 cells. The superparamagnetic nanoparticles were loaded with an anticancer drug cisplatin and the release profiles of the drug were examined as a function of various experimental parameters like composition of the PHEMA nanocarriers, percentage of drug loading, and strength of the externally imposed magnetic field. The kinetics of the drug release process was also investigated, and the obtained release data were applied to different mathematical kinetic models to explore the nature of the release mechanism.     

Performance analysis of gas sensing device and corresponding IoT framework in mines

Microsystem Technologies - Gas sensor devices usage have found prominence in fields like artificial olfactory systems and is often used to keep in check pollution and other toxic gas hazards....