bluuebunny/crossref_metadata_2025 huggingface dataset:
TEM Study on Defects in Epitaxial CdZnTe Films Deposited on (001)GaAs by Close-Spaced Sublimation
Authors: Gao Junning , Jie Wanqi , Luo Lin , Yuan Yanyan , Wang Tao , Xi Shouzhi , Yu Hui
Published: October 2012

A transmission electron microscopy (TEM) study on defects in a 30 μm-thick epitaxial CZT film deposited on (001)GaAs via close-spaced sublimation was performed. The epi-layer is of good quality without twins. Dislocations and stacking faults are mainly gathered near the interface. The dislocations are extrinsic either of Lomer edge or 60° type. Pseudo extrinsic stacking faults consisting of two independent and oppositely oriented extrinsic dislocations have been found both on the (111) and the $(\bar 1\bar 11)$ planes. L-shaped defects originated from the interface have been discovered. The near-interface-side of L is consisted of 3 compressed (111) planes and the lateral side is consisted of 3-4 misarranged $(\bar 1\bar 11)$ planes. This L-shaped defect is induced by the absence of a misfit dislocation at the intersection between L and the interface.
High-Irradiance Degradation Studies of Metamorphic 1eV GaInAs Solar Cells
Authors: France Ryan M. , Steiner Myles A.
Published: October 2012

Initial tests are performed regarding the degradation of lattice-mismatched GaInAs solar cells. 1eV metamorphic GaInAs solar cells with 1-2×106 cm-2 threading dislocation density in the active region are irradiated with an 808 nm laser for 2 weeks time under a variety of temperature and illumination conditions. All devices show a small degradation in Voc that is logarithmic with time. The absolute loss in performance after 2 weeks illuminated at 1300 suns equivalent and 125°C is 7 mV Voc and 0.2% efficiency, showing these devices to be relatively stable. The dark current increases with time and is analyzed with a two-diode model. A GaAs control cell degrades at the same rate, suggesting that the observed degradation mechanism is not related to the additional dislocations in the GaInAs devices.
Assessment of Photovoltaic Junction Position in CdTe Solar Cells Using a Combined FIB-EBIC Technique
Authors: Major Jonathan D. , Bowen Leon , Treharne Robert E. , Durose Ken
Published: October 2012

Two issues relating to the determination of junction position in thin film CdTe solar cells have been investigated. Firstly, the use of a focussed ion beam (FIB) milling as a method of sample preparation for electron beam induced current (EBIC) analysis is demonstrated. It is superior to fracturing methods. High quality secondary electron and combined secondary electron/EBIC images are presented and interpreted for solar cells with CdTe layers deposited by both close space sublimation (CSS) or RF sputtering. Secondly, it was shown that in an RF-sputtered CdTe device, while the photovoltaic junction was buried ~1.1 μm from the metallurgical interface, the shape of the external quantum efficiency (EQE) curve did not indicate the presence of a buried homo-junction. SCAPS modelling was used to verify that EQE curve shapes are not sensitive to junctions buried < 1.5μm from the CdTe/CdS interface.
Free standing GaN nano membrane by laser lift-off method
Authors: Tang Liang , Wang Yuefeng , Cheng Gary , Manfra Michael J. , Sands Timothy D.
Published: October 2012

In this work, we present a method able to fabricate thin GaN nanomembranes fit for device applications. Starting from commercial GaN on sapphire substrates, MBE was used to deposit a sacrificial layer, which comprises of a superlattice of InN/InGaN, after which thin a GaN film of hundreds of nanometers thickness was grown on top. Pulsed laser irridiation with photon energy of 2.3eV gives rise to the controlled decomposition of the sacrificial intermediate layer, which can be followed by easy separation of the top GaN membrane from the substrate. This process can be used to manufacture GaN membranes with low defect density and a wider range of thickness. We demonstrated that large area, free-standing GaN membranes, with a thickness from 200nm and up, could be made using this method, and the high crystal quality of the lift-off GaN layers is well preserved in this process.
Temperature Dependent Characterization of Imbedded InAs Quantum Dots in GaAs Superlattice Solar Cell Structures by High Resolution X-ray Diffraction
Authors: Sheng Josephine J. , Chapman David. C. , Wilt David M. , Polly Stephen J. , Bailey Christopher G. , Kerestes Christopher , Hubbard Seth M. , Han Sang M.
Published: October 2012

The insertion of nanostructured materials (such as quantum wells, wires, and dots) into the intrinsic region of p-i-n solar cells introduces an intermediate band within the bandgap of the host material. It has been shown that the sub-bandgap conversion provided by the nanostructured materials, enhances the short circuit current as well as the overall efficiency of InAs quantum dots (QD) imbedded in GaAs superlattice (SL) solar cells [1]. As a contender for space applications, it is necessary to subject these solar cell structures to temperatures encountered in the Low Earth Orbit (LEO), probing for any material degradation. Herein, we focus on temperature dependent characterization using high resolution X-ray diffraction (HRXRD) of InAs QD enhanced GaAs solar cell structures with varying growth parameters. The structures characterized can be classified into three groups: (1) GaP strain compensation coverage, (2) GaAs barrier coverage, and (3) InAs coverage for QD formation. HRXRD rocking curves of each structure focusing around the GaAs peak are analyzed at a range of temperatures up to 200˚C. Although no noticeable shifts in the SL peaks are detected, interfacial diffusion decreased the resolution of fringes produced by reflections at the SL interfaces in test structures with varying InAs QD coverage. Unbalanced strain in the same structures shows a distortion in the GaAs peaks.
Enhanced Light Absorption in Textured Metal Organic Chemical Vapour Deposited (MOCVD) CdO Thin Films
Authors: Adekoya Sunday O. , Eleruja Marcus A. , Olofinjana Bolutife , Akinwunmi Olumide O. , Taleatu Bidini A. , Ajayi Ezekiel O. B.
Published: October 2012

The Single Solid Source precursor Cadmium Acetylacetonate, Cd[C5H7O2]2 was prepared and Cadmium Oxide thin films were deposited on Sodalime glass substrate using Metal Organic Chemical Vapour Deposition (MOCVD) technique at deposition temperature of 420 oC The films were characterized using Scanning Electron Microscopy (SEM) with Energy Dispersive XRay (EDX) facility attached to it, X-Ray Diffractometry (XRD) and UV-visible spectrometry. SEM micrographs showed the formation of textured surface with identifiable cubic and hexagonal structures, having average grain size greater than 1 μm. XRD studies indicated the formation of polycrystalline cubic CdO phase with preferred orientation in (111) plane. A direct optical band gap of 2.10 eV was obtained from the analysis of the UV-visible spectrum with an enhanced light absorption in 750 – 1000 nm spectrum range. This enhancement is as a result of light trapping by the textured crystalline structure.
Feedback and Inflation Mechanism in Successive Multiphonon Carrier Captures at Deep-level Defects
Authors: Suzuki Kei , Wakita Masaki , Shinozuka Yuzo
Published: October 2012

Possibility of feedback and inflation mechanism among carrier captures by a deep-level defect and transient induced lattice vibrations is discussed using proper configuration coordinate diagrams for many carriers. Treating the lattice motion classically we selfconsistently simulate the time evolution of the interaction mode and a series of athermal captures of electron(s) and hole(s). When both the activation energies Eacte and Eacth are small, a series of successive athermal captures is enhanced and probable for high carrier densities, however, we find that the possibility of inflation in the amplitude of the lattice vibration critically depends on the minority capture rate and the relative width of the phonon frequency distribution.
Recent Reliability Progress of GaN HEMT Power Amplifiers
Authors: Ohki Toshihiro , Kanamura Masahito , Kamada Yoichi , Makiyama Kozo , Inoue Yusuke , Okamoto Naoya , Imanishi Kenji , Joshin Kazukiyo , Kikkawa Toshihide
Published: October 2012

In this paper, we describe highly reliable GaN high electron mobility transistors (HEMTs) for high-power and high-efficiency amplifiers. First, we present the reliability mechanisms and progress on the previously reported GaN HEMTs. Next, we introduce our specific device structure of GaN HEMTs for improving reliability. An n-GaN cap and optimized buffer layer were used to suppress the trap-related phenomena, such as a current collapse. Gate edge oxidation is effective for reducing the gate leakage current. A Ta-based barrier metal was inserted between an ohmic electrode and interconnection metal for preventing increase in contact resistance. SiN of passivation film was optimized for reducing the current collapse of short-gatelength HEMTs.
Assessing the viability of cryopreserved coconut zygotic embryos by electrolytic conductivity and potassium leaching
Authors: Gomes-Copeland Kicia Karinne Pereira , Lédo Ana da Silva , Almeida Fabrício Tavares Cunha de , Miranda Roberta Pereira , Santos Izulmé Rita Imaculada
Published: October 2012

The objective of this work was to adapt the application of electrolytic conductivity and potassium leaching tests to assess the viability of cryopreserved embryos of 'Anão Verde do Brasil de Jiqui' (AVeJBr) coconut. The zygotic embryos were excised, sterilized and subjected to four cryoprotectant treatments combined with three incubation times (12, 16 and 20 hours), totaling 12 treatments. The pre-treatment of mature zygotic embryos of AVeJBr coconut using a cryoprotectant with 1.75 mol L-1 of sucrose + 15% glycerol for 12 and 16 hours promoted lower embryo humidity and increased viability in electrolytic conductivity and potassium leaching tests. Samples with ten embryos are sufficient for electrolytic conductivity analysis in cryopreserved or non-cryopreserved AVeJBr coconut zygotic embryos. The 4 to 8 hour imbibition period of the embryos is promising for the electrolytic conductivity analysis of non-cryopreserved mature zygotic embryos of AVeJBr coconut.
Épocas de semeadura e desempenho agronômico de cultivares de soja
Authors: Meotti Giovane Vanin , Benin Giovani , Silva Raphael Rossi , Beche Eduardo , Munaro Lucas Berger
Published: October 2012

O objetivo deste trabalho foi avaliar o efeito de épocas de semeadura no desempenho agronômico de cultivares de soja em São Domingos, SC, e indicar as cultivares mais estáveis e adaptadas a cada época. O experimento foi conduzido durante dois anos agrícolas (2008/2009 e 2009/2010), com seis cultivares e quatro épocas de semeadura (15/10, 15/11, 15/12 e 15/1), em delineamento experimental de blocos ao acaso, com três repetições e parcelas com área útil de 3,6 m². A metodologia AMMI (modelos de efeitos principais aditivos com interação multiplicativa) foi utilizada para avaliar o desempenho produtivo das cultivares, e a GGE (genótipo e interação genótipo x ambiente) para avaliar a adaptabilidade e a estabilidade das cultivares nas diferentes épocas de semeadura. Em ambos os anos agrícolas, as semeaduras em 15/10 e 15/11 maximizaram o número de vagens por planta, o número de grãos por vagem, a estatura das plantas, o número de ramos, a massa de mil sementes e, consequentemente, a produtividade de grãos. As cultivares de ciclo médio ou precoce com porte elevado são mais adequadas para semeaduras tardias.
Ganho de seleção no melhoramento genético intrapopulacional do maracujazeiro-amarelo
Authors: Krause Willian , Souza Regis Santos de , Neves Leonarda Grillo , Carvalho Maurecilne Lemes da Silva , Viana Alexandre Pio , Faleiro Fábio Gelape
Published: October 2012

O objetivo deste trabalho foi estimar o ganho de seleção associado a características agronômicas de importância no melhoramento intrapopulacional do maracujazeiro-amarelo. O experimento foi realizado em campo, no Município de Terra Nova do Norte, MT, com a avaliação de 111 famílias de irmãos completos (FIC) e seis cultivares comerciais, utilizadas como testemunhas. Utilizou-se o delineamento de blocos ao acaso, com três repetições e quatro plantas por parcela. Foram avaliadas as seguintes características: produtividade, comprimento, diâmetro e peso médio dos frutos, percentagem e peso de polpa, espessura de casca e teor de sólidos solúveis. Para verificar a existência de variabilidade genética entre os genótipos, estimaram-se os parâmetros genéticos da população com base na média das famílias. Os 30 genótipos com o menor valor da soma de postos, de acordo com o índice de seleção de Mulamba & Mock, foram selecionados para estimar os ganhos genéticos. Observaram-se altos valores médios para as características e parâmetros genéticos avaliados nas 26 FIC e nas quatro testemunhas selecionadas. O uso do índice de seleção proporciona ganhos genéticos positivos em produtividade, percentagem e peso de polpa, comprimento, diâmetro e peso de frutos, e espessura de casca.
Watermelon transformation with Zucchini yellow mosaic virus coat protein gene and comparison with parental cultivar
Authors: Çürük Sebahattin , Meşe Ebru
Published: October 2012

The objective of this work was to transfer Zucchini yellow mosaic virus coat protein (ZYMV-CP) and neomycin phosphotransferase II (NPT II) genes to the watermelon 'Crimson Sweet'(CS) genome, and to compare the transgenic progenies T1 and T2 with the nontransformed parental cultivar for morphological, pomological, growth and yield characteristics. The ZYMV-CP gene was transferred by Agrobacterium tumefaciens. The presence of the gene in transgenic T0, T1 and T2 plants was determined by polymerase chain reaction, and the results were confirmed by Southern blot. Two experiments were performed, one in the winter-spring and the other in the summer-autumn. In both experiments, the hypocotyl length of transgenic seedlings was significantly higher than that of nontransgenic parental ones. In the second experiment, the differences between transgenic and nontransgenic individuals were significant concerning fruit rind thickness, flesh firmness, fruit peduncle length, size of pistil scar, and a* values for fruit stripe or flesh color. Transferring ZYMV-CP gene to CS genome affected only a few characteristics from the 80 evaluated ones. The changes in rind thickness, flesh firmness and flesh color a* values are favorable, while the increase in the size of pistil scar is undesirable. The transgenic watermelon line having ZYMV-CP gene and the parental cultivar CS are very similar.
Eficiência simbiótica de estirpes de Cupriavidus necator tolerantes a zinco, cádmio, cobre e chumbo
Authors: Ferreira Paulo Ademar Avelar , Bomfeti Cleide Aparecida , Silva Júnior Romildo da , Soares Bruno Lima , Soares Cláudio Roberto Fonseca Sousa , Moreira Fatima Maria de Souza
Published: October 2012

O objetivo deste trabalho foi avaliar a tolerância de estirpes de Cupriavidus necator a zinco, cádmio, cobre e chumbo, além de determinar a eficiência simbiótica das estirpes mais tolerantes em associação a espécies leguminosas com potencial para revegetação. A tolerância foi testada em meio LB, suplementado com 2,5; 5,0; 7,5; 10; 12,5 e 15 mmol L-1 de ZnSO4.7H2O, CdSO4.8H2O, CuSO4.5H2O e PbCl2, respectivamente, em comparação ao controle sem adição de metal. Determinou-se a eficiência simbiótica das quatro estirpes de C. necator mais tolerantes aos metais avaliados (UFLA02-71, UFLA02-73, UFLA01-659 e UFLA01-663), as quais foram inoculadas nas espécies: Leucaena leucocephala, Enterolobium contortisiliquum, Acacia mangium, Mimosa caesalpiniifolia, M. pudica, M. pigra e M. acutistipula. Em vasos com solos, avaliaram-se L. leucocephala, M. pudica e M. caesalpiniifolia e as estirpes UFLA01-659 e UFLA02-71, selecionadas na avaliação de eficiência simbiótica. A estirpe UFLA02-71 proporcionou incrementos de matéria seca da parte aérea de 870% em M. caesalpiniifolia, enquanto que UFLA01-659 proporcionou 885% em M. pudica e 924% em L. leucocephala. As estirpes UFLA01-659 e UFLA02-71, além da alta tolerância a metais pesados, apresentaram eficiência em fixar nitrogênio, em simbiose com essas leguminosas, em solos com rizóbios nativos capazes de nodulá-las, e devem ser avaliadas quanto ao seu potencial de utilização em programas de recuperação de áreas degradadas.
Parâmetros sanguíneos, hepáticos e ruminais de ovinos alimentados com dietas com farelo de mamona destoxificado
Authors: Menezes Daniel Ribeiro , Costa Roberto Germano , Araújo Gherman Garcia Leal de , Pereira Luiz Gustavo Ribeiro , Oliveira Pablo Teixeira Leal de , Silva Aldrin Ederson Vila Nova , Voltolini Tadeu Vinhas , Moraes Salete Alves de
Published: October 2012

O objetivo deste trabalho foi avaliar os parâmetros sanguíneos, hepáticos e ruminais, bem como caracterizar e quantificar a população de protozoários ciliados, no rúmen de ovinos alimentados com dietas com farelo de mamona destoxificada (FM). Foram utilizados 32 ovinos, para a avaliação dos parâmetros sanguíneos e hepáticos, e quatro ovinos adultos fistulados no rúmen, para a avaliação dos parâmetros ruminais. A dieta controle foi composta por feno de capim-buffel, milho em grão moído, ureia e farelo de soja (FS). Nos tratamentos, o FS foi substituído parcialmente pelo FM a 15, 30 e 45% no concentrado. Não houve diferença, entre os tratamentos, quanto aos teores de ureia no soro, cuja média foi de 666,0 mg L-1. Não houve diferença entre as dietas quanto à glicose, ao aspartato aminotranferase e à alanina aminotransferase, que tiveram média de 690,3 mg L-1, 127,4 UI L-1 e 16,9 UI L-1, respectivamente. Os valores de nitrogênio amoniacal e pH apresentaram padrão linear crescente com a substituição do FS pelo FM. O gênero Entodinium foi o mais frequente em todos os tratamentos e obteve média geral de 76,4% do total de protozoários; o tratamento sem inclusão do FM obteve a maior percentagem deste gênero entre os tratamentos.Adieta com substituição de 45% do farelo de soja pelo de mamona destoxificado favorece o ambiente ruminal.
Multi-objective decision-aid tool for pavement management
Authors: Meneses Susana , Ferreira Adelino , Collop Andrew
Published: October 2012

This paper presents the development and implementation of a multi-objective decision-aid tool tested with data from Oliveira do Hospital's pavement management system. The pavement management system includes the following components: a road network database; a quality evaluation tool; a cost model; a pavement performance model; and a decision-aid tool. Nowadays, the pavement management system decision-aid tool uses a deterministic section-linked optimisation model with the objective of minimising the total expected discounted costs over the planning time-span while keeping the road pavements within given quality standards. The multi-objective decision-aid tool uses a multi-objective deterministic section-linked optimisation model with three different possible goals: minimisation of agency costs (maintenance and rehabilitation costs); minimisation of user costs; and maximisation of the residual value of pavements. This new approach allows pavement management systems to become interactive decision-aid tools capable of providing road administrators with answers to ‘what-if' questions in short times.
A general formulation for time-to-collision safety indicator
Authors: Saffarzadeh Mahmoud , Nadimi Navid , Naseralavi Saber , Mamdoohi Amir Reza
Published: October 2012

Time to collision is an important time-based safety indicator for detecting rear-end conflicts in traffic safety evaluations. A major weakness of the time to collision notion is the assumption of constant velocities during the course of an accident. In this paper we utilise equations of motion to develop a generalised formulation for time to collision by relaxing the assumption of constant velocity, constant acceleration and so on. This paper also illustrates how this concept can be applied to real-world data, and detailed data gathered in the NGSIM project are used. Then time to collision is calculated based on the assumption of constant speed, constant acceleration and linear acceleration for leading and following vehicles. Results indicate that in the third case (linear acceleration), the average duration of exposure to critical time to collision values is greater than the others. So, applying time to collision based on the assumption of linear acceleration in collision avoidance systems would decrease driver errors more than other cases.
Short, Multineedle Frequency Domain Reflectometry Sensor Suitable for Measuring Soil Water Content
Authors: Xu Jinghui , Ma Xiaoyi , Logsdon Sally D. , Horton Robert
Published: October 2012

Time domain reflectometry (TDR) is a well‐established electromagnetic technique used to measure soil water content. Time domain reflectometry sensors have been combined with heat pulse sensors to produce thermo‐TDR sensors. Thermo‐TDR sensors are restricted to having relatively short needles to accurately measure soil thermal properties. Short needle lengths, however, can limit the accuracy of the TDR measurement of soil water content. Frequency domain reflectometry (FDR) sensors are an alternative to TDR sensors that can provide an inexpensive measurement of soil water content. The objective of this study was to determine whether short FDR sensors can accurately measure soil water content. We designed and constructed a short FDR sensor. For four soil types across a range of water contents, temperatures, and salt contents, we measured soil dielectric spectra with the short FDR sensor. A vector network analyzer was used to obtain soil dielectric spectra in the 1‐MHz to 3‐GHz frequency range. The ideal frequency of a short FDR sensor is the frequency at which the permittivity is not altered by changing temperature or salt content. The 47‐ to 200‐MHz range was an ideal frequency range for measuring soil water content, and 70 MHz was the frequency least influenced by temperature and salt content. The short FDR sensor provided quick, continuous, stable, and cheap measurements of soil water content. Because of the promising performance of the short thermo‐FDR sensor in laboratory studies, sensors should be evaluated in future field studies.
Soil Organic Carbon Predictions by Airborne Imaging Spectroscopy: Comparing Cross‐Validation and Validation
Authors: Stevens Antoine , Miralles Isabel , van Wesemael Bas
Published: October 2012

Soil organic carbon (SOC) is considered to influence important processes affecting soil, air, and water quality. The management of this valuable resource could be assisted by remote sensing techniques able to provide high‐resolution spatial estimates of SOC. Such estimations are usually based on empirical regressions that are likely to have poor extrapolation abilities and hence it is important to properly estimate their accuracy in unsampled fields. Based on an imaging spectroscopy image acquired over the Luxembourg (c. 420 km2), several multivariate calibration models (partial least square [PLSR], penalized‐spline signal [PSR], and support vector machine [SVMR] regressions) were developed to predict SOC content of topsoil bare agricultural fields and compared. The performance of the models was evaluated by means of cross‐validation (k‐fold[KFO], leave‐one‐out [LOO], leave‐one‐group‐out [LOGO], and leave‐one‐field‐out [LOFO]) and these estimates were compared with model performance obtained by validation. The validation set excluded the fields used in the training set, to provide realistic measures of prediction error in unsampled fields. All cross‐validation techniques, except LOFO, strongly underestimate validation error. In large areas, training samples are often not a representative subset of the soil and spectral variation. Leave‐one‐field‐out cross‐validation, by repeatedly leaving samples belonging to one field out of the calibration, better simulates model error at unknown locations than other cross‐validation strategies. The root mean square error (RMSE) of the best models, obtained with a stringent validation procedure (leave‐fields‐out), was equal to 4.7 g C kg−1. This is higher than most of previous studies using imaging spectroscopy for SOC prediction, suggesting that measures of accuracy obtained by KFO, LOO, and LOGO are likely over‐optimistic in large areas. Finally, a SOC content map for the topsoil of croplands was produced that may assist soil monitoring and/or management efforts in this region in the future.
Residual Poultry Manure Nitrogen Supply to Corn the Second and Third Years after Application
Authors: Ruiz Diaz Dorivar A. , Sawyer John E. , Barker Daniel W.
Published: October 2012

Only a fraction of total N from poultry manure is plant available during the first year of application, and residual N may become available in subsequent years. The objective of this study was to evaluate the residual supply of plant‐available N from poultry manure to corn (Zea mays L.) in the second and third years after application. Two poultry manure sources were applied at two rates, targeting 84 and 168 kg total N ha−1. The fertilizer equivalence approach was used as reference to estimate residual fertilizer equivalent values. Soil samples were collected at 0 to 30 cm for NO3–N in early June in the second year. Grain yield and chlorophyll meter (CM) readings at the R1 growth stage were collected to evaluate corn response to fertilizer and residual manure N. Based on corn grain yield, 3 to 12% of poultry manure total N was plant available in the second year after application, and 4 to 20% based on CM readings. In the third year, plant‐available N ranged from 0 to 4% of total manure N. Soil NO3–N was not successful in detecting possible N supply from poultry manure in the second year after application. Suggestions for residual poultry manure N supply to corn should not exceed approximately 10% for the second year and 4% for the third year.
Preparation of single-walled carbon nanotubes/polyvinylchloride membrane and its antibacterial property
Authors: Zhao Fangbo , Qiu Feng , Zhang Xiaohui , Yu Shuili , Kim Han-Shin , Park Hee-Deung , Takizawa Satoshi , Wang Peng
Published: October 2012

Polyvinylchloride (PVC) ultrafiltration membranes were modified by blending with single-walled carbon nanotubes (SWCNTs) to improve the membranes’ antibacterial property. Both modified and control samples were characterized for pore structure, roughness, hydrophilicity, permeability and mechanical properties. The membranes’ antibacterial property was accessed with Escherichia coli as the model microbes by several methods. It was found that, after being blended with SWCNTs, the surface roughness of the modified membrane increased. Also, the surface hydrophilicity was improved. The membrane flux increased accordingly. But the membrane elongation decreased obviously with the SWCNTs addition. The modified membranes did not show the antibacterial property as expected in this research. There was no bacterial inhibition circle around the SWCNTs/PVC membrane coupons in the culture plates. There were no morphological differences of the cells on the control and the modified membranes. Hoechst 33342/propidium iodide stain test showed that there were more than 90% living bacterial cells which could grow on the SWCNTs/PVC membranes. This study suggests that the polymer wrapping may reduce the SWCNTs' antibacterial property greatly.
Effect of coagulation mechanisms on the fouling and ultrasonic cleaning of PTFE membrane
Authors: Wan Meng-Wei , Futalan Cybelle Morales , Chang Cheng-Hung , Kan Chi-Chuah
Published: October 2012

In this study, the effect of coagulation pretreatment on membrane fouling and ultrasonic cleaning efficiency was investigated using a dead-end polytetrafluoroethylene (PTFE) microfiltration system. The extent of membrane fouling was examined under different coagulation mechanisms such as charge neutralization (CN), electrostatic patch effect (EPE) and sweep flocculation (SW). Fouling through EPE mechanism provided the greatest flux decline and least permeate flux recovery over CN and SW. EPE produces more stable, smaller and more compact flocs while CN and SW have large, easily degraded and highly-branched structured flocs. The predominant fouling mechanism of EPE, CN and SW is pore blocking, a combination of pore blocking and cake formation, and cake formation, respectively. Better permeate flux recovery is observed with SW over CN and EPE, which implies formation of less dense and more porous cake deposits. The morphology of fouled membranes was examined using scanning electron microscopy (SEM).
A metabolic quotient for methanogenic Archaea
Authors: Munk B. , Bauer C. , Gronauer A. , Lebuhn M.
Published: October 2012

Biogas production from renewable resources is an alternative to generate energy and concomitantly save fossil fuels and mitigate greenhouse gas emissions. As methanogenesis is a major bottleneck in the biogas process, the determination of the specific activity of methanogenic Archaea can be a good indicator of the process state. A new parameter, the metabolic quotient (MQ), was developed to evaluate the specific activity of methanogens. A standard was created from mesophilic maize-fed fermenters to calculate the expected concentration of methanogens for a given methane productivity at stable process stages. The MQ, the ratio of the predicted to the actual concentration of methanogens, defines their metabolic activity. The MQ was able to indicate methanogenic cell stress metabolism and imminent process failure before conventional chemical parameters. As a further approach, the methanogenic activity was determined by quantification of mRNA transcripts in relation to the mcrA/mrtA-gene, coding for a key enzyme subunit of methanogenesis. The cDNA/DNA ratio reflected the specific actual process activity of the methanogens. As both methods are potent parameters for the early detection of process failure, biogas plant operators may avoid economical losses by their preventive application.
IWRM decision support with material flow analysis: consideration of urban system input
Authors: Terekhanova T. A. , Helm B. , Traenckner J. , Krebs P.
Published: October 2012

A review of material flow analysis (MFA) tools, comparison of case studies and analysis of approximately 20 MFA tools (static, semi-empirical models) are performed. The evaluation of the quantification procedures revealed several deficits in the approaches. The following principal complications for a reliable quantification of inputs from the urban water system are identified: (1) frequently insufficient data for urban system model validation (e.g. combined sewer overflow (CSO) discharges); (2) the necessity for additionally quantifying diffuse sources in order to verify modelling results at basin scale, where both input pathways occur, and (3) the contradictions arising when describing the highly dynamic urban system with the help of static MFA models. However, a wise selection of appropriate calculation procedures with regard to the concrete systems characteristics and available data can minimize the model deviations significantly. Criteria and suggestions for designing adapted quantification procedures are given.
Identifying biases in deterioration models using synthetic sewer data
Authors: Scheidegger A. , Maurer M.
Published: October 2012

The assessment and validation of sewer deterioration models is difficult because reliable data are missing. This makes it hard to find the most suitable model for a particular application. A network condition simulator (NetCoS) is used to generate synthetic sewer data for defined test scenarios. Thereby, the deterioration and replacement of pipes, the expansion of the sewer network, and classification errors are considered. Based on such synthetic data, deterioration models are calibrated and their results compared with the predefined scenario. While this approach is not capable of proving that a model performs correctly on a real application, it highlights the strengths and weaknesses of a model. The influence of condition classification errors and the age of the sewer system is investigated for two deterioration models. The results show, that classification errors can introduce substantial biases in the parameter estimation of the Markov model while in comparison the applied cohort model is fairly robust. Young sewer systems with fewer pipes in bad condition states on the other hand, have a very strong influence on the parameter uncertainties of the cohort model while the Markov model proved to be less sensitive.
Comparison of two polarity measurements of hydrophobic organic matter for the evaluation of water treatment processes: XAD resin and PRAM
Authors: Philibert Marc , Rosario-Ortiz Fernando , Suffet Mel
Published: October 2012

Dissolved organic matter (DOM) is a mixture of thousands of organic molecules wide-ranging in molecular weight, polarity and physicochemical properties. DOM is responsible for multiple water treatment issues such as trihalomethane (THM) formation potential and membrane fouling. Two methods of evaluating the polarity of DOM are being used for water treatment application: a serial XAD resin adsorption method at acid pH and the polarity rapid assessment method (PRAM) by parallel solid phase extraction (SPE) cartridges at natural pH. These two methods have been described by their authors as able to define a hydrophobic fraction though they do so by sorption onto different types of material at different pHs. The first part of this study compared the PRAM and XAD methods and showed that the hydrophobic fractions defined by the two approaches were not correlated. This result highlighted the difficulties in defining fractions as ‘hydrophobic material’. It appeared that the sorbents for XAD-8 (an acrylic polymer containing oxygen) at pH <3 and C-18 (a pure hydrocarbon polymer coating on silica particles) at neutral or pH <3 did not retain similar hydrophobic fractions. This hypothesis was verified by fluorescence spectroscopy of the effluent of the XAD-8 resin and PRAM C-18 SPE cartridge. Finally the study concentrated on the use of fluorescence and ultrafiltration methods in series with PRAM to gain more insight into the structure and characteristics of the hydrophobic DOM present in drinking water sources. This evaluation showed that the smaller molecular weight fraction of DOM (<1 kDa) had a higher percentage of hydrophobic character and that the fluorescence-defined aromatic protein fraction was the most hydrophilic.
Occurrence, fate, and fluxes of perfluorochemicals (PFCs) in an urban catchment: Marina Reservoir, Singapore
Authors: Nguyen Viet Tung , Gin Karina Yew-Hoong , Reinhard Martin , Liu Changhui
Published: October 2012

A study was carried out to characterize the occurrence, sources and sinks of perfluorochemicals (PFCs) in the Marina Catchment and Reservoir, Singapore. Salinity depth profiles indicated the reservoir was stratified with lower layers consisting of sea water (salinity ranging from 32 to 35 g L−1) and a brackish surface layer containing approximately 14–65% seawater. The PFC mixture detected in catchment waters contained perfluoroalkyl carboxylates (PFCAs), particularly perfluorooctanoate (PFOA), perfluorohexanoate (PFHpA), perfluorooctane sulfonate (PFOS) and PFC transformation products. PFC concentrations in storm runoff were generally higher than those in dry weather flow of canals and rivers. PFC concentration profiles measured during storm events indicated ‘first flush’ behavior, probably because storm water is leaching PFC compounds from non-point sources present in the catchment area. Storm runoff carries high concentrations of suspended solids (SS), which suggests that PFC transport is via SS. In Marina Bay, PFCs are deposited in the sediments along with the SS. In sediments, the total PFC concentration was 4,700 ng kg−1, approximately 200 times higher than in the bottom water layers. Total perfluoroalkyl sulfonates (PFSAs), particularly PFOS and 6:2 fluoro telomer sulfonate (6:2 FtS) were dominant PFCs in the sediments. PFC sorption by sediments varied with perfluorocarbon chain length, type of functional group and sediment characteristics. A first approximation analysis based on SS transport suggested that the annual PFC input into the reservoir was approximately 35 ± 12 kg y−1. Contributions of SS, dry weather flow of river/canals, and rainfall were approximately 70, 25 and 5%, respectively. This information will be useful for improving strategies to protect the reservoir from PFC contamination.
Sodium hydroxide pretreatment of ensiled sorghum forage and wheat straw to increase methane production
Authors: Sambusiti C. , Ficara E. , Rollini M. , Manzoni M. , Malpei F.
Published: October 2012

The aim of this study was to determine the effect of sodium hydroxide pretreatment on the chemical composition and the methane production of ensiled sorghum forage and wheat straw. NaOH pretreatment was conducted in closed bottles, at 40 °C for 24 h. Samples were soaked in a NaOH solution at different dosages (expressed in terms of total solids (TS) content) of 1 and 10% gNaOH/gTS, with a TS concentration of 160 gTS/L. At the highest NaOH dosage the reduction of cellulose, hemicelluloses and lignin was 31, 66 and 44%, and 13, 45 and 3% for sorghum and wheat straw, respectively. The concentration of soluble chemical oxygen demand (CODs) in the liquid phase after the pretreatment was also improved both for wheat straw and sorghum (up to 24 and 33%, respectively). Total sugars content increased up to five times at 10% gNaOH/gTS with respect to control samples, suggesting that NaOH pretreatment improves the hydrolysis of cellulose and hemicelluloses. The Biochemical Methane Potential (BMP) tests showed that the NaOH pretreatment favoured the anaerobic degradability of both substrates. At 1 and 10% NaOH dosages, the methane production increased from 14 to 31% for ensiled sorghum forage and from 17 to 47% for wheat straw. The first order kinetic constant increased up to 65% for sorghum and up to 163% for wheat straw.
Pilot-scale application of an online VFA sensor for monitoring and control of a manure digester
Authors: Boe K. , Angelidaki I.
Published: October 2012

A volatile fatty acids (VFA) sensor based on headspace chromatography was tested for online monitoring and control of a pilot-scale manure digester. The sensor showed satisfying results in terms of sensitivity and reliability for monitoring of the digester. The online VFA and biogas production data were used for automatic control of the digester based on feed flow manipulation. The control approach was based on optimization of biogas production while using VFA concentration as the alarm threshold. A rule-based supervisory system with a cascade controller was used to optimize the biogas production from the digester. The alarm state was set at 40 mM total VFA and 10 mM propionate concentration. The control algorithms could successfully maximize the biogas production without overloading the process. However, as the algorithm was based on a fixed biogas yield parameter and only used the biogas parameter for optimization, it could not distinguish between the decreases of biogas production from inhibition and from lower organic content in the substrate, which resulted in undesired decreasing of the control gas setpoint when the substrate was diluted. It was necessary to adjust the yield parameter in order to get this control approach to function properly, which is not suitable for the full-scale biogas plant where the organic content of waste streams can vary. An alternative approach could be a modified rule-based algorithm that includes VFA parameters to help distinguish between different process scenarios.
Investigation of Solution Chemistry Effects on Sorption Behavior of Cu(II) on ZSM‐5 Zeolite
Authors: Zhang Lipeng , Zhang Hui , Yu Xianjin
Published: October 2012

The sorption of Cu(II) from an aqueous solution using ZSM‐5 zeolite was investigated by batch technique under ambient conditions. Sorption was investigated as a function of pH, ionic strength, foreign ions, humic substances, and temperature. The results indicate that the sorption of Cu(II) on ZSM‐5 zeolite is strongly dependent on pH. Sorption is dependent on ionic strength at low pH, but independent of ionic strength at high pH values. The presence of humic/fluvic acid (HA/FA) enhances the sorption of Cu(II) on ZSM‐5 zeolite at low pH values, and reduces Cu(II) sorption at high pH values. Sorption isotherms were well simulated by the Langmuir model. Thermodynamic parameters (i.e., ΔH0, ΔS0 and ΔG0) for the sorption of Cu(II) were determined from temperature‐dependent sorption isotherms at 293.15, 313.15, and 333.15 K, respectively. Results indicate that the sorption process of Cu(II) on ZSM‐5 zeolite is spontaneous and endothermic.
Optimization of Circular Plate Separators with Cross Flow for Removal of Oil Droplets and Solid Particles
Authors: Ngu Hei , Wong Kien Kuok , Law Puong Ling
Published: October 2012

A circular gravity‐phase separator using coalescing medium with cross flow was developed to remove oil and suspended solids from wastewaters. Coalescence medium in the form of inclined plates promotes rising of oil droplets through coalescence and settling of solid particles through coagulation. It exhibits 22.67% higher removal of total suspended solids (TSS) compared to separators without coalescing medium. Moreover, it removed more than 70% of oil compared to conventional American Petroleum Institute separators, which exhibit an average of 33% oil removal. The flowrate required to attain an effluent oil concentration of 10 mg/L (Qo10) at different influent oil concentrations (Cio) can be represented by Qo10 × 10−5 = −0.0012Cio + 0.352. The flowrate required to attain an effluent TSS concentration of 50 mg/L (Qss50) at different influent TSS concentrations (Ciss) can be represented by Qss50 × 10−5 = 1.0 × 106 Ciss −2.9576. The smallest removable solid particle size was 4.87 µm.
Biosorption of Lead(II) in Aqueous Solution by Spent Mushroom Tricholoma lobayense
Authors: Dai Jiuzhou , Cen Feng , Ji Jinhu , Zhang Weiwei , Xu Heng
Published: October 2012

The biosorption of lead(II) ions in both simulated and real wastewater by spent mushroom Tricholoma lobayense, was studied in this work. The results show a biomass with a high potential for removing lead ions from wastewater. The optimum pH for the adsorption is 4, and the adsorption process is fast. The best sorbent mass of the biomaterial is 5 g/L with an initial lead(II) concentration of 1 mmol/L. The process follows the Langmuir isotherm model, and the biosorption capacity of lead ions reaches to 210 mg/g, which is higher than many biosorbents previously studied. The mechanism of biosorption may be mainly attributed to ion exchange. The FT‐IR study identifies the functional groups responsible for this process. A scanning electron microscope showed a significant change of the sorbent surface after the biosorption process. The energy dispersive elemental analysis also confirmed the adsorption of lead(II) ions.
Effects of Long Exposure to Low Temperatures on Nitrifying Biofilm and Biomass in Wastewater Treatment
Authors: Delatolla Robert , Tufenkji Nathalie , Comeau Yves , Gadbois Alain , Lamarre Daniel , Berk Dimitrios
Published: October 2012

Attached growth biological treatment systems are a promising solution to ammonia removal in cold‐temperature climates. Environmental scanning electron microscopy (ESEM) and confocal laser scanning microscopy in combination with fluorescent in situ hybridization (FISH) was used to investigate the effects of 4 months of exposure to 4 °C on nitrifying biofilm and biomass. These molecular and microscopic methods were modified to minimize loss of mass and distortion of in situ perspectives. Environmental scanning electron microscopy revealed that nitrifying biofilm did not exhibit significant changes in volume with exposure to 4 °C. Confocal laser scanning microscopy in combination with FISH showed that the number of ammonia‐oxidizing bacteria (AOB) cells present in the biofilm was statistically consistent during exposure to 4 °C. The RNA content of AOB cells remained sufficient for FISH enumeration. The number of nitrite‐oxidizing bacteria cells remained steady during exposure to 4 °C; however, the RNA content of the cells appeared to decrease with exposure to 4 °C, thereby preventing their enumeration using FISH.
Posterior Approach with Fibular Preservation for Tibiotalocalcaneal Arthrodesis with an Intramedullary Nail
Authors: Fetter Nicole Leigh , DeOrio James K.
Published: October 2012

Level of Evidence: V, Expert Opinion
Development of the Identification of Functional Ankle Instability (IdFAI)
Authors: Simon Janet , Donahue Matthew , Docherty Carrie
Published: October 2012

Background: Self-reported questionnaires are a common method used in identifying individuals with ankle instability. Recently a study illustrated the singular use of any of the most frequently utilized questionnaires failed to significantly predict ankle stability status. Therefore, the purpose of this article was to present information related to the development of the Identification of Functional Ankle Instability (IdFAI). Methods: Volunteers ( n = 278; 125 males, 153 females, 19.8 ± 1.4 years) completed the IdFAI on one occasion. An exploratory factor analysis was conducted with principal axis factoring as the extraction method with varimax rotation. Additionally, a discriminant function analysis was conducted to identify a discrimination score and to evaluate the accuracy of the questionnaire. Results: The factor analysis revealed: factor 1 (four questions) explained 53.7% of the variance, factor 2 (four questions) with an additional 17.4%, and factor 3 (two questions) an additional 6.3%. Overall, these factors accounted for 77.4% of the variance. There was a distinct discrimination score of 10.3 to identify people who have the minimally accepted criteria for FAI. Overall, the IdFAI has an accuracy of 89.6%. Conclusion: This investigation showed that the IdFAI was a feasible and appropriate way to identify individuals with FAI. Clinical Relevance: We suggest clinicians and researchers utilize the IdFAI to identify individuals with functional ankle instability since it is a short, simple, easy questionnaire to administer and take, and has been shown to have excellent accuracy.
Operative Technique of Two Parallel Compression Screws and Autologous Bone Graft for Ankle Arthrodesis after Failed Total Ankle Replacement
Authors: Jehan Shah , Hill Simon O.
Published: October 2012

Background: The management of failed total ankle replacement (TAR) depends on the primary indication, presence of infection, condition of adjacent joints, and available bone stock. In addition, the patient's expectations, age, and general health should also be taken into account. Methods: This article describes a technique of arthrodesis in failed TAR with two parallel screws inserted in opposite directions and autologous cancellous bone graft. Four patients were managed using this technique. The subtalar joint and both malleoli were preserved. Results: The average time for radiological union was 14.8 weeks. There were no hardware-related complications or infections. One patient developed subsequent subtalar arthritis and is waiting for subtalar joint fusion. Conclusion: The results from this small series of patients suggest that arthrodesis following failed total ankle replacement with two parallel screws and bone graft may be an effective technique.

Level of Evidence: IV, Retrospective Case Series
Dorsal Dislocation of the Great Toe in a Professional Football Player: Case Report
Authors: Sikka Robby Singh , Hunkele Thomas , Sugarman Eric , Myerson Mark S. , Fetzer Gary B. , Boyd Joel L.
Published: October 2012

Level of Evidence: V, Expert Opinion