A facile method for in situ fabrication of silica/cellulose aerogels and their application in CO2 capture.

Old corrugated containers-based cellulose and fly ash-based fresh wet silica gel were used as raw materials for in situ synthesis of a series of silica/cellulose aerogels in NaOH/urea solution. At a silicon to cellulose ratio of less than 2.5:1, the skeleton structure of the synthesized composite material was dominated by fibrils decorated with spherical silica nanoparticles. At a silicon to cellulose ratio of higher than 2.5:1, the skeleton structure of the composite material was dominated by spherical silica particles interspersed with cellulose. The synthesized composite material was applied to capture CO2 at ambient temperature and pressure. We observed that with increasing silicon content, the CO2 adsorption capacity of the composite material decreased (regardless of its dominant structure), while its selectivity for CO2/N2 increased. This work presents a facile method for the synthesis of adsorption material that has high capacity and selectivity for CO2.

CO2 capture performance and characterization of cellulose aerogels synthesized from old corrugated containers.

Old corrugated containers with low recyclability were used as raw materials to synthesize a series of aerogels with varying cellulose concentrations in NaOH/urea solution via a freeze-drying process. The resulting aerogels had a rich porous structure with specific surface areas in the range of 132.72-245.19 m2.g-1 and mesopore volumes in the range of 0.73-1.53 cm3.g-1, and were tested for CO2 sorption at ambient temperature and pressure, displaying excellent CO2 adsorption capacities in the range of 1.96-11.78 mmol.g-1. Furthermore, the CO2/N2 selectivity of aerogels decreased with decreasing specific surface area, which was mainly caused by the decrease in CO2 capture. In addition, the CO2 sorption capacity of the sample with 2% cellulose content, CA-2, exceeded the values reported so far for many other sorbents with higher specific surface areas, and showed reasonable cyclic stability for CO2 capture. Therefore, this adsorbent represents an attractive prospect for CO2 uptake at room temperature.

[Golgi phosphoprotein 3 overexpression inhibits paclitaxel-induced apoptosis in HeLa cells by promoting autophagy].

OBJECTIVE: To investigate the effect of Golgi phosphoprotein 3 (Golph3) on paclitaxel- induced apoptosis and autophagy in HeLa cells. METHODS: HeLa cells were transfected with a lentiviral vector expressing Golph3 or a small interfering RNA (siRNA) targeting Golph3 for up-regulation or down-regulation of Golph3 which was verified by Western blotting. The autophagic bodies in the cells were observed using transmission electron microscopy. The expression of autophagy markers p62 and LC3 were detected using Western blotting, and the cell apoptosis was examined by PI/Anexin V-FITC double staining and flow cytometry. The effects of blocking autophagy was evaluated by treatment of the cells with the autophagy inhibitor 3-MA. RESULTS: Transmission electron microscopy showed that the lentivirus-mediated overexpression of Golph3 significantly increased the number of autophagic bodies and interference of Golph3 expression significantly decreased autophagic bodies in HeLa cells. Western blotting showed that Golph3 overexpression caused an increased expression of LC3 and decreased the accumulation of p62 in the cells, and interference of Golph3 resulted in the reverse changes. The cell apoptosis induced by paclitaxel was significantly decreased in Golph3-overexpressing HeLa cells and increased in the cells with Golph3 knockdown (P>0.01). Treatment with 3-MA alone did not obviously affect HeLa cell apoptosis, but in cells with Golph3 knockdown, 3-MA significantly enhanced paclitaxel-induced apoptosis (P>0.01). CONCLUSIONS: Up-regulation of Golph3 promotes autophagy and inhibits paclitaxel-induced apoptosis, whereas suppression of Golph3 inhibits autophagy and enhances paclitaxel- induced apoptosis in HeLa cells.

Antidiarrhoeal mechanism study of fulvic acids based on molecular weight fractionation.

As the important component of humus, fulvic acids (FA) have a good antidiarrhoeal effect on animals and humans, and have been worldwide used in animal husbandry and even clinical practice for a long time. Due to the extremely complex chemical composition and structure of FA, the material basis and mechanism of its antidiarrhoeal activity have not been fully elucidated. In this study, we used ultrafiltration technique to fractionate this heterogeneous mixture into a series of relatively uniform fractions. The main structural features of FA and its fractions were characterized, and at the same time their antidiarrhoeal activities on drug-induced diarrhoea model mice were evaluated and the collagen content in the intestine of mice were determined. Through contrastive study of the relative variations between structure characteristics and antidiarrhoeal activities with the change of molecular weight, we found that the oxygen-containing functional groups especially phenolic hydroxyl groups, molecular weight distribution, colloidal properties and astringency were the material basis of the antidiarrhoeal activity. Fulvic acid substances had a dual antidiarrhoeal mechanism acting on the intestinal mucosa. The components with low molecular weight (< 5 K) mainly acted on the inside of intestinal mucosa and the components with high molecular weight (> 5 K) acted on the surface, and they could simultaneously exert the antidiarrhoeal effects.

Synthesis and characterization of magnetic dextran nanogel doped with iron oxide nanoparticles as magnetic resonance imaging probe.

Magnetic hybrid nanogels composed of magnetic nanoparticles and polymer hydrogel matrix have drawn much attention because of their unique superparamagnetic properties and biocompatibility as biomaterials. In this study, a facile method was developed for the preparation of iron oxide nanoparticle-loaded magnetic dextran nanogel as magnetic resonance imaging (MRI) probe. Water soluble superparamagnetic iron oxide nanocrystals (Fe3O4) was pre-synthesized and physically doped into a Schiff base-containing dextran nanogel formed using W/O microemulsion as nanoreactor. Magnetic dextran nanogel (Fe3O4@Dex) with particle size of 300-1000 nm was obtained with multiple Fe3O4 nanoparticles randomly encapsulated in the hydrogel networks. Magnetization and T2 relaxivity study shows that the resulted magnetic nanogel has similar superparamagneitc behaviors with single Fe3O4 nanocrystals, and relatively higher T2 relaxivity (277.2 mMFe-1·s-1) as MRI probe. Notably, Schiff base linkages and aldehyde groups on the dextran hydrogel matrix endow the magnetic nanogel with pH-sensitiveness and reactive groups for further modifications, which make the magnetic dextran nanogel a promising nanoplatform as MRI-guided drug delivery system with acid environment-responsiveness.

Solid-Waste-Derived Carbon Dioxide-Capturing Materials.

Solid sorbents are considered to be promising materials for carbon dioxide capture. In recent years, many studies have focused on the use of solid waste as carbon dioxide sorbents. The use of waste resources as carbon dioxide sorbents not only leads to the development of relatively low-cost materials, but also eliminates waste simultaneously. Different types of waste materials from biomass, industrial waste, household waste, and so forth were used as carbon dioxide sorbents with sufficient carbon dioxide capture capacities. Herein, progress on the development of carbon dioxide sorbents produced from waste materials is reviewed and covers key factors, such as the type of waste, preparation method, further modification method, carbon dioxide sorption performance, and kinetics studies. In addition, a new research direction for further study is proposed. It is hoped that this critical review will not merely sum up the major research directions in this field, but also provide significant suggestions for future work.

A novel magnetic MIL-101(Fe)/TiO2 composite for photo degradation of tetracycline under solar light.

A novel magnetic MIL-101(Fe)/TiO2 composite was synthesized for photo degradation of tetracycline (TC) under solar light. The composite was characterized by XRD, TGA, SEM, TEM, EDS, BET, FTIR, XPS, VSM, ESR, and PL. The resultant composite was environment friendly material, which exhibited high TC degradation efficiency and excellent reusability. In the meantime, it could be separated easily from TC solution by using magnet, which would save significant time and cost of preparation and degradation, having broad prospect in application. Using 1 g L-1 magnetic MIL-101(Fe)/TiO2 at pH = 7, 92.76% degradation efficiency was achieved under solar light irradiation in 10 min for 20 mg L-1 TC. Further experiments indicated that TiO2 introduced in the composite played an important role in the degradation process, which could be activated by the UV light in solar light to generate large amount of O2- and OH radicals. The degradation efficiency of TC in this paper was significantly higher than other research papers reported in last three years. This study put forward new magnetic Fe-based metal-organic frameworks (MOFs)/TiO2 composite for degrading pharmaceutical wastewater.

Magnetically separable and reusable rGO/Fe3O4 nanocomposites for the selective liquid phase oxidation of cyclohexene to 1,2-cyclohexane diol.

A series of magnetically separable rGO/Fe3O4 nanocomposites with various amounts of graphene oxide were successfully prepared by a simple ultrasonication assisted precipitation combined with a solvothermal method and their catalytic activity was evaluated for the selective liquid phase oxidation of cyclohexene using hydrogen peroxide as a green oxidant. The prepared materials were characterized using XRD, FTIR, FESEM, TEM, HRTEM, BET/BJH, XPS and VSM analysis. The presence of well crystallized Fe3O4 as the active iron species was seen in the crystal studies of the nanocomposites. The electron microscopy analysis indicated the fine surface dispersion of spherical Fe3O4 nanoparticles on the thin surface layers of partially-reduced graphene oxide (rGO) nanosheets. The decoration of Fe3O4 nanospheres on thin rGO layers was clearly observable in all of the nanocomposites. The XPS analysis was performed to evaluate the chemical states of the elements present in the samples. The surface area of the nanocomposites was increased significantly by increasing the amount of GO and the pore structures were effectively tuned by the amount of rGO in the nanocomposites. The magnetic saturation values of the nanocomposites were found to be sufficient for their efficient magnetic separation. The catalytic activity results show that the cyclohexene conversion reached 75.3% with a highest 1,2-cyclohexane diol selectivity of 81% over 5% rGO incorporated nanocomposite using H2O2 as the oxidant and acetonitrile as the solvent at 70 °C for 6 h. The reaction conditions were further optimized by changing the variables and a possible reaction mechanism was proposed. The enhanced catalytic activity of the nanocomposites for cyclohexene oxidation could be attributed to the fast accomplishment of the Fe2+/Fe3+ redox cycle in the composites due the sacrificial role of rGO and its synergistic effect with Fe3O4, originating from the conjugated network of π-electrons in its surface structure. The rapid and easy separation of the magnetic nanocomposites from the reaction mixture using an external magnet makes the present catalysts highly efficient for the reaction. Moreover, the catalyst retained its activity for five repeated runs without any drastic drop in the reactant conversion and product selectivity.

Liquid-liquid phase-change absorption of SO2 using N, N-dimethylcyclohexylamine as absorbent and liquid paraffin as solvent.

In the present work, liquid-liquid phase-change absorption of SO2 was investigated using N, N-dimethylcyclohexylamine (DMCHA) as an absorbent, and high boiling liquid paraffin (LP) as a solvent to reduce volatilization of the absorbent. The homogenous solution was split into two immiscible phases upon SO2 loading. The phase-change mechanism was attributed to the polarity variation of DMCHA before and after absorption by forming the charge-transfer complex DMCHA·SO2. The viscosity of the lower phase reached a maximum value of 24.5 mPa s at the absorption capacity of 1 mol SO2/mol DMCHA, and the viscosity of the corresponding upper phase was 46.4 mPa s. Both are lower than the reported viscosity of most ionic liquids. This solution exhibited extremely high mass selectivity of SO2/CO2 with a value of 626. The mass absorption capacity was founded to be 1.19 g SO2/g DMCHA at 1 atm, which is comparable with the highest reported mass absorption capacity. At low partial pressure, the absorption capacity still reached 0.78 g/g at 0.1 atm, 0.43 g/g at 0.02 atm and 0.27 g/g at 0.001 atm. Furthermore, DMCHA could be completely regenerated in 10 min via microwave heating. All the results indicated this phase-change solution is a promising candidate for SO2 capture.

CaO-based sorbent derived from lime mud and bauxite tailings for cyclic CO2 capture.

Using aluminum nitrate (AlN) and bauxite tailings (BTs) as different dopants, and lime mud (LM) as calcium source, a series of CaO-based sorbents were prepared for CO2 capture by dry mixing method; then, the carbonation conversions of multiple carbonation/calcination cycles were detected in a thermogravimetric analyzer (TGA). Effects of different dopants, dopant contents, precalcination conditions, and a long series of cycles on CO2 absorption properties were scrutinized, and the phase composition and morphologies were tested by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Durability studies show that the sample doped with AlN remains a higher absorption conversion (30.88%) after 30 carbonation/calcination cycles. In the meantime, the sorbent doped with BTs showed a lower conversion, which is probably resulted from the impurities from waste BTs. However, the sample BT has a better cyclic absorption stability. In addition, the incorporation of BTs, as a kind of solid waste, not only decreases the preparation cost but also is good for environment. The occurrence of Ca12Al14O33 phase is considered to provide a stable framework inhibiting inactivation of CaO, and improve the CO2 adsorption stability. Graphical abstract ᅟ.

Schiff base-containing dextran nanogel as pH-sensitive drug delivery system of doxorubicin: Synthesis and characterization.

Stimuli-responsive hydrogels have been widely researched as carrier systems, due to their excellent biocompatibility and responsiveness to external physiologic environment factors. In this study, dextran-based nanogel with covalently conjugated doxorubicin (DOX) was developed via Schiff base formation using the inverse microemulsion technique. Since the Schiff base linkages are acid-sensitive, drug release profile of the DOX-loaded nanogel would be pH-dependent. In vitro drug release studies confirmed that DOX was released much faster under acidic condition (pH 2.0, 5.0) than that at pH 7.4. Approximately 66, 28, and 9% of drug was released in 72 h at pH 2.0, 5.0, and 7.4, respectively. Cell uptake by the human breast cancer cell (MCF-7) demonstrated that the DOX-loaded dextran nanogel could be internalized through endocytosis and distributed in endocytic compartments inside tumor cells. These results indicated that the Schiff base-containing nanogel can serve as a pH-sensitive drug delivery system. And the presence of multiple aldehyde groups on the nanogel are available for further conjugations of targeting ligands or imaging probes.

Cellulosic Cr(salen) complex as an efficient and recyclable catalyst for copolymerization of SO2 with epoxide.

The search for green catalytic processes for the synthesis of useful polymers and incorporating the waste SO2 in highly-selective pathways become extremely important in the coming years. Herein, cellulose was modified by ethylenediamine, and then synthesized Schiff base with 3,5-di-tert-butyl-2-hydroxybenzaldehyde to immobilize chromium chloride and formed a novel heterogeneous cellulosic Cr(salen)-type catalyst for the first time. The cellulosic Cr(salen)-type catalyst shows high efficiency and recyclability in copolymerization of cyclohexene oxide with SO2. The influence factors such as the molar ratio of the catalyst and cyclohexene oxide, reaction temperature, and reaction time were researched in detail to study the optimal conditions. The copolymer product was characterized by FTIR and 1H NMR for confirming the structure. The possible copolymer mechanism is given, and we believed that the novel cellulosic Cr(salen)-type complex will be used as an efficient catalyst in other chemical reactions.

Synthesis and characterization of Schiff base contained dextran microgels in water-in-oil inverse microemulsion.

Polysaccharide-based microgels with high water content, excellent biocompatibility and controllable particle size have been widely studied as ideal candidates for drug release and delivery. In this study, microgels based on dextran were developed via the Schiff base formation between aldehyded dextran and ethylenediamine in a water-in-oil (W/O) microemulsion. Particle size of the resulted microgel was controllable between 800 and 1100nm by modulating the amount of the employed co-surfactants (Span 80/Tween 80). Furthermore, fluoresceins (e.g., aminofluorescein) and drugs (e.g., doxorubicin) with free amino groups can be conjugated onto the network of the dextran-based microgel via Schiff base linkages. Since the Schiff base linkages are degradable via hydrolysis and their stability decreases with the environmental pH decreases, the resulted Schiff bases contained microgel showed a pH dependent degradation profile. These results indicated that the pH-sensitive microgel based on dextran could be used as promising drug delivery systems for biomedical applications.

Development of sintering-resistant CaO-based sorbent derived from eggshells and bauxite tailings for cyclic CO2 capture.

Carbon dioxide, one of the major greenhouse gases, are believed to be a major contributor to global warming. As a consequence, it is imperative for us to control and remove CO2 emissions. The CaO, a kind of effective CO2 sorbent at high temperature, has attracted increasing attention due to some potential advantages. The main drawback in practical application is the deterioration of CO2 capture capacity following multiples cycles. In the present study, novel low-cost porous CaO-based sorbents with excellent CO2 absorption-desorption performance were synthesized using bauxite tailings (BTs) and eggshells as raw materials via solid-phase method. Effect of different BTs content on CO2 absorption-desorption properties was investigated. Phase composition and morphologies were analyzed by XRD and SEM, and CO2 absorption properties were investigated by the simultaneous thermogravimetric analyzer. The as-prepared CaO-based sorbent doped with 10 wt% BTs showed superior CO2 absorption stability during multiple absorption-desorption cycles, with being >55% conversion after 40 cycles. This improved CO2 absorption performance was attributed to the particular morphologies of the CaO-based sorbents. Additionally, during absorption-desorption cycles the occurrence of Ca12Al14O33 phase is considered to be responsible for the excellent CO2 absorption performance of CaO-based sorbents. In the meanwhile, the use of solid waste eggshell and BTs not only decreases the release of solid waste, but also moderates the greenhouse effect resulted from CO2.

Study of CO2 cyclic absorption stability of CaO-based sorbents derived from lime mud purified by sucrose method.

Using lime mud (LM) purified by sucrose method, derived from paper-making industry, as calcium precursor, and using mineral rejects-bauxite-tailings (BTs) from aluminum production as dopant, the CaO-based sorbents for high-temperature CO2 capture were prepared. Effects of BTs content, precalcining time, and temperature on CO2 cyclic absorption stability were illustrated. The cyclic carbonation behavior was investigated in a thermogravimetric analyzer (TGA). Phase composition and morphologies were analyzed by XRD and SEM. The results reflected that the as-synthesized CaO-based sorbent doped with 10 wt% BTs showed a superior CO2 cyclic absorption-desorption conversion during multiple cycles, with conversion being >38 % after 50 cycles. Occurrence of Ca12Al14O33 phase during precalcination was probably responsible for the excellent CO2 cyclic stability.