The oxidizing behavior of Si-containing steel was investigated in an O2 and N2 binary-component gas with oxygen contents ranging between 0.5 vol% and 4.0 vol% under anisothermal-oxidation conditions. A simultaneous th...The oxidizing behavior of Si-containing steel was investigated in an O2 and N2 binary-component gas with oxygen contents ranging between 0.5 vol% and 4.0 vol% under anisothermal-oxidation conditions. A simultaneous thermal analyzer was employed to simulate the heating process of Si-containing steel in industrial reheating furnaces. The oxidation gas mixtures were introduced from the commencement of heating. The results show that the oxidizing rate remains constant in the isothermal holding process at high temperatures; therefore, the mass change versus time presents a linear law. A linear relation also exists between the oxidizing rate and the oxygen content. Using the linear regression equation, the oxidation rate at different oxygen contents can be predicted. In addition, the relationship between the total mass gain and the oxygen content is linear; thus, the total mass gain at oxygen contents between 0.5 vol%–4.0 vol% can be determined. These results enrich the theoretical studies of the oxidation process in Si-containing steels.展开更多
Heat as a stressor of poultry has been studied extensively for many decades; it affects poultry production on a worldwide basis and has significant impact on well-being and production. More recently, the involvement o...Heat as a stressor of poultry has been studied extensively for many decades; it affects poultry production on a worldwide basis and has significant impact on well-being and production. More recently, the involvement of heat stress in inducing oxidative stress has received much interest. Oxidative stress is defined as the presence of reactive species in excess of the available antioxidant capacity of animal cells. Reactive species can modify several biologically cellular macromolecules and can interfere with cell signaling pathways. Furthermore, during the last decade, there has been an ever-increasing interest in the use of a wide array of natural feed-delivered phytochemicals that have potential antioxidant properties for poultry. In light of this, the current review aims to(1) summarize the mechanisms through which heat stress triggers excessive superoxide radical production in the mitochondrion and progresses into oxidative stress,(2) illustrate that this pathophysiology is dependent on the intensity and duration of heat stress,(3) present different nutritional strategies for mitigation of mitochondrial dysfunction, with particular focus on antioxidant phytochemicals.Oxidative stress that occurs with heat exposure can be manifest in all parts of the body; however, mitochondrial dysfunction underlies oxidative stress. In the initial phase of acute heat stress, mitochondrial substrate oxidation and electron transport chain activity are increased resulting in excessive superoxide production. During the later stage of acute heat stress, down-regulation of avian uncoupling protein worsens the oxidative stress situation causing mitochondrial dysfunction and tissue damage. Typically, antioxidant enzyme activities are upregulated. Chronic heat stress, however, leads to downsizing of mitochondrial metabolic oxidative capacity, up-regulation of avian uncoupling protein, a clear alteration in the pattern of antioxidant enzyme activities, and depletion of antioxidant reserves.Some phytochemicals, such as various types of flavonoids and related compounds, were shown to be beneficial in chronic heat-stressed poultry, but were less or not effective in non-heat-stressed counterparts. This supports the contention that antioxidant phytochemicals have potential under challenging conditions. Though substantial progress has been made in our understanding of the association between heat stress and oxidative stress, the means by which phytochemicals can alleviate oxidative stress have been sparsely explored.展开更多
A nanostructured ternary coating of Ti/(Ru + Ti + Ce)O2 was prepared by the conventional electrodeposition on the titanium substrate as the cathode with different numbers of coating layers. The main objective of t...A nanostructured ternary coating of Ti/(Ru + Ti + Ce)O2 was prepared by the conventional electrodeposition on the titanium substrate as the cathode with different numbers of coating layers. The main objective of this work was to study nanostructured coatings of ceramic materials. For this purpose, the amount of precursor materials in the electrolyte was a variable parameter. Furthermore, the salt of TiCl4/RuCl3·xH2 O/Ce(NO3)3·6 H2 O with different amounts, hydrogen peroxide, methanol, and distilled water were used as an aqueousunaqueous bath. In addition, the coated samples were put to heat at 300, 450, 650, and 850℃ in an electric furnace for1 h. The crystalline phase of the coating was characterized by X-ray diffraction(XRD). The chemical composition and microstructure of the coating were studied using energydispersive spectroscopy(EDS) and scanning electron microscopy analysis(SEM). Moreover, the electrochemical measurement of Ti/(Ru + Ti + Ce)O2 coatings was carried out. Results show that with the increase in the number of coating layers, the quality of morphology is improved.Then, the best quality of coatings is obtained at six layers on the titanium substrate with electrolyte including TiO2/RuO2/CeO2 with the molar ratio of 70:5:25 after heat treatment at 450 ℃ for 1 h. Besides,with the increase in Ce02 content from 5 wt% to 25 wt% and the number of coating layers, higher thickness of about(20.0±0.1) μm and minimum over potential for chlorine evolution were obtained.展开更多
NdFeCo magnetic powder was prepared by the process of smelting, high-energy ball milling and oxidation heat treating. The effects of oxidation heat treatment and Co content on phase composition and microwave absorbing...NdFeCo magnetic powder was prepared by the process of smelting, high-energy ball milling and oxidation heat treating. The effects of oxidation heat treatment and Co content on phase composition and microwave absorbing properties of NdFeCo magnetic powder were investigated by an X-ray diffractometer (XRD) and vector network analyzer. The minimum reflectivity of Nd23.25Fe36.75Co40 powder before oxidation heat treatment was 4.2 dB, and that of oxidized powder decreased to -14.0 dB. The microwave absorbing properties of NdFeCo magnetic powder could be improved effectively by oxidation heat treatment. With the increase of Co content, the Fe2O3 reduced and the Nd2O3 increased; Fe3CO7 phase appeared when the content of Co increased to 40% (mass ratio); the absorption peak was found to move towards lower frequency region first, and then it moved towards a higher frequency region. Nd23.25Fe06.75Co10 powder had better comprehensive properties in absorbing microwave in the frequency band of 3-13 GHz. The value of minimum reflectivity and absorption peak frequency, when the coating thickness (d) was 1.8 mm, were -19.7 dB and 4.8 GHz, respectively.展开更多
To examine the inhibition of nitric oxide (NO) synthesis during ischemi c preconditioning (IP) upon the induction of heat shock protein 72 (HSP72) and the size limiting effect of the second window of protection on ...To examine the inhibition of nitric oxide (NO) synthesis during ischemi c preconditioning (IP) upon the induction of heat shock protein 72 (HSP72) and the size limiting effect of the second window of protection on infarction Methods Rabbits were subjected to either 4 cycles of 5 min long coronary artery occl usion separated by 10 min of reperfusion, or a sham operation During this procedure, we administered 10 mg/kg of N G nitro L arginine methyl ester (L N AME, an inhibitor of NO synthase) intravenously 5 min before IP followed by its continuous infusion (1 5 mg/kg/min) Twenty four hours after IP or the sh am operation, the hearts were rapidly excised for assay of HSP72 expression or w ere subjected to 30 min of coronary artery occlusion followed by 120 min of rep erfusion, at which point infarct size (IS) was measured Results Twenty four hours after IP or the sham operation, there was no difference in he art rate or mean arterial pressure between the groups Immunoblotting revealed an increase in HSP72 protein levels in the IP group, which was blocked by L NAM E IS in the IP rabbits was reduced compared with controls (29 8±3 7% vs 50 8±4 3 %, P <0 01) IS in the IP rabbits was elevated as a result o f L NAME treatment (46 0±5 1%) Administration of L arginine reversed the effects of L NAME on the induction of HSP72 and IS (33 5±4 0%) The intrave nous administration of S nitroso N acetylpenicillamine (an NO donor, 15 μg /kg/min) over 20 min increased the induction of HSP72 and reduced IS (31 3±5 7%, P <0 01 vs control) 24 h later Conclusion These findings suggest that NO may be involved in the induction of HSP72 and the opening of the second window of protection of IP展开更多
基金financially supported by the National Natural Science Foundation of China(No.51274154)The Major Projects of Technology Innovation of Hubei Province,China(No.2017AAA116)the Special Fund of Wuhan University of Science and Technology for Master Student’s Short-Term Studying Abroad
文摘The oxidizing behavior of Si-containing steel was investigated in an O2 and N2 binary-component gas with oxygen contents ranging between 0.5 vol% and 4.0 vol% under anisothermal-oxidation conditions. A simultaneous thermal analyzer was employed to simulate the heating process of Si-containing steel in industrial reheating furnaces. The oxidation gas mixtures were introduced from the commencement of heating. The results show that the oxidizing rate remains constant in the isothermal holding process at high temperatures; therefore, the mass change versus time presents a linear law. A linear relation also exists between the oxidizing rate and the oxygen content. Using the linear regression equation, the oxidation rate at different oxygen contents can be predicted. In addition, the relationship between the total mass gain and the oxygen content is linear; thus, the total mass gain at oxygen contents between 0.5 vol%–4.0 vol% can be determined. These results enrich the theoretical studies of the oxidation process in Si-containing steels.
基金the Special Research Fund(BOF)of Ghent University(Belgium)for the financial support of Abdol ah Akbarian(grant number 01SF2711)
文摘Heat as a stressor of poultry has been studied extensively for many decades; it affects poultry production on a worldwide basis and has significant impact on well-being and production. More recently, the involvement of heat stress in inducing oxidative stress has received much interest. Oxidative stress is defined as the presence of reactive species in excess of the available antioxidant capacity of animal cells. Reactive species can modify several biologically cellular macromolecules and can interfere with cell signaling pathways. Furthermore, during the last decade, there has been an ever-increasing interest in the use of a wide array of natural feed-delivered phytochemicals that have potential antioxidant properties for poultry. In light of this, the current review aims to(1) summarize the mechanisms through which heat stress triggers excessive superoxide radical production in the mitochondrion and progresses into oxidative stress,(2) illustrate that this pathophysiology is dependent on the intensity and duration of heat stress,(3) present different nutritional strategies for mitigation of mitochondrial dysfunction, with particular focus on antioxidant phytochemicals.Oxidative stress that occurs with heat exposure can be manifest in all parts of the body; however, mitochondrial dysfunction underlies oxidative stress. In the initial phase of acute heat stress, mitochondrial substrate oxidation and electron transport chain activity are increased resulting in excessive superoxide production. During the later stage of acute heat stress, down-regulation of avian uncoupling protein worsens the oxidative stress situation causing mitochondrial dysfunction and tissue damage. Typically, antioxidant enzyme activities are upregulated. Chronic heat stress, however, leads to downsizing of mitochondrial metabolic oxidative capacity, up-regulation of avian uncoupling protein, a clear alteration in the pattern of antioxidant enzyme activities, and depletion of antioxidant reserves.Some phytochemicals, such as various types of flavonoids and related compounds, were shown to be beneficial in chronic heat-stressed poultry, but were less or not effective in non-heat-stressed counterparts. This supports the contention that antioxidant phytochemicals have potential under challenging conditions. Though substantial progress has been made in our understanding of the association between heat stress and oxidative stress, the means by which phytochemicals can alleviate oxidative stress have been sparsely explored.
基金financially supported by the Semnan University Foundation of Iran
文摘A nanostructured ternary coating of Ti/(Ru + Ti + Ce)O2 was prepared by the conventional electrodeposition on the titanium substrate as the cathode with different numbers of coating layers. The main objective of this work was to study nanostructured coatings of ceramic materials. For this purpose, the amount of precursor materials in the electrolyte was a variable parameter. Furthermore, the salt of TiCl4/RuCl3·xH2 O/Ce(NO3)3·6 H2 O with different amounts, hydrogen peroxide, methanol, and distilled water were used as an aqueousunaqueous bath. In addition, the coated samples were put to heat at 300, 450, 650, and 850℃ in an electric furnace for1 h. The crystalline phase of the coating was characterized by X-ray diffraction(XRD). The chemical composition and microstructure of the coating were studied using energydispersive spectroscopy(EDS) and scanning electron microscopy analysis(SEM). Moreover, the electrochemical measurement of Ti/(Ru + Ti + Ce)O2 coatings was carried out. Results show that with the increase in the number of coating layers, the quality of morphology is improved.Then, the best quality of coatings is obtained at six layers on the titanium substrate with electrolyte including TiO2/RuO2/CeO2 with the molar ratio of 70:5:25 after heat treatment at 450 ℃ for 1 h. Besides,with the increase in Ce02 content from 5 wt% to 25 wt% and the number of coating layers, higher thickness of about(20.0±0.1) μm and minimum over potential for chlorine evolution were obtained.
基金National Natural Science Foundation of China(50961005)Natural Science Foundation of Guangxi(0991002Z)Innovation Project of Guangxi Graduate Education(2011105950805M38)
文摘NdFeCo magnetic powder was prepared by the process of smelting, high-energy ball milling and oxidation heat treating. The effects of oxidation heat treatment and Co content on phase composition and microwave absorbing properties of NdFeCo magnetic powder were investigated by an X-ray diffractometer (XRD) and vector network analyzer. The minimum reflectivity of Nd23.25Fe36.75Co40 powder before oxidation heat treatment was 4.2 dB, and that of oxidized powder decreased to -14.0 dB. The microwave absorbing properties of NdFeCo magnetic powder could be improved effectively by oxidation heat treatment. With the increase of Co content, the Fe2O3 reduced and the Nd2O3 increased; Fe3CO7 phase appeared when the content of Co increased to 40% (mass ratio); the absorption peak was found to move towards lower frequency region first, and then it moved towards a higher frequency region. Nd23.25Fe06.75Co10 powder had better comprehensive properties in absorbing microwave in the frequency band of 3-13 GHz. The value of minimum reflectivity and absorption peak frequency, when the coating thickness (d) was 1.8 mm, were -19.7 dB and 4.8 GHz, respectively.
文摘To examine the inhibition of nitric oxide (NO) synthesis during ischemi c preconditioning (IP) upon the induction of heat shock protein 72 (HSP72) and the size limiting effect of the second window of protection on infarction Methods Rabbits were subjected to either 4 cycles of 5 min long coronary artery occl usion separated by 10 min of reperfusion, or a sham operation During this procedure, we administered 10 mg/kg of N G nitro L arginine methyl ester (L N AME, an inhibitor of NO synthase) intravenously 5 min before IP followed by its continuous infusion (1 5 mg/kg/min) Twenty four hours after IP or the sh am operation, the hearts were rapidly excised for assay of HSP72 expression or w ere subjected to 30 min of coronary artery occlusion followed by 120 min of rep erfusion, at which point infarct size (IS) was measured Results Twenty four hours after IP or the sham operation, there was no difference in he art rate or mean arterial pressure between the groups Immunoblotting revealed an increase in HSP72 protein levels in the IP group, which was blocked by L NAM E IS in the IP rabbits was reduced compared with controls (29 8±3 7% vs 50 8±4 3 %, P <0 01) IS in the IP rabbits was elevated as a result o f L NAME treatment (46 0±5 1%) Administration of L arginine reversed the effects of L NAME on the induction of HSP72 and IS (33 5±4 0%) The intrave nous administration of S nitroso N acetylpenicillamine (an NO donor, 15 μg /kg/min) over 20 min increased the induction of HSP72 and reduced IS (31 3±5 7%, P <0 01 vs control) 24 h later Conclusion These findings suggest that NO may be involved in the induction of HSP72 and the opening of the second window of protection of IP