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1.
The influence of calcination temperature on TiO2 nanotubes＇ catalysis for TiO2/UV/03 was investigated. TiO2 nanotubes （TNTs） were prepared via the sol-gel method and calcined at 300--700 ℃, which were labeled as TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700, respectively. TNTs were characterized by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. It is found that TNTs calcined at 400 ℃ showed the best thermal stability. When the calcination temperature increased from 400 ℃ to 700 ℃, the special structure of tubes was destroyed and gradually converted into nanorods and/or particles. The transformation from anatase to rutile occurred at 600 ℃, and the rutile phase was enhanced when the calcination temperature was increased to over 600 ℃. The calcina- tion temperature＇s influence on TNTs＇ adsorption activity for for TiO2/UV/O3 was investigated in landfill leachate solution chemical oxygen demand （COD） and catalytic activity In landfill leachate solution, the adsorption activity of COD decreased in the reduced order of TNTs-300, TNTs-400, TNTs-500, TNTs-600 and TNTs-700. In photocatalytic ozonation, TNTs-400 showed the best catalytic activity while TNTs-700 exhibited the worst. In other three processes, the COD removal of TNTs-300/UV/O3 was higher than those of TNTs-500/UV/O3 and TNTs-600/UV/O3 in the first 20 rain, and then became close to those of the latter two in the following 40 rain. Compared with TNTs-300 and TNTs- 400, TNTs-600 had the best anti-fouling activity, while TNTs-500 and TNTs-700 had lower anti-fouling activity than the former three. In photocatalytic ozonation, the calcination temperature of 400 ℃ was appropriate when TNTs were obtained at the synthesis temperature of 105 ℃.  相似文献   

2.
Characteristics of fluoride emission from five clay minerals (montmorillonite, kaolinite, vermiculite, geothite, and allophane) as affected by temperature, heating time and addition of calcium compounds were studied. Marked increase of the fluoride emission rate was noticed with increase of temperature. The fluoride release, began at 500°C–600°C, and the main bulk of the fluoride emission occurred at the temperature of about 800°C. The loss of crystalline water was primarily responsible for the increase of fluoride emission. When minerals were heated at 800°C, The fluoride emission rate from the clay minerals reached the highest after heating for 1 hour. The samples treated by CaO, CaCO3, Ca(OH)2, Ca3(PO4)2, and CaSO4 had 55.45%, 59.58%, 46.45%, 54.31%, 31.25% reduction in the fluoride emission from montmorillonite at the temperature of 800°C, respectively. CaCO3 had the highest fluoride fixing capacity compared to other calcium compounds. Project supported by the Special Funds for Major State Basic Research Project 973 (G1999011809) and Natural Science Foundation of Zhejiang Province.  相似文献   

3.
Ａｌｕｍｉｎｕｍ ＡｌｌｏｙｓTX１ＩｎｔｒｏｄｕｃｔｉｏｎＦｅ－Ａｌｉｎｔｅｒｍｅｔａｌｉｃｓｈａｖｅｇｒｅａｔｐｏｔｅｎｔｉａｌｉｔｉｅｓｆｏｒｓｔｒｕｃｔｕｒａｌａｐｐｌｉｃａｔｉｏｎｓｏｗｉｎｇｔｏｔｈｅｉｒｇｏｏｄｍｅｃｈａｎｉｃａｌｐｒｏｐ...  相似文献   

4.
Nanometer-sized SnO2 particles were prepared by a sol-gel method using inorganic salt as a precursor material. Its crystallization was investigated by means of TG-DTA, IR absorption spectra, X-ray diffractometry and TEM as well as its resistivity change and the gas sensitivity varied with temperature were measured in various reducing gas. The results indicate that well-crystallized nano-sized SnO2 with size around 15nm can be obtained at annealing temperature 600°C. The activation energy for the growth of nano-SnO2 was calculated to be 26. 55kJ. mol−1 when the annealing temperature was higher than 500°C. The measurements also show that there is a peculiar resistance change varied with temperature for nano-SnO2. It has relevance to the increase in surface adsorbed oxygen. The selective detectivities to C4H10 and petrol can be increased when ruthenium ion was doped in nano-SnO2 as a catalyst and so do the gas sensitivity to CO, CH4, H2 etc. when rhodium ion was doped in. The detection to the several reducing gas can be realized when the temperature ranged from 260°C to 400°C.  相似文献   

5.
With InCl3·4H2O being used as raw materials, the precursor of nano-sized In2O3 powder was prepared by hydrolysis, peptization and gelation of InCl3·4H2O. After calcination, nano-sized In2O3 powder was obtained. The powder was characterized by thermo-gravimetric and differential thermal analysis (TG-DTA), X-ray diffractometry (XRD) and transmission electron microscopy (TEM), respectively. Calculation revealed that the mean crystalline size increased with increasing the calcination temperature, but crystal lattice distortion rate decreased with the increasing in the average crystalline size. This indicated that the smaller the particle size, the bigger the crystal lattice distortion, the worse the crystal growing. The activation energies for growth of nano-sized In2O3 were calculated to be 4.75 kJ·mol−1 at the calcination temperature up to 500°C; and 66.40 kJ·mol−1 at the calcination temperature over 600°C. TEM photos revealed that the addition of the chemical additive (OP-10) greatly influenced the morphology and size of In2O3 particles.  相似文献   

6.
In this study, we used a simple impregnation method to prepare Fe–Ce–O x catalysts and tested them regarding their low-temperature (200–300 °C) selective catalytic reduction (SCR) of NO using NH3. We investigated the effects of Fe/Ce molar ratio, the gas hourly space velocity (GHSV), the stability and SO2/H2O resistance of the catalysts. The results showed that the FeCe(1:6)O x (Ce/Fe molar ratio is 1:6) catalyst, which has some ordered parallel channels, exhibited good SCR performance. The FeCe(1:6)O x catalyst had the highest NO conversion with an activity of 94–99% at temperatures between 200 and 300 °C at a space velocity of 28,800 h?1. The NO conversion for the FeCe(1:6)O x catalyst also reached 80–98% between 200 and 300 °C at a space velocity of 204,000 h?1. In addition, the FeCe(1:6)O x catalyst demonstrated good stability in a 10-h SCR reaction at 200–300 °C. Even in the presence of SO2 and H2O, the FeCe(1:6)O x catalyst exhibited good SCR performance.  相似文献   

7.
Fluidized-bed pyrolysis of waste bamboo   总被引：1，自引：0，他引：1  
Bamboo was a popular material substituting for wood,especially for one-off commodity in China. In order to recover energy and materials from waste bamboo,the basic characteristics of bamboo pyrolysis were studied by a thermogravimetric analyzer. It implied that the reaction began at 190～210 °C,and the percentage of solid product deceased from about 25% to 17% when temperature ranged from 400 °C to 700 °C. A lab-scale fluidized-bed furnace was setup to research the detailed properties of gaseous,liquid and solid products respectively. When temperature increased from 400 °C to 700 °C,the mass percent of solid product decreased from 27% to 17% approximately,while that of syngas rose up from 19% to 35%. When temperature was about 500°C,the percentage of tar reached the top,about 31%. The mass balance of these experiments was about 93%～95%. It indicated that three reactions involved in the process: pyrolysis of exterior bamboo,pyrolysis of interior bamboo and secondary pyrolysis of heavy tar.  相似文献   

8.
The cyclic oxidation behaviors of Fe-28Al-5Cr-O. 1Zr (at%) and Fe-28A15Cr-O. 5Nb (at%) alloys have been investigated in air at high temperature. The results show that the distinctive whisker-like oxides were formed on the surface of Zr-containing Fe3 Al based alloy after 500 hrs. cyclic oxidation at 800 °C and 1000 °C. The results also indicate that the addition of small amount of Zr to Fe3 Al based alloy can improve its adherence strength between the oxides and metal substrate and is beneficial to the oxidation resistance. However, for the Nb-containing Fe3 Al based alloy, porous convoluted oxides were formed after 350 hrs. cyclic oxidation at 1000°C, and this type of oxides didn’t not contribute to the oxidation resistance.  相似文献   

9.
以木屑为原料,高温热解制备生物炭。以聚乙烯醇为粘结剂,采用混合法将生物炭与果胶复合,并负载磁性,经烘干定型制备果胶包覆的磁性生物炭材料（果胶@生物炭-Fe3O4）。采用扫描电镜（SEM）、X射线衍射（XRD）及N2吸附-脱附（BET）等方法对果胶@生物炭-Fe3O4进行表征,结合吸附实验分析其对Cu2+的吸附特性。结果表明,当生物炭、果胶、Fe3O4质量比为5：1：1,溶液pH值为6,吸附24 h,果胶@生物炭-Fe3O4对Cu2+吸附效果最好;二级动力学方程能较好地描述果胶@生物炭-Fe3O4对Cu2+的吸附过程,Freundlich模型能较好地拟合其吸附行为;SEM结果显示该材料具有不规则的孔隙结构;XRD分析显示纳米Fe3O4是其主要的晶体结构;BET测得其比表面积为25.654 m2·g-1,平均孔径为20.18 nm。  相似文献   

10.
Enantiomers (R(+) and S(-)),RS-racemate (double compound) and (R+S)-conglomerate (mechanical mixture of enantiomers) of malic acid C 4 H 6 O 5 have been investigated by means of X-ray diffractometry and high temperature X-ray diffraction method.The RS-racemate was found to be able to form three polymorphic modifications,which we denominated as M1 (monoclinic,space group P2 1 /c),M2 (monoclinic,space group Cc),and Tc (triclinic,space group P-1),the latter modification having been unknown before.Modification Tc was also described,and its Xray diffraction characteristics,including interplanar spacings d,hkl indices,unit cell parameters,were defined.In addition,X-ray diffraction characteristics for both reported earlier M1 and M2 monoclinic polymorphic modifications were measured with higher accuracy.The ability of RS-racemate to form one of the above three modifications (M1,M2,and Tc) or their mixtures containing various proportions and combinations of the components (M1+M2,M1+Tc,or M2 +Tc) was found to depend on the type of crystallization medium (a melt,aqueous medium,ethanol or acetone solution),crystallization rate (from 2-3 minutes to 4 months),and crystallization temperature.Heating S-enantiomer and M1 RS-racemate up to their respective melting points (100 ℃ and 124 ℃,correspondingly) only made them undergo thermal deformations,while heating (R+S)-conglomerate in the temperature range of 96-110 ℃ resulted in its homogenization to form M2 RS-racemate,which,near the melting point (118 ℃),namely,in the range of 112-116 ℃,was transformed into M1 RS-racemate.  相似文献   

11.
Cu(In,Ga)Se2 (CIGS) precursor films were deposited on Mo/glass by electrodeposition, and then annealed in Se vapor. The annealing temperature ranged from 450 °C to 580 °C, and two heating rates were selected. The results showed that the crystalline quality of the CIGS films and formation of the Cu-Se compound could be strongly influenced by the selenization temperature and heating rate. Raman spectroscopy and X-ray diffraction (XRD) analysis showed that when the selenization temperature was increased from 450 °C to 550 °C, the amount of binary CuSe phase decreased and the amount of Cu2Se increased. After annealing at 580 °C, a minimum amount of Cu2?xSe compounds was obtained and the degree of CIGS film crystallinity was higher than in other samples. The relationship between the properties of the film and the heating rate was studied. XRD and Raman spectra showed a decrease in the Cu2?xSe phase with increasing heating rate. Scanning electron microscopy (SEM) and XRD showed a remarkable increase in the grain size of CIGS during rapid heating.  相似文献   

12.
An experimental and model-based study of the effect of rich air/fuel ratios （AFRs） and temperature on the NOx slip of a lean NOx trap （LNT） was conducted in a lean-burn gasoline engine with an LNT after-treatment system. The emissions of the engine test bench and the inlet temperature of the LNT were used as the major inlet boundary conditions of the LNT. The engine periodically operated between a constant lean AFR of 23 with alterable rich AFRs of 10, 11, 12, 13, and 14. A decrease in the rich AFR of the engine strengthened the desorption atmosphere in the LNT, an effect closely related to the number of reductants, and further heightened the NOx desorption of the LNT, but with a penalty in fuel consumption. To eliminate that penalty, the inlet boundary conditions of the LNT were varied by adjusting the inlet temperature within a range between 200 ℃ and 400℃. An increase in inlet temperature heightened the NOx desorption of the LNT, and a NOx breakthrough occurred after the inlet tem- perature exceeded 390 ℃. To control NOx breakthrough, the inlet temperature can be adjusted to offset the strong desorption atmosphere in the LNT commonly created by a rich AFR.  相似文献   

13.
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14.
The simultaneous sorption behavior and characteristics of cadmium (Cd) and sulfamethoxazole (SMX) on rice straw biochar were investigated. Isotherms of Cd and SMX were well modeled by the Langmuir equation (R2 >0.95). The calculated maximum adsorption parameter (Q) of Cd was similar in single and binary systems (34129.69 and 35919.54 mg/kg, respectively). However, the Q of SMX in a binary system (9182.74 mg/kg) was much higher than that in a single system (1827.82 mg/kg). The presence of Cd significantly promoted the sorption of SMX on rice straw biochar. When the pH ranged from 3 to 7.5, the sorption of Cd had the characteristics of a parabola pattern with maximum adsorption at pH 5, while the adsorption quantity of SMX decreased with increasing pH, with maximum adsorption at pH 3. The amount of SMX adsorbed on biochar was positively correlated with the surface area of the biochar, and the maximum adsorption occurred with d 250 biochar (biochar with a diameter of 150-250 μm). Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) showed that the removal of Cd and SMX by rice straw biochar may be attributed to precipitation and the formation of surface complexes between Cd or SMX and carboxyl or hydroxyl groups. The results of this study indicate that rice straw biochar has the potential for simultaneous removal of Cd and SMX from co-contaminated water.  相似文献   

15.

Objective

Many investigations have studied the associations between matrix metalloproteinase-9 (MMP-9) C1562T polymorphisms and coronary artery disease (CAD). However, the conclusions of these studies were inconsistent. Therefore, this study was aimed at clarifying the association between MMP-9 C1562T polymorphisms and CAD in a large-scale meta-analysis.

Methods

The PubMed and Embase databases were retrieved to collect all publications on the association between MMP-9 C1562T polymorphisms and CAD. Then the odd ratios (ORs) and 95% confidence intervals (95% CIs) for C1562T TT+TC versus CC genotype between CAD and the control groups were evaluated. Subgroup analysis was also performed according to different races. The meta-analysis was performed by Stata 10.0.

Results

Sixteen case-control studies were included in our meta-analysis, involving 11 032 CAD patients and 4628 non-CAD controls. Compared with C allele carriers, East Asian T allele carriers TT+TC had a significantly higher risk of CAD (OR=1.43; 95% CI: 1.03–1.99; P=0.031); however, there were no significant associations in Western populations (OR=1.06; 95% CI: 0.96–1.18; P=0.240) or West Asians (OR=1.13; 95% CI: 0.75–1.70; P=0.565). When further analyzing the association between C1562T polymorphisms and myocardial infarction (MI, the most serious type of CAD), the risk of TT+TC genotype versus CC genotype for MI was significantly higher for the overall (OR=1.21; 95% CI: 1.04–1.40; P=0.012) and for East Asians (OR=1.58; 95% CI: 1.26–1.97; P=0.000) but not in Western populations (OR=1.12; 95% CI: 0.99–1.26; P=0.078).

Conclusions

Our meta-analysis suggested an obvious ethnic difference in the association between MMP-9 C1562T polymorphisms and CAD. MMP-9 C1562T polymorphism was significantly related to CAD in East Asians. However, no significant associations were observed in either West Asians or Western populations.  相似文献   

16.
A rice pse(t) (premature senescence, tentatively) mutant line, was isolated from 4500 independent T-DNA inserted transgenic lines. The symptoms of premature senescence appeared more severely than those of the control plants (Zhonghua 11,japonica) at the last development stage. To characterize the mutant and provide basic information on the candidate genes by mapping to a physical region of 220-kb, experiments were carried out in two phytotrons under controlled temperature of 24 ℃ and28 ℃, respectively. The content of chlorophyll, soluble protein and MDA (malondialdehyde), net photosynthesis, the antioxidant enzyme activities of SOD (superoxide dismuase) (EC 1.15.1.1) and POD (peroxidase) (EC 1.11.1.7) and the peptidase activities of leaves were measured from top to bottom according to the leaf positions at the flowering stage. Compared with the control plant,the mutant showed the following characteristics: (1) Higher net photosynthesis rate (Pn) appeared in the 1 st and 2nd leaves, contents of chlorophyll and soluble protein were also higher in the 1 st leaf; (2) The activities of SOD, POD and peptidase were higher according to the leaf position from top to bottom; (3) The symptom of premature senescence was accelerated in the mutant at 28℃treatment. The MDA content and the SOD and POD activities between the 24 ℃ and 28 ℃ treatment mutants were not significantly different. Content of chlorophyll and soluble protein of leaves mutant decreased rapidly at 28 ℃ treatment. The results show that pse(t) is sensitive to high temperature. The probable function of PSE(T) is discussed.  相似文献   

17.
The production of elastase by Bacillus sp. EL31410 at various temperatures was investigated. In order to study the effect of temperature on elastase fermentation, different cultivation temperatures, ranging from 39 °C to 28 °C, were evaluated in shake flask. The result indicated that 37 °C was best for cell growth at earlier stage; while maximum elastase activity was obtained when the cells were cultivated at 30 °C. This result was verified by batch fermentation in 5-L bioreactor under 37 °C and 30 °C temperature, respectively. The specific cell growth rate at 37 °C was higher than that at 30 °C during earlier stage of cultivation. The maximum value [5.5 U/(h·g DCW)] of elastase formation rate occurred at 24 h at 30 °C compared to 4.6 U/(h·g DCW) at 30 h at 37 °C. Based on these results, two-stage temperature shift strategy and oscillatory temperature cultivation mode were evaluated in the next study. When compared to single temperature of 37 °C or 30 °C, both two-stage temperature shift strategy and oscillatory temperature strategy improved biomass but did not yield the same result as expected for elastase production. The maximum biomass (both 8.6 g/L) was achieved at 30 h at 37 °C, but at 42 h using two-stage temperature cultivation strategy. The highest elastase production (652 U/ml) was observed at 30 °C in batch process. It was concluded that cultivation at constant temperature of 30 °C was appropriate for elastase production by Bacillus sp. EL31410. Project (No. 20276064) supported by the National Natural Science Foundation of China  相似文献   

18.
An ultrasonic-assisted technique was employed to extract crude polysaccharide from Tricholoma matsutake fruiting bodies. Single-factor tests and orthogonal experimental design (L 9(33)) were used to obtain the optimal extraction conditions. Results showed that the optimal parameters were as follows: ultrasonic temperature, 40 °C; ultrasonic time, 50 min; water to raw material ratio, 25 ml/g; ultrasonic frequency, 45 kHz; and ultrasonic power, 100 W. Three novel T. matsutake polysaccharide (TMP) fractions (TMP30, TMP60, and TMP80) were isolated and purified from TMP by stepwise alcohol precipitation. Their preliminary structural features were determined by high-performance anion-exchange chromatography with pulsed-amperometric detection (HPAEC-PAD) and Fourier transform infrared spectrophotometer (FT-IR) analyses. Furthermore, their in vitro antioxidant activity was investigated in terms of a reducing power assay and the scavenging rates of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radicals. The order of the various fractions based on their antioxidant activity was TMP80>TMP>TMP60>TMP30. These findings suggested that novel polysaccharide fractions from T. matsutake, especially TMP80, could be promising active macromolecules for biomedical use.  相似文献   

19.
This study was conducted to investigate the combined effects of elevated CO2 levels and cadmium (Cd) on the root morphological traits and Cd accumulation in Lolium multiflorum Lam. and Lolium perenne L. exposed to two CO2 levels (360 and 1 000 μl/L) and three Cd levels (0, 4, and 16 mg/L) under hydroponic conditions. The results show that elevated levels of CO2 increased shoot biomass more, compared to root biomass, but decreased Cd concentrations in all plant tissues. Cd exposure caused toxicity to both Lolium species, as shown by the restrictions of the root morphological parameters including root length, surface area, volume, and tip numbers. These parameters were significantly higher under elevated levels of CO2 than under ambient CO2, especially for the number of fine roots. The increases in magnitudes of those parameters triggered by elevated levels of CO2 under Cd stress were more than those under non-Cd stress, suggesting an ameliorated Cd stress under elevated levels of CO2. The total Cd uptake per pot, calculated on the basis of biomass, was significantly greater under elevated levels of CO2 than under ambient CO2. Ameliorated Cd toxicity, decreased Cd concentration, and altered root morphological traits in both Lolium species under elevated levels of CO2 may have implications in food safety and phytoremediation.  相似文献   

20.
A laboratory incubation experiment was conducted to study the effect of copper as cupric sulfate (CuSO4.5H2O), and lead as lead acetate (Pb (OAc)2) on the size of the microbial biomass in red soil. The metals were applied, separately at six different levels: Cu at 50, 100, 200, 300, 400, and 600 μg·g−1 soil and Pb at 100, 200, 400, 600, 800, and 1000 μg·g−1 soil. In comparison to uncontaminated soil, the microbial biomass carbon (Cmic) and biomass nitrogen (Nmic) decreased sharply in soils contaminated with Cu and Pb. The microbial biomass C:N ratio in the metal contaminated soil was observed to be considerably higher than that in untreated control. Between the two tested metals, Cu displayed greater biocidal effect on microbial biomass carbon and nitrogen than Pb, showing their relative toxicity in the order: Cu≫Pb. Project (No. 49671050) supported by National Natural Science Foundation of China. Wa’el Mohamad—Former Ph. D. Student of Zhejiang University and is working in Ministry Of Agriculture (P. O. box. 2099), Amman, Jordan.  相似文献   

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