Assessment of water pollution control strategies: a case study for the Dianchi Lake

Lake eutrophication has increasingly become a major environmental issue in China. Although significant efforts have been made towards its resolution in the last decade, most of the implemented control strategies are fragmented, and the formation of policy lacks of sound scientific basis and long\|term objectives. Taking the well\|known Dianchi Lake as a case study, this paper presented a comprehensive assessment for the effectiveness of various eutrophication control strategies. It is expected that the concluding lessons would have a major implication to future eutrophication control.

Application of TLSER method in predicting the aqueous solubility and n-octanol/water partition coefficient of PCBs,PCDDs and PCDFs

The theoretical linear solvation energy relationship(TLSER) approach was adopted to predict the aqueous solubility and n -octanol/water partition coefficient of three groups of environmentally important chemicals-polychlorinated biphenyls(PCBs), polychlorinated dibenzodioxins and dibenzofurans(PCDDs and PCDFs). For each compound, five quantum parameters were calculated using AM1 semiempirical molecular orbital methods and used as structure descriptors: average molecular polarizability(α), energy of the lowest unoccupied molecular orbit( E _ LUMO ), energy of the highest occupied molecular orbit( E _ HOMO ), the most positive charge on a hydrogen atom( q _+), and the most negative atomic partial charge( q _-) in the solute molecule. Then standard independent variables in TLSER equation was extracted and two series of quantitative equations between these quantum parameters and aqueous solubility and n -octanol/water partition coefficient were obtained by stepwise multiple linear regression(MLR) method. The developed equations have both quite high accuracy and explicit meanings. And the cross-validation test illustrated the good predictive power and stability of the established models. The results showed that TLSER could be used as a promising approach in the estimation of partition and solubility properties of macromolecular chemicals, such as persistent organic pollutants.

Effect of nitrogen concentration in culture mediums on growth and enzyme production of Phanerochaete chrysosporium

Effect of different nitrogen concentration in the mediums on growth and enzyme production of Phanerochaete chrysosporium was studied when glucose concentration was 10 g/L. The results showed that the medium contained 0.8 g/L ammonium tartrate is the best. It not only supply abundant nutrients for the growth of Phanerochaete chrysosporium, which make mycelia the best grow compared with the other medium, but also produce higher manganese-dependent peroxidase(Mnp) and laccase(Lac) activity. In addition, it is observed that the variation of mycelia surface is related to ligninolytic enzyme secreted by Phanerochaete chrysosporium. When the surface of mycelium pellets appeared burs, it predicts secondary metabolism begin. This experimentation demonstrated that when the ratio of carbon and nitrogen in nitrogen limited medium is equal to 100∶8, growth and enzyme production of Phanerochaete chrysosporium is the best, it could achieve the maximum Mnp and Lac activity.

Composting MSW and sewage sludge with effective complex microorganisms

The effects of complex microorganisms in composting process of the municipal solid waste (MSW) and sludge were examined through inspecting biomass, temperature, oxygen consumption, organic mater, and C/N (the ratio of carbon and nitrogen). The experimental results shows: complex microorganisms are effective to compose organic matter and speedup composting change into humus.

Identification of two distinct transactivation domains in the pluripotency sustaining factor nanog

Nanog is a newly identified homeodomain gene that functions to sustain the pluripotency of embryonic stem cells.However,the molecular mechanism through which nanog regulates stem cell pluripotency remains unknown.Mouse nanog encodes a polypeptide of 305 residues with a divergent homeodomain similar to those in the NK-2 family.The rest ofnanog contains no apparent homology to any known proteins characterized so far.It is hypothesized that nanog encodes a transcription factor that regulates stem cell pluripotency by switching on or off target genes.To test this hypothesis,we constructed fusion proteins between nanog and DNA binding domains of the yeast transcription factor Gal4 and tested the transactivation potentials of these constructs.Our data demonstrate that both regions N- and C- terminal to the homeodomain have transcription activities.Despite the fact that it contains no apparent transactivation motifs,the C-terminal domain is about 7 times as active as the N-terminal one.This unique arrangement of dual transactivators may confer nanog the flexibility and specificity to regulate downstream genes critical for both pluripotency and differentiation of stem cells.

Anti-Helicobacterpyloriimmunoglobulin G(IgG)and IgA antibody responses and the value of clinical presentations in diagnosis of H.pyloriinfection in patients with precancerous lesions

AIM: To determine the prevalence of Helicobacter pylori (H. pylon) infection, the serum anti-H. pylori immunoglobulin G (IgG) and IgA antibody responses, and the value of clinical presentations in diagnosis of H. pylori infection in patients with gastric atrophy, intestinal metaplasia and dysplasia.METHODS: H. pylori infection was detected by histology in 209 patients with mild chronic atrophic gastritis (CAG, n=76),severe CAG (n=22), mild intestinal metaplasia (IM, n=22),severe IM (n=58), or dysplasia (DYS, n=31). Serum antiH. pylori IgG and IgA were double sampled and evaluated by enzyme-linked immunoadsordent assays. 35 clinical presentations were observed and their relationship with H.pylori infection was analyzed by the k-means cluster method.RESULTS: Both IgG and IgA levels in H. pylori positive patients were significantly higher than those negative for H.pylori(P＜0.001-0.01). The prevalence of H. pylori was highest in severe IM (84.5%), and lowest in mild CAG (51.3%)(P＜0.01). They were similar in severe CAG (68.2%), mild IN (72.7%), and DYS (67.7%). In H.pylori positive patients,the IgG levels in severe CAG were significantly higher than those in mild CAG (P＜0.01). In H.pylori negative patients,both IgG and IgA levels increased remarkably in severe IM,compared to those in mild IM (P＜0.01-0.05).H. pylori infection exhibited no association with patient′s gender (62.1% in males; 71.7 % in females) and age (r=0.0814, P=0.241).The diagnostic accuracy based on 35 clinical presentations was 65.7 %. It could be improved by 5.7% when only the assemblage of digestive symptoms were engaged, or by 8.6 % when the pathogenic factors, general status and grossoscopy were combined. The diagnostic accuracy could be decreased when only the general symptoms were engaged, or when the pathogenic factors were accompanied with some common digestive symptoms.CONCLUSION: H. pylori infection is a major risk factor for the process from atrophy, IM to DYS of gastric mucosa.Serum IgG and IgA are good indicators to evaluate this progress with a certain arrearage. Investigation on the effective assemblages of clinical presentations may provide a better understanding in the pathogenesis, diagnosis and treatment for H. pylori infection.

Deformation Characteristics of Loess Landslide along the Contact between Loess and Neocene Red Mudstone

The loess landslide along the contact between loess and Neogene red mudstone (NRM) is one of those that have occurred extensively and frequently in loess areas of China. To better understand the mechanism of this type of landslides, a distressed loess slope being subjected to deformation along the loess-NRM contact was comprehensively investigated through approaches of field monitoring and laboratory physical modeling. Field observation and physical modeling shows that the slope deformation will experience two distinct processes: 1) laterally retrogressive and vertically progressive propagation, which was initiated by falling of the slope head; and 2) retrogressively separate mass sliding along the weak basal zone of the loess-NRM contact with minor sliding along the paleosols within the loess. Shear failure of the loess-NRM contact may initiate in the middle section, followed by a progressive propagation towards the slope toe and inner slope. Analysis reveals that the deformation characteristics of the distressed slope are largely constrained by slope topography, the unique structure, physical and mechanical properties of loess and paleosols, and occurrence and nature of the loess-NRM contact. Rainfall has significantly influence on the deformation characteristics of the slope through its interaction with the loess and soil of the loess-NRM contact. Additionally, improper style and intensity of cutting on the slope greatly enhance and accelerate the deformation course of the slope.

Effects of low temperature on properties of structural steels

The experiments were carried out to measure the mechanical properties ofthree grades of structural steels (Q235A, 16Mn and Q390E steel) at low temperature. It was shownthat the strength of the steels increases while the plasticity and toughness decrease as temperaturedrops. In the transitional area the toughness drops rapidly with temperature. Among the threestructural steels, Q390E steel has the best toughness and the lowest sensitivity.

INVERSE KINEMATIC AND DYNAMIC ANALYSIS OF A 3-DOF PARALLEL MECHANISM

According to the structure character of the passive sub-chain of the 3TPS-TPparallel mechanism, the kinematic constraint equations of the movable platform are established,based on which the closed-form inverse kinematics formula of the parallel mechanism are presented.Through parting the spherical joints of the active sub-chains and using the force and momentequilibrium of both the active sub-chains and passive sub-chain, the constraint forces acting on theparted joints are determined. Subsequently, the analytic expressions of the actuator driving forcesare derived by means of the force equilibrium of the upper links of active sub-chains.

RESEARCH ON CONTROL OF FLYWHEEL SUSPENDED BY ACTIVE MAGNETIC BEARING SYSTEM WITH SIGNIFICANT GYROSCOPIC EFFECTS

Traditional PID controllers are no longer suitable formagnetic-bearing-supported high-speed flywheels with significant gyroscopic effects. Becausegyroscopic effects greatly influence the stability of the flywheel rotor, especially at highrotational speeds. Velocity cross feedback and displacement cross feedback are used to overcomeharmful effects of nutation and precession modes, and stabilize the rotor at high rotational speeds.Theoretical analysis is given to show their effects. A control platform based on RTLinut and a PCis built to control the active magnetic bearing (AMB) system, and relevant results are reported.Using velocity cross feedback and displacement cross feedback in a closed loop control system, theflywheel successfully runs at over 20000 r/min.

Stem cell pluripotency and transcription factor Oct4

Mammalian cell totipotency is a subject that has fascinated scientists for generations. A long lasting question whether some of the somatic cells retains totipotency was answered by the cloning of Dolly at the end of the 20th century. The dawn of the 21st has brought forward great expectations in harnessing the power of totipotentcy in medicine. Through stem cell biology, it is possible to generate any parts of the human body by stem cell engineering. Considerable resources will be devoted to harness the untapped potentials of stem cells in the foreseeable future which may transform medicine as we know today. At the molecular level, totipotency has been linked to a singular transcription factor and its expression appears to define whether a cell should be totipotent. Named Oct4, it can activate or repress the expression of various genes. Curiously, very little is known about Oct4 beyond its ability to regulate gene expression. The mechanism by which Oct4 specifies totipotency remains entirely unresolved. In this review, we summarize the structure and function of Oct4 and address issues related to Oct4 function in maintaining totipotency or pluripotency of embryonic stem cells.

Study on relative orbital configuration in satellite formation flying

In this paper, the relative orbital configurations of satellites in formation flying with non-perturbation and J2 perturbation are studied, and an orbital elements method is proposed to obtain the relative orbital configurations of satellites in formation. Firstly, under the condition of non-perturbation, we obtain many shapes of relative orbital configurations when the semi-major axes of satellites are equal. These shapes can be lines, ellipses or distorted closed curves. Secondly, on the basis of the analysis of J2 effect on relative orbital configurations, we find out that J2 effect can induce two kinds of changes of relative orbital configurations. They are distortion and drifting, respectively. In addition, when J2 perturbation is concerned, we also find that the semi-major axes of the leading and following satellites should not be the same exactly in order to decrease the J2 effect. The relationship of relative orbital elements and J2 effect is obtained through simulations. Finally, the minimum relation perturbation conditions are established in order to reduce the influence of the J2 effect. The results show that the minimum relation perturbation conditions can reduce the J2 effect significantly when the orbital element differences are small enough, and they can become rules for the design of satellite formation flying.

Risk forecasting and evaluating model of Environmental pollution accident

Environmental risk(ER) factors come from ER source and they are controlled by the primary control mechanism(PCM) of environmental risk, due to the self failures or the effects of external environment risk trigger mechanism, the PCM could not work regularly any more, then, the ER factors will release environmental space, and an ER field is formed up. The forming of ER field does not mean that any environmental pollution accident(EPA) will break out; only the ER receptors are exposed in the ER field and damaged seriously, the potential ER really turns into an actual EPA. Researching on the general laws of evolving from environmental risk to EPA, this paper bring forwards a relevant concept model of risk forecasting and evaluating of EPA. This model provides some scientific methods for risk evaluation, prevention and emergency response of EPA. This model not only enriches and develops the theory system of environment safety and emergency response, but also acts as an instruction for public safety, enterprise's safety management and emergency response of the accident.

Comparison of Di-n-methyl Phthalate Biodegradation by Free and Immobilized Microbial Cells

To compare the biodegradation of di-n-methyl pathalate by free and immobilized microbial cells. Methods The enrichment and isolation technique was used to isolate the microorganism. The PAV-entrapment method was utilized to immobilize the microorganisms. The scanning electron microscophy (SEM) was used to observe the growth and distribution of microbial cells immobilized inside the PVA bead gels. The GC/MS method was used to identify the main intermediates of DMP degradation. Results The microbial cells could grow quite well in PVA gel. The metabolic pathway did not change before and after immobilization of the microbial cells. The degradation rate of immobilized cells was higher than that of free cells. Conclusion The immobilized microbial cells possess advantages than free cells when applied to the biodegradation of toxic organic pollutants.

Tuning of Auto-disturbance-rejection Controller for a Class of Nonlinear Plants^1）

Design and adjusting rule of auto-disturbance rejection controller are proposed for aclass of first order nonlinear plants. Tracking differentiator and nonlinear combination are simpli-fied. According to the analysis of observing error of a secould order extended state observer, anempirical tuning rule is proposed based on theoretic deduction and simulations. Simulations on amultivariable plant with adjustable zeros demonstrate validity of the tuning rule.

Influence of nonionic surfactant on the solubilization and biodegradation of phenanthrene

Phenanthrene was solubilized in two different nonionic surfactants, Tween80 and Triton X-100. The bioavailability of phenanthrene to the bacteria isolated from the petroleum contaminated soils was studied based on the rotary flasks experiments. The results showed that the concentration of nonionic surfactants above the critical micelle concentration(CMC) can increase the solubility of phenanthrene in water and were innoxious to the phenanthrene-degrading bacteria; phenanthrene solubilized in the micelles of Tween80 was bioavailable and biodegradable. The research demonstrated the potential of surfactant-enhanced bioremediation of soils contaminated by hydrophobic organic compounds(HOCs).

Predicting physico-chemical properties of polychlorinated diphenyl ethers (PCDEs): potential persistent organic pollutants(POPs)

Polychlorinated diphenyl ethers(PCDEs) have received more and more concerns as a category of potential persistent organic pollutants(POPs). Modeling its environmental fate and exposure assessment require a number of fundamental physico-chemical properties. However, the experimental data are currently limited due to the difficulty in analysis caused by the complexity of PCDE congeners. As an alternative, the quantitative structure property relationship(QSPR) approach could be used. In this paper, twelve kinds of molecular connectivity indices(MCIs) of all 209 possible molecular structure patterns of PCDEs were calculated. Based on 106 PCDEs with three observed physico-chemical properties—vapour pressure(P 0 L), aqueous solubility(S w) and n-octanol/water(K ow ) and their MCIs data, a series of QSPR equations were established using multiple linear regression(MLR) method. As a result, three equations with best performance were selected mainly from the view of high regression coefficient(R) and low standard error(SE). All of them showed significant relationship and high accuracy. With these equations the properties of other 103 patterns of PCDEs without the reported observed values were predicted. Furthermore, three partition properties for PCDE congeners—Henry's Law constants(H), partition coefficients between gas/water(K gw ) and gas/n-octanol(K go ) were calculated according to the internal relationship among these six properties. These observed and predicted values, in contrast with the criteria listed in the Stockholm treaty about POPs which has been signed by more than ninety countries in May 2001, illustrated that most of PCDEs congeners are potential persistent organic pollutants. As all descriptors/predictors are derived just from the molecular structure itself and without the import of any empirical parameters, this method is impersonal and promising for the estimation of physico-chemical properties of PCDEs.

The AC losses measurement and analysis of superconducting NbTi CICC for HT-TU superconducting Tokamak

Superconducting TF and PF coils have been measured in SULTAN test facility. Segregated copper strands are included in four NbTi CICC and this is a technical innovation. Two AC losses measurement methods, calorimetric and electromagnetic methods, have been used in the experiments, and a broad frequency range (from 0.05 Hz to 6 Hz) is covered in sample test. The purpose of this experiment was to investigate AC losses of TF and PF CICC conductor including segregated copper and to check the design of PF and TF CICC coated with different resistive barriers (Pb-30Sn-2Sb and Ni plating on NbTi strands).

DIGITAL SPECKLE CORRELATION METHOD IMPROVED BY GENETIC ALGORITHM

The digital speckle correlation method is an important optical metrology for sur- face displacement and strain measurement.With this technique,the whole field deformation in- formation can be obtained by tracking the geometric points on the speckle images based on a correlation-matching search technique.However,general search techniques suffer from great com- putational complexity in the processing of speckle images with large deformation and the large random errors in the processing of images of bad quality.In this paper,an advanced approach based on genetic algorithms (GA) for correlation-matching search is developed.Benefiting from the abilities of global optimum and parallelism searching of GA,this new approach can complete the correlation-matching search with less computational consumption and at high accuracy.Two experimental results from the simulated speckle images have proved the efficiency of the new approach.

Dynamic analysis of fault rockburst based on gradient-dependent plasticity and energy criterion

Fault rockburst is treated as a strain localization problem under dynamicloading condition considering strain gradient and strain rate. As a kind of dynamic fracturephenomena, rockburst has characteristics of strain localization, which is considered as aone-dimensional shear problem subjected to normal compressive stress and tangential shear stress.The constitutive relation of rock material is bilinear (elastic and strain softening) and sensitiveto shear strain rate. The solutions proposed based on gradient-dependent plasticity show thatintense plastic strain is concentrated in fault band and the thickness of the band depends on thecharacteristic length of rock material. The post-peak stiffness of the fault band was determinedaccording to the constitutive parameters of rock material and shear strain rate. Fault bandundergoing strain softening and elastic rock mass outside the band constitute a system and theinstability criterion of the system was proposed based on energy theory. The criterion depends onthe constitutive relation of rock material, the structural size and the strain rate. The staticresult regardless of the strain rate is the special case of the present analytical solution. Highstrain rate can lead to instability of the system.