[Show abstract][Hide abstract] ABSTRACT: The facile synthesis of three-dimensionally ordered macroporous (3DOM) γ-alumina with high thermal stability and the performance test in hydrodesulfurization (HDS) of dibenzothiophene (DBT) were investigated. The synthesis strategy in this work is based on a sol–gel process using a colloidal crystal template method in which a triblock copolymer F127 is employed as the mesoporous structure-directing agent. The as-prepared samples were characterized by means of techniques such as thermogravimetric analysis, XRD measurement, nitrogen adsorption and desorption, SEM and TEM investigations. These results showed that all the synthesized alumina samples possess a highly ordered macroporous structure. The sample calcined at 800 °C with a surface area of 79 m2 g−1 exhibited the ordered mesopores within the walls of the macroporous cages. The co-existence of the interconnected macroporous and mesoporous structure of the prepared γ-alumina enables it to be an effective catalyst support with favorable access
Microporous and Mesoporous Materials 08/2012; 158:1-6. · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Here we show that the introduction of N into a carbon surface facilitates the hydrogen-bonding interactions between the carbon surface and CO2 molecules, which accounts for the superior CO2 uptake of the N-doped activated carbons. This new finding challenges the long-held viewpoint that acid–base interactions between N-containing basic functional groups and acidic CO2 gas are responsible for the enhanced CO2 capture capacity of N-doped carbons.
Energy & Environmental Science 05/2012; 5(6):7323-7327. · 11.65 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Several SBA-15 silica materials with different pore structures were synthesized and functionalized with poly(ethyleneimine) (PEI). The as-prepared materials were characterized by XRD, SEM, TG, FT-IR, and N2 physisorption techniques followed by testing for CO2 capture using a N2 stream containing 15.1 v/v% CO2 in the temperature range of 30−75 °C. The results showed that the CO2 adsorption capacity linearly increased with the total pore volume of the SBA-15 phases in the tested temperature range (R2 > 0.94). Temperature also showed a strong influence on CO2 adsorption capacity. SBA-15 material with the largest pore volume (1.14 cm3 g−1) exhibited the largest CO2 adsorption capacity (105.2 mg g−1 adsorbent) with 15.1 v/v% CO2 in N2 at 75 °C and atmospheric pressure. Pore size was found not to be the main factor influencing the CO2 adsorption capacity of these PEI-modified SBA-15 materials. Adsorption−desorption cycles (12) revealed that the adsorbents with PEI loaded inside the pore channels were found to be quite stable, as they retained their CO2 adsorption capacity with many cycles.
[Show abstract][Hide abstract] ABSTRACT: Three mesocellular silica foam (MCF) materials with different window sizes were prepared and functionalized with polyethyleneimine (PEI) for use as CO2 adsorbents. The as-prepared adsorbents were characterized by XRD, TEM, SEM, nitrogen adsorption/desorption and thermogravimetric (TG) analyses. CO2 capture was performed in a fixed bed reactor operated at atmospheric pressure. The results showed that the CO2 adsorption capacity increased with the window size of the MCF substrates. MCF material that had the largest window size exhibited the largest CO2 uptake of 152.0 mg/g of adsorbent (304.0 mg/g of PEI) with a 50 wt% PEI loading under the conditions of 15.1% (v/v) CO2 in N2 at 75 °C and atmospheric pressure. It is one of the highest capture capacities per gram of PEI reported in the literature thus far under the above conditions used. Repeated adsorption/desorption cycles revealed that the MCF modified by PEI is a good adsorbent for CO2 with good cyclic stability.
Chemical Engineering Journal. 01/2011; 168(2):918-924.
[Show abstract][Hide abstract] ABSTRACT: We report the synthesis of carbon nanotubes (CNTs)/mesostructured silica core-shell nanowires via an interfacial surfactant templating approach. The nanowires possess perpendicularly aligned and uniform accessible mesopores, high surface area and large pore volume. When dimethyl sulfoxide reductase (DMSOR) enzyme is immobilized on the core-shell nanowires, the complex can enhance the electrical communication between the active sites of the enzyme and the electrode surface in the presence of a mediator. The unique properties of the CNTs and the uniform accessible mesopores of the nanowires have made this material promising in the applications as carbon nanotubes field-effect transistors, electrochemical detection, and biosensors.
[Show abstract][Hide abstract] ABSTRACT: A highly active catalyst (La0.7Ag0.3MnO3) for simultaneous removal of nitrogen oxides (NOx) and diesel soot is synthesized by solid state method and the catalyst is characterized by XRD, FT-IR, H2-TPR, and O2-TPD. The results indicate that metallic Ag appears in the La0.7Ag0.3MnO3 catalyst. The concentration of oxygen vacancy and the over-stoichiometry oxygen content also remarkably increase as the substitution increase of Ag+ for La3+ at A-site ions. The simultaneous removal of soot particulates and NOx activities are evaluated by a temperature-programmed reaction (TPRe) technique. The superior performance of the La0.7Ag0.3MnO3 catalyst for the reaction is probably due to lots of oxygen vacancy and over-stoichiometry oxygen in the perovskite lattice along with the zero-valence silver.
[Show abstract][Hide abstract] ABSTRACT: Schistosoma japonicum is a parasitic flatworm that causes human schistosomiasis, which is a significant cause of morbidity in China and the Philippines. Here we present a draft genomic sequence for the worm. The genome provides a global insight into the molecular architecture and host interaction of this complex metazoan pathogen, revealing that it can exploit host nutrients, neuroendocrine hormones and signalling pathways for growth, development and maturation. Having a complex nervous system and a well-developed sensory system, S. japonicum can accept stimulation of the corresponding ligands as a physiological response to different environments, such as fresh water or the tissues of its intermediate and mammalian hosts. Numerous proteases, including cercarial elastase, are implicated in mammalian skin penetration and haemoglobin degradation. The genomic information will serve as a valuable platform to facilitate development of new interventions for schistosomiasis control. Schistosomiasis is an ancient scourge of mankind, depicted graphically in papyri from Pharaonic Egypt and known from human remains over 2,000 years old from China 1,2 . Blood-dwelling trematodes (phylum Platyhelminthes) of the genus Schistosoma cause this chronic and debilitating disease, which afflicts more than 200 million people in 76 tropical and subtropical countries. Morbidity is high and schistoso-miasis contributes to several hundreds of thousands of deaths annually 3–5 . Three principal species can infect humans: Schistosoma japonicum, Schistosoma mansoni and Schistosoma haematobium. The first of these is prevalent in the Philippines and parts of Indonesia, and is a major disease risk for 66 million people living in southern China 2 . It remains a major public health concern in China despite over 50 years of concerted campaigns for its control 2,6 . Approximately one million people in China, and more than 1.7 million bovines and other mammals, are currently infected 2 . Control measures include community-based praziquantel chemotherapy, health education, improved sanitation, environmental modification and snail control. However, additional approaches, such as the development and deploy-ment of new drugs and anti-schistosome vaccines are urgently needed to meet the prevailing challenges, which include the spectre of praziquantel-resistant parasites 7,8 . During their complex developmental cycle, schistosomes alternate between a mammalian host and a snail host through the medium of fresh water. After burrowing out of the snail host, free-swimming cercariae penetrate the skin of the mammalian host, travel through the blood to the liver via the lungs, and transform into schistosomula. These mature in the hepatic portal vein, mate and, in the case of S. japonicum, migrate to their final destination in the mesenteric venous plexus. Female worms release thousands of eggs daily, which are discharged in the faeces after a damaging passage through the intestinal wall. If they reach fresh water, eggs hatch to release free-swimming ciliated miracidia, which, guided by light and chemical stimuli, seek amphibious snails of the genus Oncomelania. Within the hemocoel of the snail, miracidia give rise asexually to numbers of sporocysts, in which further asexual propagation produces numerous cercariae. Eggs deposited by adult female schistosomes embolize in the liver, intestines and other tissue sites and are the key contributors to the pathology and associated morbidity of schistosomiasis. Notably, the highly adapted relationship between schistosomes and their snail intermediate and mammalian definitive hosts appears to involve exploitation by the parasite of host endocrine and immune signals 9,10 . The evasion strategies that underpin avoidance of the host immune system, allowing schistosomes to survive for years despite strong host immune responses, have long interested investigators intent on development of an efficacious vaccine. Unlike most other platyhelminths, schistosomes are dioecious. The genome is arrayed on eight pairs of chromosomes, seven pairs of autosomes and one pair of sex chromosomes. Females are the heterogametic sex (ZW); males are homogametic (ZZ) 11,12 . No other lophotrochozoan 13 has yet been sequenced.
[Show abstract][Hide abstract] ABSTRACT: Sandwiched film of MnO2 nanosheet (MONS) and multi-walled carbon nanotube (MWCNT) was assembled by using the layer-by-layer method, based on electrostatic interaction of positively-charged poly (diallyl dimethyl ammonium chloride) and negatively-charged MONS and MWCNT. Ultraviolet–visible spectroscopy is used to probe the dynamic growth of multilayer film, exhibiting progressive enhancement of optical absorption due to the assembly of MONS and MWCNT. Thus, the assembled sandwiched film was characterized using scanning electron microscopy and X-ray photoelectron spectra. The multilayer film electrode presents excellent electrochemical capacitance properties, which were also highly dependent upon the deposition sequence and the order of structural components in sandwiched film.
[Show abstract][Hide abstract] ABSTRACT: Carbon nanotubes (CNTs)/mesostructured silica core-shell nanowires with a carbon nanotube core and controllable highly ordered
periodic mesoporous silica shell are syntheiszed via the interfacial surfactant template. The core-shell nanowires are characterized
by transmission electron microscope (TEM), X-ray diffraction pattern (XRD) and nitrogen sorption/desorption. The results indicate
that the core-shell nanowires have highly ordered periodic mesoporous silica shell (space group p6mm), high BET surface area and narrow pore size distribution. Moreover, the morphology of core-shell nanowires can be controlled
by the pH value. The core-shell nanowires have promising applications in biosensors, nanoprobes and energy storage due to
their good dispersibility in polar solvents.
Chinese Science Bulletin 01/2009; 54(3):516-520. · 1.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report a one-step synthesis of magnetic helical mesostructured silica (MHMS) by self-assembly of an achiral surfactant, magnetic nanocrystals with stearic acid ligands and silicate. This core-shell structured material consists of an Fe(3)O(4) superparamagnetic nanocrystal core and a highly ordered periodic helical mesoporous silica shell. We propose that the formation of the helical structure is induced by the interaction between the surfactant and dissociated stearic acid ligands. The MHMS obtained possesses superparamagnetism, uniform mesostructure, narrow pore size distribution, high surface area, and large pore volume. Furthermore, the drug release process is demonstrated using aspirin as a drug model and MHMS as a drug carrier in a sodium phosphate buffer solution.
[Show abstract][Hide abstract] ABSTRACT: In this paper, we report a novel synthesis and selective bioseparation of the composite of Fe3O4 magnetic nanocrystals and highly ordered MCM-41 type periodic mesoporous silica nanospheres. Monodisperse superparamagnetic Fe3O4 nanocrystals were synthesized by thermal decomposition of iron stearate in diol in an autoclave at low temperature. The synthesized nanocrystals were encapsulated in mesoporous silica nanospheres through the packing and self-assembly of composite nanocrystal–surfactant micelles and surfactant/silica complex. Different from previous studies, the produced magnetic silica nanospheres (MSNs) possess not only uniform nanosize (90 ∼ 140 nm) but also a highly ordered mesostructure. More importantly, the pore size and the saturation magnetization values can be controlled by using different alkyltrimethylammonium bromide surfactants and changing the amount of Fe3O4 magnetic nanocrystals encapsulated, respectively. Binary adsorption and desorption of proteins cytochrome c (cyt c) and bovine serum albumin (BSA) demonstrate that MSNs are an effective and highly selective adsorbent for proteins with different molecular sizes. Small particle size, high surface area, narrow pore size distribution, and straight pores of MSNs are responsible for the high selective adsorption capacity and fast adsorption rates. High magnetization values and superparamagnetic property of MSNs provide a convenient means to remove nanoparticles from solution and make the re-dispersion in solution quick following the withdrawal of an external magnetic field.
[Show abstract][Hide abstract] ABSTRACT: Actinobacillus pleuropneumoniae is the etiologic agent of porcine contagious pleuropneumonia, a cause of considerable world wide economic losses in the swine industry. We sequenced the complete genome of A. pleuropneumoniae, JL03, an isolate of serotype 3 prevalent in China. Its genome is a single chromosome of 2,242,062 base pairs containing 2,097 predicted protein-coding sequences, six ribosomal rRNA operons, and 63 tRNA genes. Preliminary analysis of the genomic sequence and the functions of the encoded proteins not only confirmed the present physiological and pathological knowledge but also offered new insights into the metabolic and virulence characteristics of this important pathogen. We identified a full spectrum of genes related to its characteristic chemoheterotrophic catabolism of fermentation and respiration with an incomplete TCA system for anabolism. In addition to confirming the lack of ApxI toxin, identification of a nonsense mutation in apxIVA and a 5'-proximal truncation of the flp operon deleting both its promoter and the flp1flp2tadV genes have provided convincing scenarios for the low virulence property of JL03. Comparative genomic analysis using the available sequences of other serotypes, probable strain (serotype)-specific genomic islands related to capsular polysaccharides and lipopolysaccharide O-antigen biosyntheses were identified in JL03, which provides a foundation for future research into the mechanisms of serotypic diversity of A. pleuropneumoniae.
PLoS ONE 02/2008; 3(1):e1450. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Nickel nanoparticles are prepared successfully through reducing nickel chloride by hydrazine hydrate and are tested as supercapacitor electrode material for the first time. The as-prepared nickel nanoparticles are characterized intensively by a variety of means such as SEM, TEM, XRD and XPS. TEM observations and XRD analysis demonstrated that the size of nickel nanoparticles is about 12 nm. XPS analyses indicate that the surface nickel atoms can react easily with O2 and water in the atmosphere to form nickel oxide/hydroxide species. As evidenced by electrochemical measurements, these surface nickel oxide/hydroxide species can generate substantial pseudocapacitance, reaching up to 416.6 F g− 1 for nickel nanoparticles, which is higher than most carbon electrode materials reported in the literatures. This kind of surface metal oxides/hydroxides that generate pseudocapacitance may also occur on other metal nanoparticles except nickel nanoparticles, which provides a new approach to searching for electrode materials with even higher capacitance.