bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of pH on metal speciation and resulting metal uptake and toxicity for earthworms
Authors: Spurgeon David J. , Lofts Stephen , Hankard Peter K. , Toal Mark , McLellan Donna , Fishwick Samantha , Svendsen Claus
Published: February 2006

In the present study, relationships between changes in the solubility and speciation of metals in contaminated soils under different pH regimes and their toxicity to earthworms were investigated. Earthworms (Lumbricus rubellus) were exposed in a laboratory bioassay to metalliferous soils under three pH regimes: Unamended pH, pH lowered by one unit (pH — 1), and pH increased by one unit (pH +1). In each soil, total (hot nitric acid-extractable) and 0.01 M CaCl2–extractable metal concentrations were measured and soil pore-water chemistry analyzed to allow metal speciation to be modeled using the Windermere Humic Aqueous Model. Earthworm metal accumulation was determined and toxicity assessed by measuring survival and reproduction and at the molecular level by recording expression of the gene encoding metallothionein-2 (MT-2) using quantitative reverse transcriptase-polymerase chain reaction. Both metal solubility and speciation were found to be highly pH dependent. Metal accumulation in earthworms was influenced by soil concentration and, in some cases (e.g., Cd), by pH. Reproduction was affected (reduced up to 90%) by soil metal level, pH, and their interaction. Relationships between analyzed and calculated Zn concentrations and toxicity and between analyzed and calculated Cd concentrations and tissue accumulation and MT-2 expression were compared by fitting dose-response models and assessing the fit of the data. This analysis indicated that values based on a pH-adjusted free ion concentration best explained toxicity (r2 = 0.82) and accumulation (r2 = 0.54). Expression of MT-2 was, however, poorly correlated (p > 0.05) with all analyzed and modeled soil metal concentrations.
Kinetics of metal fixation in soils: Measurement and modeling by isotopic dilution
Authors: Crout Neil M. J. , Tye Andy M. , Zhang Hao , McGrath Steve P. , Young Scott D.
Published: February 2006

The bioavailability of metal contaminants in soils varies widely, depending on soil characteristics and the source of the contaminant. As a consequence, site-specific risk assessment requires accurate prediction of the bioavailable (or labile) fraction of soil metal. Moreover, metals in soil are subject to time-dependent processes, which affect their bioavailability and thereby complicate the prediction of future risk. The aim of the present study was to describe the development of simple, readily applicable models for the time-dependent changes in lability of Cd and Zn in soils. We present data showing the time-dependent behavior of radiolabile and soil solution concentrations of Cd and Zn during an incubation study over a period of 813 d in 23 diverse soils. The data are used to parameterize candidate models of metal fixation in soils designed to be readily applicable and therefore relevant to risk assessment. We conclude that the final extent of metal fixation increases with pH and generally is greater for Zn than for Cd; however, the rate of fixation is independent of pH and equivalent to a half-time to equilibrium of 29 and 89 d for Cd and Zn, respectively. It is possible that longer-term processes occur, especially for Zn, but these could not be detected in the present study.
Biological significance of metals partitioned to subcellular fractions within earthworms (Aporrectodea caliginosa)
Authors: Vijver Martina G. , van Gestel Cornelis A. M. , van Straalen Nico M. , Lanno Roman P. , Peijnenburg Willie J. G. M.
Published: February 2006

Metal ions in excess of metabolic requirements are potentially toxic and must be removed from the vicinity of important biological molecules to protect organisms from adverse effects. Correspondingly, metals are sequestrated in various forms, defining the accumulation pattern and the magnitude of steady-state levels reached. To investigate the subcellular fractions over which Ca, Mg, Fe, Cu, Zn, Cd, Pb, Ni, and As are distributed, earthworms (Aporrectodea caliginosa) collected from the field were analyzed by isolating metal-rich granules and tissue fragments from intracellular microsomal and cytosolic fractions (i.e., heat-stable proteins and heat-denatured proteins). The fractions showed metal-specific binding capacity. Cadmium was mainly retrieved from the protein fractions. Copper was equally distributed over the protein fraction and the fraction comprising tissue fragments, cell membranes, and intact cells. Zinc, Ca, Mg, and As were mainly found in this fraction as well. Lead, Fe, and Ni were mainly isolated from the granular fraction. To study accumulation kinetics in the different fractions, three experiments were conducted in which earthworms were exposed to metal-spiked soil and a soil contaminated by anthropogenic inputs and, indigenous earthworms were exposed to field soils. Although kinetics showed variation, linear uptake and steady-state types of accumulation patterns could be understood according to subcellular compartmentalization. For risk assessment purposes, subcellular distribution of metals might allow for a more precise estimate of effects than total body burden. Identification of subcellular partitioning appears useful in determining the biological significance of steady-state levels reached in animals.
Forage Chicory and Plantain Nutritive Value of Herbage at Variable Grazing Frequencies and Intensities
Authors: Labreveux María , Sanderson Matt A. , Hall Marvin H.
Published: February 2006

Cultivars of forage chicory (Cichorium intybus L.) and plantain (Plantago lanceolata L.) grown in the northeastern USA have acceptable seasonal productivity; however, their reproductive habit could limit herbage nutritive value. The nutritive value of chicory and plantain cultivars was compared and examined under the effect of variable frequency and intensity of grazing. The cultivars were compared with ‘Pennlate’ orchardgrass (Dactylis glomerata L.), a productive grass during the summer, in two grazing experiments in 3 yr. Pre‐grazing herbage samples were analyzed and compared for crude protein (CP), neutral detergent fiber (NDF), and in vitro true digestibility of dry matter (IVTD). In both experiments, the average CP of entries was 180 to 200 g kg−1, similar to orchardgrass. The NDF of forbs, which ranged from 300 to 400 g kg−1, was 200 g kg−1 lower than orchardgrass. The IVTD of chicory cultivars averaged 850 to 950 g kg−1. In Exp. 1, ‘Forage Feast’ and ‘Puna’ chicory had the greatest IVTD (5% greater than orchardgrass: average 911 vs. 867 g kg−1, respectively; P < 0.05). Lancelot plantain had the lowest IVTD in both experiments. Grazing management (frequency of grazing) affected nutritive value in Exp. 1 but not in Exp. 2. Although herbage composition in Exp. 2 varied, continuous reproductive development did not affect nutritive value. Managing Puna chicory and Lancelot plantain using a canopy‐height based grazing system to maximize yield and persistence does not compromise nutritive value. Puna chicory could be a good complement to Pennlate orchardgrass in grass‐based feeding systems.
Spatial Variability of In‐Season Nitrogen Uptake by Corn Across a Variable Landscape as Affected by Management
Authors: Dharmakeerthi R. S. , Kay B. D. , Beauchamp E. G.
Published: February 2006

An understanding of the spatial and temporal variability of N uptake at a landscape scale is required to implement site‐specific N management. We determined the spatial variation of in‐season N uptake and N nutritional status of corn (Zea maysL.) in a variable landscape in southern Ontario from 1997 to 2001 under three management conditions involving corn under no‐tillage or conventional tillage using barley (Hordeum vulgareL.) or barley under‐seeded with red clover (Trifolium pratenseL.) as the preceding crop and with or without fertilizer N. The aerial dry matter content (DM) of corn and N concentrations in the DM (Ni) were determined at 2‐wk intervals. Organic C (OC) content (0–0.3 m) was used as the landscape‐based variable to account for the spatial variability of N uptake. Fertilizer N addition, legume incorporation, and tillage had significant positive effects on N uptake, but the magnitude of these effects varied within and among growing seasons. Nitrogen uptake increased with OC content in a quadratic relationship, reaching a maximum at OC content of about 26 g kg−1. The N nutritional status in the DM, estimated using previously established critical dilution curves, also increased with OC content. However, the nutritional status decreased as the growing season progressed under all management treatments; this decrease was largest at the smallest OC contents. These trends suggest that measurements of plant N early in the season cannot be used in site‐specific N management to accurately identify areas of adequate or excess N later in the growing season.
Influence of Sperm Pretreatment on the Efficiency of Intracytoplasmic Sperm Injection in Pigs
Authors: García‐Roselló Empar , Matás Carmen , Cánovas Sebastián , Moreira Pedro N. , Gadea Joaquín , Coy Pilar
Published: February 2006

ABSTRACT: The purpose of this study was to determine the influence of sperm pretreatment on the efficiency of intracytoplasmic sperm injection (ICSI) in pigs. This was done by examining the effect of 1) the conservation method (fresh vs frozen); 2) the sperm treatment preinjection (resuspension in Dulbecco phosphate‐buffered saline (DPBS) vs selection by a Percoll gradient); and 3) the acrosomal and live or dead status of the spermatozoa (by incubation with or without calcium ionophore, 1 μM and 5 μM). In vitro matured porcine oocytes were injected with treated spermatozoa according to each experiment. All the experiments were done with non—artificially activated oocytes. The percentages of activation and cleavage were higher (68% vs 43% and 63% vs 43%, respectively, P < .05) in oocytes injected with fresh vs frozen spermatozoa. The DPBS treatment allowed higher cleavage proportions than the Percoll treatment (P < .05). Moreover, a boar effect was observed in the percentage of developing blastocysts. None of the studied parameters was affected by the acrosomal or the live or dead status of the spermatozoa injected. In conclusion, the use of fresh semen is recommended for porcine ICSI, as well as careful selection of the boar; Percoll treatment is only recommended for poor‐quality samples or for removing toxic agents, and no exogenous form of activation or induction of the acrosome reaction is necessary for porcine oocytes to develop a male pronucleus and cleave up to the 2‐cell stage after ICSI, although experimental conditions to reach the blastocyst stage need to be investigated further.
The Precision and Accuracy of Six Different Methods to Determine Sperm Concentration
Authors: Prathalingam Nilendran S. , Holt William W. , Revell Stuart G. , Jones Sian , Watson Paul F.
Published: February 2006

ABSTRACT: The development of new technologies and software that are routinely used in laboratories has now allowed for a more diverse novel range of methods to determine sperm concentrations more rapidly. The aim of this study was to compare 3 such novel methods developed in our laboratory, including a new flow cytometry approach, image analysis, and a fluorescent plate reader, with more conventional methods (hemocytometry, spectrophotometry, and Microcell analysis). Fifteen ejaculates were collected from 13 bulls at an artificial insemination center. The semen samples were analyzed for sperm concentration using a spectrophotometer, hemocytometry, and a novel flow cytometry technique based on counting a fixed volume of fluid. The raw ejaculate was also diluted fivefold in a long‐term diluent and sent overnight to another laboratory, where sperm numbers were assessed using Microcells, an image analysis system, and a fluorescent plate reader. Each ejaculate was assessed 5 times using each of the methods described in order to determine the coefficient of variation for each method. Comparisons between methods were determined using correlation and limits of agreement. The flow cytometry results showed the lowest coefficient of variation (2.3%), with the plate reader showing the highest coefficient of variation (20.0%). There was no significant difference between any of the methods used, and none of them consistently over‐ or underestimated numbers when compared against each other. It is concluded that flow cytometry showed the highest repeatability of results. However, the method employed by each laboratory should be determined based on a range of factors, including cost, convenience, sample size, and number of ejaculates to be assessed.
Sonic Hedgehog Pathway Inhibition Alters Epididymal Function as Assessed by the Development of Sperm Motility
Authors: Turner Terry T. , Bang Hyun J. , Attipoe Sharon A. , Johnston Daniel S. , Tomsig Jose L.
Published: February 2006

ABSTRACT:The sonic hedgehog (Shh) signaling pathway plays a role in pattern orientation in the developing embryo and has been shown to be required for development of the prostate and external genitalia. Recent evidence has shown that important elements of the Shh pathway are also expressed in the adult mouse epididymis at both the gene and protein levels. The objective of the present investigation was to refine the expression pattern of Shh in the mouse epididymis and to determine if the Shh pathway is important for epididymal function vis‐à‐vis sperm maturation. The former was achieved by microarray analysis of Shh expression in all segments of the mouse epididymis, and the latter was determined by 14‐day administration of cyclopamine, a Shh pathway inhibitor, followed by a microassay for the activation and duration of cauda epididymal sperm motility. Shh pathway inhibition was monitored by semiquantitative reverse transcriptase—polymerase chain reaction for expression of epididymal Gli1 and Gli3. The Gli family of transcription factors is commonly activated and regulated by Shh pathway activation. Cyclopamine treatment reduced Gli1 expression by 61% and initiation of cauda sperm motility by 50%. Gli3 expression was reduced by approximately 50%. Subsequent cluster analysis using the microarray data on epididymal gene expression highlighted several potential target genes for the Shh pathway, the most prominent of which is prostaglandin D2synthase. These results indicate that an operating Shh pathway is important in the murine epididymis for the development of sperm motility and implies a role for Shh signaling in adult epididymal function.
Annelated perylenes: Benzenoid molecules violating the Kekulé-structure-based cyclic conjugation models
Authors: Gutman Ivan , Furtula Boris , Djurdjevic Jelena , Kovacevic Rradmila , Stankovic Sonja
Published: February 2006

Several currently used models for assessing the extent of cyclic conjugation in benzenoid hydrocarbons, all based on Kekul?-type structural formulas predict that there is no cyclic conjugation in the central, "empty", ring of perylene and its annelated derivatives. In this paper it is shown that in some annelated perylenes the cyclic conjugation in the "empty" ring (measured by its energy-effect) may be unexpectedly high. Therefore, in the case of these annelated perylenes, the Kekul?- structure-based models fail. The cause for such an "anomalous" behavior of annelated perylenes is discussed.
Influence of easily ionised elements on the delayed responses of the emission intensities of an analyte in a powdermodulated U-shaped argon stabilised DC arc plasma with an aerosol supply
Authors: Kuzmanovic Miroslav , Savovic Jelena , Pavlovic Mirjana , Stoiljkovic Milovan , Antic-Jovanovic Ankica , Marinkovic Momir
Published: February 2006

The current of a U-shaped argon stabilised DC arc was square modulated with a 40 Hz repetition frequency between 6 and 3 A. The delayed line intensity responses to the modulation of the arc current were investigated using calcium as a representative analyte. The intensities of both the atomic and ionic lines were monitored at different distances from the arc axis in the presence of various concentrations of the easily ionised element. Temporal evolutions were monitored on a millisecond time scale. It was found that the responses of the line intesity to the arc current change strongly depended on the observed radial position, especially in the vicinity of the arc axis. The obtained results showed a significant influence of even small amounts of the easily ionised element on the excitation and transport of the analyte and indicated a way of possibly improving the analytical capabilities of the excitation source.
Study on phenol oxidation with H2O2
Authors: Zhang Jin , Tang Ying , Xie Jia-Qing , Li Jian-Zhang , Zeng Wei , Hu Chang-Wei
Published: February 2006

Two new ligands, 1-hydroxy-5- 4-(2-hydroxybenzylideneamino)pheno - xy -3-oxapentane (HL1) and 1-methoxy-5- 4-(2-hydroxybenzylideneamino)pheno - xy -3-oxapentane (HL2), and their Mn(III) complexes were synthesized and characterized. The two new Schiff base Mn(III) complexes were used to mimic peroxidase in the oxidation of phenol by hydrogen peroxide. The effect of the mole ratio of H2O2 to the complex, pH and temperature on the reaction rate was investigated. The mechanism of the catalytic oxidation is discussed. A kinetic mathematic model for the oxidation of phenol catalyzed by Schiff base Mn(III) complexes has been constructed.
Some aspects of nickel electrodeposition in the presence of a magnetic field
Authors: Nikolic Nebojsa
Published: February 2006

Nickel deposits obtained from a Watt solution both without and with a perpendicularly oriented magnetic field were examined by scanning electron microscopy (SEM). The nickel deposit obtained without an imposed magnetic field was very rough, with a clearly visible clustered structure. The nickel deposit obtained under a perpendicularly oriented magnetic field has a very developed dendritic structure, which can be denoted as arboreous ? bead dendritic structure. The ob- served difference is essentially ascribed to the effect of a magnetic field on the magnetic properties of nickel.
Gamma-radiation induced damage of proteins in the thick fraction of egg white
Authors: Vuckovic Marija , Radojcic Marija , Milosavljevic Bratoljub
Published: February 2006

The thick fraction of egg white saturated with either N2O or Ar was irradiated in the dose range 1.5-45 kGy at 60Co gamma source. The gel structure decomposition and other processes accompanied with changes in protein molecular mass were followed by Sephadex G-200 exclusion chromatography, denaturing SDS-polyacrylamide gel electrophoresis, viscosity and turbidity measurements. The complex behavior of viscosity was observed in the N2O saturated sample (where the hydrated electron was converted into the OH radical); the initial abrupt decrease that gradually slows down reaching the minimum at 12 kGy (?min = 2.7 mPa s) followed by the slow rise was measured. The Ar saturated sample ([eaq-]?[OH]) showed both the significantly faster initial decrease and lower viscosity minimum (?min = 2.2 mPa s). The combined Sephadex G-200 exclusion chromatography and denaturing SDS-polyacrylamide gel electrophoresis data revealed that the three-dimensional egg white (hydrated) gel structure was (efficiently) decomposed even in the N2O saturated sample. The protein scission was detected in the entire dose range studied, while the protein agglomeration is not noticed at low doses (around 1.5 kGy); however, it dominates at higher doses. In the highest dose region studied, the loss of structure in SDS-PAGE chromatograms indicates that the agglomerates are formed from protein fragments rather than from intact proteins. The continuous linear increase in turbidity was measured. The results obtained indicate that ionizing radiation causes the breakdown of the protein network of the thick fraction of egg white via the reduction of S-S bridges by the hydrated electron and the protein fragmentation due to the direct action of ionizing radiation. The protein agglomeration is initiated by the reaction of the OH radical; its inefficiency at low doses is attributed to the glucose antioxidant properties and radical immobility. .
Gas hold-up in a three-phase reciprocating plate column
Authors: Nikolic Ljubisa , Nikolic Vesna , Veljkovic Vlada , Skala Dejan
Published: February 2006

The influence of the geometry of a reciprocating plate column (diameter), superficial gas velocity, vibration intensity and content of the solid phase in the column on the gas hold-up in a three phase column (G-L-S) were investigated in this study. For comparison, the gas hold-up was also analyzed in a gas-liquid system (G-L) in the same type of column. Good agreement between the experimentally determined values of the gas hold-up and those calculated on the basis of the derived correlation for the G-L and G-L-S system was obtained.
Fracture, grinding, mechanical activation and synthesis processes in solids under mechanical action
Authors: Chaikina M.V. , Aman Sergej
Published: February 2006

The parameters of mechanical action on solids were determined for apatite and quartz as examples, providing separation between fracture, grinding and mechanical activation processes in solids. The texture, structural and chemical changes accompanying these processes in the samples under investigation are shown. The data on mechanochemical synthesis of isomorphous apatite modifications in multicomponent systems are reported. A reversible character of mechanochemical activation and mechanochemical synthesis is discovered.
Modeling of dimensional changes during sintering
Authors: Drndarevic D. , Djuricic M.
Published: February 2006

An approach to modeling the behavior of dimensions of PM parts during the sintering process for the prediction of dimensional changes is given. The model is developed on the basis of significant process factors by applying a multilayer neural network architecture with the backpropagation learning algorithm. Results of the simulation in the form of diagrams and tables are presented. The presented model gives better results than the one based on statistical analysis of experimental data, i.e. less total mean approximation errors of the part dimensions for 11.4%. A practical result of the model is the determination of compact dimensions to compensate for dimensional changes during sintering. .
The impure retardation of interparticle joining surface migration
Authors: Dorofeyev V.Yu. , Yegorov S.N.
Published: February 2006

An analysis of migration of the interparticle joining surface in the conditions of impure retardation is presented. An expression quantitatively connecting retardation work with the initial segregation on a metal surface and temperature conditions of formation of hot-deformed powder material is derived. The values of retardation work are calculated when some types of iron powder are used as the initial material. .
Examining mathematics attitude in a TIMSS 2003 pilot research
Authors: Kadijevic Djordje
Published: February 2006

Apart from the data on test reliability, the psychometric features of the TIMSS variables are not officially available. It is therefore not clear whether the TIMSS findings capture real educational trends. Being concerned with mathematics attitude, the aim of this research was to determine the psychometric values of a mathematics attitude scale derived from a student questionnaire, and, if these are appropriate, to examine the relation of mathematics attitude to gender and mathematics achievement, and search for gender differences in the applied mathematics attitude indicators. By using a sample of 89 seventh-grade students involved in a TIMSS 2003 pilot research, it revealed the following findings: (a) the representativity reliability, homogeneity and validity of the applied attitude scale were acceptable, (b) attitude to mathematics was related to mathematics achievement, (c) gender differences in mathematics attitude were not found and (d) gender differences in the applied indicators were only present for the statement "I need to do well in mathematics to get into the faculty of my choice" where males expressed a higher agreement than females.
Children’s questions as a base of teaching
Authors: Pavlovic Branka
Published: February 2006

The paper considers interrelationships between children?s questions and teaching and learning in the light of experimental studies on the role and aim of children?s questions in Nature and Society teaching in the third grade of primary school. The experiment comprising two parallel groups was carried out on the sample of 150 respondents from two primary schools in Sabac during the second term of the academic year 2002/2003. The present paper involves a portion of the results obtained for the type of questions children asked during teaching process as classified by independent observers; average distribution of some types of questions; qualitative analysis of discussions conducted with children after two classes where identical teaching content was presented in groups E and K; qualitative analysis of two interviews conducted with teachers after those classes in groups E and K; observers? general impression of classes in groups E and K. The results showed that teaching based on children?s questions encourages children?s proactive attitude towards learning and leads to its higher cognitive efficiency and that children express a high degree of satisfaction by participating in thus organized work during classes and preference of atmosphere present in the classroom during such classes compared to the atmosphere during classes managed in a traditional way. Communication between children and between teacher and children is less formal, more relaxed and dynamic, which all produces motivational effects on children makes them more engaged in learning during teaching whose base is in their questions and not in teaching managed by teacher?s questions.
Non-intellectual predictors of achievement in mathematics
Authors: Milosevic Nikoleta , Janjetovic Dragan
Published: February 2006

Findings presented herein are a part of a large international study of primary school final grade student achievement in mathematics and science (TIMSS 2003). Studies were also conducted on the degree of correlation between student family socioeconomic status, mathematical self-concept and achievement in mathematics. Pilot studies, whose findings are discussed comprised 112 seventh-grade students. "Family socioeconomic status" was defined by variables such as the number of family members, economically disadvantaged/affluent home, and parental educational status. "Mathematical self-concept" was defined as one of the more narrow domains of academic self-concept. "Achievement in mathematics" was measured by the test assessing two dimensions of knowledge of mathematics: content and cognitive skills. The analyses of partial correlations indicate that the most significant predictors of achievement in mathematics test are as follows mathematical self-concept, mother?s educational status and some indicators of family socioeconomic status (access to the Internet, number of household members, number of books available at home). Concerning the correlation found between family characteristics and mathematical self-concept and achievement in mathematics, the developers of current changes in mathematics teaching should not disregard the findings of this study.
Development of cognitive abilities as educational goal
Authors: Milanovic-Nahod Slobodanka , Saranovic-Bozanovic Nadezda
Published: February 2006

The present paper sets out to consider cognitive abilities development depending on learning and educational goals. Three standpoints and their effects on the quality of cognition are opposed: determination of tasks and goals beforehand, non-determination of tasks and goals beforehand, and alternative models where general and specific goals are planned specification being left to curriculum executors. Thereafter, consideration is given to the learning theories where it is insisted either upon learner?s individual activities or upon planning of learning context which contains interrelations between teachers, learners and contents. Emphasis is placed on a discrepancy between theoretical ideas providing good reasons for independently constructed knowledge evaluation, on the one hand, and school practice that commonly does not attribute great importance to such knowledge on the other hand. How the development of cognitive abilities will proceed in teaching depends largely on teachers themselves - their understanding of tasks and goals, qualifications they possess for school subject they teach manner of executing instruction, and familiarity with student personality needs. We can accept the standpoint that we need the theory focusing straight on education, but must be broad enough to embrace both individual and contextual perspective as well as activities of both teachers and students.
Measures and programs for preventing violence in school
Authors: Gasic-Pavisic Slobodanka
Published: February 2006

In many countries across the world schools are no longer a safe place for both students and school staff. Violence in school is an issue scarcely studied in Serbia and there are few articles in domestic professional literature. At national and local level there are not developed strategies nor programs for preventing violence among students in our schools. There are no data about planned, systematic and organized prevention of violence in the practice of our schools. The data obtained by investigations indicate that it is necessary to apply adequate programs for preventing violence among students in our schools, despite the finding that violence in school is not that much conspicuous and serious problem like in other countries (USA Israel, Japan, Austria, Germany). On the basis of relevant literature review the present paper high?lights some very popular and less notorious measures and prevention programs applied in various countries. The aim of the paper is to transmit basic and essential pieces of information so as to gain insight into diverse existing approaches to prevention of violent behavior in school hopefully to encourage our schools to pay more attention to preventing violence in school as soon as possible before it is too late.
From the ‘Culture Wars’ to the Conservative Campaign for Campus Diversity: Or, How Inclusion Became the New Exclusion
Authors: Giroux Susan Searls
Published: February 2006

This article explores the new conservative assault on the university and the relative silence on the part of progressives in response to this challenge. In part, this apparent retreat is a consequence of the vulnerabilities and anxieties of workers in the academy that result from the ongoing corporatization of the university as well as the pervasive culture of fear that permeates the USA in the wake of 9/11, which tends to punish critique as anti-American. As important as such factors are, the current analysis focuses more inwardly on processes of internalization and normalization of the tenets of professionalism and (neo)liberalism in the post-civil rights American academy. Upon careful reexamination of the ‘culture wars’ of the 1980s and 1990s, it locates part of an explanation for such confounding quiet in the ideals that marked the university's ‘multicultural turn.’ The often limp endorsement and bland acceptance of principles such as ‘nondiscrimination,’ ‘diversity,’ and ‘openness’ in the abstract enabled the Right's ruthless appropriation of the vision and language of civil rights, turning fact and history on their heads.
Audit Cultures, Commodification, and Class and Race Strategies in Education
Authors: Apple Michael W.
Published: February 2006

The author discusses some of the ways in which certain elements of conservative modernization have had an impact on education at multiple levels. He points to the growth of commodifying logics and the audit culture that accompanies them. In the process, he highlights a number of dangers currently being faced. However, he urges us not to assume that these conditions can be reduced to the automatic workings out of simple formulae. He argues that we need a much more nuanced and complex picture of class relations and class projects to understand what is happening – and a more sensitive and historically grounded analysis of the place of racial dynamics in the vision both of ‘a world out of control’ that needs to be policed and of ‘cultural pollution’ that threatens ‘real knowledge’ in the growth of markets and audit cultures. Thus, Michael Apple also urges his readers to listen carefully to the critiques coming from collective voices within oppressed communities and to not assume that one can read off their positions by reducing their agency to simply expressions of rightist ideological formula. Becoming more nuanced about such constitutive dynamics will not guarantee that we can interrupt the tendencies upon which he focuses here. But it is one essential step in understanding the genesis of what is at stake in a serious politics of interruption.
Multiculturalism, Recognition and Abjection: (re)Mapping Italian Identity
Authors: Kowalczyk Jamie , Popkewitz Thomas S.
Published: February 2006

This article focuses Italy's conversations about multiculturalism as dual processes of national homogeneity and abjection with respect to its growing conversation around citizenship, national identity and immigration. Abjection is a concept that directs attention to border-making through dual cultural practices of recognizing and managing difference; these practices, however, simultaneously produce ghettoes of difference within the imaginary of the nation. Italian schools, along with other EU member schools, have been designated as a central institution for the production of the new citizen, both European and, in this case, Italian. Through an analysis of documents from the European Union and Italian Ministry of Education, one can begin to map the multiple multicultural citizenships that make up these relational new citizens. This work gives intelligibility to particular dispositions, particular practices, ways of being and systems of reasoning connected to the new multicultural citizen. In doing so, it also makes visible the non-European, non-Italian and non-multicultural within multicultural, European Italy.
Synthesis and Potent Antimicrobial Activities of Some Novel Retinoidal Monocationic Benzimidazoles
Authors: Ates‐Alagöz Zeynep , Alp Mehmet , Kus Canan , Yildiz Sulhiye , Buyukbingöl Erdem , Göker Hakan
Published: February 2006

Several 2‐(5,5,8,8‐tetramethyl‐5,6,7,8‐tetrahydronaphthalen‐2‐yl)‐1H‐benzimidazole‐5‐carboxamidine analogues were synthesized for their antibacterial and antifungal activities against S. aureus, Methicillin‐resistant S. aureus (MRSA), C. albicans, and C. krusei. MIC values of the targeted compounds 43‐58 are comparable to those of Fluconazole and Sultamicillin. The most potent compounds, 51 and 53, showed MIC values as 0.78 and 1.56 μg/mL against S. aureus and C. albicans, respectively.
Synthesis and Characterization of Thiol Containing Furoxan Derivatives as Coligands for the Preparation of Potential Bioreductive Radiopharmaceuticals
Authors: Cerecetto Hugo , González Mercedes , Onetto Silvia , Risso Mariela , Rey Ana , Giglio Javier , León Elsa , León Alba , Pilatti Pierina , Fernández Marcelo
Published: February 2006

The synthesis and characterization of thiol‐containing 1,2,5‐oxadiazole N‐oxide (TONO) derivatives and their use as monodentate coligands for the preparation of 99mTc complexes is presented. 3‐Mercaptomethyl‐4‐phenyl‐1,2,5‐oxadiazol N2‐oxide and 3‐(4‐mercaptophenylmethylidenhydrazinocarbonyloxymethyl)‐4‐phenyl‐1,2,5‐oxadiazol N2‐oxide were successfully synthesized and combined with the tridentate ligand N,N‐bis(2‐mercaptoethyl)‐N′,N′‐diethylethylenediamine (BMEDA) to prepare “3+1 mixed ligand” technetium complexes. The 99mTc complexes were obtained in high yield and radiochemical purity using low concentration of ligand and coligand. An alternative procedure using a xantate and a disulphide precursor of 3‐mercaptomethyl‐4‐phenyl‐1,2,5‐oxadiazol N2‐oxide yielded the same complex. Biological evaluation of the potentiality of the 99mTc complexes as bioreductive radiopharmaceuticals was performed in normal CD1 mice and in mice bearing induced sarcoma. Tumour uptake was moderate but tumour/soft tissue ratio was favourable. Although these results are encouraging, further development is still necessary in order to achieve higher tumour uptake and lower gastrointestinal activity.
Synthesis and Biological Evaluation of Some Hydroxypyrazole Derivatives as Anti‐inflammatory‐Antimicrobial Agents
Authors: Bekhit Adnan A. , Abdel‐Rahman Hamdy M. , Guemei Aida A.
Published: February 2006

Some hydroxypyrazole derivatives 2–7 were synthesized by cyclocondensation of the keto‐ester 1 with hydrazines hydrate or substituted hydrazines followed by reduction and acylation with acetic anhydride or trifluoroacetic anhydride. The newly synthesized compounds were evaluated for their anti‐inflammatory, antimicrobial activities. In addition, the ulcerogenic and acute toxicity profiles were determined. Compounds N‐(4‐(5‐hydroxy‐1‐trifluoroacetyl‐1H‐pyrazol‐3‐yl)phenyl) trifluoroacetamide 4b, 3‐(4‐nitrophenyl)‐1‐(4‐methoxyphenyl)‐1H‐pyrazol‐5‐ol 5b, and N‐(4‐(5‐hydroxy‐1‐methyl‐1H‐pyrazol‐3‐yl)phenyl)trifluoroacetamide 7b were proved to be the most active anti‐inflammatory, antimicrobial agents in the present study with a good safety margin and minimal or no ulcerogenic effect.
Planung für das Schiffshebewerk am Drei‐Schluchten‐Staudamm in China
Authors: Krebs Dorothea , Runte Thomas , Strack Gerhard
Published: February 2006

Zur Beförderung von Passagierschiffen am Drei‐Schluchten‐Staudamm am Yangtze ist in der Nähe der Stadt Yichang ein Senkrecht‐Schiffshebewerk nach dem Gegengewichtsprinzip vorgesehen, das derzeit durch die China Yangtze Three Gorges Project Corporation, Bauherr und Betreiber des Drei‐Schluchten‐Staudamms, geplant wird. Mit der Ausschreibungsplanung ist die “German Design Group”, ein deutsches Joint Venture, bestehend aus Krebs und Kiefer International und Lahmeyer International, beauftragt. Berater des Bauherrn im Sinne eines “Panel of Experts” ist die Bundesanstalt für Wasserbau.
Der Viadukt über das Tarntal bei Millau – Von den ersten Entwurfsgedanken bis zur Fertigstellung
Authors: Virlogeux Michel
Published: February 2006

Der Bau des Viadukts über das Tarntal bei Millau in Mittelfrankreich begann im Oktober 2001 und war im Dezember 2004 vollendet. Der Viadukt mit einer Gesamtlänge von 2460 m umfaßt sechs 342 m lange Hauptfelder, die an sieben Pylonen verankert sind und stellt einen bedeutenden Fortschritt im Entwurf von Schrägseilbrücken dar. Die Autobahn verläuft 270 m über dem Fluß, zwei ihrer Pfeiler sind höher als 230 m. Mit den 87 m hohen Pylonen über der Fahrbahn überragen sie den Eiffelturm. Ausgearbeitet wurden zwei Lösungen, eine in Spannbeton und eine in Stahlbauweise.
Kriechen von Ultrahochfestem Beton (UHFB)
Authors: Tue Nguyen , Ma Jianxin , Orgass Marko
Published: February 2006

Der Aufsatz behandelt das Kriechverhalten von ultrahochfestem Beton (UHFB) mit einer Druckfestigkeit von 150 N/mm2 und höher. Durch Variation der Beanspruchungen im Bereich zwischen 28% und 85% der Betonfestigkeit zum Belastungszeitpunkt konnte der Übergang vom linearen zum nichtlinearen Kriechen ermittelt werden. Ein Vergleich der Versuchergebnisse mit dem Ansatz der neuen DIN 1045‐1 verdeutlicht die Notwendigkeit weiterer Untersuchungen des Kriechverhaltens von UHFB, insbesondere bei Belastung im jungen Betonalter und bezüglich der zeitlichen Entwicklung des Kriechens.
Zum Tragverhalten von Mauerwerksbauten unter Erdbebenbelastung
Authors: Ötes Atilla , Löring Stephan
Published: February 2006

Das Bemessungsziel bei der Erdbebenauslegung eines Bauwerks ist das Sicherstellen einer ausreichenden Tragfähigkeit unter Berücksichtigung der Duktilität der Konstruktion. Mit experimentellen Untersuchungen an geschoßhohen Wänden wurde an der Universität Dortmund das Widerstands‐ und Verformungsverhalten von aussteifenden Mauerwerkswänden unter simulierten Erdbebenbelastungen bis zum Versagen identifiziert. Das nichtlineare Tragverhalten der Wände wurde in bezug auf Tragfähigkeit und Duktilitätspotential ausgewertet. In Abhängigkeit der Art des erreichten Grenzzustands zeigten die Mauerwerkswände unterschiedliche Werte für Duktilität. Mit rechnerischen Betrachtungen konnte gezeigt werden, daß innerhalb bestimmter Grenzen durch die Abstimmung der Konstruktionsparameter duktile Grenzmechanismen erreicht werden können. Ausgehend von repräsentativen Konfigurationen für aussteifende Wände wurden für Reihen‐ und Mehrfamilienhäuser die Tragwerksduktilität und der damit korrespondierende Verhaltensbeiwert für den Erdbebennachweis (vgl. EC 8 und DIN 4149) abgeschätzt.
Johann August Röbling (1806–1869) – Vom preußischen Bauconducteur zum amerikanischen Brückenbauer und Industriellen
Authors: Patzschke Fritz
Published: February 2006

Anläßlich der 200. Wiederkehr seines Geburtstages wird an das Wirken und Werden des deutschstämmigen Amerikaners und Absolventen der preußischen Bauakademie, Johann August Röbling aus Mühlhausen in Thüringen, erinnert. Mit dem Wissen des alten Europa hat er großartige Brücken und ein industrielles Imperium, die Drahtseilproduktion, im Amerika des 19. Jahrhunderts geschaffen.
Separation of catechin compounds from different teas
Authors: Jin Yinzhe , Jin Chun Hua , Ho Row Kyung
Published: February 2006

Catechin compounds from Korean and Chinese green tea, and pu‐erh, Indian black, Longjing, Tieguanyin, Bamboo, Jasmine, Oolong, Flower, Red teas, as potential anticancer and antioxidant components, were target material in this work. After extracting the green tea with water at 50°C for 4 h, the extract was partitioned with water/chloroform, which was best suited to remove caffeine impurity from the extract. Further, the resulting extract was partitioned with water/ethyl acetate to deeply purify the five catechin compounds epigallocatechin, (+) catechin, epicatechin, epigallocatechin gallate and epicatechin gallate. The extracted samples were analyzed by reversed‐phase high performance liquid chromatography. The mobile phase applied was the binary system of A (water/acetic acid, 100/0.1 vol%) and B (acetonitrile/acetic acid 100/0.1 vol%) from 90:10 to 70:30 (A:B vol%) in a linear gradient over 30 min time. The amount of catechin compounds extracted from Chinese green tea was 114.65% higher than from the Korean green tea. Comparing various tea sorts, the green teas contained more than 1.7 times of the five catechin compounds contained in other teas.
Cancer immunotherapy
Authors: Schuster Manfred , Nechansky Andreas , Kircheis Ralf
Published: February 2006

Cancer is the second leading cause of death in the industrialized world. Most cancer patients are treated by a combination of surgery, radiation and/or chemotherapy. Whereas the primary tumor can, in most cases, be efficiently treated by a combination of these standard therapies, preventing the metastatic spread of the disease through disseminated tumor cells is often not effective. The eradication of disseminated tumor cells present in the blood circulation and micro‐metastases in distant organs therefore represents another promising approach in cancer immunotherapy. Main strategies of cancer immunotherapy aim at exploiting the therapeutic potential of tumor‐specific antibodies and cellular immune effector mechanisms. Whereas passive antibody therapy relies on the repeated application of large quantities of tumor antigen‐specific antibodies, active immunotherapy aims at the generation of a tumor‐specific immune response combining both humoral and cytotoxic T cell effector mechanisms by the host's immune system following vaccination. In the first part of this review, concurrent developments in active and passive cancer immunotherapy are discussed. In the second part, the various approaches for the production of optimized monoclonal antibodies used for anti‐cancer vaccination are summarized.
Effect of Vitreoscilla hemoglobin on production of a chemotherapeutic enzyme, L‐asparaginase, by Pseudomonas aeruginosa
Authors: Geckil Hikmet , Gencer Salih , Ates Burhan , Ozer Ufuk , Uckun Mirac , Yilmaz Ismet
Published: February 2006

The production of L‐asparaginase, an enzyme widely used in cancer chemotherapy, is mainly regulated by carbon catabolite repression and oxygen. This study was carried out to understand how different carbon sources and Vitreoscilla hemoglobin (VHb) affect the production of this enzyme in Pseudomonas aeruginosa and its VHb‐expressing recombinant strain (PaJC). Both strains grown with various carbon sources showed a distinct profile of the enzyme activity. Compared to no carbohydrate supplemented medium, glucose caused a slight repression of L‐asparaginase in P. aeruginosa, while it stimulated it in the PaJC strain. Glucose, regarded as one of the inhibitory sugars for the production L‐asparaginase by other bacteria, was determined to be the favorite carbon source compared to lactose, glycerol and mannitol. Furthermore, contrary to common knowledge of oxygen repression of L‐asparaginase in other bacteria, oxygen uptake provided by VHb was determined to even stimulate the L‐asparaginase synthesis by P. aeruginosa. This study, for the first time, shows that in P. aeruginosa utilizing a recombinant oxygen uptake system, VHb, L‐asparaginase synthesis is stimulated by glucose and other carbohydrate sources compared to the host strain. It is concluded that carbon catabolite and oxygen repression of L‐asparaginase in fermentative bacteria is not the case for a respiratory non‐fermentative bacterium like P. aeruginosa.
Manufacturing of recombinant therapeutic proteins in microbial systems
Authors: Graumann Klaus , Premstaller Andreas
Published: February 2006

Recombinant therapeutic proteins have gained enormous importance for clinical applications. The first recombinant products have been produced in E. coli more than 20 years ago. Although with the advent of antibody‐based therapeutics mammalian expression systems have experienced a major boost, microbial expression systems continue to be widely used in industry. Their intrinsic advantages, such as rapid growth, high yields and ease of manipulation, make them the premier choice for expression of non‐glycosylated peptides and proteins. Innovative product classes such as antibody fragments or alternative binding molecules will further expand the use of microbial systems. Even more, novel, engineered production hosts and integrated technology platforms hold enormous potential for future applications. This review summarizes current applications and trends for development, production and analytical characterization of recombinant therapeutic proteins in microbial systems.
Molecular Structures and Magnetism of Mn12 Nanomagnets Containing the 3‐Thiophenecarboxylate Ligand (Eur. J. Inorg. Chem. 4/2006)
Authors: Lim Jin Mook , Do Youngkyu , Kim Jinkwon
Published: February 2006

The cover picture shows the Mn12 single‐molecule magnet (SMM), which has a 3‐thiophenecarboxylate ligand and is formed by the ligand substitution reaction of Mn12‐ac with 16 equiv. of 3‐thiophenecarboxylic acid in toluene. The reaction of Mn12‐ac with 17 equiv. of 3‐thiophenecarboxylic acid affords a different Mn12 SMM that shows a more distorted structure and has a faster relaxation rate. The Mn12 SMM is strongly anchored on the gold surface through the sulfur atoms of the thiophenyl group. The Mn12 molecular film on Au(111) was characterized by XPS, STM, and AFM. Further details are discussed in the article by J. Kim et al. on p. 711 ff.