Resistive switching characteristics of hafnium oxide are studied for possible nonvolatile memory device applications.The HfOx films with different oxygen contents are deposited by rf magnetron sputtering under differe...Resistive switching characteristics of hafnium oxide are studied for possible nonvolatile memory device applications.The HfOx films with different oxygen contents are deposited by rf magnetron sputtering under different O_(2) flow rates.The films are amorphous,and the stoichiometric of the film is improved by increasing the O_(2) flow rate.Current-voltage characteristics of the TiN/HfOx/ITO device are investigated with 1 mA compliance.The bipolar resistive switching behavior is observed for the TiN/HfOx/ITO structure,and the resistive switching mechanism of the TiN/HfOx/ITO structure is explained by trap-controlled space charge limit current conduction.展开更多
Hafnium oxide films are deposited on Si(100)substrates by means of rf magnetron sputtering.The interfacial structure is studied using high-resolution transmission electron microscopy(HRTEM)and x-ray photoelectron spec...Hafnium oxide films are deposited on Si(100)substrates by means of rf magnetron sputtering.The interfacial structure is studied using high-resolution transmission electron microscopy(HRTEM)and x-ray photoelectron spectroscopy(XPS),and the electrical properties of the Au/HfO_(2)/Si stack are analyzed by frequency−dependent capacitance-voltage(C–V–f)measurements.The amorphous interfacial layer between HfO_(2) and the Si substrate is observed by the HRTEM method.From the results of XPS,the interfacial layer comprises hafnium silicate and silicon oxide.For C–V–f measurements,the C–V plots show a peak at a low frequency and the change in frequency has effects on the intensity of the peak.As expected,rapid thermal annealing can passivate the interface states of the HfO_(2)/Si stack.展开更多
The structural,electronic and mechanical properties of cubic SrHfO_(3) under hydrostatic pressure up to 70 GPa are investigated using the first-principles density functional theory(DFT).The calculated lattice paramete...The structural,electronic and mechanical properties of cubic SrHfO_(3) under hydrostatic pressure up to 70 GPa are investigated using the first-principles density functional theory(DFT).The calculated lattice parameter,elastic constants and mechanical properties of cubic SrHfO_(3) at zero pressure are in good agreement with the available experimental data and other calculational values.As pressure increases,cubic SrHfO_(3) will change from an indirect band gap(Γ-R)compound to a direct band gap(Γ-Γ)compound.Charge densities reveal the coexistence of covalent bonding and ionic bonding in cubic SrHfO_(3).With the increase of pressure,both the covalent bonding(HfO)and ionic bonding(SrO)are strengthened.Cubic SrHfO_(3) is mechanically stable when pressure is lower than 55.1 GPa,whereas that is instable when pressure is higher than 55.1 GPa.With the increasing pressure,enthalpy,bulk modulus,shear modulus and Young's modulus increase,whereas the lattice parameter decreases.Moreover,cubic SrHfO_(3) under pressure has higher hardness and better ductility than that at zero pressure.展开更多
In order to enhance transmittance in the long-wavelength infrared range,the major parameters of periodic sub-wavelength structures(SWS)with square holes on zinc sulfide(ZnS)substrates are designed and analyzed for app...In order to enhance transmittance in the long-wavelength infrared range,the major parameters of periodic sub-wavelength structures(SWS)with square holes on zinc sulfide(ZnS)substrates are designed and analyzed for applications in normal incidence by using rigorous coupled-wave analysis(RCWA)and thin Hilm theory(TFT).Finally the optimal antireflective parameters are achieved.The structures on ZnS substrates are fabricated on the basis of the simulation results by photolithography technology and reactive ion etching technology.A substantial antireflection effect is observed over the wavelength band 8-12μm by a factor greater than 4.5.展开更多
Objective: To investigate the effects of Composition of Ophiopogon polysaccharide, Notoginseng total saponins and Rhizoma Coptidis alkaloids(CONR) on myocardial apoptosis of diabetic atherosclerosis(DA) rabbits Method...Objective: To investigate the effects of Composition of Ophiopogon polysaccharide, Notoginseng total saponins and Rhizoma Coptidis alkaloids(CONR) on myocardial apoptosis of diabetic atherosclerosis(DA) rabbits Methods: Sixty male New Zealand white rabbits were randomly divided into 6 groups [control group, model group, CONR high-dose group(450 mg/kg), CONR medium-dose group(150 mg/kg), CONR low-dose group(50 mg/kg), and simvastatin group] by using a completely random method, 10 in each group. DA model was established by intravenously injected alloxan combined with high-fat diet and abdominal aortic balloon injury. After mediation for 10 weeks, fasting blood glucose(FBG), glycosylated hemoglobin(GHB), glycosylated serum protein(GSP), fructoseamine(FRA), aldose reductase(AR), advanced glycation end products(AGEs) in serum were measured by enzyme linked immunosorbent assay(ELISA) method;the expression of receptor of AGEs(RAGE) in myocardial tissue were observed by immunohistochemical method;and p-Jun N-terminal kinase(p-JNK), caspase-3, B-cell lymphoma-2(bcl-2) protein expression in myocardial tissue were measured by Western blotting. The myocardial apoptosis was detected by Td T-mediated d UTPnick-end labeling(TUNEL) method, and apoptosis index(AI) was calculated. Results: Compared with the control group, serum FBG, GHB, GSP, FRA, AR, AGEs and the expression of myocardium RAGE, p-JNK, caspase-3 proteins, as well as apoptosis index(AI) were significantly increased and bcl-2 protein was significantly decreased in the model group(P<0.01). Compared with the model group, the levels of serum FBG, GHB, GSP, FRA and AR showed a significant decline in CONR high-and medium-dose groups(P<0.01). FBG and GHB showed a significant decline in CONR low-dose group(P<0.01). Compared with the model group, the expression of serum AGEs and myocardium RAGE, p-JNK and caspase-3 protein as well as AI were significantly decreased and bcl-2 protein was significantly up-regulated in all treatment groups(P<0.01);high-dose CONR had the most significant effect on abovementioned indices compared with other treatment groups(P<0.01). Middle-dose CONR had better effect on serum AGEs compared with the low-dose group(P<0.01);middle-dose CONR and simvastatin groups had better effect on the expression of caspase-3, bcl-2 protein, myocardium apoptosis compared with the CONR low-dose group(P<0.01). Conclusion: CONR may effectively inhibit myocardial apoptosis on DA rabbits by intervening AGEs-RAGE and JNK, caspase-3, and bcl-2 protein expressions.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 51202196the Northwestern Polytechnical University(NPU)Foundation for Fundamental Research(No JC201111)+1 种基金the Research Fund of the State Key Laboratory of Solidification Processing(NWPU)(No 58-TZ-2011)the 111 Project(No B08040).
文摘Resistive switching characteristics of hafnium oxide are studied for possible nonvolatile memory device applications.The HfOx films with different oxygen contents are deposited by rf magnetron sputtering under different O_(2) flow rates.The films are amorphous,and the stoichiometric of the film is improved by increasing the O_(2) flow rate.Current-voltage characteristics of the TiN/HfOx/ITO device are investigated with 1 mA compliance.The bipolar resistive switching behavior is observed for the TiN/HfOx/ITO structure,and the resistive switching mechanism of the TiN/HfOx/ITO structure is explained by trap-controlled space charge limit current conduction.
基金by the Northwestern Polytechnical University(NPU)Foundation for Fundamental Research under Grant No JC201111the Research Fund of the State Key Laboratory of Solidification Processing(NWPU)under Grant No 58-TZ-2011,and the 111 Project under Grant No B08040.
文摘Hafnium oxide films are deposited on Si(100)substrates by means of rf magnetron sputtering.The interfacial structure is studied using high-resolution transmission electron microscopy(HRTEM)and x-ray photoelectron spectroscopy(XPS),and the electrical properties of the Au/HfO_(2)/Si stack are analyzed by frequency−dependent capacitance-voltage(C–V–f)measurements.The amorphous interfacial layer between HfO_(2) and the Si substrate is observed by the HRTEM method.From the results of XPS,the interfacial layer comprises hafnium silicate and silicon oxide.For C–V–f measurements,the C–V plots show a peak at a low frequency and the change in frequency has effects on the intensity of the peak.As expected,rapid thermal annealing can passivate the interface states of the HfO_(2)/Si stack.
基金Supported by the Natural Science Foundation of China under Grant No 50902110the Natural Science Foundation of Shaannxi Province under Grant No 2012JM6012+1 种基金the 111 Project under Grant No B07040the Northwestern Polytechnical University Foundation for Fundamental Research under Grant No JC20110245.
文摘The structural,electronic and mechanical properties of cubic SrHfO_(3) under hydrostatic pressure up to 70 GPa are investigated using the first-principles density functional theory(DFT).The calculated lattice parameter,elastic constants and mechanical properties of cubic SrHfO_(3) at zero pressure are in good agreement with the available experimental data and other calculational values.As pressure increases,cubic SrHfO_(3) will change from an indirect band gap(Γ-R)compound to a direct band gap(Γ-Γ)compound.Charge densities reveal the coexistence of covalent bonding and ionic bonding in cubic SrHfO_(3).With the increase of pressure,both the covalent bonding(HfO)and ionic bonding(SrO)are strengthened.Cubic SrHfO_(3) is mechanically stable when pressure is lower than 55.1 GPa,whereas that is instable when pressure is higher than 55.1 GPa.With the increasing pressure,enthalpy,bulk modulus,shear modulus and Young's modulus increase,whereas the lattice parameter decreases.Moreover,cubic SrHfO_(3) under pressure has higher hardness and better ductility than that at zero pressure.
基金Supported by the Aviation Science Fund(No 2008ZE53043)the Research Fund of the State Key Laboratory of Solidification Processing(NWPU)(No 58-TZ-2011).
文摘In order to enhance transmittance in the long-wavelength infrared range,the major parameters of periodic sub-wavelength structures(SWS)with square holes on zinc sulfide(ZnS)substrates are designed and analyzed for applications in normal incidence by using rigorous coupled-wave analysis(RCWA)and thin Hilm theory(TFT).Finally the optimal antireflective parameters are achieved.The structures on ZnS substrates are fabricated on the basis of the simulation results by photolithography technology and reactive ion etching technology.A substantial antireflection effect is observed over the wavelength band 8-12μm by a factor greater than 4.5.
基金Supported by National Natural Science Foundation of China(No.81374026)。
文摘Objective: To investigate the effects of Composition of Ophiopogon polysaccharide, Notoginseng total saponins and Rhizoma Coptidis alkaloids(CONR) on myocardial apoptosis of diabetic atherosclerosis(DA) rabbits Methods: Sixty male New Zealand white rabbits were randomly divided into 6 groups [control group, model group, CONR high-dose group(450 mg/kg), CONR medium-dose group(150 mg/kg), CONR low-dose group(50 mg/kg), and simvastatin group] by using a completely random method, 10 in each group. DA model was established by intravenously injected alloxan combined with high-fat diet and abdominal aortic balloon injury. After mediation for 10 weeks, fasting blood glucose(FBG), glycosylated hemoglobin(GHB), glycosylated serum protein(GSP), fructoseamine(FRA), aldose reductase(AR), advanced glycation end products(AGEs) in serum were measured by enzyme linked immunosorbent assay(ELISA) method;the expression of receptor of AGEs(RAGE) in myocardial tissue were observed by immunohistochemical method;and p-Jun N-terminal kinase(p-JNK), caspase-3, B-cell lymphoma-2(bcl-2) protein expression in myocardial tissue were measured by Western blotting. The myocardial apoptosis was detected by Td T-mediated d UTPnick-end labeling(TUNEL) method, and apoptosis index(AI) was calculated. Results: Compared with the control group, serum FBG, GHB, GSP, FRA, AR, AGEs and the expression of myocardium RAGE, p-JNK, caspase-3 proteins, as well as apoptosis index(AI) were significantly increased and bcl-2 protein was significantly decreased in the model group(P<0.01). Compared with the model group, the levels of serum FBG, GHB, GSP, FRA and AR showed a significant decline in CONR high-and medium-dose groups(P<0.01). FBG and GHB showed a significant decline in CONR low-dose group(P<0.01). Compared with the model group, the expression of serum AGEs and myocardium RAGE, p-JNK and caspase-3 protein as well as AI were significantly decreased and bcl-2 protein was significantly up-regulated in all treatment groups(P<0.01);high-dose CONR had the most significant effect on abovementioned indices compared with other treatment groups(P<0.01). Middle-dose CONR had better effect on serum AGEs compared with the low-dose group(P<0.01);middle-dose CONR and simvastatin groups had better effect on the expression of caspase-3, bcl-2 protein, myocardium apoptosis compared with the CONR low-dose group(P<0.01). Conclusion: CONR may effectively inhibit myocardial apoptosis on DA rabbits by intervening AGEs-RAGE and JNK, caspase-3, and bcl-2 protein expressions.
