Search

The prevention of drying-induced cracking is crucial in maintaining the mechanical integrity and functionality of colloidal deposits and coatings. Despite exploring various approaches, controlling drying-induced cracking remains a subject of great scientific interest and practical importance. By introducing chain-like particles composed of the same material and with comparable size into commonly used colloidal suspensions of spherical silica nanoparticles, we can significantly reduce the cracks formed in dried particle deposits and achieve a fivefold increase in the critical cracking thickness of colloidal silica coatings. The mechanism underlying the crack suppression is attributed to the increased porosity and pore sizes in dried particle deposits containing chain-like particle, which essentially leads to reduction in internal stresses developed during the drying process. Meanwhile, the nanoindentation measurements reveal that colloidal deposits with chain-like particles exhibit a smaller reduction in hardness compared to those reported using other cracking suppression approaches. This work demonstrates a promising technique for preparing colloidal coatings with enhanced crack resistance while maintaining desirable mechanical properties. [ABSTRACT FROM AUTHOR]

The preparation of fused silica glass with microstructural patterns has attracted considerable interest, and the process chain of using nano-silica powders mixed with organic polymers to prepare composites for molding, degreasing, and sintering provides a good solution. However, the potential negative effects of organic residues cannot be avoided. In this study, a pattern stencil replication method with silica gel using high-purity quartz fibers as reinforcement is proposed for preparing micropatterned fused silica glass. The microscopic morphology and mechanical properties before and after silica gel drying and the optical properties of fused silica glass obtained by sintering were evaluated via transmission electron microscopy), three-point bending strength test, scanning electron microscopy, X-ray diffraction spectrum analysis, ultraviolet–visible and infrared measurements. The results showed that quartz fiber as a reinforcer could shorten the drying time of the gel and did not degrade the quality of the fused silica glass obtained by sintering. Laser confocal test results showed that microlens arrays were generated by template replication, demonstrating the feasibility of molding fused silica lens arrays with small feature sizes and providing new ideas for the preparation of bulk fused silica glass or micropatterned glass. [ABSTRACT FROM AUTHOR]

The degree of ease of use and the readily observable signals associated with the detection process are critical factors in determining the success of a detection strategy. Considering this perspective, we report the detection of phosgene by modulating the photophysical characteristics of a molecular probe, Xanth-NH2. The probe is non-emissive in nature, but the presence of phosgene facilitates the probe's radiative decay, which enables phosgene detection via fluorescence turn-on change. The fluorescence changes vary linearly with phosgene concentration, contributing to a nanomolar level detection limit for phosgene. Additionally, under a controlled set of conditions, the half-time for the reaction of Xanth-NH2 with phosgene is 68 s. To demonstrate the potential application of Xanth-NH2, probe-loaded paper strips or silica gel were developed as an economic tool for the detection of phosgene in vapor or solution phase. Phosgene detection has been accomplished with a portable UV light source and a smartphone to track minute changes during the detection event. [ABSTRACT FROM AUTHOR]

This document provides detailed information on the synthesis and characterization of several compounds, including their chemical composition, yield, melting point, and spectroscopic data. The authors acknowledge financial support from the Research Council of the Islamic Azad University, Rasht Branch, and no conflicts of interest were reported. [Extracted from the article]

Shear thickening fluids (STF) represent stabilized and concentrated colloidal suspensions, wherein hard nanoparticles are dispersed within a liquid medium (polymer). Under the influence of impact forces, they exhibit non-Newtonian behavior, effectively dissipating energy through shear thickening. The optimization of the dispersion medium's viscosity is critical, as it not only fosters shear thickening but also facilitates proper particle dispersion. This study investigates the impact of graphene oxide (GO) as an additive in STFs, analyzing both static and dynamic rheological properties. STFs were formulated using colloidal silica particles (600 nm) and polyethylene glycol (PEG-200), with varied concentrations of GO particles (0.12–0.5 % w/W). The systems underwent comprehensive analysis concerning steady-state and dynamic-state rheological behavior under diverse conditions. The findings reveal that the inclusion of GO augments both static and dynamic rheological properties, reaching an apex at an optimal concentration of 0.36 % w/W. GO functions as a network builder within the STF, interacting with the existing particle network to create a more robust and interconnected structure. These enhanced properties underscore the potential of the synthesized STF for applications requiring impact resistance. [ABSTRACT FROM AUTHOR]

An inexpensive membrane with high proton conductivity and high fuel cell performance, which can be an alternative to Nafion for PEMFC (Proton exchange membrane fuel cell), will overcome the obstacle to widespread commercialization of fuel cells due to high cost. For this purpose, SPEEK (sulfonated polyether ether ketone)-PVA (polyvinyl alcohol) blend membranes with colloidal silica additives were synthesized in this study. Ludox AS-40 was used as the colloidal silica source and the blend membrane was prepared by solution casting method. Water uptake capacity, swelling property, size change, dynamic mechanical analysis, ion exchange capacity, AC impedance analysis, hydrolytic and oxidative stability experiments of the synthesized Ludox additives blend membranes for fuel cell application were carried out, and the membranes were also characterized by FTIR (Fourier transform infrared) analysis. While the water uptake capacities of SPEEK/PVA membranes containing 1% Ludox, 5% Ludox, and 10% Ludox at room temperature were found to be 14.08%, 14.84%, and 16.6%, respectively, the water uptake capacities at 80oC increased to 14.73%, 15.17%, and 17.11%. The proton conductivities of 1% Ludox, 5% Ludox and 10% Ludox doped SPEEK/PVA membranes at 80oC were 0.25 S/cm, 0.56 S/cm, and 0.65 S/cm, respectively. Similarly, ion exchange capacities were determined to be 1.41 meq/g, 1.63 meq/g, and 1.71 meq/g, respectively. All Ludox-added membranes exhibited excellent hydrolytic stability, retaining approximately 88% of their mass after 650 h. In addition, in oxidative stability experiments carried out in 4 ppm Fe+ 2 at 80oC, the 10% Ludox-added membrane exhibited the highest weight loss of 88.8% at the end of 24 h, while the 5% Ludox-additive membrane retained 91.6% of its total weight. Considering the proton conductivity and longevity tests of the synthesized membranes, they are thought to be promising structures. [ABSTRACT FROM AUTHOR]

AbstractPrecise, accurate, and sensitive high performance thin layer chromatographic method has been developed and validated for simultaneous determination of efonidipine hydrochloride (EFD) and telmisartan (TEL) in a tablet dosage form which is used in treatment of hypertension. The proposed method used aluminum plates pre-coated with silica gel 60 F254 as a stationary phase and n-butanol: toluene: acetic acid (3:7:0.2, v/v/v) as a mobile phase for separation purpose. Compact spots of TEL and EFD were obtained at Rf 0.73 and 0.37, respectively. Densitometric detection was carried out at 299 nm in UV. Linear responses were shown by the detector over the range of 200–1200 ng/band for both drugs. The proposed method was validated as per ICH guidelines. The method was successfully applied for estimation of both drugs in tablet formulations. Forced degradation study was carried and efonidipine was found to be susceptible to base hydrolysis and oxidative stress degradation while TEL was stable in acid-base hydrolysis, oxidative stress, dry heat and photo stability testing conditions. The developed method can be used for the analysis of stability samples. Greenness assessment of developed method was performed using AGREE software. The method was found to be greener having greenness score of 0.69. [ABSTRACT FROM AUTHOR]

Due to unique structural characteristics and chiral environment, β‐cyclodextrin (β‐CD) has a strong chiral separation ability. 4‐Chlorophenyl isocyanate (4CPI) also plays an important role in separating chiral drugs. In this paper, a chiral stationary phase: 4‐CPI‐β‐CD stationary phase (4CPI‐β‐CD@PMMA) was designed and prepared. Polymethyl methacrylate (PMMA) microspheres with uniform particle size and good monodispersity were prepared by modified seed polymerization and seed expansion methods. Using diazo resin as a coupling agent, PMMA microspheres were connected with 4CPI‐β‐CD to prepare a stationary phase with chiral recognition ability. PMMA microspheres and 4CPI‐β‐CD were also characterized. Compared with the traditional silica gel column, PMMA microspheres have higher preparation efficiency, better monodispersity, and better mechanical properties as chromatographic fillers. Finally, the chiral separation of ketoprofen was carried out by reversed‐phase high‐performance liquid chromatography, and the separation conditions were optimized. This paper is a good idea for the preparation of the chiral stationary phase. [ABSTRACT FROM AUTHOR]

A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) -LC-MS/MS method was developed for the determination of hexachlorophene in fruits and vegetables. Samples were extracted by acetonitrile and then salted with an acetate buffer system. Extractants neutral alumina (Al-N), strong cation exchange silica gel bonded adsorbent (SCX) and graphitized carbon black (GCB) were used for sample purification. The method demonstrates excellent accuracy and reproducibility. Under optimized conditions, the correlation coefficients of hexachlorophene were higher than 0.995 in the range of 0.5–20 ng/mL. The limit of quantification (LOQ) was 2.0 μg/kg. The average recoveries, assessed at three spiked levels (2.0, 4.0, and 20.0μg/kg) across various matrices including cabbage, celery, tomato, eggplant, potato, radish, cowpea, chives, apple, peach, grape, citrus, bitter melon, banana and hami melon ranged from 72.0 to 100.5% with relative standard deviations from 3.2 to 9.8% (n = 6). [ABSTRACT FROM AUTHOR]

Sulfonamides are not only widely applied in clinics but also highly valued in animal husbandry. Recently, it has become common for sulfonamide residues to exceed the standard limits in food, which can affect human health. Current regulations limit these residues. Therefore, we constructed a new limit test method to rapidly determine the levels of sulfonamide residues. Six sulfonamides were detected using the latest method called TLC-SERS, namely, sulfamethasone (A), sulfamethazine (B), sulfadoxine (C), sulfamethoxydiazine (D), sulfamethoxazole (E), and sulfathiazole (F). The optimal conditions for SERS detection were investigated for these six drugs, and the separation effects of different TLC spreaders on them were compared. Then, we successfully established a separation system using dichloromethane–methanol–ammonia in a ratio of 5:1:0.25 (v/v/v), which provided good separation effects on the six drugs. The residues were preliminarily separated via TLC. A silver sol solution was added to the spot on the silica gel G plate at the corresponding specific shift values, and SERS detection was performed. The sample solution was placed on the spot under a 532 nm laser, and the SERS spectrum was collected and analyzed for the six sulfonamides. The results showed obvious variations in the SERS spectrum among the six sulfonamides, with the LODs being 12.5, 6.4, 6.3, 7.1, 18.8, and 6.2 ng/mL from A to F, respectively, and an RSD of <3.0%. Within 48 h, the SERS signal for each sulfonamide drug was kept stable, with an RSD of <3.0%. The detection results of 20 samples using the TLC-SERS method were consistent with those obtained by UPLC-MS/MS. The established TLC-SERS method is simple and fast, providing a useful reference for the rapid detection of residue limits in food. [ABSTRACT FROM AUTHOR]

In this study, core/shell‐structured mesoporous hybrid silica gel particles were synthesized for the selective adsorption of hyaluronic acid. A non‐ionic amphiphilic polymer core consisting of poly(methyl methacrylate) and poly(ethylene glycol) blocks were coated with SiO2 using the Stöber method in the presence of non‐ionic and cationic surfactants to obtain mesoporous core‐shell silica particles. The surface of silica particles was functionalized through modification of L‐aspartic acid to improve their affinity against the targeted analyte, hyaluronic acid. Physico‐chemical methods including Fourier transform infrared spectroscopy, thermal gravimetric analysis, zeta‐size measurements, and transmission‐ and scanning‐electron microscopies were utilized to evaluate the properties of core‐silica particles. The surface functionalized core/shell particles have an average size of 254.7 (±33.1) nm as confirmed by TEM analysis. The hyaluronic acid adsorption performance of the modified core‐shell silica particles was optimized through varying pH, concentration, temperature, and contact time parameters. Thermodynamic parameters were estimated by applying adsorption isotherm and kinetics models to assess the favorability of the adsorption process. The models revealed that the hyaluronic acid adsorption processes follow monolayer adsorption (Langmuir model) and chemisorption (pseudo‐second‐order kinetics) processes. [ABSTRACT FROM AUTHOR]

In the oxidative dehydrogenation of propane in the presence of CO2, supported monometallic M/SiO2 (M = Zn, Cu) and bimetallic MCr/SiO2 oxide catalytic systems were studied in the temperature range 600–700°C. The catalytic systems were characterized by TG–DTG–DTA, SEM–EDX, and UV–Vis diffuse reflectance spectroscopy. It was revealed that the addition of a second metal leads to a decrease in propane conversion to 32%, while the selectivity for propylene increases to 75% on the 3Zn3Cr/SiO2 sample at 600°C. [ABSTRACT FROM AUTHOR]

Inorganic–inorganic self‐organized composite architectures resulting from the chemical coupling of alkaline‐earth carbonate and polymeric silica are a promising alternative to organic‐based hybrid bio‐mimetic systems for developing innovative multi‐functional materials. Although the importance of pH in the generation of these structures reminiscent of primitive living organisms (and for this called biomorphs) is widely acknowledged, the effect of pH is generally investigated on the basis of starting pH value. This approach inadvertently neglects the important spatial and temporal pH gradients associated with biomorph nucleation and growth. A deep understanding of the role of pH on morphogenesis requires the ability to detect locally the pH in real‐time with a non‐invasive technique and correlate pH to the different stages of biomorphic growth. This aim is achieved by combining optical and fluorescence imaging. An accurately selected pH probe suitable for ratiometric pH measurement in the silica gel is exploited during a typical counter‐diffusion experiment. The results are compared with computer simulation of the synthesis of biomorphs by counter‐diffusion experiments. The results demonstrate the existence of two main morphogenetic regimes. Interestingly, the morphogenetic process controlling the complex shaping of biomorphs results to be independent of the silica speciation. [ABSTRACT FROM AUTHOR]

As a result of the adsorption of copolymer 5-(4-nitro)phenylazo-8-methacryloxyquinoline with methyl methacrylate on the surface of mesoporous silica gel, a new polymer-inorganic composite material was obtained. Based on the comparison of the sorption capacity of the synthesized composite and the composite based on silica gel with in situ immobilized poly-5-(4-nitro)phenylazo-8-methacryloxyquinoline, it was concluded that the method of in situ immobilization of complex-forming polymers on the surface of silica gel is more effective compared to their physical adsorption. [ABSTRACT FROM AUTHOR]

As global temperatures rise, droughts are becoming more frequent and severe. To predict how drought might affect plant communities, ecologists have traditionally designed drought experiments with controlled watering regimes and rainout shelters. Both treatments have proven effective for simulating soil drought. However, neither are designed to directly modify atmospheric drought. Here, we detail the efficacy of a silica gel atmospheric drought treatment in outdoor mesocosms with and without a co‐occurring soil drought treatment. At California State University, Los Angeles, we monitored relative humidity, temperature, and vapor pressure deficit every 10 min for 5 months in bare‐ground, open‐top mesocosms treated with soil drought (reduced watering) and/or atmospheric drought (silica dehumidification packets suspended 12 cm above soil). We found that silica packets dehumidified these mesocosm microclimates most effectively (−5% RH) when combined with reduced soil water, regardless of the ambient humidity levels of the surrounding air. Further, packets increased microclimate vapor pressure deficit most effectively (+0.4 kPa) when combined with reduced soil water and ambient air temperatures above 20°C. Finally, packets simulated atmospheric drought most consistently when replaced within 3 days of deployment. Our results demonstrate the use of silica packets as effective dehumidification agents in outdoor drought experiments. We emphasize that incorporating atmospheric drought in existing soil drought experiments can improve our understandings of the ecological impacts of drought. [ABSTRACT FROM AUTHOR]

This work aims at developing a customized ammoxidation catalyst through optimizing the metal oxide content in CrVO4/SiO2 catalysts. Various amounts of Cr–V–O with 1:1 molar ratio of Cr/V were successfully loaded on SiO2 via spray-drying method with colloidal silica as the binder. Polarized light microscope illustrated that the CrVO4/SiO2 particles presented as well dispersed microspheres in the microsize (20–80 μm). X-ray diffraction spectra confirmed the formation of monoclinic CrVO4 phase wherein the metal oxide content was ranged from 30 to 70 weight percent. FT-IR spectra indicated that the introduction of metal oxide had no obvious effects on the skeletal structure of SiO2. X-ray photoelectron spectroscopy analysis revealed that the valence state of V and Cr was hardly affected with increasing the metal oxide content. Performances of the obtained CrVO4/SiO2 catalysts with different metal oxide contents were investigated via the ammoxidation of a model compound, namely para-chlorotoluene (PCT) to para-chlorobenzonitrile (PCBN). A maximum conversion of 99.6% of PCT and 86.5% yield and 86.8% selectivity to PCBN have been obtained over the CrVO4/SiO2 catalyst with 60% weight of metal oxides at a temperature of 410 °C, n(PCT):n(NH3):n(air) = 1:3:15 and reaction load = 0.13 g/gCat·h. In addition, this catalyst was efficient and selective toward ammoxidation reactions of toluene, ortho- and meta-chlorotoluenes. [ABSTRACT FROM AUTHOR]

The coexistence of different foulant compositions in the feed water of reverse osmosis (RO) systems causes serious complications in the fouling process of the membranes. Hence, in this technical research, the phenomenon of combined inorganic (gypsum)-colloidal (silica particles) fouling (inorganic-colloidal fouling) of brackish water RO (BWRO) process was studied in the lab-scale experiments. Moreover, the effect of the presence of air micro–nano bubbles (AMNBs) in the feed water; as a new practical method for control of membrane fouling, was investigated on this phenomenon. For this purpose, a suspension with the potential of inorganic scaling [calcium sulfate, Saturation index (SI)=0.96 ] and colloidal fouling (colloidal silica, 50 mg/L) was used to form the inorganic and colloidal foulings (simultaneously) on the membrane surface during the inorganic-colloidal fouling process. All experiments were performed twice, once in the absence and once in the presence of AMNBs. Finally, the results of this research were compared with the results of the inorganic and colloidal fouling studies. Based on the results, the inorganic-colloidal fouling formed a dense and compact fouling layer on the membrane surface, which severely reduced the permeate flux (76.3%) and salt rejection (4%). The amount of decrease of these two parameters in inorganic-colloidal fouling was much higher than each of individual inorganic and colloidal foulings. In the presence of AMNBs, both types of inorganic and colloidal foulings greatly reduced and the major portion of inorganic-colloidal fouling was related to the colloidal fouling. Thus, a significant decline was observed in adverse effects of inorganic-colloidal fouling on the membrane performance and the permeate flux and salt rejection decreased by 18.5% and about 1%, respectively. The results of this study could introduce the micro–nano bubbles (MNBs) technology as an effective method to inhibit the inorganic-colloidal fouling in RO systems. Practical Applications: Today, reverse osmosis processes are known as efficient technologies for supplying drinking water from brackish and sea water resources due to their high ability to remove various compounds. The separated compounds from the water accumulate near the membrane surface and consequently deposit on it and/or inside its pores. This phenomenon is called membrane fouling and has adverse effects on the performance of reverse osmosis processes. Water resources usually have different types of pollutants that simultaneous presence of them can intensify the membrane fouling process. Gypsum scaling and colloidal silica fouling are two major common types of reverse osmosis membrane fouling. Therefore, in this research, the effects of the inorganic-colloidal fouling were studied on the performance of a commercial brackish water reverse osmosis membrane, in presence and absence of air micro–nano bubbles. The results showed that the combined fouling formed a complex fouling layer on the membrane surface in absence of air micro–nano bubbles. In real-scale reverse osmosis process, this layer can severely reduce the membrane permeate flux and salt rejection which result to increase in the operational and maintenance costs. Alternatively, the presence of air micro–nano bubbles in the reverse osmosis feed flow could limit both inorganic and colloidal foulings and their synergetic effects on each other. [ABSTRACT FROM AUTHOR]

Adsorption chiller dynamics and its effect on the performance are greatly influenced by the adsorbent particle size because they govern both the micro (intra-particle) and macro (inter-particle) heat and mass transfer resistances within the adsorber bed. The net effect of adsorbent particle size and shape on the overall cooling system performance is addressed here. Initial CFD analysis of columnar adsorber bed with silica gel + water as the working pair, assuming uniform spherical adsorbent, showed increased uptake capacity with smaller sized (0.23 mm radius) particles over bigger sized (0.8 mm radius) ones despite smaller vapor penetration depth of the former. Subsequently, the effect of adsorbent particle size and shape on the overall cooling system performance is investigated experimentally in a single-stage one-bed mode for RD 2060 (0.8 mm radius) and RD 3070 (0.23 mm radius) silica gel specimens. Though the smaller size of RD 3070 is favourable for the adsorption kinetics at the particle level, its non-spherical shape and highly non-uniform size distribution resulted in significantly lower permeability and thermal diffusivity of the packed adsorber bed, thus hindering the cyclic steady state throughput. For the same operating conditions, RD 2060 and RD 3070 yield a cooling capacity (CC) of 107 W and 22 W, respectively. Further, the coefficient of performance (COP) drops by 73% in the case of RD 3070. The present study indicates that the adsorber bed design must consider both the adsorbent size and shape, in addition to other system operational parameters to enhance performance indicators. [ABSTRACT FROM AUTHOR]

Tyrosol is a principle phenolic compound present in olive oil and wine with great pharmacological potentials due to its strong antioxidant property. Its application can be highly extended by increasing its lipophilicity through esterification. In this study, tyrosol esters were synthesized by enzymatic transesterification of tyrosol with vinyl esters, with a commercial lipase from Novozymes (Novozym 435, Candida antarctica lipase B (CALB) immobilized on macroporous acrylic resin beads) as the catalyst, both in organic solvents and in ionic liquids. Methyl tert-butyl ether (MTBE) was the best solvent, offering complete conversions towards the synthesis of tyrosol esters with varying chain lengths (C2-C18) within 1 h. Taking the enzymatic transesterification between tyrosol and vinyl acetate as the model reaction, 18 organic solvents and 24 ionic liquids were screened, and their solvent properties (i.e. hydrophobicity, polarity, viscosity, water activity, and partition coefficients of substrate and product) were correlated to the enzyme activity. Upon enzyme screening, four new lipases were found to be highly efficient, relative to the best-performed Novozym 435 and Lipozyme TLIM (Thermomyces lanuginosus lipase (TLL) immobilized on silica gel), in tyrosol ester synthesis. This work provides enzymatic methods of esterifying tyrosol that are much more efficient than those reported in literature, and will shed light on re-consideration of the roles of solvents in nonaqueous enzymology. [ABSTRACT FROM AUTHOR]

A cost-effective, selective, sensitive, and operational TLC-densitometric approach has been adapted for the concurrent assay of Hydroxyzine Hydrochloride (HYX), Ephedrine Hydrochloride (EPH), and Theophylline (THP) in their pure powder and pharmaceutical forms. In the innovative TLC-densitometric approach, HYX, EPH, and THP were efficaciously separated and quantified on a 60F254 silica gel stationary phase with chloroform–ammonium acetate buffer (9.5:0.5, v/v) adjusted to pH 6.5 using ammonia solution as a mobile liquid system and UV detection at 220 nm. The novel TLC method validation has been performed in line with the international conference for harmonization (ICH) standards and has been effectively used for the estimation of the researched medicines in their pharmaceutical formulations without intervention from excipients. Additionally, parameters affecting the chromatographic analysis have been investigated. The new TLC approach's functionality and greenness were appraised using three modern and automated tools, namely the Blue Applicability Grade Index (BAGI), the Analytical Greenness metric (AGREE), and the Green Analytical Procedure Index (GAPI) tools. In short, the greenness characteristics were not achieved as a result of using mandatory, non-ecofriendly solvents such as ammonia and chloroform. On the contrary, the applicability and usefulness of the novel TLC approach were attained via concurrent estimation for the three drugs using simple and straightforward procedures. Moreover, the novel TLC method outperforms previously published HPLC ones in terms of the short run time per sample and moderate pH value for the liquid system. According to the conclusions of comparisons with previously recorded TLC methods, our novel HPTLC method has the highest AGREE score, so it is the greenest HPTLC strategy. Moreover, its functionality and applicability are very appropriate because of the simultaneous assessment of three drugs in one TLC run. Furthermore, no tedious and complicated extraction and evaporation processes are prerequisites. [ABSTRACT FROM AUTHOR]

Geraniol and citronellol are monoterpenoid alcohols with diverse pharmacological activities. This research focuses on synthesized of geranyl laurate and citronellyl laurate using silica gel as an esterification catalyst. The FTIR peak spectra of silica gel showed that Si-OH, Si-O-Si group were observed. XRD showed that the silica gel is an amorphous phase. The reaction was conducted under reflux using a Dean-Stark trap. The reaction was monitored by TLC and then the product was purified using column chromatography. This work reported that silica gel can be utilized as a catalyst for preparing geranyl laurate and citronellyl laurate which proven by the spectra of FTIR, ¹H-NMR, and 13CNMR of the geranyl laurate and citronellyl laurate formed. The IR spectra of geranyl laurate and citronellyl laurate showed the presence of a carbonyl group (C=O) at 1744-1745 cm-1 and C-O from ester at 1170-1176 cm-1. The peak number and its chemical shift on ¹H-NMR and 13C-NMR spectra further verified the structure of geranyl laurate and citronellyl laurate. In conclusion, silica gel can be utilised as a catalyst for preparing geranyl laurat and citronellyl laurate. Therefore, a silica gel-based catalyst is promising to be developed for esterification applications. [ABSTRACT FROM AUTHOR]

Oxidized carbon nanohorn (CNHox) a carbon nanomaterial that has attracted attention due to its unique material properties. It is expected to be applied in various areas like cancer treatment, gene-expression technology, fluids with high thermal conductivity, lubricants, and so on. While the rheological measurements of suspensions provide information on the effective size and interactions of suspended particles, the rheological behaviors of aqueous suspensions of CNHox have never been systematically investigated. To clarify the rheological behaviors of aqueous suspensions of CNHox, their viscosity and dynamic viscoelasticity were measured with changing particle concentration and salt concentration. The viscosity of a CNHox suspension showed yield stress at low shear rates and showed shear-thinning behavior with increasing shear rates. The viscosity of 5 weight % CNHox suspensions was comparable to that of 60 weight % silica suspensions. This high viscosity at a low CNHox concentration is probably due to the porous structure and large effective volume of the CNHox particle. The estimated effective volume of CNHox calculated by the Krieger−Dougherty equation was 18.9 times larger than the actual volume calculated by the mass concentration and density. The dependence of rheological behavior of the CNHox suspension on salt concentration was weak compared to that of the colloidal silica suspension. This weak dependence on salt concentration may be due to the roughness of the particle surface, which would weaken the effect of electric double-layer interactions and/or van der Waals interactions between particles. These rheological behaviors of the aqueous suspension of CNHox shown in this research will be useful in efforts to improve the efficiency of its utilization for the various applications. [ABSTRACT FROM AUTHOR]

Flexible silicone materials have excellent elastic properties and can maintain excellent structural stability under high-intensity repeated deformation. They are ideal materials for preparing piezoresistive flexible sensors. However, traditional silicone materials exhibit strong insulation properties. The solid block structure is also not conducive to improving sensitivity. Inspired by the irregular hole structure of Taihu Lake stone, this paper prepared a porous silica gel skeleton (rGO/CTAB/SG) based on reduced graphene oxide film coating, which was equipped with flexible interdigital electrodes to achieve electrical signal derivation. The "honeycomb" shaped sensing module prepared in this way achieves an extremely wide elastic deformation range (20-200%). In the pressure feedback layer, the rGO film is evenly coated on the SG surface, which greatly improves the device conductivity and sensing performance (high sensitivities of 89.4 kPa− 1 and 25.4 kPa− 1 are achieved within 0-30.2 kPa and 30.2–42 kPa, ultra-high durability under more than 22,000 load-unload cycles.) Numerical simulation analysis results confirmed that the structure of the flexible substrate SG prepared by this method maintained well when extreme deformation occurred, and no fracture or stress concentration occurred. As an elastic sensor, after being integrated with a microprocessor, it can easily monitor and analyze human body movement in real time. It has huge potential in areas such as daily training and health monitoring of athletes. [ABSTRACT FROM AUTHOR]

In this paper, we present a mathematical model and numerical simulation for the evaporation and drying of a liquid droplet containing suspended solids, relevant to processes such as spray drying and spray pyrolysis in the food and pharmaceutical industries. The model comprises three stages: first is the evaporation of the liquid droplet consisting of solid particles, followed by the second stage starting with the formation of a porous crust around a wet-core region and, finally, the third stage with sensible heating of the dry particle. Using a finite difference method with a moving grid, we account for the moving interface between the crust and wet core. Our model incorporates spatial temperature variations and is validated against experimental data on colloidal silica droplet drying, showing good agreement. We examine model assumptions and analyze the impact of drying conditions on drying rate and final particle morphology. Along with the temperature and velocity of the drying gas, we also find that the shape of suspended solid particles inside the droplet and assuming continuum flow of vapor through the crust influence drying quality. Finally, we develop a regime map to predict whether the final particle will be solid or hollow based on operating conditions. [ABSTRACT FROM AUTHOR]

Astaxanthin is a red carotenoid pigment known for its strong antioxidant and immune-supporting properties, which are higher than other carotenoids. The aim of this study was the qualitative and quantitative evaluation of dietary supplements containing astaxanthin. First, optimal conditions for conducting analyses using the TLC technique with densitometric detection were developed. The mobile phase consisting of methanol: ethyl acetate: 1,4-dioxane (1:3:6 v/v/v) was selected, while the stationary phase consisted of Silica gel 60 F254. Densitometric detection was performed at 460 nm. Next, the validation process of the developed method was carried out according to the guidelines of the International Conference on Harmonization (ICH). The range of linearity tested was 0.0026–0.0100 µg/spot, and the determined LOD and LOQ values were 0.85 and 2.57 ng/μL, respectively. The variation coefficient at the level of 4.75% proves good precision. The percentage of recovery was in the range of 95.25–104.94%. The obtained results confirmed the good accuracy of the method. Subsequently, quantitative analyses of the preparations were carried out. Analysis of dietary supplements showed significant deviations from the declared astaxanthin content. Astaxanthin solutions were stable in alkaline environments and when exposed to light and oxidizing substances; however, the substance degraded in acidic environments. The performed antioxidant capacity tests confirmed the high antioxidant activity of astaxanthin. [ABSTRACT FROM AUTHOR]

Although helicenes are promising molecules, the synthetic difficulty and tediousness have often been problems, and only small amounts of optically pure helicenes have been obtained by using chiral HPLC in most cases. Herein, aza[7]helicenes or closed‐aza[7]helicenes with (1R)‐menthyl substituents were selectively synthesized via the intramolecular Scholl reaction, and the diastereomeric pairs were separated by silica gel column chromatography. The optically pure helicenes were further transformed into the corresponding cyclic dimers, and the chiroptical properties were investigated. The rigid π‐frameworks of the dimers led to the high molar extinction coefficients and fluorescence quantum yields, while the twisted helicene moieties induced clear Cotton effects and CPL in the visible region, and the high CPL brightness (BCPL) was achieved. Furthermore, the cyclic dimers were found to have the macrocyclic cavity with the two NH groups suitable for the selective binding of a fluoride anion, which induced significantly redshifted fluorescence and CPL in the red region. [ABSTRACT FROM AUTHOR]

Macrocyclisation of the upper-rim distal disubstituted bromomethylene calix[4]arene derivative proceeds spontaneously on a silica gel due to the spatial proximity of two reaction centers, affording the formation of a bridged calixarene derivative. Due to the short span of the bridge, the product represents an extreme example of calix[4]arenes fixed in the pinched cone conformation with two aromatic rings steeply inclined into the center of the calixarene cavity. Dynamic NMR spectroscopy was used to investigate the temperature-dependent rocking motion of the bridgehead and thermochemical parameters of this motion were determined experimentally, as well as estimated using computational methods. Mass spectrometry was employed to study the upper rim macrocyclization reaction in the gas phase. [ABSTRACT FROM AUTHOR]

Chemodynamic therapy (CDT) alone cannot achieve sufficient therapeutic effects due to the excessive glutathione (GSH) and hypoxia in the tumor microenvironment (TME). Developing a novel strategy to improve efficiency is urgently needed. Herein, we prepared a copper silicate nanoplatform (CSNP) derived from colloidal silica. The Cu(II) in CSNP can be reduced to Cu(I), which cascades to induce a subsequent CDT process. Additionally, benefiting from GSH depletion and oxygen (O2) generation under 660 nm laser irradiation, CSNP exhibits both Fenton-like and hypoxia-alleviating activities, contributing to the effective generation of superoxide anion radical (•O2−) and hydroxyl radical (•OH) in the TME. Furthermore, given the suitable band-gap characteristic and excellent photochemical properties, CSNP can also serve as an efficient type-I photosensitizer for photodynamic therapy (PDT). The synergistic CDT/PDT activity of CSNP presents an efficient antitumor effect and biosecurity in both in vitro and in vivo experiments. The development of an all-in-one nanoplatform that integrates Fenton-like and photosensing properties could improve ROS production within tumors. This study highlights the potential of silicate nanomaterials in cancer treatment. [ABSTRACT FROM AUTHOR]

Camellia fascicularis has important ornamental, medicinal, and food values, which also have tremendous potential for exploiting bioactivities. We performed the bioactivity-guided (antioxidant and antimicrobial) screening of eight fractions obtained from the ethyl acetate phase of C. fascicularis. The antioxidant activity was measured by DPPH, ABTS, and FRAP, and the antibacterial activity was measured by the minimum inhibitory concentration (MIC) of Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus. The results of bioactivity-guided isolation indicated that the major antioxidant compounds in the ethanolic extracts of C. fascicularis may be present in fractions (Fr.) (A–G, obtained after silica gel column chromatography). Fr. (D–I, obtained after silica gel column chromatography) is a fraction of C. fascicularis with antimicrobial activity. The structures of compounds were determined by spectral analysis and nuclear magnetic resonance (NMR) combined with the available literature on secondary metabolites of C. fascicularis leaves. In this study, 17 compounds were identified, including four phenolics (1, 3–4, and 14), a phenylpropane (2), five terpenoids (5–7, 12, and 15), four flavonoids and flavonoid glycosides (8–10 and 16), and two lignins (13 and 17). Compounds 4–7, 13–15, and 17 were isolated from the genus Camellia for first time. The remaining compounds were also isolated from C. fascicularis for first time. The evaluation of antioxidant and antimicrobial activities revealed that compounds 1, 3, 9, 11, and 17 exhibited higher antioxidant activity than the positive control drug (ascorbic acid), and compounds 4, 8, 10, and 13 showed similar activity to ascorbic acid. The other compounds had weaker or no significant antioxidant activities. The MIC of antibacterial activity for compounds 4, 7, and 11–13 against P. aeruginosa was comparable to that of the positive control drug tetracycline at 125 µg/mL, and other secondary metabolites inhibited E. coli and S. aureus at 250–500 µg/mL. This is also the first report of antioxidant and antimicrobial activities of compounds 5–7, 13–15, and 17. The results of the study enriched the variety of secondary metabolites of C. fascicularis and laid the foundation for further research on the pharmacological efficacy and biological activity of this plant. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Resource saving and creation of environmentally safe environment are the guidelines of modern world policy in the field of waste management. This paper considers a possible method of utilization of a by-product of aluminum fluoride production—silica gel—as an alternative high-silica raw material for hydrothermal synthesis of LTA-type zeolites. To obtain synthetic zeolites, industrial silica gel was subjected to sulfuric acid purification and used to obtain one of the hydrogel components—sodium silicate. As a result of investigation of the influence of hydrogel molar composition on the phase composition of the obtained samples, the optimal molar ratios of SiO2:Al2O3, Na2O:Al2O3 and H2O:SiO2 were identified. The phase composition of the obtained samples and morphological pattern were evaluated using X-ray diffraction and scanning electron microscopy techniques. According to the obtained results, the use of hydrogel of composition 1.8SiO2:Al2O3:4Na2O:28H2O allows to obtain a monophase of LTA type zeolite with high ion exchange capacity, the particles of which have a regular cubic shape with the size of the main fraction up to 10 μm. [ABSTRACT FROM AUTHOR]

A combination of fixed dose tablet containing 0.5 mg lobeglitazone sulfate (LBZ) and 1 mg glimepiride (GLM) has demonstrated efficacy in enhancing glycemic control in diabetes. The projected work aimed to develop and validate a high‐performance thin‐layer chromatographic (HPTLC) methodology for the precise quantification of both the drugs in tablet formulations. The HPTLC analysis utilized aluminium plates layered with silica gel 60F254, and the solvent system consisted of ethyl acetate, benzene, and hexane (4:3:1 v/v/v) followed by densitometric scanning at 238 nm. The Rf value was found to be 0.68 ± 0.001 for LBZ and 0.48 ± 0.002 for GLM. The methodology exhibited linearity in the range of 100–2000 ng/band for LBZ and 200–4000 ng/band for GLM, with correlation coefficients of 0.9988 and 0.9981, respectively. Exceptional sensitivity was observed, with detection limits of 23.86 ng/band for LBZ and 58.26 ng/band for GLM, along with quantification limits of 72.32 ng/band for LBZ and 176.55 ng/band for GLM. The method demonstrated precision (% relative standard deviation of peak area < 2) and accuracy (recovery between 97% and 102%). The suggested method is suitable for quantifying both the drugs in tablets, making it useful for routine quality control in laboratories. [ABSTRACT FROM AUTHOR]

Initially, a new organometallic catalyst with nano-silica gel substrate and Ni active center, namely nano-SiO2@nPr@DPyE-Ni was produced, and its properties were thoroughly debated. It was then applied with excellent performance to produce symmetric di-aryl sulfides (14 entries, 78–98%, 20–150 min, EtOH, and 70 °C), and 2-aryl-5-methyl-2,3-dihydro-1H-3-pyrazolones (12 entries, 91–98%, 2–4 min, solvent-free, and r.t). In both production routes, the nanocatalyst was recyclable and reusable for more than seven runs, and its heterogeneous nature was checked and confirmed through the recycling results, hot filtration test, and ICP-OES (coupled plasma optical emission spectroscopy) method. [ABSTRACT FROM AUTHOR]

Silicoaluminophosphate molecular sieves SAPO‑11 were obtained from gels with different silica contents. Silicoaluminophosphates as cubic crystals with 0.5 mm diameter were obtained from gels with SiO2/Al2O3 ratio equal to 0.1, while samples with the ratio SiO2/Al2O3 = 0.5 were obtained as extended prisms with 1‑2 mm diameter. Increasing the SiO2/Al2O3 ratio from 0.1 to 0.4 leads a greater amount of acid sites and a decrease in the specific surface. The conversion of a‑methylstyrene as well as the yield of linear dimers and cyclic trimers both increase with an increasing amount of acid sites and greater external surface. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DES) are a generation of ionic liquids that benefit from low cost, good stability, and environmental-friendly features. In this research, a porous silica gel was impregnated with a eutectic Choline Chloride-Monoethanolamine solvent (ChCl-MEA) to greatly improve its CO2 capture performance. In the impregnation, the weight percentages of ChCl-MEA were used in the range of 10–60 wt% at a temperature of 25 °C. The effect of ChCl-MEA loading on the structural properties of the DES-modified silica samples was studied by BET, FTIR, and TGA analyses. Investigation of the CO2 adsorption performance at different operational conditions showed that the modified silica gel with 50 wt% ChCl-MEA (Silica-CM50) presents the highest CO2 capture capacity of 89.32 mg/g. In the kinetic modeling, the fractional order model with a correlation coefficient of 0.998 resulted in the best fit with the experimental data. In addition, the isotherm data for Silica-CM50 were well-fitted with the Dual site Langmuir isotherm model with a correlation coefficient of 0.999, representing two distinct sites for the adsorption process. Moreover, the thermodynamic parameters including Enthalpy, Entropy, and Gibbs free energy at 25 °C were obtained to be − 2.770, − 0.005 and − 1.162, respectively. The results showed the exothermic, spontaneous and feasibility of the adsorption process. [ABSTRACT FROM AUTHOR]

This article, published in the journal Synlett, discusses a study on the development of a rhodium-catalyzed direct vinylene annulation reaction. The researchers focused on using vinyl selenones as vinylene-transfer reagents and successfully demonstrated a three-component reaction to construct isoquinolone scaffolds. The article includes a table showing the optimization of reaction conditions. The study also explored the scope and limitations of the reaction system, proposing a mechanism for the coupling reaction and concluding that further optimization is needed. [Extracted from the article]

Polysorbate 80 (PS 80) is a nonionic surfactant, used in myriad of pharmaceutical, food and cosmetic formulations. PS 80 components have strong UV absorbance and retain under reversed-phase chromatographic conditions, significantly masking sections of the chromatogram. PS 80-related peaks interferences in a sample are common and can be difficult to separate from the analyte peaks. A liquid oral finished product (LOFP) containing PS 80 and Ivermectin as the active pharmaceutical ingredient (API) was selected for this study. Herein, we report two sample pretreatment strategies focusing on the selective removal of PS 80 from the LOFP. Both methods significantly reduce and/or practically eliminate excipients and PS 80-related peaks interferences from the LOFP without a negative impact on the API and its key-related substances recovery. The solid-phase extraction (SPE) strategy uses a C18 SPE followed by a silica gel SPE, whereas the liquid–liquid extraction strategy uses in situ -generated sodium caprylate for the removal of formulation excipients and PS 80. These methods can significantly increase the reliability of high-performance liquid chromatography methods and decrease false positive out-of-specifications events because of coelution of PS 80-related peaks with peaks of interest. [ABSTRACT FROM AUTHOR]

Accurate, sensitive and green HPTLC chromatographic method was proposed for simultaneous determination of metformin, glipizide and sitagliptin in the presence of metformin potential toxic impurities melamine and cyanoguanidine. The separation was completed on silica gel HPTLC F254 plates using a mixture of ethyl acetate: methanol: ammonia: formic acid (7: 2: 0.2: 0.2, by volume) as a developing system with UV scanning for the developed bands at 235 nm. The R f values for metformin, glipizide, sitagliptin, melamine and cyanoguanidine were 0.17, 0.84, 0.67, 0.47 and 0.75, respectively. Linear responses were observed in the ranges of 0.2–3, 0.07–1.5, 1.5–5, 0.8–4 and 0.4–2 μg/band with correlation coefficients of 0.9999, 0.9998, 0.9997, 0.9996 and 0.9998 for metformin, glipizide, sitagliptin, melamine and cyanoguanidine, respectively. The proposed method was validated as per ICH criteria with respect to linearity, accuracy, precision, specificity and robustness. The validated method was successfully applied for determination of the studied drugs in Janumet® and Engilor® tablets; also, the results were statistically compared to those obtained by the reported spectrophotometric method and no significant difference was found between them. This method permitted the accurate simultaneous determination of the studied drugs, indicating its ability to be used for routine quality control assays of these drugs. [ABSTRACT FROM AUTHOR]

This article discusses the importance of protecting amines in organic synthesis to prevent unwanted side reactions, particularly in the synthesis of complex peptides, amino acids, and natural products. Various methods for amine protection are explored, including formylation, acetylation, alkylation, and the use of specific groups like Boc, Cbz, and Fmoc. The article introduces a new dicationic catalyst, [C4(Tr)2]·2Cl, for the N-Boc protection and acetylation of amines under solvent-free conditions. The catalyst is shown to be effective in producing N-tert-butylcarbamates and N-acetamides with high yields and minimal variation based on substituents. The method is selective and does not damage structural units like the methoxy group. The efficiency of this method is compared to other reported methods and is shown to have favorable reaction times, yields, and mild conditions. The catalyst is easily prepared, reusable, and environmentally friendly. The article provides detailed experimental procedures and characterization data for the catalyst and the synthesized compounds. The authors hope that this new catalyst will find further applications in synthesis. [Extracted from the article]

Purpose: This study aims to perform the surface treatment of synthetic α-Fe2O3 red iron oxide pigment with hydrolysate 3-aminopropyl silane (A) and colloidal silica (CS) and investigate the effects of surface-treated pigment on the styrene acrylic (SA) emulsion and polyurethane (PU) dispersion. Design/methodology/approach: For this purpose, firstly red iron oxide particles were modified with A and CS separately in an aqueous medium. After isolation of the modified iron oxide were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Moreover, the degree of the dispersion stability of the modified pigment in coatings with SA emulsion and PU dispersion was investigated by using an oscillation rheometer. Loss (G''), storage (G') modulus, loss factor [tan(δ)] and yield stress (τ0) values were determined by performing amplitude and frequency sweep tests. Findings: The τ0 in SA coatings decreases with the amount of used A and increases with the amount of used CS. The τ0 decreases as the amount of used A and CS in PU coatings increases. The use of CS on red iron oxide pigments causes storage modulus to increase in SA coatings at low angular frequencies, while it causes a decrease in PU coatings. Originality/value: To the best of the authors' knowledge, for the first time, the suspended state of the iron oxide hybrid pigment formed with CS in the coating was investigated rheologically in this study. [ABSTRACT FROM AUTHOR]

This article, published in the Chemistry of Natural Compounds journal, discusses the chemical constituents found in the leaves of Camellia ptilosperma, a yellow camellia species. The study reveals the presence of twenty compounds, including alcohols, sesquiterpenes, monoterpenes, triterpenes, pheophorbides, and ginsenosides. The structure of these compounds was determined using spectroscopic data. The cytotoxicity of these compounds against six cancer cell lines was also evaluated, with some compounds showing weak to moderate cytotoxicity. This research provides valuable insights into the chemical composition and potential medicinal properties of Camellia ptilosperma. [Extracted from the article]

This article, published in Chemistry of Natural Compounds, explores the chemical composition of compounds found in the rhizomes of Hedychium coronarium, a plant traditionally used for medicinal purposes. The study reveals that the plant contains bioactive compounds such as terpenoids, flavonoids, steroids, and simple aromatics. The researchers used extraction and purification techniques to isolate and characterize these compounds, providing detailed information about their chemical structures. Some of the identified compounds, including Kaempferol-3,7,4'-O-trimethylether and Pinocembrin, were discovered in H. coronarium for the first time. The research was conducted in Yunnan, China, with support from the Key Laboratory and Science and Technology Innovation Team of Higher Education. [Extracted from the article]

A study published in the Chemistry of Natural Compounds journal explored the potential anti-liver and colorectal cancer properties of compounds found in the leaves of Michelia crassipes. The study identified various chemical constituents in the plant and tested their ability to inhibit the growth of cancer cells. The results showed that these compounds were effective in suppressing the proliferation of liver and colorectal cancer cells, with lower toxicity to normal cells compared to the current chemotherapy drug. The document provides information on the extraction and isolation process of these compounds, as well as the support received from Yuan's General Hospital. [Extracted from the article]

This article, published in the Chemistry of Natural Compounds journal, discusses the discovery of a new species of Michelia plant, M. compressa var. lanyuensis, found only in Lanyu, Taiwan. The focus of the article is on the chemical analysis of the plant and the isolation of sixteen compounds from its flowers. The antioxidative activity of these compounds was tested, and three of them, o-hydroxybenzoic acid, N-trans-caffeoyltyramine, and N-cis-caffeoyltyramine, showed strong antioxidative properties. The article provides detailed information on the collection, identification, extraction, and isolation processes used, as well as the chemical and physical properties of the compounds. The experiments conducted to evaluate the antioxidant abilities of the compounds included testing their ability to scavenge free radicals, chelate metal ions, and exhibit reducing power. The results indicated that the three mentioned compounds exhibited significant antioxidative activity. The investigation was supported by a grant from Yuan's General Hospital. [Extracted from the article]

Employing the Molecular Electron Density Theory, [3 + 2] cycloaddition processes between 4-chlorobenzenenitrileoxide and linalool, have been applied using the DFT/B3LYP/6–311(d,p) method, activation, reaction energies and the reactivity indices are calculated. In an investigation of conceptual DFT indices, LIL-1 will contribute to this reaction as a nucleophile, whilst NOX-2 will participate as an electrophile. This cyclization is regio, chemo and stereospecific, as demonstrated by the reaction and activation energies, in clear agreement with the experiment's results, in addition, ELF analysis revealed that the mechanism for this cycloaddition occurs in two steps. Furthermore, a docking study was conducted on the products studied, and the interaction with the protein protease COVID-19 (PDB ID: 6LU7), our results indicate that the presence of the –OH group increases the affinity of these products, moreover, adsorption study by chromatography was made on silica gel as support; our outcome reveals that the –OH group creates an intramolecular hydrogen bond in the product P2, while in the product P3 will create a hydrogen bond with the silica gel which makes the two products P2 and P3 are very easy to separate by chromatography, this result is in excellent agreement with the Rf retention value. The study might provide a fundamental for developing natural anti-viral compound in promoting human health. [ABSTRACT FROM AUTHOR]

MIL-101 (Cr) Was synthesized by hydrothermal method, and its phase structure and micro- structure were characterized by PXRD and SEM, resulting in a BET of 2 800 m²/g of MIL-101 adsorbent. The static adsorption experiment showed that MIL-101 had saturated mass adsorption rate of 8.36% and 7.05% for Andrographolide and dehydrated Andrographolide in a 60% methanol aqueous solution, respectively; MIL-101 was loaded onto chromatographic silica gel to prepare a chromatographic column (4.6 mm x 250 mm), and its penetration curves for two types of lactones and online separation performance for lactone mixtures were measured. The results showed that the experimental prepared chromatographic column had a separation degree of 1.9 for Andrographolide and dehydrated Andrographolide, with a separation efficiency of >99%, achieving online efficient separation. [ABSTRACT FROM AUTHOR]

In order to understand the distribution characteristics of water content in the process of silica gel adsorption and dehydration, the influence of desorption temperature on the adsorption capacity and phase structure of silica gel was studied. The effects of desorption atmosphere, desorption temperature, desorption time, water content, and desorption times on the effective residual water of silica gel were studied. The effective adsorption water of silica gel under different desorption conditions was calculated. The results showed that when the desorption temperature was not greater than 130 °C, the adsorption capacity did not decay and the structure remained stable. The effective residual water of silica gel is related to the desorption temperature and atmosphere, but not to the pre desorption water content and desorption times. When desorbing in an air atmosphere, the optimal desorption condition is 130 °C, 1 h, and the effective residual water is 8. 5% ~9. 1%. When adsorbed for 20 ~ 150 min, the effective adsorbed water increases linearly with adsorption time, especially when adsorbed for 120 ~ 150 min, the effective adsorbed water reaches 12% ~ 14%. [ABSTRACT FROM AUTHOR]

This title compound, C20H26O2, was isolated from the benzene fraction of the stem bark of Staudtia kamerunensis Warb. (Myristicaceae) using column chromatography techniques over silica gel. The compound was fully characterized by single-crystal X-ray diffraction, one and two-dimensional NMR spectroscopy, IR and MS spectrometry. The compound has two fused cyclo­hexane rings attached to a benzene ring, with a carb­oxy­lic acid on C-4. This cyclo­hexene ring has a chair conformation while the other adopts a half-chair conformation. The benzene ring is substituted with a propenyl moiety. The structure is characterized by inter­molecular O--H...O hydrogen bonds, two C--H...O intra­molecular hydrogen bonds and two C--H...π inter­actions. The mol­ecular structure confirms previous studies carried out by spectroscopic techniques. [ABSTRACT FROM AUTHOR]

This article discusses the optimization of the synthesis of pyridin-2(1 H)-ones, which have potential as pain-relieving compounds. The researchers aimed to discover novel analgesic compounds that are more effective and safe for managing chronic pain. They conducted a study to improve the synthesis of a specific compound and prepared analogues to evaluate their efficacy in preventing mechanical allodynia in a rat model. The text provides a series of procedures for the synthesis and purification of various compounds, along with characterization data such as melting point and spectroscopic data. The document also briefly mentions a behavioral study conducted on rats to assess the effects of the synthesized compounds on mechanical hypersensitivity. [Extracted from the article]

This article discusses a new method for synthesizing halogenated heterocycles, which are important in medicinal, materials, and agricultural chemistry. The authors propose a base-mediated cyclization method that is simple, robust, and scalable, providing good to excellent yields of indoles, benzofurans, and benzothiophenes. The text provides a detailed description of the experimental procedures and characterization data for the synthesis of various compounds, including IR spectra, NMR spectra, and high-resolution mass spectra. This information can be useful for researchers studying organic synthesis and chemical characterization. [Extracted from the article]