Effect of surface functional groups on hydrogen adsorption properties of Pd dispersed reduced graphene oxide

Pd/reduced graphene oxide (Pd-RGO) composites were successfully prepared from graphite and PdCl₂ precursors using wet impregnation and reverse micro emulsion methods. From hydrogen adsorption studies it is confirmed that spillover of hydrogen from Pd to graphene layers occurs at room temperature. However, at low temperatures there is negligible spillover effect and this is explained based on lower kinetic energy available with hydrogen atoms to overcome the activation barrier involved in diffusion. Detailed ¹³C MAS NMR and Raman spectroscopic studies confirmed that small amounts of structural units (functional groups) like carboxylate and polyacetylenic linkages are retained in Pd-RGO samples prepared by wet impregnation and reverse micro-emulsion methods, respectively. Such structural moieties facilitate the atomic scale mixing of Pd with the graphene layers thereby improving the spillover efficiency.     

Antiplasmodial and Antimalarial Activity of 3,5-Diarylidenetetrahydro-2H-pyran-4(3H)-ones via Inhibition of Plasmodium falciparum Pyridoxal Synthase

A series of 22 different 3,5-diarylidenetetrahydro-2H-pyran-4(3H)-ones (DATPs) were synthesized, characterized, and screened for their in vitro antiplasmodial activities against chloroquine (CQ)-sensitive Pf3D7, CQ-resistant PfINDO, and artemisinin-resistant PfMRA-1240 strains of Plasmodium falciparum. DATP 19 ( 3,5-bis(4-hydroxy-3,5-dimethoxybenzylidene)tetrahydro-2H-pyran-4(3H)-one) was found to be the most potent (IC₅₀ 1.07 μM) against PfMRA-1240, whereas 21 (3,5-bis(3,4,5-trimethoxybenzylidene)tetrahydro-2H-pyran-4(3H)-one) showed IC₅₀ values of 1.72 and 1.44 μM against Pf3D7 and PfINDO, respectively. Resistance indices (RI) as low as 0.2 to 0.5 for 10 (3,5-bis(4-nitrobenzylidene)tetrahydro-2H-pyran-4(3H)-one) and 20 (3,5-bis(3-nitrobenzylidene)tetrahydro-2H-pyran-4(3H)-one), and <1 for most other DATPs reveals their greater potency against resistant strains than the sensitive one. The single-crystal XRD data for DATP 21 are reported. In silico support was obtained through docking studies. Killing all three strains within 4–8 h, these DATPs showed rapid kill kinetics toward the trophozoite stage. Furthermore, DATP 18 (3,5-bis(quinolin-4-ylmethylene)tetrahydro-2H-pyran-4(3H)-one) inhibited PfPdx1 enzyme activity with IC₅₀ 20.34 μM, which is about twofold lower than that (IC₅₀ 43 μM) for an already known inhibitor 4PEHz. At an oral dose of 300 mg/kg body weight, DATPs 19 and 21 were found to be nontoxic to mice, and at 100 mg/kg body weight, DATP 19 was found to suppress parasitaemia, which led to an increase in median survival time by three days relative to untreated control mice in a malaria curative study.     

Information sharing and exchange in the context of product lifecycle management: Role of standards

This paper introduces a model of the information flows in Product Life cycle Management (PLM), serving as the basis for understanding the role of standards in PLM support systems. Support of PLM requires a set of complementary and interoperable standards that cover the full range of aspects of the products’ life cycle. The paper identifies a typology of standards relevant to PLM support that addresses the hierarchy of existing and evolving standards and their usage and identifies a suite of standards supporting the exchange of product, process, operations and supply chain information. A case study illustrating the use of PLM standards in a large organization is presented. The potential role of harmonization among PLM support standards is described and a proposal is made for using open standards and open source models for this important activity.     

Controlled electrodeposition of ZnO nanostructures for enhanced light scattering properties

This paper outlined how to control density and shape of electrodeposited ZnO nanorods to achieve high scattering properties. Light scattering at nanostructured metal–semiconductor interfaces is a proven method to improve absorption in photovoltaic devices. Adjustment of nanostructure shape and mean distance is critical to achieve efficient light scattering. A simple model is introduced that predicts maximal suppression of the specular transmitted light, resulting in maximal light scattering. This model predicts in an ideal case, 50 % nanostructure coverage of the electrode. Furthermore, an optimal nanostructure height has been determined depending on the incident wavelength and the refractive indices. Experimentally, the crystal density on ITO substrates was adjusted by pulsing the deposition potential, thus, removing the requirement for an additional seeding layer. The solution of the diffusion equation indicated a break-to-pulse ratio of at least 2.4 for an efficient control of the crystal density during pulsed electrodeposition. In addition, the structure height was set by varying the number of pulse cycles. Such tailored ZnO nanostructures showed a suppression of the specular transmitted light beam of 83.5 % and a diffusive forward scattering efficiency of 39 % at a wavelength of 406 nm. Thus, the optical absorption of e.g. an 80-nm thick polymeric active layer of P3HT could be increased by 47 % by applying such tailored ZnO nanostructures.     

Microbiological studies of ethnic meat products of the Eastern Himalayas

Native microorganisms from some ethnic meat products of the Eastern Himalayas such as lang kargyong, yak kargyong, faak kargyong, lang satchu, yak satchu and suka ko masu were isolated and characterized. The bacterial isolates included Lactobacillus sake, Lactobacillus curvatus, Lactobacillus divergens, Lactobacillus carnis, Lactobacillus sanfrancisco, Lactobacillus plantarum, Lactobacillus casei, Lactobacillus brevis, Enterococcus faecium, Leuconostoc mesenteroides, Pediococcus pentosaceous, Bacillus subtilis, Bacillus mycoides, Bacillus thuringiensis, Bacillus lentus and Bacillus licheniformis, Micrococcus and Staphylococcus. Yeast isolates included Debaryomyces hansenii, Debaryomyces polymorphus, Debaryomyces pseudopolymorphus, Pichia burtonii, Pichia anomala, Candida famata and the mould Rhizopus was also identified. Many of the LAB isolates demonstrated some antimicrobial activity, enzymatic activity and a few showed a high degree of hydrophobicity. None of the strains produced biogenic amines.     

Impact of bathers on levels of Cryptosporidium parvum oocysts and Giardia lamblia cysts in recreational beach waters

Recreational beach water samples collected on weekends and weekdays during 11 consecutive summer weeks were tested for potentially viable Cryptosporidium parvum oocysts and Giardia lamblia cysts using the multiplexed fluorescence in situ hybridization (FISH) method. The levels of oocysts and cysts on weekends were significantly higher than on the weekdays (P<0.01). Concentrations of oocysts in weekend samples (n=27) ranged from 2 to 42 oocysts/L (mean: 13.7 oocysts/L), and cyst concentration ranged from 0 to 33 cysts/L (mean: 9.1 cysts/L). For the samples collected on weekdays (n=33), the highest oocyst concentration was 7 oocysts/L (mean: 1.5 oocysts/L), and the highest cyst concentration was 4 cysts/L (mean: 0.6 cysts/L). The values of water turbidity were significantly higher on weekends than on weekdays, and were correlated with the number of bathers and concentration of C. parvum oocysts and G. lamblia cysts (P<0.04). The study demonstrated positive relationships between number of bathers and levels of waterborne C. parvum oocysts and G. lamblia cysts in recreational beach water. It is essential to test recreational waters for Cryptosporidium and Giardia when numbers of bathers are greatest, or limit the number of bathers in a recreational beach area.     

Comparison of defect structures in homo- and hetero-epitaxial GaP,grown using excimer laser-assisted MOVPE

Defect structures in excimer laser-assisted epitaxial GaP on (1 0 0) GaP and (1 0 0) GaAs have been examined using transmission electron microscopy (TEM). It was found that the dominant defect structures in homo-epitaxy were dislocations and stacking faults whereas the major defects in hetero-epitaxy were twins. Differential plastic deformation-induced stresses are believed to be responsible for the high density of twins in hetero-epitaxy.     

Shock-Induced Microstructures in Explosively Fabricated Superconductors

Scanning and transmission electron microscopy (including electron diffraction) have been applied to examine the consolidation, bonding, and characterization of orthorhombic, superconducting YBa₂Cu₃O₇ powder particles in explosive (shock-wave) fabricated aluminum matrix monoliths. The shock wave front (at pressures of approximately 4 GPa) roughly creates an order of magnitude greater density of microtwins and other defects in the orthorhombic structure, which is unaltered by the shock-wave compression. Some evidence for interparticle melting and rapid solidification at large interparticle voids is apparent in small, scattered amorphous regions in the dynamically consolidated superconducting powder regimes. Observations of large d.c. current carrying capacities and current densities estimated to be > 10³ A/cm² in zero applied magnetic field at 77K in practical electrical configurations suggest prospects for very high cirtical current densities resulting from strong flux pinning effects in the YBa₂Cu₃O₇ superconductor at shockwave induced defects.     

Effect of structure, particle size and relative concentration of Eu(3+) and Tb(3+) ions on the luminescence properties of Eu(3+) co-doped Y(2)O(3):Tb nanoparticles

Eu(3+) co-doped Y(2)O(3):Tb nanoparticles were prepared by the combustion method and characterized for their structural and luminescence properties as a function of annealing temperatures and relative concentration of Eu(3+) and Tb(3+) ions. For Y(2)O(3):Eu,Tb nanoparticles annealed at 600 and 1200?°C, variation in the relative intensity of excitation transitions between the (7)F(6) ground state and low spin and high spin 4f(7)5d(1) excited states of Tb(3+) is explained due to the combined effect of distortion around Y(3+)/Tb(3+) in YO(6)/TbO(6) polyhedra and the size of the nanoparticles. Increase in relative intensity of the 285?nm peak (spin-allowed transition denoted as peak B) with respect to the 310?nm peak (spin-forbidden transition denoted as peak A) with decrease of Tb(3+) concentration in the Y(2)O(3):Eu,Tb nanoparticles heated at 1200?°C is explained based on two competing effects, namely energy transfer from Tb(3+) to Eu(3+) ions and quenching among the Tb(3+) ions. Back energy transfer from Tb(3+) to Eu(3+) in these nanoparticles is found to be very poor.