bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solventless Acid‐Free Synthesis of Mesostructured Titania: Nanovessels for Metal Complexes and Metal Nanoclusters
Authors: Dag Ö. , Soten I. , Çelik Ö. , Polarz S. , Coombs N. , Ozin G.A. 
Published: February 2003

AbstractA new and highly reproducible method to obtain mesostructured titania materials is introduced in this contribution. The mesostructured titania is obtained by employing self‐assembled structures of non‐ionic alkyl‐poly(ethylene oxide) surfactants as templates. The materials are produced without additional solvents such as alcohols, or even water. Only the titanium(IV) ethoxide and the surfactant (C12EO10) are needed. Water, in the form of that attached to the surfactant and from the atmosphere, induces growth of titania nanoclusters in the synthesis sol. It is indicated that these nanoclusters interact with the surfactant EO‐head groups to form a new titanotropic amphiphile. The new amphiphiles self‐assemble into titanium nanocluster–surfactant hybrid lyotropic phases, which are transformed to the final mesostructured materials by further condensation of the titania network. The titania materials can be obtained also with noble‐metal particles immobilized in the mesostructured framework. It is seen that when different metal salts are used as the metal precursors, different interactions with the titania walls are found. The materials are characterized by X‐ray diffraction (XRD), polarization optical microscopy (POM), transmission electron microscopy (TEM), UV‐vis spectroscopy, and micro‐Raman analysis.
Nanocrystalline Transition‐Metal Oxide Spheres with Controlled Multi‐Scale Porosity
Authors: Grosso D. , de A.A. Soler‐Illia G.J. , Crepaldi E.L. , Charleux B. , Sanchez C. 
Published: February 2003

AbstractThis article presents original multi‐scale porous nanocrystalline transition‐metal oxide materials (MO2, where M = Ti, Zr, Ce) that have many potential applications. They were prepared through a one step method that combines sol–gel chemistry, multi‐scale templating approaches, aerosol processing, and specific treatments. The final material presents itself as spheres of controlled diameter, made of a periodically organized mesoporous crystalline network that surrounds spherical macropores, in which each single porosity can be easily and independently adjusted. In addition, a porosity gradient can be generated. The strategy highlighted here can be easily applied to many hierarchically structured sol–gel derived materials. Moreover, this process can easily be scaled up, which could lead to a breakthrough in the industrial production of innovative multiscale porosity materials.
Clinical and genetic aspects of trigonocephaly: A study of 25 cases
Authors: Azimi Cyrus , Kennedy Shelley J. , Chitayat David , Chakraborty Pranesh , Clarke Joe T.R. , Forrest Christopher , Teebi Ahmad S. 
Published: February 2003

AbstractWe reviewed 25 patients ascertained through the finding of trigonocephaly/metopic synostosis as a prominent manifestation. In 16 patients, trigonocephaly/metopic synostosis was the only significant finding (64%); 2 patients had metopic/sagittal synostosis (8%) and in 7 patients the trigonocephaly was part of a syndrome (28%). Among the nonsyndromic cases, 12 were males and 6 were females and the sex ratio was 2 M:1 F. Only one patient with isolated trigonocephaly had an affected parent (5.6%). All nonsyndromic patients had normal psychomotor development. In 2 patients with isolated metopic/sagittal synostosis, FGFR2 and FGFR3 mutations were studied and none were detected. Among the syndromic cases, two had Jacobsen syndrome associated with deletion of chromosome 11q 23 (28.5%). Of the remaining five syndromic cases, different conditions were found including Say‐Meyer syndrome, multiple congenital anomalies and bilateral retinoblastoma with no detectable deletion in chromosome 13q14.2 by G‐banding chromosomal analysis and FISH, I‐cell disease, a new acrocraniofacial dysostosis syndrome, and Opitz C trigonocephaly syndrome. The last two patients were studied for cryptic chromosomal rearrangements, with SKY and subtelomeric FISH probes. Also FGFR2 and FGFR3 mutations were studied in two syndromic cases, but none were found. This study demonstrates that the majority of cases with nonsyndromic trigonocephaly are sporadic and benign, apart from the associated cosmetic implications. Syndromic trigonocephaly cases are causally heterogeneous and associated with chromosomal as well as single gene disorders. An investigation to delineate the underlying cause of trigonocephaly is indicated because of its important implications on medical management for the patient and the reproductive plans for the family. © 2003 Wiley‐Liss, Inc.
Sperm segregation patterns by fluorescence in situ hybridization studies of a 46,XY,t(2;6) heterozygote giving rise to a rare triploid product of conception with a 69,XXY,t(2;6)(p12;q24)der(6)t(2;6)(p12;q24)pat karyotype
Authors: Lim A.S.T. , Lim T.H. , Kee S.K. , Chieng R. , Tay S.K. 
Published: February 2003

AbstractA blighted ovum diagnosed initially by ultrasound was determined to be a partial hydatidiform mole with a 69,XXY,t(2;6)(p12;q24)der(6)t(2;6)(p12;q24)pat karyotype by cytogenetic analysis. The triploid state arose through dispermy in which both spermatozoa carried rearranged chromosomes, one carrying a balanced translocation through alternate segregation and the other an unbalanced derivative chromosome 6 through adjacent 1 segregation. Segregation analysis of 7,000 spermatozoa from the father was performed with a three‐color fluorescence in situ hybridization (FISH) protocol using α‐satellite 6, telomeric 2p, and telomeric 6q probes. Segregation frequencies of normal and balanced products (alternate segregation), adjacent 1, adjacent 2, and 3:1 were 49.9%, 42.4%, 2.5%, and 4.2%, respectively. The high percentage of alternate segregation is consistent with the knowledge of their preferential outcome. However, the high incidence of adjacent 1 sperm highlights the abnormality risk. Alternate and adjacent 1 segregations (92.3%) accounted for the observed rearranged chromosomes in the triploid. The most viable imbalanced combination would be the one carrying the der(6) chromosome, but since the unbalanced segment comprises 3.6% of the haploid autosomal length (HAL), no risk of a viable imbalanced offspring is indicated. However, an increased likelihood of recurrent miscarriages is likely, and this is confirmed by the couple's two earlier miscarriages. Sperm segregation patterns of translocation carriers determined by FISH can help in ascertaining expected and unexpected karyotypes. The high frequency of adjacent 1 products shows that the presence of the additional derivative chromosome in the partial mole, though rare in occurrence, should be less surprising. © 2002 Wiley‐Liss, Inc.
100 Jahre Didehydroaromaten
Authors: Wenk Hans Henning , Winkler Michael , Sander Wolfram 
Published: February 2003

AbstractSeit nunmehr 100 Jahren stehen Didehydroaromaten, die sich formal durch Entfernen zweier Wasserstoffatome von einem aromatischen Ring ableiten, im Blickfeld der Organischen Chemie. Während ortho‐Didehydrobenzol als reaktive Zwischenstufe der nucleophilen aromatischen Substitution in jedem einführenden Lehrbuch über Reaktionsmechanismen Erwähnung findet, galten die meta‐ und para‐Isomere bis vor relativ kurzer Zeit als ausgesprochene Exoten. Diese Situation hat sich durch die Entdeckung der Endiin‐Cytostatika, einer vielversprechenden Klasse von Antitumor‐Wirkstoffen, schlagartig geändert und das Interesse vieler Arbeitsgruppen weltweit wachgerufen. Didehydroaromaten und damit im Zusammenhang stehende Systeme zählen heute zu den am intensivsten untersuchten Verbindungen überhaupt. Dennoch sind viele Aspekte der Chemie dieser reaktiven Intermediate nach wie vor unverstanden. In diesem Aufsatz skizzieren wir die historische Entwicklung und stellen aktuelle Tendenzen heraus.
Sensory Principles of Higher Plants
Authors: Weiler Elmar W. 
Published: February 2003

AbstractPlants respond to a broad variety of stimuli from the interior of their body and from the outside environment. A revolution in our knowledge of the sensory capabilities of plants took place during the last decade, thanks to the consequent application of the tools of molecular genetics and the focusing of most work, in a world‐wide effort, on a single, representative, higher plant: Arabidopsis thaliana. This review concentrates on the complete sensory periphery of higher plants, with focus placed on the principles rather than the details, and such systems that have been functionally identified unambiguously. Higher plants are no less fascinating, no less complex, and no less sensitive than animals, even man, with respect to their sensory capabilities. Plants constantly monitor their environment and their interior situation by using a stunning array of sensory systems, that are mostly different from those of animals or man.
Modeling O2 transport within engineered hepatic devices
Authors: McClelland Randall E. , MacDonald Jeffrey M. , Coger Robin N. 
Published: February 2003

AbstractPredicting and improving oxygen transport within bioartificial liver (BAL) devices continues to be an important engineering challenge since oxygen is one of the critical nutrients necessary for maintaining hepatocyte viability and function. Such a computational model would not only help predict outcomes but it would also allow system modifications to be analyzed prior to developing experimental protocols. This would help to facilitate future design improvements while reducing both experimental time and capital resource costs, and is the focus of the current study. Specifically, a computational model of O2 transport through collagen and microporous collagen ECMs is analyzed for hollow fiber (HF), flat plate (FP), and spheroid BAL designs. By modifying the O2 boundary conditions, hepatocyte O2 consumption levels, O2 permeability of the ECM, and ECM void fractions, O2 transport predictions are determined for each system as a function of time and distance. Accuracy of the predictive model is confirmed by comparing computational vs. experimental results for the HF BAL system. The model's results indicate that O2 transport within all three BAL designs can be improved significantly by incorporating the enhancement technique. This technique modifies a diffusion‐dominant gel ECM into a porous matrix with diffusive and convective flows that mutually transport O2 through the ECMs. Although tortuous pathways increase the porous ECM's overall effective length of O2 travel, the decreased transport resistances of these pathways allow O2 to permeate more effectively into the ECMs. Furthermore, because the HF design employs convective flow on both its inner and outer ECM surfaces, greater control of O2 transport through its ECM is predicted, as compared with the single O2 source inputs of the flat plate and spheroid systems. The importance of this control is evaluated by showing how modifying the O2 concentration and/or transfer coefficients of the convective flows can affect O2 transport. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 12–27, 2003.
A new VFA sensor technique for anaerobic reactor systems
Authors: Pind Peter F. , Angelidaki Irini , Ahring Birgitte K. 
Published: February 2003

AbstractA key parameter for understanding and controling the anaerobic biogas process is the concentration of volatile fatty acids (VFA). However, this information has so far been limited to off‐line measurements using labor‐intensive methods. We have developed a new technique that has made it possible to monitor VFA on‐line in one of the most difficult media: animal slurry or manure. A novel in situ filtration technique has made it possible to perform microfiltration inside a reactor system. This filter enables sampling from closed reactor systems without large‐scale pumping and filters. Furthermore, due to its small size it can be placed in lab‐scale reactors without disturbing the process. Using this filtration technique together with commercially available membrane filters we have constructed a VFA sensor system that can perform automatic analysis of animal slurry at a frequency as high as every 15 minutes. Reproducibility and recovery factors of the entire system have been determined. The VFA sensor has been tested for a period of more than 60 days with more than 1000 samples on both a full‐scale biogas plant and lab‐scale reactors. The measuring range covers specific measurements of acetate, propionate, iso‐/n‐butyrate and iso‐/n‐valerate ranging from 0.1 to 50 mM (6–3000 mg). The measuring range could readily be expanded to more components and both lower and higher concentrations if desired. In addition to the new VFA sensor system, test results from development and testing of the in situ filtration technique are being presented is this article. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 54–61, 2003.
Inhibition of an activated Ras protein with genetically selected peptide aptamers
Authors: Kurtz Stephen E. , Esposito Kim , Tang Weimin , Menzel Rolf 
Published: February 2003

AbstractMutant alleles of Ras maintain an activated, GTP‐bound conformation and relay mitogenic signals that cannot be turned off. A genetic selection in Saccharomyces cerevisiae was used to identify peptide aptamers that suppress the growth arrest phenotype of an activated Ras allele. Peptide aptamers were expressed as C‐terminal fusions to glutathione‐S‐transferase. Modifications that alter the coding capacity of the peptide aptamer indicate it is necessary for Ras2‐Val19 suppression. Aptamer expression also reduces the elevated levels of cAMP and suppresses the heat shock sensitivity characteristic of Ras‐activated yeast cells. The peptide aptamer retains suppressor activity when fused to thioredoxin. The peptide aptamer expression strategy described here indicates that aptamers presented as unconstrained peptides have functional capacity in vivo. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 38–46, 2003.
Interpartical Breakage on Fine Hard Materials by Single and Multiple Compression
Authors: Reichardt Y. , Schönert K. 
Published: February 2003

AbstractThe interparticle breakage of fine feed fractions of quartz, zircon silicate, smelted corundum and silicon carbide is investigated by stressing a particle bed either once with a pressure between 600 and 1800 MPa or several times with a pressure of 100 to 700 MPa. The multiple compression is performed in a press unit with two piston pairs orientated perpendicularly to each other and acting alternatively. Each successive stressing, therefore, disaggregates the compacted bed of the preceding compression. The size‐reduction depends only on the specific energy absorption and not on the pressure level, at which the energy is introduced. The data allows an estimate of the specific comminution energy without any machinery losses for producing a product with a wanted fineness characterized by the maximum particle size to be obtained. These results are much less than the energy consumption of stirred ball mills.
Templateless Assembly of Molecularly Aligned Conductive Polymer Nanowires: A New Approach for Oriented Nanostructures
Authors: Liu Jun , Lin Yuehe , Liang Liang , Voigt James A. , Huber Dale L. , Tian Zhengrong R. , Coker Eric , Mckenzie Bonnie , Mcdermott Matthew J. 
Published: February 2003

AbstractAlthough oriented carbon nanotubes, oriented nanowires of metals, semiconductors and oxides have attracted wide attention, there have been few reports on oriented polymer nanostructures such as nanowires. In this paper we report the assembly of large arrays of oriented nanowires containing molecularly aligned conducting polymers (polyaniline) without using a porous membrane template to support the polymer. The uniform oriented nanowires were prepared through controlled nucleation and growth during a stepwise electrochemical deposition process in which a large number of nuclei were first deposited on the substrate using a large current density. After the initial nucleation, the current density was reduced stepwise in order to grow the oriented nanowires from the nucleation sites created in the first step. The usefulness of these new polymer structures is demonstrated with a chemical sensor device for H2O2, the detection of which is widely investigated for biosensors. Finally, we demonstrated that controlled nucleation and growth is a general approach and has potential for growing oriented nanostructures of other materials.
Polymorphism of 1,2‐Bis(2‐methyl‐5‐p‐methoxyphenyl‐3‐thienyl)perfluorocyclopentene and Photochromic Reactivity of the Single Crystals
Authors: Morimoto Masakazu , Kobatake Seiya , Irie Masahiro 
Published: February 2003

AbstractFour polymorphic crystals were obtained by recrystallization of 1,2‐bis(2‐methyl‐5‐p‐methoxyphenyl‐3‐thienyl)perfluorocyclopentene (1 a) from hexane. All crystals underwent photochromic reactions upon alternate irradiation with ultraviolet (λ=370 nm) and visible light (λ>500 nm). The photocyclization quantum yields were found to be close to unity irrespective of the crystal types, while the photocycloreversion quantum yields were different as much as four times depending on the conformation of the closed‐ring isomers in the crystals.
Redox‐Induced Coordination Isomerization of a Phosphoniobenzophospholide
Authors: Gudat Dietrich , Lewall Burhanshah , Nieger Martin , Detmer Ilka , Szarvas László , Saarenketo Pauli , Marconi Guido 
Published: February 2003

Abstract 1‐Triphenylphosphoniobenzo[c]phospholide 1 reacts with [M(CO)5Br] (M = Mn, Re) and [Mn(CO)3(naphthalene)][BF4] to give complexes cis‐[M(CO)4(1)Br] (5 a,b) and [Mn(CO)3(1)][BF4] (6 a[BF4]), respectively, featuring η1(P)‐ and η5(π)‐coordination of the phosphole ring. The corresponding reactions with [M2(CO)10] proceed with conservation of the metal–metal bond and yield, depending on the reaction temperature, dinuclear complexes [M2(CO)8(1)] (M=Mn, 7 a) or [M2(CO)6(1)2] (M=Mn, Re, 8 a,b) with μ2‐bridging η1(P):η2(PC) coordination of the phosphole moiety. All complexes formed were characterized by spectroscopic data; 5 b, 6 a[BF4], and 8 a,b were characterized by X‐ray diffraction studies as well. The structural and 31P NMR data of the dinuclear manganese complex 8 a suggest that the interaction between the metal atoms and the η2‐bound PC double bond moieties is dominated by the L→M charge‐transfer contribution; this hints at a very low back‐donation ability of the central M2(CO)6 fragment. Investigation of the reactions of the Mn complexes 6 a and 8 a with Mg or ferrocenium hexafluorophosphate ([Fc][PF6]), respectively, revealed that the chemically reversible mutual interconversion between both species was feasible. Likewise, oxidation of the rhenium complex 8 b with [Fc][PF6] gave spectroscopic evidence for the formation of a Re analogue of 6 a. Electrochemical studies suggested that the oxidation 8 a→2 6 a involves two consecutive single‐electron‐transfer steps, the first of which is electrochemically reversible and produces a metastable radical cation that is detectable by ESR spectroscopy. The mutual interconversion between 6 a and 8 a represents the first case of a reversible coordination isomerization of a phosphaarene that is triggered by a redox process and might stimulate further studies directed at the use of dinuclear phosphaarene complexes in redox‐catalysis.
Prevalence of the Alkyl/Phenyl‐Folded Conformation in Benzylic Compounds C6H5CH2‐X‐R (X=O, CH2, CO, S, SO, SO2): Significance of the CH/π Interaction as Evidenced by High‐Level Ab Initio MO Calculations
Authors: Takahashi Osamu , Kohno Yuji , Saito Ko , Nishio Motohiro 
Published: February 2003

AbstractAb initio MO calculations were carried out to examine the conformational energies of various benzylic compounds C6H5CH2XR (X=O, CH2, CO, S, SO, SO2; R=CH3, C2H5, iC3H7, tC4H9) at the MP2/6‐311G(d,p)//MP2/6‐31G(d) level. Rotamers with R/Ph in gauche relationship are generally more stable than the R/Ph anti rotamers. In these stable geometries, the interatomic distance in the interaction of α‐ or β‐CH in the alkyl group and the ipso‐carbon atom of the phenyl ring is short. The computational results are consistent with experimental data from supersonic molecular jet spectroscopy on 3‐n‐propyltoluene and NMR and crystallographic data on structurally related ketones, sulfoxides, and sulfones. In view of this, the alkyl/phenyl‐congested conformation of these compounds has been suggested to be a general phenomenon, rather than an exception. The attractive CH/π interaction has been suggested to be a dominant factor in determining the conformation of simple aralkyl compounds.
Recent trends and racial/ethnic differences in the incidence and treatment of ductal carcinoma in situ of the breast in California women
Authors: Innos Kaire , Horn‐Ross Pamela L. 
Published: February 2003

AbstractBACKGROUNDThe rapid increase in the incidence of ductal carcinoma in situ (DCIS) of the breast in the U.S. has been associated with the widespread adoption of screening mammography. Little is known regarding the incidence and treatment of DCIS in women of racial/ethnic groups other than white and black. The current investigation examined recent trends and racial/ethnic differences in the incidence and treatment of DCIS in California.METHODSAll cases of DCIS diagnosed in women age ≥ 40 years in California between 1988–1999 were included. Age‐adjusted incidence rates for white, black, Hispanic, and Asian‐Pacific Islander women were calculated using the 2000 U.S. female population as the standard. The estimated annual percent change (EAPC) in the rates was calculated using least squares regression.RESULTSThe average annual age‐adjusted incidence of DCIS (1988–1999) was 45.3 per 100,000 in white women, 35.0 in black women, 30.9 in Asian‐Pacific Islander women, and 21.8 in Hispanic women. Although a steady increase in the incidence of DCIS was noted in all racial/ethnic groups over the study period, Asian‐Pacific Islander women were found to have experienced the steepest increase (EAPC = 9.1%), particularly in the age group 50–64 years (EAPC = 12.0%). The DCIS incidence was reported to increase with age in white, black, and Hispanic women, but remained fairly constant after the age of 50 years in Asian‐Pacific Islanders. The proportion of women with DCIS treated with mastectomy decreased from 53% in 1988 to 32% in 1999. Younger women and Asian‐Pacific Islander women reportedly were more likely to undergo mastectomy.CONCLUSIONSConsiderable differences by race/ethnicity and age were observed in DCIS incidence and the change in the incidence in California between 1988 and 1999. Further information is needed to determine whether these differences are because of differential utilization of screening mammography or biologic characteristics of DCIS lesions. Cancer 2003;97:1099–106. © 2003 American Cancer Society.DOI 10.1002/cncr.11104