Rates of photosynthesis, tolerance to photooxidative stress, and senescence are all important physiological factors that affect plant development and thus agricultural productivity. GRAS proteins play essential roles ...Rates of photosynthesis, tolerance to photooxidative stress, and senescence are all important physiological factors that affect plant development and thus agricultural productivity. GRAS proteins play essential roles in plant growth and development as well as in plant responses to biotic and abiotic stresses. So far few GRAS genes in wheat （Triticum aestivum L.） have been characterized. A previous transcriptome analysis indicated that the expression of a GRAS gene （TaSCL14） was induced by high-light stress in Xiaoyan 54 （XY54）, a common wheat cultivar with strong tolerance to high-light stress. In this study, TaSCL14 gene was isolated from XY54 and mapped on chromosome 4A. TaSCL14 was expressed in various wheat organs, with high levels in stems and roots. Our results confirmed that TaSCL14 expression was indeed responsive to high-light stress. Barley stripe mosaic virus （BSMV）-based virus-induced gene silencing （VIGS） of TaSCL14 in wheat was performed to help characterize its potential functions. Silencing of TaSCL14 resulted in inhibited plant growth, decreased photosynthetic capacity, and reduced tolerance to photooxidative stress. In addition, silencing of TaSCL14 in wheat promoted leaf senescence induced by darkness. These results suggest that TaSCL14 may act as a multifunctional regulator involved in plant growth, photosynthesis, tolerance to photooxidative stress, and senescence.展开更多
Results of triplet-triplet energy transfer from biacetyl to OPVs and OPV tripiet state quenching by 1, 4-diazabicyclo[2.2.2] octane (DABCO) suggested that tripiet state of oligophenylenevinylenes(OPVs) directly takes ...Results of triplet-triplet energy transfer from biacetyl to OPVs and OPV tripiet state quenching by 1, 4-diazabicyclo[2.2.2] octane (DABCO) suggested that tripiet state of oligophenylenevinylenes(OPVs) directly takes part in their photooxidative degradation instead of just generating singlet oxygen.展开更多
Into the photooxidation process, several factors such as pH, time of irradiation, dose of UV light, lamp power, contaminant concentration, turbidity of the solution and the presence of salts can interfere with the pho...Into the photooxidation process, several factors such as pH, time of irradiation, dose of UV light, lamp power, contaminant concentration, turbidity of the solution and the presence of salts can interfere with the photodegradation of pollutants. This research aims to evaluate the influence of salts： NaCl, MgCl2, CaCI2, BaC12, CuCl2, Na2SO4, MgSO4, MnSO4, FeSO4, CuSO4, Na3PO4, K2CrO4 and K2Cr207 in concentrations of 0.0005 M, 0.005 M and 0.05 M during photodegradation of aqueous solution of 59.5 mg/L of nitrobenzene at a pH of 2.5. It was observed that the presence of salts such as CuCI2, CuSO4, FeSO4, K2CrO4 and K2Cr207 interfere negatively in the system UV/H202 applied for degradation of nitrobenzene; possibly by oxidation of Fe2＋ to Fe3＋ and Cu＋ to Cu2＋ in the Cr case, due to the difficulty of transforming the Cr6＋ to Cr3＋ or because these solutions have color and act as radiation absorbing filter.展开更多
This study was intended to determine the effectiveness of ascorbic acid microemulsion for inhibiting photooxidation of virgin coconut oil （VCO）. The ascorbic acid microemulsion was prepared by mixing ascorbic acid, ...This study was intended to determine the effectiveness of ascorbic acid microemulsion for inhibiting photooxidation of virgin coconut oil （VCO）. The ascorbic acid microemulsion was prepared by mixing ascorbic acid, deionized water, surfactant mixture, and VCO as continuous phase. Ascorbic acid microemulsion at 50, 100, 150, 200, or 250 ppm was dispersed into VCO. The same level of ascorbyl palmitate, TBHQ （tertiary butylhydroquinone）, and BHA （butylated hidroxyanisole） were added into VCO and used for comparison. All of these samples were subsequently subjected to photooxidation under fluorescent light exposure （4,000 lux） for up to 8 hours at room temperature （30 ~ 1 ~C）. Peroxide values and p-anisidine values of photooxidized samples were measured at 1 hour interval. The result indicated that at the level of 250 ppm, ascorbic acid which was included into the microemulsion system effectively inhibited photooxidation of VCO in comparison with the other antioxidants. This study confirmed that a highly hydrophilic singlet oxygen quencher （SOQ） such as ascorbic acid can be successfully incorporated into the microemulsion system and the addition of ascorbic acid microemulsion effectively inhibited photooxidation of VCO during storage under fluorescent light.展开更多
The tea plant cultivar‘Zhonghuang 2'(ZH2)possesses albino-induced yellow leaves that contain low levels of catechins but high contents of amino acids.However,the molecular mechanism underlying the yellow leaf phe...The tea plant cultivar‘Zhonghuang 2'(ZH2)possesses albino-induced yellow leaves that contain low levels of catechins but high contents of amino acids.However,the molecular mechanism underlying the yellow leaf phenotype of ZH2 has not been elucidated clearly.In the current research,the yellow shoots(ZH2-Y)and naturally converted green shoots(ZH2-G)of ZH2 were studied using metabolic and proteomic profiling for a better understanding of the mechanism underlying phenotype formation.In total,107 differentially changed metabolites(DCMs)were identified from the GC-MS-based metabolomics,and 189 differentially accumulated proteins(DAPs)were identified from the tandem mass tag(TMT)-based quantitative proteomics.Subsequently,integrated analysis revealed that‘porphyrin and chlorophyll metabolism',‘carbon fixation in photosynthetic organisms',and‘phenylpropanoid biosynthesis'pathways were commonly enriched for DAPs and DCMs.We further found that the inhibition of chlorophyll biosynthesis,the deficiency of photosynthetic proteins and the imbalance of the ROS-scavenging system were the crucial reasons responsible for the chlorosis,chloroplast abnormality and photooxidative damage of ZH2 leaves.Altogether,our research combines metabolomics and proteomics approaches to uncover the molecular mechanism leading to the yellow leaf phenotype of tea plants.展开更多
Photocatalysis has emerged as an effective approach to sustainably convert biomass into value-added products.CoSe_(2)is a promising nonprecious,efficient cocatalyst for photooxidation,which can facilitate the separati...Photocatalysis has emerged as an effective approach to sustainably convert biomass into value-added products.CoSe_(2)is a promising nonprecious,efficient cocatalyst for photooxidation,which can facilitate the separation of photogenerated electron–holes,increase the reaction rates,and enhance photocatalytic efficiency.In this work,we synthesized a stable and efficient photocatalysis system of CoSe_(2)/g-C_(3)N_(4)through attaching CoSe_(2)on g-C_(3)N_(4)sheets,with a yield of 50.12%for the selective photooxidation of xylose to xylonic acid.Under light illumination,the photogenerated electrons were prone to migrating from g-C_(3)N_(4)to CoSe_(2)due to the higher work function of CoSe_(2),resulting in the accelerated separation of photogenerated electron–holes and the promoted photooxidation.Herein,this study reveals the unique function of CoSe_(2),which can significantly promote oxygen adsorption,work as an electron sink and accelerate the generation of ·O_(2)^(-),thereby improving the selectivity toward xylonic acid over other by-products.This work provides useful insights into the design of selective photocatalysts by engineering g-C_(3)N_(4)for biomass high-value utilization.展开更多
It is highly challenging to precisely compare the impacts of anthropogenic pollutants on the photooxidation of isomeric volatile organic compounds with respect to molecular compositions and particle number/mass concen...It is highly challenging to precisely compare the impacts of anthropogenic pollutants on the photooxidation of isomeric volatile organic compounds with respect to molecular compositions and particle number/mass concentrations of secondary organic aerosols(SOAs).In this study,we conducted a series of well-defined indoor chamber experiments to compare the effects of NO_(x)(NO and NO_(2))on the photooxidation of isomeric monoterpenes ofβ-pinene and limonene.For the photooxidation ofβ-pinene with NO_(x),the increase of the initial concentrations of NO([NO]_(0))shows a monotonous suppression of the particle mass concentration,whereas the increase of[NO_(2)]_(0) shows a monotonous enhancement of the particle mass concentration.For the photooxidation of limonene with NO_(x),the increase of[NO]_(0) exhibits a monotonous suppression of the particle mass concentration,whereas the increase of[NO_(2)]_(0) shows a parabolic trend of the particle mass concentration.Utilizing a newly developed vacuum ultraviolet free electron laser(VUV-FEL),the online threshold photoionization mass spectrometry reveals a series of novel compounds at molecular weight(MW)=232 and 306 for theβ-pinene+NO_(x) system and MW=187,261,280,and 306 for the limonene+NO_(x) system.The molecular structures and formation pathways of these species were inferred,which led to the prediction of the diversity and difference of SOA products(i.e.,ester and peroxide accretion products)formed from different monoterpene precursors.To improve the predictions of future air quality,it is recommended that climate models should incorporate the NO_(x)-driven diurnal photooxidation of monoterpenes for SOA formation mechanisms.展开更多
Direct conversion of methane into C1 oxygenates under mild condition with high selectivity is a desired goal in the field of energy and chemistry.But it still remains a great challenge due to the intrinsic inertness o...Direct conversion of methane into C1 oxygenates under mild condition with high selectivity is a desired goal in the field of energy and chemistry.But it still remains a great challenge due to the intrinsic inertness of methane originating from strong C-H bonds(104 kcal/mol),low solubility in the solvent,and poor selectivity.Herein,we present a direct single-step conversion of methane to formic acid(HCOOH)using molecular oxygen(O_(2)) as the oxidant under gentle conditions on a decatungstate-doped porous cerium metal-organic framework(Ce-MOF),W_(10)@Ce-bpdc.The HCOOH yield of W_(10)@Ce-bpdc-2 was 155μmol/gcatat room temperature in 12 h.The process and mechanism of conversion of methane to HCOOH was revealed by spectroscopic characteristics and controlled experiments.In the presence of light,O_(2)was converted to H_(2)O_(2)by catalyst and then to·OH radicals in solution,which interact with methane and undergo intermediates to produce HCOOH.Our experiment provides a new way to catalyze methane in combination with MOF and polyoxometalates(POMs).展开更多
Elucidating the effects of anthropogenic pollutants on the photooxidation of biogenic volatile organic compounds is crucial to understanding the fundamental mechanisms of secondary organic aerosol(SOA)formation.Here,t...Elucidating the effects of anthropogenic pollutants on the photooxidation of biogenic volatile organic compounds is crucial to understanding the fundamental mechanisms of secondary organic aerosol(SOA)formation.Here,the impacts of NO_(2)and SO_(2)on SOA formation from the photooxidation of a representative monoterpene,β-pinene,were investigated by a number of laboratory studies.The results indicated NO_(2)enhanced the SOA mass concentrations and particle number concentrations under both low and highβ-pinene conditions.This could be rationalized that the increased O_(3)concentrations upon the NO_(x)photolysis was helpful for the generation of more amounts of O_(3)-oxidized products,which accelerated the SOA nucleation and growth.Combing with NO_(2),the promotion of the SOA yield by SO_(2)was mainly reflected in the increase of mass concentration,which might be due to the elimination of the newly formed particles by the initially formed particles.The observed low oxidation degree of SOA might be attributed to the fast growth of SOA,resulting in the uptake of less oxygenated gas-phase species onto the particle phase.The present findings have important implications for SOA formation affected by anthropogenic–biogenic interactions in the ambient atmosphere.展开更多
In this study,diodo boron dipyrromethene(BODIPY)is employed a8 the energy donor and 3,4,9,10-perylene tetracarboxylic dianhydride(PDA)as the energy acceptor,enabling the synthesis of two new compounds:a BODIPY-perylen...In this study,diodo boron dipyrromethene(BODIPY)is employed a8 the energy donor and 3,4,9,10-perylene tetracarboxylic dianhydride(PDA)as the energy acceptor,enabling the synthesis of two new compounds:a BODIPY-perylene dyad named P1,and a triad named P2.To investigate the impact of the energy donor on the photophysical processes of the system,P1 comprises one diodo-BODIPY unit and one PDA unit,whereas P2 contains two diodo-BODIPY moieties and one PDA unit.Due to the good spectral complementarity between diiodo-BODIPY and PDA,these two compounds exhibit excellent light-harvesting capabilities in the 400-620 nm range.Steady-state fluorescence spectra demonstrate that when preferentially exciting the diodo-BODIPY moiety,it can effectively transfer energy to PDA;when selectively exciting the PDA moiety,quenching of PDA fluorescence is observed in both P1 and P2.Nanosecond transient absorption results show that both compounds can efficiently generate triplet excited states,which are located on the PDA part.The lifetimes of the triplet states for these two compounds are 103 and 89μs,respectively,significantly longer than that of diiodo-BODIPY.The results from the photooxidation experiments reveal that both P1 and P2 demonstrate good photostability and photooxidation capabilities,with P2 showing superior photooxidative efficiency.The photooxidation rate constant for P2 is 1.3 times that of P1,and its singlet oxygen quantum yield is 1.6 times that of P1.The results obtained here offer valuable insights for designing new photosensitizers.展开更多
Biotherapeutic's higher order structure(HOS)is a critical determinant of its functional properties and conformational relevance.Here,we evaluated two covalent labeling methods:diethylpyrocarbonate(DEPC)-labeling a...Biotherapeutic's higher order structure(HOS)is a critical determinant of its functional properties and conformational relevance.Here,we evaluated two covalent labeling methods:diethylpyrocarbonate(DEPC)-labeling and fast photooxidation of proteins(FPOP),in conjunction with mass spectrometry(MS),to investigate structural modifications for the new class of immuno-oncological therapy known as bispecific antigen-binding biotherapeutics(BABB).The evaluated techniques unveiled subtle structural changes occurring at the amino acid residue level within the antigen-binding domain under both native and thermal stress conditions,which cannot be detected by conventional biophysical techniques,e.g.,near-ultraviolet circular dichroism(NUV-CD).The determined variations in labeling uptake under native and stress conditions,corroborated by binding assays,shed light on the binding effect,and highlighted the potential of covalent-labeling methods to effectively monitor conformational changes that ultimately influence the product quality.Our study provides a foundation for implementing the developed techniques in elucidating the inherent structural characteristics of novel therapeutics and their conformational stability.展开更多
Benzaldehyde(BnCHO)is a key component in dye production and a fundamental substance in the fine chemical sector,especially for making medicines and flavorings.Under ambient conditions,the synthesis of BnCHO through th...Benzaldehyde(BnCHO)is a key component in dye production and a fundamental substance in the fine chemical sector,especially for making medicines and flavorings.Under ambient conditions,the synthesis of BnCHO through the photo-oxidation of benzyl alcohol(BnOH)demonstrates significant application potential in fine chemical synthesis.Herein,we anchored different metal cations(M=Fe,Co,Cu,and Zn)into monolacunary polyoxometalate(POM)[SiW_(11)O_(39)]^(8-)(SiW)to form single-metal substituted-POMs(MSiWs).Furthermore,we have successfully dispersed these POMs uniformly onto polymeric carbon nitride nanosheets(CN).For BnOH photooxidation without adding extra oxidants such as H_(2)O_(2),the FeSiW/CN-7 exhibited excellent photocatalytic performance with the conversion of BnOH nearly 69.17%and a BnCHO yield of 532.13 mmol·g^(-1)within 12 h.The photo-oxidation performance of BnOH is 76 and 5 times higher than that of single CN and FeSiW,respectively.This catalytic system can maintain a high catalytic efficiency after 5 cycles,indicating that FeSiW/CN possesses high catalytic stability.The results suggest that the designed POM-based single-atom catalyst FeSiW/CN is a promising candidate for the preparation of BnCHO through photooxidation under mild conditions.展开更多
With indica ( Oryza sativa L.) hybrid Shanyou 63 as control, the hybrid rice varieties including Peiai 64S/E32, Peiai 64S/9311, X07S/Zihui 100, Guangyou 881 and japonica 9516 were used to study changes of chlorophyll ...With indica ( Oryza sativa L.) hybrid Shanyou 63 as control, the hybrid rice varieties including Peiai 64S/E32, Peiai 64S/9311, X07S/Zihui 100, Guangyou 881 and japonica 9516 were used to study changes of chlorophyll content, photosynthetic response to light intensity and temperature, chlorophyll fluorescence characteristics and membrane lipid peroxidation in their flag leaves at the late stage of development under natural conditions in Nanjing. The results were as follows:. primary photochemical efficiency of PS II ( F-v / F-m), quantum yield of linear electron transport of PS II (phi(PSII)), electron transfer rate (ETR) in these rice varieties decreased with their decrease of chlorophyll content during this period. This kind of impediment to energy conversion induced the transfer of excessive energy to the reducing side of PS I, hence the accumulation of O-2(radical anion) and peroxidation of membrane lipid, and resulting in the accumulation of malondialdehyde (MDA), that is the destroys of photosynthetic pigments and membranes and the consequent, premature senescence. This phenomenon is variable conspicuously in different rice varieties. Under natural condition in Nanjing, F-v/F-m, phi(PSII), ETR and quenching coefficient ( qP) in japonica 9516 tolerant to photooxidation decreased less and the conversion capacity of light energy was stable, premature senescence was unlikely, and consequently the seed-setting rate was higher. While F-v/F-m, phi(PSII), ETR and photochemical qP in Shanyou 63 sensitive to photooxidation decreased more and therefore premature senescence was easy to happen, thus the seed-setting rate and yield were all reduced. The tolerance to photooxidation and premature senescence in other hybrids derived from typical two line or three line crossing laid in the middle. From the rice breeding for super-high-yield, on the basis of the good plant-type of current rice, considering both hybrid vigor and the prevention premature senescence, it would be a notable strategy to use japonica maternal line or maternal. lines with some japonica genotype as the sterile lines in rice breeding.展开更多
Thirty genotypes from rice germplasm were identified under photooxidation and shading condition and divided into four basic types : (1) cultivars tolerant to both photooxidation and shading, (2) cultivars tolerant to...Thirty genotypes from rice germplasm were identified under photooxidation and shading condition and divided into four basic types : (1) cultivars tolerant to both photooxidation and shading, (2) cultivars tolerant to photooxidation but sensitive to shading, (3) cultivars tolerant to shading but sensitive to photooxidation, and (4) cultivars sensitive to photooxidation and shading. A comparative study of photosynthetic characteristics of a cultivar (cv. Wuyujing 3) that is tolerant and a cultivar (cv. Xiangxian) that is sensitive to both photoinhibition and shading showed that the photochemical efficiency of PSⅡ ( F v/F m ) and the content of PSⅡ_D1 protein in the tolerant cultivar “Wuyujing 3” decreased less under photoinhibition conditions as compared with “Xiangxian”. Under photooxidation conditions, superoxide dismutase was induced rapidly to a higher level and the active oxygen O - built up to a lower level in “Wuyujing 3” than in “Xiangxian”. At the same time, the photosynthetic rate decreased by 23% in “Wuyujing 3” vs. 64% in “Xiangxian”. Shading (20% natural light) during the booting stage caused only small decreases (7%-13%) in RuBisCO activity and the photosynthetic rate in “Wuyujing 3” but showed marked decreases (57%-64%) in “Xiangxian” which corresponded to the decreases in grain yield in the two cultivars (38% and 73%, respectively). The correlation analysis showed that the tolerance to photooxidation is mainly related to PSⅡ_D1 and that to shading is mainly related to RuBisCO activity. This study provided a simple and effective screening method and physiological basis for crop breeding in enhancing tolerance to both high and low radiation.展开更多
Using various high-yield rices (Oryza sativa L.) such as japonica cultivar 9516, two parental line hybrid rice between subspecies with more japonica element Peiai 64/E32, Liangyoupeijiu (Peiai 64/9311), and indica hyb...Using various high-yield rices (Oryza sativa L.) such as japonica cultivar 9516, two parental line hybrid rice between subspecies with more japonica element Peiai 64/E32, Liangyoupeijiu (Peiai 64/9311), and indica hybrid rices X07S/Zihui 100, Gangyou 881, Shanyou 63 as the materials, the characteristics of chlorophyll fluorescence and membrane-lipid peroxidation of detached leaves at booting stage under photooxidation conditions were studied. In comparison with indica hybrid rice, after the photooxidation treatment, the primary photochemical efficiency of PS II (F-v/F-m), quantum yield of linear electron transport of PS II (Phi(PSII)) and photochemical quenching coefficient (qP) in japonica cultivar and hybrid rice with japonica decreased less. This indicated that high-yield rice with japonica was able to maintain higher capability of light energy conversion, resulting in the alleviation of photoinhibition. Meanwhile, the higher activities of protective enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) led to the less accumulation of endogenous active oxygen (O-(2)(radical anion), H2O2) and less content of the malondialdehyde (MDA) and the less decline of chlorophyll and protein contents, indicating a stronger tolerance to photooxidation. The changes in contents of chlorophyll and protein among various nee cultivars during photooxidation treatment were consistent with the decline of chlorophyll content from heading stage to maturation stage under natural conditions. Statistical analysis showed that there was a significant correlation between the indexes of tolerance to photooxidation and the rate of seed setting, implying that the cultivar tolerated to photooxidation had higher resistance to early aging of leaf. These results suggested that from a view of superhigh-yield breeding, considering both the utilization of heterosis and the resistance to early aging of leaf, introduction of japonica element tolerating to photooxidation into the rice sterile line (maternal plant) is a breeding strategy worthy to pay great attention to.展开更多
The switch from C-3 to CAM pathway was induced by water stress in a C-3/CAM intermediate plant Sedum spectabile Boreau. Typical CAM criteria were observed upon 15 d of withholding water. Leaf delta(13)C value (-%) and...The switch from C-3 to CAM pathway was induced by water stress in a C-3/CAM intermediate plant Sedum spectabile Boreau. Typical CAM criteria were observed upon 15 d of withholding water. Leaf delta(13)C value (-%) and water content showed a linear correlation fashion. Chlorophyll fluorescence parameters and antioxidative capacity were altered by water stress. Phi(PSII) and q(P) were reduced by 50% and 34% of the control, respectively, while NPQ rose ca. 180%. SOD activity and ability to scavenge DPPH. free radical went down but membrane permeability changed slightly. However, when an additional photooxidation by MV with high PPFD was carried out with leaf discs from watered (C-3 mode) and drought plants (CAM mode), q(P) and Phi(PSII) in leaves at induced CAM mode stage continuously decreased to a very low level. High 1 - q(P) value (0.86) and 1 - q(P)/NPQ ratio (>1) indicated the presence of high reduction state and unbalance of light energy budget. Together with the marked loss of membrane integral, it was evidenced that photooxidative damage was more serious in the induced CAM mode than in the C-3 mode. No advantage of photooxidation tolerance was found at the induced CAM expression stage of the facultative CAM plant, as compared with its C-3 mode stage, and also with the constitutive CAM plants reported previously. The differences in photooxidation sensitivity between the inducible CAM expressing plant and the constitutive CAM plant were discussed.展开更多
Six kinds of cerium carboxylate (CeCar(3)) and rare earth carboxylate (RECar(3), RE=La+Ce+Pr) complexes were synthesized, and the compositions and characters of these complexes were studied by elementary analysis, the...Six kinds of cerium carboxylate (CeCar(3)) and rare earth carboxylate (RECar(3), RE=La+Ce+Pr) complexes were synthesized, and the compositions and characters of these complexes were studied by elementary analysis, thermo-gravimetric and differential thermal analysis (TG-DTA), infrared (IR) spectroscopy and ultra violet (UV) spectroscopy. The carbonyl indexes (CI) of law density polyethylene (LDPE) films containing CeCar(3) or RECar(3) during UV photooxidation were determined by IR spectroscopy. The effects of CeCar(3) or RECar(3) on the UV photooxidation rates, viscosity and average molecular weights (M(n)) of LDPE films were studied by using CI, and their mechanisms in sensitizing photooxidation degradation of LDPE films are discussed. Results show that the lifetime of LDPE films can be controlled by adding 0.1 wt%similar to 0.3 wt% CeCar(3) complexes to LDPE films.展开更多
The crystal phase, morphology and facet significantly influence the catalytic and photocat- alytic activity of TiO2. In view of optimizing the performance of catalysts, extensive efforts have been devoted to designing...The crystal phase, morphology and facet significantly influence the catalytic and photocat- alytic activity of TiO2. In view of optimizing the performance of catalysts, extensive efforts have been devoted to designing new sophisticate TiO2 structures with desired facet exposure, necessitating the understanding of chemical properties of individual surface. In this work, we have examined the photooxidation of methanol on TiO 2 （011）- （ 2 × 1 ） and TiO 2 （110） - （1 ×1） by two-photon photoemission spectroscopy （2PPE）. An excited state at 2.5 eV above the Fermi level （EF） on methanol covered （011） and （110） interface has been detected. The excited state is an indicator of reduction of TiO2 interface. Irradiation dependence of the excited resonance signal during the photochemistry of methanol on TiO2（011）-（2×1） and TiO2（110）-（1× 1） is ascribed to the interface reduction by producing surface hydroxyls. The reaction rate of photooxidation of methanol on TiO2（110）-（1× 1） is about 11.4 times faster than that on TiO2（011）-（2×1）, which is tentatively explained by the difference in the surface atomic configuration. This work not only provides a detailed characterization of the electronic structure of methanol/TiO2 interface by 2PPE, but also shows the importance of the surface structure in the photoreactivity on TiO2.展开更多
Hydroxyl radical （.OH）-initiated photooxidation reaction of toluene was carried out in a self-made smog chamber. Four individual seed aerosols such as ammonium sulfate, ammonium nitrate, sodium silicate and calcium ...Hydroxyl radical （.OH）-initiated photooxidation reaction of toluene was carried out in a self-made smog chamber. Four individual seed aerosols such as ammonium sulfate, ammonium nitrate, sodium silicate and calcium chloride, were introduced into the chamber to assess their influence on the growth of secondary organic aerosols （SOA）. It was found that the low concentration of seed aerosols might lead to high concentration of SOA particles. Seed aerosols would promote rates of SOA formation at the start of the reaction and inhibit its formation rate with prolonging the reaction time. In the case of ca. 9000 pt/cm^3 seed aerosol load, the addition of sodium silicate induced a same effect on the SOA formation as ammonium nitrate. The influence of the four individual seed aerosols on the generation of SOA decreased in the order of calcium chloride〉sodium silicate and ammonium nitrate〉ammonium sulfate.展开更多
基金financially supported by the National Natural Science Foundation of China(No.31371609)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA08010403)the National Key Basic Research Program(No.2009CB118506)
文摘Rates of photosynthesis, tolerance to photooxidative stress, and senescence are all important physiological factors that affect plant development and thus agricultural productivity. GRAS proteins play essential roles in plant growth and development as well as in plant responses to biotic and abiotic stresses. So far few GRAS genes in wheat （Triticum aestivum L.） have been characterized. A previous transcriptome analysis indicated that the expression of a GRAS gene （TaSCL14） was induced by high-light stress in Xiaoyan 54 （XY54）, a common wheat cultivar with strong tolerance to high-light stress. In this study, TaSCL14 gene was isolated from XY54 and mapped on chromosome 4A. TaSCL14 was expressed in various wheat organs, with high levels in stems and roots. Our results confirmed that TaSCL14 expression was indeed responsive to high-light stress. Barley stripe mosaic virus （BSMV）-based virus-induced gene silencing （VIGS） of TaSCL14 in wheat was performed to help characterize its potential functions. Silencing of TaSCL14 resulted in inhibited plant growth, decreased photosynthetic capacity, and reduced tolerance to photooxidative stress. In addition, silencing of TaSCL14 in wheat promoted leaf senescence induced by darkness. These results suggest that TaSCL14 may act as a multifunctional regulator involved in plant growth, photosynthesis, tolerance to photooxidative stress, and senescence.
文摘Results of triplet-triplet energy transfer from biacetyl to OPVs and OPV tripiet state quenching by 1, 4-diazabicyclo[2.2.2] octane (DABCO) suggested that tripiet state of oligophenylenevinylenes(OPVs) directly takes part in their photooxidative degradation instead of just generating singlet oxygen.
文摘Into the photooxidation process, several factors such as pH, time of irradiation, dose of UV light, lamp power, contaminant concentration, turbidity of the solution and the presence of salts can interfere with the photodegradation of pollutants. This research aims to evaluate the influence of salts： NaCl, MgCl2, CaCI2, BaC12, CuCl2, Na2SO4, MgSO4, MnSO4, FeSO4, CuSO4, Na3PO4, K2CrO4 and K2Cr207 in concentrations of 0.0005 M, 0.005 M and 0.05 M during photodegradation of aqueous solution of 59.5 mg/L of nitrobenzene at a pH of 2.5. It was observed that the presence of salts such as CuCI2, CuSO4, FeSO4, K2CrO4 and K2Cr207 interfere negatively in the system UV/H202 applied for degradation of nitrobenzene; possibly by oxidation of Fe2＋ to Fe3＋ and Cu＋ to Cu2＋ in the Cr case, due to the difficulty of transforming the Cr6＋ to Cr3＋ or because these solutions have color and act as radiation absorbing filter.
文摘This study was intended to determine the effectiveness of ascorbic acid microemulsion for inhibiting photooxidation of virgin coconut oil （VCO）. The ascorbic acid microemulsion was prepared by mixing ascorbic acid, deionized water, surfactant mixture, and VCO as continuous phase. Ascorbic acid microemulsion at 50, 100, 150, 200, or 250 ppm was dispersed into VCO. The same level of ascorbyl palmitate, TBHQ （tertiary butylhydroquinone）, and BHA （butylated hidroxyanisole） were added into VCO and used for comparison. All of these samples were subsequently subjected to photooxidation under fluorescent light exposure （4,000 lux） for up to 8 hours at room temperature （30 ~ 1 ~C）. Peroxide values and p-anisidine values of photooxidized samples were measured at 1 hour interval. The result indicated that at the level of 250 ppm, ascorbic acid which was included into the microemulsion system effectively inhibited photooxidation of VCO in comparison with the other antioxidants. This study confirmed that a highly hydrophilic singlet oxygen quencher （SOQ） such as ascorbic acid can be successfully incorporated into the microemulsion system and the addition of ascorbic acid microemulsion effectively inhibited photooxidation of VCO during storage under fluorescent light.
基金supported by the Project for Collaborative Promotion of Agricultural Major Technology of Zhejiang Province(Grant No.2022XTTGCY01-02)the National Natural Science Foundation of China(Grant Nos.31700615,32172633)+1 种基金the China Agriculture Research System of MOF and MARA(Grant No.CARS19-01A)the Special Project of Zhejiang Province(Grant No.2020R52036)。
文摘The tea plant cultivar‘Zhonghuang 2'(ZH2)possesses albino-induced yellow leaves that contain low levels of catechins but high contents of amino acids.However,the molecular mechanism underlying the yellow leaf phenotype of ZH2 has not been elucidated clearly.In the current research,the yellow shoots(ZH2-Y)and naturally converted green shoots(ZH2-G)of ZH2 were studied using metabolic and proteomic profiling for a better understanding of the mechanism underlying phenotype formation.In total,107 differentially changed metabolites(DCMs)were identified from the GC-MS-based metabolomics,and 189 differentially accumulated proteins(DAPs)were identified from the tandem mass tag(TMT)-based quantitative proteomics.Subsequently,integrated analysis revealed that‘porphyrin and chlorophyll metabolism',‘carbon fixation in photosynthetic organisms',and‘phenylpropanoid biosynthesis'pathways were commonly enriched for DAPs and DCMs.We further found that the inhibition of chlorophyll biosynthesis,the deficiency of photosynthetic proteins and the imbalance of the ROS-scavenging system were the crucial reasons responsible for the chlorosis,chloroplast abnormality and photooxidative damage of ZH2 leaves.Altogether,our research combines metabolomics and proteomics approaches to uncover the molecular mechanism leading to the yellow leaf phenotype of tea plants.
基金financial support by National Key Research and Development Project(Grant No.2023YFE0109600)Guangzhou Key Research and Development Program(Grant No.2023B03J1330)+5 种基金National Program for Support of Topnotch Young Professionals(Grant No.x2qsA4210090)Guangzhou Basic and Applied Basic Research Foundation(Grant No.2024A04J3413)National Natural Science Foundation of China(Grant No.32201499)State Key Laboratory of Pulp and Paper Engineering(Grant Nos.2023PY01 and 202215)Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2023A1515012519 and 2023B1515040013)China Postdoctoral Science Foundation(Grant No.2023M732021).
文摘Photocatalysis has emerged as an effective approach to sustainably convert biomass into value-added products.CoSe_(2)is a promising nonprecious,efficient cocatalyst for photooxidation,which can facilitate the separation of photogenerated electron–holes,increase the reaction rates,and enhance photocatalytic efficiency.In this work,we synthesized a stable and efficient photocatalysis system of CoSe_(2)/g-C_(3)N_(4)through attaching CoSe_(2)on g-C_(3)N_(4)sheets,with a yield of 50.12%for the selective photooxidation of xylose to xylonic acid.Under light illumination,the photogenerated electrons were prone to migrating from g-C_(3)N_(4)to CoSe_(2)due to the higher work function of CoSe_(2),resulting in the accelerated separation of photogenerated electron–holes and the promoted photooxidation.Herein,this study reveals the unique function of CoSe_(2),which can significantly promote oxygen adsorption,work as an electron sink and accelerate the generation of ·O_(2)^(-),thereby improving the selectivity toward xylonic acid over other by-products.This work provides useful insights into the design of selective photocatalysts by engineering g-C_(3)N_(4)for biomass high-value utilization.
基金supported by the National Natural Science Foundation of China(Nos.22125303,92361302,92061203,22103082,22273101,22288201,and 21327901)the National Key Research and Development Program of China(No.2021YFA1400501)+3 种基金the Innovation Program for Quantum Science and Technology(No.2021ZD0303304)Dalian Institute of Chemical Physics(No.DICPI202437)Chinese Academy of Sciences(No.GJJSTD20220001)the International Partnership Program of CAS(No.121421KYSB20170012)。
文摘It is highly challenging to precisely compare the impacts of anthropogenic pollutants on the photooxidation of isomeric volatile organic compounds with respect to molecular compositions and particle number/mass concentrations of secondary organic aerosols(SOAs).In this study,we conducted a series of well-defined indoor chamber experiments to compare the effects of NO_(x)(NO and NO_(2))on the photooxidation of isomeric monoterpenes ofβ-pinene and limonene.For the photooxidation ofβ-pinene with NO_(x),the increase of the initial concentrations of NO([NO]_(0))shows a monotonous suppression of the particle mass concentration,whereas the increase of[NO_(2)]_(0) shows a monotonous enhancement of the particle mass concentration.For the photooxidation of limonene with NO_(x),the increase of[NO]_(0) exhibits a monotonous suppression of the particle mass concentration,whereas the increase of[NO_(2)]_(0) shows a parabolic trend of the particle mass concentration.Utilizing a newly developed vacuum ultraviolet free electron laser(VUV-FEL),the online threshold photoionization mass spectrometry reveals a series of novel compounds at molecular weight(MW)=232 and 306 for theβ-pinene+NO_(x) system and MW=187,261,280,and 306 for the limonene+NO_(x) system.The molecular structures and formation pathways of these species were inferred,which led to the prediction of the diversity and difference of SOA products(i.e.,ester and peroxide accretion products)formed from different monoterpene precursors.To improve the predictions of future air quality,it is recommended that climate models should incorporate the NO_(x)-driven diurnal photooxidation of monoterpenes for SOA formation mechanisms.
基金supported by the National Natural Science Foundation of China (Nos. 92261118, 92161103, 22071180)。
文摘Direct conversion of methane into C1 oxygenates under mild condition with high selectivity is a desired goal in the field of energy and chemistry.But it still remains a great challenge due to the intrinsic inertness of methane originating from strong C-H bonds(104 kcal/mol),low solubility in the solvent,and poor selectivity.Herein,we present a direct single-step conversion of methane to formic acid(HCOOH)using molecular oxygen(O_(2)) as the oxidant under gentle conditions on a decatungstate-doped porous cerium metal-organic framework(Ce-MOF),W_(10)@Ce-bpdc.The HCOOH yield of W_(10)@Ce-bpdc-2 was 155μmol/gcatat room temperature in 12 h.The process and mechanism of conversion of methane to HCOOH was revealed by spectroscopic characteristics and controlled experiments.In the presence of light,O_(2)was converted to H_(2)O_(2)by catalyst and then to·OH radicals in solution,which interact with methane and undergo intermediates to produce HCOOH.Our experiment provides a new way to catalyze methane in combination with MOF and polyoxometalates(POMs).
基金National Natural Science Foundation of China (Nos.22125303,92061203,and 22288201)the National Key Research and Development Program of China (No.2021YFA1400501)+3 种基金Innovation Program for Quantum Science and Technology (No.2021ZD0303304)Dalian Institute of Chemical Physics (No.DICP DCLS201702)Chinese Academy of Sciences (No.GJJSTD20220001)K.C.Wong Education Foundation (No.GJTD-2018-06)。
文摘Elucidating the effects of anthropogenic pollutants on the photooxidation of biogenic volatile organic compounds is crucial to understanding the fundamental mechanisms of secondary organic aerosol(SOA)formation.Here,the impacts of NO_(2)and SO_(2)on SOA formation from the photooxidation of a representative monoterpene,β-pinene,were investigated by a number of laboratory studies.The results indicated NO_(2)enhanced the SOA mass concentrations and particle number concentrations under both low and highβ-pinene conditions.This could be rationalized that the increased O_(3)concentrations upon the NO_(x)photolysis was helpful for the generation of more amounts of O_(3)-oxidized products,which accelerated the SOA nucleation and growth.Combing with NO_(2),the promotion of the SOA yield by SO_(2)was mainly reflected in the increase of mass concentration,which might be due to the elimination of the newly formed particles by the initially formed particles.The observed low oxidation degree of SOA might be attributed to the fast growth of SOA,resulting in the uptake of less oxygenated gas-phase species onto the particle phase.The present findings have important implications for SOA formation affected by anthropogenic–biogenic interactions in the ambient atmosphere.
基金supported by the Research Project for Outstanding Young People in Universities of Anhui Province(No.2023AH030099)the China Postdoctoral Science Foundation(No.2023M733378)+3 种基金the National Natural Science Foundation of China(No.21702042,No.22305059,No.22103010)the National University Students'Innovation and Entrepreneurship Training Program(No.202311059024)the Anhui Provincial Natural Science Foundation(No.2308085QB59)the Anhui Provincial Excellent Scientific Research and Innovation Team(No.2022AH010096).
文摘In this study,diodo boron dipyrromethene(BODIPY)is employed a8 the energy donor and 3,4,9,10-perylene tetracarboxylic dianhydride(PDA)as the energy acceptor,enabling the synthesis of two new compounds:a BODIPY-perylene dyad named P1,and a triad named P2.To investigate the impact of the energy donor on the photophysical processes of the system,P1 comprises one diodo-BODIPY unit and one PDA unit,whereas P2 contains two diodo-BODIPY moieties and one PDA unit.Due to the good spectral complementarity between diiodo-BODIPY and PDA,these two compounds exhibit excellent light-harvesting capabilities in the 400-620 nm range.Steady-state fluorescence spectra demonstrate that when preferentially exciting the diodo-BODIPY moiety,it can effectively transfer energy to PDA;when selectively exciting the PDA moiety,quenching of PDA fluorescence is observed in both P1 and P2.Nanosecond transient absorption results show that both compounds can efficiently generate triplet excited states,which are located on the PDA part.The lifetimes of the triplet states for these two compounds are 103 and 89μs,respectively,significantly longer than that of diiodo-BODIPY.The results from the photooxidation experiments reveal that both P1 and P2 demonstrate good photostability and photooxidation capabilities,with P2 showing superior photooxidative efficiency.The photooxidation rate constant for P2 is 1.3 times that of P1,and its singlet oxygen quantum yield is 1.6 times that of P1.The results obtained here offer valuable insights for designing new photosensitizers.
基金supported by Amgen Inc.,USA and the National Institutes of Health,USA(Grant Nos.:R01CA218500(ARI)and R35GM136421(ARI))。
文摘Biotherapeutic's higher order structure(HOS)is a critical determinant of its functional properties and conformational relevance.Here,we evaluated two covalent labeling methods:diethylpyrocarbonate(DEPC)-labeling and fast photooxidation of proteins(FPOP),in conjunction with mass spectrometry(MS),to investigate structural modifications for the new class of immuno-oncological therapy known as bispecific antigen-binding biotherapeutics(BABB).The evaluated techniques unveiled subtle structural changes occurring at the amino acid residue level within the antigen-binding domain under both native and thermal stress conditions,which cannot be detected by conventional biophysical techniques,e.g.,near-ultraviolet circular dichroism(NUV-CD).The determined variations in labeling uptake under native and stress conditions,corroborated by binding assays,shed light on the binding effect,and highlighted the potential of covalent-labeling methods to effectively monitor conformational changes that ultimately influence the product quality.Our study provides a foundation for implementing the developed techniques in elucidating the inherent structural characteristics of novel therapeutics and their conformational stability.
基金supported by National Natural Science Foundation of China(22071180)
文摘Benzaldehyde(BnCHO)is a key component in dye production and a fundamental substance in the fine chemical sector,especially for making medicines and flavorings.Under ambient conditions,the synthesis of BnCHO through the photo-oxidation of benzyl alcohol(BnOH)demonstrates significant application potential in fine chemical synthesis.Herein,we anchored different metal cations(M=Fe,Co,Cu,and Zn)into monolacunary polyoxometalate(POM)[SiW_(11)O_(39)]^(8-)(SiW)to form single-metal substituted-POMs(MSiWs).Furthermore,we have successfully dispersed these POMs uniformly onto polymeric carbon nitride nanosheets(CN).For BnOH photooxidation without adding extra oxidants such as H_(2)O_(2),the FeSiW/CN-7 exhibited excellent photocatalytic performance with the conversion of BnOH nearly 69.17%and a BnCHO yield of 532.13 mmol·g^(-1)within 12 h.The photo-oxidation performance of BnOH is 76 and 5 times higher than that of single CN and FeSiW,respectively.This catalytic system can maintain a high catalytic efficiency after 5 cycles,indicating that FeSiW/CN possesses high catalytic stability.The results suggest that the designed POM-based single-atom catalyst FeSiW/CN is a promising candidate for the preparation of BnCHO through photooxidation under mild conditions.
文摘With indica ( Oryza sativa L.) hybrid Shanyou 63 as control, the hybrid rice varieties including Peiai 64S/E32, Peiai 64S/9311, X07S/Zihui 100, Guangyou 881 and japonica 9516 were used to study changes of chlorophyll content, photosynthetic response to light intensity and temperature, chlorophyll fluorescence characteristics and membrane lipid peroxidation in their flag leaves at the late stage of development under natural conditions in Nanjing. The results were as follows:. primary photochemical efficiency of PS II ( F-v / F-m), quantum yield of linear electron transport of PS II (phi(PSII)), electron transfer rate (ETR) in these rice varieties decreased with their decrease of chlorophyll content during this period. This kind of impediment to energy conversion induced the transfer of excessive energy to the reducing side of PS I, hence the accumulation of O-2(radical anion) and peroxidation of membrane lipid, and resulting in the accumulation of malondialdehyde (MDA), that is the destroys of photosynthetic pigments and membranes and the consequent, premature senescence. This phenomenon is variable conspicuously in different rice varieties. Under natural condition in Nanjing, F-v/F-m, phi(PSII), ETR and quenching coefficient ( qP) in japonica 9516 tolerant to photooxidation decreased less and the conversion capacity of light energy was stable, premature senescence was unlikely, and consequently the seed-setting rate was higher. While F-v/F-m, phi(PSII), ETR and photochemical qP in Shanyou 63 sensitive to photooxidation decreased more and therefore premature senescence was easy to happen, thus the seed-setting rate and yield were all reduced. The tolerance to photooxidation and premature senescence in other hybrids derived from typical two line or three line crossing laid in the middle. From the rice breeding for super-high-yield, on the basis of the good plant-type of current rice, considering both hybrid vigor and the prevention premature senescence, it would be a notable strategy to use japonica maternal line or maternal. lines with some japonica genotype as the sterile lines in rice breeding.
文摘Thirty genotypes from rice germplasm were identified under photooxidation and shading condition and divided into four basic types : (1) cultivars tolerant to both photooxidation and shading, (2) cultivars tolerant to photooxidation but sensitive to shading, (3) cultivars tolerant to shading but sensitive to photooxidation, and (4) cultivars sensitive to photooxidation and shading. A comparative study of photosynthetic characteristics of a cultivar (cv. Wuyujing 3) that is tolerant and a cultivar (cv. Xiangxian) that is sensitive to both photoinhibition and shading showed that the photochemical efficiency of PSⅡ ( F v/F m ) and the content of PSⅡ_D1 protein in the tolerant cultivar “Wuyujing 3” decreased less under photoinhibition conditions as compared with “Xiangxian”. Under photooxidation conditions, superoxide dismutase was induced rapidly to a higher level and the active oxygen O - built up to a lower level in “Wuyujing 3” than in “Xiangxian”. At the same time, the photosynthetic rate decreased by 23% in “Wuyujing 3” vs. 64% in “Xiangxian”. Shading (20% natural light) during the booting stage caused only small decreases (7%-13%) in RuBisCO activity and the photosynthetic rate in “Wuyujing 3” but showed marked decreases (57%-64%) in “Xiangxian” which corresponded to the decreases in grain yield in the two cultivars (38% and 73%, respectively). The correlation analysis showed that the tolerance to photooxidation is mainly related to PSⅡ_D1 and that to shading is mainly related to RuBisCO activity. This study provided a simple and effective screening method and physiological basis for crop breeding in enhancing tolerance to both high and low radiation.
文摘Using various high-yield rices (Oryza sativa L.) such as japonica cultivar 9516, two parental line hybrid rice between subspecies with more japonica element Peiai 64/E32, Liangyoupeijiu (Peiai 64/9311), and indica hybrid rices X07S/Zihui 100, Gangyou 881, Shanyou 63 as the materials, the characteristics of chlorophyll fluorescence and membrane-lipid peroxidation of detached leaves at booting stage under photooxidation conditions were studied. In comparison with indica hybrid rice, after the photooxidation treatment, the primary photochemical efficiency of PS II (F-v/F-m), quantum yield of linear electron transport of PS II (Phi(PSII)) and photochemical quenching coefficient (qP) in japonica cultivar and hybrid rice with japonica decreased less. This indicated that high-yield rice with japonica was able to maintain higher capability of light energy conversion, resulting in the alleviation of photoinhibition. Meanwhile, the higher activities of protective enzymes such as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) led to the less accumulation of endogenous active oxygen (O-(2)(radical anion), H2O2) and less content of the malondialdehyde (MDA) and the less decline of chlorophyll and protein contents, indicating a stronger tolerance to photooxidation. The changes in contents of chlorophyll and protein among various nee cultivars during photooxidation treatment were consistent with the decline of chlorophyll content from heading stage to maturation stage under natural conditions. Statistical analysis showed that there was a significant correlation between the indexes of tolerance to photooxidation and the rate of seed setting, implying that the cultivar tolerated to photooxidation had higher resistance to early aging of leaf. These results suggested that from a view of superhigh-yield breeding, considering both the utilization of heterosis and the resistance to early aging of leaf, introduction of japonica element tolerating to photooxidation into the rice sterile line (maternal plant) is a breeding strategy worthy to pay great attention to.
文摘The switch from C-3 to CAM pathway was induced by water stress in a C-3/CAM intermediate plant Sedum spectabile Boreau. Typical CAM criteria were observed upon 15 d of withholding water. Leaf delta(13)C value (-%) and water content showed a linear correlation fashion. Chlorophyll fluorescence parameters and antioxidative capacity were altered by water stress. Phi(PSII) and q(P) were reduced by 50% and 34% of the control, respectively, while NPQ rose ca. 180%. SOD activity and ability to scavenge DPPH. free radical went down but membrane permeability changed slightly. However, when an additional photooxidation by MV with high PPFD was carried out with leaf discs from watered (C-3 mode) and drought plants (CAM mode), q(P) and Phi(PSII) in leaves at induced CAM mode stage continuously decreased to a very low level. High 1 - q(P) value (0.86) and 1 - q(P)/NPQ ratio (>1) indicated the presence of high reduction state and unbalance of light energy budget. Together with the marked loss of membrane integral, it was evidenced that photooxidative damage was more serious in the induced CAM mode than in the C-3 mode. No advantage of photooxidation tolerance was found at the induced CAM expression stage of the facultative CAM plant, as compared with its C-3 mode stage, and also with the constitutive CAM plants reported previously. The differences in photooxidation sensitivity between the inducible CAM expressing plant and the constitutive CAM plant were discussed.
文摘Six kinds of cerium carboxylate (CeCar(3)) and rare earth carboxylate (RECar(3), RE=La+Ce+Pr) complexes were synthesized, and the compositions and characters of these complexes were studied by elementary analysis, thermo-gravimetric and differential thermal analysis (TG-DTA), infrared (IR) spectroscopy and ultra violet (UV) spectroscopy. The carbonyl indexes (CI) of law density polyethylene (LDPE) films containing CeCar(3) or RECar(3) during UV photooxidation were determined by IR spectroscopy. The effects of CeCar(3) or RECar(3) on the UV photooxidation rates, viscosity and average molecular weights (M(n)) of LDPE films were studied by using CI, and their mechanisms in sensitizing photooxidation degradation of LDPE films are discussed. Results show that the lifetime of LDPE films can be controlled by adding 0.1 wt%similar to 0.3 wt% CeCar(3) complexes to LDPE films.
基金This work was supported the Natural Science Foundation of Liaoning Province （No.2015020242）, the National Natural Science Foundation of China （No.21203189 and No.21573225）, and the State Key Laboratory of Molecular Reaction Dynamics （No.ZZ- 2014-02）.
文摘The crystal phase, morphology and facet significantly influence the catalytic and photocat- alytic activity of TiO2. In view of optimizing the performance of catalysts, extensive efforts have been devoted to designing new sophisticate TiO2 structures with desired facet exposure, necessitating the understanding of chemical properties of individual surface. In this work, we have examined the photooxidation of methanol on TiO 2 （011）- （ 2 × 1 ） and TiO 2 （110） - （1 ×1） by two-photon photoemission spectroscopy （2PPE）. An excited state at 2.5 eV above the Fermi level （EF） on methanol covered （011） and （110） interface has been detected. The excited state is an indicator of reduction of TiO2 interface. Irradiation dependence of the excited resonance signal during the photochemistry of methanol on TiO2（011）-（2×1） and TiO2（110）-（1× 1） is ascribed to the interface reduction by producing surface hydroxyls. The reaction rate of photooxidation of methanol on TiO2（110）-（1× 1） is about 11.4 times faster than that on TiO2（011）-（2×1）, which is tentatively explained by the difference in the surface atomic configuration. This work not only provides a detailed characterization of the electronic structure of methanol/TiO2 interface by 2PPE, but also shows the importance of the surface structure in the photoreactivity on TiO2.
基金Project supported by the National Natural Science Foundation of China(No.20477043)the Knowledge Innovation Program of Chinese Academy of Sciences(No.KZCX2-SW-H08).*
文摘Hydroxyl radical （.OH）-initiated photooxidation reaction of toluene was carried out in a self-made smog chamber. Four individual seed aerosols such as ammonium sulfate, ammonium nitrate, sodium silicate and calcium chloride, were introduced into the chamber to assess their influence on the growth of secondary organic aerosols （SOA）. It was found that the low concentration of seed aerosols might lead to high concentration of SOA particles. Seed aerosols would promote rates of SOA formation at the start of the reaction and inhibit its formation rate with prolonging the reaction time. In the case of ca. 9000 pt/cm^3 seed aerosol load, the addition of sodium silicate induced a same effect on the SOA formation as ammonium nitrate. The influence of the four individual seed aerosols on the generation of SOA decreased in the order of calcium chloride〉sodium silicate and ammonium nitrate〉ammonium sulfate.
