The Productivity and Quality of Alfalfa (Medicago sativa L.) in Romanian Forest Steppe

Alternative use of alfalfa, for various purposes, including the production of biofuels or food supplement for human alimentation, is a study topic still in its early stages of research. Studying and understanding the biology of alfalfa and the factors with a major influence on it are very important activities. The productivity and quality of alfalfa are two indicators that help determine, in addition to economic value, the way in which alfalfa can be used. Evolution of alfalfa yield and quality depends on many factors, such as the growth stage of alfalfa plants at harvesting. It was observed over three years of vegetation the influence of alfalfa plant growth stage at harvest on plant height, leaves/stems ratio, production of leaves, stems and whole plant (DM - dry matter) per hectare and on quality indicators (CP - crude protein, NDF - neutral detergent fiber and ADF - acid detergent fiber). The results showed that, with the advancement of phenological phases, from early bud stage to complete flowering, the total biomass output raised from 2.79 Mg·ha-1 to 4.60 Mg·ha-1, the neutral detergent fiber raised from 48.4-50.6% to 62.0-67.7%, while crude protein content decreased from 21.2-24.0% to 13.3-16.5%. The parameter values were correlated with alfalfa growth stage during the harvesting (significant at the 0.05 and 0.01 probability levels)

Optical control of spin coherence in singly charged (In,Ga)As/GaAs quantum dots

Electron spin coherence has been generated optically in n-type modulation doped (In,Ga)As/GaAs quantum dots (QDs) which contain on average a single electron per dot. The coherence arises from resonant excitation of the QDs by circularly-polarized laser pulses, creating a coherent superposition of an electron and a trion state. Time dependent Faraday rotation is used to probe the spin precession of the optically oriented electrons about a transverse magnetic field. Spin coherence generation can be controlled by pulse intensity, being most efficient for (2n+1)pi-pulses.Comment: 5 pages, 4 figure

Temperature dependence of capture coefficients in trapping phenomena

The temperature dependence of the capture coefficients in trapping phenomena is investigated. It is proved that, besides the dependence induced by the thermal velocity of the carriers, the stress-induced traps at the interfaces of the multi-layered structures present a supplementary temperature dependence. This dependence is found to be of Gaussian type and is in a good agreement with the experimental results. © 2010 IEEE

Stress-induced traps in multilayered structures

The trap parameters of defects in Si/CaF 2 multilayered structures were determined from the analysis of optical charging spectroscopy measurements. Two kinds of maxima were observed. Some of them were rather broad, corresponding to "normal" traps, while the others, very sharp, were attributed to stress-induced traps. A procedure of optimal linear smoothing the noisy experimental data has been developed and applied. This procedure is based on finding the minimal value of the relative error with respect to the value of the smoothing window. In order to obtain a better accuracy for the description of the trapping-detrapping process, a Gaussian temperature dependence of the capture cross-sections characterizing the stress-induced traps was introduced. Both the normal and the stress-induced traps have been characterized, including some previously considered as only noise features. ©2011 American Institute of Physics

Heterostructures based on small molecules organic compounds

Heterostructures with layers from small molecules organic compounds were deposited on ITO/glass substrate by thermal vacuum evaporation (TVE) technique. Structural, optical and morphological investigations were carried out on the realisedlayers (zinc phthalocyanine - ZnPc, fullerene - C60 and 1,4,5,8-naphthalene - tetracarboxylic dianhydride - NTCDA). The films are polycrystalline keeping the morphological features characteristic to these materials. The prepared hetero structures reveal a large absorption domain in the visible domain. The current-voltage (I-V) characteristics of the investigated structures, recorded in dark, present an improvement in the current value (~one order of magnitude) for the standard structure (ITO/PEDOT:PSS/ZnPc/C60/NTCDA/Al) with a supplimentary layer of poly(3,4 ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). For the inverted structure (Al/NTCD/C60/ZnPc/ITO) was also noticed an increased curent value in comparasion with that observed for the standard structure

Investigations on the properties of a two-dimensional nanopatterned metallic film

This paper presents some investigations of the effect of nanopatterning on the properties of aluminum layer deposited by sputtering. UV-Nanoimprint Lithography technique has been used for the realization of a 2D array of nanostructures (pillars) in aluminum film characterized by cylindrical shape and the following structural parameters: diameter between 400 nm and 490 nm, depth between 320 nm and 420 nm and periodicity of 1.1 μ m, which have been revealed by SEM and AFM measurements. The UV-Vis transmission, reflection and photoluminescence measurements have evidenced the effect of the nanopatterning on the optical properties of the Al layer

Flexible heterostructures based on metal phthalocyanines thin films obtained by MAPLE

Heterostructures based on zinc phthalocyanine (ZnPc), magnesium phthalocyanine (MgPc) and 5,10,15,20-tetra(4-pyrydil)21H,23H-porphine (TPyP) were deposited on ITO flexible substrates by Matrix Assisted Pulsed Laser Evaporation (MAPLE) technique. Organic heterostructures containing (TPyP/ZnPc(MgPc)) stacked or (ZnPc(MgPc):TPyP) mixed layers were characterized by X-ray diffraction-XRD, photoluminescence-PL, UV–vis and FTIR spectroscopy. No chemical decomposition of the initial materials was observed. The investigated structures present a large spectral absorption in the visible range making them suitable for organic photovoltaics applications (OPV). Scanning electron microscopy-SEM and atomic force microscopy-AFM revealed morphologies typical for the films prepared by MAPLE. The current–voltage characteristics of the investigated structures, measured in dark and under light, present an improvement in the current value (∼3 order of magnitude larger) for the structure based on the mixed layer (Al/MgPc:TPyP/ITO) in comparison with the stacked layer (Al/MgPc//TPyP/ITO). A photogeneration process was evidenced in the case of structures Al/ZnPc:TPyP/ITO with mixed layers

A review of combined advanced oxidation technologies for the removal of organic pollutants from water

Water pollution through natural and anthropogenic activities has become a global problem causing short-and long-term impact on human and ecosystems. Substantial quantity of individual or mixtures of organic pollutants enter the surface water via point and nonpoint sources and thus affect the quality of freshwater. These pollutants are known to be toxic and difficult to remove by mere biological treatment. To date, most researches on the removal of organic pollutants from wastewater were based on the exploitation of individual treatment process. This single-treatment technology has inherent challenges and shortcomings with respect to efficiency and economics. Thus, application of two advanced treatment technologies characterized with high efficiency with respect to removal of primary and disinfection by-products in wastewater is desirable. This review article focuses on the application of integrated technologies such as electrohydraulic discharge with heterogeneous photocatalysts or sonophotocatalysis to remove target pollutants. The information gathered from more than 100 published articles, mostly laboratories studies, shows that process integration effectively remove and degrade recalcitrant toxic contaminants in wastewater better than single-technology processing. This review recommends an improvement on this technology (integrated electrohydraulic discharge with heterogeneous photocatalysts) viz-a-vis cost reduction in order to make it accessible and available in the rural and semi-urban settlement. Further recommendation includes development of an economic model to establish the cost implications of the combined technology. Proper monitoring, enforcement of the existing environmental regulations, and upgrading of current wastewater treatment plants with additional treatment steps such as photocatalysis and ozonation will greatly assist in the removal of environmental toxicants