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.     

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.     

Phytate: impact on environment and human nutrition. A challenge for molecular breeding

Phytic acid （PA） is the primary storage compound of phosphorus in seeds accounting for up to 80% of the total seed phosphorus and contributing as much as 1.5% to the seed dry weight. The negatively charged phosphate in PA strongly binds to metallic cations of Ca, Fe, K, Mg, Mn and Zn making them insoluble and thus unavailable as nutritional factors. Phytate mainly accumulates in protein storage vacuoles as globoids, predominantly located in the aleurone layer （wheat, barley and rice） or in the embryo （maize）. During germination, phytate is hydrolysed by endogenous phytase（s） and other phosphatases to release phosphate, inositol and micronutrients to support the emerging seedling. PA and its derivatives are also implicated in RNA export, DNA repair, signalling, endocytosis and cell vesicular trafficking. Our recent studies on purification of phytate globoids, their mineral composition and dephytinization by wheat phytase will be discussed. Biochemical data for purified and characterized phytases isolated from more than 23 plant species are presented, the dephosphorylation pathways of phytic acid by different classes of phytases are compared, and the application of phytase in food and feed is discussed.     

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.     

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.     

Natural water purification and water management by artificial groundwater recharge

Worldwide, several regions suffer from water scarcity and contamination. The infiltration and subsurface storage of rain and river water can reduce water stress. Artificial groundwater recharge, possibly combined with bank filtration, plant puri- fication and/or the use of subsurface dams and artificial aquifers, is especially advantageous in areas where layers of gravel and sand exist below the earth＇s surface. Artificial infiltration of surface water into the uppermost aquifer has qualitative and quantitative advantages. The contamination of infiltrated river water will be reduced by natural attenuation. Clay minerals, iron hydroxide and humic matter as well as microorganisms located in the subsurface have high decontamination capacities. By this, a final water treatment, if necessary, becomes much easier and cheaper. The quantitative effect concerns the seasonally changing river discharge that influences the possibility of water extraction for drinking water purposes. Such changes can be equalised by seasonally adapted infiltration/extraction of water in/out of the aquifer according to the river discharge and the water need. This method enables a continuous water supply over the whole year. Generally, artificially recharged groundwater is better protected against pollution than surface water, and the delimitation of water protection zones makes it even more save.     

Groundwater protection： What can we learn from Germany？

For drinking water security the German waterworks proceed on a comprehensive concept, i.e., the protection of all the regions from the recharge area to the client. It includes the protection of the recharge area by a precautionary management, a safe water treatment, a strict maintenance of the water distribution network, continuous control and an intensive training of staff. Groundwater protection zones together with effective regulations and control play a very important role. Three protection zones with different restrictions in land-use are distinguished. Water in reservoirs and lakes is also protected by Surface Water Protection Zones. Within the surrounding area the land-use is controlled, too. Special treatment is necessary if acidification happens caused by acid rain, or eutrophication caused by the inflow of sewage. Very important is the collaboration between waterworks and the farmers cultivating land in the recharge area in order to execute water-protecting ecological farming with the aim to reduce the application of fertilizers and plant protection agents. Probable financial losses have to be compensated by the waterworks.     

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.     

微生物絮凝剂MBFA9去除水中Pb~(2+)的机理

从土壤中筛选得到一株类芽孢杆菌A9,所产微生物絮凝剂MBFA9对水中Pb2+具有较高的去除作用,并进一步考察了MBFA9对Pb~(2+)的吸附动力学和热力学过程.结果表明:当水中初始Pb2+质量浓度为56.20 mg/L,MBFA9吸附25 min后的去除率最高可达92.73%;MBFA9捕集Pb2+的理论最大值为196.08 mg/g,吸附速率常数k2为0.019 g/(mg·min),动力学特征符合准二级动力学模型,其等温吸附模型与Langmuir方程拟合较好,相关系数R2=0.96;结合红外光谱检测、场发射扫描电镜和能谱分析,探讨了M BFA9去除Pb2+的机理为其表面的官能团如羟基、酰胺基、羧基等在捕集Pb2+过程中与之发生配合作用,对Pb2+的去除贡献了重要作用.     

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     

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.     

Optimization of acidic extraction of astaxanthin from Phaffia rhodozyma

Optimization of a process for extracting astaxanthin from Phaffia rhodozyma by acidic method was investigated, regarding several extraction factors such as acids, organic solvents, temperature and time. Fractional factorial design, central composite design and response surface methodology were used to derive a statistically optimal model, which corresponded to the following optimal condition： concentration of lactic acid at 5.55 mol/L, ratio of ethanol to yeast dry weight at 20.25 ml/g, temperature for cell-disruption at 30 ℃, and extraction time for 3 min. Under this condition, astaxanthin and the total carotenoids could be extracted in amounts of 1294.7 μg/g and 1516.0 μg/g, respectively. This acidic method has advantages such as high extraction efficiency, low chemical toxicity and no special requirement of instruments. Therefore, it might be a more feasible and practical method for industrial practice.     

A novel portable transmitter with 8dBm output power for wireless communication equipments

In this paper,a portable 2.42 GHz transmitter for wireless communication systems,with 8dBm output power and small size is proposed.Several novel features exist in this transmitter.First,power consumption and output are balanced by introducing a differential oscillator with input signal controlled biasing,which acts as both a carrier generator and an OOK modulator.Then,power consumption of the transmitter is reduced by the OOK modulated signal via switching the oscillator and the power amplifier at the same time.Furthermore,the area size is also reduced by a class-AB power amplifier,which uses the PCB antenna as the resonance inductance.With these features,the total chip area is reduced to 670μm×740μm(In a 0.18μm CMOS process).     

A polynomial smooth epsilon-support vector regression based on cubic spline interpolation

Regression analysis is often formulated as an optimization problem with squared loss functions.Facing the challenge of the selection of the proper function class with polynomial smooth techniques applied to support vector regression models,this study takes cubic spline interpolation to generate a new polynomial smooth function |x|_ε~2 in ε-insensitive support vector regression.Theoretical analysis shows that S_ε~2-function is better than p_ε~2-function in properties,and the approximation accuracy of the proposed smoothing function is two order higher than that of classical p_ε~2-function.The experimental data shows the efficiency of the new approach.     

Drainage after total thyroidectomy or lobectomy for benign thyroidal disorders

Objective： This prospective randomized clinical trial was conducted to evaluate the necessity of drainage after total thyroidectomy or lobectomy for benign thyroidal disorders. Methods： A total of 116 patients who underwent total thyroidectomy or lobectomy for benign thyroidal disorders were randomly allocated to be drained or not. Operative and postoperative outcomes including operating time, postoperative pain assessed by visual analogue scale （VAS）, total amount of intramuscular analgesic administration, hospital stay, complications, necessity for re-operation and satisfaction of patients were all assessed. Results： The mean operating time was similar between two groups （the drained and non-drained groups）. The mean VAS score was found to be significantly low in the non-drained group patients in postoperative day （POD） 0 and POD 1. The mean amount of intramuscular analgesic requirement was significantly less in the non-drained group. One case of hematoma, two cases ofseroma and three cases of transient hypoparathyroidism occurred in the non-drained group, whereas one case of hematoma, two cases of seroma, two cases of wound infections and two cases of transient hypoparathyroidism occurred in the drained group. No patient needed re-operation for any complication. The mean hospital stay was significantly shorter and the satisfaction of patients was superior in the non-drained group. Conclusion： These findings suggest that postoperative complications cannot be prevented by using drains after total thyroidectomy or lobectomy for benign thyroid disorders. Furthermore, the use of drains may increase postoperative pain and the analgesic requirement, and prolong the hospital stay. In the light of these findings, the routine use of drains might not be necessary after thyroid surgery for benign disorders.     

Real-time haptic model for soft tissue deformation in surgery simulation

The modelling and simulation of deformable objects is a challenging topic in the field of haptic rendering between human and virtual environment. In this paper, a novel and efficient layered rhombus-chain-connected haptic deformation model based on physics is proposed for an excellent haptic rendering. During the modelling, the accumulation of relative displacements in every chain structure unit in each layer is equal to the deformation on the virtual object surface, and the resultant force of corresponding springs is equivalent to the external force. The layered rhombus-chain-con- nected model is convenient and fast to calculate, and can satisfy real-time requirement due to its simple nature. Simulation experiments in virtual human liver based on the proposed model are con- ducted, and the results demonstrate that our model provides stable and realistic haptic feeling in real time. Meanwhile, the display result is vivid.