53 research outputs found
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
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
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
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
PINK1 Defect Causes Mitochondrial Dysfunction, Proteasomal Deficit and α-Synuclein Aggregation in Cell Culture Models of Parkinson's Disease
Mutations in PTEN induced kinase 1 (PINK1), a mitochondrial Ser/Thr kinase, cause an autosomal recessive form of Parkinson's disease (PD), PARK6. Here, we report that PINK1 exists as a dimer in mitochondrial protein complexes that co-migrate with respiratory chain complexes in sucrose gradients. PARK6 related mutations do not affect this dimerization and its associated complexes. Using in vitro cell culture systems, we found that mutant PINK1 or PINK1 knock-down caused deficits in mitochondrial respiration and ATP synthesis. Furthermore, proteasome function is impaired with a loss of PINK1. Importantly, these deficits are accompanied by increased α-synclein aggregation. Our results indicate that it will be important to delineate the relationship between mitochondrial functional deficits, proteasome dysfunction and α-synclein aggregation
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
Studies regarding the performance of some bluegrass and ryegrass varieties used in lawns under the climatic conditions in the forrest steppe of North - East Romania
The turf varieties sold in
Romania are breeded in foreign countries
that are different in terms of climatic
conditions, and may not always perform as
well in conditions of extreme drought and
heat that often occurs in the summers of
eastern Romania. From this point of view,
trial testing of imported turf varieties in this
part of the country or another, throughout
the country, would be a necessary and
positive research especially if it would be
achieved before selling these varieties on
the romanian market, thus pleasing the
quality demands of the public and also
helping the breeders to optimize the range
of varieties for specific areas. In this
research we had the chance to test by trial,
for a period of two consecutive years, seven
varieties of kentucky bluegrass (KB) and
three of perennial ryegrass (PR) breeded in
the USA, the world market leader in
turfgrass varieties. Field trials were started
at a farm located nearby the city of Iasi, in
2005, consisting in randomized plots
replicated three times for statistical
interpretation of the data. The soil was a
chernozem soil type. Each plot had an area
of 4 m2. Seeding rate was 15g m-1 for
bluegrass varieties and 30g m-1 as
recommended by the breeding companies.
The weather conditions in the area are quite
rough for turfgrasses, with 520 mm of rain
annualy and an annual mean temperature
of 9.60C. The evaluation of turgrass overall
quality was done using the visual rating
scale used by the National Turfgrass
Evaluation Program from USA. This
organization is well accepted in more than
30 countries around the world, and the
rating scale is used by most of the turfgrass
breeders. Following results we learned that
ryegrass quality is affected by the prolonged
lack of water in a higher percentage than
bluegrass, by comparing the quality ratings
of these two varieties over a period of two
years, correlated with the climatic
conditions from the same time period. The
monthly ratings were used to calculate the
annual mean quality rating for each
individual variety, and the best quality was
observed in the year 2006, for varieties:
Nudestiny rated 6.5, Liberator rated 6.2 and Impact rated 6.1, all three belonging to Poa
pratensis species. This study proves the
importance of trial testing of imported turf
varities because of the following reasons:
there are large differences between turfgrass
species in terms of turf quality influenced
by climatic conditions but also there are
differences betwen varieties that belong to
the same botanical species, as we have seen
in the seven bluegrass varieties studied
Optimization of the production of ethyl esters by ultrasound assisted reaction of soybean oil and ethanol
Biodiesel is a renewable liquid fuel that can be produced by a transesterification reaction between a vegetable oil and an alcohol. This paper evaluates and optimizes the production of ethyl esters (biodiesel) from soybean oil and ethanol. The reaction was carried out by applying ultrasound under atmospheric pressure and ambient temperature. Response surface methodology was used to evaluate the influence of alcohol to oil molar ratio and catalyst concentration on the yield of conversion of soybean oil into ethyl esters. The process resulted in a maximum yield of 91.8% after 30 minutes of reaction. The process variables alcohol to oil ratio and catalyst to oil ratio were statistically significant regarding the yield of ethyl esters. The optimal operating condition was obtained applying an alcohol to oil molar ratio of 10.2 and a catalyst to oil weight ratio of 0.0035
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