bluuebunny/crossref_metadata_2025 huggingface dataset:
Statistical Tests for Detecting Positive Selection by Utilizing High-Frequency Variants
Authors: Zeng Kai , Fu Yun-Xin , Shi Suhua , Wu Chung-I
Published: September 2006

By comparing the low-, intermediate-, and high-frequency parts of the frequency spectrum, we gain information on the evolutionary forces that influence the pattern of polymorphism in population samples. We emphasize the high-frequency variants on which positive selection and negative (background) selection exhibit different effects. We propose a new estimator of θ (the product of effective population size and neutral mutation rate), θL, which is sensitive to the changes in high-frequency variants. The new θL allows us to revise Fay and Wu's H-test by normalization. To complement the existing statistics (the H-test and Tajima's D-test), we propose a new test, E, which relies on the difference between θL and Watterson's θW. We show that this test is most powerful in detecting the recovery phase after the loss of genetic diversity, which includes the postselective sweep phase. The sensitivities of these tests to (or robustness against) background selection and demographic changes are also considered. Overall, D and H in combination can be most effective in detecting positive selection while being insensitive to other perturbations. We thus propose a joint test, referred to as the DH test. Simulations indicate that DH is indeed sensitive primarily to directional selection and no other driving forces.
A Histone Methylation-Dependent DNA Methylation Pathway Is Uniquely Impaired by Deficiency in Arabidopsis S-Adenosylhomocysteine Hydrolase
Authors: Mull Lori , Ebbs Michelle L , Bender Judith
Published: September 2006

S-adenosylhomocysteine hydrolase (SAH) is a key enzyme in the maintenance of methylation homeostasis in eukaryotes because it is needed to metabolize the by-product of transmethylation reactions, S-adenosylhomocysteine (AdoHcy), which causes by-product inhibition of methyltransferases (MTase's). Complete loss of SAH function is lethal. Partial loss of SAH function causes pleiotropic effects including developmental abnormalities and reduced cytosine methylation. Here we describe a novel partial-function missense allele of the Arabidopsis SAH1 gene that causes loss of cytosine methylation specifically in non-CG contexts controlled by the CMT3 DNA MTase and transcriptional reactivation of a silenced reporter gene, without conferring developmental abnormalities. The CMT3 pathway depends on histone H3 lysine 9 methylation (H3 mK9) to guide DNA methylation. Our results suggest that this pathway is uniquely sensitive to SAH impairment because of its requirement for two transmethylation reactions that can both be inhibited by AdoHcy. Our results further suggest that gene silencing pathways involving an interplay between histone and DNA methylation in other eukaryotes can be selectively impaired by controlled SAH downregulation.
Pulmonary Function Assessment in an Infant With Barnes Syndrome: Proactive Evaluation for Surgical Intervention
Authors: Miller Thomas L. , Cox Timothy , Blackson Thomas , Paul David , Weiss Kerry , Shaffer Thomas H.
Published: September 2006

Our aim for this study was to report pulmonary mechanics in a neonate with a severe case of Barnes syndrome, a rare form of thoracolaryngopelvic dysplasia, and to use these data to guide ventilatory support and serve as a presurgical screening tool. A comprehensive pulmonary function evaluation was performed on a 36-day-old patient with Barnes syndrome who was being mechanically ventilated because of severe pulmonary distress secondary to thoracic dystrophy. The measurements consisted of respiratory volumes including functional residual capacity, ventilatory mechanics including compliance and resistance, and thoracoabdominal synchrony. Chest wall compliance was 64% below normal, and the thoracoabdominal motion was indicative of predominantly abdominal displacement during inspiratory breaths. The lungs were functioning at a low functional residual capacity, resulting in low lung compliance and increased pulmonary resistance. As a result of the evaluation, the patient was recommended for lateral thoracic expansion surgery and the ventilatory management was adjusted to focus on end-distending pressure support.
Ablation of Undifferentiated Human Embryonic Stem Cells: Exploiting Innate Immunity Against the Gal α1-3Galβ1-4GlcNAc-R (α-Gal) Epitope
Authors: Hewitt Zoe , Priddle Helen , Thomson Alison J. , Wojtacha Davina , McWhir Jim
Published: September 2006

Although undifferentiated human embryonic stem cells (hESCs) are tumorigenic, this capacity is lost after differentiation, and hESCs are being widely investigated for applications in regenerative medicine. To engineer protection against the unintentional transplantation of undifferentiated cells, we generated hESCs carrying a construct in which the α1,3-galactosyltransferase (GalT) open reading frame was transcribed from the hTERT promoter (pmGT). Because the endogenous GalT gene is inactive, GalT expression was limited to undifferentiated cells. A second chimeric construct (pmfGT) differed by replacement of the GalT leader sequence for that of the fucosyltransferase gene. Two subclones containing stable integrations of pmGT and pmfGT (M2 and F11, respectively) were assessed for their response to human serum containing antibodies to the Galα1-3Galβ1-4GlcNAc-R (α-gal) epitope. The low-variegation line, M2, and to a lesser extent the more variegated line F11, were sensitive to human serum when exposed in the undifferentiated state. However, M2 cells were largely insensitive after differentiation and retained both a normal karyotype and the ability to differentiate into derivatives of the three germ layers in severe combined immunodeficient mice. These data exemplify a method of protection against residual, undifferentiated hESCs prior to engraftment and may provide ongoing immune surveillance after engraftment against dedifferentiation or against de novo tumorigenesis involving hTERT reactivation. Untransfected H9 cells were not sensitive to the human serum used in this study. Hence, in our system, interactions of hESCs with other circulating antibodies, such as anti-Neu5Gc, were not observed.
In Vivo Distribution of Human Adipose-Derived Mesenchymal Stem Cells in Novel Xenotransplantation Models
Authors: Meyerrose Todd E. , De Ugarte Daniel A. , Hofling A. Alex , Herrbrich Phillip E. , Cordonnier Taylor D. , Shultz Leonard D. , Eagon J. Chris , Wirthlin Louisa , Sands Mark S. , Hedrick Marc A. , Nolta Jan A.
Published: September 2006

The potential for human adipose-derived mesenchymal stem cells (AMSC) to traffic into various tissue compartments was examined using three murine xenotransplantation models: nonobese diabetic/severe combined immunodeficient (NOD/SCID), nude/NOD/SCID, and NOD/SCID/MPSVII mice. Enhanced green fluorescent protein was introduced into purified AMSC via retroviral vectors to assist in identification of cells after transplantation. Transduced cells were administered to sublethally irradiated immune-deficient mice through i.v., intraperitoneal, or subcutaneous injection. Up to 75 days after transplantation, tissues were harvested and DNA polymerase chain reaction (PCR) was performed for specific vector sequences as well as for human Alu repeat sequences. Duplex quantitative PCR using human β-globin and murine rapsyn primers assessed the contribution of human cells to each tissue. The use of the novel NOD/SCID/MPSVII mouse as a recipient allowed rapid identification of human cells in the murine tissues, using an enzyme reaction that was independent of surface protein expression or transduction with an exogenous transgene. For up to 75 days after transplantation, donor-derived cells were observed in multiple tissues, consistently across the various administration routes and independent of transduction parameters. Tissue localization studies showed that the primary MSC did not proliferate extensively at the sites of lodgement. We conclude that human AMSC represent a population of stem cells with a ubiquitous pattern of tissue distribution after administration. AMSC are easily obtained and highly amenable to current transduction protocols for retroviral transduction, making them an excellent avenue for cell-based therapies that involve a wide range of end tissue targets.
Catalytic ozonation with metal oxides: an option to control THM formation potential
Authors: Zhang T. , Ma J. , Lu J. , Chen Z. , Li C. , Jiang J.
Published: September 2006

This paper aimed at illustrating the impact of catalytic ozonation on trihalomethane formation potential (THMsFP) of a filtered surface water. Catalytic ozonation with several metal oxides (synthetic α-FeOOH (FeOOH), γ-Al2O3 (Al2O3), CeO2 and MgO) significantly reduced THMsFP of the water compared with ozonation alone. For the FeOOH catalyzed ozonation, several factors, including bromide concentration, pH, alkalinity, ozone dosage, and reaction time, were further studied for their effect on THMsFP of the water. The FeOOH/O3 showed a significant advantage over ozonation in controlling the THMsFP at the applied conditions of bromide (0–3.36 mg/L), pH (6.33–9.43), O3/DOC ratio (0.65–2.05 mg/mg), and reaction time (2–20 min). Increase of bicarbonate alkalinity weakened its advantage. The possible mechanism for the FeOOH/O3 in controlling the THMsFP can be ascribed to higher DOC removal rate and enhanced oxidation of some precursors.
Effects of the filtration flux and pre-treatments on the performance of a microfiltration drinking water treatment system
Authors: Jang Hae-Nam , Lee Dae-Sung , Park Min-Koo , Moon Sun-Young , Cho Soo-Young , Kim Chung-Hwan , Kim Han-Seung
Published: September 2006

This study was performed to investigate the effects of flux and pre-treatment on the operation performance of a microfiltration drinking water treatment system through a pilot scale operation using lake water as raw water. The pilot plant had a capacity of 500 m3/day with a five membrane module and was operated for 1 year to carry out the experiments for the variation of filtration flux, physical cleaning conditions and pre-treatment conditions. Also, an experiment was performed when raw water with high turbidity flowed into the system as well as that pretreated with powdered activated carbon (PAC). When the MF system was operated with filtration flux of 2 m3/m2 day, it could not be operated more than 500 h due to the continuous TMP (Trans-membrane pressure) increase. In case of filtration flux of 1 m3/m2 day, the system could be operated continuously for more than 1300 hours without the increase in the TMP. During this experimentation period, raw water with high turbidity (above 400NTU) was fed into the membrane system. Therefore, the TMP increased by approximately 4.90 kPa compared to the TMP for the previous raw water with lower turbidity. In the case of the PAC pretreated membrane filtration process, the TMP tended to increase slightly. However, the TMP was reduced by performing coagulation and mixing after injecting PAC.
Silica pretreatment for a RO brackish water source with high magnesium
Authors: Chen S. , Chang T. , Lin C.
Published: September 2006

A brackish water source containing high magnesium concentration (333 mg/L as CaCO3) for reverse osmosis (RO) was studied for silica scaling. Threshold limit for RO recovery and required silica removal were firstly determined by a removal–saturation–recovery curve. Three different ratios of lime/soda ash combination were used to test the efficiency of silica removal as well as the impact of calcium and magnesium. Higher pH was more effective for silica removal due to electrostatic attraction since H3SiO−4 and H2SiO−24 were dominant when pH >9.9. The precipitation of Mg(OH)2(s) has assisted more for silica removal than that of CaCO3(s) and the ratio of 0.044 mg SiO2/mg Mg(OH)2(s) and 0.027 mg SiO2/mg CaCO3(s) were statistically determined. Moreover, the presence of high magnesium causes Mg(OH)2(s) to precipitate at lower pH (9.41) instead of formation of forsterite (Mg2SiO4(s)), which typically occurs at pH >12.3. Therefore, no forsterite was observed and was verified by X-ray diffraction (XRD) analysis. Consequently, adsorption is more dominant than chemical reaction in this study. Silica removal was also enhanced by coagulation. With the addition of coagulant (PACl), highest silica removal was achieved at pH of 10, but was decreased when the pH was over 10, due to the amphoteric properties of aluminum hydroxide to reduce the electrostatic attraction to silica at higher pH. Since both softening and coagulation were effective for silica removal, seven decision-making criteria were developed to compare the pros and cons of these two processes.
Comparison of the effects of ozone and permanganate preoxidation on algae flocculation
Authors: Chen Jen-Jeng , Yeh Hsuan-Hsien
Published: September 2006

This study examined how ozone and permanganate preoxidation affect flocculation of Chodatella sp. cultures. Ozone caused cells release of extracellular organic matter (EOM) into the bulk water and altered the cell wall structure, detrimentally affecting algae flocculation. However, permanganate stressed cells, causing them to secrete EOM on cell surfaces, which can improve the absorbability of MnO2 during algae flocculation. In the presence of calcium, algae flocculation after permanganate preoxidation was appreciably increased due to Ca2 +  functioning as a bridging agent between MnO2 and EOM. Algae flocculation was not enhanced in the presence of calcium after ozone preoxidation.
Multivariate statistical techniques for the assessment of surface water quality of Fuji River Basin, Japan
Authors: Shrestha S. , Kazama F.
Published: September 2006

Different multivariate statistical techniques were used to evaluate temporal and spatial variations of surface water-quality of Fuji river basin using data sets of 8 years monitoring at 13 different sites. The hierarchical cluster analysis grouped thirteen sampling sites into three clusters i.e. relatively less polluted (LP), medium polluted (MP) and highly polluted (HP) sites based on the similarity of water quality characteristics. The principal component analysis/factor analysis indicated that the parameters responsible for water quality variations are mainly related to discharge and temperature (natural), organic pollution (point sources) in LP areas; organic pollution (point sources) and nutrients (non point sources) in MP areas; and organic pollution and nutrients (point sources) in HP areas. The discriminant analysis showed that six water quality parameters (discharge, temperature, dissolved oxygen, biochemical oxygen demand, electrical conductivity and nitrate nitrogen) account for most of the expected temporal variations whereas seven water quality parameters (discharge, temperature, biochemical oxygen demand, pH, electrical conductivity, nitrate nitrogen and ammonical nitrogen) account for most of the expected spatial variations in surface water quality of Fuji river basin.
Technical audit of the water distribution network
Authors: Tuhovčák L. , Kučera T. , Ručka J. , Svoboda M. , Sviták Z.
Published: September 2006

This paper outlines one possible approach to the comprehensive technical audit of water distribution networks. Based on practical experience, discussions with domestic and foreign operators, and knowledge gained from international projects, the paper proposes technical indicators, methods for their determination and criteria for evaluating the values reached by these indicators. The proposed procedure is based on the FMEA (Failure Modes Effects and Analysis) method, used in the general theory of risk analysis. The results of this method were employed to evaluate the technical condition of the water distribution network in Pilsen, Czech Republic.
An integrated approach to least-cost planning of water reuse schemes
Authors: Joksimovic D. , Savic D.A. , Walters G.A.
Published: September 2006

Fresh water supplies throughout the world have been getting scarcer over the past few decades. Population and industrial growth leading to an immense increase in the number and intricacy of sources of water pollution, climate change, and shifts in weather patterns towards extremes are just some of the factors that are making the option to reuse water more attractive throughout the world, and necessary for some regions. While there are numerous obstacles to be overcome in planning water reuse schemes, the costs of treatment and distribution are two of the most important factors that need to be considered at the planning level. An additional factor, the selection of end users, also can have significant impact. New decision support software for integrated water reuse, called WTRNet, has been developed, which incorporates these three factors in determining the least-cost design alternatives. A brief overview of existing tools relevant to water reuse is presented, followed by a thorough description of key software features. An application of the WTRNet software on a case study involving a small number of potential industrial users of reclaimed water is presented, which demonstrates the importance of utilizing formal optimisation in determining the most promising design alternatives.
Private participation in China's wastewater service under the constraint of charge rate reform
Authors: Zhong L. , Wang X. , Chen J.
Published: September 2006

China is moving towards a market-based economic system, which includes the water sector. The state is emphasizing tariff reform of the water sector, which is a necessary step in the transition to a market economy, and also an important step for China's wastewater management. With the gradual increase of wastewater service charges, more private investment is attracted to participate, which leads to a decrease in the proportion of direct public investment. This paper develops a model to quantitatively analyse the dependence of private investment on the scale of public investment at different rate levels of wastewater treatment charge. In the meantime, the impacts caused by tax policies on rate level and private sector participation are analysed. In terms of the survey regarding the marketization reform process of the wastewater sector, a summary of the current major public–private partnership (PPP) approaches in China is given in this paper, which reveals that the strategy option also depends on the rate level of the wastewater treatment charge. As a consequence, the government has to keep a greater investment ratio to initiate the market and induct private investment, particularly because the current WWTC rate is at a low level. Furthermore, the BOT-type option is, and still, could be a major form of PPP in China for a while due to the constraint of the current low rate level of the wastewater treatment charge.
Rejection of organic micropollutants by high pressure membranes: comparison of bench-scale versus single element tests
Authors: Kim T.U. , Bellona C. , Xu P. , Drewe J. , Amy G.
Published: September 2006

There has been considerable information reported on rejection of trace organic compounds from pilot-scale and full-scale experiments with reverse osmosis (RO) and nanofiltration (NF), but this information has limited value in predicting the rejection of these compounds by high-pressure membranes. The goal of this research is to define relationships between compound properties, membrane properties, and operational conditions, e.g. pressure, recovery, affecting trace organic compound rejection, comparing bench-scale recirculation tests and bench-scale single-pass tests. In addition, bench-scale results are compared against single element tests to ascertain scale-up effects.
The roles of bromide and precursor structures on DBP formation and species distribution
Authors: Wang G.S. , Huang P.L.
Published: September 2006

This study investigates the role of bromide and the structure of precursors in DBPs formation. Resorcinol (1,3-dihydroxylbenzene) and 2,4-pentadiol were used to represent the aromatic and aliphatic precursors. Laboratory prepared hydrophilic organic acids was used to simulate the mixtures of the aqueous natural organic matter. The results showed that about 60% of the bromide was transformed into HOBr and OBr− by chlorine when the chlorine dosages was high (5–20 mg/L of free chlorine). However, only 20% of bromide was transformed into HOBr and OBr− at low chlorine dosage (1 mg/L). Trihalomethane formation potential (THMFP) measurements showed that higher THMs formation was obtained at higher pH for 2,4-pentadiol, mainly due to the presence of the bromo-THMs. For resorcinol, however, no bromo-THMs are formed at either pH 7 or 9. For THMFP from hydrophilic organic acids, no apparent pH effect was observed. It is concluded that the higher THM formation at higher pH was mainly due to the formation of bromo-THMs from the aliphatic precursors. Similar trends are obtained in THMFP measurements for haloacetic acids formation potential (HAAFP).
The use of enzyme-linked immunosorbent assays (ELISA) for the determination of pollutants in environmental and industrial wastes
Authors: Hirobe M. , Goda Y. , Okayasu Y. , Tomita J. , Takigami H. , Ike M. , Tanaka H.
Published: September 2006

Twelve enzyme-linked immunosorbent assays (ELISA), for the determination of surfactants [linear alkylbenzene sulfonates (LAS), alkyl ethoxylates (AE), and alkylphenol ethoxylates (APE)], endocrine disruptors [alkylphenol (AP), AP + APE, and bisphenol A (BPA)], estrogens [17beta-estradiol (E2), estrone (E1), estrogen (ES: E1 + E2 + estriol (E3)), 17alfa-ethynylestradiol (EE2)], dioxins and polychlorinated biphenyls (PCBs), were validated on environmental water and industrial wastes. The lowest quantification limits of these ELISAs were 0.05 μg/L (BPA, E2, E1, ES and EE2), 2 μg/L (AE), 3 μg/L (dioxins and PCBs), 5 μg/L (AP, AP + APE) and 20 μg/L (LAS and APE). To apply these ELISAs to environmental or industrial waste samples, simple and appropriate pre-treatment methods were also developed for each ELISA. With optimized pre-treatments, the values of ELISAs were well co-related, in all cases, to those of instrumental analytical methods such as liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry (LC-MS/MS), and high-resolution gas chromatography mass spectrometry (HR-GC-MS), etc.
The expanded bed biofilter: combined nitrification, solids destruction, and removal of bacteria
Authors: Dempsey M.J. , Porto I. , Mustafa M. , Rowan A.K. , Brown A. , Head I.M.
Published: September 2006

Developed for tertiary nitrification, this biofilter also removed carbonaceous BOD (cBOD) and (SS). Because the biofilter is expanded, it cannot clog, and therefore does not require backflushing; yet, it removed a significant proportion of the influent SS. This unanticipated capability was due to the activities of heterotrophic bacteria, protozoa, and metazoa (nematode and oligochaete worms). The expanded bed is an intensified process, which is based on natural immobilization of microbes to small support particles. Using glassy coke as the support material, an attached layer of microbes develops, forming particulate biofilms having a superficial surface area of 1 800 m2 m−3expanded bed. Autotrophic nitritifiers (Nitrosomonas spp.) were detected in the biofilm using rRNA-based molecular methods and were likely responsible, at least in part, for reducing the ammonia concentration by up to 99% (to 0.1 mg L−1), while the other organisms reduced cBOD and SS by up to 56% and 62%, respectively. Furthermore, the influent concentrations of Escherichia coli, coliform and heterotrophic bacteria were reduced by over 80%. It thereby provides a single process solution for combined tertiary nitrification and solids removal. Operating the process to consistently achieve <0.5 mg NH3N L−1 and at the same time removing a significant fraction of cBOD and SS, it can replace processes such as SAFs or NTFs followed by a sandfilter.
Surfactant effects on alpha factors in full-scale wastewater aeration systems
Authors: Rosso D. , Larson L.E. , Stenstrom M.K.
Published: September 2006

Aeration is an essential process in the majority of wastewater treatment processes, and accounts for the largest fraction of plant energy costs. Aeration systems can achieve wastewater oxygenation by shearing the surface (surface aerators) or releasing bubbles at the bottom of the tank (coarse- or fine-bubble aerators). Surfactants accumulate on gas–liquid interfaces and reduce mass transfer rates. This reduction in general is larger for fine-bubble aerators. This study was conducted to evaluate mass transfer effects on the characterization and specification of aeration systems in clean and process water conditions. Tests at different interfacial turbulence regimes were analysed, showing higher gas transfer depression for lower turbulence regimes. Higher turbulence regimes can offset contamination effects, at the expense of operating efficiency. This phenomenon is characteristic of surface aerators and coarse bubble diffusers and is here discussed. The results explain the variability of α factors measured at small scale, due to uncontrolled energy density. Results are also reported in dimensionless empirical correlations that describe mass transfer as a function of physiochemical and geometrical characteristics of the aeration process.
Benchmark Simulation Model No 2 in Matlab-Simulink: towards plant-wide WWTP control strategy evaluation
Authors: Vrecko D. , Gernaey K.V. , Rosen C. , Jeppsson U.
Published: September 2006

In this paper, implementation of the Benchmark Simulation Model No 2 (BSM2) within Matlab-Simulink is presented. The BSM2 is developed for plant-wide WWTP control strategy evaluation on a long-term basis. It consists of a pre-treatment process, an activated sludge process and sludge treatment processes. Extended evaluation criteria are proposed for plant-wide control strategy assessment. Default open-loop and closed-loop strategies are also proposed to be used as references with which to compare other control strategies. Simulations indicate that the BM2 is an appropriate tool for plant-wide control strategy evaluation.
Benchmarking of WWTP design by assessing costs, effluent quality and process variability
Authors: Benedetti L. , Bixio D. , Vanrolleghem P.A.
Published: September 2006

Process choice and dimensioning of WWTPs is a particularly sensitive step to cost-efficiently comply with regulatory standards. This step accounts only for a small fraction of the upfront costs, but it can lead to substantial savings. This paper illustrates the results of a systematic methodology to evaluate system design/upgrade options. In contrast to conventional practice, this approach allows the choice between the most appropriate trade-off between cost of measures and effluent quality, and to assess the reliability of a process layout. It is therefore a flexible instrument to cope with the flexibility and complexity of integrated water management regulations. Results show good agreement of the simulations with extensive benchmarking studies on actual plants. For that reason, the suggested methodology can provide valuable support also to such practices.
Behaviour of arsenic species in batch activated sludge process: biotransformation and removal
Authors: Andrianisa H.A. , Ito A. , Sasaki A. , Ikeda M. , Aizawa J. , Umita T.
Published: September 2006

The behaviour of As(III), As(V), MMAv and DMAv in batch activated sludge process were investigated. Experiments were carried out by using aerobic and anoxic reactors with an initial As concentration of 100 μg l−1. Under aerobic condition, As(III) was oxidized to As(V) within 9 hours, some part of MMAv was methylated to DMAv and some other part was demethylated to As(III), which in turn was immediately oxidized to As(V). Under anoxic condition, As(V) was reduced to As(III) within the same time-course. No significant transformation occurred during experiments conducted with DMAv. It was found that all reactions were biologically mediated. The overall As removal was low (<20%) during the experiments. Although a relationship seems to exist between the sludge concentration and As removal, it is concluded, under the conditions of our study, that the activated sludge process cannot remove arsenicals efficiently. However, it can control their transformations well. Thus, if associated with an appropriate technology, the activated sludge can be used for As pre-oxidation to treat As contaminated wastewaters. Finally, care must be taken on possible presence of MMAv in the influent of any wastewater treatment plant as it can be easily oxidized by the activated sludge.
Strategy and current status of combating eutrophication in two Berlin lakes for safeguarding drinking water resources
Authors: Schauser I. , Chorus I. , Heinzmann B.
Published: September 2006

After reduction of the external phosphorus load by phosphorus elimination plants, Lake Tegel and Schlachtensee in Berlin underwent a significant trophic improvement. The phosphorus elimination plants work by precipitation/coagulation/flocculation – sedimentation – post precipitation – filtration. The external load was reduced by one to two orders of magnitude down to 10–20 μg P L−1.The inlake phosphorus concentration followed. The development of algae and cyanobacteria was reduced substantially below a threshold value of about 50 μg P L−1, clearly due to phosphorus limitation. In Lake Tegel, the external load reduction of the main inflow was counteracted partially by the external load of the second main inflow by the River Havel and the internal load. This has to be managed further in future.
Modelling of sediment oxygen demand and organic flux for a pulsed sediment organic load
Authors: Wang Y.X. , Li X.Y. , Lee J.H.W.
Published: September 2006

Biodegradation of organic matter in the sediment affects both the level of dissolved oxygen (DO) in the overlaying water and material flux into the water body. In the present study, a mathematical model was developed to describe the DO dynamics and related organic transformation in the sediment after a pulsed load of rich organic, sediment. The model includes DO diffusion at the sediment–water interface and inside the sediment, diagenetic reactions of particulate organic to soluble organic, substances, biodegradation of soluble organic, and related DO consumption. The model can simulate sediment oxygen demand (SOD) in a dynamic system after a sudden organic load on the sediment and the flux of both biodegradable and non-biodegradable organic can be predicted. In addition, laboratory experiments were conducted using SOD chambers to investigate the SOD dynamics and sediment material fluxes. The sediment of the batch SOD tests was loaded with fish food at various rates for the sudden organic input. Numerical simulations for SOD and organic fluxes compared well with the experimental measurements. The results demonstrate that the model can be used to predict the effect of sediment pollutants on the water quality of surface waters.
Efficiencies of residual organic pollutants removal from secondary effluent by switching of coagulation–air flotation–filtration processes
Authors: Huang R. , Zhang J. , Ma L. , Jiang A. , Kong X.J. , Li X.K. , Bao L.
Published: September 2006

It is an essential task to remove the residual organic pollutants (ROP) from secondary effluent of a Wastewater Treatment Plant (WWTP) in wastewater reclamation and reuse processes. Four different compared flow schemes would be achieved for further purification of the secondary effluent by switching of different valves. In order to mainly remove non-biodegradable residual organic pollutants under various operating conditions, the optimum technology and economic process was obtained in the advanced purification flow scheme at a flow of 3200 m3/d in Harbin Wenchang WWTP. Conclusions under a lot of experiments show that: choosing the coagulation-settler plus biofilm filter for advanced purification process is reasonable; during the stable operation phase, this process showed good performance in removing the COD, BOD5, TP, NH3-N and SS; the removal rates are 50%, 39%, 67%, 50%, 80% respectively. The effluent is able to excel the requirements for wastewater reuse standards. The unit cost of the water is 0.542 yuan/m3, which is far below the fee paid for supply water, long-distance transfer water or seawater desalination through economic analysis.
Modeling biodegradation of toluene in rotating drum biofilter
Authors: Yang C.P. , Chen H. , Zeng G.M. , Qu W. , Zhong Y.Y. , Zhu X. , Suidan M.T.
Published: September 2006

Rotating drum biofilters (RDBs) are cost-effective for control of emissions of volatile organic compounds (VOCs) from waste gas streams. In this paper, a dynamic mathematical model is presented which simulates and predicts the variation in performance of a multi-layer RDB with time on the basis of the two-film theory. The model takes into account factors including biofilm growth and biomass loss, and a changing biofilm surface area and thickness assuming quasi-steady-state conditions in the two-phase system and uniform bacterial population. Toluene was assumed to be the only rate-limiting substrate. The model equations for the gas-phase mass balance and biofilm growth were solved using MATLAB based on the fourth-fifth-order Runge–Kutta technique, and the concentration profiles in the biofilms were obtained using the method of orthogonal collocation. Simulation results showed that the toluene removal efficiency decreased with increased toluene loading or increased duration of operation of the biofilter. Calculation results were compared to the experimental results, which demonstrated that the dynamic model provided a good simulation of the performance of the biofilter.
New compact scrubber for odour removal in wastewater treatment plants
Authors: Sanchez C. , Couvert A. , Laplanche A. , Renner C.
Published: September 2006

This work presents the performances of a new odour scrubber. The reactor is packed with a new structure which enables co-current operations at high gas velocities. Energy consumption and removal efficiency of sulphur compounds by oxidative alkaline scrubbing were studied. The influence of both superficial gas (USG) and liquid (USL) velocities, ranging from 5.6 to 28 m.s−1 and 0.016 to 0.055 m.s−1 respectively, were quantified. Thus, the range of 0.5 to 5 liquid-to-gas mass ratio (L/G) was studied. A comparison has been made with a previous study on static mixers (SM) and with classical random packed towers (PT). It has been shown that superficial liquid and gas velocities have a significant influence on these parameters. Hydrogen sulphide (H2S) abatement reached values up to 99%. As concerns methylmercaptan (CH3SH), the maximal removal efficiency was 87%. As a result, if well scaled-up, our reactor can be a small single stage efficient apparatus for the elimination of low concentrations of sulphur compounds as H2S and CH3SH in high flow rates of polluted gas effluents.
Chemical stress induced by copper: examination of a biofilm system
Authors: Zhang X. , Brussee K. , Coutinho Caroline T. , Rooney-Varga J.N.
Published: September 2006

Biofilm systems have been widely used in wastewater treatment plants. However, little information is available on the impact of toxic chemicals on the performance of fixed film systems. This study was aimed at evaluating the impact of copper on a biofilm system by examining a variety of parameters, including reactor pH, DO, substrate concentrations, secretion of extracellular polymeric substances (EPS), and copper removal and accumulation. The microbial communities in the biofilms were also examined using automated ribosomal intergenic spacer analysis (ARISA). Four rotating drum biofilm reactors were used to produce biofilms. One reactor was used to produce biofilms under copper free conditions; while the others were used to produce biofilms grown under three different copper contamination levels, namely 100 ppb, 200 ppb, and 500 ppb, for a prolonged period. The following results were obtained: (1) biofilm reactor performance was not significantly impacted as demonstrated by the pH, DO, substrate removal, and total solids in the effluent; (2) however, copper contamination inhibited EPS production in the biofilms; (3) copper removal efficiencies of 25–31% were obtained for the three copper contamination levels studied; (4) fixed films functionalized as a reservoir to accumulate more copper over time; and (5) copper contamination selected for specific species that were able to tolerate this stress and that may contribute to its remediation.
Instrumentation, control and automation for full-scale manure-based biogas systems
Authors: Wiese J. , Haeck M.
Published: September 2006

In recent years manure-based biogas plants (MBBP) have won more and more importance, because of the numerous ecological advantages. The processes are similar to processes, which have been well known for many decades in anaerobic wastewater/sludge treatment. As a result of technical progress and permanently rising prices for non-renewable energy, MBBPs have become more and more economically reasonable. Because of the economies of scale law more and more larger MBBPs are being built (250–2000 kWel). With regard to investment costs, reactor volumes and complexity etc., these (centralized) plants are comparable with small wastewater treatment plants (WWTP). Consequently, as actually in the case of the small WWTPs a rising use of instrumentation, control and automation (ICA) for larger MBBPs can be observed.
Experimental study on sludge reduction by ultrasound
Authors: Cao X.Q. , Chen J. , Cao Y.L. , Zhu J.Y. , Hao X.D.
Published: September 2006

In recent years, considerable impetus emerges to develop strategies for reducing excess sludge produced in biological wastewater treatment (BWT) systems. In this study, an experiment on sludge reduction by ultrasound treatment was conducted. The influences of sonication on observed yield, sludge reduction, effluent quality, sludge settleability and stability were extensively evaluated. It was found that ultrasound had an impressive potential to reduce sludge production. Moreover, it was also concluded that a treatment time of 10 minutes was more cost-effective for sludge reduction, and a reduction by 44% was reached with an ultrasonic intensity of 0.25 w/ml. The reduction could be mainly attributed to disintegration of bio-flocs and cryptic growth. In addition, sonication time seemed to be more effective to reduce sludge production compared with ultrasonic intensity. Slight deterioration of the effluent quality and some variations of the sludge settleability and stability were observed after ultrasound treatment.
Effect of starvation on activity and viability of Pseudomonas aeruginosa ATCC 10145 degrading 4-chlorophenol
Authors: Moreno-Andrade I. , Lopez-Vidal Y. , Buitrón G.
Published: September 2006

The evolution of degradsation capacity and in the viability of Pseudomonas aeruginosa ATCC 10145 acclimated to 25 mg4CP/L degradation and, later, exposed to starvation periods of 24, 48, 72, 96, 132 and 156 hours was studied. Degradation rate heterotrophic plate count and cell cytometry were used to evaluate the starvation influence. Results demonstrated that the exposition of P. aeruginosa to starvation produces a decrease in the viability and activity for the degradation of 4-chlorophenol.
The benefits of drinking water quality regulation – England and Wales
Authors: May A.
Published: September 2006

This paper aims to demonstrate that the regulation of drinking water quality in England and Wales has been successful in securing the improvements to drinking water quality resulting in better performance against EU and national standards. The water industry in England and Wales went through a major change in 1989 when suppliers were privatised and the government set up a robust regulatory regime. The regime was necessary as the industry was, as a result of privatisation, a monopoly with customers having no choice of supplier, unlike what was later available with other utilities such as gas or electricity. The regime would protect the interests of the consumer, the environment and public health through the quality of the product. The Drinking Water Inspectorate (DWI), as established in 1990, had to ensure the implementation of the European Drinking Water Directive (DWD) that had been transposed into national legislation. The aim of the DWD is to ensure that all EU Member States provide drinking water of a prescribed quality. In England and Wales, a body was required to oversee the performance of the industry against those standards, reporting to the Government and the European Commission.

Through acts and legislation, the set up of the industry, the duties of the suppliers and regulators and the powers available to the regulators were established. The improvements to drinking water quality since privatisation were achieved by massive investment of the privatised water industry overseen by an independent regulator with clear duties and the powers to inspect, enforce and prosecute. The DWI's achievements show that to improve quality performance with the ability to report in detail how the improvements were made with extensive data evidence, a special regulator is required. The DWI advises policy departments and Ministers and when there are serious concerns regarding a threat to human health through drinking water, the highest level of regulatory power is the creation of new legislation, for example, the Cryptosporidium regulations that are unique to the UK. The DWI is more than what is traditionally thought of as a regulator because it has a single remit — drinking water quality — and its style of regulation has been key to improved drinking water quality in England and Wales.
Simulation of fast reactions in batch reactors under sub‐critical water condition
Authors: Abdelmoez Wael , Yoshida Hiroyuki
Published: September 2006

In this study the temperature profiles inside a tube batch reactor under the sub‐critical water condition were investigated under different operating conditions. The most important parameters that may affect the temperature profile, including salt bath mixing speed, reactor shaking, reactant viscosity, and reactor contents, were investigated both experimentally and theoretically. The results showed that both salt bath mixing and reactor shaking had a great effect in the rate of heating up. The study of the effect of reactant viscosity on the temperature profile revealed that the thermal conductivity rather than viscosity was found to affect the temperature profile in the case of comparing reactant with different viscosities. The reactant contents had the lowest pronounced effect on both heating up and cooling down rates among all tested parameters. Two different empirical equations were developed to describe the temperature profiles during both heating up and cooling down periods. Using these equations we developed a new mathematical model for describing the kinetic behavior of fast reactions that take place under the sub‐critical water condition. We assumed that the reaction was taking place under unsteady state conditions and following first order kinetics. Based on the simulation results, we developed a new strategy for finding out the correct values of activation energy and frequency factor involved in such fast reactions. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Polypeptides and 100 Years of Chemistry of α‐Amino Acid N‐Carboxyanhydrides
Authors: Kricheldorf Hans R.
Published: September 2006

Syntheses and polymerizations of α‐amino acid N‐carboxyanhydrides (NCAs) were reported for the first time by Hermann Leuchs in 1906. Since that time, these cyclic and highly reactive amino acid derivatives were used for stepwise peptide syntheses but mainly for the formation of polypeptides by ring‐opening polymerizations. This review summarizes the literature after 1985 and reports on new aspects of the polymerization processes, such as the formation of cyclic polypeptides or novel organometal catalysts. Polypeptides with various architectures, such as diblock, triblock, and multiblock sequences, and star‐shaped or dendritic structures are also mentioned. Furthermore, lyotropic and thermotropic liquid‐crystalline polypeptides will be discussed and the role of polypeptides as drugs or drug carriers are reviewed. Finally, the hypothetical role of NCAs in molecular evolution on the prebiotic Earth is discussed.
Synthesis of novel zirconium complexes bearing mono‐Cp and tridentate Schiff base [ONO] ligands and their catalytic activities for olefin polymerization
Authors: Chen Qihui , Huang Jiling
Published: September 2006

A series of novel zirconium complexes {R2Cp[2‐R1‐6‐(2‐CH3OC6H4NCH)C6H3O]ZrCl2 (1, R1 = H, R2 = H, 2: R1 = CH3, R2 = H; 3, R1 = tBu, R2 = H; 4, R1 = H, R2 = CH3; 5, R1 = H, R2 = n‐Bu)} bearing mono‐Cp and tridentate Schiff base [ONO] ligands are prepared by the reaction of corresponding lithium salt of Schiff base ligands with R2CpZrCl3·DME. All complexes were well characterized by 1H NMR, MS, IR and elemental analysis. The molecular structure of complex 1 was further confirmed by X‐ray diffraction study, where the bond angle of ClZrCl is extremely wide [151.71(3)°]. A nine‐membered zirconoxacycle complex Cp(O2C6H4NCHC6H4‐2O)ZrCl2 (6) can be obtained by an intramolecular elimination of CH3Cl from complex 1 or by the reaction of CpZrCl3·DME with dilithium salt of ligand. When activated by excess methylaluminoxane (MAO), complexes 1–6 exhibit high catalytic activities for ethylene polymerization. The influence of polymerization temperature on the activities of ethylene polymerization is investigated, and these complexes show high thermal stability. Complex 6 is also active for the copolymerization of ethylene and 1‐hexene with low 1‐hexene incorporation ability (1.10%). Copyright © 2006 John Wiley & Sons, Ltd.
Heterogeneous postnatal transitions in myosin heavy chain isoforms within the rabbit temporalis muscle
Authors: Korfage Joannes A.M. , Van Wessel Tim , Langenbach Geerling E.J. , Van Eijden Theo M.G.J.
Published: September 2006

Postnatal changes in the fiber type composition and fiber cross‐sectional area were investigated in the superficial (TEM1) and deep (TEM23) temporalis of male rabbits. It was hypothesized that, due to the transition from suckling to chewing during early postnatal development, the proportion of fast fiber types would decrease, while the proportion of fibers positive for myosin heavy chain (MyHC) cardiac α would increase, and that, due to the influence of testosterone during late postnatal development, the proportion of these α fibers would decrease again. Classification of the fibers types was performed by immunohistochemistry according to their MyHC content. The proportion of α fiber types significantly increased in both muscle portions from 2% and 8% for TEM1 and TEM23 at week 1 to 29% and 54% at week 8, respectively,. While in TEM1 the proportion of this fiber type did not change thereafter, it decreased again to 27% in TEM23 at week 20. The change for the fast fiber types was opposite to that of the α fiber types. Significantly more MyHC IIX fibers were found in TEM1 than in TEM23 in adult rabbits. In the first 8 weeks, the cross‐sectional areas of all fibers increased. After this period, only MyHC cardiac α + I fibers continued to increase significantly. It was concluded that there are developmental differences in the myosin heavy chain transitions of the two portions of the temporalis muscle. Anat Rec Part A, 288A:1095–1104, 2006. © 2006 Wiley‐Liss, Inc.