A study of many-year spectral variability of the Ae Herbig star HD 36112

We present the results of long-term high-dispersion spectral observations (R = 20000) of the Ae Herbig star HD 36112 in the regions of the Ha emission line and the NaI D resonance doublet lines. They show that parameters of the Ha emission line demonstrate complicated variability on several time scales: 1) variability from night to night caused by inhomogeneity of the circumstellar envelope; 2) variability on a time scale of about 1200d characterized by a variation of the equivalent width, intensity, and other emission parameters; 3) variability on a time scale of more than 4000d observed as a many-year trend in variations of parameters of the Ha emission line. We associate these results with variability of physical and kinematic conditions in the inner regions of the accretion disk and wind. The most probable mechanism of this variability is a process of planet formation in the circumstellar disk.

Influence of Zwitterionic CAPB on Flocculation of the Aqueous Cationic Guar Gum/Glauconite Suspensions at Various pH

The influence of the pseudoamphoteric zwitterionic surfactant cocamidopropylbetaine (CAPB) on the stabilizing flocculating properties of the aqueous suspensions of glauconite (GT) with cationic guar gum (CGG) at various pH values was investigated. The following techniques were used: turbidimetry, UV-VIS spectrophotometry, tensiometry, electrophoretic mobility measurements, SEM, CHN, XRD, and FT-IR. It was established that CGG is an effective glauconite flocculant. Moreover, the most probable mechanism that is responsible for flocculation is bridge flocculation resulting from polymer adsorption on the glauconite surface. The adsorption process is caused by electrostatic interactions between the negatively charged glauconite surface and the positively charged polymer. The amount of CGG adsorption increases with the increase of the pH, which was confirmed by the adsorption and zeta potential measurements. The addition of CAPB increases the amount of the polymer adsorption due to the formation of intermolecular polymer–surfactant complexes; however, it reduces flocculation effectiveness.

The probable mechanism of reduced androgen level in COVID-19 patients

COVID-19, caused by the SARS-CoV-2, has challenged the health care systems of the world. Although the pulmonary complications of the infection have received extensive attention, addressing the other complications (e.g., changes in androgen levels) could further provide a more efficient understanding of the disease, which might aid in combating it. Since the association between androgens and the expression and activity of SARS-CoV-2 receptors has been proven and anti-androgen-based therapies have been considered in this regard, addressing various aspects of androgen level changes can be constructive. The present paper examines the possible mechanisms of changes in androgen levels by the virus. It seems that the infection of the gonads by the SARS-CoV-2 could reduce the androgen levels by affecting different cellular pathways.

Bacillus-based nano-bioformulations for phytopathogens and insect–pest management

Background Recent concerns linked with the application of chemical pesticides and the increasing necessity of low inputs sustainable agriculture have put the use of microbial biocontrol agents and bio-pesticides to the forefront for their application against plant pathogens and insect–pest management. Results This review tended to scrutinize the prospects of microbial biocontrol agents and microbes-based nano-formulations against plant diseases and for pest management with emphasis on bacteria-based nanoparticles, especially derived from Bacillus species. It also tended to discuss the probable mechanism of action and effect on plant growth along with its prospects in a brief manner. Conclusion The use of microbial biocontrol agents offers effective, eco-friendly, and long-lasting management of plant diseases. The employment of nanotechnology in the field of biopesticides has emerged as a promising solution. Nano-biopesticides in the form of biologically derived active pesticides or compounds integrated as nanoparticles and integrated into a suitable polymer have application in insect–pest management.

Fluorescent Azasteroids through Ultrasound Assisted Cycloaddition Reactions

We report here the synthesis and optical spectral properties of several new azasteroid derivatives. The formation of these compounds was explained based on the most probable mechanism. The luminescent heterocycles were synthesized by 1,3-dipolar cycloaddition reactions between benzo[f]quinoline and methylpropiolate or dimethyl acetylenedicarboxylate (DMAD). A selective and efficient way for [3+2]-dipolar cycloaddition of benzo[f]quinolinium ylides under ultrasound (US) irradiation (20 kHz processing frequency) is presented. We report substantially higher yields under US irradiation, whereas the solvent amounts required are at least three-fold less compared to classical heating. The azasteroid derivatives are blue emitters with λmax of fluorescence around 430–450 nm. A certain influence of the azasteroid substituents concerning absorption and fluorescent properties was observed. Compounds anchored with a bulky pivaloyl group or without a C=O carbonyl group have shown increased fluorescence intensity.

An Efficient Synthesis of 2-CF3-3-Benzylindoles

The reaction of α-CF3-β-(2-nitroaryl) enamines with benzaldehydes afforded effectively α,β-diaryl-CF3-enones having nitro group. Subsequent reduction of nitro group by NH4HCO2-Pd/C system initiated intramolecular cyclization to give 2-CF3-3-benzylindoles. Target products can be prepared in up to quantitative yields. Broad synthetic scope of the reaction was shown. Probable mechanism of indole formation is proposed.

Mechanical Properties of WC-Si3N4 Composites With Ultrafine Porous Boron Nitride Nanofiber Additive

WC-10 wt.% Si3N4 composites toughened with ultrafine porous boron nitride nanofiber (0, 0.01, 0.05, 0.1, and 0.15 wt.%) were prepared for the first time by spark plasma sintering. Compared with the WC-Si3N4 composite sintered in the same condition, the obtained WC-10 wt.% Si3N4 composites with ultrafine porous boron nitride were found to possess better hardness and fracture toughness. In addition, the Si3N4 phase in the UPBNNF toughened composites did not exhibit traditional catastrophic fracture as indicated in most investigations. In this study, the phenomena are discussed, and a probable mechanism is elucidated. It is deduced that the approach could be extended to materials with a feature of internal liquid phase during the sintering process and could improve hardness and fracture toughness.

Transcriptome analysis of Nelumbo nucifera in response to antimony stress

To explore the probable mechanism of antimony stress resistance by Nelumbo nucifera and screen out relevant antimony-resistant genes, we conducted transcriptome sequencing of Nelumbo nucifera seeds treated by antimony at low, medium, and high concentrations (100, 500, 1000 mg/L respectively), screened differentially expressed genes (DEGs), and analyzed gene ontology classification and KEGG enrichment.Totally 18078 DEGs between antimony stress treatments and the control were identified, and 4192, 5850 and 8036 DEGs were found respectively.The pathways underlying the degradation of phosphopentose, limonene and pinene, the biosynthesis of flavonoid and ubiquinone, and the biosynthesis of terpenoids play critical roles in this responding process. The expressions of 7 genes validated by qPCR were consistent with the RNA-Seq results, which confirms the reliability of RNA-Seq results.This study on transcriptome analysis of Nelumbo nucifera under antimony stress provides a genetic resource and a theoretical basis for research on plant restoration of antimony pollution.