平流层臭氧季节变化的动力和光化学作用之比较

1992年到2005年的HALOE资料显示,在臭氧光化损耗中,ClOx和NOx的贡献大小和作用位置有所差异。SOCRATES3模式模拟表明,两半球夏季高纬极区的臭氧减少,主要是NOx的化学贡献;北极春季和南极冬季副极地臭氧的变化,主要是动力输送引起。南、北极春季臭氧减少的化学机制也有所不同,南极春季的臭氧耗损包括极区内ClOx的异相化学作用和副极区NOx的化学作用;北极春季的臭氧耗损主要以NOx和ClOx的气相化学作用为主,其中NOx的作用更大。动力和光化学在臭氧变化中的贡献表明,整个中低平流层及低纬平流层高层的动力输送贡献可达到45%,而高纬平流层中上层,化学作用贡献在65%以上。

激光——生物组织作用效应及机理分析

对激光与生物组织的相互作用及作用效应的机理进行了分类讨论和分析 ,认为激光与生物的相互作用效应与激光的参数、生物组织特性、机体状态以及激光照射时间等密切相关 ,且其相互作用机理的变化多种多样 ,要利用激光治疗和诊断疾病 。

TiO_2 光化自由基对 U937 细胞氧化压迫凋亡研究

ＴｉＯ２纳米超微粒在３００～４００ｎｍ紫外光照激发下所产生的光生电子空穴对具有极强的光催化反应性能，受其光催化作用，大量活性氧类自由基在细胞内累积，形成细胞内氧化压迫并最终导致细胞凋亡．本研究观察分析了ＴｉＯ２超微粒光激发自由基与氧化压迫性细胞凋亡的关系。

用ESR研究纸张中的自由基

书刊纸和新闻纸经紫外线辐照，具有增强的ＥＳＲ信号，其谱线均为无超精细结构的单峰，属高斯型，线宽约为１０×ｌ０－４特斯拉，ｇ值为２．００５。经比较分析，增强的ＥＳＲ信号，主要来自纸张中的木素，其受紫外线辐照，不断产生新的自由基。此方法可以迅速检测纸张所含木素，并可预测纸经长时期日光光化作用的效果。

Photoactivated Activities on Spodoptera litura Cell, Singlet Oxygen and Photostability of Photosensitizers

[Objective ]The aim of this study was to improve the photostability of pho-tosensitizers. [Method] 2,5-Diphenylthiophene and 2,5-dithienylethynylthiophene were synthesized by replacing thiophene rings of α-terthienyl （α-T） with benzene rings. Photoactivated activities on Spodoptera litura （SL） cells, singlet oxygen with UV and photostability of photosensitizers were investigated. [Result] The cytotoxicity of pho-tosensitizer 2,5-diphenylthiophene on SL cells was 0.22 and 0.16 μg/ml after treat-ment for 24 and 48 h, respectively, while that of 2,5-dithienylethynylthiophene on SL cells was 0.06 and 0.04 μg/ml. Singlet oxygen of 2,5-diphenylthiophene and 2,5-dithienylethynylthiophene was 1.047 5, 1.529 4 μg/mmol under UV, respectively. Degradation dynamic equations of 2,5-diphenylthiophene and 2,5-dithienylethynylthio-phene in methanol were Ct= 5.227 1e-0.006 1t, Ct= 5.084 2e-0.097 3t and half life was 111.79, 7.12 h. [Conclusion] Photosensitizer 2,5-diphenylthiophene has high singlet oxygen production ability, and high photoactivated cytotoxicity on SL cells under UV. Moreover, 2,5-diphenylthiophene has overcome the deficiency of photoactivated in-secticides, which is not applied directly in field because it degrades quickly in the environment.

Simulating leaf net CO_2 assimilation rate of C_3 & C_4 plants and its response to environmental factors

Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.

Enhanced photochemical oxidation ability of carbon nitride by π-πstacking interactions with graphene

A one-pot method for the preparation of g-C3N4/reduced graphene oxide（rGO） composite photocatalysts with controllable band structures is presented.The photocatalysts are characterized by Fouirer transform infrared spectroscopy,X-ray diffraction,scanning electron microscope,transmission electron microscope,and Mott-Schottky analysis.The valance band（VB） of g-C3N4 exhibits a noticeable positive shift upon hybridizing with rGO,and thus results in a strong photo-oxidation ability.The g-C3N4/rGO composites show a higher photodegradation activity for 2,4-dichlorophenol（2,4-DCP） and rhodamine B（RhB） under visible light irradiation（λ≥420 ran）.The g-C3N4/rGO-1sample exhibits the highest photocatalytic activity,which is 1.49 and 1.52 times higher than that of bulk g-C3N4 for 2,4-DCP and 1.52 times degradation,respectively.The enhanced photocatalytic activity for g-C3N4 originates from the improved visible light usage,enhanced electronic conductivity and photo-oxidation ability by the formed strong π-π stacking interactions with rGO.

吸收废气的环保砖

一种可吸收废气的环保砖由香港理工大学研制成功，目前正在测试阶段。

Preparation of Nitrogen-doped TiO2 Nanoparticle Catalyst and Its Catalytic Activity under Visible Light

N-doped TiO2 nanoparticle photocatalysts were prepared through a sol-gel procedure using NH4C1 as the nitrogen source and followed by calcination at certain temperature. Systematic studies for the preparation parameters and their impact on the structure and photocatalytic activity under ultraviolet （UV） and visible light irra-diation were carried out. Multiple techniques （XRD, TEM, DRIF, DSC, and XPS） were commanded to characterize the crystal structures and chemical binding of N-doped TiO2. Its photocatalytic activity was examined by the deg- radation of organic compounds. The catalytic activity of the prepared N-doped TiO2 nanoparticles under visible light （λ〉400nm） irradiation is evidenced by the decomposition of 4-chlorophenol, showing that nitrogen atoms in the N-doped TiO2 nanoparticle catalyst are responsible for the visible light catalytic activity. The N-doped TiO2 nanoparticle catalyst prepared with this modified route exhibits higher catalytic activity under UV irradiation in contrast to TiO2 without N-doping. It is suggested that the doped nitrogen here is located at the interstitial site of TiO2 lattice.

Fabrication of highly dispersed platinum-deposited porous g-C_3N_4 by a simple in situ photoreduction strategy and their excellent visible light photocatalytic activity toward aqueous 4-fluorophenol degradation

A series of highly dispersed platinum‐deposited porous g‐C3N4 (Pt/pg‐C3N4) were successfully fabricated by a simple in situ photoreduction strategy using chloroplatinic acid and porous g‐C3N4 as precursors. Porous g‐C3N4 was fabricated by a pretreatment strategy using melamine as a raw material.The morphology, porosity, phase, chemical structure, and optical and electronic properties ofas‐prepared Pt/pg‐C3N4 were characterized. The photocatalytic activity of as‐prepared Pt/pg‐C3N4was preliminarily evaluated by the degradation of aqueous azo dyes methyl orange under visible light irradiation. The as‐prepared Pt/pg‐C3N4 were further applied to the degradation and mineralization of aqueous 4‐fluorophenol. The recyclability of Pt/pg‐C3N4 was evaluated under four consecutive photocatalytic runs.

Simulating leaf net CO2 assimilation rate of C3 & C4 plants and its response to environmental factors

Basic structure and algorithm of leaf mechanism photosynthesis model were described in first part of this study based on former researcher results. Then, considering some environmental factors influencing on leaf photosynthesis, three numerical sensitivity experiments were carried out. We simulated the sing le leaf net CO2 assimilation, which acts as a function of different light, carbo n dioxide and temperature conditions. The relationships between leaf net photosy nthetic rate of C3 and C4 plant with CO2 concentration intercellular, leaf tempe rature, and photosynthetic active radiation (PAR) were presented, respectively. The results show the numerical experiment may indicate the main characteristic o f plant photosynthesis in C3 and C4 plant, and further can be used to integrate with the regional climate model and act as land surface process scheme, and bett er understand the interaction between vegetation and atmosphere.

Simultaneous formation of a C/N-TiO_2 hollow photocatalyst with efficient photocatalytic performance and recyclability

Herein,we report a unique approach towards the preparation of C-modified and N-doped TiO2 hollow spheres(C/N-TiO2).TEM,SEM,and XPS analyses were used to confirm that the carbon and nitrogen co-decorated TiO2 photocatalyst was formed.Carbon-decoration improves the visible-light absorption and speeds up the separation of the photo-generated electron-hole pairs.C/N-TiO2 not only narrows the band gap of TiO2,but also exhibits excellent photocatalytic activity for the degradation of tetracycline and tetracycline hydrochloride.In addition,the C/N-TiO2 photocatalyst shows excellent recyclability for water decontamination,making it a promising candidate to purify aquatic contaminants.

Significant role of carbonate radicals in tetracycline hydrochloride degradation based on solar light-driven TiO2-seashell composites:Removal and transformation pathways

TiO2-seashell composites prepared via a sol-gel method were used to generate carbonate radicals(·CO3–) under solar light irradiation. ·CO3–, a selective radical, was employed to degrade the target tetracycline hydrochloride contaminant. A series of characterizations was carried out to study the structure and composition of the synthesized TiO2-seashell composite. This material exhibits excellent solar light-driven photochemical activity in the decomposition of tetracycline hydrochloride. The possible pathway and mechanism for the photodegradation process were proposed on the basis of high-resolution electrospray ionization time-of-flight mass spectrometry experiments. Finally, we investigated the reusability of the TiO2-seashell composite. This study is expected to provide a new facile pathway for the application of ·CO3– radicals to degrade special organic pollutants in water.

Science Letters:Development of supported boron-doping TiO_2 catalysts by chemical vapor deposition

In this study, supported nonmetal (boron) doping TiO2 coating photocatalysts were prepared by chemical vapor deposition (CVD) to enhance the activity under visible light irradiation and avoid the recovering of TiO2. Boron atoms were successfully doped into the lattice of TiO2 through CVD, as evidenced from XPS analysis. B-doped TiO2 coating catalysts showed drastic and strong absorption in the visible light range with a red shift in the band gap transition. This novel B-TiO2 coating photocatalyst showed higher photocatalytic activity in methyl orange degradation under visible light irradiation than that of the pure TiO2 photocatalyst.

Promotion of activation ability of N vacancies to N2 molecules on sulfur-doped graphitic carbon nitride with outstanding photocatalytic nitrogen fixation ability

Nitrogen vacancies and sulfur co-doped g-C3N4 with outstanding N2 photofixation ability was synthesized via dielectric barrier discharge plasma treatment. X-ray diffraction, ultraviolet–visible spectroscopy, N2 adsorption, scanning electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and temperature-programmed desorption were used to characterize the as-prepared catalyst. The results showed that plasma treatment cannot change the morphology of the as-prepared catalyst but introduces nitrogen vacancies and sulfur into g-C3N4 lattice simultaneously. The as-prepared co-doped g-C3N4 displays an ammonium ion production rate as high as 6.2 mg·L^-1·h^-1·gcat^-1, which is 2.3 and 25.8 times higher than that of individual N-vacancy-doped g-C3N4 and neat g-C3N4, respectively, as well as showing good catalytic stability. Experimental and density functional theory calculation results indicate that, compared with individual N vacancy doping, the introduction of sulfur can promote the activation ability of N vacancies to N2 molecules, leading to promoted N2 photofixation performance.

Complete removal of phenolic contaminants from bismuth-modified TiO2 single-crystal photocatalysts

Exploring low-cost and highly active photocatalysts is very urgent to accomplish complete removal of phenolic contaminants and overcome the limitations of the existing photocatalysts.In this study,we designed and synthesized noble metal-free TiO2 photocatalysts by introducing bismuth nanoparticles as modifiers of a TiO2 single crystal(Bi-SCTiO2).The Bi-SCTiO2 can make full use of the synergistic effect of a small band overlap and low charge carrier density(Bi)with a high conductivity(single crystal),significantly boosting the separation and migration of the photogenerated charge pairs.Therefore,the Bi-SCTiO2 photocatalyst exhibits a significantly enhanced degradation rate(12 times faster)of 4-nitrophenol than a TiO2 single crystal under simulated sunlight irradiation.Notably,the complete removal of phenolic contaminants is achieved in various water matrices,which not only successfully overcomes the incomplete degradation in many reported photocatalytic systems,but also manifests a significant practical potential for sewage disposal.Therefore,this work presents a new insight in designing and constructing noble metal-free decorated semiconductor single-crystal photocatalysts with excellent activity and cyclability.

Preparation of TiO_2-activated carbon complex membranes and their photoelectrocatalytic activity

The experimental process of preparing TiO 2 activated carbon complex membranes with activated carbon powder as main carrier, PTFE as binder and wire netting as matrix is described in detail, and both photo catalysis and photo electro catalysis are measured to study the properties of complex membranes. Experimental results show that the photo catalytic activity of the membranes is high and stable in the process of treating Rhodamine B; the application of an electric field accelerates the speed of photo catalysis, and the efficiency of photo catalysis is increased 2.5 times when the applied voltage is 0.8 V; and the degradation of Rhodamine B follows the dynamics of first order reaction. It is concluded from the discussion of experimental results that the preparation process of TiO 2 activated carbon complex membranes is a simple low cost process suitable for large scale application.

Impacts of CO_2 enrichment on growth and photosynthesis in freshwater and marine diatoms

The physiological responses of Nitzschia palea Kvtzing, a freshwater diatom, to elevated CO2 were investigated and compared with those of a marine diatom, Chaetoceros muelleri Lemmermann previously reported. Elevated CO2 concentration to 700 μl/L increased the dissolved inorganic carbon （D!C） and lowered the pH in the cultures of N. palea, thus enhancing the growth by 4%-20% during the whole growth period. High CO2-grown N. palea cells showed lower levels of dark respiration rates and higher Ik values. Light-saturated photosynthetic rates and photosynthetic efficiencies decreased in N. palea with the doubling CO2 concentration in airflow to the bottom of cultures, although the doubling CO2 concentration in airflow to the surface cultures had few effects on these two photosynthetic parameters. N. palea cells were found to be capable of using HCO5 in addition to gaseous CO2, and the CO2 enrichment decreased their affinity for HCO5 and CO2. Although doubled CO2 level would enhance the biomass of N. patea and C. muelleri to different extents, compared with the marine diatom, it had a significant effect on the specific growth rates of N. palea. In addition, the responses of photosynthetic parameters of IV. palea to doubled CO2 concentration were almost opposite to those of C. muelleri.

LSDA+U study on the electronic and anti-ferromagnetic properties of Ni-doped CuO and Cu-doped NiO

Doping is an effective way to improve the activity of photocatalysts.The effect of doping on the magnetic properties of some photocatalysts that are easily recycled was studied using the local spin density approximation(LSDA)+U method on typical divalent metal oxide semiconductors CuO,NiO,Ni‐doped CuO,and Cu‐doped NiO.It is found that the influence of Ni doping on the spatial structure of CuO and that of Cu doping on the spatial structure of NiO are negligible because of the similar radii of Ni2+and Cu2+.The valence band and conduction band for Ni‐doped CuO are clearly spin‐split,corresponding to a net effective magnetic moment ofμeff=1.66μB.This may improve the photocatalytic efficiency and raise the recycle rate of photocatalysts.In the Cu‐doped NiO system,the presence of Cu3d states near to the Fermi level increases the width of the valence band and narrows the band gap with respect to that in pure NiO.Beyond the Cu3d states,within the band gap,appear two energy levels around the Fermi level,which may effectively separate the electron‐hole pair and also lead to enhanced absorption of visible light and infrared light.It can be concluded that the observed changes in the band structure may be helpful for improving the activity of photocatalysts and the doped systems have net magnetic moments,meaning that they are easily recycled and can be reused.

THE BIOGEOCHEMISTRY OF PHOTOSYNTHETIC PIGMENTS IN THE JIULONG RIVER ESTUARY AND WESTERN XIAMEN BAY

High performance liquid chromatography (HPLC) analysis of photosynthetic pigments in samples from Western Xiamen Bay and the Jiulong River Estuary showed that their major carotenoids were fucoxanthin, peridinin, zeaxanthin, violaxanthin, and diadinoxanthin. Diatoms dominated in the spring bloom, dinoflagellates in summer. Violaxanthin and chlorophyll b indicated the appearance of chrysophytes and green algae, most of which were freshwater species. The high phytoplankton biomass region was located at the inner part of the bay. Diatoms and dinoflagellates dominated phytoplankton communities, contributing to over 50% of total biomass. All the main diagnostic carotenoids were significantly (P<0.01) correlated negatively to dissolved inorganic phosphorus, suggesting that they were limited by phosphorus. The high negative linear relationship (P<0.0001) between dissolved inorganic phosphorus and peridinin (dinoflagellates indicator) implied the potential of dissolved inorganic phosphorus for triggering red tide events in this region.