bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlates of Relative Lethality and Suicidal Intent among Deliberate Self‐Harm Patients
Authors: Haw Camilla , Hawton Keith , Houston Kelly , Townsend Ellen
Published: January 2004

Conflicting findings have been reported regarding the relationship between the potential lethality of acts of deliberate self‐harm (DSH) and suicidal intent, and how each relates to patient characteristics. This study examines the relationship of suicidal intent of DSH to lethality, the relationship of both to patient characteristics, and determines if intent or lethality are risk factors for repetition of DSH. Potential lethality and Suicide Intent Scale (SIS) scores for DSH episodes were examined in a representative sample of 150 patients presenting to a general hospital. Follow‐up interviews were completed 12 to 20 months later. Lethality was strongly associated with high intent. Both lethality and intent were associated with male gender. Suicidal intent but not lethality was associated with the presence of psychiatric disorder and depression. Intent was significantly correlated with hopelessness scale score. Although intent was correlated with both depression and self‐esteem scale scores, these correlations became nonsignificant when the effect of hopelessness was removed. Repetition of DSH during the follow‐up period was related to neither lethality nor intent scores for the original episodes. Lethality and suicidal intent, although related, have somewhat different correlates. Both should be considered when assessing DSH patients, but their relationship to further suicidal behavior does not appear to be straightforward.
Toward an Empirical Taxonomy of Suicide Ideation: A Cluster Analysis of the Youth Risk Behavior Survey
Authors: Flannery William Peter , Sneed Carl D. , Marsh Penny
Published: January 2004

In this study we examined adolescent risk behaviors, giving special attention to suicide ideation. Cluster analysis was used to classify adolescents (N = 2,730) on the Youth Risk Behavior Survey. Six clusters of adolescent risk behavior were identified. Although each risk cluster was distinct, some clusters shared overlapping risk behaviors. Suicide ideation was central to two clusters: the Silent Suicide cluster and the Multiple Risk cluster. The findings demonstrate that suicide ideation is both a unique risk behavior for some adolescents and part of a generalized risk syndrome for other adolescents. A multiple subgroup framework is recommended for understanding adolescent risk behaviors.
Discriminators of Suicide Thoughts and Attempts among Homeless Veterans Who Abuse Substances
Authors: Benda Brent B.
Published: January 2004

Six hundred homeless military veterans who abused substances were examined to determine what factors discriminate between nonsuicidal veterans, those who had suicidal thoughts, and persons who had attempted suicide. Several factors were considered based on attachment theory, including caregiver attachment, sexual abuse, physical abuse, resilience, self‐efficacy, and self‐esteem. Suicide attempters were discriminated from others by psychiatric comorbidity, early abuse, severity of substance abuse, and longevity of drug use. In contrast, the discriminators between nonsuicidal homeless substance abusers and others were elements of attachment and commitments such as marriage, employment, and religiosity. Some implications of the findings for intervention are discussed.
African American and Caucasian Attempters Compared for Suicide Risk Factors: A Preliminary Study
Authors: Roy Alec
Published: January 2004

The aim of the study was to compare African American and Caucasian substance dependent suicide attempters for risk factors for suicidal behavior. One hundred and fifty‐eight African American and 95 Caucasian substance dependent patients who had attempted suicide were interviewed and their family history of suicidal behavior recorded. Patients completed the Childhood Trauma Questionnaire, the Eysenck Personality Questionnaire, and the Foulds Hostility and Direction of Hostility Questionnaire. The results revealed that there were no significant differences between the African American and Caucasian suicide attempters for marital status, age, childhood abuse, or for personality scores for neuroticism, extraversion, psychoticism, or hostility. However, the African American attempters had significantly lower childhood emotional neglect scores. Also, significantly more of the Caucasian attempters had a family history of suicide and current legal problems. Further studies seem warranted examining for differences between African Americans and Caucasians for risk factors for suicidal behavior.
Optical properties of ethyl‐cyanoethyl cellulose/poly(acrylic acid) cholesteric liquid crystalline composite films
Authors: Wang Linge , Wang Xiaohua , Huang Yong
Published: February 2004

Ethyl‐cyanoethyl cellulose [(E–CE)C]/poly(acrylic acid) (PAA) composite films were prepared by photopolymerizing acrylic acid (AA) in (E–CE)C/AA cholesteric liquid crystalline solutions. With the selection of suitable concentrations, (E–CE)C/PAA composite films showed vivid colors due to the selective reflection property of the cholesteric phase. It was found that the wavelength of reflection was a function of the concentration of (E‐CE)C, and the reflectivity was increased with increasing thickness of the film. The selective reflection of the composite holds well upon heating at temperatures below 160°C. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 213–217, 2004
Photopolymerization of an expanding monomer with an aromatic dioxirane
Authors: Smith Robert E. , Pinzino Charles S. , Chappelow Cecil C. , Holder Andrew J. , Kostoryz Elisabet L. , Guthrie Jill R. , Miller Matthew , Yourtee David M. , Eick J. David
Published: February 2004

The objective was to study the photocationic polymerization of an expanding monomer, 1,5,7,11‐tetraoxaspiro[5.5]undecane (TOSU), and an aromatic dioxirane, bisphenol A diglycidyl ether (BADGE). Both homopolymerizations and binary polymerizations were conducted. The homopolymer, poly(TOSU), was found to be a linear poly(carbonate), which was soluble in acetone. Poly(BADGE) products contained ether linkages in addition to primary and secondary alcohol functionalities. Binary polymerization products varied depending on the irradiation time and length of dark cure. 13C‐NMR analysis of binary polymerizate products revealed peaks not seen in homopolymer spectra consistent with the formation of copolymer linkages. Mass spectrometry data revealed peaks consistent with oligomers that contained both TOSU and BADGE mer units. The structures of key reaction products were proposed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 62–71, 2004
Miscibility and properties of blend materials from waterborne polyurethane and carboxymethyl konjac glucomannan
Authors: Yang Guang , Huang Qilin , Zhang Lina , Zhou Jinping , Gao Shanjun
Published: February 2004

We prepared composite materials by blending waterborne polyurethane (WPU) and carboxymethyl konjac glucomannan (CMKGM) with CMKGM content from 15 to 80 wt % in an aqueous system. The structures and properties of the blend materials were characterized by FTIR, dynamic mechanical analysis, ultraviolet spectroscopy, scanning electron microscopy, wide‐angle X‐ray diffraction, thermogravimetric analysis, and tensile testing. The results indicated that the blend sheet with 80 wt % CMKGM exhibited good miscibility and higher tensile strength (89.1 MPa) than that of both WPU (3.2 MPa) and CMKGM (56.4 MPa) sheets. Moreover, with an increase of CMKGM content, the tensile strength, Young's modulus, and thermal stability increased significantly, attributed to intermolecular hydrogen bonding between CMKGM and WPU. Based on the experimental results, the blend materials have good, or a certain degree of, miscibility over the whole range of composition ratio of WPU to CMKGM. In addition, the blend materials exhibited organic solvent resistance. This work not only provided a simple method to prepare environmentally friendly materials, but also expanded the application of CMKGM. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 77–83, 2004
Modifying adhesion of linear low‐density polyethylene to polypropylene by blending with a homogeneous ethylene copolymer
Authors: Poon B. C. , Chum S. P. , Hiltner A. , Baer E.
Published: February 2004

Adhesion of a Ziegler–Natta catalyzed ethylene copolymer (ZNPE) to polypropylene (PP) was studied by measuring the delamination toughness G of coextruded microlayers by using the T‐peel test. Low values of G compared to a homogeneous copolymer with approximately the same short chain branch (SCB) content were attributed to an amorphous interfacial layer of low molecular weight, highly branched ZNPE fractions. Blending ZNPE with a homogeneous metallocene catalyzed copolymer (mPE) increased G. In this regard, mPE with higher SCB content was more effective than mPE with slightly lower SCB content. The ZNPE interface was mimicked by microlayering ZNPE and ZNPE blends with polystyrene from which the ZNPE layers were easily separated without damage to the surface. Examination with atomic force microscopy revealed a soft coating about 8 nm thick on the surface of the ZNPE layer. Blending with mPE reduced or eliminated the amorphous interfacial layer. It was proposed that mPE increased miscibility of low molecular weight, highly branched fractions of ZNPE and prevented their segregation at the interface. After blending with mPE eliminated the interfacial layer, G increased to a value comparable to that of a homogeneous copolymer with about the same SCB content as ZNPE bulk chains. The increase in G was attributed to epitaxial crystallization of the ethylene copolymer in the absence of an amorphous interfacial layer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 109–115, 2004
Formation of thermosensitive water‐soluble copolymers with phosphinic acid groups and the thermosensitivity of the copolymers and copolymer/metal complexes
Authors: Nonaka Takamasa , Hanada Yukiko , Watanabe Tsutomu , Ogata Tomonari , Kurihara Seiji
Published: February 2004

Thermosensitive and water‐soluble copolymers were prepared through the copolymerization of acryloyloxypropyl phosphinic acid (APPA) and N‐isopropyl acrylamide (NIPAAm). The thermosensitivity of the copolymers and copolymer/metal complexes was studied. The APPA–NIPAAm copolymers with less than 11 mol % APPA moiety had a lower critical solution temperature (LCST) of approximately 45°C, but the APPA–NIPAAm copolymers with greater than 21 mol % APPA moiety had no LCST from 25 to 55°C. The APPA–NIPAAm copolymers had a higher adsorption capacity for Sm3+, Nd3+, and La3+ than for Cu2+, Ni2+ and Co2+. The APPA–NIPAAm (10:90) copolymer/metal (Sm3+, Nd3+, or La3+) complexes became water‐insoluble above 45°C at pH 6–7, but the APPA–NIPAAm (10:90) copolymer/metal (Cu2+,Ni2+, or Co2+) complexes were water‐soluble from 25 to 55°C at pH 6–7. The temperature at which both the APPA–NIPAAm copolymers and the copolymer/metal complexes became water‐insoluble increased as the pH values of the solutions increased. The APPA–NIPAAm copolymers were able to separate metal ions from their mixed solutions when the temperature of the solutions was changed; this was followed by centrifugation of the copolymer/metal complexes after the copolymers were added to the metal solutions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 116–125, 2004
Mechanical and fracture behavior of an artificially ultraviolet‐irradiated poly(ethylene‐carbon monoxide) copolymer
Authors: Abanto‐Bueno J. , Lambros J.
Published: February 2004

In this work, 1 wt % carbon monoxide (CO) poly(ethylene‐carbon monoxide) (ECO) copolymer sheets were artificially exposed to ultraviolet (UV) light with a power density of 3 mW/cm2 for up to 130 h. A thorough mechanical characterization of the irradiated material was conducted, in which both the stress–strain data and the values of the quasistatic crack initiation and growth toughness were measured and correlated with companion uniaxial tensile tests and single‐edge‐notched fracture tests. Average values of the elastic modulus, failure strain, and failure stress were determined from the tensile tests. The full‐field optical technique of digital image correlation was used to quantify in‐plane deformation (displacements and displacement gradients) during the fracture experiments and to extract values of the crack initiation and growth fracture toughness. The elastic modulus increased monotonically with UV irradiation for the exposure times used in this investigation. In addition, for low irradiation times of less than 5 h, both the failure strain and failure stress of ECO decreased, and this caused a corresponding decrease in the crack initiation and growth toughness. However, for longer irradiation times, the failure strain remained almost invariable, whereas the failure stress increased by about 25% over that of unirradiated ECO. As a result, for longer irradiation times (>5 h), 1 wt % CO ECO became not only stiffer but also stronger and tougher, as quantified by companion fracture experiments. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 139–148, 2004
Design and synthesis of new photoresist materials for ArF lithography
Authors: Seo Hwang‐Un , Jin Sung‐Ho , Choi Sang‐Jun , Gal Yeong‐Soon , Lim Kwon Taek
Published: February 2004

A new class of photoresist matrix polymers based on vinyl ether–maleic anhydride (VEMA) alternating copolymers was developed for ArF single‐layer lithography. These polymers were synthesized by copolymerization of alkyl vinyl ether and maleic anhydride alternating copolymers with acrylate derivatives containing bulky alicyclic acid‐labile protecting groups. The resulting polymers showed good control of polymerization and high transmittance. Also, these resists exhibited good adhesion to the substrate, high dry‐etching resistance against CF4 mixture gas (1.02 times the etching rate of deep UV resist), and high selectivity to silicon oxide etching. Using an ArF excimer laser exposure system with 0.6 NA, 120‐nm L/S patterns were resolved under conventional illumination. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 165–170, 2004
Fumaryl chloride and maleic anhydride–derived crosslinked functional polymers for nonlinear optical waveguide applications
Authors: Maaref Shahin , Roz Zeina , Sun Sam‐Shajing , Seo Kang , Winston Kizzy , Bonner Carl E.
Published: February 2004

The synthesis, processing, and characterization of new crosslinked functional polymer thin films derived from fumaryl chloride and maleic anhydride is presented. Experimental data demonstrated that this is a versatile, convenient, and cost‐effective method of fabricating ultrastructure crosslinked and functional polymer thin films for potential nonlinear optical (NLO) or other applications where molecular orientation is required. The unsaturated and processable polyester thin films are capable of crosslinking in air to form a hardened lattice under a variety of conditions, including both thermal and photoinitiated crosslinking. The thermal stability of the second harmonic (SHG) signal for a crosslinked NLO thin film was stable at temperatures up to 150°C, which is in contrast to uncrosslinked polymers whose SHG signals typically decreased over 50% below 100°C. Because of the lack of NH/OH groups and their vibrational overtones in the polymer, these crosslinked polyester systems have a great potential for low optical loss applications at 1550 nm communication wavelength. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 317–322, 2004
Engineering the friction‐and‐wear behavior of polyelectrolyte multilayer nanoassemblies through block copolymer surface capping, metallic nanoparticles, and multiwall carbon nanotubes
Authors: Pavoor Prem V. , Gearing Brian P. , Gorga Russell E. , Bellare Anuj , Cohen Robert E.
Published: February 2004

In previous work, it was demonstrated that coating a surface with polyelectrolyte multilayers (PEMs) composed of polyallylamine hydrochloride (PAH) and poly(acrylic acid) (PAA) resulted in increased friction forces at low normal loads. At stress levels sufficient to cause system wear, however, PAH/PAA PEMs provided significant wear protection for the underlying substrate. This report evaluates three strategies for reducing the coefficients of friction associated with PEMs at low normal stress, while retaining their wear‐retarding properties at high normal loads. Anchoring polystyrene‐block‐poly(acrylic acid) to the PAH surface of a multilayer film, less than 10 nm thick, enhanced the hardness, and hence the load‐bearing capacity of these structures. The effect of surface capping was most pronounced at high normal stresses, where substantial wear prevention was observed, accompanied by low friction forces. These films are well suited for systems where wear particle generation hinders smooth operation. The second strategy used the in situ synthesis of silver nanoparticles in the PEM matrix for friction reduction. Optimum levels of silver clusters are required at the surface to reduce the friction forces. Finally, multilayer composites were constructed using PAH and multiwall carbon nanotubes. These assemblies exhibited the lowest values of friction among the strategies studied, at all levels of stress; in addition, substrate wear prevention was also achieved. The tribological behavior of the PEM‐modification strategies was correlated with the mechanical properties of the films, elicited by nanoindentation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 439–448, 2004
On line measurement of crystallinity of nylon 6 nanocomposites by laser Raman spectroscopy and neural networks
Authors: Ergungor Z. , Batur C. , Cakmak M.
Published: February 2004

A neural network is trained to estimate the unknown crystallinity and temperature of Nylon 6 and its nanocomposites while the material is undergoing cooling at a fixed rate. The innovation of the work is that the full spectrum captured by the laser Raman spectroscope is used to train a neural network for estimation of crystallinity and temperature. The small‐angle light scattering (SALS) and differential scanning calorimetry (DSC) data were used to provide the training examples for the neural network. Results indicate that the neural network can provide reliable estimates of the crystallinity and temperature provided that there is a sufficient number of training data available. Neural network methodology is also efficient in establishing the crystallization–temperature relationship as a function of cooling rate and demonstrates the heterogeneous nucleation effect of nanoclay in the nylon 6 matrix. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 474–483, 2004
Weathering studies of epoxidized and hydroxy‐fluoroester pendent guayule rubber in powder coatings
Authors: Gupta Sandhya , Mendon Sharathkumar K. , Thames Shelby F.
Published: February 2004

Although numerous coatings have been synthesized from guayule rubber derivatives, there have been no studies detailing the weatherability of such coatings. We report herein the results of accelerated weathering tests on powder coatings synthesized from epoxidized guayule rubber (EGR) and hydroxy‐fluoroester pendent guayule rubber (FGR) derivatives. Our studies indicate that EGR and FGR powder coatings exposed to alternating cycles of fluorescent UVA light and water condensation for 400 h exhibit reduced yellowing and a high degree of gloss retention. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 493–497, 2004
Vitamin A microencapsulation within poly(methyl methacrylate)‐g‐polyethylenimine microspheres: Localized proton buffering effect on vitamin A stability
Authors: Lee Jong Suk , Nam Yoon Sung , Kang Byung‐Young , Han Sang‐Hoon , Chang Ih‐Seop
Published: February 2004

To stabilize vitamin A in a cosmetic/dermatological formulation, we present here a new encapsulation method based on polymer microspheres having a localized “proton‐buffering” capacity. Poly(methyl methacrylate)‐g‐polyethylenimine (PMMA‐g‐PEI) was prepared by direct condensation grafting of PEI onto poly(methyl methacrylate‐co‐methyl acrylic acid). The reaction was confirmed by FT‐IR analysis showing the amide vibration at 1,550 cm−1. Elemental analysis indicated that the weight content of the grafted PEI was 1.6% (w/w). Vitamin A was encapsulated into PMMA‐g‐PEI microspheres by using an oil‐in‐water (O/W) single emulsion method. The presence of PEI moiety dramatically improved the chemical stability of vitamin A in microspheres. Vitamin A encapsulated within PMMA‐g‐PEI microspheres maintained 91% of its initial activity after 30‐day incubation at 40°C, while only maintaining 60% within plain PMMA microspheres. This study demonstrates that proton‐buffering within hydrophobic polymer matrix is a useful strategy for stabilizing “acid‐labile” active ingredients. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 517–522, 2004
Polypropylene/montmorillonite composites and their application in hybrid fiber preparation by melt‐spinning
Authors: Zhang Xiuqin , Yang Mingshu , Zhao Ying , Zhang Shimin , Dong Xia , Liu Xuexin , Wang Dujin , Xu Duanfu
Published: February 2004

Polypropylene (PP)/organomontmorillonite (OMMT) nanocomposites have been successfully prepared by melt intercalation by using the conventional method of twin‐screw extrusion and subsequently submitted for melt‐spinning. The structure and properties of the PP/clay nanocomposites and hybrid fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), and crystallization dynamics, etc. The organoclay layers were found to disperse in the PP resin at the nanometer level. The nanoscaled OMMT layers, dispersed in the PP matrix, actually played the role of heterogeneous nuclei species in the process of PP crystallization and increased the nucleation speed of the composites, hereby leading to the increase of crystallization rate of the as‐spun fiber. Meanwhile, it was found that the crystallinity of PP/OMMT hybrid fibers is much higher than that of pure PP fiber at the same draw ratios, whereas the orientation of PP/OMMT hybrid fibers is much lower than that of pure PP fiber at the same draw ratios. Because of the effective intercalation of OMMT into PP matrix, the nanocomposites have good spinnability, and the moisture absorption of the final PP fiber is improved. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 552–558, 2004
Kinetic study by FTIR, TMA, and DSC of the curing of a mixture of DGEBA resin and γ‐butyrolactone catalyzed by ytterbium triflate
Authors: Ramis Xavier , Salla Josep Maria , Mas Cristina , Mantecón Ana , Serra Angels
Published: February 2004

A mixture of diglycidylether of bisphenol A (DGEBA) and γ‐butyrolactone (γ‐BL) was cured in the presence of ytterbium triflate as a catalyst. The kinetics of the various elemental processes that occur in the curing process were studied by means of isothermal curing in the FTIR spectrometer. The kinetics of the contraction during the curing was also evaluated by TMA. In both cases, the kinetics was analyzed by means of isoconversional procedure and the kinetic model was determined with the so‐called compensation effect (isokinetic relationship). The isothermal kinetic analysis was compared with that obtained by dynamic curing in DSC. We found that all the reactive processes and the contraction follow a surface‐controlled reaction type of kinetic mechanism, R3. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 381–393, 2004
The role of community college trustees in supporting the foundation
Authors: Nielsen Norm , Newton Wayne , Mitvalsky Cheryle W.
Published: January 2004

The role of the institutional trustees in supporting foundation efforts is explored. Four priorities are described: projecting a positive image for the college, overseeing and maintaining an institutional structure that supports the foundation, sustaining an engaged administration, and encouraging innovation.
Effect of non‐exponential and multi‐exponential decay behavior on the performance of the direct exponential curve resolution algorithm (DECRA) in NMR investigations
Authors: Alam Todd M. , Alam M. Kathleen
Published: January 2004

The effect of non‐exponential and multi‐exponential decay or relaxation behavior on the performance of the direct exponential curve resolution algorithm (DECRA) is investigated through a series of numerical simulations. Three different combinations of decay or relaxation behavior were investigated through DECRA analysis of simulated pulse gradient spin echo (PGSE) NMR diffusion spectra that contained the combination of two individual components. The diffusion decay behavior of one component was described by a single‐exponential decay, while the second component was described by either (1) a multi‐exponential decay, (2) a decay behavior described by the empirical Kohlrausch–Williams–Watts (KWW) relation or (3) a multi‐exponential decay behavior correlated with variations in the NMR spectral line shape. The magnitudes and types of errors produced during the DECRA analysis of spectral data with deviations from a pure single‐exponential decay behavior are presented. It is demonstrated that the deviation from single‐exponential decay impacts the resulting calculated line shapes, the calculated relative concentrations and the quantitative estimation of the decay or relaxation time constants of both components present in the NMR spectra. Copyright © 2004 John Wiley & Sons, Ltd.
Polytopal Rearrangement of [Ni(acac)2(py)]: A New Square Pyramid⇄Trigonal Bipyramid Twist Mechanism
Authors: Daul Claude , Niketic Svetozar , Rauzy Cédrick , Schläpfer Carl‐Wilhelm
Published: February 2004

The interconversion mechanisms between three idealized polytopal forms (a square pyramid and two trigonal bipyramids) of [M(bidentate)2(unidentate)] were investigated by an original combination of molecular mechanics (MM) and density functional theory (DFT) approaches. MM was used to model the mechanistic rearrangement path, and DFT to study selected points along this path. The test case was a five‐coordinate [Ni(acac)2(py)] species. In the case of [Ni(acac)2(py)] it was confirmed (both by MM and by DFT) that the three polytopal forms do indeed represent shallow local minima, of which the square pyramid (SQP) is more stable than the other two. Small energy barriers that separate the three minima prevent spontaneous rearrangement among the polytopal forms in geometry‐optimization simulations. The driving force for MM simulation of the polytopal rearrangements was supplied through the L‐M‐L angle bending terms. MM results for relative energies and geometries are fully supported by DFT. Finally, the implication of the present results to explain some racemization mechanisms of octahedral complexes (namely, the intramolecular bond rupture of tris(chelate) species, and intermolecular dissociation of bis(bidentate) species) is briefly discussed.
Thermodynamic and Kinetic Data for Adduct Formation, cis–trans Isomerization and Redox Reactions of ML4 Complexes: A Case study with Rhodium– and Iridium–tropp Complexes in d8, d9 and d10 Valence Electron Configurations (tropp= Dibenzotropylidene Phosphanes)
Authors: Breher Frank , Rüegger Heinz , Mlakar Marina , Rudolph Manfred , Deblon Stephan , Schönberg Hartmut , Boulmaâz Souad , Thomaier Jörg , Grützmacher Hansjörg
Published: February 2004

The formation of adducts of the square‐planar 16‐electron complexes trans‐[M(troppph)2]+ and cis‐[M(troppph)2]+ (M=Rh, Ir; troppPh=5‐diphenylphosphanyldibenzo[a,d]cycloheptene) with acetonitrile (acn) and Cl−, and the redox chemistry of these complexes was investigated by various physical methods (NMR and UV‐visible spectroscopy, square‐wave voltammetry), in order to obtain some fundamental thermodynamic and kinetic data for these systems. A trans/cis isomerization cannot be detected for [M(troppph)2]+ in non‐coordinating solvents. However, both isomers are connected through equilibria of the type trans‐[M(troppph)2]++L⇄[ ML(troppph)2]n⇄cis‐[M(troppph)2]++L, involving five‐coordinate intermediates [ML(troppph)2]n (L=acn, n=+1; L=Cl−, n=0). Values for Kd (Kf), that is, the dissociation (formation) equilibrium constant, and kd (kf), that is, the dissociation (formation) rate constant, were obtained. The formation reactions are fast, especially with the trans isomers (kf>1×105 m−1 s−1). The reaction with the sterically more hindered cis isomers is at least one order of magnitude slower. The stability of the five‐coordinate complexes [ML(troppph)2]n increases with Ir>Rh and Cl−>acn. The dissociation reaction has a pronounced influence on the square‐wave (SW) voltammograms of trans/cis‐[Ir(troppph)2]+. With the help of the thermodynamic and kinetic data independently determined by other physical means, these reactions could be simulated and allowed the setting up of a reaction sequence. Examination of the data obtained showed that the trans/cis isomerization is a process with a low activation barrier for the four‐coordinate 17‐electron complexes [M(troppph)2]0 and especially that a disproportionation reaction 2 trans/cis‐[M(troppph)2]0→[M(troppph)2]++[M(troppph)2]− may be sufficiently fast to mask the true reactivity of the paramagnetic species, which are probably less reactive than their diamagnetic equilibrium partners.
Theoretical Insights into the Role of a Counterion in Copper‐Catalyzed Enantioselective Cyclopropanation Reactions
Authors: Fraile José M. , García José I. , Gil María J. , Martínez‐Merino Víctor , Mayoral José A. , Salvatella Luis
Published: February 2004

The effect of a coordinating counteranion on the mechanism of CuI‐catalyzed cyclopropanation has been investigated extensively for a medium‐sized reaction model by means of theoretical calculations at the B3LYP/6‐31G(d) level. The main mechanistic features are similar to those found for the cationic (without a counteranion) mechanism, the rate‐limiting step being nitrogen extrusion from a catalyst–diazoester complex to generate a copper–carbene intermediate. The cyclopropanation step takes place through a direct carbene insertion of the metal–carbene species to yield a catalyst–product complex, which can finally regenerate the starting complex. However, the presence of the counteranion has a noticeable influence on the calculated geometries of all the intermediates and transition structures. Furthermore, the existence of a preequilibrium with a dimeric form of the catalyst, together with a higher activation barrier in the insertion step, explains the lower yield of cyclopropane products observed experimentally in the presence of chloride counterion. The stereochemical predictions of a more realistic model (made by considering a chiral bis(oxazoline)–copper(i) catalyst) have been rationalized in terms of the lack of significant steric repulsions, and the model shows good agreement with the low enantioselectivities observed experimentally for these kinds of catalytic systems.
Macrocyclic Glycoclusters: From Amphiphiles through Nanoparticles to Glycoviruses
Authors: Aoyama Yasuhiro
Published: February 2004

Macrocyclic glycocluster amphiphiles are intended to be a covalent‐bundle mimic of clustering glycolipid motifs on the cell membrane. They are irreversibly micellized to give glycocluster nanoparticles (GNPs); their masked hydrophobicity endows them with remarkable saccharide specificities in the interactions with biological saccharide receptors. The GNPs also exhibit unprecedented hydrogen‐bond capacities; they are agglutinated with Na2HPO4 and assembled on plasmid DNA in a number‐, size‐, and shape‐controlled manner to give artificial glycoviral particles capable of transfection. Thus, the intrinsic function of viruses, that is, cell invasion followed by gene expression, is also intrinsic to size‐regulated (∼50 nm) glycoviruses. The growth of glycocluster amphiphiles through nanoparticles to glycoviruses reveals a hierarchical adhesion control of the saccharide clusters.
Synthesis, Fluorescence and Photoisomerization Studies of Azobenzene‐Functionalized Poly(alkyl aryl ether) Dendrimers
Authors: Nithyanandhan Jayaraj , Jayaraman Narayanaswamy , Davis Riju , Das Suresh
Published: February 2004

A series of azobenzene‐functionalized poly(alkyl aryl ether) dendrimers have been synthesized and their photochemical and photophysical properties in solution and as thin films have been investigated. Although the photochemical behavior of the azodendrimers in solution indicated that the azobenzene units behave independently, very similar to the constituent monomer azobenzene unit, the properties of thin solid films of the dendrimers were distinctly different. The azodendrimers, AzoG1, AzoG2, and AzoG3 were observed to form stable supercooled glasses, which showed long‐wavelength absorption and red emission characteristics of J‐aggregates of the azobenzene chromophores. Reversible photoinduced isomerization of the azodendrimers in the glassy state is described.
Synthesis, Characterization and Photochromic Studies of Spirooxazine‐Containing 2,2′‐Bipyridine Ligands and Their Rhenium(i) Tricarbonyl Complexes
Authors: Ko Chi‐Chiu , Wu Li‐Xin , Wong Keith Man‐Chung , Zhu Nianyong , Yam Vivian Wing‐Wah
Published: February 2004

A series of spirooxazine‐containing 2,2′‐bipyridine ligands and their rhenium(i) tricarbonyl complexes has been designed and synthesized, and their photophysical, photochromic and electrochemical properties have been studied. The X‐ray crystal structures of two of the complexes have been determined. Detailed studies showed that the emission properties of the complexes could readily be switched through photochromic reactions.
Aqueous‐Solution Growth of GaP and InP Nanowires: A General Route to Phosphide, Oxide, Sulfide, and Tungstate Nanowires
Authors: Xiong Yujie , Xie Yi , Li Zhengquan , Li Xiaoxu , Gao Shanmin
Published: February 2004

A general synthetic route has been developed for the growth of metal phosphide, oxide, sulfide, and tungstate nanowires in aqueous solution. In detail, cetyltrimethylammonium cations (CTA+) can be combined with anionic inorganic species along a co‐condensation mechanism to form lamellar inorganic–surfactant intercalated mesostructures, which serve as both microreactors and reactants for the growth of nanowires. For example, GaP, InP, γ‐MnO2, ZnO, SnS2, ZnS, CdWO4, and ZnWO4 nanowires have been grown by this route. To the best of our knowledge, this is the first time that the synthesis of GaP and InP nanowires in aqueous solution has been achieved. This strategy is expected to extend to grow nanowires of other materials in solution or by vapor transport routes, since the nanowire growth of any inorganic materials can be realized by selecting an appropriate reaction and its corresponding lamellar inorganic–surfactant precursors.
Cover Picture: Biologically Active Compounds through Catalysis: Efficient Synthesis of N‐(Heteroarylcarbonyl)‐N′‐(arylalkyl)piperazines (Chem. Eur. J. 3/2004)
Authors: Kumar Kamal , Michalik Dirk , Garcia Castro Ivette , Tillack Annegret , Zapf Alexander , Arlt Michael , Heinrich Timo , Böttcher Henning , Beller Matthias
Published: February 2004

The cover picture shows the combination of catalysis with the synthesis of biologically active substances that are active as central nervous system agents. In the background autoclave equipment is shown, which is necessary to perform these reactions. For more details please see the article by M. Beller et al. on p. 746ff.
Transportverhalten und Strukturbildung granularer Materie auf Schwingförderern
Authors: Rouijaa M. , Krülle C. , Rehberg I. , Grochowski R. , Walzel P.
Published: February 2004

No abstracts.
Applikationsuntersuchungen zur Photonenkorrelationsspektroskopie im Rückstreubereich
Authors: Kätzel U. , Stintz M. , Ripperger S.
Published: February 2004

No abstracts.
Destillation viskoser Systeme
Authors: Böcker S. , Ronge G.
Published: February 2004

No abstracts.
Modellierung von Mischung und Reaktion in turbulenten Mehrphasenströmungen mittels Verteilungsfunktionen
Authors: Brandt M. , Gharaibah E. , Polifke W.
Published: February 2004

No abstracts.
Kristallisationsfouling in Bodenkolonnen
Authors: Großerichter D. , Stichlmair J.
Published: February 2004

No abstracts.
A conductivity‐dependent phase transition from closed‐loop to open‐loop dendritic networks
Authors: Smyth David , Hübler Alfred
Published: January 2004

Motivated by a principle of minimum dissipation per channel length, we introduce a model for branching, hierarchical networks in an open, dissipative system. Global properties of the resulting structures are observed to scale with the ratio of conductivity in the dendrite material to conductivity in the lattice material. Beyond a critical conductivity ratio, the resulting structures are naturally self‐avoiding and possess scale‐independent branching ratios. Our findings suggest that the conductivity ratio determines the geometric properties of naturally arising dendritic structures. We discuss empirical verification in the context of a system of self‐organizing agglomerates of metal particles in castor oil. © 2004 Wiley Periodicals, Inc. Complexity 9: 56–60, 2004
Life‐like self‐reproducers
Authors: Bilotta Eleonora , Lafusa Antonio , Pantano Pietro
Published: January 2004

In order to understand the interplay among information, genetic instructions, and phenotypic variations, self‐reproducers discovered in two‐dimensional cellular automata are considered as proto‐organisms, which undergo to mutations as they were in a real environmental situation. We realized a computational model through which we have been able to discover the genetic map of the self‐reproducers and the networks they use. Identifying in these maps sets of different functional genes, we found that mutations in the genetic sequences could affect both external shapes and behavior of the self‐reproducers, thus realizing different life‐like strategies in the evolution process. The results highlight that some strategies evolution uses in selecting organisms that are fitting with changing environmental situations maintain the self‐reproducing function, whereas other variations create new self‐reproducers. These self‐reproducers in turn realize different genetic networks, which can be very different from the basic ancestors pools. The mutations that are disruptive bring self‐reproducers to disappear, while other proto‐organisms are generated. © 2004 Wiley Periodicals, Inc. Complexity 9: 38–55, 2004
Leukocyte attraction through the CCR5 receptor controls progress from insulitis to diabetes in non‐obese diabetic mice
Authors: Carvalho‐Pinto Carla , García María I. , Gómez Lucio , Ballesteros André , Zaballos Angel , Flores Juana M. , Mellado Mario , Rodríguez‐Frade José Miguel , Balomenos Dimitrios , Martínez‐A. Carlos
Published: February 2004

Lymphocyte infiltration to pancreatic islets is associated to chemoattraction, as are other inflammatory autoimmune processes. We examined whether development of insulitis and diabetes dependson chemoattraction of lymphocytes via the CCR5 chemokine receptor. In non‐obese diabetic (NOD) mice, a substantial fraction of peripheral T cells and virtually all B cells expressed high CCR5 levels. CCR5 expression characterized the effector T cell phenotype, suggesting their potential involvement in disease development. In view of these findings and the CCL5 (RANTES, the CCR5 ligand) expression by pancreatic islets, we treated NOD mice with a neutralizing anti‐CCR5 antibody. This did not influence peri‐insulitis advancement, but inhibited β‐cell destruction and diabetes. These data demonstrate a role of CCR5‐dependent chemoattraction in insulitis progression to islet destruction, suggesting the potential value of therapeutic intervention by CCR5 targeting.
Leukemic plasmacytoid dendritic cells share phenotypic and functional features with their normal counterparts
Authors: Chaperot Laurence , Perrot Ivan , Jacob Marie‐Christine , Blanchard Dominique , Salaun Véronique , Deneys Véronique , Lebecque Serge , Brière Francine , Bensa Jean‐Claude , Plumas Joël
Published: February 2004

This work aims to further characterize the newly described leukemic plasmacytoid dendritic cells (LPDC), for which we had previously demonstrated their normal, PDC‐like ability to produce IFN‐α. In addition, LPDC also express the specific antigens BDCA‐2 and BDCA‐4. Importantly, they become fully competent antigen‐presenting cells (APC) after a short maturation induced by IL‐3 + CD40L or virus, exhibiting a characteristic APC phenotype (high expression of CD83 and of the costimulatory molecules CD40, CD80, CD86). Whereas IL‐3 + CD40L‐activated LPDC prime naive CD4+ T cells towards a Th2 pathway (IL‐4‐secreting T cells), virus‐activated LPDC drive a Th1 profile (IFN‐γ–secreting T cells). Moreover, we show in one case that LPDC are able to capture, process and present exogenous antigens, leading to the activation of both CD4+ and CD8+ T cell clones in an antigen‐specific manner. This study further characterizes the phenotype and immunological functions of LPDC.
The anti‐apoptotic factor Bcl‐2 can functionally substitute for the B cell survival but not for the marginal zone B cell differentiation activity of BAFF
Authors: Tardivel Aubry , Tinel Antoine , Lens Susanne , Steiner Quynh‐Giao , Sauberli Estelle , Wilson Anne , Mackay Fabienne , Rolink Antonius G. , Beermann Friedrich , Tschopp Jürg , Schneider Pascal
Published: February 2004

The TNF family ligand B cell‐activating factor (BAFF, BLyS, TALL‐1) is an essential factor for B cell development. BAFF binds to three receptors, BAFF‐R, transmembrane activator and CAML interactor (TACI), and B cell maturation antigen (BCMA), but only BAFF‐R is required for successful survival and maturation of splenic B cells. To test whether the effect of BAFF is due to the up‐regulation of anti‐apoptotic factors, TACI‐Ig‐transgenic mice, in which BAFF function is inhibited, were crossed with transgenic mice expressing FLICE‐inhibitory protein (FLIP) or Bcl‐2 in the B cell compartment. FLIP expression did not rescue B cells, while enforced Bcl‐2 expression restored peripheral B cells and the ability to mount T‐dependent antibody responses. However, many B cells retained immaturity markers and failed to express normal amounts of CD21. Marginal zone B cells were not restored and the T‐independent IgG3, but not IgM, response was impaired in the TACI‐Ig×Bcl‐2 mice. These results suggest that BAFF is required not only to inhibit apoptosis of maturating B cells, but also to promote differentiation events, in particular those leading to the generation of marginal zone B cells.
Microwave‐Assisted Solvent‐Free Synthesis of Hexahydrochromeno[4,3‐b]pyrroles
Authors: Pospíšil Jiří , Potáček Milan
Published: February 2004

We report the microwave‐assisted solvent‐free synthesis of hexahydrochromeno[4,3‐b]pyrroles. Intramolecular 1,3‐dipolar cycloadditions proceed under these conditions within 15 min in 80% yields. Moreover, we have observed pronounced steric requirements of alkyl substituents toward the 1,3‐dipolar cycloadditions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Enantioselective Total Synthesis of a trans‐Hydrindane Rings/Side‐Chain Building‐Block of Vitamin D − Asymmetric Induction in an Acid‐Catalyzed Conjugate‐Addition Reaction
Authors: Gorobets Evgueni , Stepanenko Viatcheslav , Wicha Jerzy
Published: February 2004

For the enantioselective total synthesis of 1α,25‐dihydroxyvitamin D3 (3), we have developed an enantioselective approach to the “northern” portion building‐block 8, starting from the optically active hexanoic acid derivative 44, 2‐methylcyclopent‐2‐en‐1‐one (10) and 1‐(phenylthio)but‐3‐en‐2‐one (9). The steric course of the addition reaction of homochiral (S)‐ketene acetals 28, 40, 44 and 58 with 10 was examined. We found that in the cases of 28, 44 and 40, the reactions occur with high simple and induced (facial) diastereoselectivities. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Carcinogen inducibility in vivo and down‐regulation of DMBT1 during breast carcinogenesis
Authors: Mollenhauer Jan , Helmke Burkhard , Medina Daniel , Bergmann Gaby , Gassler Nikolaus , Müller Hanna , Lyer Stefan , Diedrichs Laura , Renner Marcus , Wittig Rainer , Blaich Stephanie , Hamann Ute , Madsen Jens , Holmskov Uffe , Bikker Floris , Ligtenberg Antoon , Carlén Anette , Olsson Jan , Otto Herwart F. , O'Malley Bert , Poustka Annemarie
Published: January 2004

Deleted in malignant brain tumors 1 (DMBT1) has been proposed as a candidate tumor suppressor for brain and epithelial cancer. Initial studies suggested loss of expression rather than mutation as the predominant mode of DMBT1 inactivation. However, in situ studies in lung cancer demonstrated highly sophisticated changes of DMBT1 expression and localization, pointing to a chronological order of events. Here we report on the investigation of DMBT1 in breast cancer in order to test whether these principles might also be attributable to other tumor types. Comprehensive mutational analyses did not uncover unambiguous inactivating DMBT1 mutations in breast cancer. Expression analyses in the human and mouse mammary glands pointed to the necessity of DMBT1 induction. While age‐dependent and hormonal effects could be ruled out, 9 of 10 mice showed induction of Dmbt1 expression after administration of the carcinogen 7,12‐dimethybenz(α)anthracene prior to the onset of tumorigenesis or other histopathological changes. DMBT1 displayed significant up‐regulation in human tumor–flanking tissues compared to in normal breast tissues (P < 0.05). However, the breast tumor cells displayed a switch from lumenal secretion to secretion to the extracellular matrix and a significant down‐regulation compared to that in matched normal flanking tissues (P < 0.01). We concluded that loss of expression also is the predominant mode of DMBT1 inactivation in breast cancer. The dynamic behavior of DMBT1 in lung carcinoma is fully reflected in breast cancer, which suggests that this behavior might be common to tumor types arising from monolayered epithelia. © 2003 Wiley‐Liss, Inc.
Identification of cytogenetic subgroups and karyotypic pathways of clonal evolution in follicular lymphomas
Authors: Höglund Mattias , Sehn Laurie , Connors Joseph M. , Gascoyne Randy D. , Siebert Reiner , Säll Torbjörn , Mitelman Felix , Horsman Douglas E.
Published: January 2004

Follicular lymphoma (FL) is characterized by the activation ofBCL2through t(14;18)(q32;q21). Additional acquired mutations are necessary to generate a fully malignant clonal proliferation. Many of these secondary genetic alterations are visible in the clonal karyotype; however, the sequence by which they arise and their influence on clinical behavior have not been determined. The ability to address these issues has been hampered by the lack of computational methods to manipulate complex chromosomal data in a sufficiently large cohort of cases. In the present investigation, we analyzed secondary karyotypic alterations in 336 cases of FL with t(14;18) to identify the most common regions of recurrent chromosomal gain or loss. This revealed 29 recurrent changes present in more than 5% of the tumors. Each tumor karyotype was then assessed for the presence or absence of each of these 29 specific changes. By statistical means, we show that the chromosomal changes arise in an apparent temporal order, with distinct early and late changes. We identify, by principal‐components analysis, four possible cytogenetic pathways that characterize the early stages of clonal evolution, which converge to a common route at later stages. We show that FLs with t(14;18) may be classified into cytogenetic subgroups determined by the presence or absence of 6q−, +7, or der(18)t(14;18). Correlation with clinical outcomes in a subset of cases with clinical data revealed del(17p) and +12 to be correlated with an adverse clinical outcome. The clinical implications of these pathways of clonal evolution need to be examined on a prospective basis in a large cohort of FLs. © 2003 Wiley‐Liss, Inc.