Copper-based azide(Cu(N_(3))2 or CuN_(3),CA)chips synthesized by in-situ azide reaction and utilized in miniaturized explosive systems has become a hot research topic in recent years.However,the advantages of in-situ ...Copper-based azide(Cu(N_(3))2 or CuN_(3),CA)chips synthesized by in-situ azide reaction and utilized in miniaturized explosive systems has become a hot research topic in recent years.However,the advantages of in-situ synthesis method,including small size and low dosage,bring about difficulties in quantitative analysis and differences in ignition capabilities of CA chips.The aim of present work is to develop a simplified quantitative analysis method for accurate and safe analysis of components in CA chips to evaluate and investigate the corresponding ignition ability.In this work,Cu(N_(3))2 and CuN_(3)components in CA chips were separated through dissolution and distillation by utilizing the difference in solubility and corresponding content was obtained by measuring N_(3)-concentration through spectrophotometry.The spectrophotometry method was optimized by studying influencing factors and the recovery rate of different separation methods was studied,ensuring the accuracy and reproducibility of test results.The optimized method is linear in range from 1.0-25.0 mg/L,with a correlation coefficient R^(2)=0.9998,which meets the requirements of CA chips with a milligram-level content test.Compared with the existing ICP method,component analysis results of CA chips obtained by spectrophotometry are closer to real component content in samples and have satisfactory accuracy.Moreover,as its application in miniaturized explosive systems,the ignition ability of CA chips with different component contents for direct ink writing CL-20 and the corresponding mechanism was studied.This study provided a basis and idea for the design and performance evaluation of CA chips in miniaturized explosive systems.展开更多
目的:分析骨髓增殖性肿瘤(MPN)患者不确定潜能的克隆性造血(CHIP)相关基因突变谱和临床特征,探讨CHIP相关基因与其心脑血管事件(CCE)的相关性及可能作用机制。方法:回顾性分析2019年8月-2022年7月首都医科大学附属北京安贞医院血液科收...目的:分析骨髓增殖性肿瘤(MPN)患者不确定潜能的克隆性造血(CHIP)相关基因突变谱和临床特征,探讨CHIP相关基因与其心脑血管事件(CCE)的相关性及可能作用机制。方法:回顾性分析2019年8月-2022年7月首都医科大学附属北京安贞医院血液科收治的73例MPN患者的临床资料和二代测序结果,采用Logistic回归分析CHIP相关基因、炎症细胞因子对MPN患者CCE的影响。结果:55例(75.3%)MPN患者检出CHIP相关基因,原发性血小板增多症(ET)和真性红细胞增多症(PV)患者CHIP相关基因各突变频率差异无统计学意义。CHIP相关基因突变以单基因形式为主,检出率从高至低依次为JAK2V617F(63.0%,46/73)、ASXL1(16.4%,12/73)、TET2(11.0%,8/73)、DNMT3A(9.6%,7/73)、SRSF2(6.9%,5/73)、SF3B1(4.1%,3/73)、TP53(1.4%,1/73)和PPMID(1.4%,1/73)。年龄>60岁患者CHIP相关基因检出率明显高于≤60岁者[91.7%(33/36)vs 59.5%(22/37)]。27例(37.0%)MPN患者伴CCE(MPN/CCE),2次CCE者5例,均为动脉事件。CCE组患者年龄(62.8±12.8 vs 53.9±15.8岁,P=0.015)、IL-1β水平(17.7±26.0vs 4.3±8.6,P=0.012)、IL-8水平(360.7±598.6 vs 108.3±317.0,P=0.045)、血栓形成史(29.6%vs 2.2%,P=0.020)和CHIP相关基因检出率(88.9%vs 67.4%,P=0.040)高于无CCE组。多因素Logistic回归分析结果显示,年龄(OR=0.917,95%CI:0.843-0.999,P=0.047)、血栓形成史(OR=34.148,95%CI:2.392-487.535,P=0.009)、任何1个CHIP相关基因突变(OR=16.065,95%CI:1.217-212.024,P=0.035)和IL-1β水平升高(OR=0.929,95%CI:0.870-0.992,P=0.027)均是MPN/CCE的独立危险因素;CHIP相关单基因突变与MPN/CCE无关,但DNMT3A(OR=88.717,95%CI:2.690-292.482,P=0.012)、ASXL1(OR=7.941,95%CI:1.045-60.353,P=0.045)突变是PV/CCE的独立危险因素。结论:MPN患者CHIP相关基因突变率高,尤其是60岁以上患者;高龄、血栓形成史、CHIP相关基因突变和IL-1β水平升高是MPN发生CCE的独立危险因素。DNMT3A、ASXL1单基因突变是PV患者CCE的独立危险因素。CHIP相关基因突变及炎症细胞因子IL-1β升高是MPN新的CCE危险因素。展开更多
Diabetes mellitus is a global health problem resulting from islet dysfunction or insulin resistance.The mechanisms of islet dysfunction are still under investigation.Islet hormone secretion is the main function of isl...Diabetes mellitus is a global health problem resulting from islet dysfunction or insulin resistance.The mechanisms of islet dysfunction are still under investigation.Islet hormone secretion is the main function of islets,and serves an important role in the homeostasis of blood glucose.Elucidating the detailed mechanism of islet hormone secretome distortion can provide clues for the treatment of diabetes.Therefore,it is crucial to develop accurate,real-time,laborsaving,high-throughput,automated,and cost-effective techniques for the sensing of islet secretome.Microfluidic chips,an elegant platform that combines biology,engineering,computer science,and biomaterials,have attracted tremendous interest from scientists in the field of diabetes worldwide.These tiny devices are miniatures of traditional experimental systems with more advantages of timesaving,reagent-minimization,automation,high-throughput,and online detection.These features of microfluidic chips meet the demands of islet secretome analysis and a variety of chips have been designed in the past 20 years.In this review,we present a brief introduction of microfluidic chips,and three microfluidic chipsbased islet hormone sensing techniques.We focus mainly on the theory of these techniques,and provide detailed examples based on these theories with the hope of providing some insights into the design of future chips or whole detection systems.展开更多
On-demand droplet sorting is extensively applied for the efficient manipulation and genome-wide analysis of individual cells.However,state-of-the-art microfluidic chips for droplet sorting still suffer from low sortin...On-demand droplet sorting is extensively applied for the efficient manipulation and genome-wide analysis of individual cells.However,state-of-the-art microfluidic chips for droplet sorting still suffer from low sorting speeds,sample loss,and labor-intensive preparation procedures.Here,we demonstrate the development of a novel microfluidic chip that integrates droplet generation,on-demand electrostatic droplet charging,and high-throughput sorting.The charging electrode is a copper wire buried above the nozzle of the microchannel,and the deflecting electrode is the phosphate buffered saline in the microchannel,which greatly simplifies the structure and fabrication process of the chip.Moreover,this chip is capable of high-frequency droplet generation and sorting,with a frequency of 11.757 kHz in the drop state.The chip completes the selective charging process via electrostatic induction during droplet generation.On-demand charged microdroplets can arbitrarilymove to specific exit channels in a three-dimensional(3D)-deflected electric field,which can be controlled according to user requirements,and the flux of droplet deflection is thereby significantly enhanced.Furthermore,a lossless modification strategy is presented to improve the accuracy of droplet deflection or harvest rate from 97.49% to 99.38% by monitoring the frequency of droplet generation in real time and feeding it back to the charging signal.This chip has great potential for quantitative processing and analysis of single cells for elucidating cell-to-cell variations.展开更多
趋化抑制蛋白(Chemotaxis Inhibitory Protein ofStaphylococcus aureus,CHIPS)是由金黄色葡萄球菌分泌到菌体外的一种蛋白。在感染早期,它能特异性地与中性粒细胞和单核细胞上的C5a受体(C5aR)和fMLP受体(FPR)结合,从而阻止中性粒细胞...趋化抑制蛋白(Chemotaxis Inhibitory Protein ofStaphylococcus aureus,CHIPS)是由金黄色葡萄球菌分泌到菌体外的一种蛋白。在感染早期,它能特异性地与中性粒细胞和单核细胞上的C5a受体(C5aR)和fMLP受体(FPR)结合,从而阻止中性粒细胞和单核细胞对C5a和fMLP的结合作用,导致对病原吞噬作用的延迟。人们可以利用CHIPS对C5a-C5aR的阻止作用来研制治疗由C5a诱发的炎症性疾病的药物。将CHIPS作为免疫原防治疾病也将成为新的研究课题。实验成功构建了CHIPS蛋白的原核表达系统,为CHIPS免疫原性研究及蛋白的其他功能研究奠定了基础。展开更多
Based on the mechanism of chip breaking and the principle of semi-solid thixomolding, the lathe process of AZ91D magnesium alloys chips used in semi-solid thixotropic injection molding process was studied. With three ...Based on the mechanism of chip breaking and the principle of semi-solid thixomolding, the lathe process of AZ91D magnesium alloys chips used in semi-solid thixotropic injection molding process was studied. With three kinds of turning tools, such as 31303C5, 31003C and 31303C, different chips were gotten. And by one tool with different lathe parameters, different chips were gotten. The results show that, under the needed condition of the thixotropic injection molding machine, the ideal chips are gotten and the size of magnesium alloy chips must be about 35mm, and the turning tool is chosen, whose chip breaker groove is narrower and the depth of cutting is more than 3mm as well as the amount of feed is larger than 0.3mm. The deformation occurs on the microstructure of the chips, and the residual stress is important to the later microstructure of semi-solid state in injection molding.展开更多
The present paper is related to the conversion of Ti–6Al–4V chips into powder and investigates the usability of the produced powder in powder metallurgy applications. In this regard, a disc-milling process was appli...The present paper is related to the conversion of Ti–6Al–4V chips into powder and investigates the usability of the produced powder in powder metallurgy applications. In this regard, a disc-milling process was applied to Ti–6Al–4V chips and the obtained powder was subsequently compacted. The compacted samples were sintered by the sinter hot isostatic pressing (sinter-HIP) method at 1200°C under high vacuum, their mechanical properties and microstructure were investigated and compared with those of commercial powder compacts subjected to the same preparation processes. The results showed that the produced powder exhibits greater flowability and higher apparent density than the commercial powder. However, the sintered products prepared from the commercial powder exhibited a higher relative density, lower porosity, and, as a result, greater flexural strength compared with the sintered compacts prepared from the produced powder. In addition, transgranular fracture was greater in the sintered products of the commercial powder. The microstructural studies revealed that the sintered products made from both the commercial and the produced powders consisted of α- and β-phase but contained more α-phase. All of the examined properties were found to be substantially affected by the particle size of the powders.展开更多
In this study, the processing and mechanical properties of porous metal matrix composites(MMCs) composed of spheroidal cast iron chips(GGG40) and bronze chips(CuSn10) and formed by hot isostatic pressing were investig...In this study, the processing and mechanical properties of porous metal matrix composites(MMCs) composed of spheroidal cast iron chips(GGG40) and bronze chips(CuSn10) and formed by hot isostatic pressing were investigated. Bronze chips(CuSn10) were used as a matrix component, and spheroidal cast iron(GGG40) chips were used as a reinforcement component. The MMCs were produced with different CuSn10 contents(90 wt%, 80 wt%, 70 wt%, and 60 wt%). The hot isostatic pressing process was performed under three different pressures and temperatures. The produced MMCs were characterized using density tests, Brinell hardness tests, and compression tests. In addition, the consolidation mechanism was investigated by X-ray diffraction(XRD) analysis and scanning electron microscopy. The test results were compared with those for bulk CuSn10 and bulk GGG40. Mechanical tests results revealed that the metallic chips can be recycled by using hot pressing and that the mechanical properties of the produced MMCs were similar to those of bulk CuSn10. XRD and microscopy studies showed that no intermetallic compounds formed between the metallic chips. The results showed that the CuSn10 and GGG40 chips were consolidated by mechanical interlocking.展开更多
The microstructural evolution of A356 machining chips in the semisolid state was studied at different temperatures and holding times. The results showed that the elongated α-Al grains first recrystallized in the semi...The microstructural evolution of A356 machining chips in the semisolid state was studied at different temperatures and holding times. The results showed that the elongated α-Al grains first recrystallized in the semisolid state and then became globular with a high shape factor(SF). Both the temperature and the holding time clearly affected the grain size and SF. When the heating temperature or holding time was increased, the grain size and SF gradually increased and finally became stable. Moreover, the Vickers hardness of primary α-Al grains gradually decreased with increasing heating temperature. The optimal slurry for semisolid processing, with a good combination of grain size and SF, was obtained when the chips were held at 600℃ for 15 min. The semisolid slurry of A356 chips exhibited a lower coarsening rate of α-Al grains than those produced by most of the conventional semisolid processes. The coarsening coefficient was determined to be 436 μm^3·s^(-1) on the basis of the linear Lifshitz–Slyozov–Wagner(LSW) relationship.展开更多
Objective:To evaluate the hazardous effects of fried potato chips upon the retina of two developmental stages of the albino rats aged 7 and 14 days from parturition.Methods:Pregnant rats were arranged into two groups:...Objective:To evaluate the hazardous effects of fried potato chips upon the retina of two developmental stages of the albino rats aged 7 and 14 days from parturition.Methods:Pregnant rats were arranged into two groups:control pregnant rats and consequently their delivered newborns until reaching 7 and 14 days old from parturition and fried potato chips group in which pregnant rats at the 6th day of gestation maintained on diet formed of fried potato chips supplied from the market mixed with standard diet at a concentration of 50%per each till 7 and 14 postpartum.Three fold integrated approaches were adopted,namely,histological,ultrastructural and proteomic analysis.Results:Histological examination of the retina of the experimental offsprings revealed many histopathological changes,including massive degeneration,vacuolization and cell loss in the ganglion cell layer,as well as general reduction in retinal size.At the ultrastructural level,the retina of experimental offsprings exhibited number of deformities,including ill differentiated and degenerated nuclear layer,malformed and vacuolated pigment epithelium with vesiculated and fragmented rough endoplasmic reticulum,degenerated outer segment of photoreceptors,as well as swollen choriocapillaris and loss of neuronal cells.Proteomic analysis of retina of the two experimental developmental stages showed variations in the expressed proteins as a result of intoxication which illustrated the adverse toxic effects of fried potato chips upon the retina.Conclusions:It can be concluded that the effect of fried potato chips on the development of retina in rats may be due to the presence of acrylamide or its metabolite.展开更多
Endothelial cells arranged on the vessel lumen are constantly stimulated by blood flow,blood pressure and pressureinduced cyclic stretch.These stimuli are sensed through mechanical sensory structures and converted int...Endothelial cells arranged on the vessel lumen are constantly stimulated by blood flow,blood pressure and pressureinduced cyclic stretch.These stimuli are sensed through mechanical sensory structures and converted into a series of functional responses through mechanotransduction pathways.The process will eventually affect vascular health.Therefore,there has been an urgent need to establish in vitro endothelial biomechanics and mechanobiology of models,which reproduce three-dimensional structure vascular system.In recent years,the rapid development in microfluidic technology makes it possible to replicate the key structural and functionally biomechanical characteristics of vessels.Here,we summarized the progress of microfluidic chips used for the investigation of endothelial biomechanics and mechanobiology of the vascular system.Firstly,we elucidated the contribution of shear stress and circumferential stress,to vascular physiology.Then,we reviewed some applications using microfluidic technology in angiogenesis and vasculogenesis,endothelial permeability and mechanotransduction,as well as the blood-brain barrier under these physical forces.Finally,we discussed the future obstacles in terms of the development and application of microfluidic vascular chips.展开更多
AZ91D magnesium alloy chips were adopted to prepare semi-solid billets.The chips were subjected to a series ofisothermal treatments for various holding times at 783?843 K after being compressed into billet at 523 K.Th...AZ91D magnesium alloy chips were adopted to prepare semi-solid billets.The chips were subjected to a series ofisothermal treatments for various holding times at 783?843 K after being compressed into billet at 523 K.The semi-solid microstructure of AZ91D magnesium alloy containing spherical solid particles was studied.The effects of reheating temperature and holding time on microstructures were investigated.And the semi-solid forming mechanism was discussed.The result shows that semi-solid billets with highly spheroidal and homogeneous grains can be prepared from chips by strain induced melt activation(SIMA) method.Meanwhile,it is found that increasing the heating temperature can accelerate the spheroidizing process and reduce the solid volume fraction.With the increase of the holding time,the solid particles become more globular,the grains grow slowly and the solid volume fraction slightly changes.At the same time,owing to the decrease ofinterfacial energy,the intragranular liquid phases form by the diffusion of solute atoms,the grain boundaries melt and grains separate from each other during the isothermal treatment.The grains gradually spheroidize and begin to merge with a further increase of the holding time.It is considered that the semi-solid forming process includes three stages:the recrystallization and the growth of grain stage,the semi-solid microstructure forming stage controlled by the diffusion of solute,and the spheroidization of solid particle stage controlled by the liquid-solid interface tension.展开更多
基金the financial support provided by the National Natural Science Foundation of China(Grant No.11872013).
文摘Copper-based azide(Cu(N_(3))2 or CuN_(3),CA)chips synthesized by in-situ azide reaction and utilized in miniaturized explosive systems has become a hot research topic in recent years.However,the advantages of in-situ synthesis method,including small size and low dosage,bring about difficulties in quantitative analysis and differences in ignition capabilities of CA chips.The aim of present work is to develop a simplified quantitative analysis method for accurate and safe analysis of components in CA chips to evaluate and investigate the corresponding ignition ability.In this work,Cu(N_(3))2 and CuN_(3)components in CA chips were separated through dissolution and distillation by utilizing the difference in solubility and corresponding content was obtained by measuring N_(3)-concentration through spectrophotometry.The spectrophotometry method was optimized by studying influencing factors and the recovery rate of different separation methods was studied,ensuring the accuracy and reproducibility of test results.The optimized method is linear in range from 1.0-25.0 mg/L,with a correlation coefficient R^(2)=0.9998,which meets the requirements of CA chips with a milligram-level content test.Compared with the existing ICP method,component analysis results of CA chips obtained by spectrophotometry are closer to real component content in samples and have satisfactory accuracy.Moreover,as its application in miniaturized explosive systems,the ignition ability of CA chips with different component contents for direct ink writing CL-20 and the corresponding mechanism was studied.This study provided a basis and idea for the design and performance evaluation of CA chips in miniaturized explosive systems.
文摘目的:分析骨髓增殖性肿瘤(MPN)患者不确定潜能的克隆性造血(CHIP)相关基因突变谱和临床特征,探讨CHIP相关基因与其心脑血管事件(CCE)的相关性及可能作用机制。方法:回顾性分析2019年8月-2022年7月首都医科大学附属北京安贞医院血液科收治的73例MPN患者的临床资料和二代测序结果,采用Logistic回归分析CHIP相关基因、炎症细胞因子对MPN患者CCE的影响。结果:55例(75.3%)MPN患者检出CHIP相关基因,原发性血小板增多症(ET)和真性红细胞增多症(PV)患者CHIP相关基因各突变频率差异无统计学意义。CHIP相关基因突变以单基因形式为主,检出率从高至低依次为JAK2V617F(63.0%,46/73)、ASXL1(16.4%,12/73)、TET2(11.0%,8/73)、DNMT3A(9.6%,7/73)、SRSF2(6.9%,5/73)、SF3B1(4.1%,3/73)、TP53(1.4%,1/73)和PPMID(1.4%,1/73)。年龄>60岁患者CHIP相关基因检出率明显高于≤60岁者[91.7%(33/36)vs 59.5%(22/37)]。27例(37.0%)MPN患者伴CCE(MPN/CCE),2次CCE者5例,均为动脉事件。CCE组患者年龄(62.8±12.8 vs 53.9±15.8岁,P=0.015)、IL-1β水平(17.7±26.0vs 4.3±8.6,P=0.012)、IL-8水平(360.7±598.6 vs 108.3±317.0,P=0.045)、血栓形成史(29.6%vs 2.2%,P=0.020)和CHIP相关基因检出率(88.9%vs 67.4%,P=0.040)高于无CCE组。多因素Logistic回归分析结果显示,年龄(OR=0.917,95%CI:0.843-0.999,P=0.047)、血栓形成史(OR=34.148,95%CI:2.392-487.535,P=0.009)、任何1个CHIP相关基因突变(OR=16.065,95%CI:1.217-212.024,P=0.035)和IL-1β水平升高(OR=0.929,95%CI:0.870-0.992,P=0.027)均是MPN/CCE的独立危险因素;CHIP相关单基因突变与MPN/CCE无关,但DNMT3A(OR=88.717,95%CI:2.690-292.482,P=0.012)、ASXL1(OR=7.941,95%CI:1.045-60.353,P=0.045)突变是PV/CCE的独立危险因素。结论:MPN患者CHIP相关基因突变率高,尤其是60岁以上患者;高龄、血栓形成史、CHIP相关基因突变和IL-1β水平升高是MPN发生CCE的独立危险因素。DNMT3A、ASXL1单基因突变是PV患者CCE的独立危险因素。CHIP相关基因突变及炎症细胞因子IL-1β升高是MPN新的CCE危险因素。
基金Supported by the Project of Suzhou Hospital of Anhui Medical University,No.2020A1Natural Science Project of North Anhui Health Vocational College,No.WZK201907.
文摘Diabetes mellitus is a global health problem resulting from islet dysfunction or insulin resistance.The mechanisms of islet dysfunction are still under investigation.Islet hormone secretion is the main function of islets,and serves an important role in the homeostasis of blood glucose.Elucidating the detailed mechanism of islet hormone secretome distortion can provide clues for the treatment of diabetes.Therefore,it is crucial to develop accurate,real-time,laborsaving,high-throughput,automated,and cost-effective techniques for the sensing of islet secretome.Microfluidic chips,an elegant platform that combines biology,engineering,computer science,and biomaterials,have attracted tremendous interest from scientists in the field of diabetes worldwide.These tiny devices are miniatures of traditional experimental systems with more advantages of timesaving,reagent-minimization,automation,high-throughput,and online detection.These features of microfluidic chips meet the demands of islet secretome analysis and a variety of chips have been designed in the past 20 years.In this review,we present a brief introduction of microfluidic chips,and three microfluidic chipsbased islet hormone sensing techniques.We focus mainly on the theory of these techniques,and provide detailed examples based on these theories with the hope of providing some insights into the design of future chips or whole detection systems.
基金The authors acknowledge the financial support from the NationalNatural Science Foundation ofChina(No.52275562)the Technology Innovation Fund of Huazhong University of Science and Technology(No.2022JYCXJJ015).
文摘On-demand droplet sorting is extensively applied for the efficient manipulation and genome-wide analysis of individual cells.However,state-of-the-art microfluidic chips for droplet sorting still suffer from low sorting speeds,sample loss,and labor-intensive preparation procedures.Here,we demonstrate the development of a novel microfluidic chip that integrates droplet generation,on-demand electrostatic droplet charging,and high-throughput sorting.The charging electrode is a copper wire buried above the nozzle of the microchannel,and the deflecting electrode is the phosphate buffered saline in the microchannel,which greatly simplifies the structure and fabrication process of the chip.Moreover,this chip is capable of high-frequency droplet generation and sorting,with a frequency of 11.757 kHz in the drop state.The chip completes the selective charging process via electrostatic induction during droplet generation.On-demand charged microdroplets can arbitrarilymove to specific exit channels in a three-dimensional(3D)-deflected electric field,which can be controlled according to user requirements,and the flux of droplet deflection is thereby significantly enhanced.Furthermore,a lossless modification strategy is presented to improve the accuracy of droplet deflection or harvest rate from 97.49% to 99.38% by monitoring the frequency of droplet generation in real time and feeding it back to the charging signal.This chip has great potential for quantitative processing and analysis of single cells for elucidating cell-to-cell variations.
文摘趋化抑制蛋白(Chemotaxis Inhibitory Protein ofStaphylococcus aureus,CHIPS)是由金黄色葡萄球菌分泌到菌体外的一种蛋白。在感染早期,它能特异性地与中性粒细胞和单核细胞上的C5a受体(C5aR)和fMLP受体(FPR)结合,从而阻止中性粒细胞和单核细胞对C5a和fMLP的结合作用,导致对病原吞噬作用的延迟。人们可以利用CHIPS对C5a-C5aR的阻止作用来研制治疗由C5a诱发的炎症性疾病的药物。将CHIPS作为免疫原防治疾病也将成为新的研究课题。实验成功构建了CHIPS蛋白的原核表达系统,为CHIPS免疫原性研究及蛋白的其他功能研究奠定了基础。
文摘Based on the mechanism of chip breaking and the principle of semi-solid thixomolding, the lathe process of AZ91D magnesium alloys chips used in semi-solid thixotropic injection molding process was studied. With three kinds of turning tools, such as 31303C5, 31003C and 31303C, different chips were gotten. And by one tool with different lathe parameters, different chips were gotten. The results show that, under the needed condition of the thixotropic injection molding machine, the ideal chips are gotten and the size of magnesium alloy chips must be about 35mm, and the turning tool is chosen, whose chip breaker groove is narrower and the depth of cutting is more than 3mm as well as the amount of feed is larger than 0.3mm. The deformation occurs on the microstructure of the chips, and the residual stress is important to the later microstructure of semi-solid state in injection molding.
基金financially supported by Faculty Member Training Program funded by Council of Higher Education Turkey [OYP-05276-DR-12]
文摘The present paper is related to the conversion of Ti–6Al–4V chips into powder and investigates the usability of the produced powder in powder metallurgy applications. In this regard, a disc-milling process was applied to Ti–6Al–4V chips and the obtained powder was subsequently compacted. The compacted samples were sintered by the sinter hot isostatic pressing (sinter-HIP) method at 1200°C under high vacuum, their mechanical properties and microstructure were investigated and compared with those of commercial powder compacts subjected to the same preparation processes. The results showed that the produced powder exhibits greater flowability and higher apparent density than the commercial powder. However, the sintered products prepared from the commercial powder exhibited a higher relative density, lower porosity, and, as a result, greater flexural strength compared with the sintered compacts prepared from the produced powder. In addition, transgranular fracture was greater in the sintered products of the commercial powder. The microstructural studies revealed that the sintered products made from both the commercial and the produced powders consisted of α- and β-phase but contained more α-phase. All of the examined properties were found to be substantially affected by the particle size of the powders.
基金financially supported by the Scientific and Technological Research Council of Turkey(TUBITAK,No.113M141)
文摘In this study, the processing and mechanical properties of porous metal matrix composites(MMCs) composed of spheroidal cast iron chips(GGG40) and bronze chips(CuSn10) and formed by hot isostatic pressing were investigated. Bronze chips(CuSn10) were used as a matrix component, and spheroidal cast iron(GGG40) chips were used as a reinforcement component. The MMCs were produced with different CuSn10 contents(90 wt%, 80 wt%, 70 wt%, and 60 wt%). The hot isostatic pressing process was performed under three different pressures and temperatures. The produced MMCs were characterized using density tests, Brinell hardness tests, and compression tests. In addition, the consolidation mechanism was investigated by X-ray diffraction(XRD) analysis and scanning electron microscopy. The test results were compared with those for bulk CuSn10 and bulk GGG40. Mechanical tests results revealed that the metallic chips can be recycled by using hot pressing and that the mechanical properties of the produced MMCs were similar to those of bulk CuSn10. XRD and microscopy studies showed that no intermetallic compounds formed between the metallic chips. The results showed that the CuSn10 and GGG40 chips were consolidated by mechanical interlocking.
基金financially supported by the International Science and Technology Cooperation Program of China (No.2015DFA51430)the National Natural Science Foundation of China (No.51401010)the Aeronautical Science Foundation of China (No.2015ZF51069)
文摘The microstructural evolution of A356 machining chips in the semisolid state was studied at different temperatures and holding times. The results showed that the elongated α-Al grains first recrystallized in the semisolid state and then became globular with a high shape factor(SF). Both the temperature and the holding time clearly affected the grain size and SF. When the heating temperature or holding time was increased, the grain size and SF gradually increased and finally became stable. Moreover, the Vickers hardness of primary α-Al grains gradually decreased with increasing heating temperature. The optimal slurry for semisolid processing, with a good combination of grain size and SF, was obtained when the chips were held at 600℃ for 15 min. The semisolid slurry of A356 chips exhibited a lower coarsening rate of α-Al grains than those produced by most of the conventional semisolid processes. The coarsening coefficient was determined to be 436 μm^3·s^(-1) on the basis of the linear Lifshitz–Slyozov–Wagner(LSW) relationship.
文摘Objective:To evaluate the hazardous effects of fried potato chips upon the retina of two developmental stages of the albino rats aged 7 and 14 days from parturition.Methods:Pregnant rats were arranged into two groups:control pregnant rats and consequently their delivered newborns until reaching 7 and 14 days old from parturition and fried potato chips group in which pregnant rats at the 6th day of gestation maintained on diet formed of fried potato chips supplied from the market mixed with standard diet at a concentration of 50%per each till 7 and 14 postpartum.Three fold integrated approaches were adopted,namely,histological,ultrastructural and proteomic analysis.Results:Histological examination of the retina of the experimental offsprings revealed many histopathological changes,including massive degeneration,vacuolization and cell loss in the ganglion cell layer,as well as general reduction in retinal size.At the ultrastructural level,the retina of experimental offsprings exhibited number of deformities,including ill differentiated and degenerated nuclear layer,malformed and vacuolated pigment epithelium with vesiculated and fragmented rough endoplasmic reticulum,degenerated outer segment of photoreceptors,as well as swollen choriocapillaris and loss of neuronal cells.Proteomic analysis of retina of the two experimental developmental stages showed variations in the expressed proteins as a result of intoxication which illustrated the adverse toxic effects of fried potato chips upon the retina.Conclusions:It can be concluded that the effect of fried potato chips on the development of retina in rats may be due to the presence of acrylamide or its metabolite.
基金supported by the National Natural Science Research Foundation of China(61533016,11827803,31971244,31570947,11772036,11421202 and U20A20390)the National Key Research and Development Program of China(2016YFC1102202 and 2016YFC1101101)Beijing Natural Science Foundation(4194079)and the 111 Project(B13003).
文摘Endothelial cells arranged on the vessel lumen are constantly stimulated by blood flow,blood pressure and pressureinduced cyclic stretch.These stimuli are sensed through mechanical sensory structures and converted into a series of functional responses through mechanotransduction pathways.The process will eventually affect vascular health.Therefore,there has been an urgent need to establish in vitro endothelial biomechanics and mechanobiology of models,which reproduce three-dimensional structure vascular system.In recent years,the rapid development in microfluidic technology makes it possible to replicate the key structural and functionally biomechanical characteristics of vessels.Here,we summarized the progress of microfluidic chips used for the investigation of endothelial biomechanics and mechanobiology of the vascular system.Firstly,we elucidated the contribution of shear stress and circumferential stress,to vascular physiology.Then,we reviewed some applications using microfluidic technology in angiogenesis and vasculogenesis,endothelial permeability and mechanotransduction,as well as the blood-brain barrier under these physical forces.Finally,we discussed the future obstacles in terms of the development and application of microfluidic vascular chips.
文摘AZ91D magnesium alloy chips were adopted to prepare semi-solid billets.The chips were subjected to a series ofisothermal treatments for various holding times at 783?843 K after being compressed into billet at 523 K.The semi-solid microstructure of AZ91D magnesium alloy containing spherical solid particles was studied.The effects of reheating temperature and holding time on microstructures were investigated.And the semi-solid forming mechanism was discussed.The result shows that semi-solid billets with highly spheroidal and homogeneous grains can be prepared from chips by strain induced melt activation(SIMA) method.Meanwhile,it is found that increasing the heating temperature can accelerate the spheroidizing process and reduce the solid volume fraction.With the increase of the holding time,the solid particles become more globular,the grains grow slowly and the solid volume fraction slightly changes.At the same time,owing to the decrease ofinterfacial energy,the intragranular liquid phases form by the diffusion of solute atoms,the grain boundaries melt and grains separate from each other during the isothermal treatment.The grains gradually spheroidize and begin to merge with a further increase of the holding time.It is considered that the semi-solid forming process includes three stages:the recrystallization and the growth of grain stage,the semi-solid microstructure forming stage controlled by the diffusion of solute,and the spheroidization of solid particle stage controlled by the liquid-solid interface tension.
