TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3A...TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3Al has been evidenced by finding Ni_3(Al,Ti)C after fast cooling in the TiC/Ni_3Al composites. The dissolution may be responsible for the infiltration and sintering. Compared with downward infiltration, the upward infiltration brought about higher strength and fracture toughness and shorter infiltration time. TiC/20 vol. pct Ni_3Al composite processed by upward infiltration had a flexural strength of 1476 MPa with a statistic Weibull modulus of 20.2 and a fracture toughness of 20.4 MPa . Better mechanical properties may be attributed to melt unidirectional movement in upward infiltration.展开更多
BaO is the most common consideration in the preparation of newcrystal glass for getting rid of lead content in the glass andceramic wares to protect hu- man health and environment. But forkeeping the glass products...BaO is the most common consideration in the preparation of newcrystal glass for getting rid of lead content in the glass andceramic wares to protect hu- man health and environment. But forkeeping the glass products' properties to meet the requirements ofthe tradi- tional crystal glass, B_2O_3, Al_2O_3, TiO_2, SrO and ZnOetc (at a special ratio) had been researched with BaO to con- stitutea mixture to replace the lead content in the glass compositions.展开更多
Reaction-milled NiAl-TiB2 composite was fabricated by mechanical alloying elemental powders and hot pressing. TiB2 particles are distributed mostly in grain boundaries of the matrix. The compressive strain to failure ...Reaction-milled NiAl-TiB2 composite was fabricated by mechanical alloying elemental powders and hot pressing. TiB2 particles are distributed mostly in grain boundaries of the matrix. The compressive strain to failure of the composite at RT is about twice that of cast NiAl. The compressive yield stress at high temperatures is about 4.5 times higher than that of extruded NiAl, and is also much stronger than XD NiAl-TiB2 composites. Deformation behavior between 1000~1100℃ with different strain rates has been investigated展开更多
BACKGROUND Many Ayurvedic preparations are claimed to have immune-boosting properties,as suggested in various published randomized clinical trials(RCTs)AIM To compile evidence on the nature and mechanism of immune sys...BACKGROUND Many Ayurvedic preparations are claimed to have immune-boosting properties,as suggested in various published randomized clinical trials(RCTs)AIM To compile evidence on the nature and mechanism of immune system enhancement by Ayurvedic preparations in healthy and sick individuals.METHODS After prospectively registering study protocol with PROSPERO,we searched PubMed,DOAJ,Google Scholar,three dedicated Ayurveda research portals,two specialty Ayurveda journals,and reference lists for relevant records published until February 6,2021 using appropriate search strategies.Baseline features and data pertaining to the nature and mechanism of immune system function were extracted from all eligible records.Methodological quality was assessed using the Cochrane RoB-2 tool.RESULTS Of 12554 articles screened,19 studies reporting 20 RCTs(17 parallel group design,three crossover design)with 1661 unique patients were included;11/19 studies had Indian first authors.Healthy population was included in nine studies,of which one study included pregnant women and two included pediatric population;remaining studies included patients with different health conditions,including one study with coronavirus disease 2019 patients.A total of 21 Ayurvedic interventions were studied,out of which five were composite mixtures.The predominant route of administration was oral;dose and frequency of administration of the intervention varied across the studies.The results reported with five RCTs exploring five Ayurvedic interventions were incomplete,ambiguous,or confusing.Of the remaining 16 interventions,indirect evidence of immune enhancement was reported with four interventions,while lack of the same was reported with two interventions.Enhancement of T helper cells and natural killer cells was reported with three and four interventions,respectively,while the pooled results did not clearly point toward enhancement of other components of the immune system,including cytotoxic T cells,B lymphocytes,immunoglobulins,cytokines,complement components,leucocyte counts,and other components.Nine of the 20 RCTs had a high risk of bias,and the remaining 11 RCTs had some concerns according to RoB-2.CONCLUSION Various Ayurvedic preparations appear to enhance the immune system,particularly via enhancements in natural killer cells and T helper cells.展开更多
Recently, the study of nanocomposites has attracted much attention, but the powder isdifficult to be homogenized and nanoparticles are not well distributed when nanophase isintroduced into matrix via general mechanica...Recently, the study of nanocomposites has attracted much attention, but the powder isdifficult to be homogenized and nanoparticles are not well distributed when nanophase isintroduced into matrix via general mechanical mixing. The in situ formation of AlNsubmicron particles in Al<sub>2</sub>O<sub>3</sub> matrix has been explored to prepare AlN-Al<sub>2</sub>O<sub>3</sub> composite bymeans of reaction-bonding method.展开更多
USLNG CO<sub>2</sub> laser beam as a heat source to sinter whole P/M （powder metallurgy） green com-pact is a new technique. As reported in refs. [1--4], the advantages of the laser sintering ofCu-base an...USLNG CO<sub>2</sub> laser beam as a heat source to sinter whole P/M （powder metallurgy） green com-pact is a new technique. As reported in refs. [1--4], the advantages of the laser sintering ofCu-base and Fe-base green compact were characterized by rapid sintering rate, no contamina-tion, fine structure and good properties.展开更多
文摘TiC/Ni_3Al composites have been prepared using upward infiltration method. The densification was performed by both Ni_3Al melt filling and TiC sintering during the infiltration. The dissolution of TiC in liquid Ni_3Al has been evidenced by finding Ni_3(Al,Ti)C after fast cooling in the TiC/Ni_3Al composites. The dissolution may be responsible for the infiltration and sintering. Compared with downward infiltration, the upward infiltration brought about higher strength and fracture toughness and shorter infiltration time. TiC/20 vol. pct Ni_3Al composite processed by upward infiltration had a flexural strength of 1476 MPa with a statistic Weibull modulus of 20.2 and a fracture toughness of 20.4 MPa . Better mechanical properties may be attributed to melt unidirectional movement in upward infiltration.
基金Supported by the Youth Foundation of Beijing Graduate School of Wuhan University of Technology(No.97-QW)
文摘BaO is the most common consideration in the preparation of newcrystal glass for getting rid of lead content in the glass andceramic wares to protect hu- man health and environment. But forkeeping the glass products' properties to meet the requirements ofthe tradi- tional crystal glass, B_2O_3, Al_2O_3, TiO_2, SrO and ZnOetc (at a special ratio) had been researched with BaO to con- stitutea mixture to replace the lead content in the glass compositions.
文摘Reaction-milled NiAl-TiB2 composite was fabricated by mechanical alloying elemental powders and hot pressing. TiB2 particles are distributed mostly in grain boundaries of the matrix. The compressive strain to failure of the composite at RT is about twice that of cast NiAl. The compressive yield stress at high temperatures is about 4.5 times higher than that of extruded NiAl, and is also much stronger than XD NiAl-TiB2 composites. Deformation behavior between 1000~1100℃ with different strain rates has been investigated
文摘BACKGROUND Many Ayurvedic preparations are claimed to have immune-boosting properties,as suggested in various published randomized clinical trials(RCTs)AIM To compile evidence on the nature and mechanism of immune system enhancement by Ayurvedic preparations in healthy and sick individuals.METHODS After prospectively registering study protocol with PROSPERO,we searched PubMed,DOAJ,Google Scholar,three dedicated Ayurveda research portals,two specialty Ayurveda journals,and reference lists for relevant records published until February 6,2021 using appropriate search strategies.Baseline features and data pertaining to the nature and mechanism of immune system function were extracted from all eligible records.Methodological quality was assessed using the Cochrane RoB-2 tool.RESULTS Of 12554 articles screened,19 studies reporting 20 RCTs(17 parallel group design,three crossover design)with 1661 unique patients were included;11/19 studies had Indian first authors.Healthy population was included in nine studies,of which one study included pregnant women and two included pediatric population;remaining studies included patients with different health conditions,including one study with coronavirus disease 2019 patients.A total of 21 Ayurvedic interventions were studied,out of which five were composite mixtures.The predominant route of administration was oral;dose and frequency of administration of the intervention varied across the studies.The results reported with five RCTs exploring five Ayurvedic interventions were incomplete,ambiguous,or confusing.Of the remaining 16 interventions,indirect evidence of immune enhancement was reported with four interventions,while lack of the same was reported with two interventions.Enhancement of T helper cells and natural killer cells was reported with three and four interventions,respectively,while the pooled results did not clearly point toward enhancement of other components of the immune system,including cytotoxic T cells,B lymphocytes,immunoglobulins,cytokines,complement components,leucocyte counts,and other components.Nine of the 20 RCTs had a high risk of bias,and the remaining 11 RCTs had some concerns according to RoB-2.CONCLUSION Various Ayurvedic preparations appear to enhance the immune system,particularly via enhancements in natural killer cells and T helper cells.
文摘Recently, the study of nanocomposites has attracted much attention, but the powder isdifficult to be homogenized and nanoparticles are not well distributed when nanophase isintroduced into matrix via general mechanical mixing. The in situ formation of AlNsubmicron particles in Al<sub>2</sub>O<sub>3</sub> matrix has been explored to prepare AlN-Al<sub>2</sub>O<sub>3</sub> composite bymeans of reaction-bonding method.
文摘USLNG CO<sub>2</sub> laser beam as a heat source to sinter whole P/M （powder metallurgy） green com-pact is a new technique. As reported in refs. [1--4], the advantages of the laser sintering ofCu-base and Fe-base green compact were characterized by rapid sintering rate, no contamina-tion, fine structure and good properties.
