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Background: It is well-known that multi-layer films with nanostructure can give novel properties by interfacial phenomenon and quantum confinement effects. Nanostructured multi-layer thin films are presently being analyzed for their vast applications in the area of optoelectronics technology particularly photovoltaics. Hereof, two dimensional thin films with nanostructure are of prime importance due to their structure dependent optical, electrical, and opto-electronic properties. It has been revealed that these films exhibit quantum confinement effects with band gap engineering. The main focus of the research is to evaluate the effect on structural and optical properties with number of layers. Methods: Nanostructured SnO2-Ge multi-layer thin films were fabricated using electron beam evaporation and resistive heating techniques. Alternate layers of SnO2 and Ge were deposited on glass substrate at a substrate temperature of 300 °C in order to obtain uniform and homogeneous deposition. The substrate temperature of 300 °C has been determined to be effective for the deposition of these multi-layer films from our previous studies. The films were characterized by investigating their structural and optical properties. The structural properties of the as-deposited films were characterized by Rutherford Backscattering Spectroscopy (RBS) and Raman spectroscopy and optical properties by Ultra-Violet-Near infrared (UV-VIS-NIR) spectroscopy. Results: RBS studies confirmed that the layer structure has been effectively formed. Raman spectroscopy results show that the peaks of both Ge and SnO2 shifts towards lower wavenumbers (in comparison with bulk Ge and SnO2, suggesting that the films consist of nanostructures and demonstrate quantum confinement effects. UV-VIS-NIR spectroscopy showed an increase in the band gap energy of Ge and SnO2 and shifting of transmittance curves toward higher wavelength by increasing the number of layers. The band gap lies in the range of 0.9 to 1.2 eV for Ge, while for SnO2, it lies between 1.7 to 2.1 eV. Conclusion: Analysis of results suggests that the nanostructured SnO2-Ge multi-layer thin film can work as heterojunction materials with quantum confinement effects. Accordingly, the present SnO2-Ge multi-layer films may be employed for photovoltaic applications. Few relevant patents to the topic have been reviewed and cited. Keywords: Electron beam evaporation, photovoltaics, quantum confinement effect, resistive heating, Rutherford backscattering, SnO2-Ge multi-layer thin films.
Iron homeostasis is vital for normal physiology, but in the majority of circumstances, like iron overload, this equilibrium is upset leading to free iron in the plasma. This condition with excess iron is known as hemochromatosis, which has been linked to many side effects, including cancer and liver cirrhosis. The current research aimed to investigate active molecules from Streptomyces sp. isolated from the extreme environment of Bahawalpur deserts. The strain was characterized using 16 S rRNA sequencing. Chemical analysis of the ethyl acetate cure extract revealed the presence of phenols, flavonoids, alkaloids, and tannins. Multiple ultraviolet (UV) active metabolites that were essential for the stated pharmacological activities were also demonstrated by thin layer chromatography (TLC) and high-performance liquid chromatography (HPLC). Additionally, Gas chromatography/mass spectrometry (GC-MS) analysis revealed the primary constituents of the extract to compose of phenol and ester compounds. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to assess the extract's antioxidant capacity, and the results showed a good half-maximal inhibitory concentration (IC50) value of 0.034 µg/mL in comparison to the positive control ascorbic acid's 0.12 µg/mL. In addition, iron chelation activity of extract showed significant chelation potential at 250 and 125 µg/mL, while 62.5 µg/mL showed only mild chelation of the ferrous ion using ethylene diamine tetra acetic acid (EDTA) as a positive control. Likewise, the extract's cytotoxicity was analyzed through 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using varying concentrations of the extract and showed 51% cytotoxicity at 350 µg/mL and 65% inhibition of cell growth at 700 µg/mL, respectively. The bioactive compounds from Streptomyces sp. demonstrated strong antioxidant and iron chelating potentials and can prolong the cell survival in extreme environment.
Abstract Background Glaciers of the Hindu Kush region are highly susceptible to climate change. Recently, a severe glacial lake outburst flood (GLOF) hit the supraglacial region at the frontier of Dook Pal Glacier. Information on the bacterial community in a freshly appeared supraglacial lake after GLOF is essential to probe the bacterial distribution pattern after immediate unlocking from the supraglacial region. After GLOF, geochemistry and bacterial diversity, distribution, community structure, and function were examined in the lake-debris and melt-water. Results In general, concentrations of dissolved free amino acids were similar between lake-debris and melt-water, potentially toxic elements and cations were greater in lake-debris, and anions concentrations were greater in melt-water. In addition, there was comparable diversity in the glacial melt-water and lake-debris; Proteobacteria dominated in lake-debris (33.1–94.5%), while Proteobacteria (36.7–50.5%) and Firmicutes (44–62%) dominated in melt-water. It is more likely that Proteobacteria and Firmicutes shifted towards melt-water after GLOF, creating an uneven distribution of communities in the lake-debris; however, a relatively even distribution was maintained in melt-water. Genes responsible for metabolism and energy production were higher in lake-debris than in melt-water bacteria; whereas, genes for other cellular mechanisms were higher in melt-water than in lake-debris bacteria. Conclusions This study offers valuable datasets in understanding the bacterial diversity, distribution and function as a consequence of GLOF at the glacial frontier.
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