bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fractal and Non‐Fractal Structure–Property Relationships of Polymer‐Stabilized Liquid Crystals
Authors: Dierking I. 
Published: September 2004

AbstractThe electro‐optic performance of polymer‐stabilized liquid crystals (PSLCs) depends in a complex manner on the morphology of the stabilizing polymer network, mainly through elastic interactions between the liquid crystal and the network. The morphology of the polymer in turn depends on the preparation conditions during polymerization. By using the fractal dimension as a means to describe the polymer morphology, we present scaling relations that quantitatively link the electro‐optic response of polymer‐stabilized cholesteric textures to the preparation conditions and the resulting network structure of the device. The validity of this description is demonstrated for several preparation series, including variation of curing temperature, UV intensity, time of UV irradiation, and photo‐initiator concentration. Additionally, some non‐fractal scaling relations are discussed with respect to sandwich cell gap and wavelength of the probing light. From the scaling relations, essential properties of PSLC devices can be predicted for varying preparation conditions over a wide range of parameters.
Composites of Polyacrylonitrile and Multiwalled Carbon Nanotubes Prepared by Gelation/Crystallization from Solution
Authors: Koganemaru A. , Bin Y. , Agari Y. , Matsuo M. 
Published: September 2004

AbstractComposite films of polyacrylonitrile (PAN) and multiwalled carbon nanotubes (MWNTs) have been prepared by gelation/crystallization from solution. The contents of MWNTs were 5–10 wt.‐%, measured against PAN. The electrical and mechanical properties have been studied in comparison with those of the homopolymer PAN films prepared from the same method. Furthermore, stabilization and the carbonization have been carried out by using the drawn PAN–MWNTs as a new precursor to prepare carbon films with a cross‐sectional area much larger than that of a commercial carbon fiber (&&num;62; 3000 times). The MWNTs within the PAN matrix promote the formation of a condensed aromatic ladder structure during the stabilization process and play an important role in preparing PAN‐based carbon material with high carbon quality and high mechanical properties. When the stabilized composites with 10 wt.‐% MWNTs are carbonized at 1000 °C, the Young's modulus reaches 37.5 GPa, and the electrical conductivity reaches 102 S cm–1. The carbonized PAN homopolymer does not form an adequately robust bulk film for the mechanical properties to be measured.
Photoluminescence and Electron Paramagnetic Resonance of ZnO Tetrapod Structures
Authors: Djurišić A. B. , Choy W. C. H. , Roy V. A. L. , Leung Y. H. , Kwong C. Y. , Cheah K. W. , Gundu Rao T. K. , Chan W. K. , Fei Lui H. , Surya C. 
Published: September 2004

AbstractZnO tetrapod nanostructures have been prepared by the evaporation of Zn in air (no flow), dry and humid argon flow, and dry and humid nitrogen flow. Their properties have been investigated using scanning electron microscopy (SEM), X‐ray diffraction (XRD), photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopies (at different temperatures), and electron paramagnetic resonance (EPR) spectroscopy at –160 °C and room temperature. It is found that the fabrication conditions significantly influence the EPR and PL spectra obtained. While a g = 1.96 EPR signal is present in some of the samples, green PL emission can be observed from all the samples. Therefore, the green emission in our samples does not originate from the commonly assumed transition between a singly charged oxygen vacancy and a photoexcited hole [K. Vanheusden, C. H. Seager, W. L. Warren, D. R. Tallant, J. A. Voigt, Appl. Phys. Lett. 1996, 68, 403]. However, the green emission can be suppressed by coating the nanostructures with a surfactant for all fabrication conditions, which indicates that this emission originates from surface defects.
Controlled Growth and Properties of One‐Dimensional ZnO Nanostructures with Ce as Activator/Dopant
Authors: Cheng B. C. , Xiao Y. H. , Wu G. S. , Zhang L. D. 
Published: September 2004

AbstractA large amount of one‐dimensional (1D) Ce‐doped ZnO nanostructures with different morphologies has been successfully synthesized by annealing a polymeric precursor at various temperatures. The evolution of the morphologies and microstructures was investigated by field‐emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), and high‐resolution TEM (HRTEM). The results show that the morphologies vary drastically with increasing synthesis temperature and the photoluminescence (PL) of the products depends on both the synthesis and measurement temperatures. The CeO layer forms first and becomes a catalytic center for the ZnO growth. At a synthesis temperature lower than the boiling point of Zn, Zn and O atoms can stack epitaxially along the CeO catalytic layer and form a bicrystal nanobelt‐like structure with a trapezoid‐like end and a concave growth fault center. At a synthesis temperature higher than the boiling point of Zn, however, nanowires with an incommensurately modulated superstructure are obtained due to the high reaction rate and the formation of a periodic separation of the CeO layer. As for the room‐temperature PL of ZnO, the incorporation of donor Ce leads to the disappearance of the green band and the appearance of a purplish‐blue emission peak, whose position shifts towards the red and whose intensity decreases with increasing synthesis temperature. Analysis of this temperature‐dependent luminescence indicates that the purplish‐blue emission of nanobelts prepared at 850 °C originates from a donor‐bound exciton emission, and, contrary to the nanowires, it undergoes a change from an emission of the electron–hole plasma (EHP) to an emission of the donor‐bound exciton with decreasing measurement temperature.
Alignment of a Perylene‐Based Ionic Self‐Assembly Complex in Thermotropic and Lyotropic Liquid‐Crystalline Phases
Authors: Zakrevskyy Y. , Faul C. F. J. , Guan Y. , Stumpe J. 
Published: September 2004

AbstractThe thermotropic and lyotropic liquid‐crystalline (LC) phases of the ionic self‐assembled complex N,N′,‐bis(2‐(trimethylammonium)ethylene)‐perylene‐3,4,9,10‐tetracarboxyldiimide‐bis(2‐ethylhexyl)sulfosuccinate have been studied using polarizing microscopy, differential scanning calorimetry (DSC), and X‐ray scattering techniques. A two‐dimensional (2D) columnar thermotropic LC phase with π–π stacking of the perylene tectonic units and a lyotropic LC phase in dimethyl sulfoxide (DMSO) have been found. Different techniques have been applied to align both systems and included: surface interactions, electric and magnetic fields, shear force, and controlled domain formation at the LC–isotropic phase‐transition front (PTF). Characterization of the alignment in films has been performed using polarized UV‐vis spectroscopy and transmission null‐ellipsometry. The best results have been obtained for alignment of the material in a lyotropic phase by controlled domain formation at the PTF of the LC–isotropic phase transition. In this case, a dichroic ratio of 18 is achieved with packing of columns of perylenediimide tectons perpendicular to the PTF.
Improved Palladium and Nickel Catalysts Heterogenised on Oxidic Supports (Silica, MCM‐41, ITQ‐2, ITQ‐6)
Authors: González‐Arellano C. , Corma A. , Iglesias M. , Sánchez F. 
Published: September 2004

AbstractTwo series of solid catalysts in which a chiral palladium or nickel complex with Schiff bases as ligands have been immobilized on ordered mesoporous silica supports (MCM‐41), delaminated ITQ‐2, ITQ‐6 zeolites and amorphous silica have been prepared. Hydrogenation of alkenes and imines was studied with the homogeneous as well as with the counterpart heterogenized catalysts. The high accessibility introduced by the structure of the supports allows the preparation of highly efficient immobilized catalysts with TOFs of 1,000,000 h−1. A moderate acidity in the support increases the catalytic activity considerably, and the easy recoverable immobilized catalysts can duplicate the activity of the homogeneous analogues. No deactivation of the catalysts was observed after repeated recycling.
Carbene Rearrangements, 60.‡ Supramolecular Structure‐Reactivity Relationships: Photolysis of a Series of Aziadamantane@Cyclodextrin Inclusion Complexes in the Solid State
Authors: Krois Daniel , Brecker Lothar , Werner Andreas , Brinker Udo H. 
Published: September 2004

AbstractPhotolyses of the α‐, β‐ and γ‐cyclodextrin complexes of 2‐aziadamantane (1) in the solid state afforded markedly different product distributions, as determined by quantitative GC and HPLC analyses. The results are discussed with respect to the structures of the inclusion complexes.
Relationship between dopaminergic neurotransmission, alcoholism, and reward deficiency syndrome
Authors: Bowirrat Abdalla , Oscar‐Berman Marlene 
Published: September 2004

AbstractIn this review, we described the neural substrates underlying Reward Deficiency syndrome which, in turn, is posited to underlie alcohol dependency. Alcoholism is a complex, multifactorial disorder that results from the interplay between genetic and environmental factors. The D2 dopamine receptor (DRD2) has been associated with pleasure, and the DRD2 A1 allele has been referred to as a reward gene. Evidence suggests that there is a tripartite interaction involving dopamine receptor deficiency, a propensity to abuse alcohol, and reduced sensitivity to rewards. This interaction relies heavily on genetic characteristics of the individual, with certain ethnic groups having a greater tendency toward alcoholism than others. The DRD2 has been one of the most widely studied in neuropsychiatric disorders in general, and in alcoholism and other addictions in particular. The dopamine D2 (DRD2) gene, and especially its allele TaqI A1 allele and its receptor, also may be involved in comorbid antisocial personality disorder symptoms, high novelty seeking, and related traits. The mesocorticolimbic dopaminergic pathway system plays an especially important role in mediating reinforcement by abused drugs, and it may be a common denominator for addictions such as alcoholism. When the mesocorticolimbic dopamine reward system dysfunctions (perhaps caused by certain genetic variants), the end result is Reward Deficiency syndrome and subsequent drug‐seeking behaviors. Reward Deficiency syndrome refers to the breakdown of the reward cascade, and resultant aberrant conduct, due to genetic and environmental influences. Alcohol and other drugs of abuse, as well as most positive reinforcers, cause activation and neuronal release of brain dopamine, which can decrease negative feelings and satisfy abnormal cravings. A deficiency or absence of DRD2 receptors then predisposes individuals to a high risk for multiple addictive, impulsive, and compulsive behaviors. Although other neurotransmitters (e.g., glutamate, gamma‐aminobutyric acid (GABA), and serotonin) may be important in determining the rewarding and stimulating effects of ethanol, dopamine may be critical for initiating drug use and for reinstating drug use during protracted abstinence. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148‐7299:1/suppmat/index.html. © 2004 Wiley‐Liss, Inc.
Molecular genetic studies of ADHD: 1991 to 2004
Authors: Bobb Aaron J. , Castellanos F. Xavier , Addington Anjene M. , Rapoport Judith L. 
Published: September 2004

AbstractAttention deficit hyperactivity disorder (ADHD) is highly heritable but is likely a complex disorder involving multiple genes of moderate effect (Smalley [1997: Am J Hum Genet 60:1276–1282]). Over 100 studies have examined the genetics of ADHD by linkage or association, though no article has presented a comprehensive overview of all published reports. We reviewed all ADHD studies, including 3 genome‐wide linkage studies, and association studies of 94 polymorphisms in 33 candidate genes. To simplify comparisons across heterogeneous articles, demographics and comorbidity were ignored; analyses of subtype and haplotypes were excluded; and only the most positive finding for each polymorphism in a study was reported. Thirty‐six percent of all findings were positive (P ≤ 0.05), 17% were trends (0.05 < P ≤ 0.15), and 47% were negative (P > 0.15). Studies utilizing dimensional measures of ADHD tended to result in higher rates of positive findings than those using categorical diagnoses (χ2 = 5.6, P = 0.018), and case‐control studies tended to result in higher rates of positive findings than family‐based studies (χ2 = 18.8, P < 0.001). However, for either dichotomy, no significant difference remained when analyzing only studies using both methods within the same population and polymorphism. Evidence for association exists for four genes in ADHD: the dopamine D4 and D5 receptors, and the dopamine and serotonin transporters; others are promising but need further replication, including the dopamine D2 and serotonin 2A receptors. All candidate gene approaches continue to face the problem of relatively low power, given modest odds ratios for even the best replicated genes. © 2004 Wiley‐Liss, Inc.
Identification of a novel 45 repeat unstable allele associated with a disease phenotype at the MJD1/SCA3 locus
Authors: Padiath Quasar Saleem , Srivastava Achal Kumar , Roy Sanghmitra , Jain Satish , Brahmachari Samir Kumar 
Published: September 2004

AbstractWe report a three generation Indian pedigree with the proband having 45 repeats at the Machado Joseph Disease (MJD)/spinocerebellar ataxia 3 (SCA3) disease locus. The proband exhibited clinical features of SCA and showed signs of cerebellar and brainstem atrophy on the MRI scan. The 45 repeat allele was unstable upon inter‐generational transmission and was associated with a haplotype found in the majority of MJD/SCA3 patients from around the world. This is the smallest unstable allele reported till date at the MJD/SCA3 locus and may greatly reduce the gap between normal and pathological repeat ranges. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148‐7299:1/suppmat/index.html. © 2004 Wiley‐Liss, Inc.
Relationship of MAO‐A promoter (u‐VNTR) and COMT (V158M) gene polymorphisms to CSF monoamine metabolites levels in a psychiatric sample of caucasians: A preliminary report
Authors: Zalsman Gil , Huang Yung‐yu , Harkavy‐Friedman Jill M. , Oquendo Maria A. , Ellis Steven P. , Mann J. John 
Published: September 2004

AbstractMonoamine oxidase A gene promoter (MAOA‐uVNTR) and catechol‐O‐methyltransferase V158M (COMT‐V158M) gene functional polymorphisms are reported to be associated with impulsive‐aggression, but a biological intermediate effect remains to be determined. This study assessed the association of these polymorphisms with cerebrospinal fluid (CSF) monoamine metabolites as endophenotypes. Ninety‐eight Caucasian psychiatric subjects were assessed for Axis I and II diagnosis. Subjects were genotyped for the functional polymorphisms, MAOA‐uVNTR and COMT‐V158M. CSF was obtained by lumbar puncture. Relationships of the two polymorphism to monoamine metabolites: HVA, 5‐HIAA, and MHPG were examined. The higher‐expressing MAOA‐uVNTR genotype was associated with higher CSF‐HVA levels in males only (n = 46) (195.80 pmol/ml, SD = 61.64 vs. 161.13, SD = 50.23, respectively; P = 0.042). No association was found with diagnosis. COMT‐V158M had no association with CSF monoamine metabolites. The association of MAOA‐uVNTR with dopaminergic activity in males is a preliminary finding that needs to be replicated in a larger sample of Caucasian males and relationships sought with clinical phenotypes. This article contains supplementary material, which may be viewed at the American Journal of Medical Genetics website at http://www.interscience.wiley.com/jpages/0148‐7299:1/suppmat/index.html. © 2004 Wiley‐Liss, Inc.
Subcutaneous octreotide in cluster headache: Randomized placebo‐controlled double‐blind crossover study
Authors: Matharu Manjit S. , Levy Miles J. , Meeran Karim , Goadsby Peter J. 
Published: September 2004

AbstractCurrent practical evidence‐based acute treatments of cluster headache are limited to subcutaneous and intranasal formulations of sumatriptan, and oxygen. Two small randomized, double‐blind trials suggested efficacy of somatostatin in cluster headache. We sought to determine whether octreotide, a somatostatin analog, is effective in the abortive treatment of acute cluster headache. Patients with episodic and chronic cluster headache, as defined by the International Headache Society, were recruited to a double‐blind placebo‐controlled crossover study. Patients were instructed to treat two attacks of at least moderate pain severity, with at least a 24‐hour break, using subcutaneous octreotide μg or matching placebo. The primary end point was the headache response defined as very severe, severe, or moderate pain becomes mild or nil, at 30 minutes. The primary end point was examined using a multilevel analysis approach. A total of 57 patients were recruited of whom 46 provided efficacy data on attacks treated with octreotide and 45 with placebo. The headache response rate with subcutaneous octreotide was 52%, whereas that with placebo was 36%. Modeling the treatment outcome as a binomial where response was determined by treatment, using the patient as the level 2 variable, and considering period effect, sex, and cluster headache type as other variables of interest, we found that the effect of subcutaneous octreotide 100μg was significantly superior to placebo (p < 0.01). Subcutaneous octreotide 100μg is effective in the acute treatment of cluster headache when compared with placebo. Nonvasconstrictor treatment of acute cluster headache is possible. Ann Neurol 2004
Pulse‐synchronous eye oscillations revealing bone superior canal dehiscence
Authors: Tilikete Caroline , Krolak‐Salmon Pierre , Truy Eric , Vighetto Alain 
Published: September 2004

AbstractSuperior canal dehiscence syndrome is a newly recognized syndrome characterized by vertigo and nystagmus induced by sound (Tullio phenomenon) or changes of middle ear (Hennebert sign) or intracranial pressure. We report on a patient with bilateral superior canal dehiscence syndrome who presented with unusual manifestations including pulse‐synchronous vertical pendular nystagmus and Valsalva‐induced, up and counterclockwise‐beating jerk nystagmus. These unusual symptoms may be a clue to a better understanding of the pathophysiology of superior canal dehiscence syndrome. Abnormal communication between the inner ears and the intracranial space may explain the vertical pendular and pulse‐synchronous nystagmus, modulated by increased intracranial pressure. Ann Neurol 2004;56:556–560
The acute effects of glycemic control on axonal excitability in human diabetics
Authors: Kitano Yukiko , Kuwabara Satoshi , Misawa Sonoko , Ogawara Kazue , Kanai Kazuaki , Kikkawa Yuriko , Yagui Kazuo , Hattori Takamichi 
Published: September 2004

AbstractIn diabetic nerves, the activation of the polyol pathway and a resulting decrease in Na+‐K+ ATPase activity lead to intra‐axonal Na+ accumulation and a smaller Na+ gradient across the axolemma than normal. To investigate whether glycemic control is associated with acutely reversible changes in axonal excitability and Na+ conductance, we measured the multiple excitability indices (strength‐duration time constant, rheobase, refractoriness, and refractory period) of the median motor axons of 21 diabetic patients before and after intensive insulin treatment. Within 4 weeks after treatment was begun, there was a significant improvement in nerve conduction velocities, associated with increased strength‐duration time constant, decreased rheobase, increased refractoriness, and prolonged refractory periods. Assuming that the strength‐duration time constant partly reflects persistent Na+ conductance, and that refractoriness/refractory periods depend on inactivation of transient Na+ channels caused by prior depolarization (the influx of Na+), the patterns of changes in these indices may reflect a reduced trans‐axonal Na+ gradient during hyperglycemia and its restoration by glycemic control in diabetic patients. Measurement of the excitability indices could provide new insights into the pathophysiology of human diabetic neuropathy. Ann Neurol 2004;56:462–467
Insulin signaling pathways in cortical dysplasia and TSC‐tubers: Tissue microarray analysis
Authors: Miyata Hajime , Chiang Alexander C. Y. , Vinters Harry V. 
Published: September 2004

AbstractTo evaluate the possible roles of the Akt/PKB‐mTOR‐p70S6K‐S6 and cap‐dependent translation (eIF4G) pathways in the pathogenesis of tuberous sclerosis complex (TSC)–associated cortical tubers and focal cortical dysplasia (FCD), we performed qualitative and semiquantitative immunohistochemical evaluation on surgically resected corticectomy specimens to detect phosphorylated molecules as activated downstream targets of the signaling pathways. A tissue microarray paraffin block was constructed from 63 archival specimens of surgically resected TSC tubers, FCDs with balloon cells, cortical dysplasia without balloon cells, and histologically normal–appearing neocortex obtained from cases with Rasmussen encephalitis, cystic–gliotic encephalopathy, and temporal lobe epilepsy. Abnormal neuroglial cells were positive for phospho‐S6 and phospho‐eIF4G with various staining intensities in FCDs and TSC tubers. Both proteins were much less abundantly expressed in normal‐appearing neocortex. Phospho‐mTOR expression was observed in neurons in all groups. The expression of phospho‐S6 and phospho‐eIF4G was associated with dysplastic lesions (p < 0.05), and the cytoplasmic phospho‐p70S6K expression was most specific for and abundant in TSC tubers and much less prominent in other groups (p < 0.01). These results suggest that constitutive activation of cytoplasmic p70S6K plays a pivotal role in the pathogenesis of TSC tubers and that FCDs possess a distinct mechanism for activation of S6 and eIF4G. Ann Neurol 2004;56:510–519
A mutation in the HSN2 gene causes sensory neuropathy type II in a Lebanese family
Authors: Rivière Jean‐Baptiste , Verlaan Dominique J. , Shekarabi Masoud , Lafrenière Ronald G. , Bénard Mélanie , Der Kaloustian Vazken M. , Shbaklo Zuhayr , Rouleau Guy A. 
Published: September 2004

AbstractHereditary sensory and autonomic neuropathy (HSAN) type II is an autosomal recessive disorder clinically characterized by distal and proximal sensory loss that is caused by the reduction or absence of peripheral sensory nerves. Recently, a novel gene called HSN2 has been found to be the cause of HSAN type II in five families from Newfoundland and Quebec. Screening of this gene in an HSAN type II Lebanese family showed a 1bp deletion mutation found in a homozygous state in all affected individuals. This novel mutation supports the hypothesis that HSN2 is the causative gene for HSAN type II. Ann Neurol 2004;56:572–575
α‐Synuclein promoter confers susceptibility to Parkinson's disease
Authors: Pals Philippe , Lincoln Sarah , Manning Jonathan , Heckman Michael , Skipper Lisa , Hulihan Mary , Van den Broeck Marleen , De Pooter Tim , Cras Patrick , Crook Julia , Van Broeckhoven Christine , Farrer Matt J. 
Published: September 2004

AbstractFamilial Parkinson's disease (PD) has been linked to missense and genomic multiplication mutations of the α‐synuclein gene (SNCA). Genetic variability within SNCA has been implicated in idiopathic PD in many populations. We now confirm and extend these findings, within a Belgian sample, using a high‐resolution map of genetic markers across the SNCA locus. Our study implicates the SNCA promoter in susceptibility to PD, and more specifically defines a minimum promoter haplotype, spanning approximately 15.3kb of sequence, which is overrepresented in patients. Our findings represent a biomarker for PD and may have implications for patient diagnosis, longitudinal evaluation, and treatment. Ann Neurol 2004;56:591–595