Oviposition Deterrence and Ovicidal Activity of Birbira (Melletia furrgunia) on Diamondback Moth (Plutella xylostella) (Lepidoptera: Plutellidae)

The efficacy of different polar and non-polar solvent extracts of Birbira, Melletia furrginea (Hochst.) Baker tree seeds namely: Water, Acetic acid, Acetone, Chloroform, Toluene, and Hexane at different rates were evaluated on Diamondback moth, Plutella xylostella L. oviposition and egg mortality under laboratory conditions. The leaf dipping method was used to run both assays. In the assay, full Oviposition deterrence was recorded at the higher rates of polar solvent extracts. Significantly higher egg un-hatchability was recorded only at the higher rates for non-polar extracts. Eggs mortality caused by extracts with Water and Acetone was very high, and have much smaller LC50 values. In contrast, LC50 was higher for the other extracts. However, there was a constant increase in the percent kill of egg mass with the increase in the extract concentration. From this study, it is evident that M. furrgunia extracts with different solvents possess significant oviposition deterrence and ovicidal effect on P. xylostella.

Cyclopentasiloxane (D5) as a Non-Polar Masking Agent for Water-Sensitive Substrates During Polar Solvent Treatment

D5 (decamethylcyclopentasiloxane), a non-polar solvent that evaporates slowly, was tested for its suitability as a temporary masking agent for water-sensitive media on paper objects undergoing aqueous treatment. Three different treatment-related settings were tested on five different paper types, some prepared with water-soluble inks. In 10-min water immersion treatments, D5 proved largely ineffectual in protecting the water-soluble inks. In conjunction with melt-applications of cyclododecane, the addition of D5 enhanced its barrier function only in one case. To test the ability of D5 to prevent tideline formation, the test samples received applications of water, acetone, and a water-ethanol-mixture, creating an interface with freshly D5-impregnated areas. The papers were evaluated visually (VIS, UVA), some after artificial aging. D5 diminished the formation of visible tidelines in the two internally sized papers with low water absorbency in contact with acetone and the ethanol-water mixture, but did not prevent tidelines in contact with water. It also did not protect water-absorbent paper. The results indicate that D5, which is miscible with ethanol and acetone, may disperse tidelines caused by these solvents, but it proved largely insufficient for protecting media during water immersion.

Modeling of the interaction of porphyrin molecules in a nonpolar solvent

The article presents the data of a theoretical molecular dynamics study of the interaction between a pair of porphyrin molecules, i.e. symmetrically substituted 5,10,15,20-tetra (4-n-methyloxyphenyl) porphyrin (P) and asymmetrically substituted 5-(4 hydroxyphenyl)-10,15,20-tris (4-n-methyloxyphenyl) porphyrin (P-OH). We studied three systems, each of which consisted of a pair of porphyrin molecules (P || P, P-OH ↑↑ P-OH and P-OH ↑↓ P-OH) and chloroform molecules as a non-polar solvent. The effect of substitution, different orientations of asymmetrically substituted molecules and temperature on the geometry and energy of the system was investigated. It was shown that all three systems show signs of a true solution with chloroform as a solvent; the distance between asymmetrically substituted P-OH molecules was less than in the case of two P molecules. This may serve as an indirect evidence that the molecules are not prone to aggregation in the presence of chloroform.

Phytochemical screening and antimicrobial activity of Haematostaphis barteri

The aim of this work was to carry out the phytochemical screening and antimicrobial activities of Haematostaphis barteri. The method of cold maceration was used in the extraction by serial exhaustive extraction method which involves successive extraction with solvents of increasing polarity from a non-polar (hexane) to a more polar solvent (methanol) to ensure that a wide polarity range of compound could be extracted. The results showed that flavonoids, terpenes, terpenes, tannins, and saponins are present in all the leaf extracts. The result of the antimicrobial activity obtained from the extracts of the leaf of Haematostaphis barteri revealed that all the crude extracts of the leaf inhibited or exhibited antibacterial activity against Salmonella paratyphi, Staphylococcus aureus, Escherichia coli, and Penicillium spp. All the extracts did demonstrate antimicrobial activity against Aspergillus niger. The plant H. barteri is commonly used traditionally for the treatment of diarrhoea, wound, headache, malaria, dysentery and fevers. The overall results confirm the significance of the use of the plant in traditional medicinal treatment of diarrhea, wound, headache, malaria, dysentery and fevers, in line with reported claims.

IMINATION OF CHITOSAN NANOFIBERS IN A HETEROGENEOUS SYSTEM. SYNTHESIS OPTIMIZATION AND IMPACT ON FIBER MORPHOLOGY

The paper aimed to prepare imino-chitosan fibers by the imination reaction in a heterogenous system, targeting the improvement of anti-pathogenic activity. To this end, porous neat chitosan fibers were prepared by electrospinning of the polyethylene glycol/chitosan blend, followed by polyethylene glycol removal. Imination of the neat chitosan fibers was carried out in three liquid phase systems using solvents of different polarity and, consequently, different ability to swell the solid phase chitosan fibers. The successful imination was qualitatively and quantitatively assessed by FTIR and 1H-NMR spectroscopy, and the impact of the liquid phase on the fibers’ morphology was evaluated by SEM, POM and AFM microscopy. Further, the antimicrobial activity of the imino-chitosan fibers was investigated on relevant bacterial and fungal strains. It was concluded that the prior swelling in water of the fibers improved the imination degree, while the use of a less polar solvent, such as toluene, favored the preservation of the fibrous morphology. The imination with an antimicrobial aldehyde endowed the chitosan fibers with the ability to create a physical barrier against pathogens.

In Silico Modeling of the Influence of Environment on Amyloid Folding Using FOD-M Model

The role of the environment in amyloid formation based on the fuzzy oil drop model (FOD) is discussed here. This model assumes that the hydrophobicity distribution within a globular protein is consistent with a 3D Gaussian (3DG) distribution. Such a distribution is interpreted as the idealized effect of the presence of a polar solvent—water. A chain with a sequence of amino acids (which are bipolar molecules) determined by evolution recreates a micelle-like structure with varying accuracy. The membrane, which is a specific environment with opposite characteristics to the polar aquatic environment, directs the hydrophobic residues towards the surface. The modification of the FOD model to the FOD-M form takes into account the specificity of the cell membrane. It consists in “inverting” the 3DG distribution (complementing the Gaussian distribution), which expresses the exposure of hydrophobic residues on the surface. It turns out that the influence of the environment for any protein (soluble or membrane-anchored) is the result of a consensus factor expressing the participation of the polar environment and the “inverted” environment. The ratio between the proportion of the aqueous and the “reversed” environment turns out to be a characteristic property of a given protein, including amyloid protein in particular. The structure of amyloid proteins has been characterized in the context of prion, intrinsically disordered, and other non-complexing proteins to cover a wider spectrum of molecules with the given characteristics based on the FOD-M model.

Monolayer graphene membranes for molecular separation in high-temperature harsh organic solvents

The excellent thermal and chemical stability of monolayer graphene makes it an ideal material for separations at high temperatures and in harsh organic solvents. Here, based on understanding of solvent permeation through nanoporous graphene via molecular dynamics simulation, a resistance model was established to guide the design of a defect-tolerant graphene composite membrane consisting of monolayer graphene on a porous supporting substrate. Guided by the model, we experimentally engineered polyimide (PI) supporting substrates with appropriate pore size, permeance, and excellent solvent resistance and investigated transport across the resulting graphene-covered membranes. The cross-linked PI substrate could effectively mitigate the impacts of leakage through defects across graphene to allow selective transport without defect sealing. The graphene-covered membrane showed pure solvent permeance of 24.1 L m−2 h−1 bar−1 and stable rejection (∼90%) of Allura Red AC (496.42 g mol−1) in a harsh polar solvent, dimethylformamide (DMF), at 100 °C for 10 d.

Research of Polyphenylenesulphide Synthesis Depending on Nature and Comonomer Rating

Investigated the synthesis of polyphenylene sulfide in the environment of an aprotic polar solvent based on p-dichlorobenzene and p-dibromobenzene according to the nature comonomer rating. Infrared spectroscopy and thermogravimetric analysis of the obtained samples are presented.