Parabolic Trough Solar Collector – Design, Construction and Testing

This paper presents the design, construction and investigates an experimental study of a parabolic Trough Solar Collector (PTSC). It is constructed of multi – piece glass mirror to form the parabolic reflector (1.8 m ? 2.8 m) its form were checked with help of a laser and carbon steel rectangular as receiver. Sun tracker has been developed (using two – axis) to track solar PTSC according to the direction of beam propagation of solar radiation. Using synthetic oil as a heat transfer its capability to heat transfer and load high temperature (?400 oc). The storage tank is fabricated with stainless steel of size 50 L. The experimental tests have been carried out in Baghdad climatic conditions (33.3o N, 44.4o E) during selective days of the months October and November. The performance of PTSC is evaluated using outdoor experimental measurements including the useful heat gain, the thermal instantaneous efficiency and the energy gained by the storage tank oil. The storage tank oil temperature is increased from 30oc at 9:30h to 136oc at 13:30h without draw – off oil. The experimental result shows the average thermal efficiency was 42% which is fairly acceptable assessment results of a PTSC locally

Transition from amplified spontaneous emission to laser action in disordered media of R6G dye and TiO2 nanoparticles doped with PMMA polymer

A random laser (RL) based on organic Rhodamine 6G (R6G) laser- dye and TiO2 suspended nanoparticles have been prepared with polymethylmethacrylate (PMMA) as a host. Both liquid and spray-coated homogeneous film samples of 22.4-30.1µm thickness range were use. Optimum concentrations have been determined depending on the normal fluorescence spectra which give evidence that the laser dye provides amplification and TiO2 nanoparticles act as scatter center. At the optimum concentrations, results of the random laser (RL) under second harmonic Nd: YAG laser excitation show that the values of bandwidth at full width half-maximum (FWHM) and the threshold energy are about 9 nm and 15 mJ respectively, which represent the minimum value for the liquid samples in the current research. Correspondly, these values become 14 nm and 15 mJ for film sample. The broadening that can be attributed to the concentration quenching of a laser dye at high a concentration level has been observed

Thermodynamic study of interactions between ZnO and ZnO binding peptides using isothermal titration calorimetry

Whilst material specific peptide binding sequences have been identified using a combination of combinato-rial methods and computational modelling tools, a deep molecular level understanding of the fundamental principles through which these interactions occur and in some instances modify the morphology of inorganic materials is far from being fully realized. Understanding the thermodynamic changes that occur during peptide-inorganic interactions and correlating these to structural modifications of the inorganic materials could be the key to achieving and mastering con-trol over material formation processes. This study is a detailed investigation applying isothermal titration calorimetry (ITC) to directly probe thermodynamic changes that occur during interaction of ZnO binding peptides (ZnO-BPs) and ZnO. The ZnO-BPs used are reported sequences G-12 (GLHVMHKVAPPR), GT-16 (GLHVMHKVAPPR-GGGC) and alanine mutants of G-12 (G-12A6, G-12A11 and G-12A12) whose interaction with ZnO during solution synthesis studies have been extensively investigated. The interactions of the ZnO-BPs with ZnO yielded biphasic isotherms comprising both an endo-thermic and an exothermic event. Qualitative differences were observed in the isothermal profiles of the different pep-tides and ZnO particles studied. Measured ΔG values were between -6 and -8.5 kcal/mol and high adsorption affinity val-ues indicated the occurrence of favourable ZnO-BP-ZnO interactions. ITC has great potential in its use to understand peptide-inorganic interactions and with continued development, the knowledge gained may be instrumental for simplifi-cation of selection processes of organic molecules for the advancement of material synthesis and design

Molecularly Imprinted Nanospheres by Nonaqueous Emulsion Polymerization

The preparation of nanosized, molecularly imprinted polymer particles by nonaqueous emulsion polymerization is presented. Monodisperse cross-linked polymer nanospheres with a diameter of around 100 nm were synthesized using a standard monomer mixture of methacrylic acid and ethylene dimethacrylate, containing (+/-)-propranolol as a template. The rebinding efficiency of the resulting particles was determined by batch rebinding tests and isothermal titration calorimetry (ITC). The results indicate that the proposed imprinting process under nonaqueous conditions lead to particles with an enhanced capacity of template rebinding compared to both nonimprinted ones and to particles obtained by more conventional emulsion polymerization in water

Characterization of low pressure plasma-<i>dc</i> glow discharges (Ar, SF₆ and SF₆/He) for Si etching

723-730Low-pressure plasma reactor which is generated for SF6, SF6/He and Ar gases discharges between two metal electrodes (planer –parallel) using dc-high voltage power supply of 2 kV has been proposed. Paschen’s curves show the breakdown voltage of gases as a function of the parameter p*d which is the product of the pressure in the chamber (P=6.5´10-2-1.5´10-1 mbar) and the distance between the two electrodes (d=4.6 cm). The minimum breakdown voltages were found 450 V at pressure of 1.35´10-1mbar and 276 V at pressure of 4.3´10-1 mbar for SF6 and Ar, respectively. Current-voltage characteristics have been studied at different values of pressure (6.5´10-2-1.5´10-1 mbar) and inter-electrodes spacing (3.4, 4.2, 4.6, 5 cm). The SF6, SF6/He and Ar gases discharges plasmas in Si etching have been discusse

Persistently folded circular aromatic amide pentamers containing modularly tunable cation-binding cavities with high ion selectivity

10.1021/ja1035804Journal of the American Chemical Society132289564-9566JACS