bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of a superabsorbent polymer
Authors: Bakass M. , Bellat J. P. , Bertrand G.
Published: January 2007

We studied an amorphous polymer superabsorbent, able to absorb until 1000 times its weight of water. It is consisted of macromolecular chains, dependent between them by chemical bonds. The swelling of the product in the presence of water gives rise to a polyelectrolytic gel. The chemical analysis of polymer by energy dispersive spectrometry and photoelectrons spectroscopy with a microsounder X showed that the product is homogeneous. It contains carbon, oxygen, and sodium. The measurements of specific surface of the product show that the polymer is nonporous and present a weak surface of about 2.1 m2/g. The thermal study of polymer showed that, under the effect of the temperature and with atmospheric pressure, the polymer is degraded only at temperatures higher than 200°C and becomes porous. When the material is heated at higher temperature of 200°C, its surface becomes increasingly porous with also an increase in the size of the pores. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 782–786, 2007
Coloring effect of the organic hybrid of polyamide 6 and N,N′‐ethylene‐bis(tetrabromophthalimide)
Authors: Deng Xin , Dai Wen‐Li , Zheng Yun‐Long
Published: January 2007

Coloring study in organic hybrid of polyamide (PA6) and N,N′‐ethylene‐bis(tetrabromophthalimide) (EPT), where the chromophore was self‐assembled by hydrogen bonding formed between PA6 molecular chains and EPT compound, have been characterized by several techniques. CS930 double wavelength lamella scanner was employed to measure the change of color. The existence of hydrogen bonding in PA6/N‐N′‐ethylene‐bis (tetrabromophthalimide) (PA6EPT) was investigated with Fourier transform infrared (FTIR), the results of which were compared with that of PA6 with the same thermal history. FTIR spectra at room temperature revealed that there is essentially hydrogen bonding between PA6 and EPT. The crystallization behavior of PA6EPT affected by hydrogen bonding was studied by using FTIR. The temperature‐dependent behavior of both PA6 and PA6EPT was studied by temperature‐FTIR spectroscopy and differential scanning calorimetry (DSC). With temperature increasing, changes in sensitive, high‐resolution absorbance spectra are observed as dissolve‐volatilizing thin film. Temperature‐FTIR results showed that the hydrogen bonding in PA6EPT attenuated and dissociated considerably at a smaller rate than PA6, that is to say, hydrogen bonding in PA6EPT is more stable than that in PA6. DSC showed that the melting temperature of PA6EPT and PA6 are similar. However, the crystalline degree and crystalline temperature and melting enthalpy of PA6 and PA6EPT are different. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 594–600, 2007
Quantitative assessment of relationship between pressure performances and material mechanical properties of medical graduated compression stockings
Authors: Liu R. , Kwok Y. L. , Li Y. , Lao T. T. , Zhang X.
Published: January 2007

Graduated compression stockings (GCSs) have been widely applied for prophylaxis and treatment of venous disorders. Their pressure performances and medical functions depend largely upon the mechanical properties of stocking knitted fabrics. In the present study, the multiple fabric mechanical behaviors of GCSs with different pressure levels and medical functions were examined by using Kawabata standard evaluation system. On the basis of pressure ranges advised by the European Committee for Standardization, the definitive quantitative relationships between pressure performances and key mechanical properties of GCS fabrics were developed and evaluated. The results show that GCS fabrics with different pressure performances produced significant differences in tensile, shearing, and bending properties (P < 0.001). GCS fabrics generating lighter pressure possessed higher values in tensile strain, tensile energy at a given force, and lower values in shearing stiffness and bending rigidity, while stronger pressure levels are produced by the GCS fabrics with higher resistance to the mechanical deformations. Pressure magnitude performances of GCSs are an integrative action performed by multiple fabric mechanical properties. The developed relationships between pressure levels and material mechanical properties provide a rational and practical approach for assessing and predicting pressure functional performances of GCSs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 601–610, 2007
Characterization of nanoscale wool particles
Authors: Cheng Y. F. , Yuen C. W. M. , Li Y. , Ku S. K. A. , Kan C. W. , Hu J. Y.
Published: January 2007

Nanoscale wool particles were prepared from wool fibers by a special pretreatment with the aid of specially designed machinery and techniques. Scanning electron micrographs showed that the particle sizes of wool powders produced from wool fibers approximately 8–20 μm in diameter decreased from a microscale to a nanoscale after three stages of pulverization, which were further confirmed with a laser particle size analyzer. Fourier transmission infrared analysis showed that there were no substantial changes in the chemical structure of the wool after the pulverization processes. The wool powders after the second and third pulverizations slightly differed from that of the wool fiber and the particles after the first pulverization, with greater amounts of the secondary amine groups, amide groups, CS stretching vibrations, and OH bonds. X‐ray diffraction analysis showed that the crystallinity of the wool powders decreased when the particle sizes decreased, particularly at nanoscales. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 803–808, 2007
Morphology development in polypropylene/polystyrene blends during coalescence under shear
Authors: Li Yun‐Yan , Chen Zi‐Qi , Huang Yi , Sheng Jing
Published: January 2007

Morphology development during the coalescence under shear in polypropylene/polystyrene blends was studied in this article. The coalescence was performed by decreasing the shear rate after a fine morphology is obtained at higher shear rate. Time resolved SEM performance indicates that, because of the smaller capillary number, particles of the minor phase are almost spherical during the whole coalescence process. An original sizing method based on SEM is used to describe the time evolution of particle size and their distribution. Initially, the volume–average particle size increases rapidly and levels off before a steady state is obtained, while the number–average particle size increases slowly but monotonously during the whole coalescence process. This two‐step increase in volume average particle size is discussed in terms of coalescence efficiency. Further, an examination of scaling behavior shows that a master curve for particle growth with different compositions is observed by plotting the relative increase in particles size versus the shear strain, confirming that the evolution of particle size could be described by a scaling law. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 666–671, 2007
Plasticized/graphite reinforced phenolic resin composites and their application potential
Authors: El‐Tantawy Farid
Published: January 2007

Plasticized graphite (PG)/phenolic resin composites are candidates for positive temperature coefficient resistivity (PTCρ) thermistors, which are used for self‐recoverable elements that provide protection from overcurrents, gasoline sensors, and electrostatic charge and electromagnetic wave shielding in many kinds of electrical devices. The morphology and network structure of PG/phenolic resin composites have been characterized with scanning electron microscopy and with measurements of the crosslinking density, bound resin content, degree of crystallinity, viscosity, surface energy, thermal conductivity, enthalpy, and glass‐transition temperature. In addition, mechanical properties such as the tensile strength, Young's modulus, Shore A hardness, and elongation at break for resins filled with PG have been studied. The electrical properties of the composites have been measured to relate the PG volume fraction to the electrical conductivity. A large PTCρ value has been observed for all samples. The mechanism of the PTCρ effect in the materials is related to the thermal expansion and highest barrier energy of the composites. Switching behaviors of the current and voltage for all samples have been observed. The applicability of PG/phenolic resin composites for temperature controllers and gasoline gas sensors has been examined. The antistatic charge dissipation and dielectric constant as functions of the PG content have been studied. Finally, the experimental electromagnetic interference of the PG/phenolic composites has been investigated in the frequency range of 1–15 GHz and compared with a theoretical model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 697–709, 2007
Acid wash in determining cellular uptake of Fab/cell‐permeating peptide conjugates
Authors: Kameyama Shouju , Horie Mayo , Kikuchi Takeo , Omura Takao , Tadokoro Akiko , Takeuchi Toshihide , Nakase Ikuhiko , Sugiura Yukio , Futaki Shiroh
Published: January 2007

Successful intracellular delivery of various bioactive molecules has been reported using cell‐permeating peptides (CPPs) as delivery vectors. To determine the effects of CPPs on the cellular uptake of immunoglobulin Fab fragment, conjugates of a radio‐iodinated Fab fragment with CPPs (CPP‐125I‐Fab) derived from HIV‐1 TAT, HIV‐1 REV, and Antennapedia (ANP) were prepared. These vectors are rich in basic amino acids, and their strong adsorption on cell surfaces often results in overestimation of internalized peptides. Cell wash with an acidic buffer (0.2M glycine–0.15M NaCl, pH 3.0) was thus employed in this study to remove cell‐surface adsorbed CPP‐125I‐Fab conjugates. This procedure enabled clearer understanding of the methods of internalization of CPP‐125I‐Fab conjugates. The kinetics of internalization of REV‐125I‐Fab conjugate was rapid, and a considerable fraction of REV‐125I‐Fab was taken up by HeLa cells as early as 5 min after administration. It was also shown that cellular uptake of these conjugates was significantly inhibited in the presence of endocytosis/ macropinocytosis inhibitors, in the order REV‐125I‐Fab ≥ TAT‐125I‐Fab ≥ ANP‐125I‐Fab; this order was the same as for effectiveness of intracellular delivery. Simultaneous cell washing with phosphate‐buffered saline (PBS) and this acidic buffer effectively separated the internalized conjugates from the cell‐surface‐adsorbed ones, and considerable differences were observed in these amounts dependent on the employed CPPs. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 98–107, 2007.

This article was originally published online as an accepted preprint. The ‘Published Online’ date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Structural flexibility of the nucleosome core particle at atomic resolution studied by molecular dynamics simulation
Authors: Roccatano Danilo , Barthel Andre , Zacharias Martin
Published: January 2007

Comparative explicit solvent molecular dynamics (MD) simulations have been performed on a complete nucleosome core particle with and without N‐terminal histone tails for more than 20 ns. Main purpose of the simulations was to study the dynamics of mobile elements such as histone N‐terminal tails and how packing and DNA‐bending influences the fine structure and dynamics of DNA. Except for the tails, histone and DNA molecules stayed on average close to the crystallographic start structure supporting the quality of the current force field approach. Despite the packing strain, no increase of transitions to noncanonical nucleic acid backbone conformations compared to regular B‐DNA was observed. The pattern of kinks and bends along the DNA remained close to the experiment overall. In addition to the local dynamics, the simulations allowed the analysis of the superhelical mobility indicating a limited relative mobility of DNA segments separated by one superhelical turn (mean relative displacement of approximately ±0.2 nm, mainly along the superhelical axis). An even higher rigidity was found for relative motions (distance fluctuations) of segments separated by half a superhelical turn (approximately ±0.1 nm). The N‐terminal tails underwent dramatic conformational rearrangements on the nanosecond time scale toward partially and transiently wrapped states around the DNA. Many of the histone tail changes corresponded to coupled association and folding events from fully solvent‐exposed states toward complexes with the major and minor grooves of DNA. The simulations indicate that the rapid conformational changes of the tails can modulate the DNA accessibility within a few nanoseconds. © 2007 Wiley Periodicals, Inc. Biopolymers 85: 407–421, 2007.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Impact of an extruded nucleotide on cleavage activity and dynamic catalytic core conformation of the hepatitis delta virus ribozyme
Authors: Sefcikova Jana , Krasovska Maryna V. , Špačková Nad'a , Šponer Jiří , Walter Nils G.
Published: January 2007

The self‐cleaving hepatitis delta virus (HDV) ribozyme is essential for the replication of HDV, a liver disease causing pathogen in humans. The catalytically critical nucleotide C75 of the ribozyme is buttressed by a trefoil turn pivoting around an extruded G76. In all available crystal structures, the conformation of G76 is restricted by stacking with G76 of a neighboring molecule. To test whether this crystal contact introduces a structural perturbation into the catalytic core, we have analyzed ∼200 ns of molecular dynamics (MD) simulations. In the absence of crystal packing, the simulated G76 fluctuates between several conformations, including one wherein G76 establishes a perpendicular base quadruplet in the major groove of the adjacent P1 stem. Second‐site mutagenesis experiments suggest that the identity of the nucleotide in position 76 (N76) indeed contributes to the catalytic activity of a trans‐acting HDV ribozyme through its capacity for hydrogen bonding with P1. By contrast, in the cis‐cleaving genomic ribozyme the functional relevance of N76 is less pronounced and not correlated with the P1 sequence. Terbium(III) footprinting and additional MD show that the activity differences between N76 mutants of this ribozyme are related instead to changes in average conformation and modified cross‐correlations in the trefoil turn. © 2007 Wiley Periodicals, Inc. Biopolymers 85: 392–406, 2007.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
A method for three‐dimensional protein characterization and its application to a complex plant (corn) extract
Authors: Gu Zhengrong , Glatz Charles E.
Published: January 2007

Knowledge of host protein properties is critical for developing purification methods for recombinant proteins from a specific host, or for choosing suitable hosts and targeted expression tissues for a specific recombinant protein. A method to obtain a three‐dimensional (3D) map (surface hydrophobicity (SH), isoelectric point (pI), and molecular weight (MW)), of a host's aqueous soluble protein properties was developed. The method consists of hydrophobic partitioning in a PEG 3350 (15.7%)‐Na2SO4 (8.9%)‐NaCl (3%) aqueous two‐phase (ATP) system followed by quantitative, 2D‐electrophoretic characterization of the proteins of each equilibrium phase and the original extract. The pI and MW of host proteins were obtained directly through 2D electrophoresis. The partition coefficients of individual proteins were obtained by quantitative matching of protein spots in the top and bottom phase gels and calculating the protein partition coefficients from this information. Correlation of the partition coefficient to a SH scale was established by partitioning several model proteins with known surface hydrophobicities in the same ATP system. The inclusion of the extract gel provided for a spot selection criterion based on satisfactory mass balance closure. The method is illustrated by application to a mixture of model proteins and to complex mixtures, that is, corn germ proteins extracted at pH 7 and pH 4. Biotechnol. Bioeng. 2007; 97: 1158–1169. © 2007 Wiley Periodicals, Inc.
Understanding signaling in yeast: Insights from network analysis
Authors: Arga K Yalçın , Önsan Z İlsen , Kırdar Betül , Ülgen Kutlu Ö , Nielsen Jens
Published: January 2007

Reconstruction of protein interaction networks that represent groups of proteins contributing to the same cellular function is a key step towards quantitative studies of signal transduction pathways. Here we present a novel approach to reconstruct a highly correlated protein interaction network and to identify previously unknown components of a signaling pathway through integration of protein–protein interaction data, gene expression data, and Gene Ontology annotations. A novel algorithm is designed to reconstruct a highly correlated protein interaction network which is composed of the candidate proteins for signal transduction mechanisms in yeast Saccharomyces cerevisiae. The high efficiency of the reconstruction process is proved by a Receiver Operating Characteristic curve analysis. Identification and scoring of the possible linear pathways enables reconstruction of specific sub‐networks for glucose‐induction signaling and high osmolarity MAPK signaling in S. cerevisiae. All of the known components of these pathways are identified together with several new “candidate” proteins, indicating the successful reconstructions of two model pathways involved in S. cerevisiae. The integrated approach is hence shown useful for (i) prediction of new signaling pathways, (ii) identification of unknown members of documented pathways, and (iii) identification of network modules consisting of a group of related components that often incorporate the same functional mechanism. Biotechnol. Bioeng. 2007; 97: 1246–1258. © 2007 Wiley Periodicals, Inc.
Mesophilic and thermophilic biotreatment of BTEX‐polluted air in reactors
Authors: Mohammad Balsam T. , Veiga María C. , Kennes Christian
Published: January 2007

This study compares the removal of a mixture of benzene, toluene, ethylbenzene, and all three xylene isomers (BTEX) in mesophilic and thermophilic (50°C) bioreactors. In the mesophilic reactor fungi became dominant after long‐term operation, while bacteria dominated in the thermophilic unit. Microbial acclimation was achieved by exposing the biofilters to initial BTEX loads of 2–15 g m−3 h−1, at an empty bed residence time of 96 s. After adaptation, the elimination capacities ranged from 3 to 188 g m−3 h−1, depending on the inlet load, for the mesophilic biofilter with removal efficiencies reaching 96%. On the other hand, in the thermophilic reactor the average removal efficiency was 83% with a maximum elimination capacity of 218 g m−3 h−1. There was a clear positive relationship between temperature gradients as well as CO2 production and elimination capacities across the biofilters. The gas phase was sampled at different depths along the reactors observing that the percentage pollutant removal in each section was strongly dependant on the load applied. The fate of individual alkylbenzene compounds was checked, showing the unusually high biodegradation rate of benzene at high loads under thermophilic conditions (100%) compared to its very low removal in the mesophilic reactor at such load (<10%). Such difference was less pronounced for the other pollutants. After 210 days of operation, the dry biomass content for the mesophilic and thermophilic reactors were 0.300 and 0.114 g g−1support, respectively, reaching higher removals under thermophilic conditions with a lower biomass accumulation, that is, lower pressure drop. Biotechnol. Bioeng. 2007;97:1423–1438. © 2007 Wiley Periodicals, Inc.
Submerged monoxenic culture of the entomopathogenic nematode Steinernema carpocapsae in an internal‐loop airlift bioreactor using two configurations of the inner tube
Authors: Chavarría‐Hernández Norberto , Sanjuan‐Galindo René , Rodríguez‐Pastrana Blanca‐Rosa , Medina‐Torres Luis , Rodríguez‐Hernández Adriana‐Inés
Published: January 2007

This article reports the submerged culture of the entomopathogenic nematode Steinernema carpocapsae and its symbiotic bacterium, Xenorhabdus nematophila, within an internal‐loop airlift bioreactor. Two configurations of the inner cylinder were tested: a standard draft tube (SDT) and a static mixer (SM), as well as two production media: MP1 (500 mL/L whey, among other ingredients) and MP2 (82 mL/L agave‐juice from Agave spp., among other ingredients). Three fermentations were carried out: F1 → SDT‐MP1, F2 → SM‐MP1 and F3 → SM‐MP2. The operating conditions were expressed on the basis of dimensionless Reynolds number (Re) and volumetric oxygen transfer coefficient (kLa), both of them determined on riser and downcomer sections within the bioreactor. The experiments began with fewer than 1,000 infective juvenile nematode stages (IJ) per mL and at t = 20 d, they achieved (nematodes/mL‐%IJ) 222,000‐87%, 62,200‐23% and 114,600‐80%, within F1, F2 and F3 experiments, respectively. Nonetheless, the achieved maximum nematode biomass concentrations (g/L) were F1 → 408, F2 → 557 and F3 → 613, and occurred at t = 16, 10 and 12 d, respectively. The fermentation operating conditions involved 0.042 (−) < Re < 647 (−) and 2.8× 10−4 s−1 < kLa < 0.0447 s−1, as functions of 0.004 m/s < superficial gas velocity (within the riser) < 0.079 m/s, 0.001 m/s < mean downcomer velocity < 0.014 m/s, and culture broth rheological properties which evolved from nearly the Newtonian behaviour to the pseudoplastic one. The maximum IJ concentration was achieved within F1 experiment (193,406 IJ/mL). Also, fermentation conditions involving higher riser‐Re and lower downcomer‐Re as well as higher nutriment concentrations in culture medium, promote higher nematode biomass concentrations but lower %IJ, maybe as a result of better conditions for the nematode population development. Biotechnol. Bioeng. 2007; 98: 167–176. © 2007 Wiley Periodicals, Inc.
Coronary septal collaterals as an access for the retrograde approach in the percutaneous treatment of coronary chronic total occlusions
Authors: Surmely Jean‐François , Katoh Osamu , Tsuchikane Etsuo , Nasu Kenya , Suzuki Takahiko
Published: January 2007

Objectives: To investigate the feasibility and safety of the percutaneous dilatation of coronary septal collaterals and to allow its use as an access for retrograde approach to percutaneous coronary intervention (PCI) of coronary chronic total occlusions (CTOs). Background: Despite improvements in percutaneous techniques and materials, CTO recanalization success rate is still suboptimal. The retrograde approach allows to significantly increase this success rate. However, its application via a bypass graft or epicardial collateral can potentially result in severe complications. A safer retrograde access is desired and would allow broadening the application of the retrograde approach in the percutaneous treatment of CTOs. Methods: After a failed antegrade CTO recanalization attempt, a retrograde approach via septal collaterals was tried in 21 patients (19 males, 2 females). The septal collateral was accessed via the contralateral patent coronary artery and was crossed with a hydrophilic floppy wire. After successful wire crossing of the septal collateral, sequential low pressure dilatation was performed with a 1.25 or 1.5 mm balloon to allow the delivery of a balloon catheter up to the distal CTO site. Results: Successful wire crossing and balloon dilatation of septal collaterals was achieved in 19 cases and in 17 cases, respectively. Postdilatation septal collateral diameter increased significantly reaching a mean diameter of 1.46 ± 0.38 mm. Retrograde CTO recanalization was successfully performed in 71% of the cases. No major complications occurred. Conclusions: Coronary septal collaterals can be used as an access for the retrograde approach in the percutaneous treatment of CTOs. © 2007 Wiley‐Liss, Inc.
Patent foramen ovale closure: A new therapy for migraine
Authors: Schwerzmann Markus , Nedeltchev Krassen , Meier Bernhard
Published: January 2007

Migraine is a recurrent disabling disorder predominantly affecting middle‐aged women. Migraine occurs with or without aura symptoms. Several studies have shown an increased prevalence of right‐to‐left shunts (RLSs) in migraine with aura. The overwhelming majority of these shunts were due to a patent foramen ovale (PFO). Furthermore, migraine with aura is more prevalent in clinical entities associated with a RLS, e.g. cryptogenic stroke, decompression illness in divers, or in patients with hereditary hemorrhagic teleangiectasia and pulmonary arteriovenous fistulas. Retrospective studies have consistently shown that shunt closure was associated with a significant reduction in migraine frequency. Its beneficial effect seemed to exceed the efficacy of conventional migraine therapy. Several randomized clinical trials to prospectively assess the benefit of shunt closure in migraine patients have been initiated. The only one completed, the MIST trial (Migraine Intervention with STARFLEX Technology), showed a significant reduction of migraine with aura after device implantation, compared with controls. However, the benefit of PFO closure was more modest than expected. This review recapitulates the current data regarding PFO closure and migraine with aura and summarizes in brief the current knowledge regarding migraine pathophysiology and the link to a RLS. © 2006 Wiley‐Liss, Inc.
New Predictive Correlations for the Drop Size in a Rotating Disc Contactor Liquid‐Liquid Extraction Column
Authors: Ismail Al‐Rahawi A. M.
Published: January 2007

Sauter mean drop sizes (d32) generated from a hole distributor in liquid extraction RDC columns were studied under various conditions. Experiments were designed to generate data required to determine the main variables that control the drop sizes in RDCs. Two precise correlations were proposed for predicting d32 in a RDC extraction column. The first was based on operating variables, hole‐distributor diameter, disc speed, column geometry, and system physical properties. The second one considered the same variables, except the column geometry. This model can be used for design purposes. The two correlations are the first of their type to consider the distributor hole inlet diameter in a RDC column. This diameter has been neglected by previous investigators. The maximum standard deviation for all data is 0.75 %, with a maximum absolute error of 6.8 %.
Leuchtdioden in der Chemie – Eine Hochzeit verschiedener Technologien
Authors: Kreisel G. , Meyer S. , Tietze D. , Fidler T. , Gorges R. , Kirsch A. , Schäfer B. , Rau S.
Published: January 2007

Die Miniaturisierung von Reaktoren hat eine bemerkenswerte Eigendynamik entwickelt. Die Schwierigkeit besteht dabei oft darin, in das Konzept analytische Komponenten oder Einrichtungen zum Energieeintrag etc. zu integrieren. Für den Fall der Photomikrostrukturreaktoren ist es nun gelungen, Leuchtdioden (LEDs) als Lichtquellen mit dieser Reaktortechnik zu kombinieren. Darüber hinaus wird die Eignung von LEDs als monochromatische Lichtquelle im chemischen Labor gezeigt.
Modellierung und experimentelle Untersuchung der Wirbelschicht‐Sprühgranulation im überhitzen Wasserdampf
Authors: Hampel R. , Peglow M. , Heinrich S. , Mörl L.
Published: January 2007

Die Wirbelschichttechnik bietet die Möglichkeit, feindisperse Produkte durch Granulation in grobkörnige Produkte umzuwandeln und diesen dadurch veränderte Partikeleigenschaften aufzuprägen. Die Wirbelschicht‐Sprühgranulation in Luft wird in vielen Bereichen der Industrie angewendet. Die Verwendung von Dampf als Fluidisationsmedium hat demgegenüber für bestimmte Stoffsysteme Vorteile. Der Prozess der Granulation im überhitzten Wasserdampf wird in diesem Beitrag theoretisch und experimentell untersucht.
Implications of Molecular Orbital Symmetries and Energies for the Electron Delocalization of Inorganic Clusters
Authors: Corminboeuf Clémence , King R. Bruce , Schleyer Paul von Rague
Published: January 2007

Isostructural clusters exhibit contrasting magnetic properties when the number of electrons differs. Surprisingly, the same is true even for isoelectronic cages (e.g. Oh B6H62− is diatropic, whereas Oh Si62− is paratropic) or for those with different substitutents (e.g. Td B4H4 is paratropic, whereas Td B4F4 is diatropic). Indeed, the total nucleus‐independent chemical shift (NICS) values, based on shieldings computed at cluster centers, may range considerably in magnitude and even change from diatropic (up‐field shifted) to paratropic (down‐field shifted). Similarly, individual dissected canonical molecular orbital contributions to the total NICS values computed at the “gauge‐including atomic orbitals” (GIAO) level vary greatly. This contrasting behavior arises from molecular orbital energy differences, from the extent of orbital overlap, as well as from symmetry‐based selection rules derived from group theory. Differences in magnetic properties may originate from the symmetry of the orbitals; specifically from the forbidden nature of the highest occupied molecular orbital→lowest unoccupied molecular orbital (HOMO→LUMO) electronic excitation weighted by the occupied‐unoccupied orbital energy difference. Thus, HOMO‐NICS values are generally highly paratropic if the HOMO→LUMO rotational transition is allowed by symmetry selection rules.
Discontinuous fragmentation of nuclear DNA during apoptosis revealed by discrete “sub‐G1” peaks on DNA content histograms
Authors: Kajstura Malgorzata , Halicka H. Dorota , Pryjma Juliusz , Darzynkiewicz Zbigniew
Published: January 2007

Background:

Internucleosomal DNA fragmentation is one of the hallmarks of apoptosis. Because the low molecular weight DNA fragments are extracted during cell staining in aqueous solutions, apoptotic cells can be identified on DNA content frequency histograms as cells with fractional (“sub‐G1”) DNA content. The aim of the present study was to explore whether in situ DNA fragmentation during apoptosis is discontinuous or progresses incessantly and if it is discontinuous, to define the resistant to cleavage fraction of DNA that remains stainable with the fluorochrome.

Materials and Methods:

The model of activation‐induced apoptosis of human lymphocytes was chosen as it provides uniform cell population with identical DNA content (DI = 1.00) that undergo apoptosis. Their apoptosis was induced by multivalent mitogen phytohemagglutinin (PHA) in the absence and presence of geldanamycin (GA), the benzoquinone ansamycin antibiotic which binds to Hsp90 (Heat Shock Protein 90) and alters its function. The cells were stained with acridine orange, the metachromatic fluorochrome that differentially stains cellular DNA and RNA.

Results:

A sharp, discrete peak representing the subpopulation of “sub‐G1” cells with highly reproducible DI = 0.42 ± 0.02 (CV = 5.5 ± 1.2) was observed on DNA content histograms of lymphocytes whose apoptosis was induced by PHA alone. Two distinct peaks, one representing cell subpopulations with DI = 0.42 (as above) and another, with DI = 0.79 ± 0.04 (CV = 5.8 ± 0.4), respectively, were seen in apoptotic cells from cultures stimulated with PHA in the presence of GA. The frequency of cells represented by the sub‐G1 peaks varied depending on time of induction of apoptosis and GA concentration.

Conclusions:

Apoptosis‐induced DNA fragmentation is discontinuous; approximately 42% of DNA is relatively stable and remains within the cell. The data suggest that the stable DNA is associated with nuclear matrix while the degradable fraction represents DNA in loop domains. A transient DNA stabilization is apparent in the presence of GA as evidenced by the presence of cell subpopulations with 79% of DNA retained in the cell. The observed discontinuity of DNA fragmentation appears to reflect sequential involvement of different nucleases and may also be modulated by chromatin structure. © 2007 International Society for Analytical Cytology.
Greater hippocampal neuronal recruitment in food‐storing than in non‐food‐storing birds
Authors: Hoshooley Jennifer S. , Sherry David F.
Published: January 2007

Previous research has shown heightened recruitment of new neurons to the chickadee hippocampus in the fall. The present study was conducted to determine whether heightened fall recruitment is associated with the seasonal onset of food‐storing by comparing neurogenesis in chickadees and a non‐food‐storing species, the house sparrow. Chickadees and house sparrows were captured in the wild in fall and spring and received multiple injections of the cell birth marker bromodeoxyuridine (BrdU). Birds were held in captivity and the level of hippocampal neuron recruitment was assessed after 6 weeks. Chickadees showed significantly more hippocampal neuronal recruitment than house sparrows. We found no seasonal differences in hippocampal neuronal recruitment in either species. In chickadees and in house sparrows, one‐third of new cells labeled for BrdU also expressed the mature neuronal protein, NeuN. In a region adjacent to the hippocampus, the hyperpallium apicale, we observed no significant differences in neuronal recruitment between species or between seasons. Hippocampal volume and total neuron number both were greater in spring than in fall in chickadees, but no seasonal differences were observed in house sparrows. Enhanced neuronal recruitment in the hippocampus of food‐storing chickadees suggests a degree of neurogenic specialization that may be associated with the spatial memory requirements of food‐storing behavior. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007.
Cyclic fatty acids in sunflower oils during frying of frozen foods with oil replenishment
Authors: Romero Antonio , Bastida Sara , Sánchez‐Muniz Francisco J.
Published: January 2007

Frying of frozen foods has become popular because it considerably reduces cooking time. Polymers and cyclic fatty acid monomers (CFAM) formed during frying are potentially toxic and therefore their production should be minimized. Twenty discontinuous fryings of different frozen foods were carried out over ten consecutive days, in sunflower oil (SO) and in high‐oleic acid sunflower oil (HOSO), by adding fresh oil after each frying to bring the volume of the fryer oil back to 3 L. CFAM methyl ester derivates were hydrogenated, isolated, concentrated and quantified by HPLC using a reverse‐phase column, followed by gas chromatography. After 20 fryings, significantly higher contents of polar material, polymers and CFAM (all p <0.001) were found in SO than in HOSO. Bicyclic compound formation was four times higher in SO (p <0.001). The fat from the fried potatoes presented a polymer content very similar to that of their corresponding oils. The 100‐g rations of the SO‐fried potatoes from the 20th frying supply 49 or 15%, respectively, more polymers and CFAM and 1 mg more bicyclic fatty acids than the 100‐g rations of HOSO‐fried potatoes. Because digestion and absorption of polar material, polymers and CFAM occur, the data clearly show the advantageousness and advisability of frying with HOSO rather than SO.
Conformational Analysis of MαNP Esters, Powerful Chiral Resolution and 1H NMR Anisotropy Tools – Aromatic Geometry and Solvent Effects on Δδ Values
Authors: Kasai Yusuke , Sugio Akinori , Sekiguchi Satoshi , Kuwahara Shunsuke , Matsumoto Takatoshi , Watanabe Masataka , Ichikawa Akio , Harada Nobuyuki
Published: January 2007

The MαNP acid method is very powerful for the preparation of enantiopure alcohols by resolution and the simultaneous determination of their absolute configurations by the 1H NMR anisotropy effect, where the syn‐syn conformation is taken as the preferred conformation of MαNP esters. However, the syn‐syn conformation of MαNP esters looks unstable, because two electronegative oxygen atoms (CH3O and C=O) are close to each other. To solve the problem of why the MαNP esters take such a syn‐syn conformation, the aromatic geometry and solvent effects on the 1H NMR anisotropy data were studied, leading to the following conclusions: i) the hydrogen‐bonding‐like interaction among the H‐8′ of the naphthyl group, the ester carbonyl oxygen, and the methoxy oxygen supports a triangular intramolecular force to stabilize the syn‐syn conformation; ii) triangular hydrogen bonding among a hydrogen atom of protic solvents, the ester carbonyl oxygen, and the methoxy oxygen also supports the syn‐syn conformation. This hydrogen bonding, as the solvation effect implies, suggests that a similar hydrogen bonding between a MαNP ester and a hydroxy group of the silica gel surface would make a dominant contribution to the excellent discrimination of diastereomeric MαNP esters observed in the HPLC on silica gel.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
A Carbocyclic Analog of the Oxidatively Generated DNA Lesion Spiroiminodihydantoin
Authors: Müller Heiko , Carell Thomas
Published: January 2007

8‐Oxo‐7,8‐dihydro‐2′‐deoxyguanosine (8‐oxo‐dG) is a mutagenic DNA lesion which is prone to further oxidation. One‐electron oxidants like IrIV oxidize 8‐oxo‐dG to give secondary lesions such as the spiroiminodihydantoin. This lesion blocks DNA polymerases and induces G → T as well as G → C transversions. Here, we report the synthesis of a carbocyclic analog of the 8‐oxo‐dG lesion and the carbocyclic version of the spiroiminodihydantoin lesion. Both lesion analogs were obtained within single‐stranded DNA and as their corresponding nucleosides. Characterization of the lesion analogs was achieved by HPLC, ESI‐MS and ESI‐MS/MS, as well as enzymatic digestion of the oligonucleotides. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Dual‐opposite‐injection CZE: Theoretical aspects and application to organic and pharmaceutical compounds
Authors: Weekley Brian S. , Foley Joe P.
Published: January 2007

Several important figures of merit (migration time, efficiency, resolution, resolution per unit time, and electrophoretic selectivity) are quantitatively compared for the first time for conventional CZE and dual‐opposite‐injection CZE (DOI‐CZE). Aspects of DOI‐CZE relevant to the separation of organic and pharmaceutical ions (MW>120 Da) are also discussed. Two new approaches to resolve the codetection of anions and cations, hydrodynamic flow‐modified DOI‐CZE and polarity reversal in combination with asymmetric detector window positioning, are compared with the method of preliminary transport, a variable procedure within sequential sample introduction, using a six‐component sample of organic and pharmaceutical compounds. The advantages of DOI‐CZE for the simultaneous analysis of organic/pharmaceutical anions and cations are illustrated in a direct comparison of conventional CZE and DOI‐CZE for the separation of a ten‐component mixture of pharmaceutical ions (five ionized acids and five ionized bases).
Fluid dynamics in capillary and chip electrochromatography
Authors: Nischang Ivo , Tallarek Ulrich
Published: January 2007

This review is concerned with the phenomenological fluid dynamics in capillary and chip electrochromatography (EC) using high‐surface‐area random porous media as stationary phases. Specifically, the pore space morphology of packed beds and monoliths is analyzed with respect to the nonuniformity of local and macroscopic EOF, as well as the achievable separation efficiency. It is first pointed out that the pore‐level velocity profile of EOF through packed beds and monoliths is generally nonuniform. This contrasts with the plug‐like EOF profile in a single homogeneous channel and is caused by a nonuniform distribution of the local electrical field strength in porous media due to the continuously converging and diverging pores. Wall effects of geometrical and electrokinetic nature form another origin for EOF nonuniformities in packed beds which are caused by packing hard particles against a hard wall with different zeta potential. The influence of the resulting, systematic porosity fluctuations close to the confining wall over a distance of a few particle diameters becomes aggravated at low column‐to‐particle diameter ratio. Due to the hierarchical structure of the pore space in packed beds and silica‐based monoliths which are characterized by discrete intraparticle (intraskeleton) mesoporous and interparticle (interskeleton) macroporous spatial domains, charge‐selective transport prevails within the porous particles and the monolith skeleton under most general conditions. It forms the basis for electrical field‐induced concentration polarization (CP). Simultaneously, a finite and – depending on morphology – often significant perfusive EOF is realized in these hierarchically structured materials. The data collected in this review show that the existence of CP and its relative intensity compared to perfusive EOF form fundamental ingredients which tune the fluid dynamics in EC employing monoliths and packed beds as stationary phases. This addresses the (electro)hydrodynamics, associated hydrodynamic dispersion, as well as the migration and retention of charged analytes.
Modelling of fluid–structure interactions with the space–time finite elements: Solution techniques
Authors: Tezduyar Tayfun E. , Sathe Sunil
Published: January 2007

The space–time fluid–structure interaction (FSI) techniques developed by the Team for Advanced Flow Simulation and Modeling (T★AFSM) have been applied to a wide range of 3D computation of FSI problems, some as early as in 1994 and many with challenging complexities. In this paper, we review these space–time FSI techniques and describe the enhancements introduced recently by the T★AFSM to increase the scope, accuracy, robustness and efficiency of these techniques. The aspects of the FSI solution process enhanced include the deforming‐spatial‐domain/stabilized space–time (DSD/SST) formulation, the fluid–structure interface conditions, the preconditioning techniques used in iterative solution of the linear equation systems, and a contact algorithm protecting the quality of the fluid mechanics mesh between the structural surfaces coming into contact. We present a number of 3D numerical examples computed with these new stabilized space–time FSI (SSTFSI) techniques. Copyright © 2007 John Wiley & Sons, Ltd.
Association of CD44 V3‐containing isoforms with tumor cell growth, migration, matrix metalloproteinase expression, and lymph node metastasis in head and neck cancer
Authors: Wang Steven J. , Wreesmann Volkert B. , Bourguignon Lilly Y. W.
Published: January 2007

Background.

The CD44 family of receptors includes multiple variant isoforms, some of which have been linked to tumor progression. The objective of this study was to investigate whether CD44 v3‐containing isoforms are involved in head and neck squamous cell carcinoma (HNSCC) tumor progression.

Methods.

Laboratory investigation utilizing HNSCC cell lines and clinical tissue specimens was performed.

Results.

Investigation of 13 HNSCC cell lines revealed a diversity of CD44 isoform profiles, including expression of CD44 v3‐containing isoforms. Two cell lines, HOC313 and MDA1483, were selected for further study based on their CD44 v3 expression profile. The HOC313 cell line, which highly expresses CD44 v3‐containing isoforms, demonstrated hyaluronan‐mediated CD44‐dependent promotion of tumor cell growth and migration. Conditioned media from the HOC313 cell line also exhibited high matrix metalloproteinase expression on gelatin zymography. Immunohistochemical analysis of a series of metastatic HNSCC lymph nodes revealed CD44 overexpression as well as staining for CD44 v3‐containing isoforms.

Conclusion.

CD44 v3‐containing isoforms are associated with HNSCC growth, migration, and matrix metalloproteinase activity and can be identified in lymph node metastasis. © 2007 Wiley Periodicals, Inc. Head Neck, 2007
Myopericytoma of the oral cavity
Authors: Datta Vivekanand , Rawal Yeshwant B. , Mincer Harry H. , Anderson Mark K.
Published: January 2007

Background.

Myopericytoma is a rare mesenchymal neoplasm of pericytic cells demonstrating myoid differentiation. The lesion typically arises within the subcutaneous tissue of the extremities. We report a case that, to the best of our knowledge, is the first case of myopericytoma involving the soft tissue of the oral cavity.

Methods.

A 36‐year‐old woman had a 5‐mm sessile, whitish‐pink, firm tongue nodule. The patient underwent excisional biopsy, and histopathologic examination as well as immunohistochemical analysis were performed.

Results.

The differential diagnosis by histologic analysis included solitary fibrous tumor, myofibroma, glomus tumor, and myopericytoma. The results of immunohistochemical analysis, when combined with the histologic features, led to a diagnosis of myopericytoma.

Conclusions.

Applying strict morphologic criteria and appropriately selective immunohistochemical markers will help to distinguish myopericytoma in the oral cavity. © 2007 Wiley Periodicals, Inc. Head Neck, 2007
Clinical significance of MMP‐2 and MMP‐9 in patients with oral cancer
Authors: Patel Beena P. , Shah Shakuntala V. , Shukla Shilin N. , Shah Pankaj M. , Patel Prabhudas S.
Published: January 2007

Background.

Factors that represent the potential for invasion and metastasis, such as matrix metalloproteinases (MMPs), could predict prognosis of cancer. Therefore, the authors studied plasma and tissue levels of MMP‐2 and MMP‐9 in oral cancer, the leading malignancy in India.

Methods.

Enzyme‐linked immunosorbent assay and gelatin zymography were used for the MMP analysis from plasma and tissue samples, respectively.

Results.

Latent, active, and total forms and activation ratio of MMP‐2 and MMP‐9 were significantly elevated in malignant tissues as compared with adjacent normal tissues. Activation of MMP‐2 was higher than MMP‐9 in malignant tissues. Activation ratio was significantly higher in malignant tissues of the patients with lymph node metastasis as compared with those without lymph node metastasis (p = .005). Plasma MMP‐9 levels were significantly lower in responders as compared with pretreatment levels (p = .002).

Conclusion.

The data indicate that MMP‐2 and MMP‐9 can be useful to identify metastatic phenotype as well as for treatment monitoring in oral cancer. © 2007 Wiley Periodicals, Inc. Head Neck, 2007