Investigation of mechanical and thermal behavior of fiber-reinforced silica xerogel composites.

Silica aerogels or xerogels are renowned dried gels with low density, high surface area, higher porosity, and better thermal stability which makes it suitable for aerospace, light weight structures, thermal insulation, and hydrophobic coatings. But brittle behaviour, low mechanical strength, and high manufacturing cost restrict its usage. Recently, the addition of various fibres like glass or carbon fiber is one of the best reinforcement methods to minimize the brittle behaviour. Supercritical drying technique usually used to develop aerogel that is expensive and difficult to produce in bulk quantities. Higher cost obstacle can be tackled by applying ambient pressure drying technique to develop xerogel. But researcher observed cracks in samples prepared through the ambient pressure drying technique is still a major shortcoming. The aim of this study is to systematically analyze the influence of silica gel fiber reinforcement on silica xerogels, encompassing morphology, mechanics, thermal behaviour, compression test, and thermogravimetric characteristics. The research used a low-cost precursor named Tetraethyl orthosilicate to synthesize low-cost composite Silica xerogel and glass and carbon fiber added to provide strength and flexibility to the overall composite. Silica gel works as binder in strengthening the xerogel network. The investigation employs scanning electron microscopy (SEM) to examine the morphology of the composites, Fourier Transform Infrared (FTIR) analysis to affirm hydrophobic characteristics, compression tests to assess mechanical strength, and thermogravimetric tests to study weight loss under different conditions. SEM results reveals that glass fibers exhibit lower adhesion to the xerogel network compared to carbon fibers. FTIR analysis confirms the hydrophobicity of the composite silica xerogel. Compression tests showed that, under a 48% strain rate, the carbon fiber composite demonstrates superior compressive stress endurance. Thermogravimetric tests revealed a 1% lower weight loss for the carbon fiber composite compared to the glass fiber composite. This work concludes that glass and carbon fiber together with silica gel particles successfully facilitated in developing flexible, less costly, hydrophobic, and crack-free silica xerogel composites by APD. These advancements have the potential to drive innovations in material science and technology across diverse industries.

A novel and recyclable silica gel-modified biochar to remove cadmium from wastewater: Model application and mechanism exploration.

Water pollution caused by heavy metals is a major environmental problem, threatening water production, food safety, and human health. Cadmium (Cd) pollution is particularly serious because of food-chain biomagnification at toxic concentrations. Modified biochar is promising for heavy metal removal; however, efficient adsorbents for Cd removal are lacking. In the present study, a novel adsorbent, silica gel-modified biochar (SGB), was prepared and applied to treat sewage polluted by Cd. Through the batch adsorption experiments, it is known that SGB possessed outstanding Cd removal ability and recycleability. Furthermore, the adsorption behavior and mechanisms were analyzed by the application of kinetic and isotherm models. The maximum Cd2+ adsorption capacity of SGB was 38.08 mg g-1, and after five recycling processes, the Cd2+ removal rate was still 86.89 %. When the pH of the solution was 7.0, SGB showed the strongest Cd2+ adsorption capacity (29.06 mg g-1). When competitive ions existed, biochar also had high Cd removal efficiency, although the effect of Pb2+ was greater than those of Cu2+ and Zn2+, indicating that SGB was applicable to complex polluted water. Additionally, the main Cd2+ adsorption mechanisms by SGB were electrostatic interactions, π-π interactions, complexation, and co-precipitation. These results showed that SGB can effectively treat Cd-contaminated wastewater as a new adsorbent.

Anti-Trichomonas vaginalis Activity of Marine Ascidians (Tunicates; Ascidiacea) from the Bushehr Province, Iran

Objective: The aim of the current research is to evaluate the antiparasite effects of compounds isolated from marine ascidian tunicates on Trichomonas vaginalis. Methods: Ascidian tunicates after collection were cut into small pieces, freeze-dried, and powdered. The resulting material was subjected to extraction in double-distilled water, ethanol, n-hexane, and dichloromethane. To fractionate the extracts and identify the most bioactive compound, silica gel column chromatography and GC-M/S analysis were used. Results: Fraction 18 of silica gel column chromatography of ethanol extract was the most effective against T. vaginalis. The respective IC50, CC50, and SI values for fraction 18 were 28.62 µg/mL, ˃800 µg/mL, and ˃27.95. GC-M/S analysis of this fraction identified a major phenolic compound (2, 4-bis (1, 1-dimethyl ethyl), whose toxicity against vero cells was only 10.15%. Conclusion: The ethanolic fraction containing phenol-2,4-bis (1,1-dimethylethyl), which has a potent lethality effect on T. vaginalis, may be considered as an antiparasite drug candidate.

Biomimetic tri-layered artificial skin comprising silica gel-collagen membrane-collagen porous scaffold for enhanced full-thickness wound healing.

Full-thickness wounds are severe cutaneous damages with destroyed self-healing function, which need efficient clinical interventions. Inspired by the hierarchical structure of natural skin, we have for the first time developed a biomimetic tri-layered artificial skin (TLAS) comprising silica gel-collagen membrane-collagen porous scaffold for enhanced full-thickness wound healing. The TLAS with the thickness of 3-7 mm displays a hierarchical nanostructure consisting of the top homogeneous silica gel film, the middle compact collagen membrane, and the bottom porous collagen scaffold, exquisitely mimicking the epidermis, basement membrane and dermis of natural skin, respectively. The 1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide/N-Hydroxysuccinimide-dehydrothermal (EDC/NHS-DHT) dual-crosslinked collagen composite bilayer, with a crosslinking degree of 79.5 %, displays remarkable biocompatibility, bioactivity, and biosafety with no risk of hemolysis and pyrogen reactions. Notably, the extra collagen membrane layer provides a robust barrier to block the penetration of silica gel into the collagen porous scaffold, leading to the TLAS with enhanced biocompatibility and bioactivity. The full-thickness wound rat model studies have indicated the TLAS significantly facilitates the regeneration of full-thickness defects by accelerating re-epithelization, collagen deposition and migration of skin appendages. The highly biocompatible and bioactive tri-layered artificial skin provides an improved treatment for full-thickness wounds, which has great potential in tissue engineering.

[Analytical Method for Melengestrol Acetate in Livestock Products Using LC-MS/MS].

The present study verified that it is possible to analyze melengesterol acetate using the existing multi-residue method. Melengestrol acetate was extracted from livestock products using acidic acetonitrile acidified with acetic acid in the presence of n-hexane and anhydrous sodium sulfate. The crude extracts were cleaned up using an octadecylsilanized silica gel cartridge column. Separation by HPLC was performed using an octadecylsilanized silica gel column with linear gradient elution of 0.1 vol% formic acid and acetonitrile containing 0.1 vol% formic acid. For the determination of the analyte, tandem mass spectrometry with positive ion electrospray ionization was used. In recovery tests using four livestock products fortified with maximum residue limits levels of melengestrol acetate (0.001-0.02 mg/kg), the truenesses ranged from 82% to 100%, and the repeatabilities for the entire procedure ranged from 0.5 RSD% to 5.6 RSD%. In recovery tests using 11 livestock products fortified with 0.0005 mg/kg of melengestrol acetate, the truenesses ranged from 88% to 99%, and the repeatabilities ranged from 1.3 RSD% to 5.4 RSD%. The limit of quantification for melengestrol acetate in livestock products was 0.0005 mg/kg.

Drying as an effective method to store soil samples for DNA-based microbial community analyses: a comparative study.

Soil sampling for environmental DNA in remote and semi-remote locations is often limited due to logistical constraints surrounding sample preservation, including no or limited access to a freezer. Freezing at - 20 °C is a common DNA preservation strategy, however, other methods such as desiccation, ethanol or commercial preservatives are available as potential alternative DNA preservation methods for room temperature storage. In this study, we assessed five preservation methods (CD1 solution, 95% Ethanol, Dry & Dry silica gel packs, RNAlater, LifeGuard) along with freezing at - 20 °C, against immediate extraction on organic and mineral soils for up to three weeks of preservation. We assessed direct effects on DNA concentration and quality, and used DNA metabarcoding to assess effects on bacterial and fungal communities. Drying with Dry & Dry led to no significant differences from immediate extraction. RNAlater led to lower DNA concentrations, but effects on community structures were comparable to freezing. CD1, LifeGuard and Ethanol either caused immediate significant shifts in community structure, degradation of DNA quality or changes in diversity metrics. Overall, our study supports the use of drying with silica gel packs as a cost-effective, and easily applied method for the short-term storage at room temperature for DNA-based microbial community analyses.

A high-performance polymer composite column for coronavirus nucleic acid purification.

Here, we report the development of a novel polymer composite (PC) purification column and kit. The performance of the PC columns was compared to conventional silica gel (SG) columns for the purification of nucleic acids from coronaviruses, including SARS-CoV-2, in 82 clinical samples. The results shows that PC-based purification outperforms silica gel (SG)-based purification by enabling a higher sensitivity (94%), accuracy (97%), and by eliminating false positives (100% specificity). The high specificity is critical for efficient patient triage and resource management during pandemics. Furthermore, PC-based purification exhibits three times higher analytical precision than a commonly used SG-based nucleic acid purification thereby enabling a more accurate quantification of viral loads and higher reproducibility.

Chemically Bonded Pepsin via Its Inert Center to Diazo Functionalized Silica Gel through Multipoint Attachment Mode: A Way of Restoring Biocatalytic Sustainability over "Wider pH" Range.

Proteolytic enzymes play a pivotal role in the industry. Still, because of denaturation, the extensive applicability at their level of best catalytic efficiency over a more comprehensive pH range, particularly in alkaline conditions over pH 8, has not been fully developed. On the other hand, enzyme immobilization following a suitable protocol is a long pending issue that determines the conformational stability, specificity, selectivity, enantioselectivity, and activity of the native enzymes at long-range pH. As a bridge between these two findings, in an attempt at a freezing temperature 273-278 K at an alkaline pH, the diazo-functionalized silica gel (SG) surface has been used to rapidly diazo couple pepsin through its inert center, the O-carbon of the phenolic -OH of surface-occupied Tyr residues in a multipoint mode: when all the various protein groups, viz., amino, thiol, phenol, imidazole, carboxy, etc., in the molecular sequence including those belonging to the active sites, remain intact, the inherent inbuilt interactions among themselves remain. Thereby, the macromolecule's global conformation and helicity preserve the status quo. The dimension of the SG-enzyme conjugate confirms as {Si(OSi)4 (H2O)1.03}n {-O-Si(CH3)2-O-C6H4-N═N+}4·{pepsin}·yH2O; where the values of n and y have been determined respectively as 347 and 188. The material performs the catalytic activity much better at 7-8.5 than at pH 2-3.5 and continues for up to six months without any appreciable change.

Establishment of Polydopamine-Modified HK-2 Cell Membrane Chromatography and Screening of Active Components from Plantago asiatica L.

Cell membrane chromatography (CMC) has been widely recognized as a highly efficient technique for in vitro screening of active compounds. Nevertheless, conventional CMC approaches suffer from a restricted repertoire of cell membrane proteins, making them susceptible to oversaturation. Moreover, the binding mechanism between silica gel and proteins primarily relies on intermolecular hydrogen bonding, which is inherently unstable and somewhat hampers the advancement of CMC. Consequently, this investigation aimed to establish a novel CMC column that could augment protein loading, enhance detection throughput, and bolster binding affinity through the introduction of covalent bonding with proteins. This study utilizes polydopamine (PDA)-coated silica gel, which is formed through the self-polymerization of dopamine (DA), as the carrier for the CMC column filler. The objective is to construct the HK-2/SiO2-PDA/CMC model to screen potential therapeutic drugs for gout. To compare the quantity and characteristics of Human Kidney-2 (HK-2) cell membrane proteins immobilized on SiO2-PDA and silica gel, the proteins were immobilized on both surfaces. The results indicate that SiO2-PDA has a notably greater affinity for membrane proteins compared to silica gel, resulting in a significant improvement in detection efficiency. Furthermore, a screening method utilizing HK-2/SiO2-PDA/CMC was utilized to identify seven potential anti-gout compounds derived from Plantago asiatica L. (PAL). The effectiveness of these compounds was further validated using an in vitro cell model of uric acid (UA) reabsorption. In conclusion, this study successfully developed and implemented a novel CMC filler, which has practical implications in the field.

High-Density Immobilization of TCEP on Silica Beads for Efficient Disulfide Reduction and Thiol Alkylation in Peptides.

Tris-(2-carboxyethyl)phosphine (TCEP) linked to agarose beads is widely used for reducing disulfide bridges in proteins and peptides. The immobilization of TCEP on beads allows efficient removal after reduction to prevent its reaction with alkylating reagents and thus interference with conjugation reactions. However, a limitation of agarose TCEP is its relatively low reduction capacity per milliliter of wet beads (about 15 µmol/ml), making it unsuitable for the reduction of disulfides from molecules at millimolar concentrations. In this work, we tested the immobilization of TCEP to a range of different solid supports and found that conjugation to silica gel offers TCEP beads with about 8-fold higher reduction capacity (129±16 µmol/ml wet beads). We show that it allows reducing disulfide-cyclized peptides at millimolar concentrations for subsequent cyclization by bis-electrophile linker reagents. Given the substantially higher reduction capacity, the robust performance in different solvents, the low cost of the silica gel, and the ease of functionalization with TCEP, the silica gel-TCEP is suited for reducing disulfide bridges in essentially any peptide and is particularly useful for reducing peptides at higher concentrations.

A small-scale silica gel column chromatography method for separating carbazole compounds from highly mature crude oil.

The concentration of carbazoles in highly mature crude oil is quite low, making it challenging to separate carbazole compounds for the gas chromatography-mass spectrometry (GC-MS) detection. This study presents a small-scale column chromatography method for separating carbazoles from highly mature crude oil using silica gel as a solid phase adsorbent and a Pasteur pipette as a separation device. The carbazole-rich crude oil from the Pearl River Mouth Basin was selected to explore the impact of reagent polarity and injection mode on the separation of carbazoles. The oil sample was eluted with solvents mixed with different volume proportions of n-hexane and dichloromethane and each eluted fraction was collected for GC-MS testing. The results indicated that increasing the reagent polarity caused the aromatic hydrocarbons and carbazole compounds in crude oil to be eluted sequentially. Most aromatic compounds in the crude oil could be selectively eluted using a reagent polarity ratio of 9:1 (Vn-hexane: Vdichloromethane), with no carbazole compounds. A significant amount of carbazole compounds were eluted in the polar segments of 8:2-6:4, with the eluted carbazoles concentration accounting for more than 98 % of the total concentration. Moreover, the concentration and recovery of carbazoles eluted by direct injection mode were about 10 % higher than those after adsorption by silica gel. The standard deviation of the parameter ratio for the separated carbazole compounds in the three groups of repeatable parallel experiments was less than 0.2 %. Our method is superior to traditional two-step method and C18 column method in separation efficiency and damage to human body. This method can be applied to both highly mature crude oil and other kinds of oils including biodegradable oil. It could be a versatile method for the carbazoles separation and provide technical support in unveiling the geochemical implications of these compounds in complex areas.

A non-inferiority study to compare the effect of silica gel fiber dressing with alginate dressing on healing of venous leg ulcers.

BACKGROUND: Silica gel fiber (SGF) dressing is a novel patch for wound healing. OBJECTIVE: To compare the efficacy and safety of SGF dressing with alginate dressing in local treatment of venous leg ulcers. METHODS: Patients with venous leg ulcers who had undergone effective treatment of venous hypertension and debridement were randomized to receive wound care with either SGF dressing or alginate dressing for 4 weeks. Wounds were assessed weekly during the first 4 weeks and then every 2 weeks until the 8th week. The primary endpoint was the efficacy rate. Secondary endpoints included ulcer area reduction rate, healing rate, frequency of dressing changes, pain score, patient satisfaction, and treatment-related adverse events. RESULTS: A total of 130 patients were enrolled, 67 treated with SGF and 63 with alginate dressing, and the efficacy rates were 89.6% (SGF group) and 84.1% (alginate group). SGF induced a higher "no pain" rate than alginate at week 2 (61.4% vs 43.5%) and week 3 (67.6% vs 53.1%), and a higher "highly satisfied" rate at week 4 (83.3% vs 78.8%) and week 8 (75% vs 59.1%). Markedly fewer dressing changes were required in the SGF group. CONCLUSIONS: SGF dressing is non-inferior to alginate dressing in treating venous leg ulcers. It even substantially decreased the frequency of dressing changes when compared with alginate dressing.

High-throughput microfluidic chip with silica gel-C18 channels for cyclotide separation.

Over the past two decades, microfluidic-based separations have been used for the purification, isolation, and separation of biomolecules to overcome difficulties encountered by conventional chromatography-based methods including high cost, long processing times, sample volumes, and low separation efficiency. Cyclotides, or cyclic peptides used by some plant families as defense agents, have attracted the interest of scientists because of their biological activities varying from antimicrobial to anticancer properties. The separation process has a critical impact in terms of obtaining pure cyclotides for drug development strategies. Here, for the first time, a mimic of the high-performance liquid chromatography (HPLC) on microfluidic chip strategy was used to separate the cyclotides. In this regard, silica gel-C18 was synthesized and characterized by Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR) and then filled inside the microchannel to prepare an HPLC C18 column-like structure inside the microchannel. Cyclotide extract was obtained from Viola ignobilis by a low voltage electric field extraction method and characterized by HPLC and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF). The extract that contained vigno 1, 2, 3, 4, 5, and varv A cyclotides was added to the microchannel where distilled water was used as a mobile phase with 1 µL/min flow rate and then samples were collected in 2-min intervals until 10 min. Results show that cyclotides can be successfully separated from each other and collected from the microchannel at different periods of time. These findings demonstrate that the use of microfluidic channels has a high impact on the separation of cyclotides as a rapid, cost-effective, and simple method and the device can find widespread applications in drug discovery research.

Biomediated control of colloidal silica grouting using microbial fermentation.

Colloidal silica grouting is a ground improvement technique capable of stabilizing weak problematic soils and achieving large reductions in soil hydraulic conductivities for applications including earthquake-induced liquefaction mitigation and groundwater flow control. In the conventional approach, chemical accelerants are added to colloidal silica suspensions that are introduced into soils targeted for improvement and the formation of a semi-solid silica gel occurs over time at a rate controlled by suspension chemistry and in situ geochemical conditions. Although the process has been extensively investigated, controlling the rate of gel formation in the presence of varying subsurface conditions and the limited ability of conventional methods to effectively monitor the gel formation process has posed practical challenges. In this study, a biomediated soil improvement process is proposed which utilizes enriched fermentative microorganisms to control the gelation of colloidal silica grouts through solution pH reductions and ionic strength increases. Four series of batch experiments were performed to investigate the ability of glucose fermenting microorganisms to be enriched in natural sands to induce geochemical changes capable of mediating silica gel formation and assess the effect of treatment solution composition on pH reduction behaviors. Complementary batch and soil column experiments were subsequently performed to upscale the process and explore the effectiveness of chemical, hydraulic, and geophysical methods to monitor microbial activity, gel formation, and engineering improvements. Results demonstrate that fermentative microorganisms can be successfully enriched and mediate gel formation in suspensions that would otherwise remain highly stable, thereby forgoing the need for chemical accelerants, increasing the reliability and control of colloidal silica grouting, enabling new monitoring approaches, and affording engineering enhancements comparable to conventional colloidal silica grouts.

Liquid chromatography on a centrifugal platform for separation and collection of water-soluble dyes.

A reversed-phase chromatographic process is developed on a centrifugal platform to separate and collect water-soluble dyes from a mixture. A separation column filled with C18-reversed phase silica gel was used to separate the components from a mixture and the eluate was collected by a series of collecting chambers. The purified components can then be identified and extracted from the collecting chambers. The effects of the silica gel's particle size (7-10, 20-45, and 46-63 µm) and the platform's rotational speed (1000, 1500, 2000 RPM) on the separation and collection efficiency were investigated. Experimental results showed that dye separation could be well performed in the column with smaller-sized silica gels (7-10 µm) under a low rotational speed (1000 RPM). However, for the eluate collection, the high eluent flowrate and long processing time resulted in a convective band-broadening problem in the collecting chambers, which affected the recovery ratio of the dyes. Experimental results showed that the convective band broadening effect can be reduced by reducing the flowrate, shortening the collecting time, and switching the eluent to a different composition. The best recovery ratio of the dyes in the current design can be achieved by using the column with a powder size distribution of 46-63 µm and operating at the rotational speed of 1500 RPM. This platform can process a sample volume of 1 µL and the processing time is about 30 min. Since the only instrument used is a motor, the complete chromatographic process, from separation to fraction collection, can be carried out on a centrifugal platform at a low cost.

Chitosan-Silica Composites for Adsorption Application in the Treatment of Water and Wastewater from Anionic Dyes.

A series of new types of composites (biopolymer-silica materials) are proposed as selective and effective adsorbents. A new procedure for the synthesis of chitosan-nanosilica composites (ChNS) and chitosan-silica gel composites (ChSG) using geometrical modification of silica and mechanosorption of chitosan is applied. The highest adsorption efficiency was achieved at pH = 2, hence the desirability of modifications aimed at stabilizing chitosan in such conditions. The amount of chitosan in the synthesis grew to 1.8 times the adsorption capacity for the nanosilica-supported materials and 1.6 times for the silica gel-based composites. The adsorption kinetics of anionic dyes (acid red AR88) was faster for ChNS than for ChSG, which results from a silica-type effect. The various structural, textural, and physicochemical aspects of the chitosan-silica adsorbents were analyzed via small-angle X-ray scattering, scanning electron microscopy, low-temperature gas (nitrogen) adsorption, and potentiometric titration, as well as their adsorption effectiveness towards selected dyes. This indicates the synergistic effect of the presence of dye-binding groups of the chitosan component, and the developed interfacial surface of the silica component in composites.

A home-based approach to demonstrate column and thin layer chromatography during the COVID-19 pandemic.

The COVID-19 pandemic caused several educational challenges. Conducting laboratory experiments was an uphill task during the pandemic. Here, we developed a low-cost and reliable home-based experimental setup to teach column and thin layer chromatography (TLC) using silica gel granules available at home. Powdered silica gel, prepared by grinding silica gel granules, was used as the stationary phase. Iso-propyl alcohol, purchased from a pharmacy, was diluted with water and used as the mobile phase. A food coloring was chromatographically separated using the designed column. Moreover, TLC plates were prepared using powdered silica gel and a drop of food coloring was separated on TLC plates using the same mobile phase. In the article, we show our experiences by providing methods used to implement this experimental setup. We assume that this experimental setup will be helpful for other universities, research institutes and schools to develop online laboratory curricula to demonstrate basic chromatography techniques required for subjects such as chemistry, biochemistry and biology.

[Chemical constituents of roots of Rodgersia aesculifolia].

The chemical compositions of Rodgersia aesculifolia were isolated and purified using a combination of silica gel, reverse phase silica gel, Sephadex LH-20 column chromatography, and semi-preparative HPLC. The structures were determined according to the physicochemical properties and spectroscopic data. The MTT method and the ABTS kit were used to measure the cytotoxicity and antioxidant capacity of all isolates, respectively. Thirty-four compounds were isolated from R. aesculifolia and elucidated as stigmastane-6ß-methoxy-3ß,5α-diol(1), stigmastane-3ß,5α,6ß triol(2), ß-sitosterol(3), ß-daucosterol(4), stigmast-4-en-3-one(5), bergenin(6), 11-ß-D-glucopyranosyl-bergenin(7), 11-O-galloybergenin(8), 1,4,6-tri-O-galloyl-ß-D-glucose(9), gallic acid(10), 3,4-dihydroxybenzoic acid methyl ester(11), ethyl gallate(12), ethyl 3,4-dihydroxybenzoate(13), caffeic acid ethyl ester(14), p-hydroxybenzeneacetic acid(15), 4-hydroxybenzoic acid(16), 2,3-dihydroxy-1-(4-hydroxy-3-methoxyphenyl)-propan-1-one(17), 3,7-dimethyl-2-octene-1,7-diol(18), crocusatin-B(19), neroplomacrol(20), geniposide(21), 3-hydroxyurs-12-en-27-oic acid(22), 3ß-trans-p-coumaroyloxy-olean-12-en-27-oic acid(23), aceriphyllic acid G(24), isolariciresinol(25), trans-rodgersinine B(26), cis-rodgersinine A(27), neo-olivil(28),(7S,8R)-dihydro-3'-hydroxy-8-hydroxy-methyl-7-(4-hydroxy-3-methoxy phenyl)-1'-benzofuranpropanol(29), 5,3',4'-trihydroxy-7-methoxyflavanone(30), quercetin 3-rutinoside(31), catechin-[8,7-e]-4ß-(3,4-dihydroxy-phenyl)-dihydro-2(3H)-pyranone(32), ethyl α-L-arabino-furanoside(33), and l-linoleoylglycerol(34). One new compound was discovered(compound 1), 25 compounds were first isolated from R. aesculifolia, and 22 compounds were first isolated from the Rodgersia plant. The results indicated that compounds 22-24 possessed cytotoxicity for HepG2, MCF-7, HCT-116, BGC-823, and RAFLS cell lines(IC_(50) ranged from 5.89 µmol·L~(-1) to 20.5 µmol·L~(-1)). Compounds 8-14 and 30-32 showed good antioxidant capacity, and compound 9 showed the strongest antioxidant activity with IC_(50) of(2.00±0.12) µmol·L~(-1).

[Determination of polybrominated diphenyl ethers in marine sediments by composite chromatography column purification-gas chromatography-negative chemical ionization-mass spectrometry].

Polybrominated diphenyl ethers (PBDEs) are used as additive flame retardants. Because they lack the ability to form chemical bonds, PBDEs can easily enter the sediment environment. The accurate qualitative and quantitative analysis of PBDEs in sediments is of great importance for the accurate assessment of PBDE pollution in this environment. Sediments contain many impurities. Therefore, PBDEs in sediment should be purified before analysis to reduce the matrix effect. A method based on gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI/MS) was developed to determine 13 PBDEs in marine sediment samples using a column packed with deactivated silica gel, acidified silica gel, Florisil, and anhydrous sodium sulfate. Sediment samples were extracted by ultrasonication with a mixed solvent of n-hexane-dichloromethane (3∶1, v/v). After two cycles of ultrasonic extraction, the extract was purified by a composite chromatographic column and eluted with n-hexane-dichloromethane (3∶1, v/v). Thirteen PBDEs were determined by GC-NCI/MS in selected-ion monitoring (SIM) mode. The effects of different fillers, eluents, and elution volumes on the purification of PBDEs in the composite column were compared and analyzed, and the GC-NCI/MS analysis conditions were optimized. Three different packing columns were used to purify the sample extract. The first column was packed with 3 g of deactivated silica, 6 g of acidic silica, 3 g of deactivated silica, 3 g of Florisil, and 6 g of anhydrous sodium sulfate; the second column was packed with 3 g of Florisil, 3 g of deactivated silica, 6 g of acidic silica, 3 g of deactivated silica, and 6 g of anhydrous sodium sulfate; and the third column was packed with 3 g of deactivated silica, 6 g of acidified silica, 3 g of deactivated silica, and 6 g of anhydrous sodium sulfate. Among these columns, that packed with 3 g of deactivated silica, 6 g of acidic silica, 3 g of deactivated silica, 3 g of Florisil, and 6 g of anhydrous sodium sulfate showed the best purification effect. The 13 PBDEs showed good linearity in the mass concentration range of 0.1-20 µg/L with correlation coefficients (r2) greater than 0.995 (decabromodiphenyl oxide (BDE-209), r2>0.99). The limits of quantification (S/N=10) was 0.002-0.126 µg/kg. The average recoveries of the 13 PBDEs at three spiked levels of 0.2, 1.0, and 4.0 µg/kg were 85.3%-101.3%, 84.8%-113.6%, and 86.3%-94.7% with relative standard deviations of 4.4%-14.0%, 0.4%-4.9%, and 1.9%-6.6%, respectively. These findings indicate that the method has high sensitivity and accuracy as well as good precision. Finally, the method was applied to the analysis and detection of PBDEs in actual marine sediment samples. The results revealed that the sediment samples contained different contents of the 13 PBDEs, and high detection rates were obtained for lower-brominated PBDE homologs. The detection rate of bis(4-bromophenyl) ether (BDE-15) was 100%, and the detected content of BDE-209 was as high as 60.49 µg/kg. These results demonstrate that the developed method is suitable for the accurate qualitative and quantitative analysis of PBDEs in marine sediment samples.

Comparative study on removal of platinum cytostatic drugs at trace level by cysteine, diethylenetriamino functionalized Si-gels and polyethyleneimine functionalized sponge: Adsorption performance and mechanisms.

To efficiently remove trace Pt-based cytostatic drugs (Pt-CDs) from aqueous environments, a comparative investigation was conducted on the adsorption behavior of three commercial adsorbents including cysteine-functionalized silica gel (Si-Cys), 3-(diethylenetriamino) propyl-functionalized silica gel (Si-DETA) and open-celled cellulose MetalZorb® sponge (Sponge). The research on the adsorption of cisplatin and carboplatin encompasses investigations of pH dependence, adsorption kinetics, adsorption isotherms, and adsorption thermodynamics. The obtained results were compared with those of PtCl42- to better understand the adsorption mechanisms. The adsorption of cisplatin and carboplatin by Si-Cys was significantly better than Si-DETA and Sponge, which suggested that in chelation-dominated chemisorption, thiol groups provided high-affinity sites for Pt(II) complexation. Adsorption of the anion PtCl42- was more pH dependent and generally superior to that of cisplatin and carboplatin, benefiting from the contribution of ion association with protonated surfaces. The removal process of aqueous Pt(II) compounds occurred by the hydrolysis of complexes in solution and subsequent adsorption, and the specific adsorption process was explained by the synergistic action of ion association and chelation mechanisms. The rapid adsorption processes involving diffusion and chemisorption were well described by pseudo-second-order kinetic model. The isotherm studies suggested monolayer adsorption, consistent with the Langmuir model. Indicated from the adsorption enthalpy results, the chelation of cisplatin and carboplatin with thiol groups was an endothermic reaction, while the adsorption of PtCl42- was exothermic. At 343 K, Si-Cys achieved 98.5 ± 0.1 % (cisplatin) and 94.1 ± 0.1 % (carboplatin) removal. To validate the obtained findings, the described process was applied to urine samples doped with Pt-CDs as analog of hospital wastewaters and the removal was very efficient, ranging from 72 ± 1 % to 95 ± 1 %, when using Si-Cys as adsorbent, although limited matrix effects were observed.