Developmental characteristics and response to iron toxicity of root border cells in rice seedlings

To investigate the Fe^2＋ effects on root tips in rice plant, experiments were carried out using border cells in vitro. The border cells were pre-planted in aeroponic culture and detached from root tips. Most border cells have a long elliptical shape. The number and the viability of border cells in situ reached the maxima of 1600 and 97.5%, respectively, at 20---25 mm root length. This mortality was more pronounced at the first 1-12 h exposure to 250 mg/L Fe^2＋ than at the last 12-36 h. After 36 h, the cell viability exposed to 250 mg/L Fe^2＋ decreased to nought, whereas it was 46.5% at 0 mg/L Fe^2＋. Increased Fe^2＋ dosage stimulated the death of detached border cells from rice cultivars. After 4 h Fe^2＋ treatment, the cell viabilities were _〉80% at 0 and 50 mg/L Fe^2＋ treatment and were 〈62% at 150, 250 and 350 mg/L Fe^2＋ treatment; The viability of border cells decreased by 10% when the Fe^2＋ concentration increased by 100 mg/L. After 24 h Fe^2＋ treatment, the viabilities of border cells at all the Fe^2＋ levels were 〈65%; The viability of border cells decreased by 20% when the Fee＋ concentration increased by 100 mg/L. The decreased viabilities of border cells indicated that Fe^2＋ dosage and treatment time would cause deadly effect on the border cells. The increased cell death could protect the root tips from toxic harm. Therefore, it may protect root from the damage caused by harmful iron toxicity.     

Mechanisms and assessment of water eutrophication

Water eutrophication has become a worldwide environmental problem in recent years, and understanding the mechanisms of water eutrophication will help for prevention and remediation of water eutrophication. In this paper, recent advances in current status and major mechanisms of water eutrophication, assessment and evaluation criteria, and the influencing factors were reviewed. Water eutrophication in lakes, reservoirs, estuaries and rivers is widespread all over the world and the severity is increasing, especially in the developing countries like China. The assessment of water eutrophication has been advanced from simple individual parameters like total phosphorus, total nitrogen, etc., to comprehensive indexes like total nutrient status index. The major influencing factors on water eutrophication include nutrient enrichment, hydrodynamics, environmental factors such as temperature, salinity, carbon dioxide, element balance, etc., and microbial and biodiversity. The occurrence of water eutrophication is actually a complex function of all the possible influencing factors. The mechanisms of algal blooming are not fully understood and need to be further investigated.     

Accumulation and distribution of arsenic and cadmium by tea plants

It is important to research the rules about accumulation and distribution of arsenic and cadmium by tea plants, which will give us some scientific ideas about how to control the contents of arsenic and cadmium in tea. In this study, by field investigation and pot trial, we found that mobility of arsenic and cadmium in tea plants was low. Most arsenic and cadmium absorbed were fixed in feeding roots and only small amount was transported to the above-ground parts. Distribution of arsenic and cadmium, based on their concentrations of unit dry matter, in tea plants grown on un-contaminated soil was in the order： feeding roots〉stems=main roots〉old leaves〉young leaves. When tea plants were grown on polluted soils simulated by adding salts of these two metals, feeding roots possibly acted as a buffer and defense, and arsenic and cadmium were transported less to the aboveground parts. The concentration of cadmium in soil significantly and negatively correlated with chlorophyll content, photosynthetic rate, transpiration rate and biomass production of tea plants.     

Problems of drinking water treatment along Ismailia Canal Province, Egypt

The present drinking water purification system in Egypt uses surface water as a raw water supply without a preliminary filtration process. On the other hand, chlorine gas is added as a disinfectant agent in two steps, pre- and post-chlorination. Due to these reasons most of water treatment plants suffer low filtering effectiveness and produce the trihalomethane （THM） species as a chlorination by-product. The Ismailia Canal represents the most distal downstream of the main Nile River. Thus its water contains all the proceeded pollutants discharged into the Nile. In addition, the downstream reaches of the canal act as an agricultural drain during the closing period of the High Dam gates in January and February every year. Moreover, the wide in- dustrial zone along the upstream course of the canal enriches the canal water with high concentrations of heavy metals. The obtained results indicate that the canal gains up to 24.06 × 10^6 m^3 of water from the surrounding shallow aquifer during the closing period of the High Dam gates, while during the rest of the year, the canal acts as an influent stream losing about 99.6× 10^6 m^3 of its water budget. The reduction of total organic carbon （TOC） and suspended particulate matters （SPMs） should be one of the central goals of any treatment plan to avoid the disinfectants by-products. The combination of sedimentation basins, gravel pre-filtration and slow sand filtration, and underground passage with microbiological oxidation-reduction and adsorption criteria showed good removal of parasites and bacteria and complete elimination of TOC, SPM and heavy metals. Moreover, it reduces the use of disinfectants chemicals and lowers the treatment costs. However, this purification system under the arid climate prevailing in Egypt should be tested and modified prior to application.     

Phytoremediation of heavy metal polluted soils and water: Progresses and perspectives

Environmental pollution affects the quality ofpedosphere, hydrosphere, atmosphere, lithosphere and biosphere. Great efforts have been made in the last two decades to reduce pollution sources and remedy the polluted soil and water resources. Phytoremediation, being more cost-effective and fewer side effects than physical and chemical approaches, has gained increasing popularity in both academic and practical circles. More than 400 plant species have been identified to have potential for soil and water remediation. Among them, Thlaspi, Brassica, Sedum alfredii H., and Arabidopsis species have been mostly studied. It is also expected that recent advances in biotechnology will play a promising role in the development of new hyperaccumulators by transferring metal hyperaccumulating genes from low biomass wild species to the higher biomass producing cultivated species in the times to come. This paper attempted to provide a brief review on recent progresses in research and practical applications of phytoremediation for soil and water resources.     

Microbial activity and community diversity in a variable charge soil as affected by cadmium exposure levels and time

Effects of cadmium （Cd） on microbial biomass, variable charge soil （Typic Aquult） using an incubation study activity and community diversity were assessed in a representative Cadmium was added as CdCNO3）2 to reach a concentration range of 0-16 mg Cd/kg soil. Soil extractable Cd generally increased with Cd loading rate, but decreased with incubation time. Soil microbial biomass was enhanced at low Cd levels （0.5-1 mg/kg）, but was inhibited consistently with increasing Cd rate. The ratio of microbial biomass C/N varied with Cd treatment levels, decreasing at low Cd rate （〈0.7 mg/kg available Cd）, but increasing progressively with Cd loading. Soil respiration was restrained at low Cd loading （〈1 mg/kg）, and enhanced at higher Cd levels. Soil microbial metabolic quotient （MMQ） was generally greater at high Cd loading （1-16 mg/kg）. However, the MMQ is also affected by other factors. Cd contamination reduces species diversity of soil microbial communities and their ability to metabolize different C substrates. Soils with higher levels of Cd contamination showed decreases in indicator phospholipids fatty acids （PLFAs） for Gram-negative bacteria and actinomycetes, while the indicator PLFAs for Gram-positive bacteria and fungi increased with increasing levels of Cd contamination.     

Spatial distribution of Cd and Cu in soils in Shenyang Zhangshi Irrigation Area （SZIA）, China

Heavy metal contamination of soils, derived from sewage irrigation, mining and inappropriate utilization of various agrochemicals and pesticides, and so on, has been of wide concern in the last several decades. The Shenyang Zhangshi Irrigation Area （SZIA） in China is a representative area of heavy metal contamination of soils resulting from sewage irrigation for about 30 years. This study investigated the spatial distribution and temporal variation of soil cadmium （Cd） and copper （Cu） contamination in the SZIA. The soil samples were collected from the SZIA in 1990 and 2004; Cd and Cu in soils was analyzed and then the spatial distribution and temporal variation of Cd and Cu in soils were modeled using Kriging methods. The results show that long-term sewage irrigation had caused serious Cd and Cu contamination in soils. The mean and the maximum of soil Cd are markedly higher than the levels in second grade standard soil （LSGSS） in China, and the maximum of soil Cu is close to the LSGSS in China in 2004 and is more than the LSGSS in China in 1990. The contamination magnitude of soil Cd and the soil extent of Cd con- tamination had evidently increased since sewage irrigation ceased in 1992. The contamination magnitude of soil Cu and the soil extent of Cu contamination had evidently increased in topsoil, but obviously decresed in subsoil. The soil contamination of Cd and Cu was mainly related to Cd and Cu reactivation of contaminated sediments in Shenyang Xi River and the import of Cd and Cu during irrigation. The eluviation of Cd and Cu in contaminated topsoil with rainfall and irrigation water was another factor of temporal-spatial variability of Cd and Cu contamination in soils.     

Differential generation of hydrogen peroxide upon exposure to zinc and cadmium in the hyperaccumulating plant specie （Sedum alfredii Hance）

Sedum alfredii Hance has been identified as zinc （Zn） and cadmium （Cd） co-hyperaccumulator. In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H. were examined. The results show that Zn and Cd contents in the shoots of Sedum alfredii H. treated with 1000 μmol/L Zn^2＋ and/or 200 μmol/L Cd^2＋ increased linearly within 15 d. Contents of total S, glutathione （GSH） and H2O2 in shoots also increased within 15 d, and then decreased. Total S and GSH contents in shoots were higher under Cd^2＋ treatment than under Zn^2＋ treatment. However, reverse trends of H2O2 content in shoots were obtained, in which much higher H2O2 content was observed in Zn^2＋ -treated shoots than in Cd^2＋-treated shoots. Similarly, the microscopic imaging of H2O2 accumulation in leaves using H2O2 probe technique showed that much higher H2O2 accumulation was observed in the Zn^2＋-treated leaf than in the Cd^2＋ -treated one. These results suggest that there are different responses in the generation of H2O2 upon exposure to Zn^2＋ and Cd^2＋ for the hyperaccumulator Sedum alfredii H. And this is the first report that the generation of H2O2 may play an important role in Zn hyperaccumulation in the leaves. Our results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H2O2.     

植酸改性对AZ31镁合金表面细胞黏附性能的影响

用浸没法在AZ31镁合金表面制备植酸涂层,用携带能谱仪的扫描电子显微镜研究了表面涂层的化学组成和形貌,并用直接法和间接法分别在植酸改性前后的镁合金表面培养细胞,检测细胞存活率,考查人骨肉瘤细胞在植酸改性前后镁合金表面的黏附能力。结果表明：在镁合金表面形成均匀的植酸涂层,植酸改性前后镁合金对细胞存活率影响相近,但细胞在植酸改性前后镁合金表面的黏附能力存在显著差异,植酸改性可有效改善AZ31镁合金的细胞黏附性能。     

Redox condition during Ediacaran–Cambrian transition in the Lower Yangtze deep water basin,South China: constraints from iron speciation and δ~(13) Corg in the Diben section,Zhejiang

Cherts of the Piyuancun Formation and black mudstones of the Hetang Formation in Diben Town, Kaihua County, Zhejiang were deposited in a deep water basin of the Lower Yangtze area during the Ediacaran–Cambrian transition(E–C transition), offering an opportunity to reconstruct the ancient redox condition of the deep water basin. Total 53 samples were collected and analyzed for iron speciation, including pyrite iron(FePy), carbonate associated iron(FeCarb), iron oxide and hydroxide(FeOx),magnetite iron(FeMag) and total iron(FeT) as well as d13 Corgto gain a deeper understanding of specific redox condition during the period. The results show that(1) most samples have pyrite concentration \1 %, with the FePy/FeHR ratio ranging from \0.01 to 0.81(mostly \0.5), and the FeHR/FeT ratio between 0.39 and 0.93(mostly [0.5).(2) The E–C boundary in the Diben section occurred at the maximum negative excursion of organic carbon isotope within the Piyuancun Formation, which can be correlated with other sections by using d13 Corg. We thus concluded that the relatively high content of highly reactive iron and low content of pyrite iron in the Diben section indicate a minor occurrence of H2 S and a predominance of anoxic and ferruginous environment, which is similar to other reported sections such as the Longbizui and Yanwutan sections, western Hunan. In addition, oxygen concentration in sea water showed an increasing trend in the interval corresponding to the bottom and upper layer of the Hetang Formation as indicated by the FeHR/FeT ratio, which decreased from 0.7 to 0.38, however, it was not great enough to oxidize the whole deep water. Therefore, during the E–C transition deep water basin in South China was most likely an anoxic and ferruginous enrironment, which prevented metazoon from the evolution in the deep water basin. Our work offers an important reference to better understanding of the spatiotemporal occurrence and dynamic processes of the ‘‘Cambrian Explosion'.     

发生在强碱溶液之间的反应H~＋＋OH~－＝H_2O

在传统观念中,只有酸与减溶液才能发生Ｈ＋＋ＯＨ－＝Ｈ２Ｏ的反应．笔者认为：碱与碱,酸与酸,以及任何两种不同ＰＨ值的溶液之间,均可发生Ｈ＋＋ＯＨ－＝Ｈ２Ｏ的反应。     

由菲汀制取植酸钠及植酸的生产工艺研究

采用化学沉淀法由菲汀制取植酸和植酸钠.菲汀经酸浸、沉淀、加碱使沉淀转化可制得植酸钠溶液.植酸钠溶液经减压浓缩、乙醇结晶可制得针状的植酸钠晶体,或经离子交换树脂酸化、浓缩可得浓度为70%的植酸.     

2，2-二硒化双苯甲酸和2，2-二硫化双苯甲酸的合成与晶体结构

以邻氨基苯甲酸、多硒化钠和多硫化钠等为原料,通过重氮化反应分别合成了2,2-二硒化双苯甲酸（1）和2,2-二硫化双苯甲酸（2）,在DM F溶液中获得适于单晶X射线衍射的晶体,结构通过X射线衍射分析确定．化合物1属单斜晶系,空间群为 C1/c ．a＝0．8222（4） nm ,b＝1．3229（6） nm ,c＝2．1841（12） nm ,β＝96．475（3）°,Mr ＝546．33,V＝2．3607（2）nm3,Z＝4,Dc ＝1．537 g/cm3,μ＝3．168 mm-1,F（000）＝1096．最终偏离因子 R1＝0．0365,w R2＝0．0851,S＝1．032．化合物2属三斜晶系,空间群为 p1．a＝0．7563（14） nm ,b＝0．7729（14） nm ,c＝2．0061（4） nm ,α＝83．408（5）°,β＝84．961（5）°,γ＝83．056（5）°,Mr ＝452．53,V＝1．1531（4） nm3,Z＝2,Dc ＝1．303 g/cm3,μ＝0．268 mm-1,F（000）＝476．最终偏离因子 R1＝0．0543,wR2＝0．1361,S＝1．074．化合物1和2中均存在分子内和分子间氢键以及C- H…π为非常规的氢键．     

Preparation and Structural Analysis of Lanthanide Complexes with α-Hydroxyl-phenyl-acetic Acid and 1, 10-Phenanthroline as Ligands

A series of ternary lanthanide complexes Ln （C6H5CHOHCOO）3（phen） （H2O） （Ln= La, Ce, Pr, Nd, Sm, Eu） were synthesized with α-hydroxyl-phenyl-acetic acid and 1, 10-phenanthroline （phen） as ligands. The sturcture and property of complexes were characterized by elemental analysis, IR, 1^H-NMR, UV and TGA, and the coordinate mede of both ligands was discussed. It was shown that the co-ordinate mode of 1, 10-phenanthroline was chelated, while α-hydraxyl-phenyl-acetate ion was monedentate or bridging. The mechanism of thermal determinde by thermogravimetry was indicated that the degree of co-ordinate ability of ligand was： α-hydroxyl-phenyl-acetate ion 〉 1, 10- phenanthroline（phen）.     

Dehydration melting of UHP eclogite and paragneiss in the Dabie orogen: Evidence from laboratory experiment to natural observation

Dehydration melting of subducted continental crust is significant during exhumation, and its study from both experimental and petrological observations is of great importance to our understanding of continental geodynamics. Dehydration melting experi- ments were carried out on ultrahigh-pressure （UHP） eclogite from Bixiling in the Dabie orogen using a piston cylinder at 1.5-3.0 GPa and 800-950℃ to investigate partial melting of eclogite induced by phengite breakdown. The phengite-bearing eclogite started to melt at T≤800-850℃ and P=1.5-2.0 GPa and produced about 3% granitic melt. The products of dehydration melting vary with temperature and pressure. Such results provide valuable constraints on the micro-texture related to partial melting of UHP rocks in the Dabie-Sulu orogenic belt. Three types of polyphase inclusions were identified in garnet from the Shuanghe UHP eclogite. K-feldspar and quartz inclusions are interpreted to represent the products of segregation and crystallization of minor amounts of melt that formed during dehydration melting of phengite by the inferred reaction Phengite＋Omphacite＋Quartz Amphibole_＋Garnet＋Melt （K-feldspar＋Quartz＋Plagioclase）. Polyphase inclusions of phengite and K-feldspar＋Quartz inclusions were also found in zoisite/clinozoisite and garnet from the Shuanghe garnet-bearing paragneiss. These polyphase inclusions pro- vide evidence for a continuous process from sub-solidus dehydration to partial melting within the UHP gneissic rocks. The com- positional variation of garnets demonstrates that breakdown of epidote-group minerals may have played a crucial role during de- hydration melting reaction of phengite. The Ti-in-zircon thermometry and Si content of phengite in zircon suggest that partial melting would occur at 783-839℃ and 2.0-2.5 GPa. Therefore, both experimental results and petrological observations indicate that dehydration melting and fluid activity within the Dabie UHP rocks at micro-scale are controlled by the breakdown of phengite.     

Weak interaction between CH3SO and HOCl: Hydrogen bond, chlorine bond and oxygen bond

B3lyp/6-311＋＋g＊＊ and mp2/6-311＋＋g＊＊ calculations were used to analyze the interaction between CH3SO and HOCl. Nine （complex A： S1A-S9A） and five （complex B： S4B-S7B and S10B） minima were localized on the potential energy surface of CH3SO…HOCl complexes at b3lyp/6-311＋＋g＊＊ and mp2/ 6-311＋＋g＊＊ computational levels, respectively. The AIM and NBO theories were also applied to explain the nature of the complexes. Bonding energy of complexes A and B corrected with BSSE falls in the ranges of -0.4―-41.4 kJ·mol-1 and -6.9―-35.8 kJ·mol-1 at mp2/6-311＋＋g＊＊ level, respectively. The re- sults show that a novel oxygen bond complex （S6） exists in the system, besides hydrogen bond and chlorine bond. Especially, S6B-F, S6B-Br and S7B are blue shifted complexes compared with red shifted S6A, because the electron transfer occurs between LP1（S8） and σ＊（O5-Cl7）, resulting in the increase of O5-Cl7 and the decrease of vibrational frequency. The complex of S10B has characteristics of both red shift and blue shift.     

Effects of different types of palatal lateral excisions on growth and development of maxilla and dental arch

Objective： This study aimed to explore the effects of different types of palatal lateral excisions on the growth and development of the maxilla and dental arch, and to investigate the underlying mechanisms. Methods： A total of 112 3-week-old Sprague-Dawley （SD） male rats were randomly divided into a control and 3 experimental groups： the mucoperiosteal denudation group, the mucosal flap excision group, and the periosteum excision group. In the experimental groups, bilateral mucoperiosteal, mucosal flap and periosteum were excised respectively in the lateral one half of the palate. Four rats in each group were randomly chosen for sacrifice every two weeks. The maxilla was dissected following the excision. The widths of the maxilla and dental arch were measured and the histological phenomena were investigated at different phases. At the same time, 12 animals in each group were sequentially injected with calcein every two weeks. Three animals in each group, whose fluorescent labeling was used, were sacrificed for investigating bone formation at Week 8 following injection. Results： （1） Each experimental group presented the constriction of the maxilla and dental arch. The upper first molars in the experimental groups inclined medially. The mucoperiosteal denudation group showed the largest degree of effect followed by the periosteum excision group. The indices of the mucosal flap excision group, which retained the structures of the periosteum layer, had the most approximate values to the control group; （2） Different histological changes among the experimental groups were detected. The fibers penetrated into the palatal bone as Sharpey＇s fibers in the mucoperiosteal denudation group. The pattern of bone deposition was the bundle type. Sharpey＇s fibers were not found in the mucosal flap and periosteum excision groups and the depositions of palatal bone were the lamellar type as those in the control group; （3） The rates of bone deposition in the experimental groups decreased compared with the