Search Results (13)

In this work, we report a protective encapsulation intended as the final coating layer on solar cells. The formulation consists of polylactic (PLA)-based resin, modified with hexadecyltrimethoxysilane (HDTMS), epoxidized polybutadiene (EPB), and benzotriazole as a UV absorber with approximate weight fractions ranging from 20 to 60 wt% for PLA, 30–80 wt% for solvents (toluene and chloroform), and 0–5 wt% for HDTM, EPB, and benzotriazole with percentages 54.2%, 29.2%, and 16.7%, respectively. The encapsulating material, due to its insulating nature and high optical transparency, surpasses that of ethylene–vinyl acetate (EVA), as demonstrated in this study. To assess the protective effect of the developed formulation, the study focused on applying the modified PLA resin onto isolated methylammonium lead iodide (MAPI) perovskite films on glass substrates. The samples were prepared as isolated MAPI absorbers to specifically assess the intrinsic contribution of the dual encapsulation configuration at its real position in a complete solar cell stack, demonstrating that even this unoptimized perovskite film exhibits remarkable stability and excellent structural and optical retention over two months under the protective scheme (86% of its initial structural stability, as quantified from integrated XRD peak intensities, and 68% of its initial optical absorbance, determined from the integrated UV–Vis spectra), whereas the uncoated films showed significant degradation. Although MAPI was selected as a model system due to its well-known environmental instability, the proposed encapsulation material and methodology are not limited to this architecture and can, in principle, be applied to various photovoltaic technologies. These findings demonstrate the strong potential of the polylactic-based resin as an effective environmental barrier for solar cells and provide a solid foundation for future full-device integration studies. Full article

Citrus is an important economic plant in Thailand. The infection of citrus roots by Phytophthora nicotianae leads to root rot, reduced growth, and branch death. Although fosetyl aluminum and metalaxyl are commonly employed to address citrus root rot, they possess limitations in terms of their ability to diffuse to the root of citrus. Vernonia amygdalina leaf ethyl acetate extract (VLE) has been demonstrated to effectively inhibit Pythium deliense, a fungus closely related to Phytophthora nicotianae. This study aimed to investigate the anti-fungus activity of fractions obtained from the ethyl acetate extract of Vernonia amygdalina leaf against Phytophthora nicotianae, identify the most effective fraction, and formulate it into polymeric micro/nanoparticles using the electrospray process. The findings revealed that the VLE fraction eluted with ethanol:chloroform 1:1 had a high alkaloid content from metabolomic study and exhibited the potential to inhibit Phytophthora nicotianae at a concentration of 200 µg/mL. Consequently, this fraction was selected for incorporation into polymer blends of Poly Vinyl Alcohol/cellulose acetate to generate electrosprayed particles with a diameter of 0.97 ± 0.55 microns. These particles effectively suppressed in vitro Phytophthora nicotianae, thereby suggesting that VLE-containing electrosprayed particles have the potential to be applied and their in vivo performance in the treatment of citrus root rot evaluated in future experiments. Full article

An efficient and elegant method was developed for the preparation of substituted phenyl vinyl ketones using low-cost and commercially available ethyl chloroformate and diisopropylethylamine as reagents. This methodology was also applied to the synthesis of natural products such as mimosifoliol and quinolines. Frontier molecular orbital (FMO) studies on mimosifoliol were carried out to understand its chemical reactivity. Electron localization function (ELF) and localized orbital locator (LOL) analysis gave information about localized and delocalized electrons. Reduced density gradient (RDG) analysis gave information on steric, van der Waals, and hydrogen-bonding interactions. Molecular electrostatic potential (MEP) and Fukui functions gave information about nucleophilic and electrophilic attack. Nonlinear optical (NLO) analysis represented the mimosifoliol good NLO material. Molecular docking showed that the mimosifoliol compound had effectively inhibited the aspulvinone dimethylallyltransferase enzyme. Full article

The global challenge of oil pollution calls for the efficient selective recovery of oil or organics from oil–water mixtures. A pH-responsive carbon foam (CF) made from liquefied larch sawdust (LLS) with switchable wettability was fabricated in this work. After grafted with poly 4-vinyl pyridine (P4vp), the CF obtained a switchable wettability surface, which allowed the CF to exhibit superhydrophilicity and superhydrophobicity at different pH levels, respectively. The results revealed that the pH-responsive CF possessed a three-dimensional (3D) spongy-like skeleton and porous structure with a diameter between 50 and 200 µm. Thus, the pH-responsive CF could absorb 15–35 g/g of oil/organics in a neutral aqueous solution at pH = 7 and desorb all the absorbate within 40 s after immersion in an aqueous solution at pH = 1. Moreover, only about 2.8% loss was observed for organic (chloroform) absorption and recovery after reusing up to 15 cycles, which indicated promising prospects in oil and organic recovery. Full article

Solenostemma argel is a desert medicinal plant indigenous to African countries. This research aims to study the pharmacological properties of Solenostemma argel plant. Aerial parts (leaves and flowers) of Solenostemma argel (Delile) Hayane were tested for antibacterial activity, antioxidant activity, anticancer, and anti-inflammatory activity. Phenolic and flavonoid contents of the plant were characterized. There was an increase in the antioxidant activity of Solenostemma argel extract from 12.16% to 94.37% by increasing concentration from10 µg/mL to 1280 µg/mL. The most sensitive organism was S. epidermidis with chloroform extract. The MTT assay revealed that methanolic extracts of Solenostemma argel showed potent cytotoxic effects on the A549, Caco-2, and MDAMB-231 cell lines, respectively. The anti-inflammatory activity increased by increasing the concentration of methanolic extract of Solenostemma argel, using indomethacin as a standard. Gallic acid was the most abundant phenolic acid, followed by synergic acid and p-coumaric acid, respectively. Catechin, quercetin, luteolin, kaempferol and rutin flavonoids were also found in the methanolic extract. GC-mass analysis showed that aerial parts of Solenostemma argel were rich in 2-(5-methyl-5 vinyl tetrahydro-2-furanyl)-2-propanol (11.63%), hexanoic acid methyl ester (10.93%), 3-dioxolane,4-methyl-2-pentadecyl (9.69%), phenol, 2-(1,1-dimethylethyl) (8.50%). It can be concluded that Solenostemma argel methanolic extract contain natural bioactive constituents with potential medicinal importance such as antioxidants, antimicrobial, anti-inflammatory, and anticancer activities. Full article

The antifungal drugs currently available and mostly used for the treatment of candidiasis exhibit the phenomena of toxicity and increasing resistance. In this context, plant materials might represent promising sources of antifungal agents. The aim of this study is to evaluate for the first time the chemical content of the volatile fractions (VFs) along with the antifungal and anti-biofilm of Convolvulus althaeoides L. roots. The chemical composition was determined by gas chromatography coupled to a flame ionization detector and mass spectrometry. In total, 73 and 86 chemical compounds were detected in the n-hexane (VF1) and chloroform (VF2) fractions, respectively. Analysis revealed the presence of four main compounds: n-hexadecenoic acid (29.77%), 4-vinyl guaiacol (12.2%), bis(2-ethylhexyl)-adipate (9.69%) and eicosane (3.98%) in the VF extracted by hexane (VF1). n-hexadecenoic acid (34.04%), benzyl alcohol (7.86%) and linoleic acid (7.30%) were the main compounds found in the VF extracted with chloroform (VF2). The antifungal minimum inhibitory concentrations (MICs) of the obtained fractions against Candida albicans, Candida glabrata and Candida tropicalis were determined by the micro-dilution technique and values against Candida spp. ranged from 0.87 to 3.5 mg/mL. The biofilm inhibitory concentrations (IBF) and sustained inhibition (BSI) assays on C. albicans, C. glabrata and C. tropicalis were also investigated. The VFs inhibited biofilm formation up to 0.87 mg/mL for C. albicans, up to 1.75 mg/mL against C. glabrata and up to 0.87 mg/mL against C. tropicalis. The obtained results highlighted the synergistic mechanism of the detected molecules in the prevention of candidosic biofilm formation. Full article

Helichrysum caespititium (DC.) Sond. Ex Harv., (Asteraceae) is a medicinal plant indigenous to South Africa. Its non-polar extracts exhibit significant antimicrobial and, in particular, antigonorrheal activity. This study aimed at isolating and purifying the active antigonorrheal compound from its chloroform extract and validating its inhibition potential on quorum sensing (QS) and biofilm formation of multi-drug resistant (MDR) pathogens. Phytochemical investigation of aerial parts of H. caespititium afforded a diterpene lactone (CF6). The effect of CF6 on violacein production and biofilm formation was studied using in vitro quantitative violacein inhibition (Chromobacterium violaceum) and biofilm formation (Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Neisseria gonorrhoeae, and Pseudomonas aeruginosa). The structure of CF6 was characterized using FTIR, NMR, and UPLC-MS data accordingly, as 10-methyl-8-(propan-17-ylidene)naphthalen-9-yl)-11-vinyl-14-hydroxyfuran-16-one. The susceptibility testing of the pathogens against CF6 revealed Neisseria gonorrhoeae was noticeably susceptible with a MIC value of 60 µg/mL, while Streptococcus pyogenes and Staphylococcus aureus showed MIC of 125 µg/mL. All gram-negative pathogens, Escherichia coli, Klebsiella pneumonia and Pseudomonas aeruginosa were inhibited at 250 µg/mL. CF6 also inhibited the production of violacein by 51.88% at 250 µg/mL and prevented cell attachment by 40.76–81.18%, with N. gonorrhoeae being highly prohibited from forming biofilm. In conclusion, 10-methyl-8-(propan-17-ylidene)naphthalen-9-yl)-11-vinyl-14-hydroxyfuran-16-one is the first of its kind to be isolated from the non-polar (chloroform) extract of South African Helichrysum caespititium with antigonorrheal, antimicrobial, antiquorum sensing, and antibiofilm properties. The compound may serve as a drug candidate against MDR pathogens. Full article

Morphological transition between hexagonal and lamellar patterns in thin polystyrene–block–poly(4-vinyl pyridine) films simultaneously exposed to a strong in-plane electric field and saturated solvent vapor is studied with atomic force and scanning electron microscopy. In these conditions, standing cylinders made of 4-vinyl pyridine blocks arrange into threads up to tens of microns long along the field direction and then partially merge into standing lamellas. In the course of rearrangement, the copolymer remains strongly segregated, with the minor component domains keeping connectivity between the film surfaces. The ordering tendency becomes more pronounced if the cylinders are doped with Au nanorods, which can increase their dielectric permittivity. Non-selective chloroform vapor works particularly well, though it causes partial etching of the indium tin oxide cathode. On the contrary, 1,4-dioxane vapor selective to polystyrene matrix does not allow for any morphological changes. Full article

A series of coatings from poly(ethylene-co-vinyl acetate) (EVA) were obtained using the matrix-assisted pulsed laser evaporation (MAPLE) technique. By changing the process parameters, i.e., laser fluence and EVA co-polymer concentration in the target, coatings with various morphologies and topographies were produced. The evaluation of the film structure was based on an analysis of optical and atomic force microscopy and profilometry measurements. A detailed chemical structure investigation, conducted based on Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra, revealed that although the general structure was preserved, some alterations of ethylene (Et) and vinyl acetate (VAc) blocks took place. The most noticeable change was in the ester group that was transformed into ketone and carboxyl groups; nevertheless, some changes in the aliphatic main chain were also present. The chemical structure changes in EVA coatings took place regardless of the process parameters used. The use of chloroform as a solvent to dissolve the EVA copolymer was indicated as a possible reason of the changes as well as the tendency of EVA macromolecules to form clusters. Nevertheless, due to low level of structure alteration, it has been shown that the MAPLE technique can be successfully used to obtain coatings from polymers with more complex structures, which are soluble in a limited number of solvents. Full article

Volatile organic compounds (VOCs), with negative impacts on the aquatic ecosystem, are increasingly released into the environment by anthropogenic activities. Water samples were collected from five areas of the Han River Watershed (HRW) tributaries, South Korea, to detect 11 VOCs, which were classified as halogenated aliphatic hydrocarbons (HAHs) and aromatic hydrocarbons (AHs). Among the 11 VOCs, 1,1-dichloroethylene, 1,1,1-trichloroethane, and vinyl chloride were undetected. The highest concentration compounds were chloroform (0.0596 ± 0.1312 µg/L), trichloroethylene (0.0253 ± 0.0781 µg/L), and toluene (0.0054 ± 0.0139 µg/L). The mean concentration (0.0234 µg/L) and detection frequency (37.0%) of HAHs were higher than those of AHs (0.0036 µg/L, 21.0%, respectively). The Imjin Hantan River area exhibited the highest mean concentration (0.2432 µg/L) and detection frequency (22.9%), because it is located near industrial complexes, thus, highlighting their role as important VOC sources. However, the detected VOCs had lower concentrations than those permitted by the EU, WHO, USA, and South Korea drinking water guidelines. Ecological risks associated with the VOCs were estimated by risk quotient (RQ); consequently, the predicted no-effect concentration was 0.0029 mg/L, and the toluene and styrene RQ values were >1 and >0.5, respectively. The findings may facilitate policymakers in designing pollution control strategies. Full article

Coumarin-containing vinyl homopolymers, such as poly(7-methacryloyloxycoumarin) (P1a) and poly(7-(2′-methacryloyloxyethoxy)coumarin) (P1b), show a lower critical solution temperature (LCST) in chloroform, which can be controlled by the [2 + 2] photochemical cycloaddition of the coumarin moiety, and they are recognized as monofunctional dual-stimuli-responsive polymers. A single functional group of monofunctional dual-stimuli-responsive polymers responds to dual stimuli and can be introduced more uniformly and densely than those of dual-functional dual-stimuli-responsive polymers. In this study, considering a wide range of applications, organogels consisting of P1a and P1b, i.e., P1a-gel and P1b-gel, respectively, were synthesized, and their thermo- and photoresponsive behaviors in chloroform were investigated in detail. P1a-gel and P1b-gel in a swollen state (transparent) exhibited phase separation (turbid) through a temperature jump and reached a shrunken state (transparent), i.e., an equilibrium state, over time. Moreover, the equilibrium degree of swelling decreased non-linearly with increasing temperature. Furthermore, different thermoresponsive sites were photopatterned on the organogel through the photodimerization of the coumarin unit. The organogels consisting of homopolymers of coumarin-containing methacrylate exhibited unique thermo- and photoresponsivities and behaved as monofunctional dual-stimuli-responsive organogels. Full article

This paper reports the preparation and characterization of semi-interpenetrating polymer networks (semi-IPN) of poly(3-hydroxybutirate-co-3-hydroxyvalerate), PHBV, and poly (vinyl alcohol), PVA, with conductive polypirrole (PPy) nanoparticles. Stable hybrid semi-IPN (PHBV/PVA 30/70 ratio) hydrogels were produced by solvent casting, dissolving each polymer in chloroform and 1-methyl-2-pyrrolidone respectively, and subsequent glutaraldehyde crosslinking of the PVA chains. The microstructure and physical properties of this novel polymeric system were analysed, including thermal behaviour and degradation, water sorption, wettability and electrical conductivity. The conductivity of these advanced networks rose significantly at higher PPy nanoparticles content. Fourier transform infrared spectroscopy (FTIR) and calorimetry characterization indicated good miscibility and compatibility between all the constituents, with no phase separation and strong interactions between phases. A single glass transition was observed between those of pure PHBV and PVA, although PVA was dominant in its contribution to the glass transition process. Incorporating PPy nanoparticles significantly reduced the hydrogel swelling, even at low concentrations, indicating molecular interactions between the PPy nanoparticles and the hydrogel matrix. The PHBV/PVA semi-IPN showed higher thermal stability than the neat polymers and PHBV/PVA blend, which also remained in the tertiary systems. Full article

At 25.0 °C the specific rates of solvolysis for allyl and vinyl chloroformates have been determined in a wide mix of pure and aqueous organic mixtures. In all the solvents studied, vinyl chloroformate was found to react significantly faster than allyl chloroformate. Multiple correlation analyses of these rates are completed using the extended (two-term) Grunwald-Winstein equation with incorporation of literature values for solvent nucleophilicity (N_T) and solvent ionizing power (Y_Cl). Both substrates were found to solvolyze by similar dual bimolecular carbonyl-addition and unimolecular ionization channels, each heavily dependent upon the solvents nucleophilicity and ionizing ability. Full article