In CZTSSe solar cells,a simple sodium-incorporation post-treatment method toward solution-processed Cu2Zn Sn S4precursor films is presented in this work.An ultrathin NaCl film is deposited on Cu2Zn Sn S4precursor film...In CZTSSe solar cells,a simple sodium-incorporation post-treatment method toward solution-processed Cu2Zn Sn S4precursor films is presented in this work.An ultrathin NaCl film is deposited on Cu2Zn Sn S4precursor films by spin-coating NaCl solution.In subsequent selenization process,the introduction of Na Cl is found to be benefacial for the formation of Cu2-xSe,which can further facilitate the element transportation,leading to dense and smooth CZTSSe films with large grains and less impurity Cu2Sn(S,Se)3phase.SIMS depth profiles confirm the gradient distribution of the sodium element in Na-doped absorbers.Photoluminescence spectra show that the introduction of appropriate sodium into the absorber can inhibit the band tail states.As high as 11.18% of power conversion efficiency(PCE)is achieved for the device treated with 5 mg mL^-1 NaCl solution,and an average efficiency of Na-doped devices is 10.71%,13%higher than that of the control groups(9.45%).Besides,the depletion width and the charge recombination lifetime can also have regular variation with sodium treatment.This work offers an easy modification method for high-quality Na-doped CZTSSe films and high-performance devices,in the meantime,it can also help to further understand the effects of sodium in CZTSSe solar cells.展开更多
AIM: To investigate the effects of selenium in rat retinal ischemia reperfusion(IR) model and compare pretreatment and post-treatment use.METHODS: Selenium pre-treatment group(n =8) was treated with intraperitoneal(i....AIM: To investigate the effects of selenium in rat retinal ischemia reperfusion(IR) model and compare pretreatment and post-treatment use.METHODS: Selenium pre-treatment group(n =8) was treated with intraperitoneal(i.p.) selenium 0.5 mg/kg for7 d and terminated 24 h after the IR injury. Selenium posttreatment group( n = 8) was treated with i. p. selenium0.5 mg/kg for 7d after the IR injury with termination at the end of the 7d period. Sham group(n =8) received i.p.saline injections identical to the selenium volume for 7d with termination 24 h after the IR injury. Control group(n =8) received no intervention. Main outcome measures were retina superoxide dismutase(SOD), glutathione(GSH),total antioxidant status(TAS), malondialdehyde(MDA),DNA fragmentation levels, and immunohistological apoptosis evaluation.RESULTS: Compared to the Sham group, selenium pre-treatment had a statistical difference in all parameters except SOD. Post-treatment selenium also resulted in statistical differences in all parameters except the MDA levels. When comparing selenium groups, the pre-treatment selenium group had a statistically higher success in reduction of markers of cell damage such as MDA and DNA fragmentation. In contrast, the post-selenium treatment group had resulted in statisticallyhigher levels of GSH. Histologically both selenium groups succeeded to limit retinal thickening and apoptosis. Pre-treatment use was statistically more successful in decreasing apoptosis in ganglion cell layer compared to post-treatment use.CONCLUSION: Selenium was successful in retinal protection in IR injuries. Pre-treatment efficacy was superior in terms of prevention of tissue damage and apoptosis.展开更多
A rural model composting toilet system still had some pathogens in the compost after months of operation and hence requires a post-treatment. The aim of the study was to sanitize compost withdrawn from the composting ...A rural model composting toilet system still had some pathogens in the compost after months of operation and hence requires a post-treatment. The aim of the study was to sanitize compost withdrawn from the composting toilet by setting post-treatment conditions. The kinetics inactivation of MS2 bacteriophage, selected as indicator for pathogenic viruses were determined during post-treatment at different temperatures (30°C, 40°C and 50°C) with varying moisture contents (50%, 60% and 70%). As a result, the inactivation rates during the post-treatment were 0.093 - 0.020 h-1, 0.025 - 0.088 h1, 0.447 - 0.100 h-1 at 30°C, 40°C and 50°C respectively. The inactivation rate coefficient (k) values of MS2 bacteriophage depended on higher temperature but not on moisture content.展开更多
According to the high thickness swelling and low dimensional stability of Poplars particleboard, this paper studied the effect of heat post-treatment on the board properties. The results indicated that the post-treatm...According to the high thickness swelling and low dimensional stability of Poplars particleboard, this paper studied the effect of heat post-treatment on the board properties. The results indicated that the post-treatment could be a very effective way to produce dimensinaly stable fast-growing poplars particleboard. The thickness swelling of the board decreased with increasing the time and temperatures of post-heat treatment. So under190℃, being treated for 15 min., the total thickness swelling (TS1) of the board was 8.96%, reduced by 22.88%. The irreversible thickness swelling (TS2) was also reduced with the post-treatment of 190 ℃ or 220℃; The reversible thickness swelling (TS3) was not signifcantly changed when the time of treatment increased up to 25 min. under 190℃.展开更多
TS-1/SiO_2 extrudate was post-treated with mixed solution of tetrapropyl ammonium hydroxide(TPAOH)and various ammonium salts solution(NH_4F,(NH_4)_3PO_4,(NH_4)_2CO_3,(NH_4)_2SO_4,NH_4CH_3CO_2,NH_4NO_3,NH_4Cl and(NH_4)...TS-1/SiO_2 extrudate was post-treated with mixed solution of tetrapropyl ammonium hydroxide(TPAOH)and various ammonium salts solution(NH_4F,(NH_4)_3PO_4,(NH_4)_2CO_3,(NH_4)_2SO_4,NH_4CH_3CO_2,NH_4NO_3,NH_4Cl and(NH_4)_2TiF_6).The obtained hierarchical TS-1 catalysts were characterized by many techniques and tested for propylene epoxidation using hydrogen peroxide as an oxidant in a fixed-bed reactor.It was shown that the physicochemical and catalytic properties of the treated TS-1/SiO_2 extrudate depended on the types of ammonium salts added.Compared to the treatment with TPAOH alone,the treatment with a mixed solution of TPAOH and some ammonium salts can greatly improve the catalytic properties of the treated TS-1/SiO_2 extrudate.Some of these ammonium salts were favorable for the incorporation of titanium in the framework,and the beneficial effect depended on the types of ammonium salt.TS-1/SiO_2 extrudate treated with a mixed solution of TPAOH and(NH_4)_3PO_4 exhibited the highest catalyst stability in propylene epoxidation.Such catalytic property can be correlated to high crystallinity,more framework titanium,large specific surface area and large external surface area.展开更多
Properties of high absorbency and modulus (gel strength) were both needed in applications of superabsorbent polymer (SAP). Generally, the absorption characteristic and gel strength reach a crossover point for a given ...Properties of high absorbency and modulus (gel strength) were both needed in applications of superabsorbent polymer (SAP). Generally, the absorption characteristic and gel strength reach a crossover point for a given system. Beyond this point, a given property will show improvement at the expense of another property. To synthesize SAP with properties superior to this optimum value, further modification in the process becomes essential. In our post-treatment modification of superabsorbent polymer, neither the variety of the crosslinkers, nor their amount was found the effective factors to the polymer performance, but the liquor ratio of the treating liquid to polymer. The combination of the chemical treating and heat-treating method was also explored. But this didn’t put any positive effect on SAP’s properties.展开更多
With reference to the testing standard ASTM D1894,the sliding-friction coefficient of the aluminumzinc-plated post-treatment plate was measured.To reduce the detection error in practical applications,a correction fact...With reference to the testing standard ASTM D1894,the sliding-friction coefficient of the aluminumzinc-plated post-treatment plate was measured.To reduce the detection error in practical applications,a correction factor is proposed.Although the test results showed that the relative standard deviation of the friction coefficient of the aluminum-zinc-plated post-treatment plate was 12.1%indicating that the test results experienced a certain fluctuation,it can nevertheless be used as an internal factory-controlled test method.At the same time,problems were encountered with respect to sample contact,sample edge burr,and sample surface contamination.However,measures can be taken to reduce the impact of these factors.展开更多
The porous material HZSM-5 zeolite with micro-mesopore hierarchical porosity was prepared by post-treatment(combined alkali treatment and acid leaching) of parent zeolite and its catalytic performance for benzene alky...The porous material HZSM-5 zeolite with micro-mesopore hierarchical porosity was prepared by post-treatment(combined alkali treatment and acid leaching) of parent zeolite and its catalytic performance for benzene alkylation with methanol was investigated. The effect of post-treatment on the textural properties was characterized by various techniques(including ICP-AES, XRD, nitrogen sorption isotherms, SEM, NH3-TPD, Py-IR and TG). The results indicated that the post-treatment could modify the structural and acidic properties of HZSM-5 zeolite. In this procedure, not only additional mesopores were created by selective extraction of silicon but also the acidity was tuned. Consequently, the modified HZSM-5 zeolite showed larger external surface area with less acid sites as compared to the parent zeolite. It was found out that the modified zeolite exhibited a higher benzene conversion and xylene selectivity for alkylation of benzene with methanol as well as excellent life span of the catalyst than conventional ones. This can be explained by the facts that the presence of additional mesopores improved the diffusion property in the reactions. Furthermore, the modified zeolite showed an appropriate Br?nsted acidity for effective suppression of the side reaction of methanol to olefins, thus reduced the accumulation of coke on the HZSM-5 zeolite, which was favorable for the catalyst stability. In comparison with the parent HZSM-5 zeolite,the modified zeolite by alkali treatment and acid leaching showed better performance for the benzene alkylation with methanol.展开更多
Recent studies have shown that induced expression of endogenous antioxidative enzymes through activation of the antioxidant response element/nuclear factor erythroid 2-related factor 2(Nrf2) pathway may be a neuroprot...Recent studies have shown that induced expression of endogenous antioxidative enzymes through activation of the antioxidant response element/nuclear factor erythroid 2-related factor 2(Nrf2) pathway may be a neuroprotective strategy. In this study, rat cerebral cortical neurons cultured in vitro were pretreated with 10 μM curcumin or post-treated with 5 μM curcumin, respectively before or after being subjected to oxygen-glucose deprivation and reoxygenation for 24 hours. Both pretreatment and post-treatment resulted in a significant decrease of cell injury as indicated by propidium iodide/Hoechst 33258 staining, a prominent increase of Nrf2 protein expression as indicated by western blot analysis, and a remarkable increase of protein expression and enzyme activity in whole cell lysates of thioredoxin before ischemia, after ischemia, and after reoxygenation. In addition, post-treatment with curcumin inhibited early DNA/RNA oxidation as indicated by immunocytochemistry and increased nuclear Nrf2 protein by inducing nuclear accumulation of Nrf2. These findings suggest that curcumin activates the expression of thioredoxin, an antioxidant protein in the Nrf2 pathway, and protects neurons from death caused by oxygen-glucose deprivation in an in vitro model of ischemia/reperfusion. We speculate that pharmacologic stimulation of antioxidant gene expression may be a promising approach to neuroprotection after cerebral ischemia.展开更多
In order to improve the leaching resistance of active ingredient-copper in ammoniacal copper quat-type D (ACQ-D) treated Chinese fir (Cunninghamia lanceolata Hook.),microwave post-treatments were carried out.The perce...In order to improve the leaching resistance of active ingredient-copper in ammoniacal copper quat-type D (ACQ-D) treated Chinese fir (Cunninghamia lanceolata Hook.),microwave post-treatments were carried out.The percentages of leached copper from ACQ-D treated Chinese fir with different microwave post-treatments were obtained after leaching tests by analyzing the copper retention in treated wood.The fixation mechanism of copper in the treated wood was determined with the help of SEM and FTIR spectra,while the valence conversion of copper after microwave post-treatments was studied by UV spectroscopy.Our experimental results show that the percentage of leached copper was reduced significantly after microwave post-treatment over time.This development was reinforced by allowing even more time for the treatment as well as with an increase in the power of microwave post-treatment.The leaching resistance of copper in wrapped samples was better than that in unwrapped samples,which is attributed to the combined effects of temperature and moisture content.Compared with air-dried samples,the valence conversion in the samples with microwave post-treatments changed slightly,which demonstrates that microwave post-treatments cannot impair the natural decay resistance of ACQ-D treated wood.SEM and FTIR spectra showed the presence of crystal particles formed by chemical reactions between copper and wood ingredients in wood cell walls and wood pits.Only a small amount of copper reacted with cellulose,while lignin and hemicellulose were the major bonding sites for copper in wood.Given the experimental results of mechanical properties,microwave post-treatments had a slight effect on the compression strength parallel to the grain and on the crystallinity of ACQ-D treated Chinese fir.展开更多
Developing high-performance poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)sig-nificantly widens the practical applications of flexible organic thermoelectric devices,while the water-based co-solve...Developing high-performance poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)sig-nificantly widens the practical applications of flexible organic thermoelectric devices,while the water-based co-solvent dopants and/or post-treatments are still rarely studied so far.Here,we develop a one-step post-treatment to improve the power factor of PEDOT:PSS films by using a water-based solution,which is composed of co-solvent(polar solvent dimethylacetamide(DMAC)and deionized water)and organic reducing agent L-ascorbic acid(LAA).The 80 vol.%DMAC solution significantly boosts the room-temperature electrical conductivity of the films from 5 to 964 S cm^(−1),while the Seebeck coefficient can be further enhanced from 18.7 to 25μV K−1 by treating with 0.5 mol L−1 LAA,contributing to a sig-nificantly improved power factor of 55.3μW m^(−1)K^(−2).The boosted electrical conductivity is ascribed to the separated PEDOT and PSS phases triggered by the high dielectric constant and polarity of DMAC;while the improved Seebeck coefficient is attributed to the reduced oxidation degree of PEDOT from the reducing agent LAA,both confirmed by the comprehensive structural and morphological characteri-zations.Furthermore,a maximum power factor of 64.4μW m^(−1)K^(−2)can be achieved at 360 K and the observed temperature-dependent electrical transport behavior can be well explained by the Mott variable range hopping model.Besides,a flexible thermoelectric device,assembled by the as-fabricated PEDOT:PSS films,exhibits a maximum output power of∼23 nW at a temperature difference of 25 K,indicating the potential for applying to low-grade wearable electronics.展开更多
Parallel fibrous scaffolds play a critical role in controlling the morphology of cells to be more natural and biologically inspired.Among popular tissue engineering materials,poly(2-hydroxyethyl methacrylate)(pHEMA)ha...Parallel fibrous scaffolds play a critical role in controlling the morphology of cells to be more natural and biologically inspired.Among popular tissue engineering materials,poly(2-hydroxyethyl methacrylate)(pHEMA)has been widely investigated in conventional forms due to its biocompatibility,low toxicity,and hydrophilicity.However,the swelling of pHEMA in water remains a major concern.To address this issue,randomly oriented and aligned as-spun pHEMA nanofibrous scaffolds were first fabricated at speeds of 300 and 2000 rpm in this study,which were then post-treated using either a thermal or a freeze-drying method.In cell assays,human dermal fibroblasts(HDFs)adhered to the freeze-drying treated substrates at a significantly faster rate,whereas they had a higher cell growth rate on thermally-treated substrates.Results indicated that the structural properties of pHEMA nanofibrous scaffolds and subsequent cellular behaviors were largely dependent on post-treatment methods.Moreover,this study suggests that aligned pHEMA nanofibrous substrates tended to induce regular fibroblast orientation and unidirectionally oriented actin cytoskeletons over random pHEMA nanofibrous substrates.Such information has predictive power and provides insights into promising post-treatment methods for improving the properties of aligned pHEMA scaffolds for numerous tissue engineering applications.展开更多
The exploration of high-efficient catalysts based on hierarchical Ti-containing zeolites with optimized active titanium species distribution is of great value in enhancing the epoxidation of bulky olefins. Herein, hie...The exploration of high-efficient catalysts based on hierarchical Ti-containing zeolites with optimized active titanium species distribution is of great value in enhancing the epoxidation of bulky olefins. Herein, hierarchical TS-1(MFI) zeolite with an extra-large external surface area(210 m2/g) and highly active octahedral- coordinated Ti species was prepared via organic base-assisted sequential post-treatment. Such a catalyst afforded a high turnover number value(TON, 114) in 1-octene epoxidation reaction, which was over twice than that(53) of the untreated conventional microporous TS-1 parent. According to the detailed characterization results, we revealed the hierarchical porosity construction effect of tetrapropylamonium hydroxide(TPAOH) treatment(first step) and the octahedral-coordinated Ti species fabrication effect of ethylamine(EA) treatment(second step) under hydrothermal condition. Such a facile post-treatment strategy reported in this work may provide guidance for the rational synthesis of TS-1 zeolite with enhanced catalytic activity.展开更多
In this study,Alloy 718 specimens were fabricated via selective laser melting(SLM),and the effects of different post-treatments on microstructures and mechanical properties of the alloy were systematically studied.The...In this study,Alloy 718 specimens were fabricated via selective laser melting(SLM),and the effects of different post-treatments on microstructures and mechanical properties of the alloy were systematically studied.The post-treatment techniques investigated were solid solution+dual aging(SA) and hot isostatic pressing+solid solution+dual aging treatment(HIP+SA).The results indicate that the specimens treated using SA have a columnar crystal structure similar to the as-built sample,the microstructure is partially recrystallized,and the grain size increases slightly.Meanwhile,the grain morphology is dominated by equiaxed crystals in samples treated using HIP+SA,and the microstructure is completely recrystallized,with distinct grain coarsening and a large number of twins formed.Specimens treated using SA and HIP+SA show high tensile strength and yield strength and excellent elongation at room temperature,which can be primarily attributed to the strengthening of the γ’ and γ "precipitated phases.The number of γ" precipitated phases are reduced due to the consumption of Nb to form a large amounts of δ phase and(Ti,Nb)C carbides,resulting in the strength of HIP+SA specimens being lower than that of SA specimens.展开更多
In this study, ultraviolet(UV) and vacuum ultraviolet(VUV) photolysis were investigated for the pre-treatment and post-treatment of coking wastewater. First, 6-fold diluted raw coking wastewater was irradiated by UV a...In this study, ultraviolet(UV) and vacuum ultraviolet(VUV) photolysis were investigated for the pre-treatment and post-treatment of coking wastewater. First, 6-fold diluted raw coking wastewater was irradiated by UV and VUV. It was found that 15.9%–35.4% total organic carbon(TOC) was removed after 24 hr irradiation. The irradiated effluent could be degraded by the acclimated activated sludge. Even though the VUV photolysis removed more chemical oxygen demand(COD) than UV, the UV-irradiated effluent demonstrated better biodegradability. After 4 hr UV irradiation, the biological oxygen demand BOD5/COD ratio of irradiated coking wastewater increased from 0.163 to 0.224, and its toxicity decreased to the greatest extent. Second, the biologically treated coking wastewater was irradiated by UV and VUV. Both of them were able to remove 37%–47% TOC within 8 hr irradiation.Compared to UV, VUV photolysis could significantly improve the transparency of the bio-treated effluent. VUV also reduced 7% more ammonia nitrogen(NH+4–N), 17%more nitrite nitrogen(NO-2–N), and 18% more total nitrogen(TN) than UV, producing 35%less nitrite nitrogen(NO-3–N) as a result. In conclusion, UV irradiation was better in improving the biodegradability of coking wastewater, while VUV was more effective at photolyzing the residual organic compounds and inorganic N-species in the bio-treated effluent.展开更多
Semi-solid powder rolling is a strip manufacturing process, which combines powder rolling with semi-solid rolling in one step to prepare high-performance metallic strips. A total of 7050 aluminum alloy strips were pre...Semi-solid powder rolling is a strip manufacturing process, which combines powder rolling with semi-solid rolling in one step to prepare high-performance metallic strips. A total of 7050 aluminum alloy strips were prepared by semi-solid powder rolling and then used to study the post-treatment process and evaluate qualities of post-treated strips.Three post-treatment processes involving sintering, pre-sintering—cold deformation—sintering, and hot rolling were used to process the semi-solid powder rolled strips. The results show that both swelling of pores and densification occur during solid-state sintering while microhardness increases. The decrease in density is due to that the swelling of pores has a larger effect on the density change than that of densification. The relative density reaches 92.6% with the maximum microhardness of 300 HV after ‘‘pre-sintering—cold deformation—sintering'' process. High microhardness is due to the ultrafine secondary particles uniformly distributed within the grains. The microhardness and relative density of a hot rolled strip are 176 HV and 99%, respectively, and the secondary particles disappear. Occurrence of recrystallization in these three post-treatment processes makes the grains finer.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51421002, 51627803, 91733301, 51761145042, 21501183, 51402348, 53872321, and 11874402)the Knowledge Innovation Program and the Strategic Priority Research Program (Grant XDB 12010400) of the Chinese Academy of Sciences
文摘In CZTSSe solar cells,a simple sodium-incorporation post-treatment method toward solution-processed Cu2Zn Sn S4precursor films is presented in this work.An ultrathin NaCl film is deposited on Cu2Zn Sn S4precursor films by spin-coating NaCl solution.In subsequent selenization process,the introduction of Na Cl is found to be benefacial for the formation of Cu2-xSe,which can further facilitate the element transportation,leading to dense and smooth CZTSSe films with large grains and less impurity Cu2Sn(S,Se)3phase.SIMS depth profiles confirm the gradient distribution of the sodium element in Na-doped absorbers.Photoluminescence spectra show that the introduction of appropriate sodium into the absorber can inhibit the band tail states.As high as 11.18% of power conversion efficiency(PCE)is achieved for the device treated with 5 mg mL^-1 NaCl solution,and an average efficiency of Na-doped devices is 10.71%,13%higher than that of the control groups(9.45%).Besides,the depletion width and the charge recombination lifetime can also have regular variation with sodium treatment.This work offers an easy modification method for high-quality Na-doped CZTSSe films and high-performance devices,in the meantime,it can also help to further understand the effects of sodium in CZTSSe solar cells.
文摘AIM: To investigate the effects of selenium in rat retinal ischemia reperfusion(IR) model and compare pretreatment and post-treatment use.METHODS: Selenium pre-treatment group(n =8) was treated with intraperitoneal(i.p.) selenium 0.5 mg/kg for7 d and terminated 24 h after the IR injury. Selenium posttreatment group( n = 8) was treated with i. p. selenium0.5 mg/kg for 7d after the IR injury with termination at the end of the 7d period. Sham group(n =8) received i.p.saline injections identical to the selenium volume for 7d with termination 24 h after the IR injury. Control group(n =8) received no intervention. Main outcome measures were retina superoxide dismutase(SOD), glutathione(GSH),total antioxidant status(TAS), malondialdehyde(MDA),DNA fragmentation levels, and immunohistological apoptosis evaluation.RESULTS: Compared to the Sham group, selenium pre-treatment had a statistical difference in all parameters except SOD. Post-treatment selenium also resulted in statistical differences in all parameters except the MDA levels. When comparing selenium groups, the pre-treatment selenium group had a statistically higher success in reduction of markers of cell damage such as MDA and DNA fragmentation. In contrast, the post-selenium treatment group had resulted in statisticallyhigher levels of GSH. Histologically both selenium groups succeeded to limit retinal thickening and apoptosis. Pre-treatment use was statistically more successful in decreasing apoptosis in ganglion cell layer compared to post-treatment use.CONCLUSION: Selenium was successful in retinal protection in IR injuries. Pre-treatment efficacy was superior in terms of prevention of tissue damage and apoptosis.
文摘A rural model composting toilet system still had some pathogens in the compost after months of operation and hence requires a post-treatment. The aim of the study was to sanitize compost withdrawn from the composting toilet by setting post-treatment conditions. The kinetics inactivation of MS2 bacteriophage, selected as indicator for pathogenic viruses were determined during post-treatment at different temperatures (30°C, 40°C and 50°C) with varying moisture contents (50%, 60% and 70%). As a result, the inactivation rates during the post-treatment were 0.093 - 0.020 h-1, 0.025 - 0.088 h1, 0.447 - 0.100 h-1 at 30°C, 40°C and 50°C respectively. The inactivation rate coefficient (k) values of MS2 bacteriophage depended on higher temperature but not on moisture content.
文摘According to the high thickness swelling and low dimensional stability of Poplars particleboard, this paper studied the effect of heat post-treatment on the board properties. The results indicated that the post-treatment could be a very effective way to produce dimensinaly stable fast-growing poplars particleboard. The thickness swelling of the board decreased with increasing the time and temperatures of post-heat treatment. So under190℃, being treated for 15 min., the total thickness swelling (TS1) of the board was 8.96%, reduced by 22.88%. The irreversible thickness swelling (TS2) was also reduced with the post-treatment of 190 ℃ or 220℃; The reversible thickness swelling (TS3) was not signifcantly changed when the time of treatment increased up to 25 min. under 190℃.
基金supported by National Natural Science Foundation of China (No. 21276183)
文摘TS-1/SiO_2 extrudate was post-treated with mixed solution of tetrapropyl ammonium hydroxide(TPAOH)and various ammonium salts solution(NH_4F,(NH_4)_3PO_4,(NH_4)_2CO_3,(NH_4)_2SO_4,NH_4CH_3CO_2,NH_4NO_3,NH_4Cl and(NH_4)_2TiF_6).The obtained hierarchical TS-1 catalysts were characterized by many techniques and tested for propylene epoxidation using hydrogen peroxide as an oxidant in a fixed-bed reactor.It was shown that the physicochemical and catalytic properties of the treated TS-1/SiO_2 extrudate depended on the types of ammonium salts added.Compared to the treatment with TPAOH alone,the treatment with a mixed solution of TPAOH and some ammonium salts can greatly improve the catalytic properties of the treated TS-1/SiO_2 extrudate.Some of these ammonium salts were favorable for the incorporation of titanium in the framework,and the beneficial effect depended on the types of ammonium salt.TS-1/SiO_2 extrudate treated with a mixed solution of TPAOH and(NH_4)_3PO_4 exhibited the highest catalyst stability in propylene epoxidation.Such catalytic property can be correlated to high crystallinity,more framework titanium,large specific surface area and large external surface area.
文摘Properties of high absorbency and modulus (gel strength) were both needed in applications of superabsorbent polymer (SAP). Generally, the absorption characteristic and gel strength reach a crossover point for a given system. Beyond this point, a given property will show improvement at the expense of another property. To synthesize SAP with properties superior to this optimum value, further modification in the process becomes essential. In our post-treatment modification of superabsorbent polymer, neither the variety of the crosslinkers, nor their amount was found the effective factors to the polymer performance, but the liquor ratio of the treating liquid to polymer. The combination of the chemical treating and heat-treating method was also explored. But this didn’t put any positive effect on SAP’s properties.
文摘With reference to the testing standard ASTM D1894,the sliding-friction coefficient of the aluminumzinc-plated post-treatment plate was measured.To reduce the detection error in practical applications,a correction factor is proposed.Although the test results showed that the relative standard deviation of the friction coefficient of the aluminum-zinc-plated post-treatment plate was 12.1%indicating that the test results experienced a certain fluctuation,it can nevertheless be used as an internal factory-controlled test method.At the same time,problems were encountered with respect to sample contact,sample edge burr,and sample surface contamination.However,measures can be taken to reduce the impact of these factors.
基金Supported by the National Natural Science Foundation of China(NSFC-21476207 and NSFC-21506189)the National Basic Research Program of China(973 Program)(2011CB710800)
文摘The porous material HZSM-5 zeolite with micro-mesopore hierarchical porosity was prepared by post-treatment(combined alkali treatment and acid leaching) of parent zeolite and its catalytic performance for benzene alkylation with methanol was investigated. The effect of post-treatment on the textural properties was characterized by various techniques(including ICP-AES, XRD, nitrogen sorption isotherms, SEM, NH3-TPD, Py-IR and TG). The results indicated that the post-treatment could modify the structural and acidic properties of HZSM-5 zeolite. In this procedure, not only additional mesopores were created by selective extraction of silicon but also the acidity was tuned. Consequently, the modified HZSM-5 zeolite showed larger external surface area with less acid sites as compared to the parent zeolite. It was found out that the modified zeolite exhibited a higher benzene conversion and xylene selectivity for alkylation of benzene with methanol as well as excellent life span of the catalyst than conventional ones. This can be explained by the facts that the presence of additional mesopores improved the diffusion property in the reactions. Furthermore, the modified zeolite showed an appropriate Br?nsted acidity for effective suppression of the side reaction of methanol to olefins, thus reduced the accumulation of coke on the HZSM-5 zeolite, which was favorable for the catalyst stability. In comparison with the parent HZSM-5 zeolite,the modified zeolite by alkali treatment and acid leaching showed better performance for the benzene alkylation with methanol.
基金supported by grants from the National Natural Science Foundation of China,No.81171090Natural Science Foundation of Chongqing Education Committee of China,No.KJ110313+1 种基金Foundation of Key State Laboratory of Neurobiology of Fudan University in China,No.10-08Foundation of Key Laboratory of Ministry of Education of the Third Medical Military University in China
文摘Recent studies have shown that induced expression of endogenous antioxidative enzymes through activation of the antioxidant response element/nuclear factor erythroid 2-related factor 2(Nrf2) pathway may be a neuroprotective strategy. In this study, rat cerebral cortical neurons cultured in vitro were pretreated with 10 μM curcumin or post-treated with 5 μM curcumin, respectively before or after being subjected to oxygen-glucose deprivation and reoxygenation for 24 hours. Both pretreatment and post-treatment resulted in a significant decrease of cell injury as indicated by propidium iodide/Hoechst 33258 staining, a prominent increase of Nrf2 protein expression as indicated by western blot analysis, and a remarkable increase of protein expression and enzyme activity in whole cell lysates of thioredoxin before ischemia, after ischemia, and after reoxygenation. In addition, post-treatment with curcumin inhibited early DNA/RNA oxidation as indicated by immunocytochemistry and increased nuclear Nrf2 protein by inducing nuclear accumulation of Nrf2. These findings suggest that curcumin activates the expression of thioredoxin, an antioxidant protein in the Nrf2 pathway, and protects neurons from death caused by oxygen-glucose deprivation in an in vitro model of ischemia/reperfusion. We speculate that pharmacologic stimulation of antioxidant gene expression may be a promising approach to neuroprotection after cerebral ischemia.
基金the FANEDD of China (No. 200352)the Fok Ying Tong Education Foundation (No. 101028) for financial support
文摘In order to improve the leaching resistance of active ingredient-copper in ammoniacal copper quat-type D (ACQ-D) treated Chinese fir (Cunninghamia lanceolata Hook.),microwave post-treatments were carried out.The percentages of leached copper from ACQ-D treated Chinese fir with different microwave post-treatments were obtained after leaching tests by analyzing the copper retention in treated wood.The fixation mechanism of copper in the treated wood was determined with the help of SEM and FTIR spectra,while the valence conversion of copper after microwave post-treatments was studied by UV spectroscopy.Our experimental results show that the percentage of leached copper was reduced significantly after microwave post-treatment over time.This development was reinforced by allowing even more time for the treatment as well as with an increase in the power of microwave post-treatment.The leaching resistance of copper in wrapped samples was better than that in unwrapped samples,which is attributed to the combined effects of temperature and moisture content.Compared with air-dried samples,the valence conversion in the samples with microwave post-treatments changed slightly,which demonstrates that microwave post-treatments cannot impair the natural decay resistance of ACQ-D treated wood.SEM and FTIR spectra showed the presence of crystal particles formed by chemical reactions between copper and wood ingredients in wood cell walls and wood pits.Only a small amount of copper reacted with cellulose,while lignin and hemicellulose were the major bonding sites for copper in wood.Given the experimental results of mechanical properties,microwave post-treatments had a slight effect on the compression strength parallel to the grain and on the crystallinity of ACQ-D treated Chinese fir.
基金supported by the National Natural Science Foundation of China(Grant No.51802181)Natural Science Basic Research Program of Shaanxi(Grant No.2022JZ-31)+3 种基金Young Talent fund of University Association for Science and Technology in Shaanxi,China(Grant No.20210411)China Postdoctoral Sci-ence Foundation(Grant No.2021M692621)the Foundation of Shaanxi University of Science&Technology(Grant No.2017GBJ-03)ZGC thanks the financial support from the Australian Research Council,QUT capacity building professor program,and HBIS-UQ In-novation center for Sustainable Steel(ICSS)project.
文摘Developing high-performance poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate)(PEDOT:PSS)sig-nificantly widens the practical applications of flexible organic thermoelectric devices,while the water-based co-solvent dopants and/or post-treatments are still rarely studied so far.Here,we develop a one-step post-treatment to improve the power factor of PEDOT:PSS films by using a water-based solution,which is composed of co-solvent(polar solvent dimethylacetamide(DMAC)and deionized water)and organic reducing agent L-ascorbic acid(LAA).The 80 vol.%DMAC solution significantly boosts the room-temperature electrical conductivity of the films from 5 to 964 S cm^(−1),while the Seebeck coefficient can be further enhanced from 18.7 to 25μV K−1 by treating with 0.5 mol L−1 LAA,contributing to a sig-nificantly improved power factor of 55.3μW m^(−1)K^(−2).The boosted electrical conductivity is ascribed to the separated PEDOT and PSS phases triggered by the high dielectric constant and polarity of DMAC;while the improved Seebeck coefficient is attributed to the reduced oxidation degree of PEDOT from the reducing agent LAA,both confirmed by the comprehensive structural and morphological characteri-zations.Furthermore,a maximum power factor of 64.4μW m^(−1)K^(−2)can be achieved at 360 K and the observed temperature-dependent electrical transport behavior can be well explained by the Mott variable range hopping model.Besides,a flexible thermoelectric device,assembled by the as-fabricated PEDOT:PSS films,exhibits a maximum output power of∼23 nW at a temperature difference of 25 K,indicating the potential for applying to low-grade wearable electronics.
基金supported by Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),National Natural Science Foundation of China(Grant no.11372205 and 31900964)Program of Zhejiang Sci-Tech University(Grant no.11110231281803)+1 种基金Scientific Research Foundation of Zhejiang Sci-Tech University(Grant no.11112932618215)the Fundamental Research Funds of Zhejiang Sci-Tech University(Grant no.2020Q002).
文摘Parallel fibrous scaffolds play a critical role in controlling the morphology of cells to be more natural and biologically inspired.Among popular tissue engineering materials,poly(2-hydroxyethyl methacrylate)(pHEMA)has been widely investigated in conventional forms due to its biocompatibility,low toxicity,and hydrophilicity.However,the swelling of pHEMA in water remains a major concern.To address this issue,randomly oriented and aligned as-spun pHEMA nanofibrous scaffolds were first fabricated at speeds of 300 and 2000 rpm in this study,which were then post-treated using either a thermal or a freeze-drying method.In cell assays,human dermal fibroblasts(HDFs)adhered to the freeze-drying treated substrates at a significantly faster rate,whereas they had a higher cell growth rate on thermally-treated substrates.Results indicated that the structural properties of pHEMA nanofibrous scaffolds and subsequent cellular behaviors were largely dependent on post-treatment methods.Moreover,this study suggests that aligned pHEMA nanofibrous substrates tended to induce regular fibroblast orientation and unidirectionally oriented actin cytoskeletons over random pHEMA nanofibrous substrates.Such information has predictive power and provides insights into promising post-treatment methods for improving the properties of aligned pHEMA scaffolds for numerous tissue engineering applications.
基金This work was supported by the National Natural Science Foundation of China (Nos.21835002,21621001,22001090)the "111" Project of China(No.B17020)the China Postdoctoral Science Foundation(No.2021T140259).
文摘The exploration of high-efficient catalysts based on hierarchical Ti-containing zeolites with optimized active titanium species distribution is of great value in enhancing the epoxidation of bulky olefins. Herein, hierarchical TS-1(MFI) zeolite with an extra-large external surface area(210 m2/g) and highly active octahedral- coordinated Ti species was prepared via organic base-assisted sequential post-treatment. Such a catalyst afforded a high turnover number value(TON, 114) in 1-octene epoxidation reaction, which was over twice than that(53) of the untreated conventional microporous TS-1 parent. According to the detailed characterization results, we revealed the hierarchical porosity construction effect of tetrapropylamonium hydroxide(TPAOH) treatment(first step) and the octahedral-coordinated Ti species fabrication effect of ethylamine(EA) treatment(second step) under hydrothermal condition. Such a facile post-treatment strategy reported in this work may provide guidance for the rational synthesis of TS-1 zeolite with enhanced catalytic activity.
基金financially supported by the Key-Area Research and Development Program of Guangdong Province (No.2018B090905001)Guangdong Science and Technology Project (No.2018B090905002)+1 种基金Guangzhou Science and Technology Project (No.201807010075)Dongguan Introduction Plan of Research Team (No.201536000200027)。
文摘In this study,Alloy 718 specimens were fabricated via selective laser melting(SLM),and the effects of different post-treatments on microstructures and mechanical properties of the alloy were systematically studied.The post-treatment techniques investigated were solid solution+dual aging(SA) and hot isostatic pressing+solid solution+dual aging treatment(HIP+SA).The results indicate that the specimens treated using SA have a columnar crystal structure similar to the as-built sample,the microstructure is partially recrystallized,and the grain size increases slightly.Meanwhile,the grain morphology is dominated by equiaxed crystals in samples treated using HIP+SA,and the microstructure is completely recrystallized,with distinct grain coarsening and a large number of twins formed.Specimens treated using SA and HIP+SA show high tensile strength and yield strength and excellent elongation at room temperature,which can be primarily attributed to the strengthening of the γ’ and γ "precipitated phases.The number of γ" precipitated phases are reduced due to the consumption of Nb to form a large amounts of δ phase and(Ti,Nb)C carbides,resulting in the strength of HIP+SA specimens being lower than that of SA specimens.
基金accomplished under an "863" Exploration Project granted by the Chinese Ministry of Science and Technology (No. 2009AA06Z309)
文摘In this study, ultraviolet(UV) and vacuum ultraviolet(VUV) photolysis were investigated for the pre-treatment and post-treatment of coking wastewater. First, 6-fold diluted raw coking wastewater was irradiated by UV and VUV. It was found that 15.9%–35.4% total organic carbon(TOC) was removed after 24 hr irradiation. The irradiated effluent could be degraded by the acclimated activated sludge. Even though the VUV photolysis removed more chemical oxygen demand(COD) than UV, the UV-irradiated effluent demonstrated better biodegradability. After 4 hr UV irradiation, the biological oxygen demand BOD5/COD ratio of irradiated coking wastewater increased from 0.163 to 0.224, and its toxicity decreased to the greatest extent. Second, the biologically treated coking wastewater was irradiated by UV and VUV. Both of them were able to remove 37%–47% TOC within 8 hr irradiation.Compared to UV, VUV photolysis could significantly improve the transparency of the bio-treated effluent. VUV also reduced 7% more ammonia nitrogen(NH+4–N), 17%more nitrite nitrogen(NO-2–N), and 18% more total nitrogen(TN) than UV, producing 35%less nitrite nitrogen(NO-3–N) as a result. In conclusion, UV irradiation was better in improving the biodegradability of coking wastewater, while VUV was more effective at photolyzing the residual organic compounds and inorganic N-species in the bio-treated effluent.
基金financially supported by the Fundamental Research Funds for the Central Universities and Science(No.2011ZZ0010)the Technology Innovation Project of Guangdong Provincial Department of Education(No.2013KJCX0014)
文摘Semi-solid powder rolling is a strip manufacturing process, which combines powder rolling with semi-solid rolling in one step to prepare high-performance metallic strips. A total of 7050 aluminum alloy strips were prepared by semi-solid powder rolling and then used to study the post-treatment process and evaluate qualities of post-treated strips.Three post-treatment processes involving sintering, pre-sintering—cold deformation—sintering, and hot rolling were used to process the semi-solid powder rolled strips. The results show that both swelling of pores and densification occur during solid-state sintering while microhardness increases. The decrease in density is due to that the swelling of pores has a larger effect on the density change than that of densification. The relative density reaches 92.6% with the maximum microhardness of 300 HV after ‘‘pre-sintering—cold deformation—sintering'' process. High microhardness is due to the ultrafine secondary particles uniformly distributed within the grains. The microhardness and relative density of a hot rolled strip are 176 HV and 99%, respectively, and the secondary particles disappear. Occurrence of recrystallization in these three post-treatment processes makes the grains finer.
