Dry wear behavior of the rheo-casting Al-16Si-4Cu-0.5Mg alloy was investigated by micro-scratch and dry sliding weartests. Analyses of the microstructure, scratch grooves, wear tracks, worn surfaces and wear debris of...Dry wear behavior of the rheo-casting Al-16Si-4Cu-0.5Mg alloy was investigated by micro-scratch and dry sliding weartests. Analyses of the microstructure, scratch grooves, wear tracks, worn surfaces and wear debris of the alloy were carried out byoptical microscope and scanning electron microscope. The microstructural analysis showed that via rheo-processing, the primary Siwas refined and rounded, eutectics dispersed more homogenously, and even the skeleton AlFeMnSi phase was fragmented into facetshape. Micro-scratch test showed that the microstructural refinement resulted in better wear resistance. Dry sliding wear test revealedthat the rheo-processed sample exhibit obviously superior wear resistance because of the microstructure improvement. The dominantmechanism in mild wear condition is abrasion, but it turned to adhesion and oxidation in high applied load and fast sliding velocityconditions.展开更多
AIM: To study the significance of scoring systems assessing severity and prognostic factors in patients with colonic perforation. METHODS: A total of 26 patients (9 men, 17 women; mean age 72.7 ± 11.6 years) unde...AIM: To study the significance of scoring systems assessing severity and prognostic factors in patients with colonic perforation. METHODS: A total of 26 patients (9 men, 17 women; mean age 72.7 ± 11.6 years) underwent emergency operation for colorectal perforation in our institution between 1993 and 2005. Several clinical factors were measured preoperatively and 24 h postoperatively. Acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ), Mannheim peritonitis index (MPI) and peritonitis index of Altona (PIA Ⅱ) scores were calculated preoperatively. RESULTS: Overall postoperative mortality rate was 23.1% (6 patients). Compared with survivors, non- survivors displayed low blood pressure, low serum protein and high serum creatinine preoperatively, and low blood pressure, low white blood cell count, low pH, low PaO2/FiO2, and high serum creatinine postoperatively. APACHE Ⅱ score was significantly lower in survivors than in non-survivors (10.4 ± 3.84 vs 19.3 ± 2.87, P = 0.00003). Non-survivors tended to display high MPI score and low PIA Ⅱ score, but no signif icant difference was identif ied. CONCLUSION: Pre- and postoperative blood pressure and serum creatinine level appear related to prognosis of colonic perforation. APACHE Ⅱ score is most associated with prognosis and scores ≥ 20 are associated with signif icantly increased mortality rate.展开更多
Based on the principle of fully mechanized backflling and coal mining technology and combined with the Xingtai Coal Mine conditions, we mainly optimized the coal mining equipment and adjusted the coal mining method in...Based on the principle of fully mechanized backflling and coal mining technology and combined with the Xingtai Coal Mine conditions, we mainly optimized the coal mining equipment and adjusted the coal mining method in the Xingtai Coal Mine 7606 working face for implementation this technology. Firstly, we define the practical backfilling process as the ＂（from backfilling scraper conveyor＇s） head to tail back- filling, step by step swinging up of the tamping arm, gradual compacting, moving formed backfilling scra- per conveyor when the second tamping arm cannot pass and connecting the immediate roof by back material push front material movement＂. Meanwhile, the stress changes of backfill body in coal mined out area was monitored by stress sensors, and the roof caving law was analyzed by monitoring the dynamic subsidence of -210 west roadway of this face. The site tests results show that using this new backfilling and coal mining integrated technology, the production capacity in the 7606 working face can reach to 283,000 ton a year, and 282,000 ton of solid materials （waste and fly ash） is backfilled, which meets the needs of high production and efficiency. The goaf was compactly backfilled with solid material and the strata behavior was quite desirable, with an actual maximum vertical stress of the backfill body of 5.5 MPa. Backfill body control the movement of overburden within a certain range, and there is no col- lapses of major areas in the overlying strata upon backfilled gob. The maximum subsidence and speed were 231 mm and 15.75 mm/d respectively, which proved the practical significance of this integrated technology.展开更多
A nano probe system which can measure precise contact force in mN scale was demonstrated. The nano probe micro parts or optical parts in nanometer range resolution and scratch was originally designed for on-machine me...A nano probe system which can measure precise contact force in mN scale was demonstrated. The nano probe micro parts or optical parts in nanometer range resolution and scratch was originally designed for on-machine measuring applications and one kind of contact type measuring probes was designed for miniaturized or microfactory system. It ideally should be of small size and able to measure surface topography in nanometer scale. A commercial capacitive displacement sensor was proposed. It was a new concept in nano probe systems which can measure the displacement of shaft driven by the variation of surface topography. The nano probe mainly consisted of three parts： a capacitive displacement sensor, a porous type air slide and a contact probe part with various tip radiuses. The porous type air slide assured the shaft slided smoothly with controllable normal force in mN scale and had high positioning accuracy. The probe part which was directly in contact with target surface, can be applied to micro/nanoscale scratching as well as the measurement of sample topography by a simple tip change.展开更多
This paper proposes an analytical model to describe rock drilling processes using drag bits and rotary drills, and to induce relations among rock properties, bit shapes, and drilling parameters （rotary speed, thrust,...This paper proposes an analytical model to describe rock drilling processes using drag bits and rotary drills, and to induce relations among rock properties, bit shapes, and drilling parameters （rotary speed, thrust, torque, and stroke）. In this model, a drilling process is divided into successive cycles. Each cycle includes two motions： feed and cutting. According to this model, drilling torque includes four components generated from cutting, friction, feed, and idle running respectively, the first three items are all proportional to the UCS （uniaxial compressive strength） when the penetration rate is constant. Laboratory tests verified the correctness and effectiveness of the proposed model qualitatively. Especially, the influence of friction on the flank face and the idle running was confirmed. Field experiments were performed. The results showed good correlation between the torque, penetration rate, and UCS. The proposed model and equations engender the possibility of eliminating useless components of cutting forces when investigating the relation between mechanical data and physical properties of rocks.展开更多
Low dielectric constant materials/Cu interconnects integration technology provides the direction as well as the challenges in the fabrication of integrated circuits(IC) wafers during copper electrochemical-mechanical ...Low dielectric constant materials/Cu interconnects integration technology provides the direction as well as the challenges in the fabrication of integrated circuits(IC) wafers during copper electrochemical-mechanical polishing(ECMP). These challenges arise primarily from the mechanical fragility of such dielectrics, in which the undesirable scratches are prone to produce. To mitigate this problem, a new model is proposed to predict the initiation of scratching based on the mechanical properties of passive layer and copper substrate. In order to deduce the ratio of the passive layer yield strength to the substrate yield strength and the layer thickness, the limit analysis solution of surface scratch under Berkovich indenter is used to analyze the nano-scratch experimental measurements. The modulus of the passive layer can be calculated by the nano-indentation test combined with the FEM simulation. It is found that the film modulus is about 30% of the substrate modulus. Various regimes of scratching are delineated by FEM modeling and the results are verified by experimental data.展开更多
Objective To observe the antihypertensive efficacy of guasha for essential hypertension.Methods Thirty-four cases of essential hypertension were treated with guasha along the following route of the governor vessel,the...Objective To observe the antihypertensive efficacy of guasha for essential hypertension.Methods Thirty-four cases of essential hypertension were treated with guasha along the following route of the governor vessel,the bladder meridian and the gallbladder meridian and the hand yangming large intestine meridian and the foot yangming stomach meridian on the head,neck and back.The gentle stimulation and supplementation method was applied for deficiency syndrome and the heavy stimulation and drainage method was applied for excess syndrome.Two times a week,total 8 treatments were given Blood pressure was measured at different time points from2：00PM to 8：00PM（2：00PM,2：30PM,3：00PM,3：30PM,4：00PM,5：00PM,6：00PM,8：00PM） before the first application of guasha and after the eighth treatment,respectively.Results Compared with each time point before the first application of guasha,there were statistically significant differences of blood pressure at each corresponding time point after the eighth guasha（all P〈0.01）.Blood pressure reduced from（147.42 ± 13.04） /（86.27 ± 11.91） mmHg to（129.35 ± 9.16） /（80.15 ± 9.41） mmHg;the score of grading and quantifying of TCM pattern significantly decreased（P〈0.01）.The score of quality of life scale of Duchenne hypertension significantly increased（P〈0.01）.Conclusion Blood pressure can be effectively reduced by adopting guasha,and the clinical symptoms and quality of life of patients with essential hypertension can be improved.展开更多
基金Project(51404153)supported by the National Natural Science Foundation of ChinaProject supported by the Joint Ph D Program of the China Scholarship Council(CSC)
文摘Dry wear behavior of the rheo-casting Al-16Si-4Cu-0.5Mg alloy was investigated by micro-scratch and dry sliding weartests. Analyses of the microstructure, scratch grooves, wear tracks, worn surfaces and wear debris of the alloy were carried out byoptical microscope and scanning electron microscope. The microstructural analysis showed that via rheo-processing, the primary Siwas refined and rounded, eutectics dispersed more homogenously, and even the skeleton AlFeMnSi phase was fragmented into facetshape. Micro-scratch test showed that the microstructural refinement resulted in better wear resistance. Dry sliding wear test revealedthat the rheo-processed sample exhibit obviously superior wear resistance because of the microstructure improvement. The dominantmechanism in mild wear condition is abrasion, but it turned to adhesion and oxidation in high applied load and fast sliding velocityconditions.
文摘AIM: To study the significance of scoring systems assessing severity and prognostic factors in patients with colonic perforation. METHODS: A total of 26 patients (9 men, 17 women; mean age 72.7 ± 11.6 years) underwent emergency operation for colorectal perforation in our institution between 1993 and 2005. Several clinical factors were measured preoperatively and 24 h postoperatively. Acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ), Mannheim peritonitis index (MPI) and peritonitis index of Altona (PIA Ⅱ) scores were calculated preoperatively. RESULTS: Overall postoperative mortality rate was 23.1% (6 patients). Compared with survivors, non- survivors displayed low blood pressure, low serum protein and high serum creatinine preoperatively, and low blood pressure, low white blood cell count, low pH, low PaO2/FiO2, and high serum creatinine postoperatively. APACHE Ⅱ score was significantly lower in survivors than in non-survivors (10.4 ± 3.84 vs 19.3 ± 2.87, P = 0.00003). Non-survivors tended to display high MPI score and low PIA Ⅱ score, but no signif icant difference was identif ied. CONCLUSION: Pre- and postoperative blood pressure and serum creatinine level appear related to prognosis of colonic perforation. APACHE Ⅱ score is most associated with prognosis and scores ≥ 20 are associated with signif icantly increased mortality rate.
基金Financial supports for this work provided by the National Natural Science Foundation of China (No. 51074165)the Key Program of National Natural Science Foundation of China (No.50834004)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (No.SZBF2011-6-B35)
文摘Based on the principle of fully mechanized backflling and coal mining technology and combined with the Xingtai Coal Mine conditions, we mainly optimized the coal mining equipment and adjusted the coal mining method in the Xingtai Coal Mine 7606 working face for implementation this technology. Firstly, we define the practical backfilling process as the ＂（from backfilling scraper conveyor＇s） head to tail back- filling, step by step swinging up of the tamping arm, gradual compacting, moving formed backfilling scra- per conveyor when the second tamping arm cannot pass and connecting the immediate roof by back material push front material movement＂. Meanwhile, the stress changes of backfill body in coal mined out area was monitored by stress sensors, and the roof caving law was analyzed by monitoring the dynamic subsidence of -210 west roadway of this face. The site tests results show that using this new backfilling and coal mining integrated technology, the production capacity in the 7606 working face can reach to 283,000 ton a year, and 282,000 ton of solid materials （waste and fly ash） is backfilled, which meets the needs of high production and efficiency. The goaf was compactly backfilled with solid material and the strata behavior was quite desirable, with an actual maximum vertical stress of the backfill body of 5.5 MPa. Backfill body control the movement of overburden within a certain range, and there is no col- lapses of major areas in the overlying strata upon backfilled gob. The maximum subsidence and speed were 231 mm and 15.75 mm/d respectively, which proved the practical significance of this integrated technology.
基金Project supported by National Core Research Center (NCRC) and Chosun University, Korea
文摘A nano probe system which can measure precise contact force in mN scale was demonstrated. The nano probe micro parts or optical parts in nanometer range resolution and scratch was originally designed for on-machine measuring applications and one kind of contact type measuring probes was designed for miniaturized or microfactory system. It ideally should be of small size and able to measure surface topography in nanometer scale. A commercial capacitive displacement sensor was proposed. It was a new concept in nano probe systems which can measure the displacement of shaft driven by the variation of surface topography. The nano probe mainly consisted of three parts： a capacitive displacement sensor, a porous type air slide and a contact probe part with various tip radiuses. The porous type air slide assured the shaft slided smoothly with controllable normal force in mN scale and had high positioning accuracy. The probe part which was directly in contact with target surface, can be applied to micro/nanoscale scratching as well as the measurement of sample topography by a simple tip change.
文摘This paper proposes an analytical model to describe rock drilling processes using drag bits and rotary drills, and to induce relations among rock properties, bit shapes, and drilling parameters （rotary speed, thrust, torque, and stroke）. In this model, a drilling process is divided into successive cycles. Each cycle includes two motions： feed and cutting. According to this model, drilling torque includes four components generated from cutting, friction, feed, and idle running respectively, the first three items are all proportional to the UCS （uniaxial compressive strength） when the penetration rate is constant. Laboratory tests verified the correctness and effectiveness of the proposed model qualitatively. Especially, the influence of friction on the flank face and the idle running was confirmed. Field experiments were performed. The results showed good correlation between the torque, penetration rate, and UCS. The proposed model and equations engender the possibility of eliminating useless components of cutting forces when investigating the relation between mechanical data and physical properties of rocks.
基金Project(50975058) supported by the National Natural Science Foundation of China
文摘Low dielectric constant materials/Cu interconnects integration technology provides the direction as well as the challenges in the fabrication of integrated circuits(IC) wafers during copper electrochemical-mechanical polishing(ECMP). These challenges arise primarily from the mechanical fragility of such dielectrics, in which the undesirable scratches are prone to produce. To mitigate this problem, a new model is proposed to predict the initiation of scratching based on the mechanical properties of passive layer and copper substrate. In order to deduce the ratio of the passive layer yield strength to the substrate yield strength and the layer thickness, the limit analysis solution of surface scratch under Berkovich indenter is used to analyze the nano-scratch experimental measurements. The modulus of the passive layer can be calculated by the nano-indentation test combined with the FEM simulation. It is found that the film modulus is about 30% of the substrate modulus. Various regimes of scratching are delineated by FEM modeling and the results are verified by experimental data.
基金Supported by National Natural Science Foundation of China:a study on biological effects and the mechanism of guasha with different methods(81173346)
文摘Objective To observe the antihypertensive efficacy of guasha for essential hypertension.Methods Thirty-four cases of essential hypertension were treated with guasha along the following route of the governor vessel,the bladder meridian and the gallbladder meridian and the hand yangming large intestine meridian and the foot yangming stomach meridian on the head,neck and back.The gentle stimulation and supplementation method was applied for deficiency syndrome and the heavy stimulation and drainage method was applied for excess syndrome.Two times a week,total 8 treatments were given Blood pressure was measured at different time points from2：00PM to 8：00PM（2：00PM,2：30PM,3：00PM,3：30PM,4：00PM,5：00PM,6：00PM,8：00PM） before the first application of guasha and after the eighth treatment,respectively.Results Compared with each time point before the first application of guasha,there were statistically significant differences of blood pressure at each corresponding time point after the eighth guasha（all P〈0.01）.Blood pressure reduced from（147.42 ± 13.04） /（86.27 ± 11.91） mmHg to（129.35 ± 9.16） /（80.15 ± 9.41） mmHg;the score of grading and quantifying of TCM pattern significantly decreased（P〈0.01）.The score of quality of life scale of Duchenne hypertension significantly increased（P〈0.01）.Conclusion Blood pressure can be effectively reduced by adopting guasha,and the clinical symptoms and quality of life of patients with essential hypertension can be improved.
