bluuebunny/crossref_metadata_2025 huggingface dataset:
Phosphorus Movement and Speciation in a Sandy Soil Profile after Long‐Term Animal Manure Applications
Authors: Koopmans G. F. , Chardon W. J. , McDowell R. W.
Published: January 2007

Long‐term application of phosphorus (P) with animal manure in amounts exceeding removal with crops leads to buildup of P in soil and to increasing risk of P loss to surface water and eutrophication. In most manures, the majority of P is held within inorganic forms, but in soil leachates organic P forms often dominate. We investigated the mobility of both inorganic and organic P in profile samples from a noncalcareous sandy soil treated for 11 yr with excessive amounts of pig slurry, poultry manure, or poultry manure mixed with litter. Solution 31P nuclear magnetic resonance spectroscopy was used to characterize NaOH‐EDTA‐extractable forms of P, corresponding to 64 to 93% of the total P concentration in soil. Orthophosphate and orthophosphate monoesters were the main P forms detected in the NaOH‐EDTA extracts. A strong accumulation of orthophosphate monoesters was found in the upper layers of the manure‐treated soils. For orthophosphate, however, increased concentrations were found down to the 40‐ to 50‐cm soil layers, indicating a strong downward movement of this P form. This was ascribed to the strong retention of orthophosphate monoesters by the solid phase of the soil, preventing orthophosphate sorption and facilitating downward movement of orthophosphate. Alternatively, mineralization of organic P in the upper layers of the manure‐treated soils may have generated orthophosphate, which could have contributed to the downward movement of the latter. Leaching of inorganic P should thus be considered for the assessment and the future management of the long‐term risk of P loss from soils receiving large amounts of manure.
Vertical Distribution and Speciation of Trace Metals in Weathering Flotation Residues of a Zinc/Lead Sulfide Mine
Authors: Schuwirth Nele , Voegelin Andreas , Kretzschmar Ruben , Hofmann Thilo
Published: January 2007

Sulfide‐bearing mine tailings are a serious environmental problem around the world. In this study, the vertical distribution and speciation of Zn and Pb in the fine‐grained flotation residues of a former sulfide ore mine in Germany were investigated to assess the inorganic weathering processes that effect the environmental risk arising from this site. Total metal contents were determined by X‐ray fluorescence spectroscopy (XRF). Mobilizable fractions of Zn, Pb, Fe, and Mn were quantified by sequential chemical extractions (SCE). Furthermore, the speciation of Zn was analyzed by Zn K‐edge extended X‐ray absorption fine structure spectroscopy (EXAFS) to identify the residual Zn species. The variations in pH and inorganic C content show an acidification of the topsoil to pH 5.5. EXAFS results confirm that Zn is mainly bound in sphalerite in the subsoil and weathering reactions lead to a redistribution of Zn in the topsoil. A loss of 35% Zn and S from the topsoil compared with the parent material with 10 g kg−1 Zn and neutral pH has been observed. If acidification proceeds it will lead to a significant release of Zn, S, and Pb to the ground water. In contrast to Zn, Pb is enriched in the mobile fraction of the topsoil by more than a factor of two compared with the subsoil which contains a total of 2 g kg−1 Pb. Thus, the high bioavailability of Pb and the potential for Pb uptake by plants and animals currently represent the most severe threat for environmental health.
Field History and Dissipation of Atrazine and Metolachlor in Colorado
Authors: Shaner Dale L. , Henry W. Brien
Published: January 2007

Farmers in eastern Colorado have commented that atrazine does not provide the length of weed control that they expected in fields that have received multiple applications of the herbicide. Multiple laboratory studies suggest that atrazine dissipates more rapidly in soils with a history of atrazine use compared with soils that had not been treated with the herbicide and this could be related to the above observation. Field and laboratory studies were conducted to determine the rate of dissipation of atrazine and metolachlor in fields in Colorado. The published half‐lives of atrazine and metolachlor are 60 and 56 d, respectively. In the field studies, the half‐lives of atrazine and metolachlor in the top 15 cm of the soil ranged between 3.5 and 7.2 d and 17.9 and 18.8 d, respectively. In laboratory studies, the half‐life of atrazine varied from 1.4 to 19.8 d with the shortest half‐life occurring in soils which had been treated with atrazine for at least 5 yr. The longest half‐life was in a soil that had never received atrazine. The half‐life of metolachlor in these same soils varied from 10.6 to 28.2 d. There was no apparent relationship between the half‐life of metolachlor and the half‐life of atrazine in the laboratory studies. These results confirm farmers' observation of the shorter residual activity of atrazine in Colorado fields receiving atrazine over multiple years.
Biosensing Paraoxon in Simulated Environmental Samples by Immobilized Organophosphorus Hydrolase in Functionalized Mesoporous Silica
Authors: Lei Chenghong , Valenta Michelle M. , Saripalli K. Prasad , Ackerman Eric J.
Published: January 2007

There is a critical need for highly sensitive, cost‐effective sensors to conduct ecological analyses for environmental and homeland security‐related applications. Enzyme biosensors, which are currently gaining acceptance for environmental monitoring applications, need improvements to deliver faster measurements with stabilized sensing elements, e.g., enzymes. We report here on a method which significantly overcomes this difficulty, and demonstrate its application in a biosensor for aquatic environmental applications. A fast‐responding and stable biosensor was developed via immobilization of organophosphorus hydrolase (OPH) in functionalized mesoporous silica (FMS) with pore sizes in tens of nanometers. The OPH‐FMS composite was held on glassy carbon electrode by a dried Nafion gel and FMS protected OPH from Nafion‐resulted activity loss. The resulting enzyme biosensor, when integrated with an electrochemical instrument, responded rapidly to low paraoxon concentration and achieved steady‐state current in less than 10 s, with a detection limit of 4.0 × 10−7 M paraoxon. The biosensor was tested for detection of paraoxon in simulated environmental samples, under wide‐ranging physicochemical conditions. Results clearly indicate high recovery efficiencies in aqueous solutions (96 to 101%) at different pH, total organic carbon, total dissolved solids, and total suspended solids, and demonstrate the ability of the biosensor unit to continuously monitor paraoxon in aqueous conditions similar to those found in river and lake systems.
Interactive Fiction: ‘New Literacy’ Learning Opportunities for Children
Authors: Kozdras Deborah , Haunstetter Denise Marie , King James R.
Published: January 2007

Interactive fiction has great potential for use in schools, providing engaging and empowering opportunities for learning and literacy. Experiences with interactive fiction provide two key components lacking in contemporary storytelling mediums: autonomy (the ability to act and change on its own) and interactivity (or the ability to think and react intelligently to the user). This descriptive study analyzes a work of interactive fiction created specifically for this research, which illustrates essential traits of character-driven e-literature. The story is evaluated in terms of a set of principles, listed under a heading of empowered learners. Finally, the educational implications of using interactive fiction in an educational setting are discussed.
Teachers' Professional Development for the Technology-Enhanced Classroom in the School of Tomorrow
Authors: Hansson Henrik
Published: January 2007

This article discusses the following general questions: (1) what is the role of the teacher in the technology enhanced classroom; and (2) how are teachers prepared for the use of new technology in the classroom? The answers will differ among European countries due to, among other reasons, resources, national initiatives and available infrastructure. The overall goal of using technology in education also needs to be clarified. Is the driving force primarily of an economic nature to make education cheaper? Is the overall goal rather to improve the quality of learning? Is it about increasing student experiences? Is it about attracting more students? Does it have to do with increasing the prestige of teachers? Is it introduced in order to increase flexibility in time, place and organisation of learning? Or is it something else? This article is based on results from two European Union projects, E-watch and Schoolforesight, as well as innovative ideas and examples of teacher training and development. The European Union project E-watch investigated national policies for e-learning in Europe; the Schoolforesight project included among other activities an essay contest about students' visions of the future school. A study of teachers' visions of the future school was also conducted. No definite answers to the above questions are given, but a number of suggestions, opportunities and inspirational ideas are presented on how to organise the technology enhanced classroom and teachers' professional development.
Internet Use and Cognitive Development: A Theoretical Framework
Authors: Johnson Genevieve
Published: January 2007

The number of children and adolescents accessing the Internet as well as the amount of time online are steadily increasing. The most common online activities include playing video games, accessing web sites, and communicating via chat rooms, email, and instant messaging. A theoretical framework for understanding the effects of Internet use on cognitive development is presented. The proposed framework, based on the cognitive information processing model, the sociocultural perspective, the PASS cognitive processing model, and the neurological orientation, organises previous research in terms of the cognitive consequences of common online activities. From a cognitive-developmental perspective, the Internet is a cultural tool that influences cognitive processes and an environmental stimulus that contributes to the formation of specific cognitive architecture.
Distance Education in Brazil and in the United States: A Comparative View
Authors: Reifschneider Marina Becker
Published: January 2007

This article provides an overview of distance education in Brazil and compares it with that in the United States. It presents a brief historical perspective of private and public initiatives in Brazil and concentrates on present governmental projects and educational policies guiding distance education, with emphasis on higher education. Deficits of higher education are discussed and e-learning is presented as a partial solution to the problem of supply and demand of higher education in the country.
An Innovative Junior Faculty Online Development Programme
Authors: Villar Luis M. , Alegre Olga M.
Published: January 2007

This study examines whether two online courses offering educational support for junior faculty have a positive effect on their attitudes to learning and curriculum and teaching capacities (CTC). The data used in the analysis are from two 2005 online university training courses. The tasks the online courses assign to faculty, the resources they provide, the learning environment they create, and the conversations they provoke proved to be consequential in shaping faculty's attitudes. The results also indicate that junior faculty who participate in individual and collective online developing activities, such as constructing teaching episodes and communicating with other colleagues, are more likely to gain a better understanding of how to teach their scientific disciplines.
Demodex folliculorum in patients with rheumatoid arthritis
Authors: Ciftci Ihsan , Dundar Umit , Cetinkaya Zafer , Kulac Mustafa , Kiyildi Nilay , Turel Aycan , Evcik Deniz , Kavuncu Vural
Published: January 2007

The objective of this study was to investigate the incidence and density of Demodex folliculorum in the patients with rheumatoid arthritis (RA). Forty-one patients with RA and twenty-seven age and sex matched healthy controls were enrolled in this study. Disease Activity Score (DAS 28) was used for the assessment of disease activity. Out of 41 patients, 33 were females and 8 males. The mean disease duration was 10.9 ± 8.2 years. The mean DAS 28 was 3.8 ± 1.2. No statistically significant differences in the incidence and density of Demodex mites were found between patients with RA and controls. Although immunosuppression is thought to be a risk factor for the D. folliculorum infestation no such correlations could be found in the 41 immunosuppressed patients with RA, therefore, further studies with larger groups are needed.
A new case of de novo 11q duplication in a patient with normal development and intelligence and review of the literature
Authors: Zarate Yuri A. , Kogan Jillene M. , Schorry Elizabeth K. , Smolarek Teresa A. , Hopkin Robert J.
Published: January 2007

A new case of 11q interstitial duplication is reported in a patient with mild dysmorphic features but normal development. Chromosome analysis revealed a de novo 11q dup(11)(q14.1q21) on G banding and FISH studies. Additional molecular genetic studies revealed a similar but more distal duplication at the level of 11q21q23.1. Previous cases of isolated 11q duplication that overlapped with this case were associated with a wide variety of clinical findings and variable developmental disability. These cases all included additional material not duplicated in this patient. The current case represents the first de novo case of 11q duplication with normal development suggesting that the segment between 11q14.1 and 11q21 contains few genes that are dose sensitive. Review of other cases that have used conventional cytogenetic resolution studies suggests that the band 11q13.5 may contain genes contributing to the developmental disabilities in the cases previously reported with proximal 11q duplication. Differences between conventional cytogenetic techniques and newer molecular genetic studies are expected. These newer techniques will help refine prognosis and counseling for families in the future. © 2007 Wiley‐Liss, Inc.
Innentitelbild: Oligothiophene‐Based Catenanes: Synthesis and Electronic Properties of a Novel Conjugated Topological Structure (Angew. Chem. 3/2007)
Authors: Bäuerle Peter , Ammann Martin , Wilde Markus , Götz Günther , Mena‐Osteritz Elena , Rang Alexander , Schalley Christoph A.
Published: January 2007

Ein „π‐konjugiertes Catenan“ oder, besser gesagt, ein aus zwei ineinander verschlungenen konjugierten Makrocyclen gebildetes Catenan wurde durch eine doppelte Metalltemplatstrategie synthetisiert. Auffälliges Merkmal dieses Systems ist eine durch den Raum wirkende elektronische Wechselwirkung der Donoreinheiten (Oligothiophene, metallische Farbe) mit der Acceptorkomponente des anderen Rings (Phenanthrolin, blau). Einzelheiten finden Sie in der Zuschrift von P. Bäuerle et al. auf S. 367ff.
Inside Cover: A Molecular Solomon Link (Angew. Chem. Int. Ed. 1‐2/2007)
Authors: Pentecost Cari D. , Chichak Kelly S. , Peters Andrea J. , Cave Gareth W. V. , Cantrill Stuart J. , Stoddart J. Fraser
Published: January 2007

A molecular Solomon knot was isolated from a dynamic library of molecular knots by kinetically controlled crystallization. By incorporating mixed‐metal templates into the usual protocol employed in the synthesis of Borromean Rings, J. F. Stoddart and co‐workers obtained a molecular Solomon link as the only crystalline product under the reaction conditions described and were able to determine its X‐ray crystal structure, as they report in their Communication on page 218 ff.
The impact of time constraints on Internet and Web use
Authors: Slone Debra J.
Published: January 2007

This study examines the influence of time constraints on Internet and Web search goals and search behavior. Specifically, it looks at the searching behavior of public library Internet users who, previously limited to 30 minutes per Internet session, are given an unlimited amount of time for use. Interviews and observations were conducted with 34 participants searching on their own queries. Despite an increase in the time allowed for searching, most people spent less than 30 minutes on the Internet, carrying out tasks like paying bills, shopping, browsing, and making reservations. Those who took more than 30 minutes were looking for jobs or browsing. E‐mail use was universal. In this context, influences like time‐dependent and time‐independent tasks, use of search hubs to perform more efficient searches, and search diversity were recorded. Though there are a number of large and small studies of Internet and Web use, few of them focus on temporal influences. This study extends knowledge in this area of inquiry.
Citation data analysis on hydrogeology
Authors: Schwartz Frank , Fang Y.C.
Published: January 2007

This article explores the status of research in hydrogeology using data mining techniques. First we try to explain what citation analysis is and review some of the previous work on citation analysis. The main idea in this article is to address some common issues about citation numbers and the use of these data. To validate the use of citation numbers, we compare the citation patterns for Water Resources Research papers in the 1980s with those in the 1990s. The citation growths for highly cited authors from the 1980s are used to examine whether it is possible to predict the citation patterns for highly‐cited authors in the 1990s. If the citation data prove to be steady and stable, these numbers then can be used to explore the evolution of science in hydrogeology. The famous quotation, “If you are not the lead dog, the scenery never changes,” attributed to Lee Iacocca, points to the importance of an entrepreneurial spirit in all forms of endeavor. In the case of hydrogeological research, impact analysis makes it clear how important it is to be a pioneer. Statistical correlation coefficients are used to retrieve papers among a collection of 2,847 papers before and after 1991 sharing the same topics with 273 papers in 1991 in Water Resources Research. The numbers of papers before and after 1991 are then plotted against various levels of citations for papers in 1991 to compare the distributions of paper population before and after that year. The similarity metrics based on word counts can ensure that the “before” papers are like ancestors and “after” papers are descendants in the same type of research. This exercise gives us an idea of how many papers are populated before and after 1991 (1991 is chosen based on balanced numbers of papers before and after that year). In addition, the impact of papers is measured in terms of citation presented as “percentile,” a relative measure based on rankings in one year, in order to minimize the effect of time.
Effect of wall shear rate on biofilm deposition and grazing in drinking water flow chambers
Authors: Paris Tony , Skali‐Lami Salaheddine , Block Jean‐Claude
Published: January 2007

The effect of four‐wall shear rates (34.9, 74.8, 142.5, and 194.5 s−1) on bacterial deposition on glass slides in drinking water flow chambers was studied. Biofilm image acquisition was performed over a 50‐day period. Bacterial accumulation and surface coverage curves were obtained. Microscopic observations allowed us to obtain information about the dynamics and spatial distribution of the biofilm. During the first stage of biofilm formation (210–518 h), bacterial accumulation was a function of the wall shear rate: the higher the wall shear rate, the faster the bacterial deposition (1.1 and 1.9 × 104 bacterial cells · cm−2 for wall shear rates of 34.9 and 142.5 s−1, respectively). A new similarity relationship characteristic of a non‐dimensional time and function of the wall shear rate was proposed to describe initial bacterial deposition. After 50 days of exposure to drinking water, surface coverage was more or less identical under the entire wall shear rates (7.44 ± 0.9%), suggesting that biofilm bacterial density cannot be controlled using hydrodynamics. However, the spatial distribution of the biofilm was clearly different. Under low wall shear rate, aggregates were composed of bacterial cells able to “vibrate” independently on the surface, whereas, under a high wall shear rate, aggregates were more cohesive. Therefore, susceptibility to the hydraulic discontinuities occurring in drinking water system may not be similar. In all the flow chambers, significant decreases in bacterial biomass (up to 77%) were associated with the presence of amoebae. This grazing preferentially targeted small, isolated cells. Biotechnol. Bioeng. 2007; 97: 1550–1561. © 2007 Wiley Periodicals, Inc.
Prediction of mass transfer coefficients in non‐Newtonian fermentation media using first‐principles methods
Authors: Radl Stefan , Khinast Johannes G.
Published: January 2007

Bubble flows in non‐Newtonian fluids were analyzed using first‐principles methods with the aim to compute and predict mass transfer coefficients in such fermentation media. The method we used is a Direct Numerical Simulation (DNS) of the reactive multiphase flow with deformable boundaries and interfaces. With this method, we are able for the first time to calculate mass transfer coefficients in non‐Newtonian liquids of different rheologies without any experimental data. In the current article, shear‐thinning fluids are considered. However, the results provide the basis for further investigations, such as the study of viscoelastic fluids. Biotechnol. Bioeng. 2007; 97: 1329–1334. © 2007 Wiley Periodicals, Inc.
Sulfide oxidation at halo‐alkaline conditions in a fed‐batch bioreactor
Authors: van den Bosch Pim L.F. , van Beusekom Otto C. , Buisman Cees J.N. , Janssen Albert J.H.
Published: January 2007

A biotechnological process is described to remove hydrogen sulfide (H2S) from high‐pressure natural gas and sour gases produced in the petrochemical industry. The process operates at halo‐alkaline conditions and combines an aerobic sulfide‐oxidizing reactor with an anaerobic sulfate (SO) and thiosulfate (S2O) reducing reactor. The feasibility of biological H2S oxidation at pH around 10 and total sodium concentration of 2 mol L−1 was studied in gas‐lift bioreactors, using halo‐alkaliphilic sulfur‐oxidizing bacteria (HA‐SOB). Reactor operation at different oxygen to sulfide (O2:H2S) supply ratios resulted in a stable low redox potential that was directly related with the polysulfide (S) and total sulfide concentration in the bioreactor. Selectivity for SO formation decreased with increasing S and total sulfide concentrations. At total sulfide concentrations above 0.25 mmol L−1, selectivity for SO formation approached zero and the end products of H2S oxidation were elemental sulfur (S0) and S2O. Maximum selectivity for S0 formation (83.3±0.7%) during stable reactor operation was obtained at a molar O2:H2S supply ratio of 0.65. Under these conditions, intermediary S plays a major role in the process. Instead of dissolved sulfide (HS−), S seemed to be the most important electron donor for HA‐SOB under S0 producing conditions. In addition, abiotic oxidation of S was the main cause of undesirable formation of S2O. The observed biomass growth yield under SO producing conditions was 0.86 g N mol−1 H2S. When selectivity for SO formation was below 5%, almost no biomass growth was observed. Biotechnol. Bioeng. 2007; 97: 1053–1063. © 2007 Wiley Periodicals, Inc.
Encapsulation of proteins in biodegradable polymeric microparticles using electrospray in the Taylor cone‐jet mode
Authors: Xie Jingwei , Wang Chi‐Hwa
Published: January 2007

Solvent extraction (or evaporation from a W1/O/W2‐dispersion), coacervation, and spray drying methods are commonly employed to encapsulate protein drugs in polymeric microparticles for sustained delivery applications. To overcome the limitations of these methods, a novel electrospray method was developed to encapsulate a model protein drug—bovine serum albumin (BSA) in biodegradable polymeric microparticles and examine the feasibility of the process in not denaturing the protein. Microparticles of approximately 20 µm diameter with corrugated surfaces and smooth surfaces were observed by scanning electron microscope. Confocal laser scanning microscope images showed that BSA was distributed evenly in microparticles. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) was employed to investigate the protein integrity of BSA released from the polymer matrix after 38 days. No protein degradation was observed during the 38 days release. The secondary structure of released BSA was characterized by Fourier transform infrared (FTIR) and circular dichroism (CD), which suggested that the released BSA was almost identical to native BSA. The encapsulation efficiency could reach 76% by adjusting the amount of the additive Pluronic F127 and processing parameters. The release profile could be tailored by the fabrication process and the sustained release of BSA could endure for more than 1 month. More than 80% of the bioactivity of BSA (evaluated by BSA ELISA kit) could be maintained after releasing from polymer matrix. Findings of the present study demonstrate that this novel electrospray method is a promising approach to encapsulate bioactive materials such as proteins, enzymes, antibiotics, and DNA fragments in biodegradable polymeric particles. Biotechnol. Bioeng. 2007; 97: 1278–1290. © 2007 Wiley Periodicals, Inc.
Distributed state simulation of endogenous processes in biological wastewater treatment
Authors: Schuler Andrew J. , Jassby David
Published: January 2007

Distributed state‐type simulations (based on modeling of individual bacteria as they move through a reactor system) predicted a greater sensitivity of enhanced biological phosphorus removal (EBPR) performance to endogenous degradation than did conventional, “lumped”‐type simulations (based on average biomass compositions). Recent research has indicated that the variable hydraulic residence times experienced by individual microbial storage product accumulating bacteria in systems with completely mixed reactors tend to produce populations with diverse microbial storage product contents (distributed states). Endogenous degradation in EBPR systems is of particular interest because the polyphosphate accumulating organisms (PAOs) responsible for EBPR rely on the accumulation of three different storage products that may be endogenously degraded. Simulations indicated that as endogenous degradation rates of microbial storage products were increased, EBPR performance decreased more rapidly according to the distributed approach than according to the lumped approach. State profile analysis demonstrated that as these rates increased, the population fraction with depleted storage products also increased, and this tended to increase the error in calculated biokinetic rates by the lumped approach. Simulations based on recently reported endogenous rate coefficients also suggested large differences between distributed and lumped predictions of EBPR performance. These results demonstrated that endogenous decay processes may play a more important role in EBPR than predicted by the lumped approach. This suggests a need for further research to determine endogenous process rates, and for incorporation of this information to distributed‐type simulators, as this should lead to improved accuracy of EBPR simulations. Biotechnol. Bioeng. 2007; 97: 1087–1097. © 2007 Wiley Periodicals, Inc.
A simple numerical methodology for BFD problems using stream function vorticity formulation
Authors: Tzirtzilakis E. E.
Published: January 2007

The fundamental problem of biomagnetic fluid dynamics (BFD) in a 2D rectangular channel is numerically studied. The physical problem is described by a coupled, non‐linear system of partial differential equations, with appropriate boundary conditions. For the mathematical formulation, the stream function–vorticity formulation is used and the numerical solution is obtained by developing a pseudotransient numerical technique. A boundary condition for the vorticity is also constructed and grid stretching is used. The efficiency of the method is verified by comparison with other results documented in the literature. New results are also obtained for high values of the magnetic number which is the dominant factor for the determination of the flow field in biomagnetic fluid flow problems. Copyright © 2007 John Wiley & Sons, Ltd.
A simple way to introduce fibers into FEM models
Authors: Vanalli L. , Paccola R. R. , Coda H. B.
Published: January 2007

This communication proposes a simple way to introduce fibers into finite element modelling. This is a promising formulation to deal with fiber‐reinforced composites by the finite element method (FEM), as it allows the consideration of short or long fibers placed arbitrarily inside a continuum domain (matrix). The most important feature of the formulation is that no additional degree of freedom is introduced into the pre‐existent finite element numerical system to consider any distribution of fiber inclusions. In other words, the size of the system of equations used to solve a non‐reinforced medium is the same as the one used to solve the reinforced counterpart. Another important characteristic is the reduced work required by the user to introduce fibers, avoiding ‘rebar’ elements, node‐by‐node geometrical definitions or even complex mesh generation. An additional characteristic of the technique is the possibility of representing unbounded stresses at the end of fibers using a finite number of degrees of freedom. Further studies are required for non‐linear applications in which localization may occur. Along the text the linear formulation is presented and the bounded connection between fibers and continuum is considered. Four examples are presented, including non‐linear analysis, to validate and show the capabilities of the formulation. Copyright © 2007 John Wiley & Sons, Ltd.
Optimization of thermal environment during crystal growth of large‐sized Nd:YAG by Temperature Gradient Technique
Authors: Hongjun Li , Jun Xu , Liangbi Su , Benxue Jiang , Guangjun Zhao , Guoqing Zhou , Yongjun Dong
Published: January 2007

A finite‐element model is employed to analysis the thermal environments in Temperature Gradient Technique (TGT) furnace during the growth of large‐sized Nd:YAG crystal. The obtained results show that when the crucible is located at the lower position inside of the heater, a flatter solid‐liquid interface is established, which makes it easier to obtain the core‐free Nd:YAG crystal. Meanwhile, the lower crucible position can induce higher axial temperature gradient, which is beneficial to the release of latent heat. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of near stoichiometric LiNbO3 single crystal
Authors: Yao S. H. , Hu X. B. , Wang J. Y. , Liu H. , Gao L. , Cheng X. F. , Yin X. , Chen X. F.
Published: January 2007

A near stoichiometric LiNbO3 single crystal has been grown by the Czochralski method from a 58.5% Li melt hold in a large platinum crucible. High resolution X‐ray rocking curves of 30$ \bar 3 $0 and 0006 reflections indicated that the near stoichiometric LiNbO3 crystal possesses the high structural quality. Compared with the congruent LiNbO3, the near stoichiometric LiNbO3 possesses shorter ultraviolet absorption edge, thus higher Li concentration. The OH– infrared absorption band analyses showed that the Li concentration in the near stoichiometric LiNbO3 crystal is higher than that in the congruent LiNbO3 crystal. This result is in good agreement with that of the ultraviolet absorption edge. The electro‐optic (EO) coefficient γ22 of the near stoichiometric LiNbO3 crystal was measured to be 6.75 pm/V higher than that of congruent LiNbO3 crystal. It also proves the near stoichiometric LiNbO3 electro‐optic Q‐switched requires a low driving voltage and it is advantageous for the device performance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of gel grown calcium pyrophosphate tetrahydrate crystals
Authors: Parekh Bharat B. , Joshi Mihir J.
Published: January 2007

Formation of calcium pyrophosphate dihydrate (CPPD) crystals in soft tissues such as cartilage, meniscus and synovial tissues lead afflictions. The appearance of these crystals in the synovial fluid give rise to acute arthritis attack, which is known as pseudo‐gout. The growth of calcium pyrophosphate crystals in gel medium can mimic the growth in a body. In the present study, calcium pyrophosphate tetrahydrate (CPPT) crystals are grown by a single diffusion gel growth technique and characterized by powder XRD, FT‐IR spectroscopy, TGA, kinetic and thermodynamic studies of dehydration and dielectric studies. Monoclinic crystals structure, presence of P‐O bonds and four water molecules are confirmed from powder XRD, FT‐IR and TGA studies, respectively. The dielectric investigation suggests the reduction in dielectric constant with increase in frequency. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of TGS crystals using uniaxially solution‐crystallization method of Sankaranarayanan‐Ramasamy
Authors: Balamurugan N. , Lenin M. , Bhagavannarayana G. , Ramasamy P.
Published: January 2007

The recently discovered crystal growth method called uniaxially solution‐crystallization method of Sankaranarayanan–Ramasamy (SR) is modified in some aspects and used for growth of triglycine sulphate (TGS) crystals. The modification leads to the simplicity, reduction of cost and avoided the temperature fluctuations. The 〈010〉 direction of TGS is very important and used for fabrication of infrared detectors. Using this method, the 〈001〉, 〈010〉 directional crystals of TGS were successfully grown in a glass crystallizer. The grown crystal was characterized by HRXRD, UV‐Visible and dielectric studies. The results prove the suitability of the modified SR method for oriented TGS crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spectroscopic and thermal investigations of poly(vinylidene fluoride) films composites with LaNi3Co2
Authors: Elashmawi I. S. , Elsheshtawi N. A. , Abdelkader H. I. , Hakeem N. A.
Published: January 2007

Poly(vinylidene fluoride) (PVDF) and LaNi3Co2 were composites in various combinations by using melting technique. Morphological and physical properties of both the surface and interface of poly(vinylidene fluoride)/ LaNi3Co2 composite films have been investigated. FTIR and XRD diffraction analysis evidenced the increase of α, β and γ‐ PVDF crystalline phases. The bands at 888 and 1414 cm‐1 were assigned to γ‐phase of PVDF. Maximum value of the relative amount of β‐phase was observed at 35 and 60% FL. This result was confirmed by X‐ray diffraction (XRD) and differential scanning calorimetry (DSC) analysis. Maximum value of degree of crystallinity was observed at 15% Filling level (FL). Morphology of SEM consists of two different size rings and spherulites. DSC was used to identify the melting temperature, the order of reaction and the activation energy of melting. A sharp endothermic peak at Tm ≈ 444 K due to melting and T2 ≈ 360 K due to α‐relaxation/transition. Maximum values of magnetoresistance (MR) observed from range (243 to 238K) are due to reorientation of dipoles in a process associated with the glass transition temperature of PVDF. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Single crystal EPR study of Mn(II) doped MgRb2(SO4)2·6H2O: A case of interstitial site
Authors: Sankar B. , Natarajan B. , Mithira S. , Anandhalakshmi H. , Rao P. Sambasiva
Published: January 2007

Single crystal electron paramagnetic resonance studies on magnesium rubidium sulphate hexahydrate doped with Mn(II) impurity, in the form of 0.1% of manganous chloride, are carried out at room temperature. The angular variation spectra of the crystal in the three orthogonal planes show that the paramagnetic impurity Mn(II) has entered the host lattice interstitially. The spin Hamiltonian parameters calculated are: gxx = 1.974, gyy = 1.928, gzz = 1.980; Axx = 9.28, Ayy = 8.58, Azz = 9.87 mT and Dxx = ‐18.71, Dyy = ‐5.59, Dzz = 24.30 mT. The room temperature and liquid nitrogen temperature study for polycrystalline sample indicate no phase transition. The percentage covalency of Mn–O bond has been estimated to be 11. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies on the structural, thermal and optical behaviour of solution grown organic NLO material: 8‐hydroxyquinoline
Authors: Vijayan N. , Bhagavannarayana G. , Maurya K. K. , Pal S. , Datta S. N. , Gopalakrishnan R. , Ramasamy P.
Published: January 2007

Single crystal of 8‐hydroxyquinoline (8HQ) having chemical formula C9H7NO, an organic nonlinear optical (NLO) material has been successfully grown by slow evaporation solution growth technique at room temperature. The crystal system has been confirmed from the powder X‐ray diffraction (PXRD) analysis. The crystalline perfection was evaluated by high resolution X‐ray diffractometry (HRXRD). From this analysis we found that the quality of the crystal is quite good. However, a very low angle (tilt angle 14 arc sec) boundary was observed which might be due to entrapping of solvent molecules in the crystal during growth. Its optical behavior has been examined by UV‐Vis. analysis, which shows the absence of absorbance between the wavelengths ranging from 400 to 1200 nm. From the thermal analysis it was observed that the material exhibits single sharp weight loss starting at 113°C without any degradation. The laser damage threshold was measured at single shot mode and the SHG behavior has been tested using Nd:YAG laser as a source. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polymeric metal‐organic octupolar NLO materials: lithium(I) and sodium(I) 3,5‐dinitrobenzoates
Authors: Yang Guang , Weng Ng Seik
Published: January 2007

Lithium 3,5‐dinitrobenzoate (Li(dnb)) exhibits a 1D propeller chain structure of D 3 point symmetry and the chains are trigonally assembled in the crystal under the chiral space group P 3121. Sodium 3,5‐dinitrobenzoate (Na(dnb)) also crystallizes in space group P 3121 and exhibits a 3D structure. The structure of Na(dnb) could be regarded to be similar to that of Li(dnb) if the weaker Na‐O(nitro) bonds were to be ignored. These two compounds represent rare examples of octupoles arranged in an octupolar environment and show modest powder SHG effects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
fgf1 is required for normal differentiation of erythrocytes in zebrafish primitive hematopoiesis
Authors: Songhet Pascal , Adzic Dejan , Reibe Saskia , Rohr Klaus B.
Published: January 2007

Hematopoiesis in vertebrate development involves an embryonic, primitive wave and a later, definitive wave in which embryonic blood cells are replaced with adult blood cells. We here show that zebrafish fgf1 is involved in vivo in primitive hematopoiesis. Fibroblast growth factor‐1 (FGF1) morpholino knockdown leads to abnormal accumulation of blood cells in the posterior intermediate cell mass at 32 hr postfertilization. Expression of the erythroid markers gata1 and ika, normally diminishing in differentiating erythrocytes at this stage, is maintained at abnormally high levels in primitive blood cells. The onset of erythrocyte differentiation as assessed by o‐dianisidine staining is severely delayed. Most fgf1 morphants later recover to wild‐type appearance, and primitive erythrocytes eventually differentiate. Zebrafish fgf1 is syntenic to human FGF1, which maps to a critically deleted region in human del(5q) syndrome posing an increased risk of leukemia to patients. As its knockdown in zebrafish changes expression of gata1, a gene involved in hematopoietic stem cell decisions, FGF1 should be considered to play a role in the pathogenesis of del(5q) syndrome. Developmental Dynamics 236:633–643, 2007. © 2007 Wiley‐Liss, Inc.
Activation of dendritic cells by the Gal‐lectin of Entamoeba histolytica drives Th1 responses in vitro and in vivo
Authors: Ivory Catherine P. A. , Chadee Kris
Published: January 2007

Amebiasis is a human disease caused by the protozoan intestinal parasite Entamoeba histolytica. Vaccine development has focused on the parasite's surface galactose‐N‐acetyl‐d‐galactosamine inhibitable lectin (Gal‐lectin) as a protective antigen. The Gal‐lectin is immunogenic and has been shown to induce Th1 cytokines in vitro and in vivo. The immunological basis of the protective immune response elicited by the Gal‐lectin is unknown. In this study, we investigated the response of BALB/c bone marrow‐derived DC to E. histolytica Gal‐lectin. Incubation of immature DC with Gal‐lectin resulted in activation and maturation after 24 h. FACS analysis demonstrated an up‐regulation of DC maturation markers CD80, CD86, CD40 and MHC class II upon exposure to Gal‐lectin. The Gal‐lectin also induced DC production of IL‐12, indicating a Th1 response. Gal‐lectin‐activated DC were able to stimulate T cell proliferation in an allogeneic mixed leukocyte reaction and adoptive transfer of Gal‐lectin‐treated DC into naïve mice resulted in IFN‐γ‐producing Gal‐lectin‐sensitized T cells. The activation of DC by Gal‐lectin was mediated by MAPK and NF‐κB. These findings indicate that E. histolytica Gal‐lectin is a potent vaccine antigen capable of directly initiating DC maturation and activation characterized by Th1 cytokine production.
Formation of a Ruthenium μ‐Carbide Complex with Acetylene as the Carbon Source (Eur. J. Inorg. Chem. 3/2007)
Authors: Solari Euro , Antonijevic Sasa , Gauthier Sébastien , Scopelliti Rosario , Severin Kay
Published: January 2007

The cover picture shows the structure of a novel ruthenium complex with a μ‐carbide ligand. This complex was obtained in an unexpected reaction from [(p‐cymene)Ru(μ‐Cl)3RuCl(C2H4)(PCy3)] and acetylene. The solid‐state 13C NMR spectrum of a μ‐carbide complex obtained from fully 13C‐labeled acetylene shows a strong peak at δ = 430.5 ppm. This confirms that acetylene was the source of the μ‐carbide ligand and that the complex was formed by cleavage of the carbon triple bond. More details about this unusual reaction are described in the Short Communication by K. Severin et al. on p. 367 ff.
Feedbacks between erosion and sediment transport in experimental bedrock channels
Authors: Johnson Joel P. , Whipple Kelin X.
Published: January 2007

Natural bedrock rivers flow in self‐formed channels and form diverse erosional morphologies. The parameters that collectively define channel morphology (e.g. width, slope, bed roughness, bedrock exposure, sediment size distribution) all influence river incision rates and dynamically adjust in poorly understood ways to imposed fluid and sediment fluxes. To explore the mechanics of river incision, we conducted laboratory experiments in which the complexities of natural bedrock channels were reduced to a homogenous brittle substrate (sand and cement), a single sediment size primarily transported as bedload, a single erosion mechanism (abrasion) and sediment‐starved transport conditions. We find that patterns of erosion both create and are sensitive functions of the evolving bed topography because of feedbacks between the turbulent flow field, sediment transport and bottom roughness. Abrasion only occurs where sediment impacts the bed, and so positive feedback occurs between the sediment preferentially drawn to topographic lows by gravity and the further erosion of these lows. However, the spatial focusing of erosion results in tortuous flow paths and erosional forms (inner channels, scoops, potholes), which dissipate flow energy. This energy dissipation is a negative feedback that reduces sediment transport capacity, inhibiting further incision and ultimately leading to channel morphologies adjusted to just transport the imposed sediment load. Copyright © 2007 John Wiley & Sons, Ltd.
Geoarchaeology of the Kostenki–Borshchevo sites, Don River Valley, Russia
Authors: Holliday Vance T. , Hoffecker John F. , Goldberg Paul , Macphail Richard I. , Forman Steven L. , Anikovich Mikhail , Sinitsyn Andrei
Published: January 2007

The Kostenki–Borshchevo localities include 26 Upper Paleolithic sites on the first and second terraces along the west bank of the Don River, near Voronezh on the central East European Plain. Geoarchaeological research from 2001 through 2004 focused on sites Kostenki 1, 12, and 14, with additional work at Kostenki 11 and 16, and Borshchevo 5. The strata are grouped into three units (bottom up): Unit 1, > 50 ka, consists of coarse alluvium (representing upper terrace 2 deposits) and colluvium, overlain by fine‐grained sediments. Unit 2 includes archaeological horizons sealed within two sets of thin lenses of silt, carbonate, chalk fragments, and organic‐rich soils (termed the Lower Humic Bed and Upper Humic Bed) dating 50–30 ka. Separating the humic beds is a volcanic ash lens identified as the Campanian Ignimbrite Y5 tephra, dated elsewhere by Ar/Ar to ca. 40 ka. The humic beds appear to result from the complex interplay of soil formation, spring deposition, slope action, and other processes. Several horizons buried in the lower part of Unit 2 contain Upper Paleolithic assemblages. The springs and seeps, which are still present in the area today, emanated from the bedrock valley wall. Their presence may account for the unusually high concentration of Upper Paleolithic sites in this part of the central East European Plain. Unit 3, < 30 ka, contains redeposited loess with a buried soil (Gmelin Soil) overlain by a primary full‐glacial loess with an associated Chernozem (Mollisol), forming the surface of the second terrace. © 2007 Wiley Periodicals, Inc.
The lower paleolithic landscape of 'Ayoun Qedim, al‐Jafr Basin, Jordan
Authors: Rech Jason A. , Quintero Leslie A. , Wilke Philip J. , Winer Emily R.
Published: January 2007

The 'Ayoun Qedim locality includes seven deflated Acheulian sites within and around a limestone box canyon, Juwit el Ghuweir, in the northern al‐Jafr Basin, Jordan. Survey of these sites identified dense scatters of Acheulian bifaces ( _ 1650) along with debris, cores, and reduction material from their production and maintenance. Although there is a clear Levallois component in the assemblages, reflecting a Late Acheulian occupation, strictly Middle and Upper Paleolithic sites are uncommon in this locality. Analysis of the geology and geomorphology of the northern al‐Jafr Basin indicates the area is strongly influenced by shallow subsurface groundwater flow and discharge, and Juwit el Ghuweir displays classic features of a canyon formed by groundwater seepage and sapping, except for the lack of a perennial spring within the modern canyon. The authors suggest that the extreme density of Lower Paleolithic material at 'Ayoun Qedim is associated with perennial groundwater discharge at Juwit el Ghuweir during the Middle Pleistocene and that the dearth of later Paleolithic material is attributable to the cessation of perennial spring discharge. The cause of the spring's cessation is unknown, but may have been related to local geomorphic factors, such as head migration of adjacent streams, or to more regional geomorphic factors, such as the lowering of theregional water table in the area of al‐Jafr Basin. © 2007 Wiley Periodicals, Inc.
Book Reviews
Authors: Feathers James K.
Published: January 2007

Quaternary Dating Methods. Mike Walker, 2005, John Wiley & Sons, Ltd., Chichester, England, xvii + 286 pp. $55.00 (hardcover)