Structural and optical properties of Zn doped CuInS2 thin films

Copper indium sulphide (CIS) films were deposited by spray pyrolysis onto glass substrates from aqueous solutions of copper (II) sulphate, indium chloride and thiourea using compressed air as the carrier gas. The copper/indium molar ratio (Cu/In) in the solution 1(1:1) and the sulphur/copper ratio (S/Cu) was fixed at 4. Structural properties of these films were characterized. The effects of Zn (0–5%) molecular weight compared with CuInS₂ Source and different substrate temperatures on films properties were investigated using X-ray diffraction (XRD) and optical transmission spectra. Optical characteristics of the CuInS₂ films have been analysed using spectrophotometer in the wavelength range 300–1100 nm. The absorption spectra of the films showed that this compound is a direct bandgap material and gap values varied between 1·55 and 1·57 eV, depending on the substrate temperatures. Zn-doped samples have a bandgap energy of 1·55–1·95 eV. It was observed that there is an increase in optical bandgap with increasing Zn % molecular weight. The optical constants of the deposited films were obtained from the analysis of the experimentally recorded transmission and absorption spectral data. The refractive index, n and dielectric constants, ε ₁ and ε ₂, were also discussed and calculated as a function of investigated wavelength range and found it dependent on Zn incorporation. We found that the Zn-doped CuInS₂ thin films exhibit P-type conductivity and we predict that Zn species can be considered as suitable candidates for use as doped acceptors to fabricate CuInS₂-based solar cells. The paper presents a study concerning the influence of deposition parameters (temperature of the substrate and concentration of Zn (1–5)% from 0·16 M ZnCl₂) on the quality of CuInS₂ thin films achieved by spray pyrolysis on glass substrate from solutions containing 0·02 M CuCl₂·2H₂O, 0·16 M thiourea and 0·08 M In₂Cl₃·5H₂O.     

NUMERICAL SIMULATION OF SPHERICAL, CYLINDRICAL AND AXIAL BUBBLE CLOUDS COLLAPSE

The nonlinear dynamics of a spherical,cylindrical and axial cloud of cavitation bubbles were numerically simulated in order to learn more about the physical phenomena occurring in the cloud cavitation....     

The effect of processing temperatures on the quality of labneh made by ultrafiltration

Twelve batches of labneh were manufactured by using the traditional method and also by ultrafiltration (UF) of yogurt at temperatures ranging from 35°-55° C. The labneh samples contained 21.3–26.4% total solids (including minerals and unmetabolized lactose), 6.6–9.3% protein and 9.8–12.6% fat. The highest flux rate during UF was observed at temperatures 50° C, but the total viable counts of the starter organisms were lower when compared with labneh concentrated at 45° C. Portions of each of the labneh samples were smoothed using a lactic curd homogenizer fitted with different homogenizer heads (D-170 and D-280). Homogenization markedly affected the firmness of labneh and is therefore recommended to smooth the product using homogenizer head D-280 because it causes less turbulence.     

Data evaluation of 169Yb-producing reactions by charged particles

Excitation functions for 169Yb production on low-medium energy accelerators, i.e. proton on 169Tm and natYb, deuteron on 169Tm, and 4He ion on natEr, were calculated by the ALICE/ASH and TALYS-1.0 codes. The target thickness was predicted by SRIM code. Theoretical integral yield for each reaction was compared with experimental data. The radionuclide purity of 169Yb from the 169Tm(p, n)169Yb reaction was determined, and maximum cross section predicted by the ALICE/ASH and TALYS-1.0 codes was about 182 and 154 mb at 11 and at 9 MeV, respectively.     

Solvothermal growth of single-crystal CdS nanowires

Cadmium sulfide (CdS) nanowires (NWs) were prepared by the solvothermal method using ethylenediamine as a solvent. Two sets of CdS NWs were synthesized at 160 and 200 °C for various reaction durations (3?5, 7, and 24 h). Scanning/tunneling electron microscopy was used to examine the surface morphology of the grown NWs. Their dimensions are found to depend on the reaction temperature and duration. The CdS NWs grown at 200 °C for all durations are longer than those prepared at 160 °C, with diameters ranging from 15 to 40 nm. A three-armed structure is exhibited by all the samples. The grown CdS NWs display a hexagonal wurtzite phase and grows along the \(\mathbf {\left \langle {001}\right \rangle }\) direction. The optical absorption of the grown NWs shows a sharp absorption edge with a blueshift, which indicates an expansion of the optical band gap. All prepared samples show two emission peaks in their photoluminescence spectra. The emission peak location depends on the reaction temperature and duration. The CdS NWs prepared at 160 °C show a sharp band–band emission compared with those prepared at 200 °C. Raman analysis indicates that the optical properties of the grown NWs are enhanced with increased temperature and reaction duration.     

Effects of guar gum and arabic gum on the physicochemical,sensory and flow behaviour characteristics of frozen yoghurt

This study investigated the effect of guar gum and arabic gum on physicochemical, sensory and flow behaviour properties of frozen yoghurt. The results indicated that gums significantly affected the viscosity, overrun and melting rate of frozen yoghurt. The highest overrun value was observed in sample containing 0.5% arabic gum. Frozen yoghurt containing 0.3% guar gum had the highest viscosity. The longest first dripping time was observed in sample containing 0.5% arabic gum. Flow behaviour of samples showed that all frozen yoghurts exhibited shear thinning behaviour. Guar gum at a concentration of 0.2% and arabic gum at a concentration of 0.5% presented the best total acceptability. The results of this study revealed that the frozen yoghurt produced with arabic gum had the better overall sensory and physicochemical characteristics.     

Survival of Lactobacillus casei,Lactobacillus plantarum and Bifidobacterium bifidum in free and microencapsulated forms on Iranian white cheese produced by ultrafiltration

Survival of probiotic strains Lactobacillus casei ( ATCC 39392 ), Lactobacillus plantarum ( ATCC 8014 ) and Bifidobacterium bifidum ( ATCC 29521 ) was investigated either in microencapsulated or in free form in the Iranian white cheese produced by ultrafiltration technique. The results indicated that the survival of encapsulated probiotic bacteria was higher than free cells. Both free and microencapsulated forms were successful in keeping counts of L. casei, L. plantarum and B. bifidum in the cheese high enough for the therapeutic minimum (10⁶–10⁷ cfu/g) after 60 days. Addition of probiotic adjunct also did not alter the chemical composition, but pH was lower in probiotic cheeses.     

A hybrid electronic energy meter design

This paper describes an electronic energy meter to replace the conventional Ferraris type. The design avoids the inherent multiplication of two analogue signals. Instead, a novel technique is to apply the two signals involved in energy measurement to a voltage-to-frequency converter together with a hybrid circuit employing a dual-slope analogue-to-digital converter that gives an output indicative of load consumed energy.