bluuebunny/crossref_metadata_2025 huggingface dataset:
Significance of Population Size on the Fixation of Nonsynonymous Mutations in Genes Under Varying Levels of Selection Pressure
Authors: Subramanian Sankar
Published: January 2013

Previous studies observed a higher ratio of divergences at nonsynonymous and synonymous sites (ω = dN/dS) in species with a small population size compared to that estimated for those with a large population size. Here we examined the theoretical relationship between ω, effective population size (Ne), and selection coefficient (s). Our analysis revealed that when purifying selection is high, ω of species with small Ne is much higher than that of species with large Ne. However the difference between the two ω reduces with the decline in selection pressure (s → 0). We examined this relationship using primate and rodent genes and found that the ω estimated for highly constrained genes of primates was up to 2.9 times higher than that obtained for their orthologous rodent genes. Conversely, for genes under weak purifying selection the ω of primates was only 17% higher than that of rodents. When tissue specificity was used as a proxy for selection pressure we found that the ω of broadly expressed genes of primates was up to 2.1-fold higher than that of their rodent counterparts and this difference was only 27% for tissue specific genes. Since most of the nonsynonymous mutations in constrained or broadly expressed genes are deleterious, fixation of these mutations is influenced by Ne. This results in a higher ω of these genes in primates compared to those from rodents. Conversely, the majority of nonsynonymous mutations in less-constrained or tissue-specific genes are neutral or nearly neutral and therefore fixation of them is largely independent of Ne, which leads to the similarity of ω in primates and rodents.
Organic-inorganic materials to immobilize biological complexes
Authors: Valdez-Castro L. , Méndez-Amaro L. , Mendoza-Serna R. , Ramírez-Castillo M. L. , Ibarra Jorge E
Published: January 2013

In this paper the spore-crystal complex ofBacillus thuringiensis var. israelensis(Bti) was immobilized by the sol-gel process in a hybrid polymer using as precursors the inorganic tetraethyl orthosilicate (TEOS) and the organic Polydimethylsiloxane (PDMS); in order to combine the advantages of both materials in a hybrid matrix to improve aspects such as the thermal stability, the hydrophobic properties and the porosity.Btiproduces different crystals during sporulation phase; these are of protein nature and are used as bio-insecticides. It is important to mention that the insecticide attack is specific to the mosquito larva that causes dengue and black flies. The samples were characterized to ensure viability by performing growth kinetics with fermentations immersed in a flask, this microbial growth was monitored by dry weight, glucose consumption and characterized by Fourier Transform Infrared Spectroscopy (FTIR) to observe the interaction of materials with spore-crystal complex.
Photoacoustic Technique in the Study of Photosynthesis in Aquatic Lirium (Eichhornia Crassipes)
Authors: Calderón A. , Cardona A. , Gracia G. Juárez , Marín E. , Mora Cesar
Published: January 2013

We report, for the first time, the application of the photoacoustic spectroscopy for monitoring the optical absorption spectra in aquatic lirium (Eichhornia Crassipes), before and after it was exposed to ultrasonic irradiations. We obtained a decrease in the amplitude of the bands of the chlorophyllsaandbfor the irradiated samples with ultrasound of 17 kHz and 1.5mW/cm2of power density, and therefore, damage in the centers producing the photosynthesis, due to the irradiation. These results show the utility of the ultrasonic irradiation, as well as, of the photosynthesis monitoring by means of the photoacoustic technique, for the elaboration and establishment of methodologies in the control of this aquatic plant, whose propagation causes many consequences extremely unfavorable for the environment, as well as for the diverse human activities that are developed in the bodies of water in the tropical and sub-tropical regions of the world.
Towards Accurate Spectroscopic Identification of Species at Catalytic Surfaces: Anharmonic Vibrations of Formate on AuPt
Authors: Chan Matthew , Yamashita Koichi , Carrington Tucker , Manzhos Sergei
Published: January 2013

We present a calculation of vibrational frequencies of formate on the AuPt(111) surface alloy including full anharmonicity and coupling of all six intramolecular degrees of freedom. This species is a key intermediate in methanol oxidation on this material. We use a modified version of the method of Manzhos and Carrington to compute the spectrum directly from a small number (<10,000) of DFT single-point energies, bypassing the construction of a potential energy surface. This is the first such calculation for a 4-atomic species at a surface. The spectrum is obtained using rectangular collocation and a small basis set of parameterized Hermite functions. The achievable accuracy of the order of several cm-1 corresponds to the typical experimental resolution. Using normal coordinates makes the equations simple and general and easily applicable to other systems. This calculation is doable on a PC. We predict that anharmonicity and coupling lower the fundamental frequencies by dozens of cm-1, which could affect species assignment.
Thermoelectric properties of Bi-FeSb2 nanocomposites: Evidence for phonon-drag effect
Authors: Pokharel Mani , Koirala Machhindra , Zhao Huaizhou , Lukas Kevin , Ren Zhifeng , Opeil Cyril
Published: January 2013

The thermoelectric properties of Bi-FeSb2 nanocomposites are reported. The electrical resistivity and the Seebeck coefficient measurements show a significant dependence on bismuth concentration. Our results reveal that the shifting of the Seebeck peak in FeSb2 nanocomposites is purely a grain size-effect. The thermal conductivity data indicates a presence of an electron-phonon interaction. Over all, our analysis of the the thermoelectric properties of Bi-FeSb2 nanocomposites provide additional evidence for phonon-drag in FeSb2.
Tantalum Nitride for Copper Diffusion Blocking on Thin Film (BiSb)2Te3
Authors: Hsu H. H. , Cheng C. H. , Lin C. K. , Chen K. Y. , Lin Y. L.
Published: January 2013

This study demonstrates the feasibility of introducing a TaN thin film as a copper diffusion barrier for p-type (BiSb)2Te3 thermoelectric material. Compared to conventional Ni diffusion barrier, remarkably little void generation in Cu bulk or near Cu/TaN interface originated from Cu penetration is observed for TaN barrier after suffering the thermal budget of close to soldering. Diffusion behaviors of the barriers were analyzed by transmission electron microscopy (TEM) and energy dispersive spectrometry (EDS) to make a deep understanding in clarifying interface diffusion effects among the Cu electrode, the barrier layer, and the (BiSb)2Te3thermoelectric layer.
Effects of La0.5Sr0.5CoO3 sol concentration on the microstructure and dielectric properties of Ba0.6Sr0.4TiO3 films prepared by sol-gel method on Ti substrate
Authors: Jiang Dan , Han Songwei , Zhao Xuelian , Cheng Jinrong
Published: January 2013

Ba0.6Sr0.4TiO3 (BST) thin films were deposited on La0.5Sr0.5CoO3 (LSCO) buffered Ti substrates. Both BST and LSCO were prepared by sol-gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis were used to investigate the effect of LSCO sol concentration on the crystallinity and surface morphology of the films. The results show that with the increase of LSCO sol concentration, BST films show variation of the structure and dielectric properties. BST films for LSCO of 0.2 mol/L exhibit a better crystallinity and improved dielectric properties, with the tunability, dielectric constant and tanδ of 30%, 420 and 0.028 respectively.
Influence of microstructure and processing on mechanical properties of advanced Nb-silicide alloys
Authors: Seemüller C. , Heilmaier M. , Hartwig T. , Mulser M. , Adkins N. , Wickins M.
Published: January 2013

In this study different powder metallurgical processing routes, commonly used for refractory metal based materials, were evaluated on their impact on mechanical properties of a multi-component Nb-20Si-23Ti-6Al-3Cr-4Hf (at.%) alloy. Powder was produced by gas-atomization or high energy mechanical alloying of elemental powders and then consolidated either by HIPing or powder injection molding (PIM). The PIM process requires fine particles. In this investigation powder batches of gas-atomized powder (< 25 μm) and mechanically alloyed powder (< 25 μm) were compacted via PIM. Fine (< 25 μm) and coarser (106-225 μm) particle fractions of gas-atomized powder were compacted via HIPing for comparison. Quantitative analysis of the resulting microstructures regarding porosity, phase formation, phase distribution, and grain size was carried out in order to correlate them with the ensuing mechanical properties such as compressive strength at various temperatures.
Semiconductive Properties of Alternating Mg/C Multi-layer Films with Hydroxylation Treatment
Authors: Chiba Masafumi , Endo Daisuke , Haruta Kenichi , Kimura Hideki , Kiyota Hideo
Published: January 2013

A Mg(OH)2–C transparent conductive film was prepared using the sputtering method by the initial formation of a Mg-C film generated by the alternate layering of Mg and C on a rotating substrate and subsequent exposure of the film to atmospheric water vapor. To examine the influence exerted by the Mg/C layers of the starting film sample on semiconductivity,evaluations of the electrical conductivity properties of the film during the hydroxylation process and the optical properties after the hydroxylation process were carried out. As a result, although no effects on the characteristics of the electrical conductivity properties associated with the composition or number of layers in the films could be confirmed, it was determined that the films possessed the characteristics of semiconductors. On the other hand, the optical properties were found to be affected by the composition and number of layers of the Mg/C films.
Chemotaxis of Mesenchymal Stem Cells in a Microfluidic Device
Authors: Choa Ruth , Mehta Manav , Lee Kangwon , Mooney David
Published: January 2013

Adult bone marrow derived mesenchymal stem cells (MSCs) represent an important source of cells for tissue regeneration. Control of MSC migration and homing is still unclear. The goal of this study was to identify potent chemoattractants for MSCs and characterize MSC chemotaxis using a microfluidic device as a model system and assay platform. The three chemokines compared in this study were CXCL7, CXCL12, and AMD 3100.

Microfluidic devices made of polydimethysiloxane (PDMS) were fabricated by soft lithography techniques and designed to generate a stable linear chemokine gradient. Cell movements in response to the gradient were captured by timelapse photos and tracked over 24 hours. Chemokine potency was measured via several chemotaxis parameters including: velocity in the direction of interest (V), center of mass (Mend), forward migration indice (YFMI). The migratory paths of the cells were mapped onto a displacement plot and compared.

The following results were measured in the direction of interest (towards higher concentrations of chemokine): For velocity, only cells exposed to CXCL12 had a statistically significant (p=.014) average velocity (V=0.19 ± 0.07 um/min) when compared to the control condition (V=0.06 ±0 .04 um/min). For the center of mass, where the displacement of cells from their starting positions were compared, again only CXCL12 (Mend= 53.9 ± 10.8 um) stimulated statistically significant (p = .013) displacement of cells compared to the control condition (Mend = 19.3 ± 16.1 um). For the forward migration index, the efficiency of cell movement was measured. Indices in both the CXCL12 (YFIM = 0.19 ± 0.08) and CXCL7 (YFIM = 0.09 ±0.03) conditions were statistically significant (p = .023 for CXCL12 and p = .035 for CXCL7) when compared with the control index (YFIM = .04 ± .02).

This study demonstrated the use of microfluidic devices as a viable platform for chemotaxis studies. A stable linear chemokine gradient was maintained over a long time scale to obtain cell migration results. CXCL12 was quantitatively determined to be the most potent chemoattractant in this research; these chemoattractive properties promote its use in future developments to control MSC homing.
Wafer-Scale, Highly-Ordered Silicon Nanowires Produced by Step-and-Flash Imprint Lithography and Metal-Assisted Chemical Etching
Authors: Ho Jian-Wei , Wee Qixun , Dumond Jarrett , Zhang Li , Zang Keyan , Choi Wee Kiong , Tay Andrew A. O. , Chua Soo-Jin
Published: January 2013

A combinatory approach of Step-and-Flash Imprint Lithography (SFIL) and Metal-Assisted Chemical Etching (MacEtch) was used to generate near perfectly-ordered, high aspect ratio silicon nanowires (SiNWs) on 4" silicon wafers. The ordering and shapes of SiNWs depends only on the SFIL nanoimprinting mould used, thereby enabling arbitary SiNW patterns not possible with nanosphere and interference lithography (IL) to be generated. Very densely packed SiNWs with periodicity finer than that permitted by conventional photolithography can be produced. The height of SiNWs is, in turn, controlled by the etching duration. However, it was found that very high aspect ratio SiNWs tend to be bent during processing. Hexagonal arrays of SiNW with circular and hexagonal cross-sections of dimensions 200nm and less were produced using pillar and pore patterned SFIL moulds. In summary, this approach allows highlyordered SiNWs to be fabricated on a wafer-level basis suitable for semiconductor device manufacturing.
First Investigations on a TNM TiAl Alloy Processed by Spark Plasma Sintering
Authors: Voisin Thomas , Monchoux Jean-Philippe , Clemens Helmut , Couret Alain
Published: January 2013

The processing of a TNM powder (Ti-43.9Al-4Nb-0.95Mo-0.1B, in at.%) by Spark Plasma Sintering (SPS) was investigated for the first time. SPS experiments were performed at varying temperatures. The microstructures of the products were analyzed and interpreted in reference to the available phase diagram. Results of tensile tests conducted at room temperature are also presented.
Briefing: A new tool to analyse forces of discrete-particle media
Authors: del Olmo Daniel , Serrano Alcibíades
Published: January 2013

This paper presents a new tool to analyse the distribution of forces inside discrete-particle media, using a method similar to a stereographic representation, but adding a third dimension associated with the force in the contacts between particles. This tool makes it possible to observe whether a preferential stress path of force distribution exists inside the medium or not. In addition, this tool permits looking inside the medium by knowing the force that is developed along a dip and a dip direction inside it. This new tool is explained and a practice example of application is presented, along with a discussion of the results obtained.
Turbulence schemes for modelling a submerged hydraulic jump
Authors: Raiford John P. , Khan Abdul A.
Published: January 2013

In this paper, a submerged hydraulic jump is modelled using k–ε and renormalisation group (RNG) turbulent schemes with standard coefficients. The computed results of mean and turbulent flow properties for three different cases of inlet Froude number and submergence ratio are compared with the measured data. The results show that the longitudinal velocity profile and its maximum value in the vertical direction are estimated better by the RNG model. Both schemes overpredict the water surface level within the recirculation zone for higher Froude numbers. The longitudinal velocities in the shear layer near the inlet are overpredicted by the two schemes. The longitudinal extent and the magnitude of reverse velocities are predicted well by both schemes. The vertical profiles of kinetic energy per unit mass are predicted well away from the inlet. Near the inlet the trends are predicted well; however, both the magnitude and the height above the bed at which the maximum kinetic energy occurs are overpredicted. The three-dimensional nature of the flow, especially near the inlet is also shown.
Compaction evolution observed via the HVSR of microtremors
Authors: Harutoonian P. , Leo C. J. , Castellaro S. , Zou J. J. , Liyanapathirana D. S.
Published: January 2013

The non-invasive measurement of horizontal to vertical spectral ratio (HVSR) of microtremors is proposed as a means to evaluate field compaction. The HVSR technique is a surface wave method that is quite distinct from the class of array-based surface wave techniques. This is because the basis of the former is the recording and fitting of the HVSR of microtremors, while the latter relies on the recording and fitting of the surface wave velocity dispersion curves of ground vibrations. This paper presents a controlled study of the evolution of compaction, showing it is possible to identify levels of field compaction by observing changes in HVSR data. The results from this study suggest that the fast and operationally simple HVSR technique could be used to assess near-surface ground compaction. It is further envisaged that the technique could be applied to ‘cover the gaps’ left from traditional and expensive invasive techniques (e.g. cone penetration test, standard penetration test, dilatometer test, etc.), particularly for extensive and deep-filled areas such as would occur in dynamically compacted sites.
What data should we collect? A framework for identifying indicators of ecosystem contributions to human well‐being
Authors: Ringold Paul L , Boyd James , Landers Dixon , Weber Matt
Published: January 2013

The lack of a clear framework identifying data to link ecosystems to analyses of human well‐being has been highlighted in numerous studies. To address this issue, we applied a recently developed economic theory termed “final” ecosystem goods and services – the biophysical features and qualities that people perceive as being directly related to their well‐being. The six‐step process presented here enabled us to identify metrics associated with streams that can be used in the analysis of human well‐being; we illustrate these steps with data from a regional stream survey. Continued refinement and application of this framework will require ongoing collaboration between natural and social scientists. Framework application could result in more useful and relevant data, leading to more informed decisions in the management of ecosystems.
Multimodel simulations of forest harvesting effects on long‐term productivity and CN cycling in aspen forests
Authors: Wang Fugui , Mladenoff David J. , Forrester Jodi A. , Blanco Juan A. , Scheller Robert M. , Peckham Scott D. , Keough Cindy , Lucash Melissa S. , Gower Stith T.
Published: January 2013

The effects of forest management on soil carbon (C) and nitrogen (N) dynamics vary by harvest type and species. We simulated long‐term effects of bole‐only harvesting of aspen (Populus tremuloides) on stand productivity and interaction of CN cycles with a multiple model approach. Five models, Biome‐BGC, CENTURY, FORECAST, LANDIS‐II with Century‐based soil dynamics, and PnET‐CN, were run for 350 yr with seven harvesting events on nutrient‐poor, sandy soils representing northwestern Wisconsin, United States. Twenty CN state and flux variables were summarized from the models' outputs and statistically analyzed using ordination and variance analysis methods. The multiple models' averages suggest that bole‐only harvest would not significantly affect long‐term site productivity of aspen, though declines in soil organic matter and soil N were significant. Along with direct N removal by harvesting, extensive leaching after harvesting before canopy closure was another major cause of N depletion. These five models were notably different in output values of the 20 variables examined, although there were some similarities for certain variables. PnET‐CN produced unique results for every variable, and CENTURY showed fewer outliers and similar temporal patterns to the mean of all models. In general, we demonstrated that when there are no site‐specific data for fine‐scale calibration and evaluation of a single model, the multiple model approach may be a more robust approach for long‐term simulations. In addition, multimodeling may also improve the calibration and evaluation of an individual model.
Socioecological revitalization of an urban watershed
Authors: Hager Guy W , Belt Kenneth T , Stack William , Burgess Kimberly , Grove J Morgan , Caplan Bess , Hardcastle Mary , Shelley Desiree , Pickett Steward TA , Groffman Peter M
Published: January 2013

Older, economically troubled urban neighborhoods present multiple challenges to environmental quality. Here, we present results from an initiative in Baltimore, Maryland, where water‐quality improvements were rooted in a socioecological framework that highlighted the interactions between biogeophysical dynamics and social actors and institutions. This framework led to implementation of best management practices followed by assessment of changes in human perception, behavior, and education programs. Results suggest that such an initiative can improve both water quality (eg reductions in nitrogen and phosphorus runoff) and quality of life (eg increased involvement in outdoor recreation by residents and improvements in student environmental literacy and performance) in urban neighborhoods. However, proposed solutions to the water‐quality problems in such neighborhoods have (1) typically emphasized the need for stormwater facilities that are difficult to build and maintain and (2) comprehensively addressed neither the issues related to aging infrastructure and hydrologic complexity nor the benefits derived from linkages between resident perception of environmental improvements and behavior and water‐quality outcomes.
15N isoscapes in a subtropical savanna parkland: spatial‐temporal perspectives
Authors: Bai Edith , Boutton Thomas W. , Liu Feng , Wu X. Ben , Archer Steven R.
Published: January 2013

Spatial patterns of soil δ15N reflect variation in rates of N‐cycling processes across landscapes. However, the manner in which soil δ15N is affected by vegetation and topoedaphic properties under non‐steady state conditions is understood poorly. Here we propose and evaluate a conceptual model that explains how soil δ15N values will respond to changes in disturbance regimes (intensification of grazing and removal of fire) and the resultant invasion of a subtropical grassland by woody vegetation dominated by Prosopis glandulosa (honey mesquite), a N‐fixing tree legume. Spatially‐specific sampling along a catena (hill‐slope) gradient where woody plants are known to have displaced grasses over the past 100 years revealed a positive relationship between soil δ15N and δ13C, and a negative relationship between NDVI and soil δ15N on upland portions of the landscape, indicating that plant cover is a critical determinant of δ15N spatial patterns. Because the dominant woody invader is a N‐fixer, its invasion has increased N input and reduced soil δ15N. However, while honey mesquite also invaded and came to dominate lowland portions of the landscape, soil δ15N values in woodlands of intermittent drainages were significantly elevated relative to those in uplands. This is likely attributable to higher soil moisture, clay content, and total N in the lower portions of the catena gradient, which create conditions favoring more rapid N‐transformation rates, higher preferential 14N losses (e.g., gaseous), and thus enrichment of 15N. Thus, while spatial and temporal variation of soil δ15N has the potential to be an indicator of disturbance‐induced changes in the net N balance, its sensitivity is compromised in topoedaphic settings with where rates of N‐transformation are high. Continued improvements in our understanding of controls over the spatial variability of soil δ15N at the landscape‐scale will enhance our ability to use δ15N as a diagnostic tool for inferring N dynamics under both steady‐state and disturbed conditions.
Optimal Medium Formulation for the Long‐Term Expansion and Maintenance of Human Periodontal Ligament Stem Cells
Authors: Jung Im‐Hee , Kwon Bo‐Sun , Kim Se‐Hee , Shim Hye‐Eun , Jun Choong‐Man , Yun Jeong‐Ho
Published: January 2013

Background: Human periodontal ligament stem cells (hPDLSCs) are promising mesenchymal stem cells that are readily accessible. However, there is as yet no consensus as to the optimal culture medium for hPDLSCs. Thus, the purpose of the present study is to determine the optimal culture medium for long‐term expansion of hPDLSCs.

Methods: hPDLSCs were isolated from healthy third molars, and the most widely used medium formulations in previous studies were used: 1) an α minimum essential medium–based medium formulation (MBM); and 2) a Dulbecco's minimum essential medium‐based medium formulation. Passage 5 (P5) and P8 were evaluated with the two media for cell proliferation, differentiation, and immunophenotype.

Results: hPDLSCs that were primarily cultured in MBM were far more proliferated than those grown in DBM. In general, application of the MBM for longer periods produced greater cell growth and osteogenic differentiation. Furthermore, MBM‐precultured hPDLSCs exhibited a greater degree of cell proliferation and a greater production of mineralized tissue and alkaline phosphatase (ALP) activity in vitro, although the levels of both were dependent on the culture medium used. With respect to long‐term expansion, the P5 hPDLSCs grew and produced the largest amount of mineralized nodules faster than the P8 hPDLSCs, but both passages exhibited a similar phenotype for stemness and ALP activity.

Conclusion: The present study indicates that the inherent capacity of hPDLSCs could be maintained until a later passage, P8 in MBM, and MBM appears to be an optimal choice for manipulating the finest and most stable hPDLSCs.
Discriminant Analysis for the Thin Periodontal Biotype Based on the Data Acquired From Three‐Dimensional Virtual Models of Korean Young Adults
Authors: Lee Seung‐Pyo , Kim Tae‐Il , Kim Hong‐Kyun , Shon Won‐Jun , Park Young‐Seok
Published: January 2013

Background: There have been no objective criteria for classifying the periodontal biotype. The purpose of this study is to suggest clinical guidelines for discriminating the thin biotype, which might be susceptible to gingival recession, using statistical analyses based on the measurement of the dento‐gingival complex on three‐dimensional virtual models.

Methods: From canine to canine, the area of the facial papilla, the facial surface area of the anterior tooth, the proportion of the dento‐papillary complex, clinical papillary length, and the clinical papillary angle were measured on a three‐dimensional virtual model of 133 young participants. In the clinical exam, the gingival transparency when probing was evaluated, and the classification into thin and non‐thin biotype groups was used as the gold standard. The data were analyzed by discriminant analysis.

Results: Twenty‐nine participants (17 males and 12 females) belonged to the “thin group” according to the clinical evaluation. All variables were significantly different between groups (P <0.001). The results of discriminant function analysis showed that the sum of the area between each canine and lateral incisor, each lateral and central incisor, and the two central incisors was the best single determinant of biotype, and the sum of the papillary lengths between each canine and lateral incisor, each lateral and central incisor, and the two central incisors (PLSum5) was the next best choice. The cutoff value of PLSum5 was calculated to be 23.73 mm.

Conclusions: PLSum5 >24 mm is the suggested criterion for identifying high‐risk thin biotype patients based on the comparison with the results from gingival transparency inspection. A clinical reevaluation of this criterion should be examined in additional studies for application in real clinical situations.
Estimation of environmental flow requirements for the river ecosystem in the Haihe River Basin, China
Authors: Yang Tao , Liu Jingling , Chen Qiuying , Zhang Jing , Yang Yi
Published: January 2013

The temporal and spatial environmental flow requirements (EFRs) for the river ecosystem of the Haihe River Basin were analyzed based mainly on the eco-functional regionalization of available water resources. The annual EFRs for the river ecosystem of the Haihe River Basin were 47.71 × 108 m3, which accounted for 18% of the average annual flow (263.9 × 108 m3). The EFRs for river reaches, wetlands, and estuaries were 22.67, 15.32 and 9.72 × 108 m3, respectively. Moreover, the EFRs for the river ecosystem during the wet (June to October), normal (April, May, November), and dry (December to March) periods were 29.99, 9.51 and 8.21 × 108 m3, respectively. Thus, toward a more integrated water resource allocation in the Haihe River Basin, the primary effort should focus on meeting the EFRs for river systems located in protected areas during the dry period.
Degradation of tetracycline in water by ultrasonic irradiation
Authors: Wang Xikui , Wang Yinan , Li Dongliang
Published: January 2013

The objective of this work is to investigate the effectiveness of ultrasonic radiation for the degradation of tetracycline. We analyzed the influence of several operational parameters, including the solution pH, ultrasonic power, initial concentration of tetracycline, H2O2 addition, and the most common anions in surface waters such as bicarbonate, nitrate and sulfate. The results showed that the ultrasonic degradation of tetracycline followed pseudo first-order kinetics. The tetracycline degradation rate is highly pH-dependent and favored at higher pH. The degradation ratio increased with increasing ultrasonic power density, but decreased with increasing the initial concentration of tetracycline. The addition of bicarbonate ions and H2O2 can enhance the degradation rate. No rate variation was observed with the presence of nitrate and sulfate ions.
Water reuse in the Gaza Strip, Palestine
Authors: Vestner R. J. , Brooke K. , Nicolet-Misslbeck L.
Published: January 2013

The Gaza Strip suffers severe constraints in water supply due to its location, confinement, high population density and semi-arid coastal climate. To improve water and agricultural resources, a study was undertaken to show the requirements in planning and management for wastewater treatment, irrigation conveyance and aquifer recharge to meet high technical standards and sustainable economic benefits. Particular attention is paid to economic, financial and socioeconomic analysis. This paper discusses the impact that wastewater reuse will have on the water resources as part of the overall water balance in the Gaza Strip.
Kinetic, isotherm and thermodynamic studies of the adsorption of crystal violet by activated carbon from peanut shells
Authors: Zhang J. X. , Ou L. L.
Published: January 2013

The adsorption of crystal violet dye from aqueous solutions onto an activated carbon prepared from peanut shells was analyzed in this study. The effects of particle size, initial concentration, time and temperature on crystal violet removal were studied in batch experiments. Experimental results showed that the adsorption equilibrium was achieved within 100 min for all studied concentrations. Analysis of adsorption results showed that the adsorption isotherms could be well fitted to the Langmuir model. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients for pseudo first-order and second-order kinetic models were calculated and discussed. The results revealed that the adsorption kinetics was in good agreement with the pseudo second-order equation. Thermodynamic parameters such as the change of Gibbs free energy (ΔG°), change of enthalpy (ΔH°) and change of entropy (ΔS°) have also been determined and it has been found that the adsorption process should be spontaneous, endothermic and physisorption in nature.
Spatial distribution and sources of dissolved trace metals in surface water of the Wei River, China
Authors: Jing Li , Fadong Li , Qiang Liu , Shuai Song , Guangshuai Zhao
Published: January 2013

For this study, 34 water samples were collected along the Wei River and its tributaries. Multivariate statistical analyses were employed to interpret the environmental data and to identify the natural and anthropogenic trace metal inputs to the surface waters of the river. Our results revealed that Zn, Se, B, Ba, Fe, Mn, Mo, Ni and V were all detected in the Wei River. Compared to drinking water guidelines, the primary trace metal pollution components (B, Ni, Zn and Mn) exceeded drinking water standard levels by 47.1, 50.0, 44.1 and 26.5%, respectively. Inter-element relationships and landscape features of trace metals conducted by hierarchical cluster analysis (HCA) identified a uniform source of trace metals for all sampling sites, excluding one site that exhibited anomalous concentrations. Based on the patterns of relative loadings of individual metals calculated by principal component analysis (PCA), the primary trace metal sources were associated with natural/geogenic contributions, agro-chemical processes and discharge from local industrial sources. These results demonstrated the impact of human activities on metal concentrations in the Wei River.
Using wastewater and high-rate algal ponds for nutrient removal and the production of bioenergy and biofuels
Authors: Batten David , Beer Tom , Freischmidt George , Grant Tim , Liffman Kurt , Paterson David , Priestley Tony , Rye Lucas , Threlfall Greg
Published: January 2013

This paper projects a positive outcome for large-scale algal biofuel and energy production when wastewater treatment is the primary goal. Such a view arises partly from a recent change in emphasis in wastewater treatment technology, from simply oxidising the organic matter in the waste (i.e. removing the biological oxygen demand) to removing the nutrients – specifically nitrogen and phosphorus – which are the root cause of eutrophication of inland waterways and coastal zones. A growing need for nutrient removal greatly improves the prospects for using new algal ponds in wastewater treatment, since microalgae are particularly efficient in capturing and removing such nutrients. Using a spreadsheet model, four scenarios combining algae biomass production with the making of biodiesel, biogas and other products were assessed for two of Australia’s largest wastewater treatment plants. The results showed that super critical water reactors and anaerobic digesters could be attractive pathway options, the latter providing significant savings in greenhouse gas emissions. Combining anaerobic digestion with oil extraction and the internal economies derived from cheap land and recycling of water and nutrients on-site could allow algal oil to be produced for less than US$1 per litre.
Characterisation of RO fouling in an integrated MBR/RO system for wastewater reuse
Authors: Moreno J. , Monclús H. , Stefani M. , Cortada E. , Aumatell J. , Adroer N. , De Lamo-Castellví S. , Comas J.
Published: January 2013

Membrane filtration has gradually gained acceptance as the preferred pre-treatment for reverse osmosis (RO). In this paper, an integrated membrane bioreactor (MBR)/RO system for wastewater reuse treating real sewage water has been evaluated and the RO fouling has been characterised. The MBR achieved low values of organic matter, total nitrogen, PO43−, total organic carbon, turbidity and conductivity. Filtration with two different RO commercial membranes was performed after the MBR pre-treatment and the same average fouling rate (0.08 bar day−1) was noted. These results gained from the characterisation of the high quality MBR/RO permeate show its potential for water reuse. Inorganic precipitation appears to be the predominant form of fouling in the RO membranes. Calcium phosphate and alumino-silicates were identified by a scanning electron microscope combined with an energy dispersive X-ray and polysaccharides, amide and aliphatic structures were detected with attenuated total reflection infrared microspectroscopy.
The water footprint of Austria for different diets
Authors: Vanham D.
Published: January 2013

This paper analyses the Austrian water footprint of consumption (WFcons) for different diets: the current diet, a healthy diet (based upon the dietary recommendations issued by the German nutrition society, or DGE), a vegetarian diet and a combined diet between both latter diets. As in many western countries, the current Austrian diet consists of too many products from the groups sugar, crop oils, meat, animal fats, milk, milk products and eggs and not enough products from the groups cereals, rice, potatoes, vegetables and fruit. Especially the consumption of animal products accounts for high WF amounts. These diets result in a substantial reduction (range 922–1,362 l per capita per day (lcd)) of the WFcons for agricultural products, which is currently 3,655 lcd. However, the Austrian water footprint of agricultural production (WFprod = 2,066 lcd) still remains lower than even the WFcons for a vegetarian diet (2,293 lcd). As a result the country is a net virtual water importer regarding agricultural products for all analysed scenarios.
Effects of treated municipal wastewater on fluctuation trend of leaf area index and quality of maize (Zea mays)
Authors: Mousavi Sayed Roholla , Galavi Mohammad , Eskandari Hamdollah
Published: January 2013

The effect of primary-treated municipal wastewater (TMWW) on the leaf area index (LAI) and quality of maize (Zea mays) was studied in comparison to the clean irrigation water (control). The experiment was based on a randomized block design with four replicates, and it was conducted in a field experiment in Aligoudarz (Iran). Irrigation was applied with five different methods as treatments: T1: irrigation with clean water during whole growing period (control); T2: 75% clean water and 25% TMWW; T3: 50% clean water and 50% TMWW; T4: 25% clean water and 75% TMWW; T5: irrigation with TMWW during whole growing period. Results showed that irrigation with TMWW had a significant positive impact on all characters compared with the control. Maximum LAI was yielded on the 80th day after emergence in T4. Use of TMWW increased seed oil to 5.85%, which was 29.2% more than that in the control. Maximum values for percentage of protein, total dry matter and phosphorus concentration were obtained in T5. Maximum zinc concentration (15.93 mg kg−1) was obtained in T4; it was 8% more than the control. According to the results there was no significant difference in treatment T4 and T5.
Modelling the degradation of endogenous residue and ‘unbiodegradable’ influent organic suspended solids to predict sludge production
Authors: Spérandio Mathieu , Labelle Marc-André , Ramdani Abdellah , Gadbois Alain , Paul Etienne , Comeau Yves , Dold Peter L.
Published: January 2013

Activated sludge models have assumed that a portion of organic solids in municipal wastewater influent is unbiodegradable. Also, it is assumed that solids from biomass decay cannot be degraded further. The paper evaluates these assumptions based on data from systems operating at higher than typical sludge retention times (SRTs), including membrane bioreactor systems with total solids retention (no intentional sludge wastage). Data from over 30 references and with SRTs of up to 400 d were analysed. A modified model that considers the possible degradation of the two components is proposed. First order degradation rates of approximately 0.007 d–1 for both components appear to improve sludge production estimates. Factors possibly influencing these degradation rates such as wastewater characteristics and bioavailability are discussed.
Effects of lead(II) on the extracellular polysaccharide (EPS) production and colony formation of cultured Microcystis aeruginosa
Authors: Bi Xiang-dong , Zhang Shu-lin , Dai Wei , Xing Ke-zhing , Yang Fan
Published: January 2013

To investigate the effects of lead(II) on the production of extracellular polysaccharides (EPS), including bound extracellular polysaccharides (bEPS) and soluble extracellular polysaccharides (sEPS), and the colony formation of Microcystis aeruginosa, cultures of M. aeruginosa were exposed to four concentrations (5.0, 10.0, 20.0 and 40.0 mg/L) of lead(II) for 10 d under controlled laboratory conditions. The results showed that 5.0 and 10.0 mg/L lead(II) stimulated M. aeruginosa growth throughout the experiment while 20.0 and 40.0 mg/L lead(II) inhibited M. aeruginosa growth in the first 2 d exposure and then stimulated it. As compared to the control group, significant increases in the bEPS and sEPS production were observed in 20.0 and 40.0 mg/L lead(II) treatments (P < 0.05). Large colony formations were not observed throughout the experiment. However, four tested concentrations of lead(II) could significantly promote the formation of small and middle colonies after 10 d exposure (P < 0.05), and 40.0 mg/L lead(II) had the best stimulatory effect. Lead(II) could stimulate bEPS production, which conversely promoted colony formation, suggesting that heavy metals might be contributing to the bloom-forming of M. aeruginosa in natural conditions.
Ragging phenomenon characterisation and impact in a full-scale MBR
Authors: Gabarrón S. , Gómez M. , Monclús H. , Rodríguez-Roda I. , Comas J.
Published: January 2013

Although there are few studies about clogging phenomenon in the peer-reviewed literature, it is considered one of the main operational challenges by membrane bioreactor (MBR) practitioners. This study presents data from the performance of a full-scale MBR affected by clogging, and ragging in particular. An evaluation of the efficiencies of different applied cleaning methods revealed the acid recovery cleaning to be more efficient than the basic recovery cleanings, although all maintenance cleanings were largely ineffective in recovering membrane permeability. Only declogging cleaning through the manual removal of the accumulated solids was found to be efficient, indicating that such solids were substantially unremoved by chemical cleaning. Moreover, reclogging following manual cleaning demonstrated a propensity for rapid clogging – within a period of 10 days over which the permeability returned to 68 and 88% of the pre-cleaned state. The analysis of the feedwater indicated suspended textile fibres (>70% cotton) to be present at a concentration of more than 40 mg·L−1, ∼90% being smaller than 1 mm (0.06–0.4 mm). These small lengths of filaments evidently pass through pre-treatment and are retained on the membrane surface, forming ‘rags’ within the membrane module, notwithstanding the routine high quality of sludge reflected in the capillary suction time and filterability measurements. Pre-treatment improvement, manual cleaning and permeate flux reduction are the only options to minimise ragging impact over MBR performance.
Optimization of photolysis of diclofenac using a response surface methodology
Authors: Im Jong-Kwon , Kim Moon-Kyung , Zoh Kyung-Duk
Published: January 2013

This study investigates the effects of environmental parameters such as UV intensity (X1, 2.1 ∼ 6.3 mW/cm2), Fe(III) (X2, 0 ∼ 0.94 mg/L), NO3− (X3, 0 ∼ 20 mg/L) and humic acid (X4, 0 ∼ 30 mg/L) on the removal efficiency of diclofenac (DCF, Y), and optimization using a response surface methodology (RSM) based on Box–Behnken design (BBD). According to analysis of variance and t-test results (p < 0.001), the proposed quadratic BBD model based on a total of 29 experimental runs fitted well to the experimental data. Moreover, the determination coefficient (R2 = 0.990) and adjusted determination coefficient (Ra2 = 0.981) indicated that this model is adequate with a high goodness-of-fit. Variables of X1, X2 and X3 had significant positive contributions (p < 0.001), while X4 had significant negative contribution to the DCF removal (p < 0.001). A Pareto analysis showed that X4 was the most important factor (57.18%) in DCF photolytic removal. The predicted and observed DCF removal were 94.98 and 94.2% under optimal conditions (X1 = 6.29 mW/cm2, X2 = 0.75 mg/L, X3 = 15.65 mg/L and X4 = zero), respectively. The RSM not only gives valuable information on the interactions between these photoreactive species (UV intensity, Fe(III), NO3−, and humic acid) that influence DCF removal, but also identifies the optimal conditions for effective DCF removal in water.
Defining cell culture conditions to improve human norovirus infectivity assays
Authors: Straub T. M. , Hutchison J. R. , Bartholomew R. A. , Valdez C. O. , Valentine N. B. , Dohnalkova A. , Ozanich R. M. , Bruckner-Lea C. J.
Published: January 2013

Significant difficulties remain for determining whether human noroviruses (hNoV) recovered from water, food, and environmental samples are infectious. Three-dimensional (3-D) tissue culture of human intestinal cells has shown promise in developing an infectivity assay, but reproducibility, even within a single laboratory, remains problematic. From the literature and our observations, we hypothesized that the common factors that lead to more reproducible hNoV infectivity in vitro requires that the cell line be (1) of human gastrointestinal origin, (2) expresses apical microvilli, and (3) be a positive secretor cell line. The C2BBe1 cell line, which is a brush-border producing clone of Caco-2, meets these three criteria. When challenged with Genogroup II viruses, we observed a 2 Log10 increase in viral RNA titer. A passage experiment with GII viruses showed evidence of the ability to propagate hNoV by both quantitative reverse transcription polymerase chain reaction (qRT-PCR) and microscopy. In our hands, using 3-D C2BBe1 cells improves reproducibility of the infectivity assay for hNoV, but the assay can still be variable. Two sources of variability include the cells themselves (mixed phenotypes of small and large intestine) and initial titer measurements using qRT-PCR that measures all RNA vs. plaque assays that measure infectious virus.
Comparison of the catabolic activity and catabolic profiles of rhizospheric, gravel-associated and interstitial microbial communities in treatment wetlands
Authors: Weber Kela P. , Legge Raymond L.
Published: January 2013

Microbial communities play a critical role in degrading organic contaminants in treatment wetlands; however, an understanding of the different roles played by rhizospheric, gravel-associated and interstitial microbial communities is deficient due to a lack of data directly comparing these microbial communities. Community level physiological profiling (CLPP) was used to compare the catabolic capabilities of rhizospheric, gravel-associated and interstitial microbial communities in vertical-flow planted and unplanted wetland mesocosms. Wetland mesocosms were decommissioned to gather microbial community samples associated with the roots and gravel bed media taken from the top (10 cm depth), middle (30 cm depth) and bottom (60 cm depth). The catabolic capabilities of the rhizospheric microbial communities were seen to be much greater than those of the gravel-associated communities. A decrease in catabolic capability was seen with increasing depth, suggesting that communities near the surface play a larger role in the degradation of carbon-based compounds. A general difference in catabolic profiles based on plant presence/absence was observed for the interstitial water and all gravel-associated samples at all depths, suggesting that the presence of roots within part of the mesocosm not only has a localized effect on the attached microbial population, but also on gravel-associated microbial communities throughout the mesocosms.