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Bioaccumulation of heavy metals in fishes from Taihu Lake,China 被引量:13
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作者 CHI Qiao-qiao ZHU Guang-wei Alan langdon 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2007年第12期1500-1504,共5页
The Cr, Zn, Cu, Cd, Pb contents were determined in Cyprinus carpio Linnaeus, Carassius auratus Linnaeus, Hypophthalmichthys molitrix and Aristichthys nobilis, which were caught from Meiliang Bay, Taihu Lake, a large, ... The Cr, Zn, Cu, Cd, Pb contents were determined in Cyprinus carpio Linnaeus, Carassius auratus Linnaeus, Hypophthalmichthys molitrix and Aristichthys nobilis, which were caught from Meiliang Bay, Taihu Lake, a large, shallow and eutrophic lake of China. The results showed that: (1) the Cr, Cu, Pb, Cd contents in the edible parts of the four fish species were much lower than Chinese Food Health Criterion (1994), but the Zn contents were higher than the Criterion; (2) Cd contents were the highest in the liver of fish, Pb contents were almost the same in all organs of fish, Cr contents mainly enriched in the skin and gonads, Zn contents were the highest in the gonad (♀), and Cu contents were the highest in the liver; (3) the total metal accumulation was the greatest in the liver and the lowest in the muscle. The total metal accumulation was the highest in C. auratus L. This investigation indicated that fish products in Taihu Lake were still safe for human consumption, but the amount consumed should be controlled under the Chinese Food Health Criterion to avoid excessive intake of Zn. 展开更多
关键词 FISH heavy metals BIOACCUMULATION food safety Taihu Lake
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Spatially Different Nutrient Histories Recorded by Multiple Cores and Implications for Management in Taihu Lake, Eastern China 被引量:4
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作者 CAO Yanmin ZHANG Enlou +2 位作者 Peter langdon LIU Enfeng SHEN Ji 《Chinese Geographical Science》 SCIE CSCD 2013年第5期537-549,共13页
The Taihu Lake,a large shallow lake in the floodplain of the Changjiang(Yangtze) River in the eastern China,is faced with challenging ecological problems resulting from eutrophication,which has affected the regional f... The Taihu Lake,a large shallow lake in the floodplain of the Changjiang(Yangtze) River in the eastern China,is faced with challenging ecological problems resulting from eutrophication,which has affected the regional freshwater supply of a large population.Although efforts have been made to assess the nutrient evolution histories in the northern bays,little is known regarding nutrient histories in different parts across the entire lake basin.In this paper,we present nutrient histories for different parts of the lake based on chironomid transfer functions applied to four short cores obtained from the northern,western and eastern regions of the lake.The chironomid-inferred total phosphorus(CI-TP) concentrations were compared with the phosphorus concentrations obtained by using instrumental and sedimentary data.The results suggest that trophic evolution histories were asynchronous throughout the lake during the past decades in response to different ecological regimes controlled by the nutrient input,wind direction and shoreline topography.The restoration of aquatic plants may be an effective option for the management of lake rehabilitation to ′natural′ conditions.Given the multiple factors controlling the biotic communities in such a large and complex lake,combined analyses among the multi-proxies encountered in the sediments are necessary for comprehensive insight into paleolimnological studies.The spatial heterogeneity in the ecological trajectories within this complicated ecosystem suggests that different management practices should be undertaken for specific lake zones in the Taihu Lake. 展开更多
关键词 nutrient history CHIRONOMID multiple cores transfer function Taihu Lake
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Effects of Spent Craft Brewers’ Yeast on Fermentation and Methane Production by Rumen Microorganisms 被引量:1
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作者 Virginia L. Pszczolkowski Robert W. Bryant +3 位作者 Brittany E. Harlow Glen E. Aiken langdon J. Martin Michael D. Flythe 《Advances in Microbiology》 2016年第9期716-723,共9页
Saccharomyces cerevisiae is a key component of beer brewing and a major by-product. The leftover, spent brewers’ yeast from large breweries has been used as a protein supplement in cattle;however the possible advanta... Saccharomyces cerevisiae is a key component of beer brewing and a major by-product. The leftover, spent brewers’ yeast from large breweries has been used as a protein supplement in cattle;however the possible advantages of spent yeast from smaller craft breweries, containing much higher levels of bioactive hop acids, have not been evaluated. Hops secondary metabolites from the hops (Humulus lupulus L.) used to make beer are concentrated in the yeast during brewing, and have antimicrobial activity against Gram-positive bacteria. Uncultivated suspensions of bovine rumen microorganisms produced less methane during fructose fermentation when exposed to inactivated, and freeze-dried spent craft brewers’ yeast than a bakers’ yeast control. The experiment was repeated with caprine rumen microorganisms and ground grass hay as the substrate. Likewise, in the presence of craft brewers’ yeast less methane was produced (2.7% vs. 6.9% CH<sub>4</sub>). Both experiments also revealed a decrease in acetic acid production, but not propionic acid production, when craft brewers’ yeast was included. These results indicated that spent yeast could represent a co-product for craft breweries, and a feed supplement for ruminants that has a favorable impact on methane production. 展开更多
关键词 Antimicrobials BREWING Co-Product Feed Supplement Feed Efficiency Hops Acids Humulus Lupulus Plant Secondary Metabolite PHYTOCHEMICALS
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The effect of moment arm length on high angled femoral neck fractures (Pauwels’ III) 被引量:3
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作者 Matthew S. LePine William R. Barfield +1 位作者 John D. DesJardins langdon A. Hartsock 《Journal of Biomedical Science and Engineering》 2010年第5期448-453,共6页
This study investigated loads among five fixation types (FT) [three cannulated screws (CS), dynamic hip screws with and without derotational screws (DHS-DS and DHS), and dynamic helical hip screws with and without der... This study investigated loads among five fixation types (FT) [three cannulated screws (CS), dynamic hip screws with and without derotational screws (DHS-DS and DHS), and dynamic helical hip screws with and without derotational screws (DHHS-DS and DHHS)] across three fracture moment lengths (ML) in Pauwels’ Type III fractures. Methods: Seventy-five sawbones were tested (5 FT × 5 trials × 3 ML). The study hypothesis was that significant differences in axial loading to failure would be demonstrated when CS was compared with the other four FT at the three MLs. Each construct was exposed to an axial compressive load to failure. Construct failure was defined as 5 mm of migration at the fracture site or fixation failure. Shapiro-Wilk was used to test for data normality. Subsequently, independent t-tests with Bonferroni correction was used for paired comparisons. Results: At fracture Moments A and B there were no statistical differences between CS and the other FT. At fracture Moment C all four FT yielded significantly higher (p ≤ 0.001) loads compared with CS. Conclusions: for basicervical fractures CS is a suboptimal form of fixation compared with DHS and DHHS both with and without derotation screws. 展开更多
关键词 Pauwels’ FRACTURE BIOMECHANICAL TESTING FIXATION
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Influence of Adjuvants on the Control of Glyphosate-Resistant Canada Fleabane and Waterhemp in Corn with Tolpyralate 被引量:2
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作者 Nicole M. langdon Nader Soltani +3 位作者 Alan J. Raedar David C. Hooker Darren E. Robinson Peter H. Sikkema 《American Journal of Plant Sciences》 2020年第3期354-371,共18页
Tolpyralate is a new benzoylpyrazole herbicide for weed management in corn. It is recommended to be co-applied with atrazine along with the adjuvants methylated seed oil concentrate (MSO) plus an ammonium nitrogen fer... Tolpyralate is a new benzoylpyrazole herbicide for weed management in corn. It is recommended to be co-applied with atrazine along with the adjuvants methylated seed oil concentrate (MSO) plus an ammonium nitrogen fertilizer, such as urea ammonium nitrate (UAN). Two studies were conducted on glyphosate-resistant (GR) Canada fleabane and GR waterhemp to determine if an additional adjuvant is still required when tolpyralate plus atrazine are tankmixed with a commercial glyphosate formulation (Roundup WeatherMAX&reg;) in corn. Trials were conducted over a two-year period (2018-19) on farms in south western Ontario with confirmed GR populations. When co-applied with Roundup WeatherMAX&reg;, the addition of MSO to tolpyralate + atrazine increased control of GR waterhemp 9%;however, there was no increase in GR Canada fleabane control from the addition of additional adjuvants. At 8 WAA, all treatments provided > 91% and > 84% control of GR waterhemp and GR Canada fleabane, respectively. This study concludes that the addition of Roundup WeatherMAX&reg;to tolpyralate plus atrazine improves the control of GR waterhemp and GR Canada fleabane in corn. 展开更多
关键词 Biomass Crop Injury Density Sensitivity WEED CONTROL Yield AMARANTHUS tuberculatus Conyza CANADENSIS L. Cronq
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Predictive markers of endocrine response in breast cancer 被引量:2
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作者 Duniya Mosly Arran Turnbull +2 位作者 Andrew Sims Carol Ward Simon langdon 《World Journal of Experimental Medicine》 2018年第1期1-7,共7页
Ongoing clinical and research efforts seek to optimise the use of endocrine therapy in the treatment of breast cancer. Accurate biomarkers are needed that predict response for individual patients. The presence of the ... Ongoing clinical and research efforts seek to optimise the use of endocrine therapy in the treatment of breast cancer. Accurate biomarkers are needed that predict response for individual patients. The presence of the estrogen receptor(ER) as the direct(for tamoxifen and fulvestrant) or indirect(for aromatase inhibitors) target molecule for endocrine therapy remains the foremost biomarker and determinant of response. However, ER expression only poorly predicts outcome and further indicators of response or resistance are required. The development and application of molecular signature assays such as Oncotype Dx, Prosigna, Mammaprint and Endopredict have provided valuable information on prognosis and these are being used to support clinical decision making on whether endocrine therapy alone alongside surgery is sufficient for ER-positive early stage breast cancers or whether combination of endocrine with chemotherapy are also warranted. Ki67, the proliferation marker, has been widely used in the neo-adjuvant(pre-operative) setting to help predict response and long term outcome. Gene expression studies within the same setting have allowed monitoring of changes of potential predictive markers. These have identified frequent changes in estrogenregulated and proliferation genes. Specific molecules such as mutant ER may also prove helpful biomarkers in predicting outcome and monitoring response to treatment. 展开更多
关键词 ESTROGEN IL6ST BIOMARKER BREAST cancer PREDICTIVE
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Human epidermal growth factor receptor targeted inhibitors for the treatment of ovarian cancer 被引量:1
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作者 Maria Bonello ANDrew Harvey Sims Simon Peter langdon 《Cancer Biology & Medicine》 SCIE CAS CSCD 2018年第4期375-388,共14页
Ovarian cancer is the second most lethal gynecological cancer worldwide and while most patients respond to initial therapy, they often relapse with resistant disease. Human epidermal growth factor receptors(especially... Ovarian cancer is the second most lethal gynecological cancer worldwide and while most patients respond to initial therapy, they often relapse with resistant disease. Human epidermal growth factor receptors(especially HER1/EGFR and HER2/ERBB2) are involved in disease progression; hence, strategies to inhibit their action could prove advantageous in ovarian cancer patients,especially in patients resistant to first line therapy. Monoclonal antibodies and tyrosine kinase inhibitors are two classes of drugs that act on these receptors. They have demonstrated valuable antitumor activity in multiple cancers and their possible use in ovarian cancer continues to be studied. In this review, we discuss the human epidermal growth factor receptor family; review emerging clinical studies on monoclonal antibodies and tyrosine kinase inhibitors targeting these receptors in ovarian cancer patients; and propose future research possibilities in this area. 展开更多
关键词 TYROSINE kinase MONOCLONAL antibodies OVARIAN cancer INHIBITORS HER RECEPTORS
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Human IgG1 antibodies suppress angiogenesis in a target-independent manner
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作者 Sasha Bogdanovich Younghee Kim +33 位作者 Takeshi Mizutani Reo Yasuma Laura Tudisco Valeria Cicatiello Ana Bastos-Carvalho Nagaraj Kerur Yoshio Hirano Judit Z Baffi Valeria Tarallo Shengjian Li Tetsuhiro Yasuma Parthasarathy Arpitha Benjamin J Fowler Charles B Wright Ivana Apicella Adelaide Greco Arturo Brunetti Menotti Ruvo Annamaria Sandomenico Miho Nozaki Ryo Ijima Hiroki Kaneko Yuichiro Ogura Hiroko Terasaki Balamurali K Ambati Jeanette HW Leusen Wallace Y langdon Michael R Clark Kathryn L Armour Pierre Bruhns J Sjef Verbeek Bradley D Gelfand Sandro De Falco Jayakrishna Ambati 《Signal Transduction and Targeted Therapy》 SCIE 2016年第1期158-171,共14页
Aberrant angiogenesis is implicated in diseases affecting nearly 10%of the world’s population.The most widely used antiangiogenic drug is bevacizumab,a humanized IgG1 monoclonal antibody that targets human VEGFA.Alth... Aberrant angiogenesis is implicated in diseases affecting nearly 10%of the world’s population.The most widely used antiangiogenic drug is bevacizumab,a humanized IgG1 monoclonal antibody that targets human VEGFA.Although bevacizumab does not recognize mouse Vegfa,it inhibits angiogenesis in mice.Here we show bevacizumab suppressed angiogenesis in three mouse models not via Vegfa blockade but rather Fc-mediated signaling through FcγRI(CD64)and c-Cbl,impairing macrophage migration.Other approved humanized or human IgG1 antibodies without mouse targets(adalimumab,alemtuzumab,ofatumumab,omalizumab,palivizumab and tocilizumab),mouse IgG2a,and overexpression of human IgG1-Fc or mouse IgG2a-Fc,also inhibited angiogenesis in wild-type and FcγR humanized mice.This anti-angiogenic effect was abolished by Fcgr1 ablation or knockdown,Fc cleavage,IgG-Fc inhibition,disruption of Fc-FcγR interaction,or elimination of FcRγ-initated signaling.Furthermore,bevacizumab’s Fc region potentiated its anti-angiogenic activity in humanized VEGFA mice.Finally,mice deficient in FcγRI exhibited increased developmental and pathological angiogenesis.These findings reveal an unexpected anti-angiogenic function for FcγRI and a potentially concerning off-target effect of hIgG1 therapies. 展开更多
关键词 CD64 ANGIOGENESIS ANTIBODIES
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陶瓷超塑性综述
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作者 Yasuhiro Maehara Terence G langdon 黄企铭 《洛阳工学院学报》 1991年第1期79-90,共12页
现已公认超塑性是陶瓷中一种很有潜力的变形工艺.本文总结了陶瓷及其它非金属材料中超型性的主要特点并考察了这些材料中相变与组织两种超塑性的报导.结果表明其与金属既有相同又有不同之处.相同的是应变速率随应力及晶粒尺寸的变化,重... 现已公认超塑性是陶瓷中一种很有潜力的变形工艺.本文总结了陶瓷及其它非金属材料中超型性的主要特点并考察了这些材料中相变与组织两种超塑性的报导.结果表明其与金属既有相同又有不同之处.相同的是应变速率随应力及晶粒尺寸的变化,重要的区别是必须考虑到陶瓷中的晶间非晶相的作用.在金属间化合物及地质材料中超塑性同样也是重要的,在地质材料中无论在试验室试验或自然界的变形中部有超塑变形的迹象. 展开更多
关键词 陶瓷 超塑性 变形
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样品零件的快速制作
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作者 Ray langdon 陈家基 《轻型汽车技术》 1994年第2期28-32,57,共5页
这是一种最新的自动化工艺过程。这种过程不依赖传统的机床工具就筋把各种样件制作出来。采用RP工艺过程,只需几个工时就能把CAD所产生的3维模型转化为一个实物零件。
关键词 样品快速制作 汽车 CAD/CAM
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A High Frequency Boundary Element Method for Scattering by Convex Polygons with Impedance Boundary Conditions
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作者 S.N.Chandler-Wilde S.langdon M.Mokgolele 《Communications in Computational Physics》 SCIE 2012年第2期573-593,共21页
We consider scattering of a time harmonic incident plane wave by a convex polygon with piecewise constant impedance boundary conditions.Standard finite or boundary element methods require the number of degrees of free... We consider scattering of a time harmonic incident plane wave by a convex polygon with piecewise constant impedance boundary conditions.Standard finite or boundary element methods require the number of degrees of freedom to grow at least linearly with respect to the frequency of the incident wave in order to maintain accuracy.Extending earlier work by Chandler-Wilde and Langdon for the sound soft problem,we propose a novel Galerkin boundary element method,with the approximation space consisting of the products of plane waves with piecewise polynomials supported on a graded mesh with smaller elements closer to the corners of the polygon.Theoretical analysis and numerical results suggest that the number of degrees of freedom required to achieve a prescribed level of accuracy grows only logarithmically with respect to the frequency of the incident wave. 展开更多
关键词 Boundary integral equation method high frequency scattering convex polygons impedance boundary conditions
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Influence of Adjuvants on the Efficacy of Tolpyralate plus Atrazine for the Control of Annual Grass and Broadleaf Weeds in Corn with and without Roundup WeatherMAX<sup>&reg;</sup>
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作者 Nicole M. langdon Nader Soltani +3 位作者 Alan J. Raedar Darren E. Robinson David C. Hooker Peter H. Sikkema 《American Journal of Plant Sciences》 2020年第3期465-495,共31页
Tolpyralate is a new HPPD-inhibiting herbicide that is efficacious on annual grass and broadleaf weed species in corn. For maximum herbicide performance of tolpyralate, it is recommended that atrazine is tank mixed wi... Tolpyralate is a new HPPD-inhibiting herbicide that is efficacious on annual grass and broadleaf weed species in corn. For maximum herbicide performance of tolpyralate, it is recommended that atrazine is tank mixed with tolpyralate along with the adjuvants methylated seed oil concentrate (MSO) plus urea ammonia nitrate (UAN). A common use pattern of tolpyralate plus atrazine will be in a tank mix with Roundup WeatherMAX&reg;due to the high proportion of corn acres that are seeded to Roundup Ready&reg;hybrids in Eastern Canada. There is no information in the peer-reviewed literature if the adjuvant system in Roundup WeatherMAX&reg;is adequate for optimal herbicide performance of tolpyralate plus atrazine, or if MSO and UAN are still required. Six field trials were conducted over two years near Ridgetown and Exeter, ON, Canada to determine if adjuvants are still required when tolpyralate plus atrazine is tank mixed with Roundup WeatherMAX&reg;in corn. Tolpyralate plus atrazine plus MSO and Roundup WeatherMAX&reg;plus tolpyralate plus atrazine provided excellent control of velvetleaf, pigweed spp, common ragweed, lambsquarters, ladysthumb, wild mustard, flower-of-an-hour, barnyardgrass and green foxtail in this study. Results of this study show that in the absence of Roundup WeatherMAX&reg;, weed control with tolpyralate plus atrazine was improved substantially with the addition of MSO;however, there was little to no increase in weed control with the addition of UAN. When tolpyralate plus atrazine was co-applied with Roundup WeatherMAX&reg;, there was no improvement in weed control with the addition of MSO and/or UAN. 展开更多
关键词 Biomass Broadleaf Weeds CORN EFFICACY Grassweeds ROUNDUP WeatherMAX Methylated Seed Oil Urea Ammonia Nitrate Weed CONTROL Yield Zea mays L
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汽车工厂样品零件的快速制作
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作者 Ray langdon 陈家基 《轻型汽车技术》 1994年第3期18-19,17,共3页
本文所介绍这项新技术在汽车工业中的应用。主要介绍了英国罗孚汽车公司建立的立体制版实验室。该实验室对这项新技术作了很大改进,完全超越了试验阶段。该实验室制作了很多发动机样件,获得了丰硕的经济效益。
关键词 样品快速制作 汽车 CAD/CAM
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Tolpyralate + Atrazine Applied Preemergence Provides Residual GR Canada Fleabane [<i>Conyza canadensis</i>(L.) Cronq.] Control Similar to Current Industry Standards
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作者 Nicole M. langdon Nader Soltani +3 位作者 Alan J. Raedar David C. Hooker Darren E. Robinson Peter H. Sikkema 《Agricultural Sciences》 2020年第4期417-424,共8页
Tolpyralate is a benzoylpyrazole, 4-hydroxyphenyl-pyruvate dioxygenase inhibitor, and a herbicide registered for use in corn. The efficacy of tolpyralate plus atrazine to provide full-season residual control of glypho... Tolpyralate is a benzoylpyrazole, 4-hydroxyphenyl-pyruvate dioxygenase inhibitor, and a herbicide registered for use in corn. The efficacy of tolpyralate plus atrazine to provide full-season residual control of glyphosate-resistant (GR) Canada fleabane in corn is not known under Ontario environmental conditions. Five field trials were completed over a two-year period (2018-19) in south-western Ontario on farms with confirmed GR Canada fleabane [Conyza canadensis (L.) Cronq.] populations to determine if tolpyralate + atrazine provides full-season residual control of GR Canada fleabane in corn. Corn injury was less than 10% with all treatments. At 4 weeks after application (WAA), tolpyralate (30 g&middot;ai&middot;ha&minus;1), tolpyralate (40 g&middot;ai&middot;ha&minus;1), and atrazine (560 g&middot;ai&middot;ha&minus;1) controlled GR Canada fleabane 64, 78 and 72%, respectively. A tank mix of tolpyralate + atrazine at both rates improved GR Canada fleabane control to 94%. Saflufenacil/dimethenamid-p, mesotrione + atrazine, and dicamba/atrazine controlled GR Canada fleabane 99, 95 and 92%, respectively. At 8 WAA, tolpyralate (30 g&middot;ai&middot;ha&minus;1), tolpyralate (40 g&middot;ai&middot;ha&minus;1) and atrazine (560 g&middot;ai&middot;ha&minus;1) controlled GR Canada fleabane 83, 88, and 83%, respectively (Table 2). The tank mixes of tolpyralate (30 g&middot;ai&middot;ha&minus;1) + atrazine (560 g&middot;ai&middot;ha&minus;1) and tolpyralate (40 g&middot;ai&middot;ha&minus;1) + atrazine (560 g&middot;ai&middot;ha&minus;1) controlled GR Canada fleabane 94, and 97%, respectively, 8 WAA which was similar to saflufenacil/dimethenamid-p, mesotrione + atrazine and dicamba/atrazine. There was no treatment difference for corn yield. Based on these results, tolpyralate (40 g&middot;ha&minus;1), tolpyralate (30 g&middot;ha&minus;1) + atrazine and tolpyralate (40 g&middot;ha&minus;1) + atrazine, applied PRE, provided similar control of GR Canada fleabane as current industry standards at 8 WAA. 展开更多
关键词 Crop Injury Density Efficacy GLYPHOSATE-RESISTANT Horseweed Marestail RESIDUAL WEED CONTROL Sensitivity WEED CONTROL g·ai·ha-1
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Dopaminergic system does not play a major role in the precipitated cannabinoid withdrawal syndrome
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作者 M Clara SANUDO-PENA Michelle FORCE +3 位作者 TSOU Kang Gabrielle McLEMORE langdon ROBERTS J Michael WALKER 《中国药理学报》 CSCD 1999年第12期1121-1124,共4页
AIM:To determine the dopaminergic system involvement in precipitated cannabinoid withdrawal syndrome.METHODS:The dopamine D_(1)receptor antagonist SCH23390 or the dopamine D_(2)receptor antagonist sulphide was adminis... AIM:To determine the dopaminergic system involvement in precipitated cannabinoid withdrawal syndrome.METHODS:The dopamine D_(1)receptor antagonist SCH23390 or the dopamine D_(2)receptor antagonist sulphide was administered to rats chronically treated with either△^(9)-tetrahydrocannabinol(THC)or vehicle.Subjects were then injected with either SR141716A or vehicle and behavior was observed for 1 h.RESULTS:Administration of the cannabinoid receptor antagonist SR141716A to animals chronically treated with THC as described by Tsou et al(1995)produced a profound withdrawal syndrome.Treatment with dopamine antagonists did not attenuate cannabinoid precipitated withdrawal syndrome in THC tolerant animals while the agonists increased the syndrome.CONCLUSION:It is unlikely that the dopaminergic system plays a major role in mediating the behavioral aspects of the cannabinoid withdrawal syndrome. 展开更多
关键词 CANNABINOIDS TETRAHYDROCANNABINOL SR141716A substance withdrawal syndrome dopamine D_(1)receptors dopamine D_(2)receptors dopamine antagonists PRURITUS PAIN
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Human blastomere rotation in early cleavage embryos is not associated with reduced implantation: Evidence from time-lapse videography
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作者 Emma P langdon Yan-he Liu +1 位作者 Phillip L Matson Peter J Mark 《Asian pacific Journal of Reproduction》 2019年第6期297-298,共2页
Dear Editor,Time-lapse videography of human embryos allows for the easy visualization of the embryos without removing them from the protective environment of the incubator[1],the measurement of various morphokinetic(q... Dear Editor,Time-lapse videography of human embryos allows for the easy visualization of the embryos without removing them from the protective environment of the incubator[1],the measurement of various morphokinetic(quantitative)parameters[2],and the identification of abnormalities of growth(qualitative parameters)such as direct cleavage[3],reverse cleavage[4]and intercellular contact of blastomeres[5]. 展开更多
关键词 HUMAN embryos BLASTOMERE ROTATION TIME-LAPSE videography
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球状颗粒强化复合材料Al-6061/Al_2O_3的强化作用 被引量:7
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作者 王经涛 古川稔 +2 位作者 堀田善治 根本实 T.G.langdon 《复合材料学报》 EI CAS CSCD 北大核心 2001年第3期52-55,共4页
研究了 6 0 6 1/ Al2 O3复合材料中球形 Al2 O3颗粒的强化作用。该强化颗粒的加入大大提高了材料在固溶处理后未时效状态的强度。对组织的观察和位错密度的测量表明 ,该强化作用与位错强化模型的计算结果一致。强化颗粒的加入还显著提... 研究了 6 0 6 1/ Al2 O3复合材料中球形 Al2 O3颗粒的强化作用。该强化颗粒的加入大大提高了材料在固溶处理后未时效状态的强度。对组织的观察和位错密度的测量表明 ,该强化作用与位错强化模型的计算结果一致。强化颗粒的加入还显著提高了材料在各种时效状态的加工硬化率。将 Ashby提出的含异质颗粒复合材料的几何必须位错模型与位错强化模型结合 。 展开更多
关键词 金属基复合材料 球状强化颗粒 位错强化 加工硬化 Al-6061/Al2O3 氧化铝 铝基复合材料
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Recent advances using equal-channel angular pressing to improve the properties of biodegradable Mg-Zn alloys 被引量:2
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作者 Mohammad Hashemi Reza Alizadeh Terence G.langdon 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第7期2260-2284,共25页
Magnesium alloys are of considerable current interest for use as degradable implants due to their unique properties including biodegrad-ability,biocompatibility,low density and adequate mechanical properties.Neverthel... Magnesium alloys are of considerable current interest for use as degradable implants due to their unique properties including biodegrad-ability,biocompatibility,low density and adequate mechanical properties.Nevertheless,there is a need to further improve these properties either by alloying or through the use of appropriate processing.Among the different biodegradable Mg alloys now in use,the Mg-Zn series are of special interest and have been the subject of many research investigations.This is primarily because Zn is an essential element for the human body in addition to its positive effects in improving the mechanical strength and lowering the degradation rate of the implant.The properties of Mg-Zn alloys may be further improved both through the addition of third and fourth alloying elements such as Ca,Ag,Sn or Sr and/or by thermo-mechanical processing where the latter is more environmentally and economically favorable.In practice,procedures based on the application of severe plastic deformation(SPD)are especially suited to produce fine-grained microstructures with improved mechanical,degradation and cell behavior.Equal-channel angular pressing(ECAP)is a popular SPD technique that has the capability of pro-ducing bulk materials that are sufficiently large for use as typical implants.Accordingly,this review is designed to provide a comprehensive summary of the research that has been undertaken on ECAP-processed biodegradable Mg-Zn alloys. 展开更多
关键词 Bio-degradation ECAP Fine-grained microstructure Mg–Zn alloys Severe plastic deformation
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相比例对高压扭转Ti-6Al-4V合金晶粒细化及显微硬度的影响 被引量:6
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作者 张文井 付杰 +2 位作者 黄毅 丁桦 Terence G.langdon 《材料与冶金学报》 CAS 北大核心 2015年第4期298-304,共7页
冷轧态Ti-6Al-4V(TC4)合金经两种不同热处理制度处理之后,分别得到70%的等轴α相和30%的α+β片层组织(TC4-1)与25%的等轴α相和75%的α+β片层组织(TC4-2).等轴α相的晶粒尺寸分别为7.0±2μm和9.5±1.5μm.在室温下进行高压扭... 冷轧态Ti-6Al-4V(TC4)合金经两种不同热处理制度处理之后,分别得到70%的等轴α相和30%的α+β片层组织(TC4-1)与25%的等轴α相和75%的α+β片层组织(TC4-2).等轴α相的晶粒尺寸分别为7.0±2μm和9.5±1.5μm.在室温下进行高压扭转,扭转过程中施加6.0 GPa的压力,扭转速度为1 r/min,分别扭转了1/4、5、10和20圈.随着扭转圈数和片层组织的增加,组织更为均匀.经20圈扭转变形后,TC4-1和TC4-2中的晶粒尺寸分别为115±30 nm和75±15 nm.随着片层组织的增加,显微硬度值显著升高.同时探讨了相比例对晶粒细化机制的影响. 展开更多
关键词 TI-6AL-4V合金 高压扭转 相比例 晶粒细化
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The thermal instability mechanism and annealed deformation behavior of Cu/Nb nanolaminate composites
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作者 Chaogang Ding Jie Xu +2 位作者 Debin Shan Bin Guo Terence G.langdon 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2023年第26期163-173,共11页
Nanoscale metallic multilayers(NMMs)have attracted significant attention owing to their enhanced me-chanical properties and excellent thermal stability.However,the underlying deformation mechanisms of the high-tempera... Nanoscale metallic multilayers(NMMs)have attracted significant attention owing to their enhanced me-chanical properties and excellent thermal stability.However,the underlying deformation mechanisms of the high-temperature annealed microstructures have not been well clarified.In this study,the effect of annealing temperatures(500,600,700,800,and 1000℃)on the microstructural evolution and mechan-ical properties of Cu/Nb NMMs was investigated systematically.The results show that when the anneal-ing temperature is lower than 800℃the Cu/Nb NMMs maintain their initial continuous nanolayered structure.As the annealing temperature reaches 1000℃,a thermal instability,driven by thermal grain boundary grooving and a Rayleigh instability,leads to the pinching offof the nanolayered structure and even a complete disintegration into an equiaxed grain structure.Uniaxial tensile tests show that 1000℃annealed samples exhibit an enhanced strain hardening capability compared to as-rolled NMMs and this imparts superior ultimate tensile strength(∼492 MPa)and a high elongation(∼20%).TEM observations demonstrate that high-density entangled dislocations exist in the Cu-Nb interface and layers after tensile testing of the high-temperature annealed samples.The dislocation tangles lead to stable and progres-sive strain hardening which is the dominant factor in determining the superior combination of strength and ductility of the high-temperature annealed samples.Thus,this study offers a promising strategy for evading the strength-ductility dilemma and instead promotes a more in-depth understanding of the de-formation mechanisms of heterostructured materials. 展开更多
关键词 ANNEALING INTERFACES Mechanical properties Nanoscale metallic multilayers Thermal stability
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