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Zhimin Liu

Publications and source records attributed to Zhimin Liu.

At least 19 recordsLinked to original sources
PubMed2006

The role of reproductive phenology, seedling emergence and establishment of perennial Salix gordejevii in active sand dune fields.

BACKGROUND AND AIMS: The function of sexual reproduction of perennials in restoration of vegetation of active dune fields frequently has been underestimated. The objective of this study was to evaluate the role of sexual reproduction of the perennial Salix gordejevii in the revegetation of active dunes. METHODS: Seedling emergence and establishment of S. gordejevii were examined both in controlled experiments (germination at different burial depths with different watering regimes) and in field observations in three dune slacks. The reproductive phenology and soil seed bank of S. gordejevii, the dynamics of soil moisture, the groundwater table and the landform level of three dune slacks were monitored. KEY RESULTS: Seeds of S. gordejevii began maturation on 1 May, and seed dispersal lasted from 8 May to 20 May. Seeds on the soil surface germinated significantly faster than those buried in soil (P<0.05). Seedling emergence was negatively correlated with landform level. When most seedlings emerged, there was a significantly positive correlation between soil moisture and seedling emergence (P<0.01). Rainfall was negatively correlated with seedling emergence. Seedling establishment was significantly and positively correlated with seedling emergence (P<0.05), and 72.3 % of the emergent seedlings were established at the end of the growing season. These results indicated that (a) seeds matured and dispersed before the rainy season; (b) seeds germinated as soon as they contacted a moist surface and relied more on soil moisture than on rainfall; and (c) more seedlings emerged at lower sampling points in dune slacks. CONCLUSIONS: In natural conditions, restoration of active sand dune fields generally commences with revegetation of dune slacks where sexual reproduction of perennials contributes greatly to species encroachment and colonization and hence plays an important role in restoration of active dune fields. Furthermore, aeolian erosion in dune slacks, leading to good soil moisture, facilitates seed germination, seedling emergence and establishment of S. gordejevii.

Ecosystem↗
PubMed2006

Decoration carbon nanotubes with Pd and Ru nanocrystals via an inorganic reaction route in supercritical carbon dioxide-methanol solution.

This work describes a method to decorate carbon nanotubes (CNTs) with metallic Pd and Ru nanocrystals via inorganic reactions in supercritical (SC) CO2-methanol solutions. In this route, PdCl2 or RuCl3.3H2O dissolved in SC CO2-methanol solution acted as a metal precursor and CNTs functioned as a template to direct the deposition of produced nanoparticles. Methanol served as the reductant for the precursors as well as cosolvent to enhance the dissolution of precursors in SC CO2. Dry products were readily obtained through in situ extraction with SC CO2 after reactions. The products were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. It was demonstrated that the loading content and particle size of the nanoparticles deposited on CNTs could be tuned by changing the weight ratio of the precursor to CNTs. This simple and efficient approach may also be utilized to synthesize other high-purity materials using inorganic salt precursors in SC CO2-based solution.

Journal Article↗
PubMed2006

Synthesis of ZrO2-carbon nanotube composites and their application as chemiluminescent sensor material for ethanol.

ZrO2-carbon nanotube (CNT) composites have been successfully synthesized via decomposition of Zr(NO3)4.5H2O in supercritical carbon dioxide-ethanol solution with dispersed CNTs at relatively low temperatures. The samples were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), and energy-dispersive X-ray (EDX) analyses. It was demonstrated that CNTs were fully coated with an amorphous ZrO2 layer, and the coating layer was nominally complete and uniform. In addition, the thickness of the coating sheath could be readily controlled by tuning the Zr(NO3)4.5H2O/CNTs ratio used. Furthermore, the chemiluminescent sensor prepared from ZrO2-carbon nanotube composites exhibited dramatic sensitivity as well as high stability and selectivity to ethanol.

Journal Article↗
PubMed2006

Synthesis and characterization of ZnS-montmorillonite nanocomposites and their application for degrading eosin B.

Nanocomposites of zinc sulfide (ZnS) and montmorillonite (MMT) were prepared via a hydrothermal route. In this method, the MMT treated with hexadecyltrimethyl ammonium bromide (HTAB) aqueous solution was dispersed in the aqueous solution of thiourea and Zn(OOCHCH(3))(2)2H(2)O, and heated at 170 degrees C for about 4 h, resulting in ZnS-MMT composites. The as-prepared nanocomposites were characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen sorption analysis. It was demonstrated that the interlayer space of MMT was enlarged from 0.98 to 3.77 nm after the treatment with HTAB aqueous solution, and the ZnS nanoparticles were deposited on the layers of MMT. Nitrogen sorption analysis demonstrated that the specific surface area of the samples decreased from 39.2 m(2)/g of the pristine MMT to 5.9 m(2)/g of the final ZnS-MMT composites. The resulting ZnS-MMT nanocomposites (50.0 mg) could degrade eosin B completely in aqueous solution (75 ml, 3.2x10(-5) M) within 20 min under UV irradiation.

Journal Article↗
PubMed2006

Micropatterned polymer surfaces induced by nonsolvent.

In this work, we present a facile method for fabricating polymer thin films with micropatterned surfaces by evaporating polymer solution containing a small amount of nonsolvent of polymer in air. Poly(methyl methacrylate) (PMMA) and polystyrene (PS) films with densely packed micropores on the surfaces were fabricated. This method was also used to prepare three-dimensional PMMA films with micropatterned surfaces. The effects of nonsolvent content; evaporation temperature; and interactions between the polymer, solvent, and nonsolvent on the specific patterns were investigated, and the formation mechanism of the pores is discussed. This simple route can potentially be used, for example, in the large-scale production of patterned surfaces, three-dimensional painting, and hydrophobicity-enhancing coatings.

Journal Article↗
PubMed2006

Diagnostic associations between pleural and pulmonary tuberculosis.

OBJECTIVE: To evaluate diagnostic differences and associations between pleural tuberculosis (PLTB), and pulmonary tuberculosis alone (PTB), as well as, pleural and pulmonary co-infection (PLPTB) and PTB. METHODS: Data from a 6-year, population-based study in Houston, Texas, were analyzed by logistic regression modeling. Study personnel interviewed 2226 tuberculosis cases for TB risk assessment and reviewed medical records. Mycobacterium tuberculosis isolates from available culture-positive patients underwent genotyping. RESULTS: Among the categories analyzed [PTB, n=2070; PLTB, n=95; and PLPTB, n=61], mortality within 180 days of TB presentation was highest for PLPTB patients (HR=1.8, P=0.045), followed by PTB (HR=1.0, referent), and PLTB (HR=0.97, P=0.9), after adjustment for age and HIV. Multivariate analysis identified history of liver disease, MTB culture negativity, having symptoms for <60 days, chest pain, and age>64 years as independent risk factors for PLTB. Symptoms for <60 days and HIV seropositivity predicted PLPTB. Patients with PLTB were significantly less likely to be genotypically clustered than patients presenting with PTB and patients diagnosed with PLPTB were significantly more likely to be identified has part of a cluster than pulmonary TB patients. CONCLUSIONS: PLTB presented as a more acute infection with additional symptoms and fewer symptomatic days, while PLPTB presented as a more severe disease with higher mortality compared with PTB. Given the different manifestations seen in this study, the biological mechanisms by which the pleural space is involved for PLTB and PLPTB may be substantially different.

Adult↗
PubMed2006

Controlled synthesis of Ag/TiO2 core-shell nanowires with smooth and bristled surfaces via a one-step solution route.

Ag/TiO2 core-shell nanowires were synthesized via a one-step solution method without using a template. Interestingly, the shell morphologies can be controlled to be smooth or bristled by altering the reaction temperature. Moreover, the TiO2 shell thickness and bristle length can be tuned by changing the AgNO3 concentration. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), energy-dispersive X-ray analysis (EDS), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize the resultant Ag/TiO2 core-shell nanowires. Moreover, the absorption peaks of our samples are significantly red-shifted compared with those of the uncoated pure silver nanowires, indicating that interaction between the core and shell occurred. On the basis of the experimental results, we proposed a template-induced Oswald ripening mechanism to explain the formation of the Ag/TiO2 core-shell nanowires.

Journal Article↗
PubMed2006

Drug use and HIV/AIDS in China.

This paper on drug use and HIV/AIDS in China follows on from the column's May 2005 article on the description of the first methadone maintenance clinic in Beijing. Methadone maintenance clinics and needle exchange programmes are now being implemented in China as a response to the rapid increase in prevalence of HIV/AIDS over the last 10-15 years. It is worth noting that in prior years methadone was available only as for short-term detoxification from opioids and for research purposes. Accordingly, the Department of Health Education and Behavioural Intervention at the National Center for AIDS Prevention and Control in China plans to establish 1,000 methadone replacement clinics within the next 5 years to treat 200,000 heroin-dependent users who are at increased risk of HIV/AIDS. Robert Ali & Rachel HumeniukEditors, Asia Pacific ColumnThe cumulative number of registered drug users in mainland China increased from 70,000 in 1990 to 1.14 million in 2004. Heroin continues to be the most commonly used drug in China; however, polydrug use is popular among heroin users. Sedatives/hypnotics (e.g. triazolam) and other uncontrolled prescription opioids (e.g. pethidine and tramadol) are used commonly in combination with heroin. The majority of drug users (79%) are young people aged between 17 and 35 years and comprise predominantly farmers (30%) and unemployed people (45%). The HIV/AIDS epidemic in China has reached expansion phase (1995-present). It is estimated that the actual number of HIV/AIDS cases reached 840,000, including 80,000 actual AIDS patients, in 2003, with injecting drug users (IDUs) making up the largest proportion of these cases. Although the prevalence rate of HIV/AIDS is only 0.065% in the Chinese population overall, there is potential for an explosive spread of HIV/AIDS if preventative measures are not employed. Supported by the Chinese government and other related international organisations, harm reduction strategies such as methadone maintenance treatment (MMT) and needle-syringe programmes (NSP) have commenced implementation to reduce the risk of HIV infection among heroin users.

Acquired Immunodeficiency Syndrome↗
PubMed2006

rpoB Gene mutations and molecular characterization of rifampin-resistant Mycobacterium tuberculosis isolates from Shandong Province, China.

Sixty rifampin (RIF)-resistant and 75 RIF-susceptible Mycobacterium tuberculosis isolates from Shandong Province, China, were analyzed for rpoB gene mutations and genotyped. Mycobacterial interspersed repetitive unit (MIRU) genotype 223325173533 was overrepresented among RIF-resistant isolates. MIRU combined with IS6110 restriction fragment length polymorphism analysis as the second-line genotyping method may reflect epidemiologic links more reliably than each method alone.

Antibiotics, Antitubercular↗
PubMed2006

Synthesis of noble metal/carbon nanotube composites in supercritical methanol.

A simple and efficient route has been employed to deposit noble metal nanoparticles (Pt, Ru, Pt-Ru, Rh, Ru-Sn) onto carbon nanotubes (CNTs) in supercritical methanol solution. In this method, the inorganic metallic salts acted as metal precursors, and methanol as solvent as well as reductant for the precursors. The as-prepared nanocomposites were structurally and morphologically characterized by X-ray diffraction spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy, and X-ray photoelectron spectroscopy analyses. It was demonstrated that the CNTs were decorated by crystalline metal nanoparticles with uniform sizes and a narrow particle size distribution. The size and loading content of the nanoparticles on CNTs could be tuned by manipulating reaction parameters. Furthermore, the formation mechanism of the composites was also discussed.

Chromatography, Supercritical Fluid↗
PubMed2006

Microwave-assisted synthesis of pt nanocrystals and deposition on carbon nanotubes in ionic liquids.

In this work, a simple, fast and efficient route is presented for the metal (such as Pt, Rh, etc.) nanocrystal synthesis and deposition on carbon nanotubes (CNTs) in ionic liquids (ILs) via microwave heating. In this method, inorganic salts (such as H2PtCl6.4H2O, RhCl3.2H2O, etc.) dissolved in ILs, 1,1,3,3-tetramethylguanidinium trifluoroacetate or 1,1,3,3-tetramethylguanidinium lactate, were reduced to metal nanoparticles by glycol with the aid of microwave heating, and the produced metal nanoparticles could be decorated on CNTs in the presence of CNTs in ILs. The resulting nanomaterials were characterized by means of transmission electron microscopy and X-ray diffraction. It was demonstrated that the homogeneously dispersed Pt nanocrystals with the size of 2-3 nm were obtained using H2PtCl6.4H2O as precursor, and they deposited on CNTs with the similar size when CNTs was present in ILs. This technique also can be extended to fabricate other noble metal nanocrystals (including Rh, Au, etc.) and corresponding CNT composites.

Carbon↗
PubMed2006

Synthesis of polyaniline nanofibrous networks with the aid of an amphiphilic ionic liquid.

In this work, polyaniline (PANI) nanofibrous networks were prepared using ionic liquid (IL), 1-hexadecyl-3-methylimidazolium chloride (C16MIMCl), as a template through oxidative polymerization of aniline with ammonium persulfate. The resulting PANI was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis, and FTIR. It was indicated that the as-prepared PANI was in the emeraldine form and its morphology strongly depended on the molar ratio of aniline/C16MIMCI. A possible mechanism for the formation of PANI nanofibrous networks was that the ordered micro-domains of the IL acted as template to direct the growth of the nanostructures.

Aniline Compounds↗
PubMed2006

[Germination strategy and ecological adaptability of Eragrostis pilosa].

The study on the germination strategy of Eragrostis pilosa under different storage and environmental conditions showed that freshly collected E. pilosa seeds had a stronger innate dormancy. Chilling and dry storage for 4 months had no obvious effect on releasing from dormancy, while longer time storage could facilitate seed maturation. The seeds could germinate either in light or in darkness, and stronger light was in favor of germination. The optimal temperature for germination was 28 degrees C, while higher or lower temperature could result in the decrease of germination. The germination percentage of seeds under changed temperature (16 to 28 degrees C) was higher than that under constant temperature (28 degrees C), but with no significant difference. The critical amount of rain for seed germination was about 10 mm, and the germination percentage and duration all increased with increasing rainfall. E. pilosa had two germination strategies, i. e., quick germination and dormancy for more than one year. Based on the seed morphological characters and germination strategies, it could be concluded that E. pilosa had a persistent soil seed bank.

Adaptation, Physiological↗
PubMed2005

Carbon microspheres with supported silver nanoparticles prepared from pollen grains.

In this paper, we present a new method to fabricate carbon microspheres with supported silver nanoparticles on the surfaces. In this method, pollen grains were first treated with AgNO(3) aqueous solution, then preoxidized in air at 300 degrees C and carbonized in nitrogen at 600 degrees C, resulting in the silver/carbon nanocomposites. The silver/carbon nanocomposites were characterized by means of SEM, TEM, TG, and XRD. The size and distribution of the silver nanoparticles on the carbon microsphere surface could be controlled by tuning the AgNO(3) treatment conditions.

Journal Article↗
PubMed2005

Phase separation of the reaction system induced by CO2 and conversion enhancement for the esterification of acetic acid with ethanol in ionic liquid.

The effect of CO2 on the phase behavior of the reaction system and equilibrium conversion for esterification of acetic acid and ethanol in ionic liquid (1-butyl-3-methylimidazolium hydrogen sulfate, [bmim][HSO4]) was studied at 60.0 degrees C up to 15 MPa. It was demonstrated that there was only one phase in the reaction system in the absence of CO2. The reaction system underwent two-phase-->three-phase-->two-phase transitions with increasing pressure. The pressure of CO2 or the phase behavior of the system affected the equilibrium conversion of the reaction markedly. As the pressure was less than 3.5 MPa, there were two phases in the system, and the equilibrium conversion increased as pressure was increased. In the pressure range of 3.5-9.5 MPa, there existed three phases, and the equilibrium conversion increased more rapidly with increasing pressure. As the pressure was higher than 9.5 MPa, the reaction system entered another two-phase region and the equilibrium conversion was nearly independent of pressure. The total equilibrium conversion was 64% without CO2 and could be as high as 80% as pressure was higher than 9.0 MPa. The apparent equilibrium constants (K(x)) in different phases were also determined, showing that the K(x) in the middle phase or top phase was much greater than that in the bottom phase.

Journal Article↗
PubMed2005

Synthesis of single-crystal gold nanosheets of large size in ionic liquids.

Large-size single-crystal gold nanosheets have been successfully prepared by microwave heating of HAuCl(4) in ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, without any additional template agent. Transmission electron microscopy (TEM), electron diffraction (ED), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) were used to characterize the resultant gold nanosheets. It was demonstrated that the ionic liquid could act as template agent for the formation of gold nanosheets. The present synthesis route is very simple and fast. It can be expected that the method can be extended to the fabrication of other metal nanosheets in ionic liquids.

Journal Article↗