AIM: To explore the anti-fibrotic effect of a traditional Chinese medicine, compound rhodiola sachalinensis A Bor on CCl4-induced liver fibrosis in rats and its probable molecular mechanisms. METHODS: Ninety healthy m...AIM: To explore the anti-fibrotic effect of a traditional Chinese medicine, compound rhodiola sachalinensis A Bor on CCl4-induced liver fibrosis in rats and its probable molecular mechanisms. METHODS: Ninety healthy male SD rats were randomly divided into three groups: normal group (n=-10), treatment group of compound rhodiola sachalinensis A Bor (n=-40) and CCl4-induced model group (n=40). The liver fibrosis was induced by CCl4 subcutaneous injection. Treatment group was administered with compound rhodiola sachalinensis A Bor (0.5 g/kg) once a day at the same time. Then the activities of several serum fibrosis-associated enzymes: alanine aminotransferase (ALT), aspartate aminotransferase (AST), N-acetyl-beta-D-glucosaminidase (β-NAG) and the levels ofserum procollagen Ⅲ (PCⅢ), collagen Ⅳ (CⅣ), hyaluronic acid （HA） were assayed. The histooathol(mical chanaes were observed with HE, VG and Masson stain. The expression of TGF-β1 mRNA,αl (I) mRNA and Na+/Ca2+ exchanger (NCX ) mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) in situ.RESULTS: Compound rhodiola sachalinensis A Bor significantly reduced serum activities of ALT, AST, β-NAG and decreased the levels of PCⅢ, CⅣ, HA, improved the liver histopathological changes, inhibited the expression of TGF-β1 mRNA, α(1) mRNA and Na+/Ca2+ exchanger mRNA in rats. CONCLUSION: Compound rhodiola sachalinensis A Bor can intervene in CCI4-induced liver fibrosis in rats, in which potential mechanisms may be decreasing the production of TGF-β1, reducing the production of collagen, preventing the activation of hepatic stellate cell (HSC) and inhibiting theexpression of TGF-β1 mRNA, αl(I) mRNA and Na+/Ca2+ exchanger mRNA.展开更多
AIM: To reduce the incidence of postoperative anastomoticleak, stenosis, gastroesophageal reflux (GER) for patientswith esophageal carcinoma, and to evaluate the conventionalmethod of esophagectomy and esophagogastrop...AIM: To reduce the incidence of postoperative anastomoticleak, stenosis, gastroesophageal reflux (GER) for patientswith esophageal carcinoma, and to evaluate the conventionalmethod of esophagectomy and esophagogastroplastymodified by a new three-layer-funnel-shaped (TLF)esophagogastric anastomotic suturing technique.METHODS: From January 1997 to October 1999, patientswith clinical stage Ⅰ and Ⅱ (Ⅱa and Ⅱb) esophagealcarcinoma, which met the enrollment criteria, were surgicallytreated by the new method (Group A) and by conventionaloperation (Group B). All the patients were followed at leastfor 6 months. Postoperative outcomes and complicationswere recorded and compared with the conventional methodin the same hospitals and with that reported previously byMcLarty etalin 1997 (Group C).RESULTS: 58 cases with stage Ⅰ and Ⅱ (Ⅱa and Ⅱb)esophageal carcinoma, including 38 males and 20 femalesaged from 34 to 78 (mean age: 57), were surgically treatedby the TLF anastomosis and 64 by conventional method inour hospitals from January 1997 to October 1999. The qualityof swallowing was improved significantly (Wilcoxon W＝2 142,P＝0.0 001) 2 to 3 months after the new operation in GroupA. Only one patient had a blind anastomatic fistula diagnosedby barium swallow test 2 months but healed up 3 weekslater. Postoperative complications occurred in 25 (43 %)patients, anastomotic stenosis in 8 (14 %), and GER in 13(22 %). The incidences of postoperative anastomotic leak,stenosis and GER were significantly decreased by the TLFanastomosis method compared with that of conventionalmethods (x2＝6.566, P ＝0.038; x2＝10.214, P＝ 0.006;x2＝21.265, P＝0.000).CONCLUSION: The new three-layer-funnel-shapedesophagogastric anastomosis (TLFEGA) hasmore advantagesto reduce postoperative complications of anastomotic leak,stricture and GER.展开更多
OBJECTIVE To investigate the mechanisms of Xiaobanxia Tang(XBXT)in the prevention and treatment of chemotherapy-induced nausea and vomiting.METHODS The chemotherapy-induced rat pica model was established by intraperit...OBJECTIVE To investigate the mechanisms of Xiaobanxia Tang(XBXT)in the prevention and treatment of chemotherapy-induced nausea and vomiting.METHODS The chemotherapy-induced rat pica model was established by intraperitoneal injection of cisplatin 6mg·kg-1.Kaolin consumption was used as an indicator of nausea and vomiting.Wistar male rats were randomly divided into normal control,XBXT normal control,model,ondansetron treating,XBXT decoction high and low dose groups.The rats in ondansetron group,XBXT normal control group,XBXT high and low dose groups were gavaged ondansetron 2.6mg·kg-1·d-1,XBXT 1.6,3.2and 1.6g·kg-1·d-1,respectively 1hbefore cisplatin injection,and the administration were given every 12 h.Kaolin consumptions were weighed every 12 h.After 24 hand 72hof cisplatin injection,animals were sacrificed respectively.The contents of 5-HT,5-HIAA,dopamine(DA),DOPAC,substance P(SP),TPH,MAO and TH were measured by ELISA.The mRNA expression of 5-HT transporter(SERT),5-HT3 Areceptor,SP precursor(PPTA),NK1 and D2receptors in rat ileum and medulla oblongata were measured by RT-PCR,the protein expression were measured by Western blotting.RESULTS The high and low dosages of XBXT could significantly inhibit kaolin consumptions in cisplatin-treated rats,and reduce5-HT,increase 5-HIAA contents and reduce 5-HT3 Areceptor mRNA and protein expression,above effects are related to the reduction of TPH and the enhancement of MAOA levels.The two dosages of XBXT could significantly reduce SP and NK1 mRNA and protein expression,which was related to the reduction of PPTA mRNA expression.XBXT could also significantly reduce DA contents and D2 receptor mRNA and protein expression,which was related to the reduction of TH.CONCLUSION XBXT has significant antiemetic effect in chemotherapy-induced nausea and vomiting,the underlying mechanisms are related to the inhibition of 5-HT and5-HT3 Areceptor,SP and NK1 receptor,DA and D2 receptor.展开更多
A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) -...A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) - 900 mmol/L butanol - 10 mmol/L borate at pH 9.4 and a pressure-driven flow of 0.020 mL/min under 1.3 MPa was employed to manipulate the separation. Explosives HMX (1, 3, 5, 7-tetranitro-l, 3, 5, 7-tetrazacyclooctane) and TATB (triamino-trinitrobenzene), which were felted on fluorine rubber F2311 (polytrifluorochlorethylene and polyvinylidene fluoride 1/1 co-polymerization) and F2314 (polytrifluorochlorethylene and polyvinylidene fluoride 4/1 co-polymerization) were well separated with very good peak shapes.展开更多
AZ91D magnesium alloy rolled under four rolling conditions,namely cold rolling,electric pulsecold rolling,hot rolling and electric pulse hot rolling,and the first principles calculation of Mg with or without external ...AZ91D magnesium alloy rolled under four rolling conditions,namely cold rolling,electric pulsecold rolling,hot rolling and electric pulse hot rolling,and the first principles calculation of Mg with or without external electric field carried out.The results show that:The application of pulse current in the rolling process of AZ91D magnesium alloy can effectively improve the edge crack of the sample,optimize the texture of AZ91D magnesium alloy and reduce its texture strength,promote the generation of tensile twins and the transition from small Angle grain boundaries to large Angle grain boundaries,and thus improve the plastic forming ability of AZ91D magnesium alloy.Make it more prone to plastic deformation.Compared with ordinary rolling,the microhardness ofα-Mg matrix decreases by 15%.The tensile strength and elongation increased from 137MPa and 3.4%to 169MPa and 4.7%,respectively.The results show that the stiffness of Mg decreases and the Poisson's ratio of Mg increases when the electric field applies.When the B/G value is greater than 1.75,the plasticity of Mg is improved.The fault energy at the base surface of Mg does not change much,while the fault energy at the prismatic surface of Mg decreases obviously,showing the external electric field mainly affects the prismatic surface slip of Mg,which makes the prismatic surface slip easier to start,and thus improves the plastic forming ability of Mg.展开更多
To investigate the significance of the SARS-associated coronavirus (SARS-CoV) antibody,detected by ELISA and indirect immunofluorescence assays (IFA) for the SARS-CoV Vero E6 cell lysates,in non-SARS subjects, 114 ser...To investigate the significance of the SARS-associated coronavirus (SARS-CoV) antibody,detected by ELISA and indirect immunofluorescence assays (IFA) for the SARS-CoV Vero E6 cell lysates,in non-SARS subjects, 114 serum samples from healthy controls and 104 serum specimens from autoimmune disease patients were collected.The results of ELISA showed that among 114 sera from healthy controls,4 (3.5%) were positive of SARS-CoV-IgG antibody and 114 (100%) were all negative of SARS-CoV-IgM antibody;the specificity of SARS-CoV-IgG antibody for SARS patients was 96.5%,but the specificity of both SARS-CoV-IgG and -IgM antibodies for SARS patients was 100%.In 58 cases with SLE,positive rates of SARS-CoV-IgG and -IgM antibodies were 32.8% (19/58) and 8.6% (5/58),respectively,in which 11 cases (19%) were positive of both SARS-CoV-IgG and -IgM antibodies;in 10 cases with SS,positive rate of both SARS-CoV-IgG and -IgM antibodies was 10% (1/10);in 16 cases with MCTD,positive rate of SARS-CoV-IgG was 37.5% (6/16),positive rate of both SARS-CoV-IgG and -IgM antibodies was 6.3% (1/16);in 20 cases with RA,one case was positive (5%) of SARS-CoV-IgG.However,of all samples with positive SARS-CoV-IgG and -IgM antibodies for autoimmune diseases and healthy controls,SARS-CoV RNA and antibodies were all negative by RT-PCR and IFA.All sera for negative or positive ELISA results were also negative or positive results using ELISA with Vero E6 cells lysates.These studies showed that SARS-CoV Vero E6 cell lysates for the ELISA to detect SARS-CoV antibodies could lead to the false-positive reactions or cross-reactions of SARS-CoV antibodies in non-SARS diseases and healthy controls,and the false-positive reactions or cross-reactions were related to Vero E6 cell lysates and autoantibodies in non-SARS population.Cellular & Molecular Immunology.2004;1(4): 304-307.展开更多
The problem of efficiently monitoring the network flow is regarded as the problem to find out the minimum weighted weak vertex cover set for a given graphG=(V,E). In this paper, we give an approximation algorithm to s...The problem of efficiently monitoring the network flow is regarded as the problem to find out the minimum weighted weak vertex cover set for a given graphG=(V,E). In this paper, we give an approximation algorithm to solve it, which has the approximation ratio lnd+1, whered is the maximum degree of the vertex in graphG, and improve the previous work. Keywords weak vertex cover - NP-hard - approximation algorithm NoteThis work is supported by the Ministry of Science and Technology of China (Grant No.2001CCA03000), the National Natural Science Foundation of China (Grant No.60273045), and the Shanghai Science and Technology Development Foundation (Grant No.025115032).展开更多
Nanosized palladium particles were incorporated into mesoporous silica matrix to obtain nanocomposites using the sol-gel technique. Effects of the finely dispersed metallic palladium on the microstructure and properti...Nanosized palladium particles were incorporated into mesoporous silica matrix to obtain nanocomposites using the sol-gel technique. Effects of the finely dispersed metallic palladium on the microstructure and properties of the nanocomposites were investigated. By means of X-ray diffraction and optical absorption, it was found that palladium particles were 5~9 nm in diameter and their uniform dispersion in the mesoporous silica depended on both the content of the palladium and the structural features of the silica matrix. The results showed that the mixing method of preparation led to wider size distribution of the nanosized particles as compared to the immersion method, but dispersed degree was reduced. Although the incorporation of nanosized palladium particles could not substantially induce significant structural changes of the matrix, the apparent red-shifted optical absorptions for the nanocomposites were observed as compared to the parent monolithic silica, particularly with increase in palladium loading and calcination temperature.展开更多
Networked silicon oxide nanowires have been synthesized by VO2-assisted chemical vapor deposition at 1000 ~C on silicon substrate without supplying any gaseous or liquid Si source. Systematic study on the nanowire gro...Networked silicon oxide nanowires have been synthesized by VO2-assisted chemical vapor deposition at 1000 ~C on silicon substrate without supplying any gaseous or liquid Si source. Systematic study on the nanowire growth has indicated that morphology and composition of the final products are sensitive to the catalyst components, reaction atmosphere and temperature. Compared to Au and V02 as catalysts individually, co-catalysts of Au and V02 play a critical role in the formation of networked Si02 nanowires. Transmission electron microscopy （TEM） and scanning electron microscopy （SEM） observations indicate that the silicon oxide nanowires have smooth surfaces with uniform diameters of 30-100 rim, and their lengths reach several hundred micrometers. X-ray photoelectron spectroscopy （XPS） results reveal the atomic ratio of silicon to oxygen is about 1：2. Growth dependence of the networked nanowires on hydrogen and temperature is also discussed. Vapor-liquid-solid （VLS） process is proposed for the growth mechanism of the networked nanowires. It is also found that the growth mechanism of SiO2 nanowires by increasing the temperature up to 1200 ℃ changes to vapor-solid （VS） processes since wire-like structures can be formed without any catalyst or H2 gas introduced into the system.展开更多
基金the Tenth-Five Year Plan of Medical Science Foundation of Chengdu Military Command,No.01A009
文摘AIM: To explore the anti-fibrotic effect of a traditional Chinese medicine, compound rhodiola sachalinensis A Bor on CCl4-induced liver fibrosis in rats and its probable molecular mechanisms. METHODS: Ninety healthy male SD rats were randomly divided into three groups: normal group (n=-10), treatment group of compound rhodiola sachalinensis A Bor (n=-40) and CCl4-induced model group (n=40). The liver fibrosis was induced by CCl4 subcutaneous injection. Treatment group was administered with compound rhodiola sachalinensis A Bor (0.5 g/kg) once a day at the same time. Then the activities of several serum fibrosis-associated enzymes: alanine aminotransferase (ALT), aspartate aminotransferase (AST), N-acetyl-beta-D-glucosaminidase (β-NAG) and the levels ofserum procollagen Ⅲ (PCⅢ), collagen Ⅳ (CⅣ), hyaluronic acid （HA） were assayed. The histooathol(mical chanaes were observed with HE, VG and Masson stain. The expression of TGF-β1 mRNA,αl (I) mRNA and Na+/Ca2+ exchanger (NCX ) mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) in situ.RESULTS: Compound rhodiola sachalinensis A Bor significantly reduced serum activities of ALT, AST, β-NAG and decreased the levels of PCⅢ, CⅣ, HA, improved the liver histopathological changes, inhibited the expression of TGF-β1 mRNA, α(1) mRNA and Na+/Ca2+ exchanger mRNA in rats. CONCLUSION: Compound rhodiola sachalinensis A Bor can intervene in CCI4-induced liver fibrosis in rats, in which potential mechanisms may be decreasing the production of TGF-β1, reducing the production of collagen, preventing the activation of hepatic stellate cell (HSC) and inhibiting theexpression of TGF-β1 mRNA, αl(I) mRNA and Na+/Ca2+ exchanger mRNA.
文摘AIM: To reduce the incidence of postoperative anastomoticleak, stenosis, gastroesophageal reflux (GER) for patientswith esophageal carcinoma, and to evaluate the conventionalmethod of esophagectomy and esophagogastroplastymodified by a new three-layer-funnel-shaped (TLF)esophagogastric anastomotic suturing technique.METHODS: From January 1997 to October 1999, patientswith clinical stage Ⅰ and Ⅱ (Ⅱa and Ⅱb) esophagealcarcinoma, which met the enrollment criteria, were surgicallytreated by the new method (Group A) and by conventionaloperation (Group B). All the patients were followed at leastfor 6 months. Postoperative outcomes and complicationswere recorded and compared with the conventional methodin the same hospitals and with that reported previously byMcLarty etalin 1997 (Group C).RESULTS: 58 cases with stage Ⅰ and Ⅱ (Ⅱa and Ⅱb)esophageal carcinoma, including 38 males and 20 femalesaged from 34 to 78 (mean age: 57), were surgically treatedby the TLF anastomosis and 64 by conventional method inour hospitals from January 1997 to October 1999. The qualityof swallowing was improved significantly (Wilcoxon W＝2 142,P＝0.0 001) 2 to 3 months after the new operation in GroupA. Only one patient had a blind anastomatic fistula diagnosedby barium swallow test 2 months but healed up 3 weekslater. Postoperative complications occurred in 25 (43 %)patients, anastomotic stenosis in 8 (14 %), and GER in 13(22 %). The incidences of postoperative anastomotic leak,stenosis and GER were significantly decreased by the TLFanastomosis method compared with that of conventionalmethods (x2＝6.566, P ＝0.038; x2＝10.214, P＝ 0.006;x2＝21.265, P＝0.000).CONCLUSION: The new three-layer-funnel-shapedesophagogastric anastomosis (TLFEGA) hasmore advantagesto reduce postoperative complications of anastomotic leak,stricture and GER.
基金The project supported by National Natural Science Foundation of China(81373828)
文摘OBJECTIVE To investigate the mechanisms of Xiaobanxia Tang(XBXT)in the prevention and treatment of chemotherapy-induced nausea and vomiting.METHODS The chemotherapy-induced rat pica model was established by intraperitoneal injection of cisplatin 6mg·kg-1.Kaolin consumption was used as an indicator of nausea and vomiting.Wistar male rats were randomly divided into normal control,XBXT normal control,model,ondansetron treating,XBXT decoction high and low dose groups.The rats in ondansetron group,XBXT normal control group,XBXT high and low dose groups were gavaged ondansetron 2.6mg·kg-1·d-1,XBXT 1.6,3.2and 1.6g·kg-1·d-1,respectively 1hbefore cisplatin injection,and the administration were given every 12 h.Kaolin consumptions were weighed every 12 h.After 24 hand 72hof cisplatin injection,animals were sacrificed respectively.The contents of 5-HT,5-HIAA,dopamine(DA),DOPAC,substance P(SP),TPH,MAO and TH were measured by ELISA.The mRNA expression of 5-HT transporter(SERT),5-HT3 Areceptor,SP precursor(PPTA),NK1 and D2receptors in rat ileum and medulla oblongata were measured by RT-PCR,the protein expression were measured by Western blotting.RESULTS The high and low dosages of XBXT could significantly inhibit kaolin consumptions in cisplatin-treated rats,and reduce5-HT,increase 5-HIAA contents and reduce 5-HT3 Areceptor mRNA and protein expression,above effects are related to the reduction of TPH and the enhancement of MAOA levels.The two dosages of XBXT could significantly reduce SP and NK1 mRNA and protein expression,which was related to the reduction of PPTA mRNA expression.XBXT could also significantly reduce DA contents and D2 receptor mRNA and protein expression,which was related to the reduction of TH.CONCLUSION XBXT has significant antiemetic effect in chemotherapy-induced nausea and vomiting,the underlying mechanisms are related to the inhibition of 5-HT and5-HT3 Areceptor,SP and NK1 receptor,DA and D2 receptor.
文摘A new MEEKC method assisted with pressure-driven mobile phase was presented for the separation of felted explosives. Microemulsion solution was composed of 80 mmol/L heptane -120 mmol/L SDS (sodium dodecyl sulphate) - 900 mmol/L butanol - 10 mmol/L borate at pH 9.4 and a pressure-driven flow of 0.020 mL/min under 1.3 MPa was employed to manipulate the separation. Explosives HMX (1, 3, 5, 7-tetranitro-l, 3, 5, 7-tetrazacyclooctane) and TATB (triamino-trinitrobenzene), which were felted on fluorine rubber F2311 (polytrifluorochlorethylene and polyvinylidene fluoride 1/1 co-polymerization) and F2314 (polytrifluorochlorethylene and polyvinylidene fluoride 4/1 co-polymerization) were well separated with very good peak shapes.
基金The work was supported by the National Natural Science Foundation of China[grant number52061002].
文摘AZ91D magnesium alloy rolled under four rolling conditions,namely cold rolling,electric pulsecold rolling,hot rolling and electric pulse hot rolling,and the first principles calculation of Mg with or without external electric field carried out.The results show that:The application of pulse current in the rolling process of AZ91D magnesium alloy can effectively improve the edge crack of the sample,optimize the texture of AZ91D magnesium alloy and reduce its texture strength,promote the generation of tensile twins and the transition from small Angle grain boundaries to large Angle grain boundaries,and thus improve the plastic forming ability of AZ91D magnesium alloy.Make it more prone to plastic deformation.Compared with ordinary rolling,the microhardness ofα-Mg matrix decreases by 15%.The tensile strength and elongation increased from 137MPa and 3.4%to 169MPa and 4.7%,respectively.The results show that the stiffness of Mg decreases and the Poisson's ratio of Mg increases when the electric field applies.When the B/G value is greater than 1.75,the plasticity of Mg is improved.The fault energy at the base surface of Mg does not change much,while the fault energy at the prismatic surface of Mg decreases obviously,showing the external electric field mainly affects the prismatic surface slip of Mg,which makes the prismatic surface slip easier to start,and thus improves the plastic forming ability of Mg.
文摘To investigate the significance of the SARS-associated coronavirus (SARS-CoV) antibody,detected by ELISA and indirect immunofluorescence assays (IFA) for the SARS-CoV Vero E6 cell lysates,in non-SARS subjects, 114 serum samples from healthy controls and 104 serum specimens from autoimmune disease patients were collected.The results of ELISA showed that among 114 sera from healthy controls,4 (3.5%) were positive of SARS-CoV-IgG antibody and 114 (100%) were all negative of SARS-CoV-IgM antibody;the specificity of SARS-CoV-IgG antibody for SARS patients was 96.5%,but the specificity of both SARS-CoV-IgG and -IgM antibodies for SARS patients was 100%.In 58 cases with SLE,positive rates of SARS-CoV-IgG and -IgM antibodies were 32.8% (19/58) and 8.6% (5/58),respectively,in which 11 cases (19%) were positive of both SARS-CoV-IgG and -IgM antibodies;in 10 cases with SS,positive rate of both SARS-CoV-IgG and -IgM antibodies was 10% (1/10);in 16 cases with MCTD,positive rate of SARS-CoV-IgG was 37.5% (6/16),positive rate of both SARS-CoV-IgG and -IgM antibodies was 6.3% (1/16);in 20 cases with RA,one case was positive (5%) of SARS-CoV-IgG.However,of all samples with positive SARS-CoV-IgG and -IgM antibodies for autoimmune diseases and healthy controls,SARS-CoV RNA and antibodies were all negative by RT-PCR and IFA.All sera for negative or positive ELISA results were also negative or positive results using ELISA with Vero E6 cells lysates.These studies showed that SARS-CoV Vero E6 cell lysates for the ELISA to detect SARS-CoV antibodies could lead to the false-positive reactions or cross-reactions of SARS-CoV antibodies in non-SARS diseases and healthy controls,and the false-positive reactions or cross-reactions were related to Vero E6 cell lysates and autoantibodies in non-SARS population.Cellular & Molecular Immunology.2004;1(4): 304-307.
文摘The problem of efficiently monitoring the network flow is regarded as the problem to find out the minimum weighted weak vertex cover set for a given graphG=(V,E). In this paper, we give an approximation algorithm to solve it, which has the approximation ratio lnd+1, whered is the maximum degree of the vertex in graphG, and improve the previous work. Keywords weak vertex cover - NP-hard - approximation algorithm NoteThis work is supported by the Ministry of Science and Technology of China (Grant No.2001CCA03000), the National Natural Science Foundation of China (Grant No.60273045), and the Shanghai Science and Technology Development Foundation (Grant No.025115032).
文摘Nanosized palladium particles were incorporated into mesoporous silica matrix to obtain nanocomposites using the sol-gel technique. Effects of the finely dispersed metallic palladium on the microstructure and properties of the nanocomposites were investigated. By means of X-ray diffraction and optical absorption, it was found that palladium particles were 5~9 nm in diameter and their uniform dispersion in the mesoporous silica depended on both the content of the palladium and the structural features of the silica matrix. The results showed that the mixing method of preparation led to wider size distribution of the nanosized particles as compared to the immersion method, but dispersed degree was reduced. Although the incorporation of nanosized palladium particles could not substantially induce significant structural changes of the matrix, the apparent red-shifted optical absorptions for the nanocomposites were observed as compared to the parent monolithic silica, particularly with increase in palladium loading and calcination temperature.
基金supported by Natural Sciences and Engineering Research Council of Canada (NSERC)Canadian Space Agency,NSERC Canada Research Chair (CRC) Program+3 种基金Canada Foundation for Innovation (CFI)Ontario Research Fund (ORF)Ontario Early Researcher Award (ERA)the University of Western Ontario
文摘Networked silicon oxide nanowires have been synthesized by VO2-assisted chemical vapor deposition at 1000 ~C on silicon substrate without supplying any gaseous or liquid Si source. Systematic study on the nanowire growth has indicated that morphology and composition of the final products are sensitive to the catalyst components, reaction atmosphere and temperature. Compared to Au and V02 as catalysts individually, co-catalysts of Au and V02 play a critical role in the formation of networked Si02 nanowires. Transmission electron microscopy （TEM） and scanning electron microscopy （SEM） observations indicate that the silicon oxide nanowires have smooth surfaces with uniform diameters of 30-100 rim, and their lengths reach several hundred micrometers. X-ray photoelectron spectroscopy （XPS） results reveal the atomic ratio of silicon to oxygen is about 1：2. Growth dependence of the networked nanowires on hydrogen and temperature is also discussed. Vapor-liquid-solid （VLS） process is proposed for the growth mechanism of the networked nanowires. It is also found that the growth mechanism of SiO2 nanowires by increasing the temperature up to 1200 ℃ changes to vapor-solid （VS） processes since wire-like structures can be formed without any catalyst or H2 gas introduced into the system.
