Ethanol Solution Research Articles

Green HPLC Enantioseparation of Chemopreventive Chiral Isothiocyanates Homologs on an Immobilized Chiral Stationary Phase Based on Amylose tris-[(S)-α-Methylbenzylcarbamate

Sulforaphane is a chiral phytochemical with chemopreventive properties. The presence of a stereogenic sulfur atom is responsible for the chirality of the natural isothiocyanate. The key role of sulfur chirality in biological activity is underscored by studies of the efficacy of individual enantiomers as chemoprotective agents. The predominant native (R) enantiomer is active, whereas the (S) antipode is inactive or has little or no biological activity. Here we provide an enantioselective high-performance liquid chromatography (HPLC) protocol for the direct and complete resolution of sulforaphane and its chiral natural homologs with different aliphatic chain lengths between the sulfinyl sulfur and isothiocyanate group, namely iberin, alyssin, and hesperin. The chromatographic separations were carried out on the immobilized-type CHIRALPAK IH-3 chiral stationary phase with amylose tris-[(S)-methylbenzylcarbamate] as a chiral selector. The effects of different mobile phases consisting of pure alcoholic solvents and hydroalcoholic mixtures on enantiomer retention and enantioselectivity were carefully investigated. Simple and environmentally friendly enantioselective conditions for the resolution of all chiral ITCs were found. In particular, pure ethanol and highly aqueous mobile phases gave excellent enantioseparations. The retention factors of the enantiomers were recorded as the water content in the aqueous-organic modifier (methanol, ethanol, or acetonitrile) mobile phases progressively varied. U-shaped retention maps were generated, indicating a dual and competitive hydrophilic interaction liquid chromatography (HILIC) and reversed-phase liquid chromatography retention mechanism on the CHIRALPAK IH-3 chiral stationary phase. Finally, experimental chiroptical studies performed in ethanol solution showed that the (R) enantiomers were eluted before the (S) counterpart under all eluent conditions investigated.

Exploration of phenolic profile from mangosteen (Garcinia mangostana L.) pericarp and their contribution to inhibitory effects on α-amylase and α-glucosidase

The aim of this study was to reveal the phenolic profile of mangosteen (Garcinia mangostana L.) pericarp and investigate their inhibitory effects on α-amylase and α-glucosidase. Mangosteen pericarp polyphenols (MPP) obtained by acetone extraction were fractionated with gradient ethanol elution. A total of twenty nine phenolic chemicals were found and quantified by UPLC-Q-TOF-MS/MS. MPP eluted by the 60% ethanol solution (MPP60%) showed the highest total phenolic content. Moreover, MPP60% displayed the greatest inhibition activities on α-amylase and α-glycosidase by competitive and mixed inhibitions. Mechanistically, the inhibitory effects of MPP60% on α-amylase and α-glucosidase involved the changes of the secondary structure as well as the static fluorescence quenching of these enzymes. Pearson correlation coefficients revealed that procyanidin B2, quercetin glucoside, and mangostain contributed most to inhibiting the activities of α-amylase and α-glucosidase. This study indicated that polyphenols from mangosteen pericarps can be developed into potential inhibitors of α-amylase and α-glucosidase, offering a viable strategy for the valorization of mangosteen pericarps.

Phenformin attenuates the oxidative-nitrosative stress in the liver of rats under long-term ethanol administration

Modulation of the AMP-activated protein kinase (AMPK) pathway activity is considered to be a promi­sing option in the development of approaches to chronic alcoholic hepatitis treatment. Phenformin, which is a biguanide, has been reported to increase AMPK activity. The aim of this work was to estimate the effect of phenformin as AMPK activator on the development of oxidative-nitrosative stress in the liver of rats under conditions of long-term ethanol administration. The experiments were performed on 24 male Wistar rats, divided into 4 groups: control; animals, which received phenformin hydrochloride orally at a dose of 10 mg/kg daily for 63 days; animals with a forced intermittent alcoholization for 5 days by intraperitoneal administration of 16.5% ethanol solution in 5% glucose at the rate of 4 ml/kg b.w. and subsequent transfer to 10% ethanol as the only source of drinking; animals with chronic alcohol hepatitis simulation and phenformin administration. Superoxide dismutase, catalase, NO synthase isoforms activity, superoxide anion radical production, concentration of malonic dialdehyde, peroxynitrite, nitrites, nitrosothiols concentration and oxidative modification of proteins (OMP) were estimated in liver homogenates. The increased production of oxygen and nitrogen active forms and OMP intensification in the liver of rats under long-term administration of ethanol was detected. Phenformin introduction under long-term ethanol administration was shown to limit the excess peroxynitrite formation and to prevent oxidative damage to rat liver proteins. Keywords: AMP-activated protein kinase., chronic alcoholic hepatitis, liver, oxidative and nitrosative stress, phenformin

Rhodamine 6G/Transition Metal Dichalcogenide Hybrid Nanoscrolls for Enhanced Optoelectronic Performance.

The low light absorption efficiency has seriously hindered the application of two-dimensional transition metal dichalcogenide (TMDC) nanosheets in the field of optoelectronic devices. Various approaches have been used to improve the performance of TMDC nanosheets. Preparation of one-dimensional TMDC nanoscrolls in combination with photoactive materials has been a promising method to improve their properties recently. In this work, we report a facile method to enhance the optoelectronic performance of TMDC nanoscrolls by wrapping the photoactive organic dye rhodamine (R6G) into them. After R6G molecules were deposited on monolayer TMDC nanosheets by the solution method, the R6G/MoS2 nanoscrolls with lengths up to hundreds of microns were prepared in a short time by dropping a mixture of ammonia and ethanol solution on the R6G/MoS2 nanosheets. The as-obtained R6G/MoS2 nanoscrolls were well characterized by optical microscopy, atomic force microscopy, Raman spectroscopy, and transmission electron microscopy to prove the encapsulation of R6G. There are multiple type II heterojunction interfaces in the R6G/MoS2 nanoscrolls, which can promote the generation of photo-induced carriers and the following electron-hole separation. The separated electrons were transported rapidly along the axial direction of the R6G/MoS2 nanoscrolls, which greatly improves the efficiency of light absorption and photoresponse. Under the irradiation of an incident 405 nm laser, the photoresponsivity, carrier mobility, external quantum efficiency, and detectivity of R6G/MoS2 nanoscrolls were enhanced to 66.07 A/W, 132.93 cm2V-1s-1, 20,261%, and 1.25 × 1012 cm·Hz1/2W-1, which are four orders of magnitude higher than those of monolayer MoS2 nanosheets. Our work indicates that the R6G/TMDC hybrid nanoscrolls could be promising materials for high-performance optoelectronic devices.

Low-Cost Preparation of Diamond Nanopillar Arrays Based on Polystyrene Spheres.

Diamond nanopillar arrays can enhance the fluorescence collection of diamond color centers, playing a crucial role in quantum communication and quantum sensing. In this paper, the preparation of diamond nanopillar arrays was realized by the processes of polystyrene (PS) sphere array film preparation, PS sphere etching shrinkage control, tilted magnetron sputtering of copper film, and oxygen plasma etching. Closely aligned PS sphere array films were prepared on the diamond surface by the gas-liquid interfacial method, and the effects of ethanol and dodecamethylacrylic acid solutions on the formation of the array films were discussed. Controllable reduction of PS sphere diameter is realized by the oxygen plasma etching process, and the changes of the PS sphere array film under the influence of etching power, bias power, and etching time are discussed. Copper antietching films were prepared at the top of arrayed PS spheres by the tilted magnetron sputtering method, and the antietching effect of copper films with different thicknesses was explored. Diamond nanopillar arrays were prepared by oxygen plasma etching, and the effects of etching under different process parameters were discussed. The prepared diamond nanopillars were in hexagonal close-rowed arrays with a spacing of 800 nm and an average diameter of 404 nm, and the spacing, diameter, and height could be parametrically regulated. Raman spectroscopy and photoluminescence spectroscopy detection revealed that the prepared diamond nanopillar array still maintains polycrystalline diamond properties, with only a small amount of the graphite phase appearing. Moreover, the prepared diamond nanopillar array can enhance the photoluminescence of diamond color centers by approximately 2 times. The fabrication method of diamond nanopillar array structures described in this article lays the foundation for quantum sensing technology based on diamond nanostructures.

Synthesis and Characterization of Ni based Metal Organic Framework for Enhancing the Removal of Typical Organic Dyes

In this report we present a simple synthesis of a nickel-based metal organic framework (MOF-Ni) at the room temperature using a solution of dimethylformamide (DMF), ethanol and distilled water. The MOF-Ni synthesized in various solvents displayed numerous different properties and advantages over other materials including easy synthesis procedure, good crystallinity, rigidity, and robust chemical stability. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermal gravimetric analysis (TGA) were employed to analyze the as-synthesized MOF-Ni. The as-obtained MOF-Ni was used to investigate its adsorption kinetics of red telon dye (RTL) molecules. The effects of time (30–270 min), initial RTL concentration (20–300 mg/L), adsorbent dose (2–50 mg), solution pH (2–12), and temperature (10–80 °C) were investigated. The pseudo-first order rate equation was able to provide the best description of the adsorption kinetics data in the studied time scale. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms, and the isotherm constants were also determined. Dye adsorption turned out to strongly depend on pH, and a low pH was found to increase the amount of adsorbed dyestuff. Compared with other samples, MOF-Ni synthesized in (DMF ​+ ​C2H5OH ​+ ​H2O) had a significantly enhanced adsorption ability for RTL dye. The MOF-Ni high adsorption capacity for RTL dye was attributed to the electrostatic attraction/repulsion phenomena. Moreover, MOF-Ni showed an improved stability at 370, 417, and 423 °C temperatures. The results obtained through our experiments suggested that our porous MOF-Ni microstructures synthesized in DMF ​+ ​C2H5OH ​+ ​H2O have potential applications for treating wastewaters containing RTL dyes.

Cosmetic Products with Potential Photoprotective Effects Based on Natural Compounds Extracted from Waste of the Winemaking Industry.

Grape marc is a by-product resulting from the winemaking industry that still contains beneficial compounds that can be valorized. Thus, we report here the possibility of using polyphenolic extracts of grape marc origin to obtain sun protection creams. The extractions were performed in ethanol and acetone solutions using pomace from different grape varieties (Merlot, Bläufrankisch, Fetească Neagră, Isabella) as a raw material. The obtained extracts were analyzed in order to determine the total phenolic content, the antioxidant activity, and the sun protection factor (SPF) via Mansur spectrophotometric assay. The best results were achieved using 70% ethanol in water as a solvent. The extracts with the highest potential photoprotective effects are from the Merlot variety (SPFspectrophotometric = 7.83 ± 0.76). The sunscreens were prepared using the 70% ethanolic extract of the Merlot variety evaporated to dryness, redissolved in either distilled water or ethanol. The SPF estimated in vitro via the COLIPA method showed values of 14.07 ± 1.50 and 11.46 ± 1.32 for the aqueous and ethanolic extracts, respectively, when working with a cream to polyphenolic extract a ratio of 1/1 (w/w). At the same time, the use of aqueous polyphenolic extracts ensures the better stability of creams compared with the ethanolic ones.

Purification and separation of caffeoyl spermidine derivatives from goji leaf tea with ion exchange resin and the mechanisms involved

Goji leaf (Lycium barbarum leaves, LBL) tea is a well-known beverage that has been developed and utilized for its numerous health benefits. Recently, we have successfully extracted four caffeoyl spermidines derivatives from LBL (LBLS), namely N-caffeoylputrescine, N-acetyl-N′-caffeoylputrescine, N1-dihydrocaffeoyl-N10-caffeoylspermidine and N1, N10-dicaffeoylspermidine. Given the diverse bioactivities exhibited by LBLS, our study aimed to develop a precise separation method and explore the possible purification mechanism. Firstly, the extraction process was optimized, followed by the selection of 001×7 resin for the enrichment and purification of LBLS from six resins. Subsequently, the adsorption mechanism was comprehensively examined using FT-IR, DSC, XRD, and XPS techniques. Additionally, investigations into the adsorption kinetics, isotherm models, and adsorption thermodynamics revealed the adsorption process of LBLS on 001×7 resin was spontaneous and exothermic, followed a monolayer adsorption mechanism, and conformed to the pseudo-second-order kinetic model and Langmuir model. The optimal procedure involved adsorbing a 25 mg/mL LBL extract onto a 3.5 BV (bed volume) at 2 BV/h, then eluting with an 8 % NaCl-55 % ethanol solution for 5 BV at the same rate. Finally, LBLS was separated using PHPLC to obtain monomer compounds. This process yields 1.57 %±0.1 % LBLS, and four monomers with purity range from 90.7 % to 100 % were obtained.

SCF-MMF based Michelson interferometer for ethanol multi-parameter measurements

A optical fiber Michelson interferometer (MI) for multi-parameter ethanol measurements is proposed and experimentally demonstrated. The sensor consists of a brief seven-core fiber (SCF) and a section of multimode fiber (MMF). With the SCF, multiple high-order modes are coupled into MMF, while the core fundamental mode and high-order modes are reflected back by the MMF end face and recoupled to the SMF by the SCF. When the surrounding ethanol changes, the reflection spectrum of the MI shift for the intermodal interference strongly integrates with the surrounding medium. Experimental results show that the sensor has an ethanol concentration sensitivity of −0.041 dB/% over the range of 0–90 %. The level sensitivities are −0.0795 nm/mm and −0.1052 nm/mm in the 0–5 mm range for 5 % and 10 % ethanol solutions, respectively, while in the 5–20 mm range, the sensitivities are −0.2773 nm/mm and −0.2243 nm/mm, respectively. Moreover, the volatilization time and volatilization stability are tested under different concentrations of ethanol, and the volatilization sensitivity is 0.071 dB/% in the range of 0–60 %. Response and recovery time of 1.008 s and 0.514 s for 15 % ethanol volatilization molecules is achieved. This MI has advantages of compact structure, easy fabrication, good stability and dominant ability to achieve multi-parameter ethanol measurement via reflective operation.

Highly Sensitive Balloon-like Fiber Interferometer Based on Ethanol Coated for Temperature Measurement.

A highly sensitivity balloon-like fiber interferometer based on ethanol coating is presented in this paper. The Mach-Zehnder interferometer is formed by bending a single-mode fiber to a balloon-like structure and nested in the Teflon tube. Then, an ethanol solution was filled into the tube of the balloon-like fiber interferometer by the capillary effect. Due to the high sensitivity of the refractive index (RI) of ethanol solutions to temperature, when the external temperature varies, the optical path difference changes. The change in temperature can be detected by the shift in the interference spectrum. Limited by the size of the balloon-like structure, three kinds of these structures with different sensitive lengths were prepared to select the best parameters. The sensitive lengths were 10, 15 and 20 mm, respectively, and the RI detection performance of each structure in 10~26% NaCl solutions was investigated experimentally. The results show that when the sensitive length is 20 mm, the RI sensitivity of the sensor is the highest, which is 212.88 nm/RIU. Ultimately, the sensitive length filled with ethanol is 20 mm. The experimental results show that the temperature sensitivity of the structure is 1.145 nm/°C in the range of 28.1 °C~35 °C, which is 10.3 times higher than that of an unfilled balloon-like structure (0.111 nm/°C). The system has the advantages of low cost and easy fabrication, which can potentially be used in high-precision temperature monitoring processes.

Mechanical Properties of Alkasite Material with Different Curing Modes and Simulated Aging Conditions.

This study aimed to evaluate the micro-mechanical and macro-mechanical properties of self-cured and light-cured alkasite and to investigate how accelerated degradation in acidic, alkaline, and ethanol solutions affects the macro-mechanical properties of self-cured and light-cured alkasite. The specimens of the alkasite material (Cention Forte, Ivoclar Vivadent) were prepared according to the following three curing modes: (1) light-cured immediately, (2) light-cured after a 5-min delay, and (3) self-cured. Microhardness was tested before and after immersion in absolute ethanol to indirectly determine crosslink density, while flexural strength and flexural modulus were measured using a three-point bending test after accelerated aging in the following solutions: (1) lactic acid solution (pH = 4.0), (2) NaOH solution (pH = 13.0), (3) phosphate-buffered saline solution (pH = 7.4), and (4) 75% ethanol solution. The data were statistically analyzed using a two-way ANOVA and Tukey post hoc test. The results showed that the microhardness, flexural strength, and flexural modulus were significantly lower in self-cured specimens compared to light-cured specimens. A 5-min delay between the extrusion of the material from the capsule and light curing had no significant effect on any of the measured properties. A significant effect of the accelerated aging solutions on macro-mechanical properties was observed, with ethanol and alkaline solutions having a particularly detrimental effect. In conclusion, light curing was preferable to self-curing, as it resulted in significantly better micro- and macro-mechanical properties, while a 5-min delay between mixing the capsule and light curing had no negative effects.

Catalytic Activity and Mechanical Stability of ZIFs‐Derived CoCeOx/Cordierite Monolithic Catalysts

AbstractBimetallic oxide catalysts derived from zeolitic imidazolate frameworks (ZIFs) have good catalytic oxidation activity, but their application is limited because the powder is not conducive to industrial production. In this study, CoCeOx/cordierite monolithic catalysts derived from ZIFs were prepared by a simple impregnation method. Firstly, a phase transition of Co‐ZIF was induced in ethanol solution by adding excessive Ce(NO3)3. Subsequently, tannic acid (TA) was used to chelate excess metal on the surface to expose more active sites. Meanwhile, TA staying on the surface of the precursor could also prevent the accumulation of Ce at high temperatures. After the activity test, CoCeOx/cordierite showed excellent activity for the catalytic oxidation of o‐xylene with a T90 of 295 °C. The mechanical stability of the catalyst was also tested by ultrasonic vibration method. In addition, we investigated the influence of factors such as impregnation cycles and TA treatment time on the physical and chemical properties. This paper provides a new idea for preparing monolithic catalysts derived from ZIFs.

Sol-Gel Synthesis of Silica-Poly (Vinylpyrrolidone) Hybrids with Prooxidant Activity and Antibacterial Properties.

The present work deals with the sol-gel synthesis of silica-poly (vinylpyrrolidone) hybrid materials. The nanohybrids (Si-PVP) have been prepared using an acidic catalyst at ambient temperature. Tetramethyl ortosilane (TMOS) was used as a silica precursor. Poly (vinylpyrrolidone) (PVP) was introduced into the reaction mixture as a solution in ethanol with a concentration of 20%. The XRD established that the as-prepared material is amorphous. The IR and 29Si MAS NMR spectra proved the formation of a polymerized silica network as well as the hydrogen bonding interactions between the silica matrix and OH hydrogens of the silanol groups. The TEM showed spherical particle formation along with increased agglomeration tendency. The efficacy of SiO2/PVP nanoparticles as a potential antimicrobial agent against a wide range of bacteria was evaluated as bacteriostatic, using agar diffusion and spot tests. Combined effects of hybrid nanomaterial and antibiotics could significantly reduce the bactericidal concentrations of both the antibiotic and the particles, and they could also eliminate the antibiotic resistance of the pathogen. The registered prooxidant activity of the newly synthesized material was confirmative and explicatory for the antibacterial properties of the tested substance and its synergetic combination with antibiotics. The effect of new hybrid material on Crustacea Daphnia magna was also estimated as harmless under concentration of 0.1 mg/mL.

Bottom-Up Assembling Hierarchical Enamel-Like Bulk Materials with Excellent Optical and Mechanical Properties for Tooth Restoration.

Enamel has good optical and mechanical properties because of its multiscale hierarchical structure. Biomimetic construction of enamel-like 3D bulk materials at nano-, micro-, mesh- and macro-levels is a challenge. A novel facile, cost-effective, and easy large-scale bottom-up assembly strategy to align 1D hydroxyapatite (HA) nanowires bundles to 3D hierarchical enamel structure with the nanowires bundles layer-by-layer interweaving orientation, is reported. In the strategy, the surface of oleate templated ultralong HA nanowires with a large aspect ratio is functionalized with amphiphilic 10-methacryloyloxydecyl dihydrogen phosphate (MDP). Furtherly, the MDP functionalized HA nanowire bundles are assembled layer-by-layer with oriented fibers in a single layer and cross-locked between layers at a certain angle at mesoscale and macroscale in the viscous bisphenol A-glycidyl methacrylate (Bis-GMA) ethanol solution by shear force induced by simple agitation and high-speed centrifugation. Finally, the excessive Bis-GMA and ethanol are removed, and (Bis-GMA)-(MDP-HA nanowire bundle) matrix is densely packed under hot pressing and polymerized to form bulk enamel-like materials. The composite has superior optical properties and comparable comprehensive mechanic performances through a combination of strength, hardness, toughness, and friction. This method may open new avenues for controlling the nanowires assembly to develop hierarchical nanomaterials with superior properties for many different applications.

Polyoxometalates decoration combining with solvent activation for enhanced separation performance of nanofiltration membrane

Nanofiltraion (NF) membranes are promising candidates for overcoming critical global issues of access to clean water. However, current NF membranes are hampered by the trade-off between the water permeability and selectivity as well as the fouling propensity. In this work, a facile surface decoration simultaneously combined with solvent activation strategy was adopted for the NF membrane modification via simply immersing membrane into the polyoxometalates (POMs) ethanol solution. The introduction of POMs by coordination assembly increases the membrane hydrophilic and electronegativity, and the ethanol loosens the membrane selective layer, leading to the enhanced membrane perm-selectivity and anti-organic fouling property. The permeance and Na2SO4 rejection of the optimized modified NF membrane are 14.90 ± 0.21 LMH/bar and 99.20 ± 0.38 %, which are ∼20 % and more than 3 % increments compared with those of the control membrane, respectively. The modified NF also reveals a lower permeance decline as well as a higher flux recovery toward both positive and negative charged foulants. In addition, benefiting from the biocidal activity of the POMs, the membrane anti-biofouling property is also significantly improved under an extremely low loading of POMs. More importantly, the chemical stability of the modified NF membrane is reinforced due to the protection from the introduced POMs. Our work contributes to revitalizing the prospect of developing NF membranes with excellent filtration performance and antifouling property.

Direct synthesis of undoped/doped SrTiO3 nanoparticles from solution

Directly crystallizing strontium titanate (SrTiO3) nanoparticles from a solution near room temperature poses a challenge due to Ti ions easily form colloids and result in amorphous products. It is also difficult to ensure the uniform incorporation of the dopants into the lattice during synthesis of doped samples. This study successfully achieved this task using the direct synthesis from solution (DSS) method. Both undoped SrTiO3 nanoparticles and Fe-doped one were synthesized in an ethanol solution at the temperatures ranging from 60 to 80 °C, resulting in homogeneous grains with an average size of approximately 15 nm. Despite the solubility limit of Fe3+ in bulk SrTiO3 being around 2.5 %, we successfully synthesized Fe-doped SrTiO3 nanocrystals with high doping level even at a dose of 10 %.The tribocatalytic performance of both undoped and Fe-doped SrTiO3 nanoparticles was evaluated for methylene blue degradation in a solution. Undoped SrTiO3 nanoparticles showed similar catalytic performance to P25. In contrast, Fe-doped SrTiO3 nanoparticles exhibited much higher catalytic performance. This enhanced catalytic performance is attributed to the presence of oxygen vacancies, which are introduced by doping Fe3+ into the SrTiO3 lattice to substitute the Ti ion.

Novel polydopamine-based composites with adjustable antioxidant activity

It is obtained here that dopamine and quercetin, not easily miscible compounds, can form stable quercetin – polydopamine (Q:PDA) composite systems under special conditions: oxidative polymerization of dopamine in the presence of quercetin in mixed water/ethanol solution at both, acidic and alkaline pH, by using NaIO4 as oxidant. The structure of the Q:PDA composites in bulk and as coating layers on SiO2 nanoparticles has been characterized by solid-state NMR spectroscopy, which directly confirms the incorporation of quercetin in the PDA matrix. Indirectly, it was also proved by HPTLC by monitoring quercetin released during Q:PDA disassembling in strongly acidic 0.1 M HCl solution. The morphology of Q:PDA coating layers has been characterized by AFM on glass substrates. It was found that, compared to PDA alone, layer thickness is increased in the presence of quercetin, reaching the highest value of about 190 nm for 1:1 quercetin/dopamine relative concentration, at pH 5.5 and 24 h deposition time. Sine quercetin is one of the most widely consumed natural antioxidant, and PDA has been reported with interesting antioxidant activity, the free radical scavenging properties of the Q:PDA composites was investigated. The free radicals bleaching activity was found dependent on the specific Q:PDA synthesis/deposition conditions, which might be of interest in biomedical applications that require adjustable antioxidant activity.

Impact of annealing treatment on adlayer structures of terphenylmethanethiol self-assembled monolayers on Au(111)

The scanning tunneling microscopy (STM) technique was employed to investigate the adlayer structure and morphology of Self-assembled monolayers (SAMs) fabricated from terphenylmethanethiol (TP1) molecules on Au(111) by preparing from an ethanolic solution at room temperature and subsequently annealed at various temperatures, reaching up to 468 K. Upon heat treatment, the TP1 adlayer exhibited a sequence of distinct structural phases characterized by varying molecular arrangements, namely α, β, γ, δ, ε, σ, and θ, emerging successively for both the as-prepared and annealed samples. The progressive transformation from α→β→ γ→δ→ε→σ→α→θ phases, driven by escalating annealing temperatures, entailed a gradual decrease in molecular packing density until the transition from γ→δ, followed by a subsequent increase leading to the formation of the most densely packed molecular network with molecules standing almost upright, referred to as the α phase, which is the same phase observed for non-heat-treated films. Interestingly, the desorption process for the annealed SAMs occurred from the densest packing TP1 molecular structure of the α phase, contrary to those of biphenyl-based organothiol and n-alkanethiol SAMs where desorption takes place from lying-down striped phases. Almost all TP1 molecules were desorbed at an annealing temperature of 468 K, leading to a significant alteration in the surface structure. During the annealing process, our results showed that the gold surface underwent remarkable changes, including the disappearance of the vacancy islands and the emergence of surface cracks in the form of trenches, along with the formation of rounded monoatomic gold islands with a densely packed α phase.

Alternative green solvents associated with ultrasound-assisted extraction: A green chemistry approach for the extraction of carotenoids and chlorophylls from microalgae

This study proposes a method for the ultrasonic extraction of carotenoids and chlorophyll from Scenedesmus obliquus and Arthrospira platensis microalgae with green solvents. Ethanol and ethanolic solutions of ionic liquids were tested with a variety of extraction parameters, including number of extractions, time of extraction, and solid–liquid ratio R(S/L), to determine the optimal conditions. After selecting the most effective green solvent (ethanol), the process conditions were established: R(S/L) of 1:10, three extraction cycles at 3 min each), giving an extraction yield of 2602.36 and 764.21 μgcarotenoids.gdried biomass−1; and 22.01 and 5.81 mgchlorophyll.gdried biomass−1 in S. obliquus and A. platensis, respectively. The carotenoid and chlorophyll extracts obtained using ethanol were shown to be potent scavengers of peroxyl radical, being 5.94 to 26.08 times more potent α-tocopherol. These findings pave the way for a green strategy for valorizing microalgal biocompounds through efficient and environmentally friendly technological processes.

Separation of bufadienolides from Helleborus thibetanus Franch. by a combination approach involving macroporous resin column chromatography and gradient countercurrent chromatography.

In this study, a combination approach involving macroporous resin (MR) column chromatography and gradient countercurrent chromatography (CCC) was employed to enrich and purify bufadienolides from the roots and rhizomes of Helleborus thibetanus Franch. Initially, a D101 MR-packed column chromatography was utilized for fractionation and enrichment of the bufadienolides, which were effectively eluted from the column using a 60% ethanol solution. CCC was subsequently introduced to separate the enriched product using the ethyl acetate/n-butanol/water (EBuWat, 4:1:5, v/v) and EBuWat (5:0:5, v/v) solvent systems in a gradient elution mode. As results, five bufadienolides, including 6.1mg of hellebrigenin-3-O-β-D-glucoside (1), 2.2mg of tigencaoside A (2), 8.3mg of deglucohellebrin (3), 3.5mg of 14 β-hydroxy-3β-[β-D-glucopyranosyl-(1→6)-(β-D-glucopyranosyl)oxy]-5α-bufa-20,22-dienolide (4), and 3.0mg of 14β-hydroxy-3β-[(β-D-glucopyranosyl)oxy]-5α-bufa-20,22-dienolide (5), were effectively separated from 300mg of the enriched product. The respective high-performance liquid chromatography purities were as follows: 95.2%, 75.8%, 85.7%, 82.3%, and 92.8%. This study provides valuable insights for the efficient enrichment and separation of bufadienolides from Helleborus thibetanus Franch.