Structural,optical and electrical properties of CuSCN nano-powders doped with Li for optoelectronic applications

Pure and Li-doped CuSCN nano-powders were prepared using an in situ method. Structural, optical and electrical properties of the prepared samples were investigated using X-ray diffraction (XRD), UV–Visible spectrophotometer and simple electrical circuit. XRD measurements showed that all pure and doped samples with 1%–7% Li have the hexagonal structures. The crystallite size of CuSCN decreased from 39.46 nm to 36.42 nm with increasing Li concentration from 0 to 7%. The values of direct and indirect optical band gap energies of pure and Li-doped CuSCN nano-powders were calculated. Direct optical band gap energy increased from 3.60 eV to 4.20 eV and indirect optical band gap energy increased from 2.36 eV to 3.20 eV by doping CuSCN with Li. The dc electrical conductivity was calculated at room temperature for all prepared CuSCN samples. Electrical conductivity decreased from 6.04 × 10⁻⁸ (Ω.cm)⁻¹ to 2.82 × 10⁻⁸ (Ω.cm)⁻¹ with increasing Li concentration from 0 to 7%. The optoelectronic performance of CuSCN was improved by doping with Li. As a result, Li-doped CuSCN could be a good candidate material as a window layer and as a hole transport layer (HTL) for producing more efficient solar cells.     

DC Electrical Conductivity of the Direct Electrochemically Synthesized Polythiophene Metal Complexes

Electrochemical anodic oxidation of a metal anode in an acetone solution of 2,5-diamino-3,4-dicyanothiophene gave the polythiophene metal complexes of Co, Ni, Cu, Zn, Cd, and Sn. Chemical analyses, as well as FTIR and electronic spectral data, are presented to confirm the formulation of the isolated materials. DC electrical conductivity measurements of the polymer complexes were measured in the range 300–500 K in the annealed and 5% doped forms. The products gave electrical conductivity in the semi-conducting region that increased by heat.     

Medical dosimetry in Hungary

Radiation exposure of medical staff during cardiological and radiological procedures was investigated. The exposure of medical staff is directly connected to patient exposure. The aim of this study was to determine the distribution of doses on uncovered part of body of medical staff using LiF thermoluminescent (TL) dosimeters in seven locations.Individual Kodak film dosimeters (as authorized dosimetry system) were used for the assessment of medical staff's effective dose. Results achieved on dose distribution measurements confirm that wearing only one film badge under the lead apron does not provide enough information on the personal dose.The value of estimated annual doses on eye lens and extremities (fingers) were in good correlation with international publications.     

Preconcentration of trace nickel lons from aqueous solutions by using a new and low cost chelating polystyrene adsorbent

A simple and reliable method has been developed using chelating polymeric adsorbent (PSAHSB) to preconcentration of trace amount of Ni(II) ions from aqueous solutions under static loading conditions, and their determination by Ultraviolet and visible (UV–Vis) absorption spectroscopy. The influences of some analytical adsorption parameters, such as pH, temperature and contact time, the ionization constants of chelating groups in the adsorbent and desorption process were investigated. Maximum adsorption ≥98% was achieved at pH 3–7 after 20 min of contact time and the relative standard-deviation values were ≤5%. Adsorbed metal ions have been desorbed with 10 mL of 2 M HCl acid with the detection limit of 0.0157 μg m⁻¹. The Langmuir and Freundlich isotherm equations were used to describe adsorption behavior of the system at different temperatures. Kinetic and thermodynamic behavior of the adsorbent for Ni(II) ion preconcentration was also studied. The possible adsorption mechanism of Ni (II) ions onto modified adsorbent is also discussed. This method was applied efficiently to remove Ni (II) ions from environmental water samples.     

Chemical composition variations,allelopathic, and antioxidant activities of Symphyotrichum squamatum (Spreng.) Nesom essential oils growing in heterogeneous habitats

The present study aimed to analyze the chemical composition of Symphyotrichum squamatum EOs growing in two different habitats to explore the ecological implication on the EOs production and evaluate their antioxidant and allelopathic potentialities. The EOs from the aerial parts collected from coastal Mediterranean belt and inland abandoned habitats in the Nile Delta of Egypt, were extracted and analyzed using gas chromatography-mass spectrometry. Sixty compounds were characterized as overall constituents of EOs from both samples. Sesquiterpenes were the main component and represented by 69.77% and 88.68% from coastal and inland sample, respectively. The coastal sample attained a relatively high content of monoterpenes compared to the inland sample. Major compounds from the EOs of the coastal habitat sample, were humulene epoxide, (-)-spathulenol, (-)-caryophyllene oxide, germacrene D, and α-humulene representing 59.72%. However, β-pinene, germacrene D, α-humulene, α-muurolene, humulene epoxide, (-)-caryophyllene oxide, and β-cadinene were the major compounds of EOs of the inland habitat sample, representing 63.70%. The correlation analysis revealed more correlation between the Egyptian inland S. squamatum and the Japanese ecospecies. However, the Egyptian coastal S. squamatum and Turkish ecospecies were more correlated to each other. The present data suggested that chemotypes of S. squamatum maintain their typical pattern despite ecological or climatic differences. The EOs of S. squamatum showed moderate antioxidant activity, wherein coastal and inland EOs have an IC₅₀ value of 382.53 and 559.63 μL L⁻¹, respectively. Also, the EOs from both habitats showed moderate allelopathic activity against the noxious weed Bidens pilosa. However, the activity of the coastal sample was more than inland one and could be attributed to the content of the major compounds, especially the oxygenated terpenes.     

Structural,thermal, optical and conductivity studies of Co/ZnO nanoparticles doped CMC polymer for solid state battery applications

In this study, a simple chemical precipitation method was used to synthesize ZnO: Co²⁺ as nanoparticles. The solution casting technique was used for the preparation of polymer films of Carboxymethyl cellulose (CMC) doped with different contents (0.5, 1.5, 3, and 5 wt%) of ZnO/Co NPs. As shown by the X-ray diffraction, the average size of ZnO/Co crystallite of the NPs is 25.6 nm. Meanwhile, the addition of ZnO/Co reduced the semi-crystallinity of CMC. The Fourier transform infrared (FTIR) confirmed the interaction between the ZnO/Co NPs and the polymer CMC. The direct and indirect band gap (Eg) was reduced from (5.32–5.01 eV and 5.20 to 4.99 eV respectively) with the increase in ZnO/Co NPs content up to 3 wt% after this content the Eg is increased as shown by the UV–Vis spectra. In addition, the results of TGA displayed the decomposition of the nanocomposite to be little compared to that of the pure CMC indicating the success of fabrication of products. The improvement of the ionic conductivity was noticed upon the addition of ZnO/Co NPs into the polymer CMC system which can be explained in terms of an increase in amorphicity as shown by the impedance spectroscopic study. It was found that the optimum ionic conductivity (3.209 × 10⁻⁶ Scm⁻¹) at ambient temperature was higher for the sample containing 1.5 wt% ZnO/Co NPs with highest of amorphicity and the lowest total loss of weight. Therefore, the improvements in optical properties, thermal stability, and AC conductivity which were observed represent a strong support for the use of the nanocomposite films in the solid state battery applications.     

Numerical conformal mapping of multiply connected regions onto the second, third and fourth categories of Koebe?s canonical slit domains

This paper presents a boundary integral method for approximating the conformal mappings from any bounded or unbounded multiply connected region G onto the second, third and fourth categories of Koebe?s canonical slit domains. The method can be also used for calculating the conformal mappings of simply and doubly connected regions. The method is an extension of the author?s method for the first category of Koebe?s canonical slit domains (see [M.M.S. Nasser, Numerical conformal mapping via a boundary integral equation with the generalized Neumann kernel, SIAM J. Sci. Comput. 31 (2009) 1695-1715]). Three numerical examples are presented to illustrate the performance of the proposed method.     

EXACT EVALUATIONS OF FINITE TRIGONOMETRIC SUMS BY SAMPLING THEOREMS

We use the sampling representations associated with Sturm-Liouville difference operators to derive generalized integral-valued trigonometric sums. This extends the known results where zeros of Chebyshev polynomials of the first kind are involved to the use of the eigenvalues of difference operators, which leads to new identities. In these identities Bernoulli’s numbers play a role similar to that of Euler’s in the old ones. Our technique differs from that of Byrne-Smith (1997) and Berndt-Yeap (2002).     

Litter on the beaches of the Red Sea of Yemen

Distribution of litter: ropes, netting, lamb bulbs, foot wear, plastic bags, bottles, aluminum cans, cardboard, wood loges, rubber, polystyrene blocks and plastic sheets accumulating on Red Sea beaches of Yemen were examined. The results of the study reflected these wastes to be varied from a region to region but they were similar in almost all-coastal areas. Most of the litter were plastics including food bags, oil and water bottles, bait bags, and also vehicles tires. Most of pollution occurred from the sea, due to the heavy traffic and to the fishing vessels, which fish in the area.