Aim To improve the thermostability of vane absorbers while designing and manu- facturing. Methods Having considered the structural features of vane absorbers, measures that could reduce the force decay ratio of vane ...Aim To improve the thermostability of vane absorbers while designing and manu- facturing. Methods Having considered the structural features of vane absorbers, measures that could reduce the force decay ratio of vane absorbers were discussed. A kind of practical auto temperature compensation apparatus, whose theoretical basis had been discussed, was designed. Results Compared to the prototype vane absorber, this kind of apparatus could decrease force decay ratio sharply. Thus, the thermostability of vane absorbers was improved greatly The accuracy of theoretical analysis and the effectiveness and feasibility of the apparatus was proved by actual testing Conclusion changing vane absorber's configuration, its performance is improved.展开更多
Polyimide matrix composites interpenetrated with foamed copper were prepared via pressure impregnation and vacuum immersion to focus on their thermostability, mechanical and tribological behaviors as sliding electrica...Polyimide matrix composites interpenetrated with foamed copper were prepared via pressure impregnation and vacuum immersion to focus on their thermostability, mechanical and tribological behaviors as sliding electrical contact materials. The results show that the interpenetrating phase composites（IPC） are very heat-resistant and exhibit higher hardness as well as bending strength, when compared with homologous polyimide matrix composites without foamed copper. Sliding electrical contact property of the materials is also remarkably improved, from the point of contact voltage drops. Moreover, it is believed that fatigue wear is the main mechanism involved, along with slight abrasive wear and oxidation wear. The better abrasive resistance of the IPC under different testing conditions was detected, which was mainly attributed to the successful hybrid of foamed copper and polyimide.展开更多
Of all reported polymorphs of clopidogrel hydrogen sulfate, Form Ⅰ is difficult to produce and store owing to its poor thermostability. It is reported that Form Ⅰ can spontaneously transform into Form Ⅱ at high tem...Of all reported polymorphs of clopidogrel hydrogen sulfate, Form Ⅰ is difficult to produce and store owing to its poor thermostability. It is reported that Form Ⅰ can spontaneously transform into Form Ⅱ at high temperature and humidity. In this study, high purity Form I of clopidogrel hydrogen sulfate with good thermodynamic stability was prepared by a centrifugation-assisted recrystallization technology. The resultant product was characterized by powder X-ray diffraction （PXRD）, differential scanning calorimetry （DSC） and scanning electron microscope （SEM）. The results showed that the crystallinity and crystallite size of the Form Ⅰ prepared by the centrifugation-assisted recrystallization method were larger than those obtained by conventional anti-solvent recrystallization methods. Long-term thermostability testing demonstrated that the improved product can keep stable crystal structure even at high temperature and humidity.展开更多
Owing to the adaptability to large scale processing,excellent composition control and film uniformity,the metal-organic chemical vapor deposition（MOCVD） technique is a promising process for high-temperature supercon...Owing to the adaptability to large scale processing,excellent composition control and film uniformity,the metal-organic chemical vapor deposition（MOCVD） technique is a promising process for high-temperature superconductor YBa;Cu;O;（YBCO） preparation.In this technique,the evaporation characteristics and thermostability of adopted precursors in whole process will decide the quality and reproducible results of YBCO film.In the present report,bis（2,2,6,6-tetramethyl-3,5-heptanedionato）copper（II）(Cu（TMHD）;) was synthesized by the interaction of copper acetate hydrate with TMHD in methanol solution,and its structure was identified by FTIR,1 H NMR,and EI-MS spectroscopy.Subsequently,thermal property and the kinetics of decomposition were systematically investigated by nonisothermal thermogravimetric analysis methods（TGA） at different heating rates in streams of N;,and the average apparent activation energy of evaporation process was evaluated by the Ozawa,Kissinger,and Friedman methods.The possible conversion function was estimated through the Coats-Redfern method to characterize the evaporation patterns and followed a phase boundary reaction mechanism by the contracting area equation with average activation energy of 85.1 kJ·mol;.展开更多
The magnetic properties, structure defects of electrodeposited Fe-Ni-P alloys with various compositions and the thermostability at amorphous state have been studied by DSC, positron annihilation and electronic integra...The magnetic properties, structure defects of electrodeposited Fe-Ni-P alloys with various compositions and the thermostability at amorphous state have been studied by DSC, positron annihilation and electronic integrating instrument methods. The results show that the thermostability of amorphous Fe-Ni-P alloys increases with Fe content. Emergence and recrystallization of stable phases defer as the P content of the coating increases. The minimum H-c, B-r and P-h occur at 9.4 P (wt pet) content. Maximum H-c, B-r and P-h occur at the weight ratio of Fe to Ni equaling to 1/9.展开更多
In order to improve the thermostability of β- 1,3-1,4-glucanase, evolutionary molecular engineering was used to evolve the β-1,3-1,4-glucanase from Bacillus subtilis ZJF-1A5. The process involves random mutation by ...In order to improve the thermostability of β- 1,3-1,4-glucanase, evolutionary molecular engineering was used to evolve the β-1,3-1,4-glucanase from Bacillus subtilis ZJF-1A5. The process involves random mutation by error-prone PCR and DNA shuffling followed by screening on the filter-based assay. Two mutants, EGsl and EGs2, were found to have four and five amino acid substitutions, respectively. These substitutions resulted in an increase in melting temperature from Tm=62.5℃ for the wild-type enzyme to Tm=65.5℃ for the mutant EGsl and 67.5℃ for the mutant EGs2. However, the two mutated enzymes had opposite approaches to produce reducing sugar from lichenin with either much higher （28%） for the former or much lower （21.6%） for the latter in comparison with their parental enzymes. The results demonstrate that directed evolution is an effective approach to improve the thermostability of a mesophilic enzyme.展开更多
13-Amylase activity （BAA） and thermostability （BAT） are important traits for malt quality. In this study, 138 Tibetan annual wild barley accessions and 20 cultivated genotypes differing in BAh, were planted and an...13-Amylase activity （BAA） and thermostability （BAT） are important traits for malt quality. In this study, 138 Tibetan annual wild barley accessions and 20 cultivated genotypes differing in BAh, were planted and analyzed in 2009 and 2012. Significant differences were detected among genotypes in BAA and BAT. The cultivated genotypes had a mean BAA of 1137.6 U/g and a range of from 602.1 to 1407.5 U/g, while the wild accessions had a mean of 1517.9 U/g and a range of from 829.7 to 2310.0 U/g. The cultivated genotypes had a mean relative residual 13-amylase activity （RRBAA） of 61.6% and a range of from 22.2% to 82.3%, while the wild barleys had a mean of 57.8% and a range of from 21.9% to 96.1%. Moreover, there was a significant difference among genotypes in the response of RRBAA to the temperature and duration of heat treatment. The wild barleys had wider variation in BAA and BAT than cultivated genotvDes.展开更多
An environmentally friendly method for the synthesis of LiMnPO_(4)/C anode material for lithium-ion batteries by solvothermal method is introduced.The modification of the morphology of this precursor is altered by cha...An environmentally friendly method for the synthesis of LiMnPO_(4)/C anode material for lithium-ion batteries by solvothermal method is introduced.The modification of the morphology of this precursor is altered by changing the ratio of the conditioning solvent(water-ethylene glycol solution)and the order of material addition.Ethylene glycol(EG)exerts a considerable influence on synthesizing LiMnPO_(4)/C flake-like nanocrystal,which benefits the extraction/insertion reaction of lithium ions and improves the electrochemical activity and electrochemical performance of LiMnPO_(4)/C material.When the solvent composition is H_(2)O:EG=1:3,exhibiting exceptional charge/discharge performance and rate capability,the specific discharge capacities are 155.8,153.7,148.8,141.4,129.5,and 112.6 mAh g^(−1) at the 0.1,0.2,0.5,1,2,and 5 C rates,respectively.When the charge-discharge rate returns to 0.1 C,the LiMnPO_(4)/C material shows a reversible discharge specific capacity of 153.7 mAh g^(−1).Differential scanning calorimetry(DSC)tests verify that the thermodynamic stability of the prepared LiMnPO_(4)/C(LMP)and commercial LiFePO_(4)(LFP)materials is better than that of commercial nickel-cobalt-aluminum(NCA)ternary materials.These prepared LiMnPO_(4)/C composites have high electrochemical capacity and cycle stability.展开更多
To study the thermostability of Nattokinase（subtilisin NAT,NK）,three double mutant plasmids（pET-28a-NKG61C/S98C,pET-28a-NKT22C/S87C,pET-28a-NKS24C/S87C）were constructed by site-directed mutagenesis.Target enzymes ...To study the thermostability of Nattokinase（subtilisin NAT,NK）,three double mutant plasmids（pET-28a-NKG61C/S98C,pET-28a-NKT22C/S87C,pET-28a-NKS24C/S87C）were constructed by site-directed mutagenesis.Target enzymes were detected using SDS-PAGE and disulfide bond formation was detected using Western blotting analysis.Thermostability was tested by rates of inactivation at certain temperature.The results showed that disulfide bond was not formed within two cysteines and the thermostability of three double mutants was not increased compared with the wild-type NK.The thermostability of NK performed in Ca2＋was stronger than in ethylenediaminetetraacetic acid（EDTA）.But when the temperature reached 62℃,the enzymes rapidly denatured and inactivated even in the presence of Ca2＋.Although the thermostability of mutants was not increased,this study shows a tendency of improving thermostability of NK in protein engineering.展开更多
A new phase MgYZn4 in Mg-Zn-Y alloy was studied using aberration-corrected scanning-transmission electron microscopy and first-principles calculations. Nanometer-sized MgYZn4 precipitates were formed through ordered s...A new phase MgYZn4 in Mg-Zn-Y alloy was studied using aberration-corrected scanning-transmission electron microscopy and first-principles calculations. Nanometer-sized MgYZn4 precipitates were formed through ordered substitutions of Y with 50% Mg atoms in MgZn2. MgYZn4 has an orthorhombic structure with a space group of Pmnn, and lattice parameters a =5.2965∧, b =9.4886∧, and c =8.5966 ∧. Importantly, both size and structure of MgYZn4 are stable at 625 K for 5 h, showing higher thermostability than MgZn2, which should be important for applications at elevated temperatures. The enhanced thermostability of MgYZn4 is attributed to the lower formation energy and bonding enhancement due to Y substitution.展开更多
The metal-organic chemical vapor deposition （MOCVD） technique is a promising process for high-tem- perature superconductor YBa2Cu307_6（YBCO） preparation. In this technique, it is a challenge to obtain barium precu...The metal-organic chemical vapor deposition （MOCVD） technique is a promising process for high-tem- perature superconductor YBa2Cu307_6（YBCO） preparation. In this technique, it is a challenge to obtain barium precursors with high volatility. In addition, the purity, evaporation characteristics, and thermostability of adopted precursors in whole process will decide the quality and reproducible results of YBCO film. In the present report, bis（2,2,6,6-tetramethyl- 3,5-heptanedionato）barium（II） （Ba（TMHD）2） was synthe- sized, and its structure was identified by PTIR, 1H NMR, 13C NMR, and ESI-MS spectroscopy. Subsequently, the thermal properties and the kinetics of decomposition were systemati- cally investigated by nonisothermal thermogravimetric anal- ysis methods. Based on the average apparent activation energy evaluated by the Ozawa, Kissinger, and Friedman methods, the volatilization process was discussed, and all results show that Ba（TMHD）2 is unstable and highly sensitive to the change of temperature during the whole evaporation process. There- fore, it is very important to choose suitable volatilization technology and conditions for avoiding Ba（TMHD）2 break- down （or thermal aging） during MOCVD process. Subse- quently, the possible conversion function is estimated through the Coats-Redfern method to characterize the evaporation patterns and follows a phase boundary reaction mechanism by the contracting surface equation with average activation energy of 118.7 kJ.mo1-1.展开更多
This study aimed to improve the thermostability of arylsulfatase from Pseudoalteromonas carrageenovora. A library of P. carrageenovora arylsulfatase mutants was constructed by introducing random mutagenesis using erro...This study aimed to improve the thermostability of arylsulfatase from Pseudoalteromonas carrageenovora. A library of P. carrageenovora arylsulfatase mutants was constructed by introducing random mutagenesis using error-prone PCR. After screening, two mutants of H260L and D84A/H260L showed enhanced thermal stability than the wild-type predecessor (WT). Site-directed mutagenesis demonstrated that only amino acid residue at Position 260 plays an important role in the thermostability of P. carrageenovora arylsulfatase. Thermal inactivation analysis showed that the half-life (t1/2) values at 55°C for H260L, H260I, H260Q, H260F and H260R were 40.6, 48.4, 30.9, 29.1 and 34.5 min, respectively, while that of WT was 9.1 min. Structure modeling demonstrated that the additional hydrogen bonds and/or optimization of surface charge-charge interactions could be responsible for the increased thermostability imparted by H260L, H260I, H260Q, H260F and H260R.展开更多
The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophi...The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophilic bacterium Acidithiobacillus sp. SM-1 （SORsB）. The optimal temperatures for catalyzing sulfur oxidation were 80 ℃ （SORAT）, 85 ℃ （SORsT）, and 70 ℃ （SORsB）, respectively. The half-lives of the three SORs at their optimal catalytic conditions were 100 min （SORAT）, 58 min （SORsT）, and 37 min （SORsB）. In order to reveal the structural basis of the thermostability of these SORs, three-dimensional structural models of them were generated by homology modeling using the previously reported high-resolution X-ray structure of SORAA （from Acidianus ambivalens） as a template. The results suggest that thermostability was dependent on： （a） high number of the charged amino acid glutamic acid and the flexible amino acid proline, （b） low number of the therraolabile amino acid glutamine, （c） increased number of ion pairs, （d） decreased ratio of hydrophobie accessible solvent surface area （ASA） to charged ASA, and （e） increased volumes of the cavity. The number of cavities and the number of hydrogen bonds did not signifieantly affect the thermostability of SORs, whereas the cavity volumes increased as the thermal stability increased.展开更多
The influence of thermo cycle times under variant loads and environment temperatures on the properties of Cu-16.4Zn-4Al (Re) SMA component was studied by thermostability experiments on Cu-16.4Zn-4Al SMA with the compo...The influence of thermo cycle times under variant loads and environment temperatures on the properties of Cu-16.4Zn-4Al (Re) SMA component was studied by thermostability experiments on Cu-16.4Zn-4Al SMA with the composition containing corium Re. Tangent rule was applied to determine the transformation temperature from displacement-temperature loop plot by computer in each thermal-cold cycle. The results is as follows the transformation temperature increases and shape memory property decrease with increasing load, which leads the action temperature of component to be abnormal, and the memory property decreases after overheating aging, and the memory property decreases with increasing cycle times, while the decreasing is not obvious and the recovery ratio is higher than 90% in one thousand times. It is due to the addition of corium Re which has the function of grain refinement. Therefore, it is necessary to avoid overloading and overheating in the application of such component. Thus, a kind of thermo valve that works at normal pressure and in the water as working substance was designed to replace complicate original electromechanical system.展开更多
Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites ...Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed(about 600 oC), the cis- isomerism of bentonite is expected, while two peaks of de-hydroxylation(about 550 and 850 oC) are expected in the trans- one. In this overview, the bentonite structure, the water – bentonite interaction and the swelling behavior of bentonite in connection with the general technological properties of bentonite molding mixture are summarized. Further, various types of methods for determination of bentonite thermostability are discussed, including instrumental analytical methods as well as methods that employ evaluation of various technological properties of bentonite binders and/or bentonite molding mixtures.展开更多
The solid structures and thermostabilities of Cu-Fe-O and Cu-Fe-Ce-O supported on alumina were studied by XRD, ESR, Mossbauer and TPR techniques. The studies indicate that there are Fe2CuO4, CuO and alpha-Fe2O3 phases...The solid structures and thermostabilities of Cu-Fe-O and Cu-Fe-Ce-O supported on alumina were studied by XRD, ESR, Mossbauer and TPR techniques. The studies indicate that there are Fe2CuO4, CuO and alpha-Fe2O3 phases in Cu-Fe-O with the granula of less than 13 nm. With the catalyst pretreatment temperature rising, the crystallite of Fe2CuO4 in the catalysts grows up and that of CuO disappears gradually. The presence of Ce leads to the increase of Cu2+ concentration, inhibits the crystal growth of CuO and Fe2CuO4 in the catalyst except that of Fe2O3, and eliminates the difference for reductive reaction of oxygen in Fe-O and Cu-O. At 800 degrees C, the crystal growth of Fe2O3 in Cu-Fe-Ce-O is slower than that in Cu-Fe-O, i.e., CeO2 in Cu-Fe-Ce-O inhibits the growth of Fe2O3 phase effectively, and enhances the thermostability of catalysts so as to avoid the sintering of active elements in catalysts. CeO2 promotes the reducibility of catalysts at lower temperature.展开更多
The metal-organic chemical vapor deposition (MOCVD) technique is a promising process for high-temperature superconductor YBa2Cu3O7-δ(YBCO) preparation. In this technique, it is a challenge to obtain barium precursors...The metal-organic chemical vapor deposition (MOCVD) technique is a promising process for high-temperature superconductor YBa2Cu3O7-δ(YBCO) preparation. In this technique, it is a challenge to obtain barium precursors with high volatility. In addition, the purity, evaporation characteristics and thermostability of adopted precursors in the whole process would decide the quality and reproducible results of YBCO film. In the present report, the barium precursor containing 2,2,6,6-tetramethylheptane-3,5-dionate and tetraethylenepentamine ligands (Ba(TMHD)-tetraen) was synthesized and identified by FTIR, 1H NMR, 13C NMR and ESI-MS spectroscopy. Subsequently the thermal property and the kinetics of decomposition were systematically investigated by combining non-isothermal thermogravimetric analysis methods (TGA), Ozawa, Kissinger and Friedman methods. On the basis of the apparent activation energy of the evaporation process, the thermostability and evaporation characteristics of the precursors were discussed. All results show that Ba(TMHD)-tetraen has higher volatility than Ba(TMHD)2, but it is unstable and highly sensitive to the change of temperature during the whole evaporation process. Therefore, it is very important to choose suitable volatilization technology and conditions for avoiding Ba(TMHD)-tetraen breakdown (or thermal aging) during the MOCVD process.展开更多
A nanometer porphyrin trimer was firstly synthesized with 1 ,3-dibromopropane as a bridge-linked agent and the fluorescence property and thermostability were studied. The results show that the fluorescence property an...A nanometer porphyrin trimer was firstly synthesized with 1 ,3-dibromopropane as a bridge-linked agent and the fluorescence property and thermostability were studied. The results show that the fluorescence property and thermostability of the trimer are different from those of monoporphyrin. The effects of the molecule structure on the optical property and the thermostability were also studied in detail.展开更多
The metal-organic chemical vapor deposition （MOCVD） technique is a promising process for high temperature superconductor YBa2Cu3O7-δ （YBCO） preparation. In this technique, the purity, evaporation characteristics ...The metal-organic chemical vapor deposition （MOCVD） technique is a promising process for high temperature superconductor YBa2Cu3O7-δ （YBCO） preparation. In this technique, the purity, evaporation characteristics and thermostability of adopted precursors will de- cide the quality and reproducible results of YBCO film. In the present report, tris（2,2,6,6-tetramethyl-3,5-heptanedionato）yttrium（III） （Y（TMHD）3） was synthesized by the interaction of yttrium nitrate hydrate with TMHD in methanol solution, and its structure was identified by FTIR, 1H NMR, 13C NMR and EI-MS spectroscopy. Subsequently, the thermal property and the kinetics of decomposition were system- atically investigated by non-isothermal thermogravimetric analysis methods （TGA） at different heating rates in streams of N2, and the average apparent activation energy of evaporation process was evaluated by the Ozawa, Kissinger and Friedman methods. The possible conversion function was estimated through the Coats-Redfern method to characterize the evaporation patterns and followed a phase boundary reaction mechanism by the contracting area equation with average activation energy of 88.9 kJ/mol.展开更多
The glass formability of NiBSimelt and the thermostability of this metallic glass formedfrom the the melt can be enhanced by eliminating the heterogeneous catalystg. The purificationwas done by cyclical superheating m...The glass formability of NiBSimelt and the thermostability of this metallic glass formedfrom the the melt can be enhanced by eliminating the heterogeneous catalystg. The purificationwas done by cyclical superheating melt in special glasses and subsequently cyclicallysuperheating it in an electromagnetic levitation apparatus. The purified NiBSiamorphoussample sized up to 20 ~ I0 x 0.5 mm was prepared as four times the thickness of unpurifiedones.展开更多
文摘Aim To improve the thermostability of vane absorbers while designing and manu- facturing. Methods Having considered the structural features of vane absorbers, measures that could reduce the force decay ratio of vane absorbers were discussed. A kind of practical auto temperature compensation apparatus, whose theoretical basis had been discussed, was designed. Results Compared to the prototype vane absorber, this kind of apparatus could decrease force decay ratio sharply. Thus, the thermostability of vane absorbers was improved greatly The accuracy of theoretical analysis and the effectiveness and feasibility of the apparatus was proved by actual testing Conclusion changing vane absorber's configuration, its performance is improved.
文摘Polyimide matrix composites interpenetrated with foamed copper were prepared via pressure impregnation and vacuum immersion to focus on their thermostability, mechanical and tribological behaviors as sliding electrical contact materials. The results show that the interpenetrating phase composites（IPC） are very heat-resistant and exhibit higher hardness as well as bending strength, when compared with homologous polyimide matrix composites without foamed copper. Sliding electrical contact property of the materials is also remarkably improved, from the point of contact voltage drops. Moreover, it is believed that fatigue wear is the main mechanism involved, along with slight abrasive wear and oxidation wear. The better abrasive resistance of the IPC under different testing conditions was detected, which was mainly attributed to the successful hybrid of foamed copper and polyimide.
基金National Natural Science Foundation of China(Grant No.51403188)Zhejiang Provincial Natural Science Foundation of China(Grant No.LY13E030004)Research Fund for the Doctoral Program of Higher Education of China(Grant No.20123318120005)
文摘Of all reported polymorphs of clopidogrel hydrogen sulfate, Form Ⅰ is difficult to produce and store owing to its poor thermostability. It is reported that Form Ⅰ can spontaneously transform into Form Ⅱ at high temperature and humidity. In this study, high purity Form I of clopidogrel hydrogen sulfate with good thermodynamic stability was prepared by a centrifugation-assisted recrystallization technology. The resultant product was characterized by powder X-ray diffraction （PXRD）, differential scanning calorimetry （DSC） and scanning electron microscope （SEM）. The results showed that the crystallinity and crystallite size of the Form Ⅰ prepared by the centrifugation-assisted recrystallization method were larger than those obtained by conventional anti-solvent recrystallization methods. Long-term thermostability testing demonstrated that the improved product can keep stable crystal structure even at high temperature and humidity.
基金supported by the Major State Basic Research Development Program of China (973 Program) (No.2011CBA00105)the National Natural Science Foundation of China (Nos. 51002149 and 21101151)
文摘Owing to the adaptability to large scale processing,excellent composition control and film uniformity,the metal-organic chemical vapor deposition（MOCVD） technique is a promising process for high-temperature superconductor YBa;Cu;O;（YBCO） preparation.In this technique,the evaporation characteristics and thermostability of adopted precursors in whole process will decide the quality and reproducible results of YBCO film.In the present report,bis（2,2,6,6-tetramethyl-3,5-heptanedionato）copper（II）(Cu（TMHD）;) was synthesized by the interaction of copper acetate hydrate with TMHD in methanol solution,and its structure was identified by FTIR,1 H NMR,and EI-MS spectroscopy.Subsequently,thermal property and the kinetics of decomposition were systematically investigated by nonisothermal thermogravimetric analysis methods（TGA） at different heating rates in streams of N;,and the average apparent activation energy of evaporation process was evaluated by the Ozawa,Kissinger,and Friedman methods.The possible conversion function was estimated through the Coats-Redfern method to characterize the evaporation patterns and followed a phase boundary reaction mechanism by the contracting area equation with average activation energy of 85.1 kJ·mol;.
文摘The magnetic properties, structure defects of electrodeposited Fe-Ni-P alloys with various compositions and the thermostability at amorphous state have been studied by DSC, positron annihilation and electronic integrating instrument methods. The results show that the thermostability of amorphous Fe-Ni-P alloys increases with Fe content. Emergence and recrystallization of stable phases defer as the P content of the coating increases. The minimum H-c, B-r and P-h occur at 9.4 P (wt pet) content. Maximum H-c, B-r and P-h occur at the weight ratio of Fe to Ni equaling to 1/9.
基金Project supported by the National Natural Science Foundation of China (No. 20276064) and Natural Science Foundation of ZhejiangProvince (No. Z304076), China
文摘In order to improve the thermostability of β- 1,3-1,4-glucanase, evolutionary molecular engineering was used to evolve the β-1,3-1,4-glucanase from Bacillus subtilis ZJF-1A5. The process involves random mutation by error-prone PCR and DNA shuffling followed by screening on the filter-based assay. Two mutants, EGsl and EGs2, were found to have four and five amino acid substitutions, respectively. These substitutions resulted in an increase in melting temperature from Tm=62.5℃ for the wild-type enzyme to Tm=65.5℃ for the mutant EGsl and 67.5℃ for the mutant EGs2. However, the two mutated enzymes had opposite approaches to produce reducing sugar from lichenin with either much higher （28%） for the former or much lower （21.6%） for the latter in comparison with their parental enzymes. The results demonstrate that directed evolution is an effective approach to improve the thermostability of a mesophilic enzyme.
基金Project supported by the National Natural Science Foundation of China （Nos. 31330055 and 31201205）, the Zhejiang Provincial Natural Science Foundation of China （No. Z3110054）, the 948 Project of Ministry of Agriculture of China （No. 2012-Z25）, and the China Agriculture Research System （No. CARS-05）
文摘13-Amylase activity （BAA） and thermostability （BAT） are important traits for malt quality. In this study, 138 Tibetan annual wild barley accessions and 20 cultivated genotypes differing in BAh, were planted and analyzed in 2009 and 2012. Significant differences were detected among genotypes in BAA and BAT. The cultivated genotypes had a mean BAA of 1137.6 U/g and a range of from 602.1 to 1407.5 U/g, while the wild accessions had a mean of 1517.9 U/g and a range of from 829.7 to 2310.0 U/g. The cultivated genotypes had a mean relative residual 13-amylase activity （RRBAA） of 61.6% and a range of from 22.2% to 82.3%, while the wild barleys had a mean of 57.8% and a range of from 21.9% to 96.1%. Moreover, there was a significant difference among genotypes in the response of RRBAA to the temperature and duration of heat treatment. The wild barleys had wider variation in BAA and BAT than cultivated genotvDes.
基金financial support from Qingyuan Huayuan Institute of Science and Technology Collaborative Innovation Co.,Ltd.,Qingyuan 511517the National Natural Science Foundation of China(No.21776051)+2 种基金the Scientific and Technological Plan of Guangdong(2019B090905007)the Guangzhou University Research Projects(YG2020017)the China Postdoctoral Science Foundation(2020M682662)。
文摘An environmentally friendly method for the synthesis of LiMnPO_(4)/C anode material for lithium-ion batteries by solvothermal method is introduced.The modification of the morphology of this precursor is altered by changing the ratio of the conditioning solvent(water-ethylene glycol solution)and the order of material addition.Ethylene glycol(EG)exerts a considerable influence on synthesizing LiMnPO_(4)/C flake-like nanocrystal,which benefits the extraction/insertion reaction of lithium ions and improves the electrochemical activity and electrochemical performance of LiMnPO_(4)/C material.When the solvent composition is H_(2)O:EG=1:3,exhibiting exceptional charge/discharge performance and rate capability,the specific discharge capacities are 155.8,153.7,148.8,141.4,129.5,and 112.6 mAh g^(−1) at the 0.1,0.2,0.5,1,2,and 5 C rates,respectively.When the charge-discharge rate returns to 0.1 C,the LiMnPO_(4)/C material shows a reversible discharge specific capacity of 153.7 mAh g^(−1).Differential scanning calorimetry(DSC)tests verify that the thermodynamic stability of the prepared LiMnPO_(4)/C(LMP)and commercial LiFePO_(4)(LFP)materials is better than that of commercial nickel-cobalt-aluminum(NCA)ternary materials.These prepared LiMnPO_(4)/C composites have high electrochemical capacity and cycle stability.
基金Supported by the National Natural Science Foundation of China(30670464,20873092,30800190)Science and Technology Project of Wuhan(200960323115)
文摘To study the thermostability of Nattokinase（subtilisin NAT,NK）,three double mutant plasmids（pET-28a-NKG61C/S98C,pET-28a-NKT22C/S87C,pET-28a-NKS24C/S87C）were constructed by site-directed mutagenesis.Target enzymes were detected using SDS-PAGE and disulfide bond formation was detected using Western blotting analysis.Thermostability was tested by rates of inactivation at certain temperature.The results showed that disulfide bond was not formed within two cysteines and the thermostability of three double mutants was not increased compared with the wild-type NK.The thermostability of NK performed in Ca2＋was stronger than in ethylenediaminetetraacetic acid（EDTA）.But when the temperature reached 62℃,the enzymes rapidly denatured and inactivated even in the presence of Ca2＋.Although the thermostability of mutants was not increased,this study shows a tendency of improving thermostability of NK in protein engineering.
基金supported by the National Natural Science Foundation of China (Nos.51390473, 51371178, 51771202)the Key Research Program of Frontier Sciences, CAS (No. QYZDY-SSWJSC027)
文摘A new phase MgYZn4 in Mg-Zn-Y alloy was studied using aberration-corrected scanning-transmission electron microscopy and first-principles calculations. Nanometer-sized MgYZn4 precipitates were formed through ordered substitutions of Y with 50% Mg atoms in MgZn2. MgYZn4 has an orthorhombic structure with a space group of Pmnn, and lattice parameters a =5.2965∧, b =9.4886∧, and c =8.5966 ∧. Importantly, both size and structure of MgYZn4 are stable at 625 K for 5 h, showing higher thermostability than MgZn2, which should be important for applications at elevated temperatures. The enhanced thermostability of MgYZn4 is attributed to the lower formation energy and bonding enhancement due to Y substitution.
基金financially supported by the Major State Basic Research Development Program of China(No.2011CBA00105)the National Natural Science Foundation of China(Nos.51002149 and 21101151)
文摘The metal-organic chemical vapor deposition （MOCVD） technique is a promising process for high-tem- perature superconductor YBa2Cu307_6（YBCO） preparation. In this technique, it is a challenge to obtain barium precursors with high volatility. In addition, the purity, evaporation characteristics, and thermostability of adopted precursors in whole process will decide the quality and reproducible results of YBCO film. In the present report, bis（2,2,6,6-tetramethyl- 3,5-heptanedionato）barium（II） （Ba（TMHD）2） was synthe- sized, and its structure was identified by PTIR, 1H NMR, 13C NMR, and ESI-MS spectroscopy. Subsequently, the thermal properties and the kinetics of decomposition were systemati- cally investigated by nonisothermal thermogravimetric anal- ysis methods. Based on the average apparent activation energy evaluated by the Ozawa, Kissinger, and Friedman methods, the volatilization process was discussed, and all results show that Ba（TMHD）2 is unstable and highly sensitive to the change of temperature during the whole evaporation process. There- fore, it is very important to choose suitable volatilization technology and conditions for avoiding Ba（TMHD）2 break- down （or thermal aging） during MOCVD process. Subse- quently, the possible conversion function is estimated through the Coats-Redfern method to characterize the evaporation patterns and follows a phase boundary reaction mechanism by the contracting surface equation with average activation energy of 118.7 kJ.mo1-1.
基金The National Natural Science Foundation of China under contract No.31401632the Program for New Century Excellent Talents in Fujian Province University,China under contract No.B15139
文摘This study aimed to improve the thermostability of arylsulfatase from Pseudoalteromonas carrageenovora. A library of P. carrageenovora arylsulfatase mutants was constructed by introducing random mutagenesis using error-prone PCR. After screening, two mutants of H260L and D84A/H260L showed enhanced thermal stability than the wild-type predecessor (WT). Site-directed mutagenesis demonstrated that only amino acid residue at Position 260 plays an important role in the thermostability of P. carrageenovora arylsulfatase. Thermal inactivation analysis showed that the half-life (t1/2) values at 55°C for H260L, H260I, H260Q, H260F and H260R were 40.6, 48.4, 30.9, 29.1 and 34.5 min, respectively, while that of WT was 9.1 min. Structure modeling demonstrated that the additional hydrogen bonds and/or optimization of surface charge-charge interactions could be responsible for the increased thermostability imparted by H260L, H260I, H260Q, H260F and H260R.
基金Supported by the National Natural Science Foundation of China (31070042,30870039,30921065)partially by Open Funding Project of the National Key Laboratory of Biochemical Engineering,China (2010KF-2)
文摘The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophilic bacterium Acidithiobacillus sp. SM-1 （SORsB）. The optimal temperatures for catalyzing sulfur oxidation were 80 ℃ （SORAT）, 85 ℃ （SORsT）, and 70 ℃ （SORsB）, respectively. The half-lives of the three SORs at their optimal catalytic conditions were 100 min （SORAT）, 58 min （SORsT）, and 37 min （SORsB）. In order to reveal the structural basis of the thermostability of these SORs, three-dimensional structural models of them were generated by homology modeling using the previously reported high-resolution X-ray structure of SORAA （from Acidianus ambivalens） as a template. The results suggest that thermostability was dependent on： （a） high number of the charged amino acid glutamic acid and the flexible amino acid proline, （b） low number of the therraolabile amino acid glutamine, （c） increased number of ion pairs, （d） decreased ratio of hydrophobie accessible solvent surface area （ASA） to charged ASA, and （e） increased volumes of the cavity. The number of cavities and the number of hydrogen bonds did not signifieantly affect the thermostability of SORs, whereas the cavity volumes increased as the thermal stability increased.
文摘The influence of thermo cycle times under variant loads and environment temperatures on the properties of Cu-16.4Zn-4Al (Re) SMA component was studied by thermostability experiments on Cu-16.4Zn-4Al SMA with the composition containing corium Re. Tangent rule was applied to determine the transformation temperature from displacement-temperature loop plot by computer in each thermal-cold cycle. The results is as follows the transformation temperature increases and shape memory property decrease with increasing load, which leads the action temperature of component to be abnormal, and the memory property decreases after overheating aging, and the memory property decreases with increasing cycle times, while the decreasing is not obvious and the recovery ratio is higher than 90% in one thousand times. It is due to the addition of corium Re which has the function of grain refinement. Therefore, it is necessary to avoid overloading and overheating in the application of such component. Thus, a kind of thermo valve that works at normal pressure and in the water as working substance was designed to replace complicate original electromechanical system.
文摘Bentonite is one of the most widespread used clays connected with various applications. In the case of foundry technology, bentonite is primarily used as a binder for mold manufacture. Thermal stability of bentonites is a natural property of clay minerals and it depends on the genesis, source and chemical composition of the clay. This property is also closely connected to bentonite structure. According to DTA analysis if only one peak of dehydroxylation is observed(about 600 oC), the cis- isomerism of bentonite is expected, while two peaks of de-hydroxylation(about 550 and 850 oC) are expected in the trans- one. In this overview, the bentonite structure, the water – bentonite interaction and the swelling behavior of bentonite in connection with the general technological properties of bentonite molding mixture are summarized. Further, various types of methods for determination of bentonite thermostability are discussed, including instrumental analytical methods as well as methods that employ evaluation of various technological properties of bentonite binders and/or bentonite molding mixtures.
文摘The solid structures and thermostabilities of Cu-Fe-O and Cu-Fe-Ce-O supported on alumina were studied by XRD, ESR, Mossbauer and TPR techniques. The studies indicate that there are Fe2CuO4, CuO and alpha-Fe2O3 phases in Cu-Fe-O with the granula of less than 13 nm. With the catalyst pretreatment temperature rising, the crystallite of Fe2CuO4 in the catalysts grows up and that of CuO disappears gradually. The presence of Ce leads to the increase of Cu2+ concentration, inhibits the crystal growth of CuO and Fe2CuO4 in the catalyst except that of Fe2O3, and eliminates the difference for reductive reaction of oxygen in Fe-O and Cu-O. At 800 degrees C, the crystal growth of Fe2O3 in Cu-Fe-Ce-O is slower than that in Cu-Fe-O, i.e., CeO2 in Cu-Fe-Ce-O inhibits the growth of Fe2O3 phase effectively, and enhances the thermostability of catalysts so as to avoid the sintering of active elements in catalysts. CeO2 promotes the reducibility of catalysts at lower temperature.
基金financially supported by the Major State Basic Research Development Program of China(973Program)(No.2011CBA00105)the National Natural Science Foundation of China(Nos.51002149and21101151)
文摘The metal-organic chemical vapor deposition (MOCVD) technique is a promising process for high-temperature superconductor YBa2Cu3O7-δ(YBCO) preparation. In this technique, it is a challenge to obtain barium precursors with high volatility. In addition, the purity, evaporation characteristics and thermostability of adopted precursors in the whole process would decide the quality and reproducible results of YBCO film. In the present report, the barium precursor containing 2,2,6,6-tetramethylheptane-3,5-dionate and tetraethylenepentamine ligands (Ba(TMHD)-tetraen) was synthesized and identified by FTIR, 1H NMR, 13C NMR and ESI-MS spectroscopy. Subsequently the thermal property and the kinetics of decomposition were systematically investigated by combining non-isothermal thermogravimetric analysis methods (TGA), Ozawa, Kissinger and Friedman methods. On the basis of the apparent activation energy of the evaporation process, the thermostability and evaporation characteristics of the precursors were discussed. All results show that Ba(TMHD)-tetraen has higher volatility than Ba(TMHD)2, but it is unstable and highly sensitive to the change of temperature during the whole evaporation process. Therefore, it is very important to choose suitable volatilization technology and conditions for avoiding Ba(TMHD)-tetraen breakdown (or thermal aging) during the MOCVD process.
文摘A nanometer porphyrin trimer was firstly synthesized with 1 ,3-dibromopropane as a bridge-linked agent and the fluorescence property and thermostability were studied. The results show that the fluorescence property and thermostability of the trimer are different from those of monoporphyrin. The effects of the molecule structure on the optical property and the thermostability were also studied in detail.
基金Project supported by Major State Basic Research Development Program of China (973 Program) (2011CBA00105)National Natural Science Foundation of China (51002149, 21101151)
文摘The metal-organic chemical vapor deposition （MOCVD） technique is a promising process for high temperature superconductor YBa2Cu3O7-δ （YBCO） preparation. In this technique, the purity, evaporation characteristics and thermostability of adopted precursors will de- cide the quality and reproducible results of YBCO film. In the present report, tris（2,2,6,6-tetramethyl-3,5-heptanedionato）yttrium（III） （Y（TMHD）3） was synthesized by the interaction of yttrium nitrate hydrate with TMHD in methanol solution, and its structure was identified by FTIR, 1H NMR, 13C NMR and EI-MS spectroscopy. Subsequently, the thermal property and the kinetics of decomposition were system- atically investigated by non-isothermal thermogravimetric analysis methods （TGA） at different heating rates in streams of N2, and the average apparent activation energy of evaporation process was evaluated by the Ozawa, Kissinger and Friedman methods. The possible conversion function was estimated through the Coats-Redfern method to characterize the evaporation patterns and followed a phase boundary reaction mechanism by the contracting area equation with average activation energy of 88.9 kJ/mol.
文摘The glass formability of NiBSimelt and the thermostability of this metallic glass formedfrom the the melt can be enhanced by eliminating the heterogeneous catalystg. The purificationwas done by cyclical superheating melt in special glasses and subsequently cyclicallysuperheating it in an electromagnetic levitation apparatus. The purified NiBSiamorphoussample sized up to 20 ~ I0 x 0.5 mm was prepared as four times the thickness of unpurifiedones.
