Showing papers in "Science China-chemistry in 2010"

Sorption of Eu(III) on GMZ bentonite in the absence/presence of humic acid studied by batch and XAFS techniques

Abstract: Bentonite has been extensively studied because of its strong sorption ability and low permeability. In this work, the Na-bentonite from Gaomiaozi County (China) has been characterized by XRD, FTIR and acid-base titration. The sorption of Eu(III) on Na-bentonite in the absence/presence of humic acid (HA) was studied at T = 25 ± 2 °C and in 0.01 mol/L NaClO4 solution. The effects of pH, HA, contact time and initial Eu(III) concentrations were also investigated. The results indicate that the sorption of Eu(III) on Na-bentonite was dependent on pH values. The presence of HA had little effect on Eu(III) sorption at low pH values, but decreased Eu(III) sorption at high pH values. X-ray absorption fine structure spectroscopy (XAFS) was applied to characterize the local structural environment of the adsorbed Eu(III) on bare Na-bentonite and HA-bentonite hybrids. The results indicate that Eu(III) was bound to O atoms at a distance of about 2.39 A at pH 4.15. The results are crucial for the evaluation of the sorption and migration of other trivalent lanthanides and actinides in bentonite as backfill materials.

Poly(ethylene glycol) conjugated nano-graphene oxide for photodynamic therapy

Abstract: A novel methoxy-poly(ethylene glycol) modified nano-graphene oxide (NGO-mPEG) was designed and synthesized as a photosensitizer (PS) carrier for photodynamic therapy of cancer. NGO with a size below 200 nm was prepared using a modified Hummers’ method. NGO was observed by AFM to exhibit a structure with single-layer graphene oxide sheets down to a few nanometers in height. Hydrophilic mPEG conjugation of NGO (NGO-mPEG) was found to enhance solubility in cell culture media. No apparent cytotoxicity of the NGO-mPEG was observed towards MCF-7 carcinoma cell line. Zinc phthalocyanine (ZnPc), a photosensitizer for photodynamic therapy, was loaded in the NGO-PEG through π-π stacking and hydrophobic interactions, with the drug loading efficiency up to 14 wt%. Hydrophobic ZnPc was internalized in MCF-7 cells, exhibiting a pronounced phototoxicity in the cells under Xe light irradiation. The results indicate a great potential of NGO-mPEG for photodynamic therapy of cancer.

Alkaline polymer electrolyte fuel cells: Principle, challenges, and recent progress

Abstract: Polymer electrolyte membrane fuel cells (PEMFC) have been recognized as a significant power source in future energy systems based on hydrogen. The current PEMFC technology features the employment of acidic polymer electrolytes which, albeit superior to electrolyte solutions, have intrinsically limited the catalysts to noble metals, fundamentally preventing PEMFC from widespread deployment. An effective solution to this problem is to develop fuel cells based on alkaline polymer electrolytes (APEFC), which not only enable the use of non-precious metal catalysts but also avoid the carbonate-precipitate issue which has been troubling the conventional alkaline fuel cells (AFC). This feature article introduces the principle of APEFC, the challenges, and our research progress, and focuses on strategies for developing key materials, including high-performance alkaline polyelectrolytes and stable non-precious metal catalysts. For alkaline polymer electrolytes, high ionic conductivity and satisfactory mechanical property are difficult to be balanced, therefore polymer cross-linking is an ultimate strategy. For non-precious metal catalysts, it is urgent to improve the catalytic activity and stability. New materials, such as transition-metal complexes, nitrogen-doped carbon nanotubes, and metal carbides, would become applicable in APEFC.

Selective separation of protein and saccharides by ionic liquids aqueous two-phase systems

Abstract: In the present work, it was found that aqueous solution of a hydrophilic ionic liquid (IL), 1-butyl-3-methylimidazolium dicyanamide ([C4mim][N(CN)2]), could be separated into an aqueous two-phase system (ATPS) by inorganic salts such as K2HPO4 and K3PO4. The top phase is IL-rich, while the bottom phase is phosphate-rich. It was shown that 82.7%–100% bovine serum albumin (BSA) could be enriched into the top phase and almost quantitative saccharides (arabinose, glucose, sucrose, raffinose or dextran) were preferentially extracted into the bottom phase in a single-step extraction by [C4mim][N(CN)2] + K2HPO4 ATPS. The extraction efficiency of BSA from the aqueous saccharide solutions was influenced by the molecular structure of saccharides. The conductivity, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were combined to investigate the microstructure of the IL-rich top phase and the possible mechanism for the selective separation. It is suggested that the formation of the IL aggregate and the IL aggregate-BSA complex plays a significant role in the separation of BSA from aqueous saccharide solutions. This is the first example for the selective separation by ILs-based ATPSs. It is expected that these findings would have potential applications in bio-analysis, separation, and IL recycle.

Using FTIR spectroscopy to detect sericin on historic silk

Abstract: Silks represent some of the most precious ancient and historic textile artefacts in collections worldwide Their optimum preservation demands an appreciation of their characteristics One important concern, especially with regard to ancient Chinese silks, is whether the fabrics have been degummed Silks with remnant sericin gum coating the fibroin fibres would require different conservation protocol In previous research on aged silks, the presence of sericin has been inferred from amino acid analysis of hydrolysates In the study reported here, the potential of FTIR spectroscopy to provide a simpler and rapid method of detecting sericin on silk has been investigated Both fibroin and sericin exhibit singular IR absorptions Attenuated total reflectance spectroscopy was found to highlight the sericin coating more effectively than transmission and reflectance spectroscopy Three particular peak intensity ratios were identified which might provide a quantitative estimate of the sericin content of new silk, to a sensitivity of 1%–2% These were also shown to be valid indicators for the presence of sericin on artificially aged and archaeological silks, although quantitation was now not possible Besides the peak intensity ratios, two signature peaks were also seen to be useful markers for silk fibroin, and their presence in a spectrum could be used to infer a degummed silk

Electrospinning of ultrafine core/shell fibers for biomedical applications

Abstract: Because of the inherent appearance similar to the natural extracellular matrix, ultrafine fibrous membranes prepared via electrospinning exhibit widespread applications, especially in the biomedical area. Extensional modifications of coaxial and emulsion electrospinning have drawn much attention in preparation of core/shell fibers for applications as tissue engineering scaffolds and controlled delivery systems for bioactive substances. Due to incorporation of multi-components in the electrospun core/shell fibers, the process of coaxial and emulsion electrospinning became more susceptible. The theories have not been fully understood. A series of investigations were carried out evaluating the systematic and processing parameters. This paper reviews advantages and potentials of electrospun core/shell fibers as well as factors influencing their formation on the basis of our research and new progress.

Stimulus-responsive polymeric nanoparticles for biomedical applications

Abstract: Polymeric nanoparticles with unique properties are regarded as the most promising materials for biomedical applications including drug delivery and in vitro/in vivo imaging. Among them, stimulus-responsive polymeric nanoparticles, usually termed as “intelligent” nanoparticles, could undergo structure, shape, and property changes after being exposed to external signals including pH, temperature, magnetic field, and light, which could be used to modulate the macroscopical behavior of the nanoparticles. This paper reviews the recent progress in stimulus-responsive nanoparticles used for drug delivery and in vitro/in vivo imaging, with an emphasis on double/multiple stimulus-responsive systems and their biomedical applications.

Isolation and identification of bacteria responsible for simultaneous anaerobic ammonium and sulfate removal

Abstract: Sulfate-dependent anaerobic ammonium oxidation is a novel biological reaction, in which ammonium is oxidized with sulfate as the electron acceptor under anoxic conditions. Ammonium and sulfate are cosmopolitan chemical species which are an integral part of the global nitrogen and sulfur cycles. A detailed exploration of sulfate-dependent anaerobic ammonium oxidation is quite practical. In this work, a bacterial strain named ASR has been isolated from an anaerobic ammonia and sulfate removing reactor working under steady-state. On the basis of electron microscopy, physiological tests and 16S rDNA phylogenetic sequence analysis, the strain ASR is found to be related to Bacillus benzoevorans. According to the biological carbon source utilization test, the strain ASR could use many carbon sources. Its optimum pH value and temperature were 8.5 and 30 °C, respectively. The test proves that the strain ASR is able to use sulfate to oxidize ammonia anaerobically. The maximum ammonia and sulfate removal rates were 44.4% and 40.0%, respectively. The present study provided biological evidence for the confirmation and development of sulfate-dependent anaerobic ammonium oxidation and brought new insights into the global nitrogen and sulfur cycles.

Highly regio- and stereo-selective copolymerization of CO 2 with racemic propylene oxide catalyzed by unsymmetrical ( S,S,S )-salenCo(III) complexes

Abstract: A novel unsymmetrical (S,S,S)-salen ligand bearing a derived chiral-BINOL was synthesized by the reaction of the condensation product of (1S,2S)-1,2-diaminocyclohexane mono(hydrogen chloride) with 3-adamanyl-5-tert-butyl-2-hydroxybenzaldehyde and 3-formoyl-2-hydroxy-2′-alkyloxy-1,1′-binaphthyl, which originated from (S)-1,1′-bi-2-naphthol via a four-step reaction. The cobalt complexes of this ligand, in conjunction with a nucleophilic cocatalyst, exhibited excellent activity in catalyzing asymmetric, regio- and stereo-selective copolymerization of CO2 and racemic propylene oxide. The highest record of kinetic resolution coefficient (Krel) was obtained with the use of binary catalyst system consisting of (S,S,S)-salenCo(III) complex 1c and bulky bis(triphenylphosphine)-iminium chloride (PPNCl). The resulting poly(propylene carbonate)s have more than 99% carbonate linkages and more than 98% head-to-tail content.

Cobalt, a reactive metal in releasing hydrogen from sodium borohydride by hydrolysis: A short review and a research perspective

Abstract: Cobalt is commonly admitted as being a promising catalyst in accelerating NaBH4 hydrolysis, being as reactive as noble metals and much more cost-effective. This is the topic of the present paper. Herein, we survey (i) the NaBH4-devoted literature while especially focusing on the Co catalysts and (ii) our work on the same topic. Finally, we report (iii) reactivity results of newly developed Co-based catalysts. From both surveys, it mainly stands out that Co has been investigated as catalysts in various forms: namely, as chlorides, reduced nanoparticles (metal Co, Co boride, Co-B alloy), supported over supports and shaped. In doing so the reactivity can be easily varied achieving H2 generation rates from few to >1000 L(H2)/min·g (metal). Nevertheless, our work can be distinguished from the NaBH4 literature. Indeed, we are working on strategies that focus on making alternative Co-based catalysts. One of these strategies is illustrated here as we report new reactivity data of Co-based bimetallic supported catalysts. For example, we show that 20 wt% Co90Y10/γAl2O3-20 wt% Co95Hf5/γAl2O3 > 20 wt% Co99Zr1/γAl2O3 > 20 wt% Co/γAl2O3, the best catalysts showing HGRs of about 245 mL(H2)/min or 123 L(H2)/min·g (metals).

New-generation biomedical materials: Peptide dendrimers and their application in biomedicine

Abstract: Peptide dendrimers are attractive synthetic polymers and have been widely used as a new generation of biomaterials in recent years. Peptide dendrimers, as well as general dendrimers, may be synthesized to reach nano sizes, and display well-defined architectures, highly-branched structures, high density of functional terminal groups, and controllable molecular weights. On the other hand, peptide dendrimers have properties similar to proteins and some special characteristics, such as good biocompatibility, water solubility and resistance to proteolytic digestion. Due to these advantages, peptide dendrimers have received considerable attention in biomedicine. This review focuses on the development of peptide dendrimers with emphasis on their applications both in diagnostics and in therapy.

Regional ozone pollution and key controlling factors of photochemical ozone production in Pearl River Delta during summer time

Abstract: An intensive field campaign including measurements from the environmental monitoring network and from two super sites took place in the Pearl River Delta region in summer 2006. Using routinely measured O3 and NOx concentrations, the spatial and temporal variation of O3 and of the total oxidant concentrations was characterized. According to the spatial variability of NO2/NO, the two super sites were found to be representative of polluted urban and downwind suburban conditions. In addition, both sites were located in high O3 regions. In-depth diagnostic of photochemical ozone production processes and their key controlling factors are achieved with an observation-based model (OBM) to gain regional perspectives. Budget analysis and sensitivity model runs show that aldehyde and HONO chemistry had significant impacts on local photochemical ozone production rates. The analysis of calculated Relative Incremental Reactivities shows that photochemical ozone production rates are mainly sensitive to anthropogenic hydrocarbons (HCs) in the polluted urban areas. In the suburban areas, sensitivity to nitrogen oxide (NO) concentrations dominated. Key anthropogenic HCs in both areas are alkenes and aromatics. Significant differences of ozone production efficiencies are identified between the urban and suburban regions, consistent with the OBM diagnosed results.

Heterogeneous reaction of SO2 on TiO2 particles

Abstract: The heterogeneous reaction of SO2 on TiO2 particles was studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The influences of the oxygen concentration, relative humidity (RH), and ultraviolet (UV) light illumination (λ ≈ 365 nm) intensity on the reaction were investigated. The main product of the heterogeneous reaction of SO2 on TiO2 particles was sulfate with UV illumination and sulfite without it. The production of sulfate was promoted significantly with UV illumination or water, and there was a synergistic effect when both were present. In the dry system without UV, the heterogeneous reaction of SO2 on TiO2 particles was found to be second-order for SO2 and the initial uptake coefficient, γBET, was determined to be 1.94 × 10−6. With UV and RH = 40%, the reaction order was first-order and the initial uptake coefficient was 1.35 × 10−5.

Kumada chain-growth polycondensation as a universal method for synthesis of well-defined conjugated polymers

Abstract: Kumada chain-growth polycondensation (KCGP) is a novel method for the synthesis of well-defined conjugated polymers. Because the Ni-catalyst can transfer in an intramolecular process to the propagating chain end, the polymerization follows chain-growth mechanism. With this newly developed method, various conjugated polymers, such as polythiophenes, poly(p-phenylene) (PPP), polypyrrole (PPy), and polyfluorene with controlled molecular weights and relatively narrow polydispersities (PDIs), have been prepared. Especially, the polymerizations for poly(3-alkylthiophene)s (P3ATs), PPP, and PPy exhibited quasi-living characteristics, which allows preparing polymer brushes, fully-conjugated block copolymers, and macroinitiators and macro-reactants for the synthesis of rod-coil block copolymers. In the current review, the progress in this new area is summarized.

Molecular hosts for triplet emitters in organic light-emitting diodes and the corresponding working principle

Abstract: This paper summarizes the mechanism and routes for excitation of triplet emitters in dopant emission based phosphorescent organic light-emitting diodes (PhOLEDs), providing a comprehensive overview of recent progress in molecular hosts for triplet emitters in PhOLEDs. Particularly, based on the nature of different hosts, e.g., hole transporting, electron transporting or bipolar materials, in which the dopant emitters can be hosted to generate phosphorescence, the respective device performances are summarized and compared. Highlights are given to the relationships among the molecular structure, thermal stability, triplet energy, carrier mobility, molecular orbital energy level and their corresponding device performances.

Advances in the study of current-use non-PBDE brominated flame retardants and dechlorane plus in the environment and humans

Abstract: The fate of the high production volume, currently in use, and not regulated non-polybrominated diphenyl ether (PBDE) flame retardants, such as tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD) and dechlorane plus (DP), and the alternative flame retardants of PBDE, such as BTBPE and DBDPE, in the environment has attracted increasing attention and aroused concern due to the increasing regulation and phasing-out of PBDEs. This paper reviews the distribution, bioaccumulation, human exposure and environmental behavior of those non-PBDE flame retardants in various environmental compartments. The data gaps and needs for future research are discussed.

Enhancing the response of CALUX and CAFLUX cell bioassays for quantitative detection of dioxin-like compounds.

Abstract: Reporter genes produce a protein product in transfected cells that can be easily measured in intact or lysed cells and they have been extensively used in numerous basic and applied research applications. Over the past 10 years, reporter gene assays have been widely accepted and used for analysis of 2,3,7,8-tetrachlorodibenzo-p-dioxin and related dioxin-like compounds in various types of matrices, such as biological, environmental, food and feed samples, given that high-resolution instrumental analysis techniques are impractical for large-scale screening analysis. The most sensitive cell-based reporter gene bioassay systems developed are the mechanism-based CALUX (Chemically Activated Luciferase Expression) and CAFLUX (Chemically Activated Fluorescent Expression) bioassays, which utilize recombinant cell lines containing stably transfected dioxin (AhR)-responsive firefly luciferase or enhanced green fluorescent protein (EGFP) reporter genes, respectively. While the current CALUX and CAFLUX bioassays are very sensitive, increasing their lower limit of sensitivity, magnitude of response and dynamic range for chemical detection would significantly increase their utility, particularly for those samples that contain low levels of dioxin-like HAHs (i.e., serum). In this study, we report that the addition of modulators of cell signaling pathways or modification of cell culture conditions results in significant improvement in the magnitude and overall responsiveness of the existing CALUX and CAFLUX cell bioassays.

Synthesis of Fe3O4@SiO2@polymer nanoparticles for controlled drug release

Abstract: Novel multifunctional nanoparticles containing a magnetic Fe3O4@SiO2 sphere and a biocompatible block copolymer poly(ethylene glycol)-b-poly(aspartate) (PEG-b-PAsp) were prepared. The silica coated on the superparamagnetic core was able to achieve a magnetic dispersivity, as well as to protect Fe3O4 against oxidation and acid corrosion. The PAsp block was grafted to the surface of Fe3O4@SiO2 nanoparticles by amido bonds, and the PEG block formed the outermost shell. The anticancer agent doxorubicin (DOX) was loaded into the hybrid nanoparticles via an electrostatic interaction between DOX and PAsp. The release rate of DOX could be adjusted by the pH value.

Immobilization of acetylcholinesterase on one-dimensional gold nanoparticles for detection of organophosphorous insecticides

Abstract: This paper reports a simple method for immobilization of acetylcholinesterase (AChE) on one-dimensional (1D) gold (Au) nanoparticles for detection of organophosphorous (OP) insecticides. 1D Au nanoparticles were prepared by electrodeposition in the pores of an alumina template which was subsequently removed by 2.0 M NaOH solution. They were characterized by XRD and FESEM. The immobilized AChE retained its biological activity and catalyzed the hydrolysis of acetylthiocholine to form thiocholine, which was subsequently oxidized to produce detectable signals. Based on the inhibition toward the enzymatic activity of AChE by OP insecticides, sensitive detection of methamidophos (an OP insecticide) was performed. Under optimal conditions, the sensors could be used for the determination of methamidophos ranging from 0.004 to 24 μg/mL with the detection limit of 0.001 μg/mL. The developed OP insecticide biosensors exhibited satisfactory stability and reproducibility. This work demonstrated that 1D Au nanoparticles could serve as an ideal carrier for immobilization of AChE to fabricate the corresponding biosensor.

Cellulose conversion to polyols on supported Ru catalysts in aqueous basic solution

Abstract: It is of great significance and challenge to achieve direct conversion of cellulose to specific polyols, eg, ethylene glycol and propylene glycol For such selective conversion, a novel one-pot approach was studied by combination of alkaline hydrolysis and hydrogenation on supported Ru catalysts A wide range of bases including solid bases, eg, Ca(OH)2 and La2O3, and phosphate buffers were examined in the cellulose reaction in water, and the cellulose conversions and polyol products depended largely on the basicity or pH values in the aqueous solutions Ethylene glycol, 1,2-propanediol, and especially 1,2,5-pentanetriol were obtained with selectivities of 15%, 14% and 22%, respectively, at 38% cellulose conversion at pH 8 in phosphate buffer solution These preliminary results provide potentials for efficient conversion of cellulose to targeted polyols by using the advantages of bases

Bioreducible unimolecular micelles based on amphiphilic multiarm hyperbranched copolymers for triggered drug release

Abstract: A novel type of bioreducible amphiphilic multiarm hyperbranched copolymer (H40-star-PLA-SS-PEG) based on Boltorn® H40 core, poly(l-lactide) (PLA) inner-shell, and poly(ethylene glycol) (PEG) outer-shell with disulfide-linkages between the hydrophobic and hydrophilic moieties was developed as unimolecular micelles for controlled drug release triggered by reduction The obtained H40-star-PLA-SS-PEG was characterized in detail by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), gel permeation chromatography (GPC), differential scanning calorimeter (DSC), and thermal gravimetric analysis (TGA) Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analyses suggested that H40-star-PLA-SS-PEG formed stable unimolecular micelles in aqueous solution with an average diameter of 19 nm Interestingly, these micelles aggregated into large particles rapidly in response to 10 mM dithiothreitol (DTT), most likely due to shedding of the hydrophilic PEG outer-shell through reductive cleavage of the disulfide bonds As a hydrophobic anticancer model drug, doxorubicin (DOX) was encapsulated into these reductive unimolecular micelles In vitro release studies revealed that under the reduction-stimulus, the detachment of PEG outer-shell in DOX-loaded micelles resulted in a rapid drug release Flow cytometry and confocal laser scanning microscopy (CLSM) measurements indicated that these DOX-loaded micelles were easily internalized by living cells Methyl tetrazolium (MTT) assay demonstrated a markedly enhanced drug efficacy of DOX-loaded H40-star-PLA-SS-PEG micelles as compared to free DOX All of these results show that these bioreducible unimolecular micelles are promising carriers for the triggered intracellular delivery of hydrophobic anticancer drugs

Levels, trends and risk assessment of arsenic pollution in Yangzonghai Lake, Yunnan Province, China

Abstract: The arsenic contamination accident in Yangzonghai Lake, Yunnan has been of wide concern. In order to investigate the arsenic distribution and concentration trends after the accident, samples including lake water, sediments, soil, aquatic organisms and crops were collected in November 2008, as well as in February, May and September 2009. The average arsenic concentrations (arithmetic average) in lake water in the four sampling events were 176.9, 147.3, 159.3, and 161.1 μg/L, while those in the sediments were 32.87, 62.41, 62.99, and 46.96 μg/g, respectively. The highest content of total arsenic in soil in the vicinity of Yangzonghai was 23.33 μg/g, which was below the limits of the relevant national standard. The total arsenic levels in most aquatic plants were in the range of 100–200 μg/g, with Vallisneria natans (Lour.) Hara having the highest concentration of ∼300 μg/g. The arsenic levels of fish and shrimps were in the range of 1.52–11.4 μg/g (dry weight).

Heterogeneous reaction of formaldehyde on the surface of TiO2 particles

Abstract: The heterogeneous reaction of formaldehyde (HCHO) on the surface of titanium dioxide (TiO2) was investigated in situ using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) combined with ion chromatography (IC), X-ray diffraction (XRD), and transmission electron microscopy (TEM). Formate, dioxymethylene, methoxy, and polyoxymethylene were observed in the infrared spectra of TiO2 particles during the reaction. On the surface of TiO2, the adsorbed HCHO was first oxidized to dioxymethylene and further oxidized to formate. The effects of temperature and ultraviolet radiation (UV) on the reaction products and reactive uptake coefficients were studied, and the results indicate that the reaction rate can be accelerated at increasing temperatures as well as under UV. The heterogeneous reaction mechanisms of HCHO on the surface of TiO2 in the dark and under UV irradiation are proposed. Kinetic measurements show that formate formation on TiO2 is second order in HCHO concentration and the initial reactive uptake coefficients at room temperature calculated with the Brunauer-Emmett- Teller specific surface area are (0.5–5) × 10−8 ([HCHO]: 1 × 1013−2 × 1014 molecules/cm3). A linear function relationship exists between the uptake coefficient and the concentration. The apparent activation energy of the reaction was also determined.

Size and support effects for CO oxidation on supported Pd catalysts

Abstract: National Natural Science Foundation of China [20873109]; National Basic Research Program of China (973 program) [2005CB221401, 2010CB732303]; Chinese Ministry of Education [309019]; Ph.D. Programs Foundation of Chinese Ministry of Education [200803841011]; Natural Science Foundation of Fujian Province, China [2008J0168]

Fullerenes as unique nanopharmaceuticals for disease treatment

Abstract: As unique nanoparticles, fullerenes have attracted much attention due to their unparalleled physical, chemical and biological properties. Various functionalized fullerenes with -OH, -NH2, -COOH, and peptide modifications were developed. It summarized the biological activities of fullerenes derivatives in cancer therapy with high efficiency and low toxicity, as reactive oxygen species scavenger and lipid peroxidation inhibitor, to inhibit human immunodeficiency virus and to suppress bacteria and microbial at low concentration. In addition, the mechanism for fullerene to enter cells and biodistribution of fullerene in vivo was also discussed. This research focuses on the current understanding of fullerenes-based nanomaterials in the potential clinical application as well as biological mechanism of fullerenes and its derivatives in disease therapy.

First-principles calculation of core-level binding energy shift in surface chemical processes

Abstract: Combined with third generation synchrotron radiation light sources, X-ray photoelectron spectroscopy (XPS) with higher energy resolution, brilliance, enhanced surface sensitivity and photoemission cross section in real time found extensive applications in solid-gas interface chemistry. This paper reports the calculation of the core-level binding energy shifts (CLS) using the first-principles density functional theory. The interplay between the CLS calculations and XPS measurements to uncover the structures, adsorption sites and chemical reactions in complex surface chemical processes are highlight. Its application on clean low index (111) and vicinal transition metal surfaces, molecular adsorption in terms of sites and configuration, and reaction kinetics are domonstrated.

Optimal paths for a light-driven engine with a linear phenomenological heat transfer law

Abstract: An irreversible light-driven engine is described in this paper, in which the heat transfer between the working fluid and the environment obeys a linear phenomenological heat transfer law [q ∝ Δ(T −1)], with a working fluid composed of the bimolecular reacting system 2SO3FaiS2O6F2. Piston trajectories maximizing work output and minimizing entropy generation are determined for such an engine with rate-dependent loss mechanisms of friction and heat leakage. The optimal control theory is applied to determine the optimal configurations of the piston motion trajectory and the fluid temperature. Numerical examples for the optimal configuration are provided, and the obtained results are compared with those derived with Newtonian heat transfer law [q ∝ Δ(T)].

Carbohydrate biomarkers for future disease detection and treatment.

Abstract: Carbohydrates are considered as one of the most important classes of biomarkers for cell types, disease states, protein functions, and developmental states. Carbohydrate “binders” that can specifically recognize a carbohydrate biomarker can be used for developing novel types of site specific delivery methods and imaging agents. In this review, we present selected examples of important carbohydrate biomarkers and how they can be targeted for the development of therapeutic and diagnostic agents. Examples are arranged based on disease categories including (1) infectious diseases, (2) cancer, (3) inflammation and immune responses, (4) signal transduction, (5) stem cell transformation, (6) embryo development, and (7) cardiovascular diseases, though some issues cross therapeutic boundaries.

A novel ionic liquids-based scrubbing process for efficient CO2 capture

Abstract: A novel alkanolamine-based ionic liquid, N-methyl-diethanolammonium tetrafluoroborate ([MDEA][BF4]), was synthesized in our laboratory. The ionic liquid-based composite solution consisting of N-methyl-diethanolamine (MDEA), [MDEA][BF4], piperazine (PZ) and H2O was investigated for CO2 capture. The optimal performance for CO2 capture was found at 45 °C, 1.50 MPa, probably due to a synergistic action of the reaction and the transport. No apparent corrosion was found on stainless and carbon steel with the above composite solution. This finding is very significant to the promotion of its engineering application.

Kinetic studies of gas hydrate formation with low-dosage hydrate inhibitors

Abstract: Pipeline blockage by gas hydrates is a serious problem in the petroleum industry. Low-dosage inhibitors have been developed for its cost-effective and environmentally acceptable characteristics. In a 1.072-L reactor with methane, ethane and propane gas mixture under the pressure of about 8.5 MPa at 4 A degrees C, hydrate formation was investigated with low-dosage hydrate inhibitors PVP and GHI1, the change of the compressibility factor and gas composition in the gas phase was analyzed, the gas contents in hydrates were compared with PVP and GHI1 added, and the inhibition mechanism of GHI1 was discussed. The results show that PVP and GHI1 could effectively inhibit the growth of gas hydrates but not nucleation. Under the experimental condition with PVP added, methane and ethane occupied the small cavities of the hydrate crystal unit and the ability of ethane entering into hydrate cavities was weaker than that of methane. GHI1 could effectively inhibit molecules which could more readily form hydrates. The ether and hydroxy group of diethylene glycol monobutyl ether have the responsibility for stronger inhibition ability of GHI1 than PVP.