Plasma emission spectroscopy of solids irradiated by intense XUV pulses from a free electron laser

The FLASH XUV-free electron laser has been used to irradiate solid samples at intensities of the order 10¹⁶ W cm^?2 at a wavelength of 13.5 nm. The subsequent time integrated XUV emission was observed with a grating spectrometer. The electron temperature inferred from plasma line ratios was in the range 5–8 eV with electron density in the range 10²¹–10²² cm^?3. These results are consistent with the saturation of absorption through bleaching of the L-edge by intense photo-absorption reported in an earlier publication.     

Search for Uranium Source in Warcha Sandstone, Salt Range, Pakistan, using SSNTD Technique

The similarity in sedimentary depositional characteristics of the Warcha Sandstone of Nilawahan Group in the Salt Range to the uranium bearing sandstones of Siwalik Group in the foot hills of Himalaya and Sulaiman Ranges, Pakistan, tempted geologists to investigate the former group for the occurrence of uranium deposits in it. Like volcanic ash beds in Siwaliks, phosphatic nodules may be a possible source of uranium mineralization in Warcha Sandstone. Samples of phosphatic nodules occurring in the Warcha sandstone near Chakwal were collected and subjected to the solid state nuclear track detection technique for the determination of their uranium concentration. The uranium concentration in these samples ranges from (434±32) to (964±74) with an average of . The high uranium content indicates that the phosphatic nodules may be the possible source of uranium mineralization in Warcha Sandstone. These results are quite encouraging and favor the idea of exploring the area in detail for any possible occurrence of uranium deposits.     

SOME REACTIONS OF CHOLESTERYL N-PHENYL-PHOSPHORAMIDIC CHLORIDE AND RELATED COMPOUNDS

Abstract

Cholesteryl N-phenylphosphoramidic chloride has been converted to the corresponding phosphoramidic hydrazide and azide. The former compound was characterised by the preparation of a number of hydrazones, while the latter has been reacted with norbornene, dimethylsulphoxide, and triphenylphosphine. However, the azide did not react with decane, o-anisole, or butylamine. 17-Oxoandrost-5-ene-3β-yl N-phenylphosphoramidic chloride was prepared and was converted to the hydrazide, but a pure sample of the azide could not be isolated. Cholesteryl N-phenyl phosphoramidic triphenylphosphinimine has been reacted with eight carbonyl compounds and the structures of the products investigated. Cholesteryl N-cyclohexylphosphoramidic chloride was converted to the azide and the triphenylphosphinimine; the latter was reacted with acetone and p-nitrobenzaldehyde.

Cholesteryl phosphorodichloridate has been condensed with phenol, p-nitrophenol, and p-methoxyphenol to give the corresponding O-arylphosphorochloridates. The O-phenyl and O-p-methoxyphenyl phosphorochloridates have been converted to the corresponding azides, but the azide from the p-nitrophenyl derivative could not be isolated. The reactions of cholesteryl phosphorodichloridate with diethylamine, hydrazine, and sodium azide have also been examined; and cholesteryl phosphorodichloridothioate has been condensed with aniline and benzylamine.     

Influence of P<Superscript>+</Superscript>-ZnTe back surface contact on photovoltaic performance of ZnTe based solar cells

In order to improve photovoltaic performance of solar cells based on ZnTe thin films two device structures have been proposed and its photovoltaic parameters have been numerically simulated using Solar Cell Capacitance Simulator software. The first one is the ZnO/CdS/ZnTe conventional structure and the second one is the ZnO/CdS/ZnTe/P⁺-ZnTe structure with a P⁺-ZnTe layer inserted at the back surface of ZnTe active layer to produce a back surface field effect which could reduce back carrier recombination and thus increase the photovoltaic conversion efficiency of cells. The effect of ZnO, CdS and ZnTe layer thicknesses and the P⁺-ZnTe added layer and its thickness have been optimized for producing maximum working parameters such as: open-circuit voltage V_oc, short-circuit current density J_sc, fill factor FF, photovoltaic conversion efficiency η. The solar cell with ZnTe/P⁺-ZnTe junction showed remarkably higher conversion efficiency over the conventional solar cell based on ZnTe layer and the conversion efficiency of the ZnO/CdS/ZnTe/P⁺-ZnTe solar cell was found to be dependent on ZnTe and P⁺-ZnTe layer thicknesses. The optimization of ZnTe, CdS and ZnTe layers and the inserting of P⁺-ZnTe back surface layer results in an enhancement of the energy conversion efficiency since its maximum has increased from 10% for ZnO, CdS and ZnTe layer thicknesses of 0.05, 0.08 and 2 µm, respectively to 13.37% when ZnO, CdS, ZnTe and P⁺-ZnTe layer thicknesses are closed to 0.03, 0.03, 0.5 and 0.1 µm, respectively. Furthermore, the highest calculated output parameters have been J_sc?=?9.35 mA/cm², V_oc?=?1.81 V, η?=?13.37% and FF?=?79.05% achieved with ZnO, CdS, ZnTe, and P⁺-ZnTe layer thicknesses about 0.03, 0.03, 0.5 and 0.1 µm, respectively. Finally, the spectral response in the long-wavelength region for ZnO/CdS/ZnTe solar cells has decreased at the increase of back surface recombination velocity. However, it has exhibited a red shift and showed no dependence of back surface recombination velocity for ZnO/CdS/ZnTe/P?+?-ZnTe solar cells.     

Effect of neon mixing on vibrational temperature of molecular nitrogen plasma generated at 13.56 MHz

Optical emission spectroscopy is used to investigate the effect of neon mixing on the electron temperature and vibrational temperature of second positive and first negative system of nitrogen plasma generated by 13.56 MHZ RF generator. The electron temperature is determined from NeI lines intensities, using Boltzman's plot. The relative changes in vibrational population of N₂(C³Πu) and states with neon mixing are monitored by measuring the emission intensities of second positive and first negative system of nitrogen molecules. Vibrational temperature is calculated for the sequences Δν=0,1,−2, that follows the Boltzman's distribution. It is found that electron temperature as well as vibrational temperature of second positive and first negative system can be raised significantly by mixing neon in nitrogen plasma. Vibrational temperature at 250 watt RF power, of second positive system is raised up to 0.67 eV at 90% neon where as for first negative system it is raised up to 0.78 eV. It is found that vibrational temperature increases with the gas pressure.     

Synthesis of regenerated bacterial cellulose-zinc oxide nanocomposite films for biomedical applications

Regenerated bacterial cellulose (RBC) composites with zinc-oxide nanoparticles (ZnO) were prepared using a new strategy for enhanced biomedical applications of BC. Powdered BC was dissolved in N-methylmorpholine-N-oxide, and different concentrations of ZnO nanoparticles were mixed into the BC solution. RBC, RBC-ZnO1 (1 % ZnO) and ZnO-RBC2 (2 % ZnO) nanocomposite films were prepared by casting the solutions through an applicator. FE-SEM images confirmed the structural features and impregnation of the RBC films by nanoparticles. XRD analysis indicated the presence of specific peaks for RBC and ZnO in the composites. The RBC nanocomposites were found to have greatly enhanced thermal, mechanical and biological properties. Specifically, the degradation temperatures were improved from 334 °C for RBC to 339 and 344 °C for RBC-ZnO1 and RBC-ZnO2, respectively. The mechanical strength and Young’s modulus of the composites were also higher than those of pure RBC. The greatly improved antibacterial properties of the RBC-ZnO nanocomposites are the most striking feature of the present study. The bacterial growth inhibition measured for the RBC was zero, but reached up to 34 and 41 mm for RBC-ZnO1 and RBC-ZnO2, respectively. In addition to their antibacterial properties, the RBC-ZnO nanocomposites were found to be nontoxic and biocompatible with impressive cell adhesion capabilities. These RBC-ZnO nanocomposites can be used for different biomedical applications and have the potential for use in bioelectroanalysis.     

Evaluation of microbial loads,physical characteristics,chemical constituents and biological properties of radiation processed Fagonia arabica

Whole plant of Fagonia arabica with 3 different particle sizes (30, 50 and 70 mesh) were exposed to gamma radiation doses of 1–10 kGy from a Cobalt 60 source. A series of tests was performed in order to check the feasibility of irradiation processing of the plant. The applied radiation doses did not affect (P<0.05) pH and antimicrobial activities of the plant. The total weight of the dry extracts in methanol as well as water was found increased with irradiation. The irradiated samples showed significant increase in phenolic content and free radical scavenging activity using DPPH. Shortly after irradiation (on the day of radiation treatment) high amounts of free radicals were detected in the irradiated plant samples and the chemiluminescence measurements were generally found to be dose dependent. Maximum luminescence intensity was observed in case of samples with mesh size of 30 for all the radiation doses applied. After a period of one month the chemiluminescence signals of the irradiated samples approximated those of the controls. The study suggests that gamma irradiation treatment is effective for quality improvement and enhances certain beneficial biological properties of the treated materials.     

Biogenic Synthesis of Silver Nanoparticles Using Catharanthus roseus and Its Cytotoxicity Effect on Vero Cell Lines

Background: Type 2 diabetes mellitus (DM2) is a chronic and sometimes fatal condition which affects people all over the world. Nanotherapeutics have shown tremendous potential to combat chronic diseases—including DM2—as they enhance the overall impact of drugs on biological systems. Greenly synthesized silver nanoparticles (AgNPs) from Catharanthus roseus methanolic extract (C. AgNPs) were examined primarily for their cytotoxic and antidiabetic effects. Methods: Characterization of C. AgNPs was performed by UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and atomic force microscopy (AFM). The C. AgNPs were trialed on Vero cell line and afterwards on an animal model (rats). Results: The C. AgNPs showed standard structural and functional characterization as revealed by FTIR and XRD analyses. The zetapotential analysis indicated stability while EDX analysis confirmed the formation of composite capping with Ag metal. The cytotoxic effect (IC50) of C. AgNPs on Vero cell lines was found to be 568 g/mL. The animal model analyses further revealed a significant difference in water intake, food intake, body weight, urine volume, and urine sugar of tested rats after treatment with aqueous extract of C. AgNPs. Moreover, five groups of rats including control and diabetic groups (NC1, PC2, DG1, DG2, and DG3) were investigated for their blood glucose and glycemic control analysis. Conclusions: The C. AgNPs exhibited positive potential on the Vero cell line as well as on experimental rats. The lipid profile in all the diabetic groups (DG1-3) were significantly increased compared with both of the control groups (p < 0.05). The present study revealed the significance of C. AgNPs in nanotherapeutics.     

Pharmacological Inhibition of Endogenous Hydrogen Sulfide Attenuates Breast Cancer Progression

Hydrogen sulfide (H₂S), a gaseous signaling molecule, is associated with the development of various malignancies via modulating various cellular signaling cascades. Published research has established the fact that inhibition of endogenous H₂S production or exposure of H₂S donors is an effective approach against cancer progression. However, the effect of pharmacological inhibition of endogenous H₂S-producing enzymes (cystathionine-γ-lyase (CSE), cystathionine-β-synthase (CBS), and 3-mercaptopyruvate sulfurtransferase (3-MPST)) on the growth of breast cancer (BC) remains unknown. In the present study, DL-propargylglycine (PAG, inhibitor of CSE), aminooxyacetic acid (AOAA, inhibitor of CBS), and L-aspartic acid (L-Asp, inhibitor of 3-MPST) were used to determine the role of endogenous H₂S in the growth of BC by in vitro and in vivo experiments. An in silico study was also performed to confirm the results. Corresponding to each enzyme in separate groups, we treated BC cells (MCF-7 and MDA-MB-231) with 10 mM of PAG, AOAA, and L-Asp for 24 h. Findings reveal that the combined dose (PAG + AOAA + L-Asp) group showed exclusive inhibitory effects on BC cells’ viability, proliferation, migration, and invasion compared to the control group. Further, treated cells exhibited increased apoptosis and a reduced level of phospho (p)-extracellular signal-regulated protein kinases such as p-AKT, p-PI3K, and p-mTOR. Moreover, the combined group exhibited potent inhibitory effects on the growth of BC xenograft tumors in nude mice, without obvious toxicity. The molecular docking results were consistent with the wet lab experiments and enhanced the reliability of the drugs. In conclusion, our results demonstrate that the inhibition of endogenous H₂S production can significantly inhibit the growth of human breast cancer cells via the AKT/PI3K/mTOR pathway and suggest that endogenous H₂S may act as a promising therapeutic target in human BC cells. Our study also empowers the rationale to design novel H₂S-based anti-tumor drugs to cure BC.