Photosensitive activity of fabricated core-shell composite nanostructured p-CuO@CuS/n-Si diode for photodetection applications.

Development of photo detectors based on different semiconducting materials with high performance has been in progress in recent past, however, there is a lot of difficulties in developing the more effective photo detectors-based devices with high responsivity, detectivity and quantum efficiency. Hence, we have synthesized pure CuS and CuO@CuS core-shell heterostructure based photo detectors with high performance by simple and cost-effective two-step chemical co-precipitation method. The phase purity of CuS and CuO@CuS composite was observed by XRD analysis and the result were verified with Raman spectroscopy studies. Sphere like morphology of pure CuS and core-shell structure formation of CuO@CuS are observed with scanning and transmission electron microscopes. The presence of expected elements has been confirmed with EDX elemental mapping. Light harvesting photodiodes were fabricated by using n-type silicon substrate through drop cost method. Photo sensitive parameters of fabricated diodes were analyzed by I-V characteristics. The p-CuO@CuS (1:1)/n-Si diode owned a maximum photosensitivity (Ps) ∼ 7.76 × 104 %, photoresponsivity (R) ∼ 798.61 mA/W, external quantum efficiency ( E Q E )∼309.66 % and specific detectivity (D*) ∼ 8.19 × 1011 Jones when compared to p-CuS/n-Si diode. The obtained results revealed that the core/shell heterostructure of CuO@CuS is the most appropriate for photo detection.

A reliable chemiresistive sensor of nickel-doped tin oxide (Ni-SnO2) for sensing carbon dioxide gas and humidity.

Herein, we report the chemiresistive gas and humidity sensing properties of pristine and nickel-doped tin oxide (Ni-SnO2) gas sensors prepared by a microwave-assisted wet chemical method. The structural and optical properties are characterised using X-ray diffraction, scanning electron microscopy, scanning transmission electron microscopy, ultraviolet spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The structural elucidation and morphology analyses confirm a particle size of 32-46 nm, tetragonal rutile crystal structure and small cauliflower-type surface appearance. Nickel doping can tune the structure of NPs and morphology. The tested carbon dioxide gas and humidity sensing properties reveal a rapid sensing performance with high-to-moderate sensitivity. Also, the materials favour gas sensing because their sensitivity is enhanced with the increase in nickel concentration. The sensing results suggest that nickel is a vibrant metal additive to increase the gas sensitivity of the sensor. However, nickel doping decreases the electron density and increases the oxygen vacancies. Ultimately, the gas sensor produces highly rapid sensing with a response time of 4 s.

The rapid response and high sensitivity of a ruthenium-doped copper ferrite thin film (Ru-CuFe2O4) sensor.

A sensor displaying a rapid response and high sensitivity was developed by following a simple route. Ionic defects in this sensor were explored using X-ray diffraction analysis. In general, such defects arise from a mismatch of ionic radii, which actually improves the sensing performance. SEM and TEM images of the currently produced particles demonstrated negligible agglomeration, which greatly enhanced the flow of water molecules through the particles. The current sensor showed a rapid response to changes in humidity. Its sensing performance was classified into three different ranges of humidity. Of these humidity ranges, the sensor showed the highest sensitivity (8.84 MΩ per %RH) at low relative humidity (10-20% RH). Furthermore, the sensitivity fall off as the RH was increased from 20 to 99%. The sensor showed a rapid response time of 20 s. Also, the sensor showed 92.98% reproducibility and few effects of aging.

Investigation on growth, structure and characterization of succinate salt of 8-hydroxyquinoline: an organic NLO crystal.

8-Hydroxyquinolinium succinate (8-HQSU) has been synthesized and single crystals were grown from ethanol solvent by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated by single crystal X-ray diffraction analysis. It reveals that 8-HQSU crystallizes in monoclinic system with non-centro symmetric space group P2(1). FTIR, 1H and 13C NMR spectral investigations have been carried out to identify the vibrational modes of various functional groups and placement of proton and carbon in the 8-HQSU compound, respectively. UV-vis-NIR transmission spectrum shows the cutoff wavelength around 357 nm. In addition, a photoluminescence spectral analysis was carried out for 8-HQSU crystals. The thermal properties of crystals were evaluated from TGA and DTA techniques and the crystal was found to be stable up to 145°C. The dielectric studies show that the dielectric constant and dielectric loss decrease exponentially with frequency at different temperatures. Photoconductivity studies were carried out on the grown crystals it reveals the positive photo conducting nature. Powder second harmonic generation property of the crystal was confirmed by Kurtz and Perry powder SHG technique and it is found to be 1.3 times greater than that of KDP.

Synthesis, crystal growth and physiochemical characterization of organic NLO crystal: L-ornithinium dipicrate (LODP).

L-ornithinium dipicrate (LODP) has been synthesized and good quality single crystals were grown by slow evaporation method at room temperature. Single crystal XRD confirms that the grown crystal belongs to the monoclinic system with the noncentrosymmetric space group P21. Powder X-ray diffraction study confirms the crystalline nature of the compound. FTIR spectral analysis confirms the functional group in the synthesized compound. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. The optical absorption spectrum shows the absence of absorption between 475 nm and 800 nm. The dielectric measurements were carried out to estimate the dielectric parameters of the grown crystal in the frequency range from 50 Hz to 5 MHz at various temperatures. The second harmonic property has been investigated by Kurtz-Perry powder technique. The relative SHG efficiency of LODP is found to be 14.57 times greater than that of the reference material KDP.

Growth and characterization of L-alanine cadmium bromide a semiorganic nonlinear optical crystals.

A new semiorganic nonlinear optical crystal, l-alanine cadmium bromide (LACB) was grown from aqueous solution by slow solvent evaporation method at room temperature. As grown crystals were characterized for its spectral, thermal, linear and second order nonlinear optical properties. LACB crystallizes in orthorhombic system and unit cell parameters a=5.771(2)Å, b=6.014(4)Å, c=12.298(2)Å, α=ß=γ=90° and volume=426.8(3)Å(3). The mode of vibrations of different molecular groups present in the crystal was identified by FTIR study. The grown crystals were found to be transparent in the entire visible region. The thermal strength and the decomposition of the grown crystals were studied using TG/DTA and DSC analysis. Dielectric measurement revealed that the crystals had very low dielectric constant at higher frequency in room temperature. The mechanical behavior was studied by Vicker's microhardness tester. The grown crystal has negative photoconductivity nature. The fluorescence spectrum of the crystal was recorded and its optical band gap is about 3.356 eV. The NLO property of crystal using modified Kurtz-Perry powder technique with Nd:YAG laser light of wavelength 1064nm indicated that their second harmonic generation (SHG) efficiency was half that of pure KDP.

Synthesis, crystal growth, structural, thermal and optical properties of naphthalene picrate an organic NLO material.

Crystalline substance of naphthalene picrate (NP) was synthesized and single crystals were grown using slow evaporation solution growth technique. The solubility of the naphthalene picrate complex was estimated using different solvents such as chloroform and benzene. The material was characterized by elemental analysis, powder X-ray diffraction (XRD), nuclear magnetic resonance (NMR) and fourier transform-infrared (FT-IR) techniques. The electronic absorption was studied through UV-vis spectrophotometer. Thermal behavior and stability of the crystal were studied using thermogravimetric (TG) and differential thermal analysis (DTA) techniques. The second harmonic generation (SHG) of the material was confirmed using Nd:YAG laser.

Inhibition of cytolytic T lymphocyte maturation with ornithine, arginine, and putrescine.

L-Ornithine was shown to inhibit the development of cytolytic T lymphocytes (CTL) in mixed lymphocyte cultures (MLC). Lymphokines were unable to reverse the suppressive effect, and cytotoxic activity was not revealed by coupling ornithine-inhibited MLC cells to target cells with phytohemagglutinin (PHA). If addition of ornithine to MLC were delayed, sensitivity of CTL to inhibition was reduced after 24 hr and lost by 48 hr. Suppression of CTL development was not due to a toxic effect. MLC washed free of ornithine after 3 days produced detectable cytolytic activity within 24 hr of secondary culture, and to the same degree as the uninhibited MLC control within 48 hr. Cytotoxic cells generated in secondary cultures were Lyt-2+, did not kill the natural killer-sensitive YAC-1 cell line, and were shown to be antigen-specific by virtue of the findings that cytolysis and cold target inhibition were observed only with cells carrying the original, inducing H-2 haplotype. Cytolysis of target cells by normal CTL effector cells was not inhibited by L-ornithine. MLC depleted of accessory cells so that CTL activation was dependent upon addition of lymphokines remained susceptible to inhibition by ornithine. Our findings indicate that in the ornithine-inhibited MLC, CTL precursors undergo clonal expansion, but their maturation is arrested at a precytolytic stage. L-Arginine and putrescine also suppressed generation of CTL in primary MLC, and cells recovered from arginine- and putrescine-inhibited MLC developed control levels of CTL within 48 hr of secondary culture. Inhibition by putrescine was observed in tissue culture medium supplemented with human serum but not with fetal calf serum, presumably due to the presence of diamine oxidase activity in fetal calf serum. Similar to ornithine, the suppressive effects of arginine and putrescine on T lymphocytes were apparently selective for CTL because they did not inhibit mitogen activation with concanavalin A or the production of interleukin 2 and interleukin 3. These findings are consistent with a hypothesis that the inhibitory effects of ornithine, arginine, and putrescine are mediated by polyamines, and exerted on the differentiative stage of CTL development.