Study the Band Energy Structure and Absorption Coefficient for PbSe Thin Films

The PbSe alloy was prepared in evacuated quarts tubs by the method of melt quenching from element, the PbSe thin films prepared by thermal evaporation method and deposited at different substrate temperature (Ts) =R.T ,373 and 473K . The thin films that deposited at room temperature (R.T=303)K was annealed at temperature, Ta= R.T, 373 and 473K . By depended on D.C conductivity measurements calculated the density of state (DOS), The density of extended state N(Eext) increases with increasing the Ts and Ta, while the density of localized state N(Eloc) is decreased . We investigated the absorption coefficient (?) that measurement from reflection and transmission spectrum result, and the effect of Ts and Ta on it , also we calculated the tail width for each prepared films

Phytophthora infestans Has a Plethora of Phospholipase D Enzymes Including a Subclass That Has Extracellular Activity

In eukaryotes phospholipase D (PLD) is involved in many cellular processes. Currently little is known about PLDs in oomycetes. Here we report that the oomycete plant pathogen Phytophthora infestans has a large repertoire of PLDs divided over six subfamilies: PXPH-PLD, PXTM-PLD, TM-PLD, PLD-likes, and type A and B sPLD-likes. Since the latter have signal peptides we developed a method using metabolically labelled phospholipids to monitor if P. infestans secretes PLD. In extracellular medium of ten P. infestans strains PLD activity was detected as demonstrated by the production of phosphatidic acid and the PLD specific marker phosphatidylalcohol

From Starburst to Quiescence: Testing AGN feedback in Rapidly Quenching Post-Starburst Galaxies

Post-starbursts are galaxies in transition from the blue cloud to the red sequence. Although they are rare today, integrated over time they may be an important pathway to the red sequence. This work uses SDSS, GALEX, and WISE observations to identify the evolutionary sequence from starbursts to fully quenched post-starbursts in the narrow mass range $\log M(M_\odot) = 10.3-10.7$, and identifies "transiting" post-starbursts which are intermediate between these two populations. In this mass range, $\sim 0.3\%$ of galaxies are starbursts, $\sim 0.1\%$ are quenched post-starbursts, and $\sim 0.5\%$ are the transiting types in between. The transiting post-starbursts have stellar properties that are predicted for fast-quenching starbursts and morphological characteristics that are already typical of early-type galaxies. The AGN fraction, as estimated from optical line ratios, of these post-starbursts is about 3 times higher ($\gtrsim 36 \pm 8 \%$) than that of normal star-forming galaxies of the same mass, but there is a significant delay between the starburst phase and the peak of nuclear optical AGN activity (median age difference of $\gtrsim 200 \pm 100$ Myr), in agreement with previous studies. The time delay is inferred by comparing the broad-band near NUV-to-optical photometry with stellar population synthesis models. We also find that starbursts and post-starbursts are significantly more dust-obscured than normal star-forming galaxies in the same mass range. About $20\%$ of the starbursts and $15\%$ of the transiting post-starbursts can be classified as the "Dust-Obscured Galaxies" (DOGs), while only $0.8\%$ of normal galaxies are DOGs.The time delay between the starburst phase and AGN activity suggests that AGN do not play a primary role in the original quenching of starbursts but may be responsible for quenching later low-level star formation during the post-starburst phase.Comment: 30 pages, 18 figures,accepted to Ap

No evidence for feedback: Unexceptional Low-ionization winds in Host galaxies of Low Luminosity Active Galactic Nuclei at Redshift z ~1

We study winds in 12 X-ray AGN host galaxies at z ~ 1. We find, using the low-ionization Fe II 2586 absorption in the stacked spectra, that the probability distribution function (PDF) of the centroid velocity shift in AGN has a median, 16th and 84th percentiles of (-87, -251, +86) km/s respectively. The PDF of the velocity dispersion in AGN has a median, 84th and 16th percentile of (139, 253, 52) km/s respectively. The centroid velocity and the velocity dispersions are obtained from a two component (ISM+wind) absorption line model. The equivalent width PDF of the outflow in AGN has median, 84th and 16th percentiles of (0.4, 0.8, 0.1) Angstrom. There is a strong ISM component in Fe II 2586 absorption with (1.2, 1.5, 0.8) Angstrom, implying presence of substantial amount cold gas in the host galaxies. For comparison, star-forming and X-ray undetected galaxies at a similar redshift, matched roughly in stellar mass and galaxy inclination, have a centroid velocity PDF with percentiles of (-74, -258, +90) km/s, and a velocity dispersion PDF percentiles of (150, 259, 57) km/s. Thus, winds in the AGN are similar to star-formation-driven winds, and are too weak to escape and expel substantial cool gas from galaxies. Our sample doubles the previous sample of AGN studied at z ~ 0.5 and extends the analysis to z ~ 1. A joint reanalysis of the z ~ 0.5 AGN sample and our sample yields consistent results to the measurements above.Comment: 24 pages, 11 figures, accepted in Ap

Molecular features of new Peach Latent Mosaic Viroid variants suggest that recombination may have contributed to the evolution of this infectious RNA.

peer reviewe

Perceptions of Gauteng Beef Farmers on Significance of Practising Climate Smart Agriculture

Farmers are crucial role-players in agriculture, especially in beef farming. Daily farm activities affect climate change, either negatively or positively. Therefore, farmers’ ability to relate climate change with farm activities is highly imperative. A study was conducted to investigate perceptions of Gauteng beef farmers on significance of practising climate smart agriculture (CSA). Semi-structured key informant interviews were conducted with 57 beef cattle farmers from three areas (Bronkhorstspruit, Rust de Winter and Cullinan) of Tshwane region (Gauteng province). A fully detailed ethical statement was used to explain the study and request farmers’ participation. Data analysis was done using a Statistical Package for Social Sciences (SPSS) software version 20 with a significance of P \u3c 0.05. Majority (71%) of farmers who participated were males. Most (43%) of participated farmers were middle age, which indicates that farmers are now considering beef farming as a full-time job. Majority (60%) of participants had access to enough land (\u3e 700 hectares), which makes them suitable for practising CSA, provided they get appropriate training. Few participants showed good understanding of climate change (14%), global warming (14%), climate change reduction strategies (29%), cattle contribution to climate change (14%), adaptation strategies for climate change (29%) and the role played by CSA on reduction of farm operational costs (14%). Majority of farmers had average understanding of climate change (86%), global warming (86%), cattle contribution on global warming (71%), climate change adaptation strategies (71%), climate change reduction strategies (71%), recommendation of climate smart feed resource (71%) and impact of CSA on economic development (86%). Majority (71%) of participants identified water pollution as the only environmental hazard associated with beef farming, whereas few (29%) identified air pollution due to greenhouse gases emissions from poorly managed cattle manure. All participants (100%) showed good understanding regarding the benefits of practising CSA and its impact on food security. Furthermore, they were willing to adopt CSA and promote it to fellow farmers. There is a need for farmers’ training on CSA

Reduction of the structural iron in montmorillonite by electron transfer from catechol and its derivatives

Copyright © The Authors 2021. The structural Fe(III) in montmorillonite (MMT) clay has been reduced using catechol and its derivatives. It was found that the reduction process is pH-dependent and also depends on the ring substituents. If the catecholic ring has electron-donating substituents, reduction happens at high pH; if the catecholic ring has electron-withdrawing substituents, no reduction occurs. The process involves electron transfer from the hydroxy groups on the compounds to the active site at the iron atoms within the MMT lattice. This site acts as an electron acceptor (Lewis acid). Heat treatment of the reduced sample at 100-300 oC showed an enhancement of the Fe2+/Fe3+ ratio, which is attributed to an increase in the proportion of radicalic formation induced by dehydration. The MMT sample was added to the solutions of the catecholic compound and the slurries were stirred for 24 hours in order to reach equilibrium, then filtered, washed, and air-dried. The reactions were monitored using Mössbauer spectroscopy, x-ray powder diffraction, differential thermal analysis, electron spin resonance, infrared, and total surface area determination

Firing-activated interaction of montmorillonite with tin(Iv) and copper(ii) phthalocyanine dyes

Copyright © The Authors 2021. The adsorption of phthalocyanines Pcs complexes onto montmorillonite MMT clay differs from that of the other complexes like porphyrins, in that the adsorption process can be completed only after firing treatment of the solid mixture. The MMT particles act as a complex-hosting matrix, and the actual adsorption process of the complexes onto the MMT occurs only after firing. This firing treatment generates different colors on firing the solid mixtures to different temperatures. When tin(IV) phthalocyanine dichloride Sn(IV)PcCl2 complex is adsorbed onto the MMT, the chloride ligands are replaced by oxygen, and the complex is more protected from decomposition due to firing and solution effects. Both complexes, diamagnetic Sn(IV)PcCl2 and the paramagnetic Cu(II)Pc are found in a free radical state on the MMT surface or intercalated in the interlayer after firing, produced by electron transfer from the complexes to the MMT. It was found by X-ray powder diffraction investigation that firing treatment of the air-dried metal Pc-MMT samples induces intercalation of the complexes in the MMT interlayer