bluuebunny/crossref_metadata_2025 huggingface dataset:
Rasterreflexions-Photogrammetrie zur Messung spiegelnder Oberflächen (Reflection Grating Photogrammetry for the Measurement of Specular Surfaces)
Authors: Petz Marcus , Tutsch Rainer
Published: July 2004

Die berührungslose dreidimensionale Messung spiegelnd reflektierender Freiformflächen bereitet trotz neuerer Fortschritte auf dem Gebiet der Asphärenprüfung noch immer erhebliche Schwierigkeiten. Die in diesem Beitrag vorgestellten geometrisch-optischen Messverfahren nach dem Rasterreflexionsprinzip ermöglichen durch Kombination mit photogrammetrischen Auswertetechniken die punktweise und eindeutige Erfassung nahezu beliebig geformter spiegelnder Oberflächen.
Extension of the age‐of‐fluid method to unsteady and closed‐flow systems
Authors: Jongen T.
Published: July 2004

The age‐of‐fluid method is revisited to evaluate and extend it from its traditional application domain of steady, open‐flow systems to general unsteady and/or closed‐flow systems. The most significant change in the approach comes from the definition of the age of the fluid in a purely kinematic way as a tagging variable, and based solely on the velocity field of the underlying fluid, whereas all the other methods proposed to date somehow determine the age indirectly by tracking an injected tracer material in the flow domain. The resulting mathematical formulation makes it possible to specify the age at arbitrary positions within the flow domain, while being formally very similar to the classical age‐of‐fluid transport equations previously obtained. This has the benefit of clarifying a number of issues such as the treatment of the diffusion coefficient, the definition of suitable boundary conditions, the validation in unsteady flow conditions, and the extension to closed‐flow domains. © 2004 American Institute of Chemical Engineers AIChE J, 50: 2020–2037, 2004
Demography, life history, and social structure in Propithecus diadema edwardsi from 1986–2000 in Ranomafana National Park, Madagascar
Authors: Pochron Sharon T. , Tucker W. Troy , Wright Patricia C.
Published: July 2004

Prosimian lemurs differ fundamentally from anthropoid primates in many traits related to social structure. By exploring the demography of Milne‐Edwards' sifakas (Propithecus diadema edwardsi), and comparing it to other well‐studied primates, we explore the effect of demographic and life‐history factors on social structure. Specifically, we compare lemur survivorship and fertility patterns to two published composite models: one created for New World and another created for Old World monkeys. Using longitudinal data collected on individual Propithecus diadema edwardsi from four study groups from 1986–2000 in Ranomafana National Park, Madagascar, we quantify 1) group composition, 2) birth seasonality, 3) interbirth interval, 4) life‐table values, and 5) population growth estimates. The mortality, survivorship, and life‐expectancy schedules indicate high infant and juvenile mortality. Fertility remains high until death. The intrinsic rate of increase and net reproductive rate indicate a shrinking population. We suggest that high mortality rather than low fertility causes the observed population decline. While sifaka survivorship closely resembles New World patterns, fertility resembles Old World patterns, i.e., like New World monkeys, few sifakas survive to reproductive age, and those that do, reproduce at a slow rate resembling the Old World pattern. This necessarily impacts social structure. An adult sifaka at the end of her lifespan will have one only daughter who survives to reproductive age, compared to 3.4 for New World or 2.7 for Old World monkeys. Demography limits the formation of large kin‐based groups for sifakas, and survivorship and fertility patterns do not easily permit sifakas to form large same‐sex family groups. Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.
Molar size and shape variations among Asian colobines
Authors: Willis Mary S. , Swindler Daris R.
Published: July 2004

Despite decades of research, little is known about morphometric differences within the dentition of Asian colobines. Although some differences, such as the M3 hypoconulid, are often cited as distinct among genera, no comprehensive assessment has been made. The objectives of this study were to document size and shape differences in third molars in eight Asian colobine genera, including Kasi, Nasalis, Presbytis, Pygathrix, Rhinopithecus, Semnopithecus, Simias, and Trachypithecus, and to quantify length differences for all molars in order to understand the potential impact of an occlusal surface area that includes the hypoconulid. To achieve these objectives, the most extensive survey yet published of Asian colobine dentition was conducted. Differences within and among genera for continuous and categorical variables were analyzed using descriptive statistics, chi‐square, t‐tests, and post hoc comparisons. Results indicate that species of Presbytis differ from all other Asian colobines in both the size and shape of the maxillary and mandibular third molars. Specifically, M3 of Presbytis is relatively shorter in length and less likely to exhibit a hypoconulid optimally positioned for occlusion with M3. Moreover, Presbytis expresses concomitant changes in the maxillary third molar such as absence of a distal shelf and/or a distal cusp with separated crests. We conclude that shape and size changes impact the molar size sequence patterns of Presbytis, setting this genus apart from all other Asian colobine taxa. These differences may reflect variation in overall body size, dietary adaptation, and phylogeny. Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.
Role of carnivores in the accumulation of the Sterkfontein Member 4 hominid assemblage: A taphonomic reassessment of the complete hominid fossil sample (1936–1999)
Authors: Pickering Travis Rayne , Clarke Ron J. , Moggi‐Cecchi Jacopo
Published: July 2004

New taphonomic data on the Sterkfontein Member 4 (South Africa) fossil hominid assemblage are presented. The previous estimate of hominid individuals represented in the deposit (45) is increased to 87. New minimum numbers of hominid skeletal elements are provided, and incidences of bone surface damage inflicted by prehistoric biological agents are summarized. The hominid sample from Member 4 is composed predominately of gnathic remains and has a paucity of postcrania. This dearth of postcrania limits, to some extent, inferences about the formation of the Sterkfontein assemblage. However, carnivore tooth marks on some fossil specimens and an overall broad similarity in patterns of skeletal part representation between Sterkfontein and primate bone assemblages created by extant carnivores suggest that carnivores did have some involvement in the accumulation of the fossil hominid assemblage. Thus, this study provides support for the “carnivore‐collecting hypothesis” of Brain (Brain [1981] The Hunters or the Hunted? Chicago: University of Chicago Press), which implicates large carnivores as prominent collecting agents of hominid body parts in Sterkfontein Member 4. Evidence of bone surface damage is, however, too scant to make confident inferences about specific carnivore taxon/taxa involved in hominid bone collection at the site. Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.
DYS19 and DYS199 loci in a Chilean population of mixed ancestry
Authors: Cifuentes L. , Morales R. , Sepúlveda D. , Jorquera H. , Acuña M.
Published: July 2004

The current Chilean population originated from admixture between aboriginal populations (Amerindians) and Spanish conquerors of European origin. Consequently, the unions that gave rise to the Chilean population were chiefly between Spanish males and aboriginal females, and not the converse. To test the hypothesis that the Y chromosome of the Chilean population is mainly of Spanish origin, while the other chromosomes are from mixed (European and aboriginal) origin, we studied the DYS19 and DYS199 loci in two samples. One sample was obtained from a high socioeconomic stratum, while a second sample was from a low stratum. We studied male blood donors (N = 187) from Santiago, the capital of the country. Subjects were typed for the autosomal ABO and Rh (locus D) blood groups, and for the Y‐linked DYS19 and the DYS199 loci, reported as Y‐chromosome haplotypes. The aboriginal admixture was estimated for each genetic marker. The percentage of aboriginal admixture was 38.17% for the ABO system and 31.28% for the Rh system in the low socioeconomic stratum and 19.22% and 22.5%, respectively, in the high stratum. Y‐chromosome haplotype frequencies constructed from the DYS19 and DYS199 loci demonstrated that the main haplotypes were DYS19*14/DYS199 C, as is often the case with many European populations, and DYS19*13/DYS199 C. The aboriginal admixture from Y‐haplotype frequencies was estimated to be 15.83% in the low socioeconomic stratum and 6.91% in the high stratum. These values are lower than the values found using autosomal genetic markers, and are consistent with the historical background of the population studied. This study highlights the population genetic consequences of the asymmetric pattern of genome admixture between two ancestral populations (European and Amerindian). Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.
Interferon‐β stabilizes barrier characteristics of brain endothelial cells in vitro
Authors: Kraus Jörg , Ling Anne K. , Hamm Stefan , Voigt Kay , Oschmann Patrick , Engelhardt Britta
Published: July 2004

Multiple sclerosis (MS) is accompanied by a breakdown of the blood–brain barrier (BBB) leading to edema formation and aggravation of the disease. Interferon‐β (IFN‐β) has been approved for the treatment of MS and besides its immunomodulatory effects has been demonstrated to lead to a stabilization of BBB integrity in vivo. To investigate whether human recombinant IFN‐β exerts direct effects on the BBB, we used an in vitro BBB model in which brain endothelial cells in coculture with astrocytes form a tight permeability barrier for 3H‐inulin and 14C‐sucrose. Removal of the astrocytes from the coculture or alternatively addition of histamine resulted in an increased paracellular permeability for small tracers across the brain endothelial cell monolayer. Strikingly, in the presence of IFN‐β, permeability increase under both conditions was inhibited. Permeability changes were accompanied by minor changes in the staining for tight junction–associated proteins in brain endothelial cell monolayers. Taken together, our data demonstrate a direct stabilizing effect of IFN‐β on BBB cerebral endothelial cells in vitro that might significantly contribute to the beneficial effects of IFN‐β treatment in MS in vivo. Ann Neurol 2004;56:192–205
Fuel utilization in patients with very long‐chain acyl‐coa dehydrogenase deficiency
Authors: ØRngreen Mette C. , Nørgaard Mette G. , Sacchetti Massimo , Van Engelen Baziel G. M. , Vissing John
Published: July 2004

Fuel utilization in two adult patients with the myopathic form of very long‐chain acyl‐CoA dehydrogenase (VLCAD) deficiency and five healthy subjects was investigated with stable isotopes during exercise at 50% of VO2max. The findings indicate that residual VLCAD activity in the patients is sufficient to maintain normal oxidation of fat at rest, but that fat oxidation rate cannot increase above basal levels during exercise. This can cause an energy deficit and intramuscular accumulation of fat intermediates that may induce the exercise‐induced symptoms.
Folic acid supplementation enhances repair of the adult central nervous system
Authors: Iskandar Bermans J. , Nelson Aaron , Resnick Daniel , Pate Skene J. H. , Gao Peng , Johnson Chenara , Cook Thomas D. , Hariharan Nithya
Published: July 2004

Folic acid supplementation has proved to be extremely effective in reducing the occurrence of neural tube defects (NTDs) and other congenital abnormalities in humans, suggesting that folic acid can modulate key mechanisms for growth and differentiation in the central nervous system (CNS). To prevent NTDs, however, supplemental folate must be provided early in gestation. This suggests that the ability of folic acid to activate growth and differentiation mechanisms may be confined to the early embryonic period. Here, we show that folic acid can enhance growth and repair mechanisms even in the adult CNS. Using lesion models of CNS injury, we found that intraperitoneal treatment of adult rats with folic acid significantly improves the regrowth of sensory spinal axons into a grafted segment of peripheral nerve in vivo. Regrowth of retinal ganglion cell (RGC) axons into a similar graft also was enhanced, although to a smaller extent than spinal axons. Furthermore, folic acid supplementation enhances neurological recovery from a spinal cord contusion injury, showing its potential clinical impact. The results show that the effects of folic acid supplementation on CNS growth processes are not restricted to the embryonic period, but can also be effective for enhancing growth, repair, and recovery in the injured adult CNS. Ann Neurol 2004;56:221–227
SOD2 gene transfer protects against optic neuropathy induced by deficiency of complex I
Authors: Qi Xiaoping , Lewin Alfred S. , Sun Liang , Hauswirth William W. , Guy John
Published: July 2004

Mutations in genes encoding the NADH ubiquinone oxidoreductase, complex I of the respiratory chain, cause a diverse group of diseases. They include Leber hereditary optic neuropathy, Leigh syndrome, and mitochondrial encephalomyopathy with lactic acidosis and stroke‐like episodes. There is no effective treatment for these or any other mitochondrial disorder. Using a unique animal model of severe complex I deficiency induced by ribozymes targeted against a critical complex I subunit gene (NDUFA1), we attempted rescue of the optic nerve degeneration associated with Leber hereditary optic neuropathy. We used adenoassociated virus to deliver the human gene for SOD2 to the visual system of disease‐induced mice. Relative to mock infection, SOD2 reduced apoptosis of retinal ganglion cells and degeneration of optic nerve fibers, the hallmarks of this disease. Rescue of this animal model supports a critical role for oxidative injury in disorders with complex I deficiency and shows that a respiratory deficit may be effectively treated in mammals, thus offering hope to patients. Ann Neurol 2004;56:182–191
Novel haplotypes in 17q21 are associated with progressive supranuclear palsy
Authors: Pastor Pau , Ezquerra Mario , Perez J. Christian , Chakraverty Sumi , Norton Joanne , Racette Brad A. , McKeel Dan , Perlmutter Joel S. , Tolosa Eduardo , Goate Alison M.
Published: July 2004

Progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD) are sporadic neurodegenerative diseases presenting as atypical parkinsonian disorders, characterized by the presence of tau‐positive neurofibrillary tangles. Recently, an extended haplotype (H1E) of 787.6kb that comprises several genes including MAPT showed increased association with PSP. The objective of this study was to determine the size of the H1E haplotype associated with PSP and CBD in different populations and to identify specific subhaplotypes in the background of H1E haplotype. Nineteen single nucleotide polymorphisms (SNPs) in the 17q21 region were genotyped in two case–control samples. The SNPs that were associated with higher risk for the disease in the homozygous state delimit a region of more that 1Mb. Haplotype analyses in the Spanish sample showed that the most frequent haplotype found among the patients (H1E′), which extends 1.04Mb and contains several genes such as MAPT, CRHR1, IMP5, Saitohin, WTN3, and NSF. A specific subhaplotype (H1E′A) was present in 16% of PSP patients but was not observed in the controls. Furthermore, the H2E′A haplotype, was rarely present in the disease group suggesting that it plays a protective role. The identification of these specific subhaplotypes that modify risk for PSP/CBD supports the hypothesis that a pathogenic allele exists in a subgroup of PSP patients. Ann Neurol 2004;56:249–258
PGE2 receptors rescue motor neurons in a model of amyotrophic lateral sclerosis
Authors: Bilak Masako , Wu Liejun , Wang Qian , Haughey Norman , Conant Katherine , St. Hillaire Coryse , Andreasson Katrin
Published: July 2004

Recent studies suggest that the inducible isoform of cyclooxygenase, COX‐2, promotes motor neuron loss in rodent models of ALS. We investigated the effects of PGE2, a principal downstream prostaglandin product of COX‐2 activity, on motor neuron survival in an organotypic culture model of ALS. We find that PGE2 paradoxically protects motor neurons at physiological concentrations in this model. PGE2 exerts its downstream effects by signaling through a class of four distinct G‐protein–coupled E‐prostanoid receptors (EP1–EP4) that have divergent effects on cAMP. EP2 and EP3 are dominantly expressed in ventral spinal cord in neurons and astrocytes, and activation of these receptor subtypes individually or in combination also rescued motor neurons. The EP2 receptor is positively coupled to cAMP, and its neuroprotection was mimicked by application of forskolin and blocked by inhibition of PKA, suggesting that its protective effect is mediated by downstream effects of cAMP. Conversely, the EP3 receptor is negatively coupled to cAMP, and its neuroprotective effect was blocked by pertussis toxin, suggesting that its protective effect is dependent on Gi‐coupled heterotrimeric signaling. Taken together, these data demonstrate an unexpected neuroprotective effect mediated by PGE2, in which activation of its EP2 and EP3 receptors protected motor neurons from chronic glutamate toxicity. Ann Neurol 2004;56:240–248
Adaptation of the attention network in human immunodeficiency virus brain injury
Authors: Chang Linda , Tomasi Dardo , Yakupov Renat , Lozar Carl , Arnold Sheeba , Caparelli Elisabeth , Ernst Thomas
Published: July 2004

Human immunodeficiency virus (HIV)–positive patients commonly have attention and concentration problems. However, it remains unclear how HIV infection affects the attention network. Therefore, blood oxygenation level dependent functional magnetic resonance imaging (BOLD‐fMRI) was performed in 36 subjects (18 HIV and 18 seronegative [SN] controls) during a set of visual attention tasks with increasing levels of attentional load. Compared with SN controls, HIV subjects showed similar task performance (accuracies and reaction times) but decreased activation in the normal visual attention network (dorsal parietal, bilateral prefrontal, and cerebellar regions) and increased activation in adjacent or contralateral brain regions. Cognitive performance (assessed with NPZ‐8), CD4, and viral load all correlated with activated BOLD signals in brain regions that activated more in HIV subjects. Furthermore, HIV subjects activated more than SN controls in brain regions that showed load‐dependent increase in activation (right prefrontal and right parietal regions) but less in regions that showed a saturation effect with increasing load. These findings suggest that HIV‐associated brain injury leads to reduced efficiency in the normal attention network, thus requiring reorganization and increased usage of neural reserves to maintain performance during attention‐requiring tasks. Exceeding the brain reserve capacity may lead to attention deficits and cognitive impairment in HIV patients. Ann Neurol 2004;56:259–272
Tensile behavior and morphology studies of glass‐fiber‐reinforced polymeric in situ hybrid composites
Authors: Liu Hua , Liao Kin
Published: July 2004

The morphology and tensile behavior of an in situ hybrid composite system, based on E‐glass‐fibers, liquid‐crystalline polymers, and Noryl (a modified polyphenylene ether/polystyrene blend) with a hierarchical microstructure containing reinforcements with an order‐of‐magnitude difference in size, were studied. The primary reinforcement was short E‐glass fibers, and the secondary reinforcement was formed by LCP inclusions with submicrometer dimensions generated in situ during fabrication. With an increase in the LCP content, both the geometry and dimensions of the LCP phase in the composites changed, from spherical droplets to ellipsoidal droplets and then to fibrils or lamellar structures. The orientation of the short E‐glass fibers was influenced by this change, and the breakage of the glass fibers during processing was less intensive. The tensile strength of the composites increased moderately with the addition of LCPs and the reduction of the glass‐fiber content. The elastic modulus of the composites did not follow rule‐of‐mixture predictions. This more complicated hybrid effect was attributed to several competing mechanisms. Tensile fractography analysis indicated that the tensile fracture of the composites was dominated by fiber/matrix‐interface failure. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 211–221, 2004
Correlations between the processing variables and morphology of crosslinked polyethylene
Authors: Gulmine J. V. , Akcelrud L.
Published: July 2004

Crosslinked polyethylene (XLPE) is progressively replacing other types of polyethylene in electric cable insulation because of its combination of better mechanical and thermal performance and good dielectric properties. Besides its influence on the mechanical and thermal properties, the morphology plays a very important role in the electrical behavior of XLPE. The morphology has been studied in terms of the crystallinity and crosslinking density. These two apparently independent parameters govern the morphology of XLPE and have been investigated in connection with the systematic variation of the processing parameters (crosslinker concentration, cure time, and temperature). The materials have been characterized in terms of the extent of crosslinking (the gel content), the crosslinking density (the average molecular weight between crosslinks), and the crystallinity. A morphological model is proposed for these materials in terms of the mechanisms and rates of the processes involved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 222–230, 2004
Mathematical modeling of the phase behaviors of solid‐polymer‐electrolyte/salt systems in lithium secondary batteries: The nonrandomness effect
Authors: Pai Sung Jin , Bae Young Chan , Kong Sung Ho , Ryu Si Ok
Published: July 2004

We establish a new melting‐point‐depression theory, based on the modified‐double‐lattice model, that takes into account the local composition concept to describe the phase behaviors of solid‐polymer‐electrolyte/salt systems (modified‐double‐lattice/nonrandom model). In comparison with experimental data, quantitative descriptions of the proposed model show better agreement for the given systems than those of the modified‐double‐lattice model. The systems studied in this work are combinations of poly(ethylene oxide) and zinc halides and of poly(ethylene oxide) and LiCF3SO3. The results show that the nonrandomness effect of the salt distribution plays a major role in determining the eutectic points of the given systems. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 231–237, 2004
Amphiphilic poly(styrene‐b‐ethylene oxide)‐block‐copolymer‐intercalated layered silicate and its nanocomposites with acrylonitrile–butadiene– styrene resin
Authors: Guo Tianying , Hao Guangjie , Song Moudao , Zhang Banghua
Published: July 2004

Amphiphilic poly(styrene‐b‐ethylene oxide) block copolymers were synthesized by sequential anionic copolymerization. Layered silicates intercalated by the block copolymers were prepared via melt intercalation. The effects of the intercalated clay on an acrylonitrile–butadiene–styrene resin were characterized with X‐ray diffraction, transmission electron microscopy, stress–strain measurements in elongation, and thermogravimetric analysis. X‐ray and microscopy results demonstrated that the main structure of the dispersed block‐copolymer‐intercalated clay in the acrylonitrile–butadiene–styrene resin matrix was mono‐ and bundle‐ layered. Further studies demonstrated that the resin showed considerable improvement in its tensile strength, modulus, and thermal stability. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 238–242, 2004
A novel method for synthesis of water‐soluble polypyrrole with horseradish peroxidase enzyme
Authors: Nabid Mohammad Reza , Entezami Ali Akbar
Published: July 2004

A novel water‐soluble, conducting polypyrrole was synthesized by horseradish peroxidase (HRP), in the presence of sulfonated polystyrene, as a polyanionic template. The HRP is an effective catalyst for the oxidative polymerization of pyrrole in the presence of hydrogen peroxide at room temperature. The reaction is sensitive to solution pH and it is performed in pH 2 aqueous solutions. Polymerization of pyrrole by this biological route produced a conducting water‐soluble polypyrrole for the first time. The reaction is benign and in one pot, and the product requires minimal purification. The reversible redox activity of the polypyrrole displays a hystersis loop with pH changes. FT‐IR, UV‐vis absorption spectroscopy, and cyclic voltammetry are used in the characterization of the synthesized polypyrrole. These studies confirm the electroactive and conducting form of polypyrrole, similar to that which has been traditionally synthesized, chemically and electrochemically. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 254–258, 2004
Fabrication of polysulfone asymmetric hollow‐fiber membranes by coextrusion through a triple‐orifice spinneret
Authors: Zhang Yufeng , Du Qiyun , Wu Yun , Wang Peng , Wu Jinghang
Published: July 2004

Polysulfone (PSf) asymmetric hollow‐fiber membranes, which have a dense outer layer but a loose inner layer, were tentatively fabricated by coextrusion through a triple‐orifice spinneret and a dry/wet‐phase inversion process. Two simple polymer dopes were tailored, respectively, for the dense outer layer and the porous inner layer according to the principles of the phase‐inversion process. By adjusting the ratio of the inner/outer extrusion rate, the hollow‐fiber membranes with various thicknesses of outer layers were achieved. The morphology of the hollow‐fiber membranes was exhibited and the processing conditions and the water permeability of the membrane were investigated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 259–266, 2004
Development of macrostructural effects of cold drawing on nylon 6 fibers
Authors: Fouda I. M. , El‐Sharkawy F. M.
Published: July 2004

This work reports measurement of the molecular orientation by two techniques for nylon 6 fibers drawn at room temperature. The changes in the strain and optical parameters are used to obtain some macrostructural parameters to evaluate the cold‐drawing process values of the mechanical orientation functions, [P2(cos θ)], [P4(cos θ)], amorphous and crystalline orientation functions (Fc and Fa), and the molar number of chain segments per unit volume (Ne). Also the crosslink density (N0), the chain entanglement density (Ns), the average optical orientation Fav, the dielectric constant (ε), the dielectric susceptibility (η), the shrinkage stress (ks), and other parameters were calculated. Relationships between the calculated parameters are given. The present study demonstrates changes in the molecular reorientation factors and the obtained new physical properties resulting from cold‐drawing process. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 287–295, 2004
Chiral Resolution of Some Piperidine 2, 6‐dione Drugs by High Performance Liquid Chromatography on Kromasil® CHI‐DMB Column
Authors: Aboul‐Enein Hassan Y.
Published: July 2004

Kromasil® CHI‐DMB chiral stationary phase (CSP) is used to resolve some piperidine‐2, 6‐diones under normal mobile phase mode. Base‐line separation was achieved using hexane and dioxane (90 : 10 v/v) for aminoglutethimide (AG), pyridoglutethimide (PG), cyclohexylaminoglutethimide (ChAG), thioglutethimide (TG), and N‐acetyl aminoglutethimide (AAG). The chromatographic parameters are reported. The chiral recognition mechanisms between the analytes and the CSP depend primarily on hydrogen bonding and/or (π‐π) interactions.
Synthesis and Antiviral Activities of Novel 2′, 4′‐ or 3′, 4′‐Doubly Branched Carbocyclic Nucleosides as Potential Antiviral Agents
Authors: Oh Chang Hyun , Hong Joon Hee
Published: July 2004

In this study, a series of 2′, 4‐′ or 3′, 4′‐doubly branched carbocyclic nucleosides (11, 12, 19, and 20) were synthesized from simple acyclic ketone derivatives as starting materials. The installation of the 4′‐quaternary carbon needed was carried out using a [3, 3]‐sigmatropic rearrangement. In addition, the introduction of a methyl group in the 2′‐ or 3′‐position was accomplished by either Grignard reaction or Horner‐Wadsworth‐Emmons reaction with triethyl‐2‐phosphonopropionate, respectively. Bis‐vinyl was successfully cyclized using a Grubbs' catalyst II. The natural bases (adenine, cytosine) were coupled efficiently using a Pd(0) catalyst. Although all the synthesized compounds were assayed against several viruses, only the cytosine analogue 20 showed moderate antiviral activity against the human cytomegalovirus.
Synthesis and Analgesic and Antiinflammatory Activity of Methyl 6‐Substituted‐3(2H)‐pyridazinone‐2‐ylacetate Derivatives
Authors: Şahina M. F. , Badıçoglu B. , Gökçe M. , Küpeli E. , Yeşilada E.
Published: July 2004

A series of methyl 6‐substituted‐3(2H)‐pyridazinone‐2‐ylacetates 9 were synthesized and their analgesic and anti‐inflammatory effects were evaluated in the phenylbenzoquinone‐induced writhing test (PBQ test) and carrageenan‐induced paw edema method, respectively. Side effects of the compounds were examined on gastric mucosa. None of the compounds showed gastric ulcerogenic effect compared with reference nonsteroidal anti‐inflammatory drugs. Methyl 6‐(4‐(4‐fluorophenyl)piperazine)‐3(2H)‐pyridazinone‐2‐ylacetate 9e was found to be more active than acetylsalicylic acid (ASA). Methyl 6‐(4‐(2‐ethoxyphenyl)piperazine)‐3(2H)‐pyridazinone‐2‐ylacetate 9c has shown an anti‐inflammatory activity as compared to the standard compound indometacin at the carrageenan‐induced paw edema method.

A significant dependence of the anti‐inflammatory effect on the substituents has been observed. The pharmacological study of these compounds confirms that modification of the chemical group at the position 6 of the 3(2H)‐pyridazinone system influences analgesic and anti‐inflammatory activities. The structures of these new pyridazinone derivatives were confirmed by their IR and 1H‐NMR spectra and elemental analysis.
Formfindung und Entwurfsplanung des – Spinnaker Tower in Portsmouth
Authors: Andrä Hans Peter , Dietsch Burkhard , Sandner Dieter
Published: July 2004

Der Spinnaker Tower in Portsmouth wird derzeit im Rahmen der baulichen Neugestaltung des 12 ha großen Hafenbereichs, des “Gunwharf” (Bild 1), neben zahlreichen Büros, Einzelhandelsgeschäften, Freizeiteinrichtungen, Wohnungen und Parkplätzen als Aussichtsturm mit hohem gestalterischem und sinnbildlichem Anspruch gebaut. Da der ca. £ 23 Millionen teure Turm ursprünglich zur Feier der Jahrtausendwende fertiggestellt werden sollte, wird er zu einem Teil von der Stadt Portsmouth und zum anderen Teil von der britischen “Millennium Commission” finanziert.

Das Ingenieurbüro Leonhardt, Andrä und Partner (LAP) wurde 1997 vom Portsmouth City Council beauftragt, gemeinsam mit den Architekten HGP Greentree Alchurch Evans Limited diesen Aussichtsturm zu entwerfen, die Machbarkeit dieses Entwurfes anhand einer Entwurfsstatik zu gewährleisten und die Ausschreibungsunterlagen für die Realisierung des Projektes herzustellen.
Dimensionierung von Vakuumwasserhaltungen im tertiären Feinsand
Authors: Mayer Peter‐Michael , Schwab Christian , Voigt Thomas
Published: July 2004

Der Entwurf umfangreicher Vakuumwasserhaltungen ist aufgrund fehlender allgemeingültiger analytischer Berechnungsverfahren bisher auf Abschätzungen und Erfahrungen angewiesen. Vorliegende Untersuchungen zeigen exemplarisch für eine 80 m lange und 37 m breite Spundwandbaugrube im tertiären Feinsand, wie mittels räumlicher Finite‐Element‐Modelle die erforderliche Anzahl und Tiefe von Vakuumtiefbrunnen zur Grundwasserabsenkung berechnet werden kann. Die Auswirkungen von Schichtanisotropien bzw. lokaler Bereiche mit hoher Durchlässigkeit auf das erreichte Absenkziel und die geförderten Pumpmengen werden aufgezeigt. Darüberhinaus wird auch der Wasserdruck auf die Spundwand analysiert. Die Bedeutung zeitabhängiger Strömungsberechnungen wird durch die Verbindung von Aushub und Wasserhaltung deutlich und kann durch instationäre Betrachtungen erfaßt werden. Der Vergleich von in‐situ‐Messungen und Berechnungsergebnissen zeigt die Leistungsfähigkeit, aber auch die Grenzen numerischer Strömungsmodelle bei der Abschätzung des Ausführungsrisikos und möglicher wirtschaftlicher Optimierungen.
Stress im Boden: Früherkennung ökotoxikologischer Effekte durch Biomarker
Authors: Köhler Heinz‐R. , Triebskorn Rita
Published: July 2004

Bevor Kontaminationen von Böden mit Chemikalien ökosystemare Veränderungen nach sich ziehen, ist die Präsenz oder die Wirkung dieser Schadstoffe mittels Biomarkerreaktionen bei wirbellosen Bodentieren nachweisbar. Zu etablierten Biomarkern bei diesen Tieren zählen die Induktion von metallbindenden Proteinen und Stressproteinen sowie die lysosomale Stabilität und histo‐ beziehungweise cytopathologische Reaktionen. Unterschiedliche Sensitivitäten, Indikationsspektren und Konzentrations‐Wirkungs‐Kinetiken dieser subzellulären Marker erfordern eine Kombination derselben in einer “Biomarker‐Batterie” zur Frühdiagnostik auftretender Schäden. Molekulare und zelluläre Effektmarker gewährleisten, ähnlich wie in der Humanmedizin, verlässliche Aussagen über den Gesundheitszustand der untersuchten Organismen.
Ameisen: Kraftlose Einwanderer
Authors: Knoll Ulrike
Published: July 2004

Im Schlepptau von Ameisen treten viele Samen ihre Reise an, um sich abseits der Mutterpflanze zu entfalten ‐ in großer Entfernung haben sie die besten Überlebenschancen. Einwandernde Ameisenarten scheinen für diesen Kraftakt nicht ausgerüstet zu sein.
Morbus Crohn: Zweites krankheitsassoziiertes Gen entdeckt
Authors: Stoll Monika , Schreiber Stefan
Published: July 2004

Das Auftreten und der Verlauf von polygenetischen Krankheiten wie beispielsweise Asthma, Bluthochdruck oder Krebs wird durch genetische Faktoren, Umwelteinflüsse und Lebensgewohnheiten bestimmt. Die Identifikation von Genen, die am Ausbruch einer derartigen Krankheit beteiligt sind, galt noch vor wenigen Jahren als äußerst schwierig und wurde erst möglich, als ausreichend Informationen über genetische Variationen des menschlichen Genoms vorlagen. Einer der jüngsten Erfolge der Genomforschung ist die Entdeckung des zweiten krankheitsassoziierten Gens DLG5 (ein Homolog des Drosophila Disc‐Large Proteins) der chronisch entzündlichen Darmerkrankung (Morbus Crohn).
Mutationen in Mitochondrien verkürzen das Leben
Authors: Brennicke Axel
Published: July 2004

Ein Phänomen des Alterns ist die Zunahme an Mutationen in der zellulären DNA, insbesondere der DNA in den Mitochondrien. Bisher war unklar, ob diese phänotypische Beobachtung Ursache oder Wirkung ist. Aktuelle Forschungsergebnisse zeigen, dass eine erhöhte Mutationsrate in den Mitochondrien die vielen verschiedenen Merkmale des Alterungsprozesses zumindest bei Mäusen auslösen kann.
Artenschutz auf den Philippinen
Authors: Liebers Verena
Published: July 2004

Wirkungsvoller Artenschutz setzt Kenntnisse über Lebensweise und Interaktionen der Tier‐ und Pflanzenwelt voraus. Um die Vielfalt zu erhalten, sind vor allem Hot Spots der Biodiversität wie die Philippinen eine wichtige Quelle der Erkenntnis. Im Rahmen eines seit acht Jahren bestehenden philippinischen Artenschutzprojekts (PESCP) konnten jetzt wichtige Zusammenhänge zwischen Tieren und Pflanzenverbreitung bestätigt werden.
Die Chemie des Magnetsinns
Authors: Irsch Wilhelm
Published: July 2004

Zugvögel orientieren sich dank eines fein abgestimmten Magnetsinns, mit dem sie das Erdmagnetfeld zur Orientierung nutzen. Der innere Kompass von Zugvögeln kann die Achse Pol‐Äquator anzeigen, ohne den Nord‐ und den Südpol unterscheiden zu können. Damit scheint er auf einem anderen Prinzip zu beruhen als der technische, polare Magnetkompass.
Continuous infusion ofN-acetylcysteine reduces liver warm ischaemia–reperfusion injury
Authors: Glantzounis G K , Yang W , Koti R S , Mikhailidis D P , Seifalian A M , Davidson B R
Published: July 2004

Background

N-acetylcysteine (NAC) may modulate the initial phase (less than 2 h) of liver warm ischaemia–reperfusion (IR) injury but its effect on the late phase remains unclear. The present study investigated the role of NAC during the early and late phases in a rabbit lobar IR model.

Methods

Liver ischaemia was induced by inflow occlusion to the median and left liver lobes for 60 min, followed by 7 h of reperfusion. In the NAC group (n = 6), NAC was administered intravenously at 150 mg per kg over the 15 min before reperfusion and maintained at 10 mg per kg per h during reperfusion. In the IR group (n = 6), 20 ml 5 per cent dextrose was infused over the 15 min before reperfusion and continued at a rate of 10 ml/h. Animals in a sham operation group (n = 6) underwent laparotomy but no liver ischaemia. All animals were killed at the end of the experiment.

Results

Intracellular tissue oxygenation was improved after the second hour of reperfusion in animals treated with NAC compared with that in the IR group (P = 0·023). Hepatic microcirculation improved after 5 h of reperfusion (P = 0·036) and liver injury was reduced after 5 h, as indicated by alanine aminotransferase activity (P = 0·007) and indocyanine green clearance (uptake, P = 0·001; excretion, P = 0·032).

Conclusion

The main protective effect of NAC becomes apparent 5 h after hepatic ischaemic injury.
Synthesis of Phenanthrenes and Polycyclic Heteroarenes by Transition‐Metal Catalyzed Cycloisomerization Reactions
Authors: Mamane Victor , Hannen Peter , Fürstner Alois
Published: July 2004

Readily available biphenyl derivatives containing an alkyne unit at one of their ortho‐positions are converted into substituted phenanthrenes on exposure to catalytic amounts of either PtCl2, AuCl, AuCl3, GaCl3 or InCl3 in toluene. This 6‐endo‐dig cyclization likely proceeds through initial π‐complexation of the alkyne unit followed by interception of the resulting η2‐metal species by the adjacent arene ring. The reaction is inherently modular, allowing for substantial structural variations and for the incorporation of substituents at any site of the phenanthrene product. Moreover, it is readily extended to the heterocyclic series as exemplified by the preparation of benzoindoles, benzocarbazoles, naphthothiophenes, as well as bridgehead nitrogen heterocycles such as pyrrolo[1,2‐a]quinolines. Depending on the chosen catalyst, biaryls bearing halo‐alkyne units can either be converted into the corresponding 10‐halo‐phenanthrenes or into the isomeric 9‐halo‐phenanthrenes; in the latter case, the concomitant 1,2‐halide shift is best explained by assuming a metal vinylidene species as the reactive intermediate. The scope of this novel method for the preparation of polycyclic arenes is illustrated by the total synthesis of a series of polyoxygenated phenanthrenes that are close relatives of the anticancer agent combretastatin A‐4, as well as by the total synthesis of the aporphine alkaloid O‐methyl‐dehydroisopiline and its naturally occurring symmetrical dimer.
Palladium‐Catalyzed Electrophilic Allylation Reactions via Bis(allyl)palladium Complexes and Related Intermediates
Authors: Szabó Kálmán J.
Published: July 2004

The synthetic scope of the allyl–palladium chemistry can be extended to involve electrophilic reagents. The greatest challange in these reactions is the catalytic generation of an allyl–palladium intermediate incorporating a nucleophilic allyl moiety. A vast majority of the published reactions that involve palladium‐catalyzed allylation of electrophiles proceed via bis(allyl)palladium intermediates. The η1‐moiety of the bis(allyl)palladium intermediates reacts with electrophiles, including aldehydes, imines, or Michael acceptors. Recently, catalytic electrophilic allylations via mono‐allylpalladium complexes were also presented by employment of so‐called “pincer complex” catalysts.
Zerfallsverhalten von Partikeln in Wirbelschichten – Anwendung eines konstanten oberflächenbezogenen Abriebskoeffizienten
Authors: Rangelova J. , Mörl L. , Heinrich S. , Peters R.
Published: July 2004

No abstracts.
Experimentelle Untersuchung und Modellierung des Betriebsverhaltens eines Ultraschallreaktors zur akustisch‐thermischen Behandlung von Flüssigkeiten
Authors: Heinz V. , Zenker M.
Published: July 2004

No abstracts.
Vergleich von Turbulenzmodellen und Wandfunktionen zur numerischen Berechnung des turbulenten Wärmeübergangs in einer Rohrströmung
Authors: Michel H.
Published: July 2004

No abstracts.
Simulation der Hydrodynamik im Strahlwäscher
Authors: Loos T. , Mollekopf N.
Published: July 2004

No abstracts.
Aufbau und katalytische Aktivität hierarchisch nano‐strukturierter Oxid‐Katalysatoren – Teil 3: Einfluss der Calcinierungstemperatur auf Stabilität und katalytisches Verhalten geträgerter V2O5/TiO2‐Katalysatoren
Authors: Stelzer J. B. , Feldhoff A. , Caro J. , Fait M. , Habel D. , Feike E. , Schubert H.
Published: July 2004

No abstracts.
Standard‐Darstellung der Bruchfestigkeit verschiedener Festkörper in Abhängigkeit vom Partikeldurchmesser
Authors: Zlokarnik Marko
Published: July 2004

No abstracts.
ReadOpt – Reaktor‐Design‐ Optimierung durch Heuristik‐ gestützte MINLP‐Methoden
Authors: Till J. , Sand G. , Engell S. , von Trotha T. , Schembecker G.
Published: July 2004

No abstracts.
Die dritte Welle – Die Biotechnologie erobert die Chemieindustrie
Authors: Bachmann R. , Budde F. , Riese J.
Published: July 2004

Die Einsatzgebiete der Biotechnologie beschränken sich nicht länger nur auf die Pharmaindustrie und die Landwirtschaft. Auch die Chemieindustrie profitiert in zunehmendem Maße davon. Damit die Biotechnologie ihr Potenzial jedoch voll ausschöpfen kann, sind optimale Rahmenbedingungen nötig. Dies betrifft die Akzeptanz und Unterstützung seitens der Verbraucher, der Industrie und des Staates. Ohne ein günstiges Umfeld wird Deutschland bei dieser wichtigen Zukunftstechnologie gegenüber anderen Regionen der Welt das Nachsehen haben.
Produktdesign – Möglichkeiten der Produktgestaltung
Authors: Rähse W.
Published: July 2004

Die Entwicklung leistungsstarker, auf den Anwendungsfall zugeschnittener Chemieprodukte erfolgt einerseits über gezielte Veränderungen am Molekül (Product Engineering) und andererseits über zugesetzte Hilfsstoffe, Formulierungen oder Mischungen (Product Design). Das Produktdesign umfasst zusätzlich die optimierte Produkthandhabung und Gestaltung. Es wird für Feststoffe an den Beispielen der Granulierung und des Coatings erläutert sowie konkret für die Qualitätseinstellung in der Papierindustrie und für die Gestaltung von Teigwaren diskutiert. Aus Schmelzen lassen sich über die Extrusionstechnologie beliebige Formen realisieren, z. B. Folien, Stränge, Fasern, Hohl‐ bzw. Vollkörper (Flaschen, Rohre, Profile), oder über das Vertropfen/Versprühen entstehen Pulver, Granulate, Schuppen, Kügelchen und Pastillen. Für Flüssigkeiten erfolgt die Beschreibung der Einstellung gewünschter Produktleistungen am Beispiel der Niotenside, das Produktdesign am Beispiel der Milch und eines Öls. Die Kombination beider Produktdimensionen ist für die Lackindustrie dargestellt. Einige Gestaltungsmöglichkeiten von Suspensionen, Pasten und Lösungen werden an der Trocknung matrixverkapselter Enzyme, an der Zeolithherstellung sowie an der Verarbeitung keramischer Massen aufgezeigt.
Charakterisierung von Slurry‐ Fermentationsprozessen als Grundlage für die mathematische Modellierung
Authors: Kunz B. , Hempel K. , Glover K.
Published: July 2004

Die Kriterien zur Charakterisierung der klassischen Fermentationsprozesse Submers‐, Emers‐ und Solid‐State‐Fermentation reichen nicht aus, um alle Fermentationsarten hinreichend beschreiben zu können. Erste Ansätze der Etablierung der Slurry‐Fermentation als eigenständiges Fermentationsystem bedürfen jedoch der theoretischen Durchdringung. Dies erfolgt auf der Grundlage der Beschreibung der Slurry als disperses System und mittels der Stofftransport‐Charakterisierung. Die Slurry wird als zweiphasiges, monodisperses System aufgefasst, bei der die kontinuierliche Phase flüssig ist. Bedingt durch die hohe Suspensionsviskosität ist der konvektive Stofftransport einschränkt und geht gegen Null. Der Stofftransport ist jedoch bei einer Slurry sowohl durch Diffusion als auch durch Konvektion zu charakterisieren. Man unterscheidet drei Fälle der Slurry‐Fermentation: (1) niedriger Volumenbruch, hohe Suspensionsviskosität, diffusiver Stofftransport; (2) hoher Volumenbruch, hohe Suspensionsviskosität, diffusiver Stofftransport und (3) hoher Volumenbruch, hohe Suspensionsviskosität, mikrokonvektiver Stofftransport.
Doping und Dopinganalytik: Wirkstoffe und Methoden
Authors: Schänzer Wilhelm , Thevis Mario
Published: July 2004

Änderungen im Dopingreglement seit 1997 verbieten neben den klassischen Dopingsubstanzen der Stimulanzien, Narkotika, Anabolen Wirkstoffe, Diuretika und Peptidhormone weitere Substanzklassen wie Plasmaexpander, Antiestrogene, Aromatase‐Hemmer und künstliche Sauerstoffträger wie Perfluorkohlenwasserstoffe (PFCs) und quervernetzte Hämoglobine. Der Nachweis von Dopingsubstanzen, der wesentlich mit der GC‐MS‐Analytik geführt wurde und wird, bezieht zunehmend die LC‐MS‐ und LC‐MS/MS Analytik mitein. Damit werden Substanzen wie Beta‐Blocker, Diuretika, Corticosteroide und neuerdings auch Proteine wie Hemopure, ein querverneztes Hämoglobin, effektiv nachgewiesen. Der Nachweis von Erythropoeitin (EPO)‐Doping anhand einer Urinprobe gelingt mit der Methode der Isoelektrischen Fokussierung und Visualisierung charakteristischer EPO‐Banden mittels monoklonaler EPO‐Antikörper (Double Blotting).
Das geheime Leben der Pflanzenwurzeln: Liebigs Erben
Authors: Schubert Sven
Published: July 2004

Die Mineralstofftheorie ist die Grundlage der modernen Pflanzenernährung. Pflanzennährstoffe sind chemische Elemente, die für das Wachstum und die normale Entwicklung von Pflanzen notwendig sind. Sie werden zum Teil aus der Atmosphäre aufgenommen. Im Fall von molekularem Luftstickstoff müssen Pflanzen eine Symbiose mit bestimmten Bakterien eingehen, um diese Stickstoffform über den Prozess der N2‐Fixierung nutzen zu können. Hierzu werden spezielle Organe, die Knöllchen gebildet, die dem Schlüsselenzym, der Nitrogenase, die strukturellen Voraussetzungen bieten. Den überwiegenden Anteil der Nähstoffe eignet sich die Pflanze über das Wurzelsystem an. Da die Aufnahme gelöste Nährstoffe in der Bodenlösung voraussetzt, kommt der Mobilisierung von Nährstoffen eine besondere Bedeutung zu. Am Beispiel der Weißlupine, eine wichtige Modellpflanze in der aktuellen Forschung, werden wichtige Strategien zur Mobilisierung von Bodenphosphaten dargestellt.
Vultur‐ex durch Voltaren®
Authors: Jaenicke Lothar
Published: July 2004

Die Geiervögel (Vulturidae) sind zwar nach unserem Empfinden keine “schönen” Tiere, und auch ihre Lebensweise ist wenig appetitlich, aber sie gehören in den Kreislauf der Natur in zwingend notwendigem Maß. Sie sorgen dafür, dass gefallene Tiere und Aas so rasch wie möglich vom Boden verschwinden, die Umwelt nicht verpesten, sondern über den Kohlenstoff‐ und Stickstoff‐Stoffwechsel dieser Aasfresser wieder den assimilierenden Pflanzen und Mikroorganismen zugeführt werden.
Eine tragbare Wasserstoffquelle für Brennstoffzellen
Authors: Jaenicke Lothar
Published: July 2004

Brennstoffzellen mit Wasserstoff aus “Bio” sind ein Desiderat, groß‐ und kleinformatig für Motoren und Elektronik. Kandidaten für Biomasse sind Photosyntheseprodukte: Zucker, Stärke, Öle, Abfall von Pflanzen aller Art sowie deren Vergärungs‐ und Verarbeitungsprodukte, Ölmethylester und Ethanol.
Medical‐Monotoring – Ein neuer Trend im Chemie‐Schadensrecht
Authors: Börger Ulrich
Published: July 2004

Für Chemie‐Unternehmen in Europa ist die Auseinandersetzung mit der EU‐Kommission über die REACH‐Verordnung seit Jahren das bestimmende Thema. Pünktlich vor den anstehenden Beratungen des REACH‐Entwurfs im EU‐Parlament hat der World Wildlife Fund am 21. April 2004 in Brüssel die Ergebnisse einer Studie [1] veröffentlicht, wonach im Blut von 39 EU‐Abgeordneten 76 “iftige” Chemikalien aus industrieller Produktion nachgewiesen worden sein sollen.