Lack Of Polar Groups Research Articles

Phytochemical characterization, antimicrobial properties and in silico modeling perspectives of Anacyclus pyrethrum essential oil

Medicinal plants are used widely in the treatment of various infectious diseases. One of these medical plants is Moroccan plants such as Anacyclus pyrethrum. In this study, the essential oil isolated from the leaves of Anacyclus pyrethrum (APEO) by the hydrodistillation method was analyzed using (GC/MS) analysis. A total of forty-four compounds were identified form the oil and the oxygenated monoterpenes were the most abundant class of compounds. The major identified compound is santolina alcohol (40.7 %), followed by germacrene-D (8.9 %). The in-vitro assessment of the antimicrobial efficacy of APEO encompassed an investigation involving six microbial strains, including two Gram-positive bacteria, four Gram-negative bacteria, and three fungal strains. The findings revealed noteworthy antibacterial and antifungal properties against all examined microorganisms, with inhibitory zone diameters ranging from 25.67 ± 0.06 mm to 25.19 ± 0.03 mm for Gram-positive bacteria and from 22.34 ± 0.01 mm to 14.43 ± 0.02 mm for Gram-negative bacteria, as determined through the disc-diffusion assay. In the case of antifungal activity, inhibitory zones ranged from 24.57 ± 0.04 mm to 18.37 ± 0.06 mm. Further evaluation revealed that the MIC values of Gram-positive bacteria were at the concentration 0.25 % v/v, while MBC values ranged from 0.25 % to 1.0 % v/v. The Gram-negative bacteria exhibited MIC values spanning from 0.5 % to 2.0 % v/v, with MBC values in the range of 0.5 %–2.0 % v/v. For the fungal strains, MIC values ranged from 0.5 % to 1.0 % v/v, while the MFC consistently remained at 1.0 % for all tested fungal strains. The assessment of the MBC/MIC and MFC/MIC ratios collectively indicates that A. pyrethrum EO possesses bactericidal and fungicidal attributes. The in silico study of bioavailability predictions for compounds in APEO based on six physicochemical properties show optimal physiochemical properties including size, lipophilicity, solubility, flexibility, and saturation. α-Pinene, limonene, germacrene D, and (E)-β-farnesene are non-polar due to their lack of polar groups, and the ADME profile indicates desirable properties for considering these compounds in drug development. Molecular docking investigation indicates that all the compounds of APEO reside well into the binding site of the DNA gyrase B enzyme of Staphylococcus aureus by mediating a number of significant interactions with the binding site residues. The ADME analysis suggested that the major compounds APEO possess desirable properties for further consideration in drug development. In light of these findings, APEO could serve as a natural source for the elaboration of new and active antimicrobial drugs.

Polydopamine-modified cellulose-based composite separator for inhibiting dendritic growth of lithium metal batteries

The inhomogeneous pore structure and lack of polar groups in lithium metal battery separators lead to uneven transport of Li+ through the separator, the uneven flux of Li+, and eventually the formation of lithium dendrites. Therefore, to provide uniform Li+ transport and inhibit the growth of lithium dendrites, a polydopamine-modified cellulose membrane (PDA-CM) was created by oxidative self-polymerizing dopamine and binding it to the surface and interface of the cellulose membrane through hydrogen bonds. The successful preparation of the PDA-CM separator by PDA-modified cellulose membrane by hydrogen bonds was proved by the FT-IR test. TGA, thermal shrinkage test, tensile strength test, FESEM, and porosity test results indicated that neither the PDA-CM nor the CM separators shrank at 160 °C, the PDA-CM separator also had better tensile strength (Stress = 31.1 MPa), and uniform pores (Porosity = 54.95 %) with homogeneous Li+ flux. The polar functional groups (-NH- and -OH) in PDA improved the electrolyte uptake rate (Electrolyte uptake rate = 469.77 %), the electrolyte retention (Electrolyte retention = 409.04 %), and electrolyte wettability (Contact angle = 18.35°) of the separator and promoted the uniform distribution of Li+ through the PDA-CM separator. In addition, the PDA-CM separator had better ionic conductivity (1.54 × 10−3 S·cm−1) and lower impedance (849 Ω). The catechol on the PDA molecule created strong adhesion between the separator and the lithium metal, reduced the local tension on the surface of the lithium metal and inhibited dendrite growth. The lithium metal anode remained smooth after cycling. The lithium metal battery prepared by the PDA-CM separator showed decent cycle performance and remained a high capacity retention rate (90.48 %) after 100 cycles. This study provides a new solution for the modification of cellulose-based lithium metal battery separators, which can achieve uniform transmission of Li+, inhibit the growth of lithium dendrites, and improve battery performance.

Research and synthesis of polyolefins materials

Polyolefins are widely used in our lives, such as food packaging materials, agricultural films, and lubricants, but the lack of polar groups that can make polyolefins compatible with other types of materials has limited the use of polyolefins. This has been a challenging and highly concerned issue in academia and industry. Therefore, it is great significance that we introduce polar groups into polyolefins to improve the use of performance to synthesize functional polyolefins. In this paper, we introduce the direct catalytic polymerization of polar α olefin monomers using rare earth catalysts, and the experimental data shows that we have obtained a higher molecular weight and better selectivity polar α olefin monomer of homopolymer. Subsequently, we determined the optimal reaction conditions for the synthetic polymer through screening of different reaction conditions.

Zinc borate modified multifunctional ceramic diaphragms for lithium-ion battery

Polyethylene(PE) diaphragm has become broadly used in lithium-ion battery systems because of its high strength, exceptional plasticity, and resistance to organic solvents. Nevertheless, the lack of polar groups on the surface of the PE diaphragms has a little significant effect on the ionic polarity of the electrolyte. Consequently, the electrolyte has poor wettability, the lithium-ion migration number t Li + (0.21) and the ion conductivity σ (0.63 mS/cm) still need to be further improved, which restricts its application to a certain extent. In this work, the high-purity zinc borate modified PE diaphragms with Lewis acid sites were prepared via a simple solid-state method. The multifunctional diaphragms modified by zinc borate have the following advantages: (1) The Zn–O bond and -BO 3 group in the structure have a polar bond and Lewis acid action, respectively, which can promote the desolvation of lithium ions and the dissociation of anions and cations, thereby increasing the concentration of free ions. In addition, zinc borate and anions have a specific binding effect, which can inhibit the migration of anions, consequently increasing t Li + (0.41) and σ (1.14 mS/cm); (2) Zinc borate was a commonly used flame retardant, which was conducive to improving the thermal stability of the PE diaphragms; (3) The surface of the modified diaphragms is rougher, which can increase the specific surface area of the diaphragm, hence enhancing its liquid absorption capacity. The electrochemical performance test results show that the modification of zinc borate can effectively improve the comprehensive performance of the PE diaphragm and the overall cycle stability and rate performance of the lithium iron phosphate battery.

In Situ Synthesis of Copper Nanoparticles on Dielectric Barrier Discharge Plasma-Treated Polyester Fabrics at Different Reaction pHs.

Polyester (PET) fabrics are widely applied in functional textiles due to their outstanding properties such as high strength, dimensional stability, high melting point, low cost, recyclability, and flexibility. Nevertheless, the lack of polar groups in the PET structure makes its coloration and functionalization difficult. The present work reports the one-step in situ synthesis of copper nanoparticles (CuNPs) onto the PET fabric employing sodium hypophosphate and ascorbic acid as reducing and stabilizing agents, at acidic (pH 2) and alkaline pH (pH 11). This synthesis (i) used safer reagents when compared with traditional chemicals for CuNP production, (ii) was performed at a moderate temperature (85 °C), and (iii) used no protective inert gas. The dielectric barrier discharge (DBD) plasma was used as an environmentally friendly method for the surface functionalization of PET to enhance the adhesion of CuNPs. The size of the CuNPs in an alkaline reaction (76-156 nm for not treated and 93.4-123 nm for DBD plasma-treated samples) was found to be smaller than their size in acidic media (118-310 nm for not treated and 249-500 nm for DBD plasma-treated samples), where the DBD plasma treatment promoted some agglomeration. In acidic medium, metallic copper was obtained, and a reddish color became noticeable in the textile. In alkaline medium, copper(I) oxide (Cu2O) was detected, and the PET samples exhibited a yellow color. The PET samples with CuNPs presented improved ultraviolet protection factor values. Finally, a minimal concentration of copper salt was studied to obtain the optimized antibacterial effect against Staphylococcus aureus and Escherichia coli. The functionalized samples showed strong antibacterial efficacy using low-concentration solutions in the in situ synthesis (2.0 mM of copper salt) and even after five washing cycles. The DBD plasma treatment improved the antibacterial action of the samples prepared in the alkaline medium.

Hydrophilization of Polyester Textiles by Nonthermal Plasma

Abstract Polyester is a popular class of material used in material engineering. With its 0.4% moisture regain, polyethylene terephthalate (PET) is classified as highly hydrophobic, which originates from its lack of polar groups on its backbone. This study used a parallel-plate nonthermal plasma dielectric barrier discharge system operating at medium pressure in dry air and nitrogen (N2) to alter the surface properties of PET fabrics to increase their hydrophilic capabilities. Water contact angle, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) were utilized to analyze any effect from the plasma treatment. The wettability analysis revealed a reduction in the contact angle of more than 80% within 5 min for both discharges. Scanning electron microscopy analysis showed no microscopic damage to the fiber structure, guaranteeing that the fabrics’ structural integrity was preserved after treatment. AFM analysis showed an increase in the nanometer roughness, which was considered beneficial because it increased the total surface area, further increasing the hydrophilic capacity. XPS analysis revealed a sharp increase in the presence of polar functional groups, indicating that the induced surface changes are mostly chemical in nature. Comparing that of untreated fabrics to treated fabrics, a Increase in water absorption capacity was observed for air-treated and N2-treated fabrics, when these fabrics were used immediately after plasma exposure.

Plasma Surface Modification of Blown Polyethylene Films for Uniform Atomic Layer Deposition of Al2O3

As polyethylene has unique physical characteristics such as low surface energy, low crystallization temperature, lack of polar groups, complicated lamellar structures, susceptibility to thermal degradation, and so on, most conventional coating techniques are not suitable for it. Atomic layer deposition (ALD) has many benefits over conventional coating techniques, and it can be a good candidate as a coating technique for polyethylene. In this study, a low-temperature ALD technique for depositing layers of Al2O3 on blown, high-density polyethylene (HDPE) films was investigated. The effect of plasma surface modification on the effectiveness of the ALD technique in Al2O3 layer formation was also studied.

“Covalent cationization method” for the analysis of polyethylene by mass spectrometry

Polyethylene and other polyolefins have not been amenable to mass spectrometric characterization of molecular mass distribution due to the ineffectiveness of conventional methods of cationization. The lack of polar groups, unsaturation, and aromaticity excludes cationization methods that are used commonly for polymers. A new method is introduced in which an organic cation is covalently bonded to the polymer to produce the necessary ionization for successful matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. A strong MALDI signal results from modified polymers that give no response in their unmodified form.

Simultaneous diffusion of a disperse dye and a solvent in PET film analyzed by Rutherford backscattering spectrometry

Poly(ethylene terephthalate) (PET) is a difficult fiber to dye from an aqueous dyebath due to its high degree of crystallinity and lack of polar groups. One method used to increase the dyeing rate of the fibers is the addition of an organic solvent, called a dye carrier, to the aqueous bath. This study utilized Rutherford backscattering spectrometry and neutron activation analysis to examine both simultaneous diffusion and individual diffusion characteristics of a disperse dye and dye carrier into PET film. The dye exhibited Fickian diffusion above and below glass transition temperature (Tg) of the PET film both in the presence and absence of solvent. The presence of carrier in the dyebath was found to increase the diffusion coefficient of the dye at each temperature condition; increasing from 10−14 to 10−11 cm2/s below Tg (65°C) and 10−12 to 10−10 cm2/s above Tg (90°C). Bromobenzene exhibited case II diffusion below Tg of the film, which indicates that the solvent is swelling the near surface regions of the film. This increase in void volume resulted in an increased dye uptake when films dyed inthe presence of carrier were compared with those dyed without carrier. In fact, the penetration depth of the dye was found to be equivalent to that of the swollen region of the film (∼ 600 nm) after 15 s. Above Tg, the bromobenzene exhibited Fickian diffusion. The coupling of the increased thermal motion of the polymer at the higher temperature and the solvent effect increased dye uptake when compared either with dye uptake at the lower temperature or with uptake when no solvent was present. The application of the dye and solvent simultaneously did not affect the diffusion mechanism of either species, leading to the conclusion that there was no competition for specific sites between these two species in the PET film. Similar results were obtained for chlorobenzene when used as the dye carrier. © 1996 John Wiley & Sons, Inc.

Fatty acid discrimination and ω-hydroxylation by cytochrome P450 4A1 and a cytochrome P4504A1/NADPH-P450 reductase fusion protein

The ω-hydroxylation of fatty acids by certain cytochrome P450 enzymes shows a degree of chain-length and regiospecificity which is remarkable in view of the conformational flexibility of these substrates, the strong similarity in properties among homologs, and the lack of polar groups (other than the carboxy terminus) with which to guide and strengthen enzyme-substrate interactions. To investigate the chemical basis for these features of ω-hydroxylation we designed and synthesized a series of lauric acid analogs and evaluated them as substrates and inhibitors of ω-hydroxylation catalyzed by cytochrome P4504A1 and a cytochrome P450 4A1/NADPH-P450 reductase fusion protein. Among n-alkanoic acids, lauric acid was found to have the optimum chain length for the fusion protein, as it does for native cytochrome P450 4A1. With both enzymes, chain shortening caused a precipitous drop in turnover while chain lengthening caused a gradual drop in turnover. The fusion protein ω-hydroxylated methyl laurate and lauryl alcohol about 1 10 th as efficiently as lauric acid, but it did not hydroxylate lauramide. 10-Methoxydecanoic acid underwent O-demethylation (via ω-hydroxylation). The branched substrate 11-methyllauric acid was hydroxylated efficiently and selectively at the ω-position. In contrast, the cyclopropyl analog 11,12-methanolauric acid was not detectably hydroxylated, although it induced Type I binding spectrum and inhibited lauric acid ω-hydroxylation by 43% at equimolar concentrations. ω-(Imidazolyl)-decanoic acid induced a Type II heme-binding spectrum and was an especially potent inhibitor of lauric acid hydroxylation. Collectively these data suggest that the active site of cytochrome P450 4A1 has an elongated tubular shape of definite length (ca. 14 Å) with a recognition site for polar groups (including but not limited to carboxyl) at its entrance and the (oxo)heme group at its terminus.

Influence of maleic anhydride as a coupling agent on the performance of wood fiber‐polystyrene composites

AbstractThe lack of polar groups in thermoplastics (e.g., in polystyrene) provides low adhesion with cellulosic fibers. To improve compatibility between reinforcement and matrix, maleic anhydride (MA) was selected as a coupling agent for wood fiber‐filled polystyrene composites. In general, the mechanical properties improved along with increased concentrations of MA, initiator (e.g., benzoyl peroxide) and wood fiber up to a certain limit and then decreased. The concentrations of MA and fiber which produced maximum improvements in the mechanical properties varied according to wood species, pulping techniques and type of polystyrene. Moreover, properties were further enhanced when another coupling agent (e.g., isocyanate) was used in addition to the MA.