Natural Radioactivity in Red Clay Brick Manufactured in Tlemcen-Algeria, Using Well-Shape NaI(Tl) Detector

The presence of natural radioactivity in brick and other building materials results in internal and external exposure to the general public. Therefore, it is desirable to determine the concentration of naturally occurring radionuclides. Bricks are one of the main components in building construction beside cements, granites and sand. Thus, this research has been carried out in order to investigate the levels of natural radioactivity and associated radiation hazard in Algerian red brick. The natural radioactivity due to the presence of 226Ra, 232Th and 40K in brick samples used as building materials in Tlemcen province - Algeria was measured by gamma spectrometry using NaI(Tl) scintillation well-shaped detector. In this context, brick samples were collected from two manufactories Tafna and Tounan. The mean values of activity concentrations for 226Ra, 232Th and 40K were found to be in the main value of 15.5Bq.kg-1, 11Bq.kg-1, and 196.5Bq.kg-1, respectively. The concentrations of these natural radionuclides were compared with the reported data for other countries and were found significantly lower than the world wide average (1,2). Radium equivalent activities were calculated (41.3 to 51.4) Bq.kg–1 for the analyzed samples to assess the radiation hazards arising due to the presence of these radionuclides in the samples. The calculated radium equivalent activities are lower than the limit set by the OECD report 370 Bq.kg–1 (3). The measured representative level index values for the investigated samples varied in the range (0.31 to 0.38) Bq.kg1.  External and internal hazard index (Hex,Hin), the specific dose rates in door (D) and the annual effective dose (DE) due to gamma radiation from building materials was calculated. Keywords: Brick, natural radioactivity, gamma radiation, absorbed dose, radiation exposure, Potassium, Thorium, Uranium; NaI(Tl) detector, Tlemcen

Hesperidin effects on behavior and locomotor activity of diabetic Wistar rat

Today, there are sufficient validated scientific data that support the existence of relations between diabetes and certain neuropsychiatric disorders, such as behavioral disorders, anxiety, cognitive decline and depression. The objective of this work was to investigate the effect of a natural bioflavonoid, the antioxidant hesperidin on the neuro behavioral alterations and locomotor function in streptozotocine diabetic wistar rats. Twenty eight male rats were divided equally into four groups; control, and treated series (hesperidin, streptozotocine and hesperidin+ streptozotocine) then exposed to open field test, where animals were individually placed in the center of the compartment for a period of 5 min. Results of the open field test showed high level of anxiety and a slowdown in locomotion and mental flexibility on diabetic rats. Treatment with hesperidin, significantly module these disorders of the animals related to diabetes. Thus, our results confirm the capacity of hesperidin as an antioxidant, to correct neurobehavioral and locomotion disorders related to diabetes and its complications by neutralizing free radicals generated by this metabolic disease.Key words: Diabetes, oxidative stress, hesperidin, streptozotocine

Strained quantum well photovoltaic energy converter

An indium phosphide photovoltaic cell is provided where one or more quantum wells are introduced between the conventional p-conductivity and n-conductivity indium phosphide layer. The approach allows the cell to convert the light over a wider range of wavelengths than a conventional single junction cell and in particular convert efficiently transparency losses of the indium phosphide conventional cell. The approach hence may be used to increase the cell current output. A method of fabrication of photovoltaic devices is provided where ternary InAsP and InGaAs alloys are used as well material in the quantum well region and results in an increase of the cell current output

Effect of N2* and N on GaN nanocolumns grown on Si (111) by molecular beam epitaxy

The self-induced growth of GaN nanocolumns (NCs) on SixN1−x/Si (111) is investigated as a function of the ratio of molecular to atomic nitrogen species generated via plasma assisted molecular beam epitaxy. Relative concentrations of the molecular and atomic species are calculated using optical emission spectroscopy. The growth rate (GR), diameter, and density of NCs are found to vary with the molecular to atomic nitrogen species relative abundance ratio within the plasma cavity. With increasing ratio, the GR and diameter of NCs increase while the density of NCs seems to be decreasing. The morphologies and the coalescence of GaN NCs exhibit a trend for molecular/atomic ratios up to 11, beyond which they still change but at a lower rate. The detrimental effect of taperedness of the NCs decreases with increasing molecular/atomic ratios. This is possibly because of reduction in radial growth in NCs due to increase in diffusivity of nitrogen species with increasing ratios

Influence of HiPIMS pulse widths on the deposition behaviour and properties of CuAgZr compositionally graded films

In this work, the influence of different pulse widths (25, 50 and 100 μs) during high power impulse magnetron sputtering (HiPIMS) of copper, silver and zirconium was investigated in terms of plasma properties and properties of combinatorial composition gradient CuAgZr film libraries. In situ plasma diagnostics via optical emission spectroscopy (OES), time-of-flight mass spectrometry (TOFMS), and modified quartz crystal microbalance (m-QCM), followed by film ex situ X-ray diffraction (XRD) and scanning electron microscopy (SEM) investigations allowed to determine the effect of deposition parameters on the thin films' microstructural changes. Changing the pulse width, while keeping the duty cycle constant, modified the discharge composition in the target region and the ionised fraction of the sputtered species in the substrate region. The maximum Cu ionised fraction (19 %) was found for 50 μs, resulting in compact and smooth morphology for Cu-rich films, whereas short 25 μs pulses provided porous columnar films with rough surfaces, as the result from Ar+ bombardment. For Ag-rich films, Ag segregation allowed the deposition of dense layers, regardless of the used pulse width. Furthermore, low Ag (<10 at.%) CuAgZr films produced via HiPIMS and direct-current magnetron sputtering (DCMS) were compared in terms of structural and mechanical property changes as a function of Zr contents. For the studied chemical composition range, a linear relationship between Zr content, XRD phase shift and mechanical properties was observed for HiPIMS films, in contrast to DCMS's more abrupt transitions. An increase in hardness and elastic modulus (up to 44 % and 22 %, respectively) was found for the HiPIMS films compared to DCMS ones. The obtained results highlight HiPIMS's flexibility in providing a wide range of tailoring possibilities to meet specific application requirements, such as crystalline microstructure, density and associated mechanical properties

Applying CLIPS to control of molecular beam epitaxy processing

A key element of U.S. industrial competitiveness in the 1990's will be the exploitation of advanced technologies which involve low-volume, high-profit manufacturing. The demands of such manufacture limit participation to a few major entities in the U.S. and elsewhere, and offset the lower manufacturing costs of other countries which have, for example, captured much of the consumer electronics market. One such technology is thin-film epitaxy, a technology which encompasses several techniques such as Molecular Beam Epitaxy (MBE), Chemical Beam Epitaxy (CBE), and Vapor-Phase Epitaxy (VPE). Molecular Beam Epitaxy (MBE) is a technology for creating a variety of electronic and electro-optical materials. Compared to standard microelectronic production techniques (including gaseous diffusion, ion implantation, and chemical vapor deposition), MBE is much more exact, though much slower. Although newer than the standard technologies, MBE is the technology of choice for fabrication of ultraprecise materials for cutting-edge microelectronic devices and for research into the properties of new materials