The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent t...The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent to acidity.In β zeolite, polymorph A is less stable than polymorph B.The chirality of β zeolite can be modified by the method of acid treatment.展开更多
[ Objective] The study aimed to discuss the suitable storage conditions of fermented Lycium barbarum wine. [ Methodl In view of the fact that volatile acid in Lycium barbarum wine is unstable during storage process, w...[ Objective] The study aimed to discuss the suitable storage conditions of fermented Lycium barbarum wine. [ Methodl In view of the fact that volatile acid in Lycium barbarum wine is unstable during storage process, we analyzed the stability changes of volatile acid in Lycium barba- rum wine with storage temperature, pH and SO2 content. [Result] When temperature was 5℃ pH was 3.7 or 3. 8, and residuary SO2 content was 60 mg/L, volatile acid in Lycium barbarum wine was relatively stable. [ Conclusion] The research could provide theoretical foundations for controlling the stability of volatile acid in Lycium barbarum wine.展开更多
To accomplish their functions, proteins have to achieve different conformations accompanied by conformational transitions. However, the relationship between the preference of amino acids and the stability of the secon...To accomplish their functions, proteins have to achieve different conformations accompanied by conformational transitions. However, the relationship between the preference of amino acids and the stability of the secondary structure is still unclear. Here we perform molecular simulations on a series of helical structures. Our data show that the dissociation energy of the helical structure is related to the preference of amino acids, and the electrostatic repulsion of the residue i and i ＋ 3/4 with the same sign of charge destabilizes the alpha helix.展开更多
Ca-Fe-Si material(CIS),a novel composite material rich in calcium,iron,manganese and silicon showed marvelous immobilization properties for heavy metal(loid)s in soils.To elucidate the acid stability of Cd fixed by CI...Ca-Fe-Si material(CIS),a novel composite material rich in calcium,iron,manganese and silicon showed marvelous immobilization properties for heavy metal(loid)s in soils.To elucidate the acid stability of Cd fixed by CIS(CIS-Cd)and the underlying immobilizationmechanisms,the acid dissolution characteristics of CIS-Cdwere investigated by using acid titration method and X-ray diffraction(XRD)technique.The results showed that CIS-Cd had distinctive acid buffering capacity in different pH ranges.Based on the titration curve between dissolution rate of CIS-Cd and pH,CIS-Cd can be divided into non acid-stable Cd(9.4%),moderately acid-stable Cd(22.5%)and acid-stable Cd(68.1%).XRD analysis of CIS-Cd at different pH intervals and the correlation curves of dissolution rates of Cd and concomitant elements indicated that non acid-stable Cdwas mainly bound by carbonate,silicate and sulfate(CdCO_(3),Cd_(2)SiO_(4) and CdSO_(4))or co-precipitated with the corresponding calcium salts.Moderately acid-stable Cd was mainly bound by magnesium-aluminum-silicon containing minerals or electrically bound bymanganese iron minerals.Acid-stable Cd remaining undissolved at pH<2.42 included CdFe_(2)O_(4) and ferromanganese minerals strongly bound Cd.It was by multilateral fixation mechanisms that Ca-Fe-Si material possessed marvelous immobilization capability for Cd and strong resilience to environmental acidification as well.The findings implicated that proper combination of calcium-iron-silicon containing minerals could develop novel promising amendments with high efficiency in heavy metal(loid)s immobilization and strong resilience to environmental change.展开更多
Bilayer-silane-coated Fe304 nanoparticles with inner layer of tetraethoxy silane （TEOS） and outer layer of vinyltriethoxysilane （VTEO） were generated to enhance their acid resistance. These nanoparticles were copo...Bilayer-silane-coated Fe304 nanoparticles with inner layer of tetraethoxy silane （TEOS） and outer layer of vinyltriethoxysilane （VTEO） were generated to enhance their acid resistance. These nanoparticles were copolymerized with vinylbenzyl chloride （VBC） using suspension polymerization, and then post-crosslinked. The resulting hypercrosslinked magnetic resin M150 presented specific bimodal property with large specific surface area of 1109 m2/g. It exhibited more excellent adsorption capacity of p- nitrophenol compared to another two magnetic adsorbents Q150 and MIEX~. Moreover, the acid stable property of the magnetite in MI50 extended its application at low pH value.展开更多
An organic ultraviolet （UV） ray absorbent, p-aminobenzoic acid （PABA） was intercalated into a Zn-Ti layered double hydroxide （LDH） precursor by an anion-exchange reaction to obtain ZnTi-PABA-LDH, a new organic-i...An organic ultraviolet （UV） ray absorbent, p-aminobenzoic acid （PABA） was intercalated into a Zn-Ti layered double hydroxide （LDH） precursor by an anion-exchange reaction to obtain ZnTi-PABA-LDH, a new organic-inorganic nanocomposite. The structure and the thermal stability of ZnTi-PABA-LDH were characterized by XRD, FT-IR and TG-DTA. The results indicate ZnTi-PABA-LDH, synthesized by this method, exhibit relatively high crystallinity, and markedly enhanced thermal stability of PABA after intercalation into ZnTi-LDH. The UV-vis-NIR spectrophotometric and ESR data show excellent UV ray resistance and greatly decreased photocatalytic activity when PABA is intercalated into the interlayers of the ZnTi-LDH. The studies suggest that ZnTi-PABA-LDH may have potential applications as safe sunscreen materials.展开更多
The purpose of this article is to propose the idea of ＂a partial stability constant＂ for the complex formation of polyamine polyacetic acids with tripositive rare earth ion. Each coordinating group has its own chara...The purpose of this article is to propose the idea of ＂a partial stability constant＂ for the complex formation of polyamine polyacetic acids with tripositive rare earth ion. Each coordinating group has its own characteristic stability constant,i.e.,＂the partial stability constant＂ and simple numerical addition can be used among the partial logarithm of the stability constant（PLSC）, for explanation of the total stability constants. The structures of the rare earth-diethylenetriamine-N,N,N＇,N＇,N＂-pentaacetic acid（DTPA）complexes in aqueous solution has been discussed from the point of PLSC.展开更多
HZSM-5, Al_2O_3, TiO_2 and SiO_2 supported CeO_2-ZrO_2-CrO_x catalysts were prepared by deposition-precipitation method and tested for deep catalytic oxidation of 1,2-dichloroethane（DCE）, as one of the common chlori...HZSM-5, Al_2O_3, TiO_2 and SiO_2 supported CeO_2-ZrO_2-CrO_x catalysts were prepared by deposition-precipitation method and tested for deep catalytic oxidation of 1,2-dichloroethane（DCE）, as one of the common chlorinated organic pollutants. All the catalysts were characterized by means of N_2 adsorption-desorption, X-ray photoelectron spectroscopy（XPS）, ammonia-temperatureprogrammed desorption（NH_3-TPD） and hydrogen temperature-programmed reduction（H2-TPR）. The characterization results revealed that there was strongly synergistic effect between the oxidizability of CZCr species and the acidity of supports, which obviously promoted the catalytic activity for DCE degradation. 20% CZCr/HZSM-5 showed the highest activity and good durability during the long-term continuous test. The catalytic activity decreased in the order： 20%CZCr/HZSM-5〉CZCr〉20%CZCr/TiO_2〉20%CZCr/Al_2O_3〉20%CZCr/SiO_2.展开更多
A series of CeO2–ZrO2–WO3（CZW）catalysts prepared by a hydrothermal synthesis method showed excellent catalytic activity for selective catalytic reduction（SCR）of NO with NH3 over a wide temperature of 150–550℃....A series of CeO2–ZrO2–WO3（CZW）catalysts prepared by a hydrothermal synthesis method showed excellent catalytic activity for selective catalytic reduction（SCR）of NO with NH3 over a wide temperature of 150–550℃.The effect of hydrothermal treatment of CZW catalysts on SCR activity was investigated in the presence of 10% H2O.The fresh catalyst showed above 90% NOx conversion at 201–459℃,which is applicable to diesel exhaust NOx purification（200–440℃）.The SCR activity results indicated that hydrothermal aging decreased the SCR activity of CZW at low temperatures（below 300℃）,while the activity was notably enhanced at high temperature（above 450℃）.The aged CZW catalyst（hydrothermal aging at 700℃ for 8 hr）showed almost 80% NOx conversion at 229–550℃,while the V2O5–WO3/TiO2 catalyst presented above 80% NOx conversion at 308–370℃.The effect of structural changes,acidity,and redox properties of CZW on the SCR activity was investigated.The results indicated that the excellent hydrothermal stability of CZW was mainly due to the CeO2–ZrO2 solid solution,amorphous WO3 phase and optimal acidity.In addition,the formation of WO3 clusters increased in size as the hydrothermal aging temperature increased,resulting in the collapse of structure,which could further affect the acidity and redox properties.展开更多
In order to develop novel LpxC inhibitors with good activities and metabolic stability, two series of compounds with hydrophilic terminus have been synthesized and their in vitro antibacterial activities against Esche...In order to develop novel LpxC inhibitors with good activities and metabolic stability, two series of compounds with hydrophilic terminus have been synthesized and their in vitro antibacterial activities against Escherichial coil and Pseudomonas aemginosa were evaluated. Especially, compounds 22b and c exhibited comparable antibacterial activities to CHIR-090 and better metabolic stability than CHIR-090 and LPC-011 in liver microsomes （rat and mouse）, which indicated the terminal methylsulfone may be a preferred structure in the design of LpxC inhibitors and worthy of further investigations.展开更多
文摘The stability of beta zeollie in acid solution and the effect of acid treatment on the polymorphs in beta zeolite were studied. This zeolite is easily dealuminated by HCI treatment but its framework highly resistent to acidity.In β zeolite, polymorph A is less stable than polymorph B.The chirality of β zeolite can be modified by the method of acid treatment.
文摘[ Objective] The study aimed to discuss the suitable storage conditions of fermented Lycium barbarum wine. [ Methodl In view of the fact that volatile acid in Lycium barbarum wine is unstable during storage process, we analyzed the stability changes of volatile acid in Lycium barba- rum wine with storage temperature, pH and SO2 content. [Result] When temperature was 5℃ pH was 3.7 or 3. 8, and residuary SO2 content was 60 mg/L, volatile acid in Lycium barbarum wine was relatively stable. [ Conclusion] The research could provide theoretical foundations for controlling the stability of volatile acid in Lycium barbarum wine.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11247010,11175055,11475053 and 11347017the Natural Science Foundation for Distinguished Young Scholars of Hebei Province under Grant No C2015202340+1 种基金the Natural Science Foundation of Hebei Province under Grant Nos C2012202079 and C201400305the Scientific Innovation Fund for Excellent Young Scientists of Hebei University of Technology under Grant No 2015010
文摘To accomplish their functions, proteins have to achieve different conformations accompanied by conformational transitions. However, the relationship between the preference of amino acids and the stability of the secondary structure is still unclear. Here we perform molecular simulations on a series of helical structures. Our data show that the dissociation energy of the helical structure is related to the preference of amino acids, and the electrostatic repulsion of the residue i and i ＋ 3/4 with the same sign of charge destabilizes the alpha helix.
基金supported by the National Natural Science Foundation of China(No.41877121)the Key-Area Research and Development Program of Guangdong Province(No.2020B0202080001)the Guangdong Laboratory for Lingnan Modern Agriculture Project(No.NT2021010).
文摘Ca-Fe-Si material(CIS),a novel composite material rich in calcium,iron,manganese and silicon showed marvelous immobilization properties for heavy metal(loid)s in soils.To elucidate the acid stability of Cd fixed by CIS(CIS-Cd)and the underlying immobilizationmechanisms,the acid dissolution characteristics of CIS-Cdwere investigated by using acid titration method and X-ray diffraction(XRD)technique.The results showed that CIS-Cd had distinctive acid buffering capacity in different pH ranges.Based on the titration curve between dissolution rate of CIS-Cd and pH,CIS-Cd can be divided into non acid-stable Cd(9.4%),moderately acid-stable Cd(22.5%)and acid-stable Cd(68.1%).XRD analysis of CIS-Cd at different pH intervals and the correlation curves of dissolution rates of Cd and concomitant elements indicated that non acid-stable Cdwas mainly bound by carbonate,silicate and sulfate(CdCO_(3),Cd_(2)SiO_(4) and CdSO_(4))or co-precipitated with the corresponding calcium salts.Moderately acid-stable Cd was mainly bound by magnesium-aluminum-silicon containing minerals or electrically bound bymanganese iron minerals.Acid-stable Cd remaining undissolved at pH<2.42 included CdFe_(2)O_(4) and ferromanganese minerals strongly bound Cd.It was by multilateral fixation mechanisms that Ca-Fe-Si material possessed marvelous immobilization capability for Cd and strong resilience to environmental acidification as well.The findings implicated that proper combination of calcium-iron-silicon containing minerals could develop novel promising amendments with high efficiency in heavy metal(loid)s immobilization and strong resilience to environmental change.
基金support provided by Program for Changjiang Scholars and Innovative Research Team in University,NSFC(Nos.50825802 and 51178215)Jiangsu Nature Science Fund(Nos. BK2010006 and BK2011032)P.R.China
文摘Bilayer-silane-coated Fe304 nanoparticles with inner layer of tetraethoxy silane （TEOS） and outer layer of vinyltriethoxysilane （VTEO） were generated to enhance their acid resistance. These nanoparticles were copolymerized with vinylbenzyl chloride （VBC） using suspension polymerization, and then post-crosslinked. The resulting hypercrosslinked magnetic resin M150 presented specific bimodal property with large specific surface area of 1109 m2/g. It exhibited more excellent adsorption capacity of p- nitrophenol compared to another two magnetic adsorbents Q150 and MIEX~. Moreover, the acid stable property of the magnetite in MI50 extended its application at low pH value.
基金supported by the National Natural Science Foundation of China (No. 21301012)
文摘An organic ultraviolet （UV） ray absorbent, p-aminobenzoic acid （PABA） was intercalated into a Zn-Ti layered double hydroxide （LDH） precursor by an anion-exchange reaction to obtain ZnTi-PABA-LDH, a new organic-inorganic nanocomposite. The structure and the thermal stability of ZnTi-PABA-LDH were characterized by XRD, FT-IR and TG-DTA. The results indicate ZnTi-PABA-LDH, synthesized by this method, exhibit relatively high crystallinity, and markedly enhanced thermal stability of PABA after intercalation into ZnTi-LDH. The UV-vis-NIR spectrophotometric and ESR data show excellent UV ray resistance and greatly decreased photocatalytic activity when PABA is intercalated into the interlayers of the ZnTi-LDH. The studies suggest that ZnTi-PABA-LDH may have potential applications as safe sunscreen materials.
文摘The purpose of this article is to propose the idea of ＂a partial stability constant＂ for the complex formation of polyamine polyacetic acids with tripositive rare earth ion. Each coordinating group has its own characteristic stability constant,i.e.,＂the partial stability constant＂ and simple numerical addition can be used among the partial logarithm of the stability constant（PLSC）, for explanation of the total stability constants. The structures of the rare earth-diethylenetriamine-N,N,N＇,N＇,N＂-pentaacetic acid（DTPA）complexes in aqueous solution has been discussed from the point of PLSC.
基金Project supports from National Nature Science Foundation of China(21177110)
文摘HZSM-5, Al_2O_3, TiO_2 and SiO_2 supported CeO_2-ZrO_2-CrO_x catalysts were prepared by deposition-precipitation method and tested for deep catalytic oxidation of 1,2-dichloroethane（DCE）, as one of the common chlorinated organic pollutants. All the catalysts were characterized by means of N_2 adsorption-desorption, X-ray photoelectron spectroscopy（XPS）, ammonia-temperatureprogrammed desorption（NH_3-TPD） and hydrogen temperature-programmed reduction（H2-TPR）. The characterization results revealed that there was strongly synergistic effect between the oxidizability of CZCr species and the acidity of supports, which obviously promoted the catalytic activity for DCE degradation. 20% CZCr/HZSM-5 showed the highest activity and good durability during the long-term continuous test. The catalytic activity decreased in the order： 20%CZCr/HZSM-5〉CZCr〉20%CZCr/TiO_2〉20%CZCr/Al_2O_3〉20%CZCr/SiO_2.
基金supported by the National Natural Science Foundation of China(Nos.U1137603,21307047)the Opening Project of Key Laboratory of Green Catalysis of Sichuan Institutes of High Education(No.LYJ1309)
文摘A series of CeO2–ZrO2–WO3（CZW）catalysts prepared by a hydrothermal synthesis method showed excellent catalytic activity for selective catalytic reduction（SCR）of NO with NH3 over a wide temperature of 150–550℃.The effect of hydrothermal treatment of CZW catalysts on SCR activity was investigated in the presence of 10% H2O.The fresh catalyst showed above 90% NOx conversion at 201–459℃,which is applicable to diesel exhaust NOx purification（200–440℃）.The SCR activity results indicated that hydrothermal aging decreased the SCR activity of CZW at low temperatures（below 300℃）,while the activity was notably enhanced at high temperature（above 450℃）.The aged CZW catalyst（hydrothermal aging at 700℃ for 8 hr）showed almost 80% NOx conversion at 229–550℃,while the V2O5–WO3/TiO2 catalyst presented above 80% NOx conversion at 308–370℃.The effect of structural changes,acidity,and redox properties of CZW on the SCR activity was investigated.The results indicated that the excellent hydrothermal stability of CZW was mainly due to the CeO2–ZrO2 solid solution,amorphous WO3 phase and optimal acidity.In addition,the formation of WO3 clusters increased in size as the hydrothermal aging temperature increased,resulting in the collapse of structure,which could further affect the acidity and redox properties.
基金National Science and Technology Major Project for the support of this researchsupported by Key New Drug Creation and Manufacturing Program,China (No.2014ZX09507009-016)
文摘In order to develop novel LpxC inhibitors with good activities and metabolic stability, two series of compounds with hydrophilic terminus have been synthesized and their in vitro antibacterial activities against Escherichial coil and Pseudomonas aemginosa were evaluated. Especially, compounds 22b and c exhibited comparable antibacterial activities to CHIR-090 and better metabolic stability than CHIR-090 and LPC-011 in liver microsomes （rat and mouse）, which indicated the terminal methylsulfone may be a preferred structure in the design of LpxC inhibitors and worthy of further investigations.
