Development of a simple low-cost solar simulator for indoor collector testing

Indoor test methods for solar collectors are widely accepted and recommended by ASHRAE. The development of a solar simulator for indoor testing and the certification procedure for photo-thermal solar devices is discussed in this paper. The system consists of 14 quartz halogen lamps and provides a testing area of about 1 × 1 m. The irradiance can be varied from 400 to 1500 W/m². This is achieved by varying the input power supplied to individual lamps. The radiation output characteristics of a single lamp have been studied. The distribution of intensity over the covered area of 1·20 × 1·20 m has been recorded using a precision Eppley pyranometer.A variety of collectors—evacuated tubular collectors and flat-plate collectors of both liquid and air heating types—has been tested under sufficiently stable insolation conditions. Results for a conventional solar air heater are presented together with suggestions for further improvements.     

Tripodal amido complexes: molecular "claws" in main group and transition metal chemistry

The chemistry of transition metal amides has received new impetus in recent years due to the systematic exploitation of the amido function [NR(2)](-) in ligand design. A class of 3-fold symmetrical tripodal amido ligands has proved to be a valuable tool in the stabilization of early transition metal and main group metal complexes and complex fragments. Moreover, promising strategies for their use as chemical reagents and homogeneous catalysts have been developed. An overwiew of the current state of this field is given and the potential for further development will be highlighted.     

Crystal structure,phonon modes,and bond characteristics of AgPb2B2V3O12 (B = Mg,Zn) microwave ceramics

AgPb₂B₂V₃O₁₂ (B = Mg, Zn) ceramics with low sintering temperature were synthesized via the conventional solid-state reaction route. Rietveld refinements of the X-ray diffraction patterns confirm cubic symmetry with space group . The number of observed vibrational modes and those predicted by group theoretical calculations also confirm the space group. At the optimum sintering temperature of 750°C/4 hours, AgPb₂Mg₂V₃O₁₂ has a relative permittivity of 23.3 ± 0.2, unloaded quality factor () of 26 900 ± 500 GHz (), and temperature coefficient of resonant frequency of 19.3 ± 1 ppm/°C, while AgPb₂Zn₂V₃O₁₂ has the corresponding values of 26.4 ± 0.2, 28 400 ± 500 GHz () and –18.4 ± 1 ppm/°C at 590°C/4 hours. Microwave dielectric properties of a few reported garnets and Pb₂AgB₂V₃O₁₂ (B = Mg, Zn) ceramics were correlated with their intrinsic characteristics such as the Raman shifts as well as width of A_1g Raman bands. Higher quality factor was obtained for lower full width at half-maxima (FWHMs) values of A_1g modes. The increase in B-site bond valence contributes to high and low |τ_f| with the substitution of Zn²⁺ by Mg²⁺. Furthermore, the high ionic polarizability and unit cell volume with Zn²⁺substitution contribute to increased relative permittivity.     

Design and analysis of RF MEMS shunt switch for V-band applications

Microsystem Technologies - In this paper, we have designed and simulations of RF MEMS shunt switch. The electro-mechanical and electromagnetic analysis of the switch have been done using COMSOL...     

Biosynthesis of zinc oxide nanoparticles by petals extract of Rosa indica L., its formulation as nail paint and evaluation of antifungal activity against fungi causing onychomycosis

Aim: The authors report the biological synthesis of zinc oxide nanoparticles (ZnO‐NPs) from the petals extract of Rosa indica L. (rose). Its efficacy was evaluated against two dermatophytes: namely: Trichophyton mentagrophytes and Microsporum canis which cause onychomycosis. The activity of antibiotics against the tested dermatophytes was enhanced, when evaluated in combination with ZnO‐NPs. Methods and results: The synthesised ZnO‐NPs were preliminary detected by using ultraviolet UV visible spectroscopy, which showed specific absorbance. The ZnO‐NPs were further characterised by nanoparticle tracking analysis (NTA), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X‐ray diffraction and Zetasizer. Moreover, nanoparticles containing nail paint (nanopaint) was formulated and its antifungal activity was also assessed against T. mentagrophytes and M. canis. ZnO‐NPs and formulated nanopaint containing ZnO‐NPs, both showed significant antifungal activity. The maximum activity was noted against M. canis and lesser against T. mentagrophytes. Minimum inhibitory concentration of ZnO‐NPs was also determined against the dermatophytes causing onychomycosis infection. Conclusion: ZnO‐NPs can be utilised as a potential antifungal agent for the treatment of onychomycosis after more experimental trials.Inspec keywords: diseases, zinc compounds, nanoparticles, nanofabrication, antibacterial activity, microorganisms, nanomedicine, ultraviolet spectra, visible spectra, Fourier transform infrared spectra, transmission electron microscopy, X‐ray diffraction, biomedical materials, patient treatmentOther keywords: zinc oxide nanoparticle biosynthesis, Rosa indica L petals extract, nail paint, antifungal activity evaluation, dermatophyte, Trichophyton mentagrophytes, Microsporum canis, antibiotics activity, ultraviolet‐visible spectroscopy, nanoparticle tracking analysis, Fourier transform infrared spectroscopy, transmission electron microscopy, X‐ray diffraction, zetasizer, antifungal agent, onychomycosis treatment     

Biogenic copper nanoparticles promote the growth of pigeon pea (Cajanus cajan L.)

Environmental pollution and toxicity have been increasing due to the overuse of chemical fertilisers, which has encouraged nanotechnologists to develop eco‐friendly nano‐biofertilisers. The authors demonstrated the effect of biogenic copper nanoparticles (CuNPs) on the growth of pigeon pea (Cajanus cajan L.). The UV–visible analysis showed absorbance at 615 nm. Nanoparticle tracking and analysis revealed particle concentration of 2.18 × 10⁸ particles/ml, with an average size of 33 nm. Zeta potential was found to be −16.7 mV, which showed stability. X‐ray diffraction pattern depicted the face centred cubic structure of CuNPs; Fourier transform infrared spectroscopy demonstrated the capping due to acidic groups, and transmission electron micrograph showed nanoparticles with size 20–30 nm. The effect of CuNPs (20 ppm) on plant growth was studied, for the absorption of CuNPs by plants on photosynthesis, which was evaluated by measuring chlorophyll a fluorescence using Handy‐Plant Efficiency Analyser. CuNPs treatment showed a remarkable increase in height, root length, fresh and dry weights and performance index of seedlings. The overall growth of plants treated with CuNPs after 4 weeks was recorded. The results revealed that inoculation of CuNPs contribute growth and development of pigeon pea due to growth promoting activity of CuNPs.Inspec keywords: pollution, toxicology, nanotechnology, cropsOther keywords: biogenic copper nanoparticles, pigeon pea, Cajanus cajan L, environmental pollution, toxicity, chemical fertilisers, nanotechnologists, eco‐friendly nano‐biofertilisers, cash crop, UV‐visible analysis, nanoparticle tracking, zeta potential, X‐ray diffraction pattern, Fourier transform infrared spectroscopy, acidic groups, transmission electron micrograph, photosynthesis, chlorophyll, fluorescence, Handy‐Plant Efficiency Analyser, performance index     

Ascorbic acid imprinted polymer-modified graphite electrode: A diagnostic sensor for hypovitaminosis C at ultra trace ascorbic acid level

A new kind of molecularly imprinted polymer-modified graphite electrode was fabricated by “grafting-to” approach, incorporating sol–gel technique, for the detection of acute deficiency in serum ascorbic acid level (SAAL), manifesting hypovitaminosis C. The modified electrode exhibited ascorbic acid (AA) oxidation at less positive potential (0.0 V) than the earlier reported methods, resulting in a limit of detection as low as 6.13 ng mL⁻¹ (RSD = 1.2%, S/N = 3). The diffusion coefficient (1.096 × 10⁻⁵ cm² s⁻¹), rate constant (7.308 s⁻¹), and Gibb's free energy change (−12.59 kJ mol⁻¹) due to analyte adsorption, were also calculated to explore the kinetics of AA oxidation. The proposed sensor was found to enhance sensitivity substantially so as to detect ultra trace level of AA in the presence of other biologically important compounds (dopamine, uric acid, etc.), without any cross interference and matrix complications from biological fluids and pharmaceutical samples.     

Improved statistics of sub-mesoscale eddies in the Baltic Sea retrieved from SAR imagery

In the present article the spatio-temporal distribution of sub-mesoscale eddies seen in Envisat Advanced Synthetic Aperture Radar (ASAR) imagery of the Baltic Sea is discussed. A total of 1250 ASAR images acquired between 2009 and 2011 form the basis of our studies and show imprints of almost 7000 sub-mesoscale eddies. Since the visibility of vortical structures in synthetic aperture radar (SAR) imagery significantly depends on the near-surface wind speed, wind data from a numerical model of the Baltic Sea were additionally used to obtain improved eddy statistics. Seasonally averaged fields of near-surface wind speed, surface currents, sea surface temperature (SST), and SST gradient were also analysed in order to reveal the role of these hydrophysical parameters in the observed spatial and temporal variation of sub-mesoscale eddies.     

Control of Variation by Reward Probability.

Two bar-press experiments with rats tested the rule that reducing expectation of reward increases the variation from which reward selects. Experiment 1 used a discrete-trial random-interval schedule, with trials signaled by light or sound. One signal always ended with reward; the other signal ended with reward less often. The 2 signals were randomly mixed. Bar-press duration (how long the bar was held down) varied more during the signal with the lower probability of reward. Experiment 2 closely resembled Experiment 1 but used a random-ratio schedule rather than a random-interval schedule. Again, bar-press duration varied more during the signal with the lower probability of reward. The results support the rule--the first well-controlled comparisons to do so. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clean seas: a North Sea test site

The Clean Seas project focused on the role that existing Earth observing satellites might play in monitoring marine pollution. Results are presented here from August 1997, for the North Sea test site, using sea surface temperature (SST), colour and synthetic aperture radar (SAR) images in conjunction with a hydrodynamic model. There was good correlation between data sources, e.g. between SST and ERS-2 SAR images. Both datasets showed the development of fine plume structures close to the Rhine outflow, apparently associated with the outflow, and possibly caused by tidal pulsing of the Rhine Plume.

The model reproduced general temperature and sediment distributions well, but fine structures were not reproduced. Model sediment distribution patterns were verified using ‘chlorophyll concentration’ data from colour sensors, representative of sediment concentration in turbid water. In conjunction with the visible channels of the Advanced Very High Resolution Radiometer and Along-Track Scanning Radiometer, they give an uncalibrated measure of the sediment load. The model gives a more complete picture of the temporal dispersion of the Rhine Plume over time than is evident from the remotely sensed data alone.