bluuebunny/crossref_metadata_2025 huggingface dataset:
Whey protein concentrate hydrogels as bioactive carriers
Authors: Gunasekaran S. , Xiao L. , Ould Eleya M. M.
Published: December 2005

Two sets of heat‐induced hydrogels were prepared from whey protein concentrate (WPC), one set at a constant concentration [15% (w/v)] and varying pHs (pH 5.1–10.0) and the other set at a constant pH (10.0) and varying concentrations (12%, 15%, and 18%). At a given pH, the higher the protein concentration, the shorter was the gelation time and the larger were the equilibrium storage modulus (G) and failure stress. For a given protein concentration, the gelation kinetics and mechanical properties of WPC hydrogels were strongly pH dependent. The swelling behavior of WPC gels was studied at 37.5°C ± 0.5°C. The equilibrium swelling ratio (SR) was at the minimum when pH of the swelling medium was close to the isoelectric point (pI) of the whey protein, and when the swelling medium pH was far from the pI (from 6.0 to 10.0), the SR increased. In particular, when the pH was higher than the pI, the swelling was highly pH sensitive. The higher the WPC concentration used in preparing the hydrogel, the lower was the SR. The controlled drug release properties of the WPC hydrogels were studied using caffeine as the model drug. Consistent with the swelling behavior of the gels, release was slower when the pH of the medium was lower (pH 1.8) than when it was higher (pH 7.5). The SR and the drug release rate decreased significantly when the gels were surface‐coated with alginate. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006
Novel thermosetting resins for SMC applications from linseed oil: Synthesis, characterization, and properties
Authors: Lu Jue , Wool Richard P.
Published: December 2005

New thermosetting resins for applications of sheet‐molding compounds (SMCs) were successfully synthesized from linseed oil, which is the most molecularly unsaturated of all plant oils. The carbon–carbon double bonds were opened by epoxidation, followed by acrylation, and then maleinization, which provided more crosslink sites and added acid functionality on the triglyceride molecules to develop thickening. Dynamic mechanical analysis showed that the storage modulus of these new polymers was approximately 2.5 GPa at 30°C, and the glass‐transition temperature was above 100°C. During maturation the resins reached a molding viscosity quickly and stayed stable. Mechanical tests showed a flexural strength of 100 MPa and a flexural modulus of 2.8 GPa. Thermogravimetric analysis showed a single degradation ranging from 300°C–480°C, which was a result of the carbonization of the crosslinked network. These bio‐based resins are promising as replacements of some petroleum‐based resins in the SMC industry. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006
Review of thermally point‐bonded nonwovens: Materials, processes, and properties
Authors: Michielsen Stephen , Pourdeyhimi Behnam , Desai Prashant
Published: December 2005

Recent research on all aspects of thermally point‐bonded nonwovens has led to considerable improvements in the understanding of material requirements for these nonwovens, the changes that occur during bonding, and the mechanical properties of the resultant nonwoven materials. This article will review (1) how the thermal bonding process transforms the material properties of feed fibers, (2) the implications for material selection, and (3) the resultant failure properties of the bonded nonwoven. The formation of a bond during thermal bonding follows in sequence through three critical steps: (1) heating the web to partially melt the crystalline region, (2) reptation of the newly released chain segments across the fiber–fiber interface, and (3) subsequent cooling of the web to re‐solidify it and to trap the chain segments that diffused across the fiber–fiber interface. The time scales for these processes closely match commercial practice. In addition, adequate pressure is required to compress the fibers that form the bond spots and enhance heat transfer to these fibers. However, pressures typically used in commercial practice are insufficient to increase the melting temperature significantly or to produce significant heating due to compression of the fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006
Modified silicone–PVDF composite hollow‐fiber membrane preparation and its application in VOC separation
Authors: Zhen Hanfei , Jang Steven M. J. , Teo W. K. , Li K.
Published: December 2005

Polydimethylsiloxanevi–poly(vinylidene fluoride) (PDMSvi–PVDF) composite membranes were prepared using asymmetric PVDF hollow‐fiber membranes as the substrate where a very thin layer of silicone‐based coating material was deposited via a developed dip coating method. The preparation of the composite membranes under various conditions were investigated. In the optimal coating procedure, homogenous and stable oligo‐PDMSvi coating layers as thin as 1–2 μm were successfully deposited on the surface of PVDF membranes. The developed PDMSvi–PVDF composite membranes were applied for separation of a wide variety of volatile organic compounds (benzene, chloroform, acetone, ethyl acetate, and toluene). The results showed that the PDMSvi–PVDF hollow‐fiber composite membranes that had been developed exhibited very high removal efficiency (>96%) for all the VOCs examined under favorable operating conditions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006
Miscibility studies on linseed oil epoxy blend with poly(methacrylic acid)
Authors: Ashraf S. M. , Ahmad Sharif , Riaz Ufana , Alam Manawwer , Sharma H. O.
Published: December 2005

With the aim to utilize a vegetable oil epoxy, a product from a sustainable resource, for improving the properties of polymethacrylic acid (PMAA), the blends of the latter with the epoxy of linseed oil were prepared in solution by mechanical mixing of the requisite amounts of the two components in dimethylsulphoxide. Freestanding films of the blend were cast. The miscibility of the two components was investigated by viscosity, ultrasonic, and density measurements which showed that the two components were semicompatible in solution. The compatibility in solid phase was also examined by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), which revealed that linseed oil epoxy (LOE) and PMAA were incompatible. The films of blend of all compositions were found to be sticky, which was caused by the oozing of LOE. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006
Bayesian conformational analysis of ring molecules through reversible jump MCMC
Authors: Nolsøe Kim , Kessler Mathieu , Pérez José , Madsen Henrik
Published: December 2005

In this paper, we address the problem of classifying the conformations of m‐membered rings using experimental observations obtained by crystal structure analysis. We formulate a model for the data generation mechanism that consists in a multidimensional mixture model. We perform inference for the proportions and the components in a Bayesian framework, implementing a Markov chain Monte Carlo (MCMC) reversible jump algorithm to obtain samples of the posterior distributions. The method is illustrated on a simulated data set and on real data corresponding to cyclo‐octane structures. Copyright © 2005 John Wiley & Sons, Ltd.
Interaction of Bovine Serum Albumin with Chrysotile: Spectroscopic and Morphological Studies
Authors: Falini Giuseppe , Foresti Elisabetta , Lesci Isidoro G. , Lunelli Bruno , Sabatino Piera , Roveri Norberto
Published: December 2005

The biodurability of chrysotile fibers, which is related to their cytotoxicity and mutagenic responses, is strongly affected by the surface chemical adsorption of biological molecules. Natural chrysotile is a heterogeneous material in both structure and composition. The availability of synthetic stoichiometric chrysotile of constant structure and uniform morphology has allowed us to investigate its interaction with bovine serum albumin (BSA). By using transmission electron microscopy (TEM) and atomic force microscopy (AFM), we have obtained the first morphological evidence of albumin adsorption onto chrysotile nanocrystals. FTIR spectroscopy was used to quantify modifications of BSA secondary structure that were induced by the surface interaction. The protein transition to β‐turns allows a stronger interaction between the protein hydrophilic side‐chains and the charged asbestos surface, which is consistent with hydrogen bonds involving the superficial OH groups. Synthetic stoichiometric chrysotile nanocrystals were shown to be an ideal reference standard with which to study the interaction of asbestos fibers with biological systems, in order to elucidate the chemical mechanisms of asbestos toxicity.
A Synthetic Camel Anti‐Lysozyme Peptide Antibody (Peptibody) with Flexible Loop Structure Identified by High‐Resolution Affinity Mass Spectrometry
Authors: Marquardt Andreas , Muyldermans Serge , Przybylski Michael
Published: December 2005

We describe the synthesis and characterisation of the fully functional molecular recognition structure of a 26‐amino acid residue peptide antibody, referred to as peptibody, designed from a monoclonal single‐domain antibody fragment derived from a camel heavy‐chain antibody. The CDR3 region (CDR=complementarity determining region) of the cAbLys3 camel antibody fragment, which binds to the active site of hen eggwhite lysozyme (HEL) and acts as a potent enzyme inhibitor by mimicking an oligosaccharide substrate, was prepared by solid‐phase peptide synthesis. To obtain a closed loop‐like structure resembling that in the crystal structure, N‐ and C‐terminal cysteine residues were added to the linear peptide and oxidised to a cyclic disulfide‐bridged peptide by using dimethylsulfoxide. A further, internal cysteine‐12 residue was acetamidomethyl‐protected to prevent possible oxidative byproducts. Affinity separation on a lysozyme microcolumn combined with MALDI‐TOF mass spectrometry revealed that the peptide resumed high affinity to lysozyme only after deprotection of Cys‐12, suggesting the importance of this paratope sequence for epitope recognition. The complex of lysozyme and active peptibody was characterised directly by conducting high‐resolution ESI‐FTICR mass spectrometry, which provided a molecular comparison of affinities for linear and cyclic peptibodies.
Computational Study of Solvent Effects and the Vibrational Spectra of Anderson Polyoxometalates
Authors: Bridgeman Adam J.
Published: December 2005

The structures and vibrational frequencies of the type II Anderson heteropolyanions [TeMo6O24]6− and [IMo6O24]5−have been calculated by using density functional theory using a number of common functionals and basis sets. For the first time, Raman intensities have been calculated and the effect of solvent on the modeling has been investigated. The calculated IR and Raman spectral traces are in good agreement with experiment allowing the characteristic group frequencies for this class of polyoxometalate to be identified. The stretching vibrations of the molybdenum–oxygen bonds are predicted to occur at somewhat lower frequencies than in the type I polyoxometalates. Stretching of the heteroatom–oxygen bonds occurs at significantly lower frequencies than in the Keggin anions as a simple consequence of the higher coordination number of the central heteroatom in the Anderson systems. For the [Mo2O7]2− and [Mo6O19]2− ions, the relatively low negative charge leads to small structural changes when solvent is included. In these systems, solvent leads to an increase in the bond polarity and a decrease in the covalent bond orders, resulting in decreases in the calculated frequencies. For the Anderson anions, the higher negative charges leads to greater solvent effects with contraction of the clusters and increases in the frequencies of bands due to stretching of the two, cis‐related molybdenum–oxygen bonds.
Enhanced Solubilization of Bovine Serum Albumin in Reverse Micelles by Compressed CO2
Authors: Feng Xiaoying , Zhang Jianling , Chen Jing , Han Buxing , Shen Dong
Published: December 2005

The effect of compressed CO2 on the solubilization of bovine serum albumin (BSA) in water/sodium bis‐(2‐ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelles was studied by observing phase behavior and recording UV‐visible spectra under different conditions. The pH values within the water cores of reverse micelles at different CO2 pressures were also determined. The solubilization capacity of the reverse micelles for the protein increased considerably as CO2 pressure increased within the low‐pressure range, but decreased at higher CO2 pressures, so that the micelles eventually lost their ability to solubilize the protein. The effect of CO2 on the stability of the reverse micelles played an important role in the relationship between pressure and protein solubility. A “multicomplex” model was proposed to explain these effects. The different solublization capacities within different pressure ranges demonstrates the unique advantage of using compressed CO2 in the extraction of proteins with reverse micelles.
Electrochemistry and Photophysics of Donor‐Substituted Triarylboranes: Symmetry Breaking in Ground and Excited State
Authors: Stahl Rainer , Lambert Christoph , Kaiser Conrad , Wortmann Rüdiger , Jakober Ruth
Published: December 2005

We synthesized a series of amino substituted triarylboranes (TABs) 1–3 by copper(I)‐catalyzed cross‐coupling reactions. The title compounds were investigated by means of cyclic voltammetry (CV) and UV‐visible absorption and fluorescence spectroscopy. Electrochemical oxidation of tris(4‐carbazolyl‐2,6‐dimethylphenyl)borane (3) leads to the formation of an electroactive polymer film on the electrode surface. The charge‐transfer (CT) absorption band of all three TABs shows a pronounced negative solvatochromism, while the emission is positively solvatochromic. By combining Jortner's theory, AM1 computations, and electrooptical absorption measurements (EOAM), this unexpected behavior was shown to be due to a dipole inversion upon S0→S1 excitation. Furthermore, polarized steady‐state fluorescence spectroscopy and EOAM prove that the ground‐state geometry of 3 is of lower symmetry than D3 and that the excitation energy can be transferred from one subchromophore to another within the lifetime of the excited state. Exciton‐coupling theory was used to quantitatively analyze this excitation transfer.
One‐Electron Redox Processes during Polyoxometalate‐Mediated Photocatalytic Reactions of TiO2 Studied by Two‐Color Two‐Laser Flash Photolysis
Authors: Tachikawa Takashi , Tojo Sachiko , Fujitsuka Mamoru , Majima Tetsuro
Published: December 2005

The one‐electron redox processes of several compounds during polyoxometalate (POM)‐mediated photocatalytic reactions of TiO2 were investigated using the two‐color two‐laser flash‐photolysis technique. The efficiency of the one‐electron oxidation of aromatic sulfides by the trapped hole (htr+) or the surface‐bound OH radical (OHs.) is found to be significantly enhanced due to electron transfer from the conduction band (CB) of TiO2 to the POM. The efficiency of the electron transfer from the CB of TiO2 to the POM decreases in the order H2W12O406− < SiW12O404− < PW12O403−, that is, it depends on the reduction potential (Ered) of the POMs. Electron injection from PW12O404− in the excited state (PW12O404−*) to the CB of TiO2 was clearly observed using the two‐color two‐laser flash‐photolysis technique. Storage of electrons in the TiO2/PW12O403−/methyl viologen (MV2+) ternary system was also achieved upon two‐color two‐laser irradiation.
Gold(I)‐Catalyzed Cyclizations of 1,6‐Enynes: Alkoxycyclizations and exo/endo Skeletal Rearrangements
Authors: Nieto‐Oberhuber Cristina , Muñoz M. Paz , López Salomé , Jiménez‐Núñez Eloísa , Nevado Cristina , Herrero‐Gómez Elena , Raducan Mihai , Echavarren Antonio M.
Published: December 2005

Gold(I) complexes are the most active catalysts for alkoxy‐ or hydroxycyclization and for skeletal rearrangement reactions of 1,6‐enynes. Intramolecular alkoxycyclizations also proceed efficiently in the presence of gold(I) catalysts. The first examples of the skeletal rearrangement of enynes by the endocyclic cyclization pathway are also documented. Iron(III) is also able to catalyze exo and endo skeletal rearrangements of 1,6‐enynes, although the scope of this transformation is more limited. The gold(I)‐catalyzed endocyclic cyclization proceeds by a mechanism different from those followed in the presence of PdII, HgII, or RhI catalysts.
Gold(I)‐Catalyzed Intramolecular Cyclopropanation of Dienynes
Authors: Nieto‐Oberhuber Cristina , López Salomé , Muñoz M. Paz , Jiménez‐Núñez Eloísa , Buñuel Elena , Cárdenas Diego J. , Echavarren Antonio M.
Published: December 2005

Gold(I) complexes are the most active catalysts for the biscyclopropanation of dienynes to form tetracyclic compounds. PtII and ZnII are also able to promote the biscyclopropanation, although less efficiently. The configurations obtained in all cases with the use of gold(I) catalysts can be explained by the pathway proceeding through anti cyclopropyl gold carbenes. Similar intermediates are most probably involved in reactions catalyzed by RuII and PtII. Two different cyclopropanation pathways have been found; they depend on the structures of the cyclopropyl gold carbenes (anti or syn) and the relative arrangements of the metal carbenes and the alkenes.
Comparison of β‐tubulin mRNA and protein levels in 12 human cancer cell lines
Authors: Hiser Laree , Aggarwal Ashish , Young Rebekah , Frankfurter Anthony , Spano Anthony , Correia John J. , Lobert Sharon
Published: December 2005

Antimitotic drugs are chemotherapeutic agents that bind tubulin and microtubules. Resistance to these drugs is a major clinical problem. One hypothesis is that the cellular composition of tubulin isotypes may predict the sensitivity of a tumor to antimitotics. Reliable and sensitive methods for measuring tubulin isotype levels in cells and tissues are needed to address this hypothesis. Quantitative measurements of tubulin isotypes have frequently relied upon inferring protein amounts from mRNA levels. To determine whether this approach is justified, protein and mRNA levels of β‐tubulin isotypes from 12 human cancer cell lines were measured. This work focused on only β‐tubulin isotypes because we had readily available monoclonal antibodies for quantitative immunoblots. The percentage of β‐tubulin isotype classes I, II, III, and IVa + IVb mRNA and protein were compared. For β‐tubulin class I that comprises >50% of the β‐tubulin protein in 10 of the 12 cell lines, there was good agreement between mRNA and protein percentages. Agreement between mRNA and protein was also found for β‐tubulin class III. For β‐tubulin classes IVa + IVb, we observed higher protein levels compared to mRNA levels. β‐Tubulin class II protein was found in only four cell lines and in very low abundance. We conclude that quantitative Western blotting is a reliable method for measuring tubulin isotype levels in human cancer cell lines. Inferring protein amounts from mRNA levels should be done with caution, since the correspondence is not one‐to‐one for all tubulin isotypes. Cell Motil. Cytoskeleton 2006. © 2005 Wiley‐Liss, Inc.
Subsequent therapy can be administered after tositumomab and iodine I‐131 tositumomab for non‐Hodgkin lymphoma
Authors: Dosik Alan D. , Coleman Morton , Kostakoglu Lale , Furman Richard R. , Fiore Jennifer M. , Muss Daniel , Niesvizky Ruben , Shore Tsiporah , Schuster Michael W. , Stewart Patricia , Vallabhajosula Shankar , Goldsmith Stanley J. , Leonard John P.
Published: December 2005

BACKGROUND

Iodine I‐131 tositumomab is a well tolerated and effective therapy for recurrent low‐grade and transformed low‐grade non‐Hodgkin lymphoma (NHL). Hematologic reserve after radioimmunotherapy (RIT) is an important consideration when subsequent therapy is required.

METHODS

One hundred fifty‐five patients who received treatment with I‐131 tositumomab were assessed, and 68 patients had progressive disease after RIT. The median age (n = 68 patients) was 59 years (range,18–82 yrs), and patients received a median of 2 pre‐RIT regimens (range,1–8 regimens), including 66% who received anthracycline, 19% who received platinum, and 50% who received fludarabine.

RESULTS

The median time to disease progression (among progressors) was 168 days (range, 19–771 days). At the time they developed recurrent disease, patients had median white blood cell count (WBC) of 4.9 K cells/μL (range, 1.1–21.4 K cells/μL), a median absolute neutrophil count (ANC) of 3.25 K cells/μL (range, 0.59–8.20 K cells/μL), a median platelet count of 130 K cells/μL (range, 9–440 K cells/μL), and there was no significant difference between pre‐RIT and recurrence values except for the platelet count (P < 0.05). No patient demonstrated a WBC < 1.0 K cells/μL or an ANC < 0.5 K cells/μL, although 1 patient had a platelet count < 10 K cells/μL. Twenty‐four patients subsequently received no further chemotherapy; and, in 21 patients (88%), hematologic parameters appeared to allow subsequent chemotherapy if necessary (blood counts: National Cancer Institute Grade 0–2). Among 44 patients (65%) who received further chemotherapy (median, 2 regimens; range, 1–4 regimens), 19 patients (43%) were treated with anthracyclines, 17 patients (39%) were treated with platinum, 10 patients (23%) were treated with fludarabine, and 13 patients (30%) underwent stem cell transplantation. Disease improvement occurred in most patients, although 18 patients died (40%) after further chemotherapy, predominantly from refractory lymphoma.

CONCLUSIONS

Most patients with progressive disease after treatment with iodine I‐131 tositumomab were able to receive subsequent therapy, including cytotoxic chemotherapy and stem cell transplantation. Cancer 2006. © 2005 American Cancer Society.
Cytokeratin 20 expression identifies a subtype of pancreatic adenocarcinoma with decreased overall survival
Authors: Matros Evan , Bailey Gerald , Clancy Thomas , Zinner Michael , Ashley Stanley , Whang Edward , Redston Mark
Published: December 2005

BACKGROUND

Cytokeratins are markers of epithelial cell differentiation useful in determining histogenesis for malignancies with an unknown primary. Application of this principle to a single malignancy may identify cancer subtypes with altered developmental programs. Herein, we investigate the relevance of two widely used cytokeratins (CKs), 7 and 20, to subtype pancreas cancer and identify associations with clinical features.

METHODS

A tissue microarray was constructed using tumor specimens from 103 patients who underwent resection for pancreatic adenocarcinoma with curative intent. A subset of resection specimens was evaluated for pancreatic intraepithelial neoplasia (PanIN) lesions. Tissues were immunostained by using specific anticytokeratin 7 and 20 monoclonal antibodies.

RESULTS

CK 7 and 20 expression was present in 96% and 63% cases of pancreatic adenocarcinoma, respectively. Ubiquitous CK 7 expression precluded further analysis. Tumoral CK 20 expression was not associated with any histopathologic parameter but correlated with worse prognosis when considered as either a dichotomous (P = 0.0098) or continuous (P = 0.007) variable. In a multivariate model, tumoral CK 20 expression remained a significant independent prognosticator. CK 20 expression was absent in all PanIN lesions from eight resection specimens in which the tumor component was negative for CK 20. In contrast, presence of tumoral CK 20 was highly concordant with its expression in corresponding PanINs.

CONCLUSIONS

CK 20 expression defines a subtype of pancreas cancer with important biologic properties. When present, CK 20 expression is an early event in pancreatic carcinogenesis identifiable in precursor lesions. Further studies to identify the underlying genetic changes associated with this altered developmental pathway are warranted. Cancer 2006. © 2005 American Cancer Society.
CpG island hypermethylation in progression of esophageal and gastric cancer
Authors: Sato Fumiaki , Meltzer Stephen J.
Published: December 2005

The upper gastrointestinal (GI) cancers have various carcinogenic pathways and precursor lesions, such as dysplasia for esophageal squamous cell carcinoma, Barrett esophagus for esophageal adenocarcinoma, and intestinal metaplasia for the intestinal‐type of gastric cancer. Recently, many epigenetic events in carcinogenic pathways have been revealed, along with genomic and genetic alterations. This information has provided deeper insight into an understanding of the mechanisms of upper GI carcinogenesis. Moreover, detection methods of aberrant methylation have been applied to clinical fields to stratify high‐risk groups, detect early cancer, and to predict clinical outcomes. In this review, a variety of information is summarized regarding gene hypermethylation in esophageal and gastric cancer. Cancer 2006. © 2005 American Cancer Society.
Hyperbolic limit of the Jin‐Xin relaxation model
Authors: Bianchini Stefano
Published: December 2005

We consider the special Jin‐Xin relaxation modelWe assume that the initial data ($u_0, \epsilon u_{0,t}$) are sufficiently smooth and close to ($\bar{u},0$) inL∞and have small total variation. Then we prove that there exists a solution ($u^\epsilon (t), \epsilon u^{\epsilon}_t (t)$) with uniformly small total variation for allt≥ 0, and this solution depends Lipschitz‐continuously in theL1norm with respect to time and the initial data.

Letting$\epsilon \longrightarrow 0$, the solution$u^\epsilon$converges to a unique limit, providing a relaxation limit solution to the quasi‐linear, nonconservative systemThese limit solutions generate a Lipschitz semigroup$\cal{S}$on a domain$\cal{D}$containing the functions with small total variation and close to$\bar{u}$. This is precisely the Riemann semigroup determined by the unique Riemann solver compatible with (0.1). © 2005 Wiley Periodicals, Inc.
Information processing, memories, and synchronization in chaotic neural network with the time delay
Authors: Bondarenko Vladimir E.
Published: December 2005

Information processing and two types of memory in an analog neural network model with time delay that produces chaos similar to the human and animal EEGs are considered. There are two levels of information processing in this neural network: the level of individual neurons and the level of the neural network. Similar to the state of brain, the state of chaotic neural network is defined. It is characterized by two types of memories (memory I and memory II) and correlation structure between the neurons. In normal (unperturbed) state, the neural network generates chaotic patterns of averaged neuronal activities (memory I) and patterns of oscillation amplitudes (memory II). In the presence of external stimulation, the activity patterns change, showing changes in both types of memory. As in experiments on stimulation of the brain, the neural network model shows synchronization of neuronal activities due to stimulus measured by Pearson's correlation coefficient. An increase in neural network asymmetry (increase of the neural network excitability) leads to the phenomenon similar to the epilepsy. Modeling of brain injury, Parkinson's disease, and dementia is performed by removing and weakening interneuron connections. In all cases, the chaotic neural network shows a decrease of the degree of chaos and changes in both types of memory similar to those observed in experiments with healthy human subjects and patients with Parkinson's disease and dementia. © 2005 Wiley Periodicals, Inc. Complexity 11:39–52, 2005
A model for glioma growth
Authors: Khain Evgeniy , Sander Leonard M. , Stein Andrew M.
Published: December 2005

Glioblastoma Multiforme (GBM) is the most invasive form of primary brain tumor. We propose a mathematical model that describes such tumor growth and allows us to describe two different mechanisms of cell invasion: diffusion (random motion) and chemotaxis (directed motion along the gradient of the chemoattractant concentration). The results are in a quantitative agreement with recent in vitro experiments. It was observed in experiments that the outer invasive zone grows faster than the inner proliferative region. We argue that this feature indicates transient behavior, and that the growth velocities tend to the same constant value for larger times. A longer‐time experiment is needed to verify this hypothesis and to choose between the two basic mechanisms for tumor growth. © 2005 Wiley Periodicals, Inc. Complexity 11: 53–57, 2005
Synthesis and structure of the three‐dimensional coordination polymer [Ag3hmt3(μ3 ‐btc)]·5H2O
Authors: Qin Shoubo , Lu Sheming , Ke Yanxiong , Li Jianmin , Zhou Shuxi , Wu Xintao , Du Wnxin
Published: December 2005

A new coordination polymer, [Ag3hmt3(μ3 ‐btc)]·5H2O (1) (hmt = hexamethylenetetramine, btc=1,3,5‐benzenetricarboxlic), has been successfully synthesized. Crystal data: P21/a, a = 11.9906(2) Å, b = 17.3689(2) Å, c = 16.96100(10) Å, β = 101.9820(14)°, V = 3455.40(7) Å3, Z = 4, Dc = 2.002 Mg/m3. In the hexagonal structure of Ag‐hmt unit, each Ag‐hmt unit comprises three Ag atoms and three hmt ligands. The μ3 ‐btc ligands bridge adjacent two‐dimensional honeycomb‐like Ag‐hmt layers to form three‐dimensional networks. Structure analysis show that hydrogen bonds play a key role for the stable structure in the compounds. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crystal structure of N‐(2‐methoxyphenyl)‐3,6‐diphenyl‐1,4‐dihydro‐1,2,4,5‐tetrazine‐1‐carbonamide
Authors: Rao Guo‐Wu , Hu Wei‐Xiao
Published: December 2005

The title compound, C22H19N5O2, was prepared and its structure was determined by X‐ray diffraction [CCDC 216074]. The compound crystallizes from ethanol in the orthorhombic system, space group P212121, with unit cell parameters: a =10.048(1) Å, b = 13.935 (2) Å, c =14.607(2) Å, Z =4, and V=2045.3(5) Å3. The crystal structure was solved by direct methods and refined by full‐matrix least‐squares to a final R‐value of 0.0516 with 3621 unique reflections. The central six‐membered ring of the compound has a boat conformation and is not homoaromatic, in which adjacent atoms N1 and N4 deviate from the plane of the ring by 0.4546(33) Å and 0.3786(33) Å, respectively. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and structural conformation of N‐substituted 1,4‐dihyropyridine derivatives
Authors: Mahendra M. , Doreswamy B. H. , Sridhar M. A. , Shashidhara Prasad J. , Parecha A. R. , Patel J. A. , Manvar D. , Dholaria K. , Shah A.
Published: December 2005

N‐(Phenyl)‐3,5‐dicarbethoxy‐2,6‐dimethyl‐4‐(phenyl)‐1,4‐dihydropyridine (A) and N‐(4‐methoxy phenyl)‐‐3,5 dicarbethoxy‐2,6 dimethyl‐4‐(3‐nitro phenyl)‐1,4‐dihydropyridine (B) has been synthesized as per scheme and characterized by the X‐ray diffraction method. The compound A crystallizes in monoclinic space group P21/c with cell parameters a = 9.2770(11)Å, b = 8.6410(5)Å, c = 27.601(3)Å, β = 97.724(3)°, Z = 4. The compound B crystallizes in monoclinic space group P21/c with cell parameters a = 11.229(6), b = 12.746(7)Å, c =17.606(6)Å, β = 104.531(3)°, Z = 4. The structures exhibit both intra and intermolecular hydrogen bonds. Dihydropyridine ring of both the compounds adopt a flat boat conformation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and characterization of compounds LixMn1+xFe2–2xO4 with spinel structure in the quasiternary system “LiO0,5 – MnOx – FeOx“
Authors: Wende C. , Langbein H.
Published: December 2005

The thermal decomposition of freeze‐dried Li‐Mn(II)‐Fe(III)‐formate precursors was investigated by means of DTA, TG and mass spectroscopy. By the thermal treatment of the prefired precursors between 400 and 1000°C, single phase solid solutions LixMn1+xFe2–2xO4 (0 ≤ x ≤ 1) with cubic spinel structure were obtained. To get single phase spinels, special conditions concerning the temperature T and the oxygen partial pressure p(O2) during the synthesis are required. Because of the high reactivity of the freeze‐dried precursors, in comparison with the conventional solid state reaction, the reaction temperature can be lowered by 200°C. The cation distribution and the properties of the Li‐Mn‐ferrites were studied by chemical analysis, X‐ray powder diffraction and magnetization measurements. It was found that for high substitution rates, almost all lithium occupies the tetrahedral coordinated A‐sites of the spinel lattice AB2O4, while at small x‐values, lithium ions are distributed over the tetrahedral and octahedral sites. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and X‐ray powder diffraction studies of semiconducting alloys in the system AgCd2‐xZnxGaS4
Authors: Parasyuk O. V. , Olekseyuk I. D. , Dzham O. A. , Pekhnyo V. I.
Published: December 2005

X‐ray powder technique was used in the investigation of AgCd2GaS4–'AgZn2GaS4' section to determine the region of AgCd2GaS4‐based solubility. It was established that the solid solution forms up to 75 mol.% 'AgZn2GaS4'. The refinement of AgCd0.5Zn1.5GaS4 structure was performed. This alloy crystallizes in orthorhombic structure (space group Pmn21 ) with unit cell parameters a =0.78772(2), b =0.67221(2), c =0.64019(2) nm, V =0.33899(3) nm3. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recharging processes of Cr ions in Mg2SiO4 and Y3Al5O12 crystals under influence of annealing and γ ‐ irradiation
Authors: Kaczmarek S. M. , Chen W. , Boulon G.
Published: December 2005

Recharging processes of chromium ions were investigated for Mg2SiO4:Mg, Cr single crystals using annealing in O2 and in air and γ‐irradiation, as compare to YAG :Ca, Cr single crystals. The formation of tetravalent Cr ions in the Mg2SiO4 :Mg, Cr is related not only to the initial Cr content in the melt, oxygen partial pressure and O2‐ vacancy existing in the crystal, but also to the external field such as γ‐irradiation. The additional absorption after γ‐irradiation shows the decrease in intensity of the absorption of Cr3+ and Cr4+ ions in some part of the spectrum and increase in the other giving evidence on recharging effects between Cr3+ and Cr4+. There arises also color centers observed between 380 nm and 570 nm that may participate in energy transfer of any excitation to Cr4+ giving rise to Cr4+ emission. Opposite to forsterite crystal, absorption spectrum of YAG:Ca, Cr crystal after γ‐irradiation reveals only increase in the absorption of the Cr bands. The observed behavior of the absorption spectrum of YAG:Ca, Cr crystal under influence of γ‐irradiation suggests that γ‐irradiation ionizes only Cr ions. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermal decomposition study of ZnHg(SCN)4 in air
Authors: Wang X. Q. , Xu D. , Li S. G. , Huang J. , Du W.
Published: December 2005

Thermal decomposition of ZnHg(SCN)4 (ZMTC) in air was investigated by means of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The intermediates and final products of the thermal decomposition were identified by X‐ray powder diffraction at room temperature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transmission electron microscopy and Rutherford backscattering spectrometry studies of Ag2Te films formed from Ag‐Te thin film couples
Authors: Mohanty B. C. , Kasiviswanathan S.
Published: December 2005

Formation of Ag2Te thin films from room temperature (300 K) solid state reaction of Ag and Te thin film couples is investigated. Rutherford Backscattering Spectrometry (RBS) studies confirmed the complete miscibility of the couples and the stoichiometry of the resulting Ag2Te. Structural analysis by Transmission Electron Microscopy (TEM) showed a fine‐grained structure with monoclinic and orthorhombic phases. Annealing at high temperatures resulted in the growth of giant crystallites with monoclinic phase at random sites. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoacoustic study of the thermal properties of calcium carbonate – the major constituent of pancreatic calculi
Authors: Ramachandran E. , Raji P. , Ramachandran K. , Natarajan S.
Published: December 2005

The study of the thermal properties of condensed matter is very essential both for crystallizing and thermal energy induced fracturing of solid materials. Photoacoustic spectroscopy (PAS) is a recently developed, nondestructive testing (NDT) tool, used for analyzing the surface properties of materials. This method is used here to determine the thermal diffusivity and thermal conductivity of the gel grown single crystals of calcium carbonate (CC), which is the major constituent of pancreatic calculi. Characterization of CC was made using single crystal X‐ray diffraction and density determination. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
DC conduction processes in nickel‐dimethylglyoxime films
Authors: Dakhel A. A.
Published: December 2005

Thin nickel‐dimethylglyoxime Ni(DMG)2 films of amorphous and crystalline structures were prepared by vacuum sublimation on glass and p‐type Si substrates. The films were characterised by X‐ray diffraction. The constructed Al/Ni(DMG)2/Si(p) MIS devices were characterised by the measurement of their capacitance as a function of gate voltage. The dc‐electrical conduction of the Ni(DMG)2 films grown on silicon substrate were studied at room temperature and in a temperature range of 293 ‐ 323 K. The dc current‐voltage data of both amorphous and crystalline insulator follow the trap‐charge‐limited space‐charge‐limited conductivity mechanism with the characteristic trap energy Et of about 0.05 eV. The total concentration and the energy distribution of the traps were determined. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adiabatic bond charge model for lattice dynamics of ternary chalcopyrite semiconductors
Authors: Gürel T. , Eryiğit R.
Published: December 2005

The adiabatic bond charge model of Rustagi and Weber is extended to study lattice dynamical properties of ternary chalcopyrite semiconductors AgGaS2, AgGaSe2, CuInS2, CuInSe2, CuGaS2, CuGaSe2, CuAlS2 and CuAlSe2. The new model calculations agree well with the results of Raman/IR and neutron measurements of Brillouin zone center phonon frequencies for both low and high frequency modes which was difficult for other phenomenological lattice dynamical models. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rapid crystal growth without inherent supersaturation induced by nanoscale fluid flows?
Authors: Jones M. J. , Dette S. S. , Ulrich J.
Published: December 2005

Crystal growth is a process that only takes place under non‐equilibrium conditions and a necessary prerequisite is that the crystal is exposed to a phase that is supersaturated in the material the crystal is composed of, be it a solution, a vapour or a supercooled melt. In industrial mass crystallization the growth rate for a population of crystals (in suspension growth processes [1]) rarely exceeds mean linear velocities of 10‐7 ms‐1. Here we present a mass crystallization process which is accompanied by rapid crystal growth several orders of magnitude faster and into a region of solution that is without inherent supersaturation. The material investigated is a solid hydrate that exhibits a solution mediated phase transition to its anhydrous form in the presence of methanol [2]. The phase transition is initiated simply by placing an amount of hydrate crystals into the solvent and is characterized by the rapid emergence of needle‐shaped crystals. The needles emanate from the crystal faces of the hydrate crystals and grow into the solution, which is nominally free of the substance to be crystallized. The high growth rate of the crystals, which of the order of up to 10‐4 ms‐1 is surprising. Although rapid needle growth has been observed before [3‐9], to date a satisfactory explanation for needles growing under the abovementioned conditions is still outstanding. Based upon the topology of the crystals we propose a tentative mechanism for this phenomenon capable of explaining the unusually rapid growth and highlight those questions that need addressing in order to verify this mechanism. X‐ray powder diffraction is used to characterize the crystal phase of the needles; confocal fluorescence microscopy reveals that the needles are hollow. The width of these needles is between 0.5 and 5 μm, their length appears to be limited only by the amount of hydrate available for their formation. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Severe combined immunodeficiency and microcephaly in siblings with hypomorphic mutations in DNA ligase IV
Authors: Buck Dietke , Moshous Despina , de Chasseval Régina , Ma Yunmei , le Deist Françoise , Cavazzana‐Calvo Marina , Fischer Alain , Casanova Jean‐Laurent , Lieber Michael R. , de Villartay Jean‐Pierre
Published: December 2005

DNA double‐strand breaks (dsb) during V(D)J recombination of T and B lymphocyte receptor genes are resolved by the non‐homologous DNA end joining pathway (NHEJ) including at least six factors: Ku70, Ku80, DNA‐PKcs, Artemis, Xrcc4, and DNA ligase IV (Lig4). Artemis and Lig4 are the only known V(D)J/NHEJ factors found deficient in human genetic disorders. Null mutations of the Artemis gene result in a complete absence of T and B lymphocytes and increased cellular sensitivity to ionizing radiations, causing radiosensitive‐SCID. Mutations of Lig4 are exclusively hypomorphic and have only been described in six patients, four exhibiting mild immunodeficiency associated with microcephaly and developmental delay, while two patient had leukemia. Here we report a SCID associated with microcephaly caused by compound heterozygous hypomorphic mutations in Lig4. Residual activity of Lig4 in these patients is underscored by a normal pattern of TCR‐α and ‐β junctions in the T cells of the patients and a moderate impairment of V(D)J recombination as tested in vitro. These observations contrast with the severity of the clinical immunodeficiency, suggesting that Lig4 may have additional critical roles in lymphocyte survival beyond V(D)J recombination.
Self‐Assembly of a Tetranuclear CoIII‐Metallacycle from the Reaction of a Bis(benzene‐o‐dithiolato) Ligand with CoIIand Subsequent Aerial Oxidation
Authors: Hahn F. Ekkehardt , Kreickmann Thorsten , Pape Tania
Published: December 2005

The bis(benzene‐o‐dithiol) ligand [(HS)2‐2,3‐C6H3–CH2–C6H3‐2,3‐(SH)2] (H4‐1) reacts, after deprotonation with Li2CO3, with CoCl2·6H2O. Aerial oxidation in methanol gives the tetranuclear metallacycle Li4[Co4(1)4]. The X‐ray structure analysis of (PNP)4[Co4(1)4] (7) reveals a cyclic structure in which each of the bis(benzene‐o‐dithiolato) ligands forms a bridge between two cobalt centers. Two differently coordinated cobalt atoms (synandanti) are observed in the tetranuclear complex. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Mutations in mitochondrial‐encoded cytochrome c oxidase subunits I, II, and III genes detected in Alzheimer's disease using single‐strand conformation polymorphism
Authors: Hamblet Natasha S. , Ragland Brian , Ali Mervat , Conyers Barbara , Castora Frank J.
Published: December 2005

A “mitochondrial hypothesis” of late onset Alzheimer's disease (AD) has been proposed. Biochemical studies indicate that there is a significant decrease in cytochrome oxidase (CO) activity as well as perturbed CO I and CO III mRNA levels in platelets and brain tissue from Alzheimer's patients. Using the electrophoretic mutation detection technique SSCP and DNA sequencing, we have identified 20 point mutations in the mitochondrial‐encoded CO subunits (CO I, II, and III) in AD and age‐matched control brain samples. Eight of the mutations are new variants of the mitochondrial genome. The efficiency of SSCP in detecting mutations in the CO subunits was estimated to be 80% when compared to dideoxy sequencing. One of the mutations (at position 9861) results in a phenylalanine→leucine substitution at a highly conserved residue in CO III. CO activity was reduced by an average of 35% in all AD brains compared to age‐matched control samples, which agrees with previous reports. CO activity in one of the AD brain samples carrying the 9861 mutation decreased by 80% relative to control brain samples, suggesting that the phenotypic expression of this mutation may result in reduced CO activity and compromised mitochondrial function.
Sustained‐release delivery systems of triclosan for treatment of Streptococcus mutans biofilm
Authors: Steinberg Doron , Tal Tamir , Friedman Michael
Published: December 2005

Dental diseases are chronic infections caused by oral bacteria harboring the dental biofilm. Local sustained‐release delivery systems prolong the duration of a drug in the oral cavity, thus enhancing its therapeutic potential, while reducing its side effects. Triclosan is an agent that was found to have an antibacterial effect against oral bacteria. However, its substantivity in the oral cavity is low, resulting in reduced antibacterial efficiency. The purpose of this study was to develop a local sustained release device containing triclosan and to test its antibacterial efficacy on Streptococcus mutans biofilm. Our results show that we can formulate an ethylcellulose‐based, nondegradable, sustained‐release device in which 80% of the loaded triclosan is released over a 10‐day period. The release rate of triclosan corresponded to the Higuchi's planar homogenous diffusion release model (r2 = 0.998). A degradable local sustained‐release delivery based on a methacrylate ester matrix was also developed for a faster release rate of triclosan. The release kinetics in those types of sustained‐release delivery systems was erosion control. The local sustained‐release delivery system significantly affected the viability of S. mutans in biofilm compared to placebo as was tested by confocal laser scanning microscopy. Our in vitro results show that triclosan can be incorporated into degradable or nondegradable sustained‐release drug delivery systems. The release of triclosan from the local sustained‐release delivery system can be controlled, thus extending its antibacterial properties. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
First steps towards tissue engineering of small‐diameter blood vessels: Preparation of flat scaffolds of collagen and elastin by means of freeze drying
Authors: Buttafoco L. , Engbers‐Buijtenhuijs P. , Poot A. A. , Dijkstra P. J. , Daamen W. F. , van Kuppevelt T. H. , Vermes I. , Feijen J.
Published: December 2005

Porous scaffolds composed of collagen or collagen and elastin were prepared by freeze drying at temperatures between –18 and –196°C. All scaffolds had a porosity of 90–98% and a homogeneous distribution of pores. Freeze drying at –18°C afforded collagen and collagen/elastin matrices with average pore sizes of 340 and 130 μm, respectively. After 20 successive cycles up to 10% of strain, collagen/elastin dense films had a total degree of strain recovery of 70% ± 5%, which was higher than that of collagen films (42% ± 6%). Crosslinking of collagen/elastin matrices either in water or ethanol/water (40% v/v) was carried out using a carbodiimide (N‐(3‐dimethylaminopropyl)‐N′‐ethylcarbodiimide hydrochloride, EDC) in combination with a succinimide (N‐hydroxysuccinimide, NHS) in the presence or absence of a diamine (J230) or by reaction with butanediol diglycidylether (BDGE), followed by EDC/NHS. Crosslinking with EDC/NHS or EDC/NHS/J230 resulted in matrices with increased stiffness as compared to noncrosslinked matrices, whereas sequential crosslinking with the diglycidylether and EDC/NHS yielded very brittle scaffolds. Ethanol/water was the preferred solvent in the crosslinking process because of its ability to preserve the open porous structure during crosslinking. Smooth muscle cells were seeded on the (crosslinked) scaffolds and could be expanded during 14 days of culturing. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006