bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparative study of cyclotron development at Cambridge and Liverpool in the 1930s
Authors: HINOKAWA SHIZUE 
Published: March 2004

ABSTRACT:
This article describes the process of cyclotron development in Britain in the 1930s by focusing on the relationships between John D. Cockcroft, James Chadwick, and the Metropolitan-Vickers Electrical Company, Ltd. There is a difference of about one year in the completion dates of the cyclotrons built by Cockcroft at Cambridge University's Cavendish Laboratory and by Chadwick at the University of Liverpool. This time discrepancy seems to be a consequence of the differing relationships the two men had with Met-Vick. Analysis of British cyclotron development points to three major changes that took place in scientific research: the emergence in university laboratories of researchers specializing in developing experimental instruments; alterations in the relationship between university research laboratories and companies; and the need for special funding sources to enable university laboratories to construct experimental instruments.
Chemistry in the Académie Royale des Sciences
Authors: HOLMES FREDERIC LAWRENCE 
Published: March 2004

ABSTRACT:
In the received history, chemistry began to transform from cookery to science toward the end of the 17th century with the introduction of sustained systematic experiment, color indicators, and the mechanical philosophy. Robert Boyle is usually considered the chief promoter of these improvements. In fact, the mechanical philosophy played a marginal part in the development of chemistry during Boyle's time and he was too eager an alchemical adept to establish the cooperative enterprise that precipitated modern chemistry. While Boyle sought the philosopher's stone, members of the Paris Academy of Sciences set the course of modern chemistry by developing a style of thorough, repeated, systematic experimentation and accurate measurement that resemble the practices that historians customarily credit to the late 18th century. The present paper makes this case by reconstructing the Academy's program of experiments to determine the constituents of chemical “mixts,” mainly parts of plants, as recorded in the laboratory notebooks of Claude Bourdelin. These experiments typically employed maceration or a similar technique to “loosen” the ingredients of the substance under investigation followed by distillation at various temperatures. The academicians tested the several fractions of distillate thus produced with many reagents, including color indicators of acidity. Some of the preliminary steps lasted for weeks, and some of the distillations for days. To reassure themselves that their procedures did not destroy or discard important constituents, they weighed both raw materials and end products and totted up the sum in a manner worthy of Lavoisier.
From explanation to description: Molecular and phenomenological theories of piezoelectricity
Authors: KATZIR SHAUL 
Published: March 2004

ABSTRACT:
The second half of the 19th century saw the rise of new corpuscular theories in physics. Piezoelectricity, discovered in 1880, underwent a development reverse to that of most fields of physics. The first molecular theories were soon replaced by a continuum-phenomeno-logical theory, which guided most research in the field, while, at the same time, physicists continued to propose molecular models. This article studies the reasons for the peculiar development of piezoelectric theory, through a close look at the models suggested and the developments in the field. It argues that the transition originated in a failure of the molecular model to account for new experimental results. Furthermore, later explanatory theories remained speculations, since they failed to derive any relations left unaccounted for by the phenomenological theory and since their basic premises were doubtful. Protagonists also raised general claims about the necessity of a phenomenological theory. Yet they did not derive their position from a doctrinal antagonism to molecular explanation. The same physicists studied both the secure phenomenological theory and speculative explanation simultaneously. They advanced in two mostly separated kinds of researches: molecular-atomistic and phenomenological-positivistic. Nevertheless, the separation between these approaches was not complete. This suggests that physicists embodied the same persona in elaborating “positivistic” theory as in elaborating “realistic” molecular theory.
Magnetic Fields as an Investigation Technique and Manipulation Tool for Phthalocyanine Molecular Aggregates
Authors: Boamfa M. I. , Christianen P. C. M. , Engelkamp H. , Nolte R. J. M. , Maan J. C. 
Published: March 2004

AbstractA polarized absorption spectroscopy (PAS) study of molecular aggregate solutions of phthalocyanine molecules in high magnetic fields is presented. We show that a magnetic field can induce macroscopic ordering of molecular aggregates (MAs), in a clean, non‐contact method, which is well suited for MA manipulation. We also demonstrate that magnetic‐field‐induced alignment in combination with PAS can be used to determine the MA size and the precise position of the absorption lines in concentrated solutions, as well as probe interaggregate interactions.
Nanohomojunction (GaN) and Nanoheterojunction (InN) Nanorods on One‐Dimensional GaN Nanowire Substrates
Authors: Lan Z. H. , Liang C. H. , Hsu C. W. , Wu C. T. , Lin H. M. , Dhara S. , Chen K. H. , Chen L. C. , Chen C. C. 
Published: March 2004

AbstractThe formation of homojunctions and heterojunctions on two‐dimensional (2D) substrates plays a key role in the device performance of thin films. Accelerating the progress of device fabrication in nanowires (NWs) also necessitates a similar understanding in the one‐dimensional (1D) system. Nanohomojunction (GaN on GaN) and nanoheterojunction (InN on GaN) nanorods (NRs) were formed in a two‐step growth process by a vapor–liquid–solid (VLS) mechanism. Ga2O3 nanoribbons were formed using Ni as catalyst in a chemical vapor deposition (CVD) technique and then completely converted to GaN NWs with NH3 as reactant gas. An Au catalyst is used in the second step of the VLS process to grow GaN and InN NRs on GaN NWs using CVD techniques. A morphological study showed the formation of nanobrushes with different structural symmetries and sub‐symmetries in both homogeneous and heterogeneous systems. Structural characterizations showed nearly defect‐free growth of nanohomojunction (GaN) and nanoheterojunction (InN) NRs on 1D GaN NW substrates.
Panchromatic Chromophore Mixtures in an AlPO4‐5 Molecular Sieve: Spatial Separation Effects and Energy Transfer Cascades
Authors: Ganschow M. , Hellriegel C. , Kneuper E. , Wark M. , Thiel C. , Schulz‐Ekloff G. , Bräuchle C. , Wöhrle D. 
Published: March 2004

AbstractDye‐loaded AlPO4‐5 single crystals were prepared by microwave‐assisted hydrothermal synthesis from a batch, containing a mixture of three chromophores (Coumarin 40, Rhodamine BE50, and Oxazine 1) differing in their absorption range, molecular dimensions, and solubilities. Confocal fluorescence images reveal a spatial separation effect of the dye molecules, where the slimmer, more‐soluble dye molecule (Coumarin 40) is uniformly distributed in the body of the single crystal, and the bulky and/or less‐soluble ones (Rhodamine BE50, Oxazine 1) are situated in distinct domains. Visible spectra show good panchromatic absorption of visible light. Fluorescence lifetime measurements indicate the presence of an energy transfer cascade of the entirely fixed dye molecules from Coumarin 40 to Oxazine 1. The transfer mechanism is predominantly radiative.
Charge‐Transport Behavior in Aligned Carbon Nanotubes: A Quantum‐Chemical Investigation
Authors: Yang X. , Chen L.‐P. , Shuai Z.‐G. , Liu Y.‐Q. , Zhu D.‐B. 
Published: March 2004

AbstractCorrelated quantum‐chemical calculations are applied to analyze the amplitude of the electronic‐transfer integrals that describe charge transport in interacting carbon nanotubes (CNTs) by investigating the influences of: i) the relative positions of the CNTs, ii) the size of the CNTs, and iii) their chemical impurities. Our results indicate that the mobility of the charge carrier is extremely sensitive to the molecular packing and the presence of chemical impurities. The largest splitting for the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels is in the case of perfectly cofacial conformations where hexagons face hexagons in the dimer structure. We found that the diameter of the CNT determines the type of transporting carrier: for CNTs with large diameters hole transport dominates, while for thin CNTs electron transport dominates. In general, the carrier mobility for the perfect CNTs (n ≥ 3) is less pronounced than that of C60 due to their relatively small strain. B‐ and N‐doped CNTs exhibit considerably larger mobilities owing to the possibility of metallic behavior. These results provide a plausible explanation for the high mobility found experimentally in a field‐effect transistor (FET) made from a large‐area, well‐aligned CNT array. In addition, these hole‐rich and electron‐rich dopants imply potential applications in nanoelectronics.
Photogeneration of High Pretilt Angles of Nematic Liquid Crystals by Non‐Polarized Light Irradiation of Azobenzene‐Containing Polymer Films
Authors: Furumi S. , Ichimura K. 
Published: March 2004

AbstractA vertical‐alignment (VA) cell of nematic liquid crystals (LCs) was prepared using photoirradiated thin films of a poly(methacrylate) with mesogenic moieties of 4‐trifluoromethoxyazobenzene as the side chains. Optical anisotropy was generated by oblique irradiation of the azobenzene‐containing polymer films with non‐polarized UV light, followed by annealing treatment to enhance the photodichroism, which displayed thermal stability. The combination of oblique exposure to non‐polarized UV light and subsequent annealing treatment brought about high pretilt angles of nematic LCs so that a photoaligned VA LC cell was fabricated. The photopatterned LC cell exhibited electro‐optical properties with excellent optical quality when a voltage was applied even after heating at 100 °C for several hours.
High‐Contrast Electrochromism and Controllable Dissolution of Assembled Prussian Blue/Polymer Nanocomposites
Authors: DeLongchamp D. M. , Hammond P. T. 
Published: March 2004

AbstractTo maintain the momentum and impact of the field, assembled materials systems must increasingly incorporate broad functionality to meet real‐world applications. Here we describe nanocomposite films of specially synthesized inorganic Prussian blue (PB) nanoparticles and linear poly(ethylene imine) (LPEI) that possess the unusual functional combination of high‐performance electrochromism for displays and controllable dissolution for drug delivery. Fabrication using layer‐by‐layer (LBL) assembly was followed by spectroelectrochemical characterization, allowing a full composition determination rarely achieved for LBL films. The electrochromic performance of thick LPEI/PB nanocomposites most relevant to applications surpassed that of inorganic PB films with competitive switching speed and superior contrast. Oxidation beyond the primary electrochromic transition removes nanoparticle ionization and can controllably dissolve the films. Because PB is non‐toxic we suggest this mechanism for controlled in‐vivo drug delivery. The performance and multifunctional quality of these nanocomposites promise a strong impact on flexible displays, electrochromic windows, and even biomedical devices.
Molecules with Linear π‐Conjugated Pathways between All Substituents: Omniconjugation
Authors: van der Veen M. H. , Rispens M. T. , Jonkman H. T. , Hummelen J. C. 
Published: March 2004

AbstractIn this paper, omniconjugation is introduced as a topological phenomenon in π‐conjugated systems. Omniconjugated molecules are defined by the fact that they provide direct and fully π‐conjugated pathways between all substituents attached to them. Surprisingly, until now such topologies have never been explicitly recognized or investigated from this point of view. A topological design scheme is presented as a tool, which enables for the systematic construction of this novel class of π‐electron molecular structures. Molecular building blocks with three or more connection points to the external moieties are proposed, which for the first time allows for the interconnection of many functional entities in a fully conjugated manner. In being truly conjugated, these pathways are expected to provide high transmission probabilities for holes and/or electrons. Omniconjugated structures may play an important role in the design of complex electronic circuitry based on organic molecules. On a larger scale, they may also give rise to special material properties. Although omniconjugation is based on a valence‐bond description of the system, it is shown that our concept is in good agreement with results obtained from a molecular‐orbital description of the electron probability distribution in the frontier orbitals.
Morphological Control of Nanoporous Films by the Use of Functionalized Cyclodextrins as Porogens
Authors: Yim J‐H. , Seon J‐B. , Jeong H‐D. , Pu L. S. , Baklanov M. R. , Gidley D. W. 
Published: March 2004

AbstractPorous cyclic silsesquioxane (CSSQ) thin films containing nanopores (∼ 2 nm) with low dielectric constant (k &&num;60; 2.2), have been prepared by using various kinds of cyclodextrin (CD) derivatives as porogenic materials. The pore structure, including average pore size and interconnectivity, can be controlled by changing the functional groups of the cyclodextrin derivatives. The pore structure is found to be strongly related to the affinity of the functional groups between CD molecules. The electrical and mechanical properties of the porous thin films were monitored in order to determine the relationship between the pore structure and film properties. The mechanical properties of porous low‐k thin films (total porosity ∼ 30 %) prepared with CD derivatives are found to be correlated with the pore interconnection length. The longer the deduced interconnection length in the thin film, the worse the mechanical properties (such as hardness and modulus) of the thin film, even though the porogen‐induced pore diameters are very small (∼ 2 nm).
Synthesis and Room‐Temperature Ultraviolet Photoluminescence Properties of Zirconia Nanowires
Authors: Cao H. Q. , Qiu X. Q. , Luo B. , Liang Y. , Zhang Y. H. , Tan R. Q. , Zhao M. J. , Zhu Q. M. 
Published: March 2004

AbstractThis paper reports the synthesis of tetragonal zirconia nanowires using template method. An as‐prepared sample was characterized by scanning and transmission electron microscopy. It was found that the as‐prepared materials were tetragonal zirconia nanowires with average diameters of ca. 80 nm and length of over 10 μm. The Raman spectrum showed peaks at 120, 461, and 629 cm–1, which are attributed to the Eg, Eg, and B1g phonon modes of the tetragonal zirconia structure, respectively. The UV‐vis absorption spectrum showed an absorption peak at 232.5 nm (5.33 eV in photon energy). Photoluminescence (PL) spectra of zirconia nanowires showed a strong emission peak at ca. 388 nm at room temperature, which is attributed to the ionized oxygen vacancy in the zirconia nanowires system.
Morphology‐Controlled Growth of Large‐Area Two‐Dimensional Ordered Pore Arrays
Authors: Sun F. , Cai W. , Li Y. , Cao B. , Lei Y. , Zhang L. 
Published: March 2004

AbstractA solution‐dipping template strategy for large‐area synthesis of morphology‐controlled, ordered pore arrays is reported. The morphology of the pore array can easily be controlled by concentration of the precursor solution and treatment conditions. With decrease of the concentration from a high level to a very low level nanostructured complex (pore–hole, and pore–particle) arrays, through‐pore arrays, and even ring arrays can, in turn, be obtained. The pore size is adjustable over a large range by changing the diameter of the template's latex spheres. This synthesis route is universal and can be used for various metals, semiconductors and compounds on any substrate. Such structures may be useful in applications such as energy storage or conversion, especially in integrated next‐generation nanophotonics devices, and biomolecular labeling and identification.
Mechanical and Structural Properties of BaCrO4 Nanorod Films under Confinement and Shear
Authors: Gourdon D. , Yasa M. , Godfrey Alig A. R. , Li Y. , Safinya C. R. , Israelachvili J. N. 
Published: March 2004

AbstractUsing an X‐ray surface forces apparatus (X‐SFA) we have investigated the effects of normal load (stress) and shear on the ordering and tribological properties of 10 nm × 30 nm surfactant‐coated BaCrO4 nanorods in isooctane, confined within submicrometer films. The film structure and corresponding friction forces were monitored as a function of time and shearing distance at different gap sizes and loads. The X‐ray diffraction patterns indicate a cubic phase of nanorods coexisting with a surfactant phase that depends on the load, film thickness, shear rate, and shearing time. Atomic force microscopy and birefringence measurements performed on each surface after a shearing experiment showed ordered domains of nanorods over length scales of several tens of micrometers.
Step‐by‐Step Construction of the Electronic Structure of Molecular Conductors: Conceptual Aspects and Applications
Authors: Rousseau R. , Gener M. , Canadell E. 
Published: March 2004

AbstractA qualitative scheme that leads to the step‐by‐step construction of the band structure and Fermi surface of molecular conductors is developed based on a simple analytical treatment as well as some fundamental symmetry and overlap ideas and the concept of folding. This treatment is valuable in that it provides a detailed understanding of how the crystal and electronic structures of molecular conductors are related. Specifically, the proposed perspective clarifies how relatively weak structural changes can result in significant differences in the transport properties of these materials. Molecular conductors with donor layers of the β″‐type are used in order to illustrate the approach.
Investigation of susceptibility loci identified in the UK rheumatoid arthritis whole‐genome scan in a further series of 217 UK affected sibling pairs
Authors: Eyre Stephen , Barton Anne , Shephard Neil , Hinks Anne , Brintnell William , MacKay Kirsten , Silman Alan , Ollier William , Wordsworth Paul , John Sally , Worthington Jane 
Published: March 2004

AbstractObjectiveA previous whole‐genome scan (WGS) of 182 UK rheumatoid arthritis (RA) affected sibling pair (ASP) families suggested linkage to HLA and 11 other chromosome regions. Replication of such findings in an independent cohort can help to distinguish true linkages from false‐positive linkages. Since RA is a heterogeneous disease, some loci may be linked only in subsets of patients. Thus, the aim of this study was to investigate in an additional set of RA ASP families linkage to regions showing deviation in expected allele‐sharing ratios in the UK WGS and to perform subset analysis on the combined cohort.MethodsTwenty loci were investigated for linkage in 217 Caucasian UK RA ASPs. Stratification analysis was performed on the combined cohort of 377 RA ASP families to account for sex, RA severity, and the shared epitope (SE).ResultsNone of the regions of linkage identified in the initial WGS achieved statistical significance in the second cohort. In contrast, after stratification analysis, 14 regions showed nominal evidence of linkage (logarithm of odds score >0.8) in one or more subgroups. In particular, the strength of evidence for linkage to chromosome 16p was increased in subsets of ASPs with younger age at disease onset (LOD score 2.38) and for linkage to chromosome 6q in female–female ASPs (LOD score 2.31) and in ASPs in which both siblings had 2 copies of the SE (LOD score 3.03).ConclusionThese results support the evidence for heterogeneity of RA. This information will inform the future design of association‐based investigations as the search for disease genes in the linked regions begins.
Association of a programmed death 1 gene polymorphism with the development of rheumatoid arthritis, but not systemic lupus erythematosus
Authors: Lin Shih‐Chang , Yen Jeng‐Hsien , Tsai Jaw‐Ji , Tsai Wen‐Chen , Ou Tsan‐Teng , Liu Hong‐Wen , Chen Chung‐Jen 
Published: March 2004

AbstractObjective.The expression of autoimmunity in mice deficient in programmed death 1 (PD‐1) suggests that PD‐1 is a candidate gene involved in the development of human autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). We therefore tested the potential association between PD‐1 and the development of SLE and RA by conducting case–control genetic‐association studies.Methods.Ninety‐eight SLE patients, 84 RA patients, and sex‐matched control subjects for each disease group were recruited and genotyped for a single‐nucleotide polymorphism, C+872T, in the human PD‐1 gene. The significance of the association of the PD‐1 gene with SLE or with RA was analyzed by statistical tests for the difference in genotype distribution between disease and control groups.Results.The human PD‐1 gene was found to be significantly associated with disease development in RA patients, but not SLE patients. The risk of RA development appeared to be significantly increased by carriage of the T allele (odds ratio 3.32, P < 0.0001) or the C/T genotype (odds ratio 3.52, P < 0.00005).Conclusion.The PD‐1 gene is significantly associated with RA susceptibility, suggesting the possibility that PD‐1 may contribute to the pathogenesis of RA.
Additional genetic susceptibility for rheumatoid arthritis telomeric of the DRB1 locus
Authors: Kilding Rachael , Iles Mark M. , Timms Janine M. , Worthington Jane , Wilson Anthony G. 
Published: March 2004

AbstractObjectiveRheumatoid arthritis (RA) has an estimated genetic contribution of 30–50%, approximately one‐third of which arises from the major histocompatibility complex on 6p21.3. Many studies have implicated alleles of DRB1 that encode a shared epitope. However, several recent studies have suggested that additional telomeric genetic influences may exist. In this study, we sought to investigate whether a separate non‐DRB1 effect could be detected and to determine its likely location.MethodsWe typed 13 single‐nucleotide polymorphisms, located mainly in the telomeric class III region of the major histocompatibility complex, in 164 British Caucasian families with RA that had at least 1 affected offspring and used unconditioned and DRB1‐conditioned transmission disequilibrium tests (TDTs).ResultsUnconditioned TDTs revealed overtransmission of shared epitope alleles (P = 2.12 × 10−5) and an allele of the HLA–B–associated transcript 1 (BAT1) gene in the telomeric class III region (P = 0.009). Using a DRB1‐conditioned TDT to assess whether an independent effect existed, we detected unequal transmission of alleles of lymphocyte‐specific transcript 1 (P = 0.004), BAT1 (P = 0.003), and PG8 (P = 0.003).ConclusionAt least 1 additional non‐DRB1 susceptibility locus for RA exists in an interval that encompasses the junction of the class III and I regions. This is a genomic segment of high linkage disequilibrium containing a large number of poorly characterized immunomodulatory genes.