AIM:To determine the efficacy and safety of rapid induction therapy with oral tacrolimus without a meal in steroid-refractory ulcerative colitis(UC)patients.METHODS:This was a prospective,multicenter,observational stu...AIM:To determine the efficacy and safety of rapid induction therapy with oral tacrolimus without a meal in steroid-refractory ulcerative colitis(UC)patients.METHODS:This was a prospective,multicenter,observational study.Between May 2010 and August 2012,49 steroid-refractory UC patients(55 flare-ups)were consecutively enrolled.All patients were treated with oral tacrolimus without a meal at an initial dose of 0.1mg/kg per day.The dose was adjusted to maintain trough whole-blood levels of 10-15 ng/m L for the first 2 wk.Induction of remission at 2 and 4 wk after tacrolimus treatment initiation was evaluated using Lichtiger’s clinical activity index(CAI).RESULTS:The mean CAI was 12.6±3.6 at onset.Within the first 7 d,93.5%of patients maintained high trough levels(10-15 ng/m L).The CAI significantly decreased beginning 2 d after treatment initiation.At 2wk,73.1%of patients experienced clinical responses.After tacrolimus initiation,31.4%and 75.6%of patients achieved clinical remission at 2 and 4 wk,respectively.Treatment was well tolerated.CONCLUSION:Rapid induction therapy with oral tacrolimus shortened the time to achievement of appropriate trough levels and demonstrated a high remission rate 28 d after treatment initiation.Rapid induction therapy with oral tacrolimus appears to be a useful therapy for the treatment of refractory UC.展开更多
AIM: To evaluate the efficacy of sequential vs hybrid therapy in patients with Helicobacter pylori(H. pylori) infection.METHODS: From March 2013 to May 2014,one hundred and seventy-five H. pylori infected patients who...AIM: To evaluate the efficacy of sequential vs hybrid therapy in patients with Helicobacter pylori(H. pylori) infection.METHODS: From March 2013 to May 2014,one hundred and seventy-five H. pylori infected patients who had not been treated for H. pylori before wererandomized to receive either sequential therapy(rabeprazole 20 mg and amoxicillin 1 g twice daily for 5 d,followed by rabeprazole 20 mg,clarithromycin 500 mg and metronidazole 500 mg twice daily for 5 d) or hybrid therapy(rabeprazole 20 mg and amoxicillin 1 g for 7 d,followed by rabeprazole 20 mg,amoxicillin 1 g,clarithromycin 500 mg and metronidazole 500 mg twice daily for 7 d). H. pylori status was confirmed by positive results of both rapid urease test and histology examination or a positive result of culture. Eradication efficacy was assessed by follow-up endoscopy with rapid urease test and histological examination 8 wk after the end of anti-H. pylori therapy,or 13C-urea breath test at least 4 wk after completion of treatment. The primary outcome was H. pylori eradication by intension-to-treat(ITT) and per-protocol(PP) analyses.RESULTS: One hundred and sixty-seven patients(83 patients in the sequential group and 84 patients in the hybrid group) completed the study. The compliance rates were 97.6% and 97.7% for the two groups,respectively. The eradication rate was 78.2% for the sequential group and 92% for the hybrid group by ITT analysis(P = 0.01). The eradication rate was 81.9% for the sequential group and 96.4% for the hybrid group by PP analysis(P = 0.01). Univariate analysis for the clinical and bacterial factors did not identify any risk factors associated with treatment failure. Severe adverse events were observed in 2.3% of patients in the sequential group and 2.4% of those in the hybrid group.CONCLUSION: Due to a grade A(> 95%) success rate for H. pylori eradication by PP analysis,similar compliance and adverse events,hybrid therapy seems to be an appropriate eradication regimen in Taiwan.展开更多
A thermal fatigue behaviour of Co-based alloy coating obtained by laser surface meltcasting on the high temperature alloy GH33 was studied.The results show that after each time of thermal cycling,the final residual st...A thermal fatigue behaviour of Co-based alloy coating obtained by laser surface meltcasting on the high temperature alloy GH33 was studied.The results show that after each time of thermal cycling,the final residual stress was formed in the melt-casting layer which is attributed to the thermal stress and structural stress.Through the first 50 times of thermal cycling,the morphology of coating still inherits the laser casting one,but the dendrites get bigger;After the second 50 times of thermal cycling,corrosion pits emerge from coating,and mostly in the places where coating and substrate meet.The fatigue damage type of coating belongs to stress corrosion.展开更多
The ther m al deco m position mechanism of a m m oniu m thiotungstate of the size of 63 ～75 μmin H2 has been investigated by D T A and X R D methods . The ther m al deco m position activationenergies and the ord...The ther m al deco m position mechanism of a m m oniu m thiotungstate of the size of 63 ～75 μmin H2 has been investigated by D T A and X R D methods . The ther m al deco m position activationenergies and the orders of a m m oniu m thiotu ngstate were calculated by means of Kissinger , Freem an Carroll and Coast Redfern m ethods . It w as also obtained that therm al deco m posi tion is cond ucted according to four reaction equations :( N H4) 2 W S4· H2 O(s) ( N H4) 2 W S4(s) + H2 O(g) W S2(s) + 2 N H3(g) + H2(g) + 2 S(s) + H2 O(g) W S2(s) + 2 N H3(g) + 2 H2 S(g) + H2 O(g) W S2(s) + W(s) + 2 N H3(g) + 2 H2 S(g) + H2 O(g) .展开更多
Several nc-TiN/a-TiB2 thin films comprised of nanocrystalline (nc-) TiN and amor phous (a-) TiB2 phases were deposited on Si(100) at room temperature by reactive unbalanced dc magnetron sputtering, followed by vacuum ...Several nc-TiN/a-TiB2 thin films comprised of nanocrystalline (nc-) TiN and amor phous (a-) TiB2 phases were deposited on Si(100) at room temperature by reactive unbalanced dc magnetron sputtering, followed by vacuum annealed at 400, 600, 80 0 and 1000℃ for 1h, respectively. Effects of B content on microstructure, mecha nical behaviors and thermal microstructure stability have been investigated by X -ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and nanoindentation measurements. The results indicated that B addition greatly affected both microstructure and mechanical behavior of nc-Ti N/a-TiB2 thin films. With increasing B content the grain size decreased. A maxim um hardness value of about 33GPa was obtained at B content of about 19at.%. The improved mechanical properties of nc-TiN/a-TiB2 films with the addition of B int o TiN were attributed to their densified microstructure with development of fine grain size. Only addition of sufficient B could restrain grain growth during an nealing. High B content resulted in high microstructure stability. The crystalli zation of amorphous matrix occurred at about 800℃, forming TiB or TiB2 crystall ite, depending on B content. Before that no change in bonding configuration was found.展开更多
Gastric cancer is the fourth most common cancer,and the second-highest cause of cancer-related deaths worldwide.Despite extensive research to identify novel diagnostic and therapeutic agents,patients with advanced gas...Gastric cancer is the fourth most common cancer,and the second-highest cause of cancer-related deaths worldwide.Despite extensive research to identify novel diagnostic and therapeutic agents,patients with advanced gastric cancer suffer from a poor quality of life and poor prognosis,and treatment is dependent mainly on conventional cytotoxic chemotherapy.To improve the quality of life and survival of gastric cancer patients,a better understanding of the underlying molecular pathologies,and their application towards the development of novel targeted therapies,is urgently needed.Chemokines are a group of small proteins associated with cytoskeletal rearrangements,the directional migration of several cell types during development and physiology,and the host immune response via interactions with G-protein coupled receptors.There is also growing evidence to suggest that chemokines not only play a role in the immune system,but are also involved in the development and progression of tumors.In gastric cancer,CXC chemokines and chemokine receptors regulate the trafficking of cells in and out of the tumor microenvironment.CXC chemokines and their receptors can also directly influence tumorigenesis by modulating tumor transformation,survival,growth,invasion and metastasis,as well as indirectly by regulating angiogenesis,and tumor-leukocyte interactions.In this review,we will focus on the roles of CXC chemokines and their receptors in the development,progression,and metastasis of gastric tumors,and discuss their therapeutic potential for gastric cancer.展开更多
AIM: To assess the endoscopic activity before and after a one-year period of biological therapy and to evaluate the frequency of relapses and need for retreatment after stopping the biologicals in patients with Crohn&...AIM: To assess the endoscopic activity before and after a one-year period of biological therapy and to evaluate the frequency of relapses and need for retreatment after stopping the biologicals in patients with Crohn’s disease (CD) and ulcerative colitis (UC).展开更多
Based on vibration analysis, single-layered graphene sheet （SLGS） with multiple attached nanoparticles is developed as nanoscale mass sensor in thermal environments. Graphene sensors are assumed to be in simplysuppo...Based on vibration analysis, single-layered graphene sheet （SLGS） with multiple attached nanoparticles is developed as nanoscale mass sensor in thermal environments. Graphene sensors are assumed to be in simplysupported configuration. Based on the nonlocal plate the- ory which incorporates size effects into the classical theory, closed-form expressions lot the frequencies and relative fre- quency shills of SLGS-based mass sensor are derived using the Galerkin method. The suggested model is justified by a good agreement between the results given by the present model and available data in literature. The effects of tem- perature difference, nonlocal parameter, the location of the nanoparticle and the number of nanoparticles on the relative frequency shift of the mass sensor are also elucidated. The obtained results show that the sensitivity of the SLGS- based mass sensor increases with increasing temperature difference.展开更多
The role of multicomponent rare earth oxides in phase stability, thermophysical properties and sintering for ZrO2-based thermal barrier coatings （TBCs） materials is investigated. 8YSZ codoped with 3 mol% Gd2O3 and 3...The role of multicomponent rare earth oxides in phase stability, thermophysical properties and sintering for ZrO2-based thermal barrier coatings （TBCs） materials is investigated. 8YSZ codoped with 3 mol% Gd2O3 and 3 mol% Yb2O3 （GYb-YSZ） powders are synthesized by solid state reaction for 24 h at various temperatures. As temperature increases, stabilizers are dissolved into zirconia matrix gradually. Synthesized at 1 500 °C, GYb-YSZ is basically composed of cubic phase. GYb-YSZ exhibits excellent phase stability and sinters lower than 8YSZ by nearly three times. The thermal conductivity of GYb-YSZ is much lower than that of 8YSZ, and the thermal expansion coefficient of GYb-YSZ is comparable to that of 8YSZ. The influence of Gd2O3 and Yb2O3 co-doping on phase stability, thermal conductivity and sintering of 8YSZ is discussed.展开更多
Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation （during loading） and vanishing （in unloading） of a high strain （martensite） domain. The two events...Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation （during loading） and vanishing （in unloading） of a high strain （martensite） domain. The two events are accompanied by a rapid stress drop/rise due to the formation/vanishing of do- main fronts. From a thermodynamic point of view, both are instability phenomena that occur once the system reaches its critical state. This paper investigates the stability of a shrink- ing cylindrical domain in a tube configuration during unload- ing. The energetics and thermodynamic driving force of the cylindrical domain are quantified by using an elastic inclu- sion model. It is demonstrated that the two domain fronts ex- hibit strong interaction when they come close to each other, which brings a peak in the total energy and a sign change in the thermodynamic driving force. It is proved that such domain front interaction plays an important role in control- ling the stability of the domain and in the occurrence of stress jumps during domain vanishing. It is also shown that the pro- cess is governed by two nondimensional length scales （the normalized tube length and normalized wall-thickness） and that the length scale dependence of the critical domain length and stress jump for the domain vanishing can be quantified by the elastic inclusion model.展开更多
Al2 O3 - SiC - SiAION composite specimens have been prepared using fused alumina, ultra fine α-Al2O3, Si and Al powders as starting materials and liquid phenol formaldehyde resin as binder and firing at 1 500 ℃ for ...Al2 O3 - SiC - SiAION composite specimens have been prepared using fused alumina, ultra fine α-Al2O3, Si and Al powders as starting materials and liquid phenol formaldehyde resin as binder and firing at 1 500 ℃ for 3 h in carbon embedded condition. Thermo-mechanical properties of Al2 O3 - SiC - SiAlON composites have been studied. The results show ： （ 1 ） Al2 O3 - SiC - SiAION composites can be prepared and sintered at 1 500 ℃ under carbon embedded condition. When Si/Al ratio is 8/0 and 7/1, the prepared composite is Al2O3 - SiC - O＇ -SiAlON; when Si/Al ratio is 5/3 and 3/5, the pre- pared composite is Al2 O3 - SiC - β-SiAION. （ 2 ） The composites possess high temperature strength properties. Hot modulus of rupture at 1 400 ℃ is 10 - 30 MPa. They are in elastic range up to 1 000 ℃, after which plastic deformation is observed; even at 1 400 ℃, amount of deformation is relatively low. （3） The com- posites possess good thermal shock resistance, their resid- ual strength ratio （AT = 1 100 ℃ ） is 65% - 80%. （4） The marked improvement in thermo-mechanical properties of Al2O3 - SiC - SiAlON composites may be at- tributed to the in-situ formation of SiC, SiAlON and AIN, the fibrous SiC, columnar SiAlON and tabular-like AlN fill in the corundum skeleton structure creating strengthening and toughening effects.展开更多
Rocks are composed of mineral particles and micropores between mineral which has a great influence on the mechanical properties of rocks. In this paper, based on the theory of locked-in stress developed by academician...Rocks are composed of mineral particles and micropores between mineral which has a great influence on the mechanical properties of rocks. In this paper, based on the theory of locked-in stress developed by academician Chen Zongji, the locked-in stress problem in underground rock is simulated by the thermal expansion of hard rubber particles. The pore inclusion in rock is assumed to be uniformly distributed spherical cavities. Using the thermal stress theory, the stress of rock with a spherical pore inclusion is equivalent to the thermal stress generated by the spherical hard rubber inclusion. The elastic theory formula of the temperature increment and the equivalent pore pressure of the spherical hard rubber inclusion is derived. The numerical simulation of the rock mass model with a spherical hard rubber inclusion is carried out and compared to the theoretical calculation results<span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> the results show that they are consistent. The method proposed by this paper for simulating stress distribution in rock by thermal stress is reasonable and feasible</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> it has a positive meaning for further study of mechanic phenomenon of rock with micropore inclusion.</span>展开更多
The objective of the present paper is to develop nonlinear finite element method models for predicting the weld-induced initial deflection and residual stress of plating in steel stiffened-plate structures. For this p...The objective of the present paper is to develop nonlinear finite element method models for predicting the weld-induced initial deflection and residual stress of plating in steel stiffened-plate structures. For this purpose, three-dimensional thermo-elastic-plastic finite element method computations are performed with varying plate thickness and weld bead length (leg length) in welded plate panels, the latter being associated with weld heat input. The finite element models are verified by a comparison with experimental database which was obtained by the authors in separate studies with full scale measurements. It is concluded that the nonlinear finite element method models developed in the present paper are very accurate in terms of predicting the weld-induced initial imperfections of steel stiffened plate structures. Details of the numerical computations together with test database are documented.展开更多
文摘AIM:To determine the efficacy and safety of rapid induction therapy with oral tacrolimus without a meal in steroid-refractory ulcerative colitis(UC)patients.METHODS:This was a prospective,multicenter,observational study.Between May 2010 and August 2012,49 steroid-refractory UC patients(55 flare-ups)were consecutively enrolled.All patients were treated with oral tacrolimus without a meal at an initial dose of 0.1mg/kg per day.The dose was adjusted to maintain trough whole-blood levels of 10-15 ng/m L for the first 2 wk.Induction of remission at 2 and 4 wk after tacrolimus treatment initiation was evaluated using Lichtiger’s clinical activity index(CAI).RESULTS:The mean CAI was 12.6±3.6 at onset.Within the first 7 d,93.5%of patients maintained high trough levels(10-15 ng/m L).The CAI significantly decreased beginning 2 d after treatment initiation.At 2wk,73.1%of patients experienced clinical responses.After tacrolimus initiation,31.4%and 75.6%of patients achieved clinical remission at 2 and 4 wk,respectively.Treatment was well tolerated.CONCLUSION:Rapid induction therapy with oral tacrolimus shortened the time to achievement of appropriate trough levels and demonstrated a high remission rate 28 d after treatment initiation.Rapid induction therapy with oral tacrolimus appears to be a useful therapy for the treatment of refractory UC.
文摘AIM: To evaluate the efficacy of sequential vs hybrid therapy in patients with Helicobacter pylori(H. pylori) infection.METHODS: From March 2013 to May 2014,one hundred and seventy-five H. pylori infected patients who had not been treated for H. pylori before wererandomized to receive either sequential therapy(rabeprazole 20 mg and amoxicillin 1 g twice daily for 5 d,followed by rabeprazole 20 mg,clarithromycin 500 mg and metronidazole 500 mg twice daily for 5 d) or hybrid therapy(rabeprazole 20 mg and amoxicillin 1 g for 7 d,followed by rabeprazole 20 mg,amoxicillin 1 g,clarithromycin 500 mg and metronidazole 500 mg twice daily for 7 d). H. pylori status was confirmed by positive results of both rapid urease test and histology examination or a positive result of culture. Eradication efficacy was assessed by follow-up endoscopy with rapid urease test and histological examination 8 wk after the end of anti-H. pylori therapy,or 13C-urea breath test at least 4 wk after completion of treatment. The primary outcome was H. pylori eradication by intension-to-treat(ITT) and per-protocol(PP) analyses.RESULTS: One hundred and sixty-seven patients(83 patients in the sequential group and 84 patients in the hybrid group) completed the study. The compliance rates were 97.6% and 97.7% for the two groups,respectively. The eradication rate was 78.2% for the sequential group and 92% for the hybrid group by ITT analysis(P = 0.01). The eradication rate was 81.9% for the sequential group and 96.4% for the hybrid group by PP analysis(P = 0.01). Univariate analysis for the clinical and bacterial factors did not identify any risk factors associated with treatment failure. Severe adverse events were observed in 2.3% of patients in the sequential group and 2.4% of those in the hybrid group.CONCLUSION: Due to a grade A(> 95%) success rate for H. pylori eradication by PP analysis,similar compliance and adverse events,hybrid therapy seems to be an appropriate eradication regimen in Taiwan.
基金Project Sponsored by Committee on Science and Technology of Guizhou Province(943068)
文摘A thermal fatigue behaviour of Co-based alloy coating obtained by laser surface meltcasting on the high temperature alloy GH33 was studied.The results show that after each time of thermal cycling,the final residual stress was formed in the melt-casting layer which is attributed to the thermal stress and structural stress.Through the first 50 times of thermal cycling,the morphology of coating still inherits the laser casting one,but the dendrites get bigger;After the second 50 times of thermal cycling,corrosion pits emerge from coating,and mostly in the places where coating and substrate meet.The fatigue damage type of coating belongs to stress corrosion.
文摘The ther m al deco m position mechanism of a m m oniu m thiotungstate of the size of 63 ～75 μmin H2 has been investigated by D T A and X R D methods . The ther m al deco m position activationenergies and the orders of a m m oniu m thiotu ngstate were calculated by means of Kissinger , Freem an Carroll and Coast Redfern m ethods . It w as also obtained that therm al deco m posi tion is cond ucted according to four reaction equations :( N H4) 2 W S4· H2 O(s) ( N H4) 2 W S4(s) + H2 O(g) W S2(s) + 2 N H3(g) + H2(g) + 2 S(s) + H2 O(g) W S2(s) + 2 N H3(g) + 2 H2 S(g) + H2 O(g) W S2(s) + W(s) + 2 N H3(g) + 2 H2 S(g) + H2 O(g) .
文摘Several nc-TiN/a-TiB2 thin films comprised of nanocrystalline (nc-) TiN and amor phous (a-) TiB2 phases were deposited on Si(100) at room temperature by reactive unbalanced dc magnetron sputtering, followed by vacuum annealed at 400, 600, 80 0 and 1000℃ for 1h, respectively. Effects of B content on microstructure, mecha nical behaviors and thermal microstructure stability have been investigated by X -ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and nanoindentation measurements. The results indicated that B addition greatly affected both microstructure and mechanical behavior of nc-Ti N/a-TiB2 thin films. With increasing B content the grain size decreased. A maxim um hardness value of about 33GPa was obtained at B content of about 19at.%. The improved mechanical properties of nc-TiN/a-TiB2 films with the addition of B int o TiN were attributed to their densified microstructure with development of fine grain size. Only addition of sufficient B could restrain grain growth during an nealing. High B content resulted in high microstructure stability. The crystalli zation of amorphous matrix occurred at about 800℃, forming TiB or TiB2 crystall ite, depending on B content. Before that no change in bonding configuration was found.
基金Supported by Basic Science Research Program through the National Research of Korea(NRF)funded by the Ministry of Education,Science and Technology,NRF-2009-0076540,NRF-2009-0067256
文摘Gastric cancer is the fourth most common cancer,and the second-highest cause of cancer-related deaths worldwide.Despite extensive research to identify novel diagnostic and therapeutic agents,patients with advanced gastric cancer suffer from a poor quality of life and poor prognosis,and treatment is dependent mainly on conventional cytotoxic chemotherapy.To improve the quality of life and survival of gastric cancer patients,a better understanding of the underlying molecular pathologies,and their application towards the development of novel targeted therapies,is urgently needed.Chemokines are a group of small proteins associated with cytoskeletal rearrangements,the directional migration of several cell types during development and physiology,and the host immune response via interactions with G-protein coupled receptors.There is also growing evidence to suggest that chemokines not only play a role in the immune system,but are also involved in the development and progression of tumors.In gastric cancer,CXC chemokines and chemokine receptors regulate the trafficking of cells in and out of the tumor microenvironment.CXC chemokines and their receptors can also directly influence tumorigenesis by modulating tumor transformation,survival,growth,invasion and metastasis,as well as indirectly by regulating angiogenesis,and tumor-leukocyte interactions.In this review,we will focus on the roles of CXC chemokines and their receptors in the development,progression,and metastasis of gastric tumors,and discuss their therapeutic potential for gastric cancer.
基金Supported by Shantou University Medical College Clinical Research Enhancement Initiative,and Research and Travel Grants from the Science and Technology Key Project of Shantou City,China,2012,No.2012-165-131
文摘AIM: To establish the feasibility of simultaneous modulated accelerated radiation therapy (SMART) in esophageal cancer (EC).
基金Supported by TAMOP-4.2.2.A-11/1/KONV-2012-0035,TA-MOP-4.2.2-A-11/1/KONV-2012-0052 TAMOP-4.2.2.A-11/1/KONV-2012-0073OTKA Research Proposal PD 105948(PI:Klaudia Farkas)
文摘AIM: To assess the endoscopic activity before and after a one-year period of biological therapy and to evaluate the frequency of relapses and need for retreatment after stopping the biologicals in patients with Crohn’s disease (CD) and ulcerative colitis (UC).
文摘Based on vibration analysis, single-layered graphene sheet （SLGS） with multiple attached nanoparticles is developed as nanoscale mass sensor in thermal environments. Graphene sensors are assumed to be in simplysupported configuration. Based on the nonlocal plate the- ory which incorporates size effects into the classical theory, closed-form expressions lot the frequencies and relative fre- quency shills of SLGS-based mass sensor are derived using the Galerkin method. The suggested model is justified by a good agreement between the results given by the present model and available data in literature. The effects of tem- perature difference, nonlocal parameter, the location of the nanoparticle and the number of nanoparticles on the relative frequency shift of the mass sensor are also elucidated. The obtained results show that the sensitivity of the SLGS- based mass sensor increases with increasing temperature difference.
基金National Natural Science Foundation of China (50771009, 50731001)National Basic Research Program of China (2010CB631200)Research Fund for the Doctoral Program of Higher Education of China (20070006017)
文摘The role of multicomponent rare earth oxides in phase stability, thermophysical properties and sintering for ZrO2-based thermal barrier coatings （TBCs） materials is investigated. 8YSZ codoped with 3 mol% Gd2O3 and 3 mol% Yb2O3 （GYb-YSZ） powders are synthesized by solid state reaction for 24 h at various temperatures. As temperature increases, stabilizers are dissolved into zirconia matrix gradually. Synthesized at 1 500 °C, GYb-YSZ is basically composed of cubic phase. GYb-YSZ exhibits excellent phase stability and sinters lower than 8YSZ by nearly three times. The thermal conductivity of GYb-YSZ is much lower than that of 8YSZ, and the thermal expansion coefficient of GYb-YSZ is comparable to that of 8YSZ. The influence of Gd2O3 and Yb2O3 co-doping on phase stability, thermal conductivity and sintering of 8YSZ is discussed.
基金supported by the Hong Kong Research Grants Council (GRF619511)the National Natural Science Foundation of China (11128204)
文摘Under isothermal quasi-static stretching the phase transition of a superelastic NiTi tube involves the formation （during loading） and vanishing （in unloading） of a high strain （martensite） domain. The two events are accompanied by a rapid stress drop/rise due to the formation/vanishing of do- main fronts. From a thermodynamic point of view, both are instability phenomena that occur once the system reaches its critical state. This paper investigates the stability of a shrink- ing cylindrical domain in a tube configuration during unload- ing. The energetics and thermodynamic driving force of the cylindrical domain are quantified by using an elastic inclu- sion model. It is demonstrated that the two domain fronts ex- hibit strong interaction when they come close to each other, which brings a peak in the total energy and a sign change in the thermodynamic driving force. It is proved that such domain front interaction plays an important role in control- ling the stability of the domain and in the occurrence of stress jumps during domain vanishing. It is also shown that the pro- cess is governed by two nondimensional length scales （the normalized tube length and normalized wall-thickness） and that the length scale dependence of the critical domain length and stress jump for the domain vanishing can be quantified by the elastic inclusion model.
基金the financial support of Science Fund for International Cooperation Project(No.152102410014)the Education Department of Henan Province Foundation(14A430030)Research Foundation of Zhengzhou City(131PPTGG-409-3)
文摘Al2 O3 - SiC - SiAION composite specimens have been prepared using fused alumina, ultra fine α-Al2O3, Si and Al powders as starting materials and liquid phenol formaldehyde resin as binder and firing at 1 500 ℃ for 3 h in carbon embedded condition. Thermo-mechanical properties of Al2 O3 - SiC - SiAlON composites have been studied. The results show ： （ 1 ） Al2 O3 - SiC - SiAION composites can be prepared and sintered at 1 500 ℃ under carbon embedded condition. When Si/Al ratio is 8/0 and 7/1, the prepared composite is Al2O3 - SiC - O＇ -SiAlON; when Si/Al ratio is 5/3 and 3/5, the pre- pared composite is Al2 O3 - SiC - β-SiAION. （ 2 ） The composites possess high temperature strength properties. Hot modulus of rupture at 1 400 ℃ is 10 - 30 MPa. They are in elastic range up to 1 000 ℃, after which plastic deformation is observed; even at 1 400 ℃, amount of deformation is relatively low. （3） The com- posites possess good thermal shock resistance, their resid- ual strength ratio （AT = 1 100 ℃ ） is 65% - 80%. （4） The marked improvement in thermo-mechanical properties of Al2O3 - SiC - SiAlON composites may be at- tributed to the in-situ formation of SiC, SiAlON and AIN, the fibrous SiC, columnar SiAlON and tabular-like AlN fill in the corundum skeleton structure creating strengthening and toughening effects.
文摘Rocks are composed of mineral particles and micropores between mineral which has a great influence on the mechanical properties of rocks. In this paper, based on the theory of locked-in stress developed by academician Chen Zongji, the locked-in stress problem in underground rock is simulated by the thermal expansion of hard rubber particles. The pore inclusion in rock is assumed to be uniformly distributed spherical cavities. Using the thermal stress theory, the stress of rock with a spherical pore inclusion is equivalent to the thermal stress generated by the spherical hard rubber inclusion. The elastic theory formula of the temperature increment and the equivalent pore pressure of the spherical hard rubber inclusion is derived. The numerical simulation of the rock mass model with a spherical hard rubber inclusion is carried out and compared to the theoretical calculation results<span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> the results show that they are consistent. The method proposed by this paper for simulating stress distribution in rock by thermal stress is reasonable and feasible</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:zh-cn;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"="">;</span><span lang="EN-US" style="font-family:;" minion="" pro="" capt",serif;font-size:10pt;mso-fareast-font-family:宋体;mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa;mso-bidi-font-weight:bold;"=""> it has a positive meaning for further study of mechanic phenomenon of rock with micropore inclusion.</span>
文摘The objective of the present paper is to develop nonlinear finite element method models for predicting the weld-induced initial deflection and residual stress of plating in steel stiffened-plate structures. For this purpose, three-dimensional thermo-elastic-plastic finite element method computations are performed with varying plate thickness and weld bead length (leg length) in welded plate panels, the latter being associated with weld heat input. The finite element models are verified by a comparison with experimental database which was obtained by the authors in separate studies with full scale measurements. It is concluded that the nonlinear finite element method models developed in the present paper are very accurate in terms of predicting the weld-induced initial imperfections of steel stiffened plate structures. Details of the numerical computations together with test database are documented.
