bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Characterization of Electrochromic Polyamides with Well‐Defined Molecular Structures and Redox Properties
Authors: Gao J. , Liu D.‐G. , Sansiñena J.‐M. , Wang H.‐L. 
Published: June 2004

AbstractIn this paper we report the synthesis and characterization of a series of electrochromic polyamides (alternating copolymers). The synthesis proceeds via the condensation polymerization between amine‐capped oligoaniline and acyl chlorides such as isophthaloyl dichloride, terephthaloyl chloride, azelaoyl chloride, and dodecanedioyl dichloride. Both the orthogonal tert‐butoxycarbonyl (BOC) group on the oligoaniline segment and the non‐conjugated aromatic or aliphatic segment on the polymer backbone play a vital role in the formation of the final polyamides with good solubility in common organic solvents. We cast thin polyamide films from their chloroform solutions and studied their electrochemical behavior and spectroscopic properties. In contrast to the polyaniline, the copolymers bearing oligoaniline segments show four distinct oxidation states, which were fully characterized using IR and UV‐vis spectroscopy. The copolymer thin films also exhibit electrochromic behavior when a linear potential sweep is applied. Compared with the polyaniline, the polyamides adhere much more strongly to the indium tin oxide (ITO) coated glass and show no signs of delamination after hundreds of redox cycles in a hydrochloric acid solution. We believe that these factors make these novel polyamides very attractive as electrochromic materials.
The First Template‐Free Growth of Crystalline Silicon Microtubes
Authors: Hu J. , Bando Y. , Liu Z. , Zhan J. , Golberg D. 
Published: June 2004

AbstractA simple template‐free high‐temperature evaporation method was developed for the growth of crystalline Si microtubes for the first time. As‐grown Si microtubes were characterized using X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and room‐temperature photoluminescence. The lengths of the Si tubes can reach several hundreds of micrometers; some of them have lengths on the order of millimeters. Each tube has a uniform outer diameter along its entire length, and the typical outer diameter is ≈ 2–3 μm. Most of the tubes have a wall thickness of ≈ 400–500 nm, though a considerable number of them exhibit a very thin wall thickness of ≈ 50 nm. Room‐temperature photoluminescence measurement shows the as‐synthesized Si microtubes have two strong emission peaks centered at ≈ 589 nm and ≈ 617 nm and a weak emission peak centered at ≈ 455 nm. A possible mechanism for the formation of these Si tubes is proposed. We believe that the present discovery of the crystalline Si microtubes will promote further experimental studies on their physical properties and smart applications.
Porphyrin‐ and Fullerene‐Based Molecular Photovoltaic Devices
Authors: Imahori H. , Fukuzumi S. 
Published: June 2004

AbstractWe have developed a novel strategy for the construction of molecular photovoltaic devices where the porphyrins and fullerenes employed as building blocks are organized into nanostructured artificial photosynthetic systems by self‐assembly processes. Highly efficient photosynthetic energy‐ and electron‐transfer processes take place at gold and indium tin oxide (ITO) electrodes modified with self‐assembled monolayers of porphyrin‐ or fullerene linked systems. Porphyrins and fullerenes have also been assembled step by step to make large and uniform clusters on nanostructured semiconductor electrodes, which exhibit a high power‐conversion efficiency of close to 1 %. These results will provide valuable information on the design of donor–acceptor‐type molecular assemblies that can be tailored to construct highly efficient photovoltaic devices.
Organic Thin‐Film Transistors Based on Tolyl‐Substituted Oligothiophenes
Authors: Mohapatra S. , Holmes B. T. , Newman C. R. , Prendergast C. F. , Frisbie C. D. , Ward M. D. 
Published: June 2004

AbstractThin films based on the tolyl‐substituted oligothiophenes 5,5′′‐bis(4‐methylphenyl)‐2,2′:5′,2′′‐terthiophene (1), 5,5′′′‐bis(4‐methylphenyl)‐2,2′:5′,2′′:5′′,2′′′‐quaterthiophene (2) and 5,5′′′′‐bis(4‐methylphenyl)‐2,2′:5′,2′′:5′′,2′′′:5′′′,2′′′′‐quinqethiophene (3) exhibit hole‐transport behavior in a thin‐film transistor (TFT) configuration, with reasonable mobilities and high current on/off (Ion/Ioff) ratios. Powder X‐ray diffraction (PXRD) reveals that these films, grown by vacuum deposition onto the thermally grown silicon oxide surface of a TFT, are highly crystalline, a characteristic that can be attributed to the general tendency of phenyl groups to promote crystallinity. Atomic force microscopy (AFM) reveals that the films grow layer by layer to form large domains, with some basal domain areas approaching 1000 μm2. The PXRD and AFM data are consistent with an “end‐on” orientation of the molecules on the oxide substrate. Variable‐temperature current–voltage (I–V) measurements identified the activation regime for hole transport and revealed shallow level traps in thin films of 1 and 2, and both shallow and deep level traps in thin films of 3. The activation energies for thin films of 1, 2, and 3 were similar, with values of Ea = 121, 100, and 109 meV, respectively. The corresponding trap densities were Ntrap/Nv = 0.012, 0.023, and 0.094, where Ntrap is the number of trap states and Nv is the number of conduction states. The hole mobilities for the three compounds were similar (μ ≃ 0.03 cm2 V–1 s–1), and the Ion/Ioff ratios were comparable with the highest values reported for organic TFTs, with films of 2 approaching Ion/Ioff = 109 at room temperature.
Mitochondrial DNA and Alu insertions in a genetically peculiar population: The Ayoreo Indians of Bolivia and Paraguay
Authors: Dornelles C.L. , Battilana J. , Fagundes N.J.R. , Freitas L.B. , Bonatto S.L. , Salzano F.M. 
Published: June 2004

AbstractA total of 91 Ayoreo individuals previously studied for blood groups and protein markers, living in two Bolivian and one Paraguayan communities, were extensively investigated in relation to the hypervariable 1 segment of the control and eight coding regions of their mitochondrial DNA (mtDNA). They show an extremely reduced mtDNA variability, the observed haplotypes being classifiable in just two haplogroups (C and D). They were also variously studied in relation to six Alu insertions; in this case, however, the prevalences found did not depart markedly from those obtained in other populations of this ethnic group. To assess the Ayoreo position in relation to these populations, 11 other groups that had also been studied for these systems and for blood groups and proteins were selected. The dendrograms obtained with two of the three sets of markers showed distinct patterns, but the Ayoreo were placed in a central position in both the blood group + proteins and Alu insertions trees. Therefore, they are clearly distinct in relation to their mtDNA only, suggesting a strong founder effect and/or random loss of variability in this system. Am. J. Hum. Biol. 16:479–488, 2004.© 2004 Wiley‐Liss, Inc.
Growth of Han migrants at high altitude in central Asia
Authors: Weitz Charles A. , Garruto Ralph M. 
Published: June 2004

AbstractHan Chinese of low‐altitude descent have been living in Qinghai Province of Western China for at least two millennia. For most of this time they have lived at elevations under 2,500 m. However, during the last four decades an increasing number of Han have moved into high‐altitude towns at elevations over 3,000 m, and some above 4,000 m. There are now sufficient numbers of Han descendants who have been born and raised at high altitude to allow a comparison of their morphological and physiological growth patterns with low‐altitude Han to detect the effect of hypoxia. The field study reported here was conducted by collaborating Chinese and American researchers over a 6‐year period, and included 1,227 Han living at high altitude in Qinghai and at low altitude near Beijing. This study demonstrates that Han born and raised at high altitude are smaller and lighter than those at low altitude—particularly as children and adolescents. Slower growth at high altitude may be a consequence of hypoxia, but it also corresponds to poorer economic conditions in rural Qinghai Province, and thus may reflect nutritional inadequacies. Differences in altitude and/or nutrition do not seem to affect thorax dimensions, since, relative to stature, chest dimensions are similar at both high and low altitudes. Nevertheless, lung volumes are higher among Han at high altitude, possibly reflecting the influence of hypoxia on alveolar growth. The hematological values of Han growing up at 3,200 m are not different from those at low altitude—an unusual finding relative to other low‐altitude groups that may reflect population differences in response to hypoxia. At 3,800 m and 4,300 m, however, Han show elevated hemoglobin relative to Han at low altitude. Am. J. Hum. Biol. 16:405–419, 2004. Published 2004 Wiley‐Liss, Inc.
Kin‐structured migration: Causes and consequences
Authors: Fix Alan G. 
Published: June 2004

AbstractMigration among local populations classically has been seen as the principal process retarding genetic microdifferentiation. However, as Sewall Wright pointed out long ago, migration may also act as a random differentiating force. In fact, when migrants comprise a biological kin group, migration may be considered a component of genetic drift. The causes of kin‐structured migration (KSM) lie in the common, if not universal, tendency for kin to associate and cooperate. However, similar to genetic drift, KSM has its greatest effect in smaller populations and is most apparent in low‐density fission–fusion societies such as the Yanomamo of South America and the Semai of Malaysia, and less salient in higher density, low‐mobility populations such as those of the New Guinea Highlands. The evolutionary consequences of KSM begin with increased genetic variation among populations. Such intergroup variation provides a basis for group selection. The origin of larger‐scale geographic differentiation can arise from kin‐structured migrant groups colonizing new regions. Waves of colonizing kin‐structured founder groups may produce gene frequency clines, mimicking demic diffusion and natural selection. Finally, because kin structuring reduces the effective size of a population, it may be speculated that the extremely small effective size inferred for ancestral populations of Homo sapiens may be an artifact of kin‐structured demographically larger populations. Am. J. Hum. Biol. 16:387–394, 2004. © 2004 Wiley‐Liss, Inc.
Phenotype characterization and natural history of spondylothoracic dysplasia syndrome: A series of 27 new cases
Authors: Cornier A.S. , Ramírez N. , Arroyo S. , Acevedo J. , García L. , Carlo S. , Korf B. 
Published: June 2004

AbstractSpondylothoracic dysplasia (STD, MIM#277300) is an autosomal recessive disorder with high prevalence in the Puerto Rican population. It is generally regarded as a lethal condition. Since Jarcho and Levin described it in 1938, it has been referred to as spondylocostal dysplasia, costovertebral dysplasia, Jarcho–Levin syndrome and STD. We have prospectively characterized 27 patients with STD by detailed physical examination, pedigree analysis, thoracic CT scans, and pulmonary function tests (PFTs). Diagnoses were established using spinal radiographs and 3‐D reconstructive CT scans to demonstrate fusion of the ribs at the costo‐vertebral junction with a fan‐like (crab‐like) configuration of the thorax. Vertebral segmentation and formation defects were seen throughout the spine with a decrease in the number of vertebral bodies. Characteristic vertebral shape consisted of a decrease in antero‐posterior diameter and an increase in lateral length, giving the vertebra a sickle shape. Eight out of 18 prospectively follow patients died within the first 6 months of life, a 44% mortality rate. Cause of death was respiratory insufficiency secondary to pneumonia and pulmonary restriction. This is an important finding since the vast majority of STD syndrome patients cited in the medical literature have died in the newborn and early childhood periods. Age of the remaining patients ranged from 4 months to 47 years. This represents the largest collection of patients with STD reported and it has allowed us to determine a detailed phenotype. Given 56% survival at 6 months, we show that STD is not a lethal syndrome. © 2004 Wiley‐Liss, Inc.
Familial symptom domains in monozygotic siblings with autism
Authors: Kolevzon Alexander , Smith Christopher J. , Schmeidler James , Buxbaum Joseph D. , Silverman Jeremy M. 
Published: June 2004

AbstractAutism is characterized by a triad of symptom domains (impaired social interaction, communication deficits, and repetitive behaviors) that vary significantly in their clinical presentation across the population. Within families with more than one affected member, however, discrepant findings exist with regard to symptom variability. Reduced intrafamily variance is of particular importance because it supports an underlying model of genetic heterogeneity in the transmission of autism, and the identification of familial clinical subtypes can be used to select more homogeneous samples for linkage analysis in the future. This study examines whether there are specific features of autism that show decreased variance within 16 families with monozygotic siblings concordant for autism. Evidence for familiality was defined as significantly decreased variance of symptom levels within monozygotic siblingships as compared to between siblingships. Using regression analysis, we demonstrated significant aggregation of symptoms within monozygotic siblingships for two of the three main symptom domains in autism: impairments in communication and social interaction showed significant familiality. Within the repetitive behavior domain, only the categories of circumscribed interests and preoccupation with part‐objects showed reduced variance within siblingships. In addition, with the exception of a negative association between the social and behavior domains, partial correlation coefficients did not reveal significant associations between the levels of different symptom domains within families, suggesting that the levels of clinical features seen in autism may be a result of mainly independent genetic traits. Because of presumed genetic heterogeneity and the wide clinical variation seen in autism and other pervasive developmental disorders, selecting probands according to specific features known to show reduced variance within families may provide more homogeneous samples for genetic analysis and strengthen the power to detect the specific genes involved in autism. © 2004 Wiley‐Liss, Inc.
Nickel‐katalysierte reduktive Cyclisierungen und Kupplungen
Authors: Montgomery John 
Published: June 2004

AbstractSeit mehr als 50 Jahren wird Nickel als Katalysator in Cycloadditionen eingesetzt. Nickel‐katalysierte reduktive Kupplungen und Cyclisierungen sind hingegen erst in letzter Zeit intensiver untersucht worden, wobei inzwischen Mehrkomponenten‐Kupplungen von zwei oder mehr π‐Komponenten mit einem Hauptgruppen‐ oder Übergangsmetallreagens möglich sind. Mit diesen Methoden sind aus leicht verfügbaren Ausgangsmaterialien wichtige organische Strukturelemente zugänglich, unter anderem sind Verbindungen mit mehreren benachbarten Stereozentren, polycyclische Ringsysteme und Reaktionsprodukte mit komplexer Funktionalität aus einfachen, achiralen, acyclischen Vorstufen synthetisiert worden. Angesichts der Beteiligung von drei oder mehr reaktiven funktionellen Gruppen an der Katalyse sind zum Reaktionsmechanismus noch zahlreiche Fragen offen, etwa zur zeitlichen Abfolge der Bindungsbildungen und zur Natur reaktiver Intermediate. In diesem Aufsatz geben wir einen Überblick über neuere Fortschritte auf diesem sich schnell entwickelnden Gebiet.
Nickel‐Catalyzed Reductive Cyclizations and Couplings
Authors: Montgomery John 
Published: June 2004

AbstractFor over 50 years, nickel catalysis has been applied in cycloaddition processes. Nickel‐catalyzed reductive couplings and cyclizations, however, have only recently attracted a high level of interest. This group of new reactions allows a broad range of multicomponent couplings involving two or more π components with a main‐group or transition‐metal reagent. These processes allow the assembly of important organic substructures from widely available reaction components. Multiple contiguous stereocenters, polycyclic ring systems, and novel arrays of complex functionality may often be prepared from simple, achiral, acyclic precursors. With three or more reactive functional groups participating in the catalytic processes, many mechanistic questions abound, including the precise timing of bond constructions and the nature of reactive intermediates. This Review is thus aimed at providing a critical evaluation of recent progress in this rapidly developing field.
Parametermodell zur Bestimmung des direkten Anteils des Tageslichtquotienten in Räumen mit Oberlichtern
Authors: von Grabe Jörg 
Published: June 2004

AbstractIm folgenden Beitrag wird ein Parametermodell für die Berechnung des direkten Anteils des Tageslichtquotienten in Räumen mit diffus transmittierenden Fensterflächen (Strahlflächen) polygonaler Form dargestellt. Mit Hilfe dieses Modells lassen sich die unten beschriebenen Parameter anhand der Anforderungen an die Höhe und an die Gleichmäßigkeit der Beleuchtungsstärke im Innenraum optimieren, ohne auf aufwendige Raytracing‐Modelle zurückgreifen zu müssen. Als Grundlage der Berechnungsgleichung werden zunächst die erforderlichen Grundgrößen der Lichttechnik erläutert. Anschließend wird auf der Basis des photometrischen Entfernungsgesetzes eine Gleichung entwickelt, die das Verhältnis der Beleuchtungsstärke auf der Außenseite der Strahlfläche zur Beleuchtungsstärke auf der Empfängerfläche beschreibt. Für den Spezialfall der rechteckigen Strahlfläche wird dabei die Neigung der strahlenden Fläche durch die Drehung des Koordinatensystems in einer der Hauptachsen und die entsprechende Anpassung der Integrationsgrenzen berücksichtigt. Aus den entwickelten Gleichungen kann abschließend das Verhältnis zwischen der äußeren horizontalen Beleuchtungsstärke und der Beleuchtungsstärke auf der geneigten Fläche abgeleitet und somit der direkte Anteil des Tageslichtquotienten bestimmt werden.
Untersuchungen zum thermisch induzierten Luftwechselpotential von Kippfenstern
Authors: Hall Monika 
Published: June 2004

AbstractDie sogenannte natürliche Lüftung — Lüftung infolge Temperatur‐ und Windeinwirkung über geöffnete Türen und Fenster — ist auch heute noch in Wohngebäuden die verbreitetste Form des Lüftens. Da die Lüftung über Kippfenster eine übliche Form des Lüftens ist, ist die Kenntnis des Luftwechsels über Kippfenster von großem Interesse. Der Vergleich von Ansätzen aus der Literatur zur Berechnung des Luftwechsels über Kippfenster zeigt, daß diese unter Verwendung gleicher Randbedingungen zu unterschiedlichen Ergebnissen führen. Aus diesem Grund wird aus eigenen Messungen ein Modellansatz abgeleitet, der die einseitige, thermisch induzierte Kippfensterlüftung besser beschreibt und gleichzeitig das Vorhandensein einer Laibung und/oder einer Heizung berücksichtigt.
5000 Jahre Biotechnologie: Vom Wein zum Penicillin
Authors: Ulber Roland , Soyez Konrad 
Published: June 2004

AbstractDie Biotechnologie begleitet den Menschen seit Jahrtausenden. Sie war lange eher unbeachtet empirisch immer weiter entwickelt worden und hat so stetig zur gesellschaftlichen Entwicklung des Menschen beigetragen. In Zeiten materieller Engpässe wurden in rasantem Tempo biotechnologische Prozesse entwickelt. Beispiele sind die Verfahren zur Herstellung von Aceton, Glycerin oder Butanol während des Ersten Weltkrieges und die Entwicklung der Antibiotika während des Zweiten Weltkrieges.
Lackarbeiten aus Myanmar: Vom Baumsaft zum Kunsthandwerk
Authors: Golloch Alfred , Sein Myint Myint 
Published: June 2004

AbstractDekorative Lackwaren sind ein wichtiges Produkt des Kunsthandwerks in Myanmar (Birma). Ihre Herstellung basiert auf dem von Lackbäumen gebildeten Saft, der nach alten Verfahren manuell verarbeitet wird. Der Lack enthält als Hauptkomponenten Brenzcatechine mit langkettigen Substituenten, die eine oder mehrere Doppelbindungen enthalten. Unter Mitwirkung des Enzyms Laccase verläuft die oxidative Polymerisation der Brenzcatechine. Die Bildung des Lackfilms kann aber nach verschiedenen Mechanismen erfolgen.
Ionen an der Luft/Wasser‐Grenzfläche
Authors: Jaenicke Lothar 
Published: June 2004

AbstractDie gefühlsmäßige und auch von schlichten Gibbsschen Phasenregel‐ Thermodynamikern ohne „computerhinterfragte”︁ Experimentalkritik gestützte Vorstellung ist, dass im Luftraum über einer wässrigen Lösung stark dissoziierter Salze, wie NaCl etc., keine Ionen zu finden sind, sondern nur in der Wasserphase, denn die Änderung der Oberflächenspannung geht der Salzkonzentration proportional.
Die Lakritzschnecke
Authors: Roth Klaus 
Published: June 2004

AbstractDas genüssliche Abrollen und stückweise Vernaschen einer Lakritzschnecke ist der schmackhafteste Weg, die eigene Zunge tiefschwarz zu färben. Aber Lakritze kann noch mehr: „Ein schwarzer Mund ist dem Magen gesund”︁, mit diesem Motto warb die Firma Haribo Ende der Fünfziger Jahre um die Gunst der Käufer, und tatsächlich sind die Wurzeln des Süßholzes, aus der Lakritze gewonnen wird, eine der ältesten Drogen. Im Folgenden wollen wir die Chemie dieser gesunden Köstlichkeit näher ergründen.
Entschwefelung von Dieselkraftstoff
Authors: Uerdingen Mark 
Published: June 2004

AbstractDie Entschwefelung von Dieselöl erfährt derzeit eine hohe Aufmerksamkeit: Aufgrund von Umweltschutzbestimmungen müssen Kraftstoffe praktisch vollständig entschwefelt werden, da beim Verbrennen schwefelhaltiger Kraftstoffe unerwünschtes Schwefeldioxid entsteht (Stichwort „Saurer Regen”︁). Darüber hinaus sollen Kraftstoffe zukünftig aber vor allem deshalb bis auf wenige ppm Schwefel tiefenentschwefelt werden, um neue Motor‐ und Katalysatorkonzepte zu realisieren, die die CO‐, NOx‐ und Partikelemissionen und den Kraftstoffverbrauch noch weiter vermindern.
A study of transfer switching for the purpose of fault detection in FRIENDS
Authors: Suzuki Toshihiro , Hara Ryoichi , Kita Hiroyuki , Tanaka Eiichi , Hasegawa Jun , Iyoda Isao 
Published: June 2004

AbstractThe authors have proposed a new concept of a distribution system “Flexible, Reliable and Intelligent ENergy Delivery System (FRIENDS)” with intent to solve imminent operating problems faced by utilities in providing their customers with reliable supply of power at several levels of quality. The main idea of FRIENDS is to introduce new facilities, so‐called Quality Control Centers (QCCs), which are installed very close to the customers for the purpose of implementing multiple functions, such as Customized Power Quality Service. In addition, these QCCs form a network for energy and information transmission at a level below distribution substations. QCCs make it possible to frequently change configuration of the network depending on the system and load conditions. These frequent reconfigurations of the network require fast and reliable Transfer Switching in the QCCs to ease an effect on customers. The reconfiguration for the purpose of fault area isolation also requires a fast Fault Detection feature.This paper presents a new method for controlling Transfer Switching and a method of Fault Detection in order to realize a fast and reliable reconfiguration of QCC network in a normal state, as well as under fault conditions. This paper also analyzes the methods in terms of instantaneous values calculated by PSCAD/EMTDC. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 148(3): 25–35, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10298