bluuebunny/crossref_metadata_2025 huggingface dataset:
Heavy Metal Adsorption by Montmorillonites Modified with Natural Organic Cations
Authors: Cruz-Guzmán M. , Celis R. , Hermosín M. C. , Koskinen W. C. , Nater E. A. , Cornejo J.
Published: January 2006

Agricultural and industrial pollution release large amounts of heavy metals into the atmosphere, surface water, soil, and plants. The protection and restoration of soils and water contaminated with heavy metals generate a great need to develop efficient adsorbents for these pollutants. This study reports the adsorption of Pb(II) and Hg(II) by two reference montmorillonites, Wyoming (SWy‐2) and Arizona (SAz‐1), that were pretreated with various natural organic cations containing different functional groups (L‐carnitine, L‐cysteine ethyl ester, L‐cystine dimethyl ester, and thiamine cations) and with synthetic, nonfunctionalized organic cations (hexadecyltrimethylammonium [HDTMA] and phenyltrimethylammonium [PTMA] cations). Most of the organoclays adsorbed less Pb(II) than the untreated montmorillonites, with the exception of the L‐carnitine–treated montmorillonites. The carboxyl functional group on L‐carnitine was apparently effective for complexing Pb. In contrast, Hg(II) adsorption was greatly increased by several of the organic cation pretreatments. Sulfur‐containing organic functional groups enhanced Hg(II) adsorption. The synthetic organic cations PTMA and HDTMA suppressed adsorption of Pb(II) and Hg(II) because these organic cations competed with the metals for adsorption sites on the clay surfaces and lack organic functional groups capable of interacting with the heavy metals. These findings are consistent with prior understanding of organic functional group‐metal complexation reactions but go further by demonstrating that organoclays can be selectively functionalized with natural organic cations to enhance their affinity for heavy metals.
Corn Stover Impacts on Near‐Surface Soil Properties of No‐Till Corn in Ohio
Authors: Blanco-Canqui Humberto , Lal R. , Post W. M. , Izaurralde R. C. , Owens L. B.
Published: January 2006

Corn (Zea maysL.) stover is a primary biofuel feedstock and its expanded use could help reduce reliance on fossil fuels and net CO2emissions. Excessive stover removal may, however, negatively impact near‐surface soil properties within a short period after removal. We assessed changes in soil crust strength, bulk density (ρb), and water content over a 1‐yr period following a systematic removal or addition of stover from three no‐till soils under corn in Ohio. Soils from ongoing experiments at the North Appalachian Experimental Watershed (NAEW), Western Agricultural Experiment Station (WAES), and Northwestern Agricultural Experiment Station (NWAES) of Ohio Agricultural Research and Development Center (OARDC) were studied. Six stover treatments of 0 (T0), 25 (T25), 50 (T50), 75 (T75), 100 (T100), and 200 (T200)% were imposed on 3 by 3 m plots corresponding to 0, 1.25, 2.50, 3.75, 5.00, and 10.00 Mg ha−1of stover, respectively. Cone index (CI), shear strength (SHEAR), ρb, and volumetric water content (θv) were measured monthly from June through December 2004 and in May 2005. Effects of stover removal on increasing CI and SHEAR were soil‐specific. Stover removal consistently increased ρband decreased θvacross soils (P< 0.01). Compared with the normal stover treatment (T100), doubling the amount of stover (T200) did not significantly affect soil properties except θvwhere, after 1 yr, T200 increased θvby 1.3 to 1.6 times compared with T100 across all sites (P< 0.05). After 1 yr, complete stover removal (T0) increased CI by 1.4 times and SHEAR by 1.3 times at NAEW compared with T100 and T75, but CI increases at other sites were nonsignificant. At NWAES, T0 increased SHEAR by 26% compared with T100 (P< 0.05). The T0 decreased θvby two to four times except in winter months and increased ρbby about 10% compared with T100 (P< 0.05). In a short‐term test, stover removal resulted in increased soil crust strength and reduced soil water content.
Adsorption of Polyacrylamide on Smectite, Illite, and Kaolinite
Authors: Deng Youjun , Dixon Joe B. , White G. Norman
Published: January 2006

Interactions between polyacrylamides (PAMs) and clay minerals are the primary reactions in most applications of the water‐soluble polymers. Our main objectives were to study (i) the effects of charge of PAM on the flocculation/dispersion of clay suspensions and on the adsorption of the polymers on clays, and (ii) the surface properties of PAM‐clay complexes. Three PAMs—an anionic PAM 836A, a nonionic PAM 903N, and a cationic PAM 494C—were used to react with three common clay minerals—smectite, kaolinite, and illite. In the polymer concentration range tested (0–1.2 g L−1), the anionic PAM 836A increased the dispersion of the clay suspensions but the cationic PAM 494C promoted the flocculation. The strong flocculation function of cationic PAM 494C made trapped clay particles inaccessible for adsorption despite its highest affinity for clay surfaces. The adsorption of the polymers was irreversible. Nonionic PAM 903N and cationic PAM 494C intercalated smectite but anionic PAM 836A did not. The adsorbed polymer moderately altered the charge properties: the cation exchange capacity (CEC) and the abilities to remove heavy metal Cu and Cr had the following order: anionic PAM 836A‐clay > nonionic PAM 903N‐clay ≈ clay > cationic PAM 494C‐clay. The PAM‐clay complexes did not show distinct adsorption for hydrophobic chlorophenols, indicating that the adsorbed polymers did not increase the hydrophobicity of the clay surfaces.
Harnessing the Actuation Potential of Solid‐State Intercalation Compounds
Authors: Koyama Y. , Chin T. E. , Rhyner U. , Holman R. K. , Hall S. R. , Chiang Y.‐M.
Published: January 2006

High‐strain, high‐force mechanical actuation technologies are desirable for numerous applications ranging from microelectromechanical systems (MEMS) to large‐scale “smart structures” that are able to change shape to optimize performance. Here we show that electrochemical intercalation of inorganic compounds of high elastic modulus offers a low‐voltage mechanism (less than 5 V) with intrinsic energy density approaching that of hydraulics and more than a hundred times greater than that of existing field‐operated mechanisms, such as piezostriction and magnetostriction. Exploitation of the reversible crystallographic strains (several percent) of intercalation compounds while under high stress is key to realization of the available energy. Using a micromachined actuator design, we test the strain capability of oriented graphite due to electrochemical lithiation under stresses up to 200 MPa. We further demonstrate that simultaneous electrochemical expansion of the LiCoO2/graphite cathode/anode couple can be exploited for actuation under stresses up to ∼ 20 MPa in laminated macroscopic composite actuators of similar design to current lithium‐ion batteries. While the transport‐limited actuation mechanism of these devices results in intrinsically slower actuation compared to most ferroic materials, we demonstrate up to 6.7 mHz (150 s) cyclic actuation in a laminated actuator designed for a high charge/discharge rate. The potential for a new class of high‐strain, high‐force, moderate‐frequency actuators suitable for a broad range of applications is suggested.
Polymer flocculation of calcite: Population balance model
Authors: Heath Alex R. , Bahri Parisa A. , Fawell Phillip D. , Farrow John B.
Published: January 2006

A population balance (PB) model is used to describe the aggregation/breakage kinetics of calcite flocculation in turbulent pipe flow. The model describes simultaneous aggregation and breakage, and accounts for likely process variables: fluid shear, flocculant dosage, primary particle size and solid fraction, using four fitted parameters. Particle collision is described by the turbulent collision kernel of Saffman and Turner,1 however, the capture efficiency (α) is initially set to equal zero until the point of flocculant addition, then increases rapidly as described by an equation accounting for flocculant mixing/adsorption. Particles aggregated by high‐molecular weight polymer flocculant typically do not achieve a steady‐state aggregate size, where the rates of aggregation and breakage are equal. Instead, the aggregate size decreases gradually due to polymer chain scission or rearrangement on repeated aggregation/breakage. This phenomenon is accounted for in the model by a flocculant strength degradation term. © 2006 American Institute of Chemical Engineers AIChE J, 2006
CFD simulation of gas–liquid stirred vessel: VC, S33, and L33 flow regimes
Authors: Khopkar Avinash R. , Ranade Vivek V.
Published: January 2006

A comprehensive computational model based on the Eulerian–Eulerian approach was developed to simulate gas–liquid flows in a stirred vessel. A separate submodel was developed to quantitatively understand the influence of turbulence and presence of neighboring bubbles on drag acting on bubbles. This submodel was used to identify an appropriate correlation for estimating the interphase drag force. The standard k–ϵ turbulence model was used to simulate turbulent gas–liquid flows in a stirred vessel. A computational snapshot approach was used to simulate motion of the standard Rushton turbine in a fully baffled vessel. The computational model was mapped onto FLUENT4.5, a commercial CFD solver. The model predictions were compared with the previously published experimental data of Bombac and co‐workers. The model was used to simulate three distinct flow regimes in gas–liquid stirred vessels: vortex clinging (VC), alternating small cavities (S33), and alternating large cavities (L33). The predicted results show reasonably good agreement with the experimental data for all three regimes. The computational model and results discussed in this work would be useful for understanding and simulating gas holdup distribution and flow regimes in stirred vessels. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Negative perceived paternal parenting is associated with dopamine D2 receptor exon 8 and GABA(A) alpha 6 receptor variants: An explorative study
Authors: Lucht Michael , Barnow Sven , Schroeder Winnie , Grabe Hans Joergen , Finckh Ulrich , John Ulrich , Freyberger Harald J. , Herrmann Falko H.
Published: January 2006

Twin studies suggest a genetic influence upon perceived parenting. The D2 dopaminergic receptor is involved in the modulation of social behaviors, and might influence parenting and its perception. A polymorphism (E8) in exon 8 of the D2 receptor gene (DRD2) has been previously associated with alcoholism‐related phenotypes. Similarly, the Pro385Ser variant of GABRA6, the polymorphic gene for GABA(A) receptor α6 subunit, has been associated with alcohol‐ and depression‐related traits; and rat pups maintained a more immature GABAR phenotype after brief separation distress. The relationships among DRD2 (E8) and GABRA6 (Pro385Ser) polymorphisms, and perceived parenting were studied here. The association of DRD2 (E8) and GABRA6 (Pro385Ser) genotypes and perceived parental rearing behavior (short‐EMBU; questionnaire concerning own memories concerning upbringing) were determined in 207 unrelated adults using multivariate analysis of variance. Temperaments (Temperament and Character Inventory; TCI) were included as covariates. Probands with DRD2 (E8) A/A genotype showed higher scores for father rejection (P = 0.011), parents overprotection (P = 0.021), and father overprotection (P = 0.016) in the total group. An interaction between DRD2 and GABRA6 genotypes on father rejection (P = 0.010) and parents rejection (P = 0.030) was also observed. Further analyses showed that these associations were restricted to the female subgroup only; however, secondary gender‐specific analyses were not corrected for multiple testing. Our findings support a role for DRD2 (E8) and GABRA6 (Pro385Ser) in perceived parenting. © 2006 Wiley‐Liss, Inc.
Mobility in Central European Late Eneolithic and Early Bronze Age: Femoral cross‐sectional geometry
Authors: Sládek Vladimír , Berner Margit , Sailer Robert
Published: January 2006

Some scholars explain the absence of settlements in the Bohemian and Moravian Late Eneolithic (Corded Ware archaeological culture) as a consequence of pastoral subsistence with a high degree of mobility. However, recent archaeological studies argued that the archaeological record of the Late Eneolithic in Central Europe exhibits evidence for sedentary subsistence with mixed agriculture, similar to the subsequent Early Bronze Age. Because the archaeological data do not allow us to address unambiguously the mobility pattern in these periods, we used cross‐sectional analysis of the femoral midshaft to test mobility directly on the human skeletal record. The results of femoral midshaft geometry do not support a high degree of mobility in the Late Eneolithic in Central Europe. This conclusion is supported mainly by no significant differences in male groups between the Late Eneolithic and Early Bronze Age in mechanical robusticity and shape of the femoral midshaft, although Corded Ware males still exhibit the highest absolute mean values of the diaphyseal shape (IA‐P/IM‐L) ratio and antero‐posterior second moment of area. However, Late Eneolithic females have significantly higher torsional and overall bending rigidity because of a significantly higher medio‐lateral second moment of area. This finding cannot be directly linked with a higher degree of long‐distance mobility for these females. A significant difference was also found in overall decrease of size parameters of the femoral midshaft cross section for one of the Early Bronze Age samples, the Wieselburger females. Since the decrease of size and mechanical robusticity for Wieselburger females does not correspond with the parameters of Early Bronze Age females, we can expect a mosaic pattern of changes during the Late Eneolithic and Early Bronze Age period, instead of a simple unidirectional (diachronic) change of the mechanical environment. Am J Phys Anthropol, 2006 © 2006 Wiley‐Liss, Inc.
Dentition of moustached tamarins (Saguinus mystax mystax) from Padre Isla, Peru, part 1: Quantitative variation
Authors: Tornow Matthew A. , Ford Susan M. , Garber Paul A. , de sa Sauerbrunn Edward
Published: January 2006

Analyses of dental variation in geographically restricted, wild populations of primates are extremely rare; however, such data form the best source for models of likely degrees of variation within and between fossil species. Data from dental casts of a geographically restricted population of moustached tamarins (Saguinus mystax mystax) from Padre Isla, Peru, document high levels of dental variability, as measured by coefficients of variation, in a nonsexually dimorphic species, despite its isolation and small population size. Like other primates, moustached tamarins show lower variability in the dimensions of the first molars and increased variability in the dimensions of the final molars in the toothrow. Moustached tamarins from Padre Isla have a distinctive pattern of variability in the remaining teeth, including more stable tooth lengths in the anterior and posterior portions of the toothrow, and more stable tooth widths in the midregion of the toothrow. High variability in incisor width may be due to age effects of a distinctive diet and pattern of dental wear. Am J Phys Anthropol, 2006. © 2006 Wiley‐Liss, Inc.
Periventricular leukomalacia specifically affects cortical MEG response to biological motion
Authors: Pavlova Marina , Marconato Fabio , Sokolov Alexander , Braun Christoph , Birbaumer Niels , Krägeloh‐Mann Ingeborg
Published: January 2006

Objective

Periventricular leukomalacia (PVL) underlies most of the neurological morbidity including visual‐perceptual deficits in survivors of premature birth. However, it is unknown whether and, if so, how PVL affects functional cortical activity.

Methods

Here, we assessed changes in the magnetoencephalographic (MEG) response to visual displays depicting human locomotion in adolescents who were born premature with magnetic resonance imaging signs of PVL.

Results

Dynamics of MEG activity parallel behavioral deficits. Early (140–170 milliseconds) brain activation over the right parietal cortex was weaker in patients compared with term‐born controls.

Interpretation

This is the first evidence for stimulus‐specific modulation of cortical activity by periventricular lesions providing new insights into the functional pathology of PVL. Ann Neurol 2006
A novel hereditary small vessel disease of the brain
Authors: Verreault Steve , Joutel Anne , Riant Florence , Neves Georgina , Rui Silva Mario , Maciazek Jacqueline , Tournier‐Lasserve Elizabeth , Bousser Marie‐Germaine , Chabriat Hugues
Published: January 2006

Objective

Only few hereditary ischemic small vessel diseases of the brain (SVDB) have been reported so far. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most frequent of them. Herein, we report a family affected by a SVDB distinct from CADASIL.

Methods

After the occurrence of a small deep infarct associated with white matter lesions both in a 46‐year‐old man and in his 52‐year‐old sister, clinical and neuroimaging investigations were conducted in 13 of their relatives originating from Portugal. Other investigations included (1) skin biopsy immunostaining with a Notch3 monoclonal antibody, (2) sequencing of the 23 exons encoding the epidermal growth factor–like domains of the NOTCH3 gene, and (3) a NOTCH3 locus haplotype analysis.

Results

Diffuse white matter hyperintensities were observed on T2‐weighted magnetic resonance imaging (MRI) in six individuals. In contrast with MRI results in the father and paternal uncle of the proband who were hypertensive, white matter lesions were extensive in the mother who had no vascular risk factor. MRI data in four asymptomatic family members together with the results in the two initial cases were suggestive of an underlying hereditary small vessel disease of the brain. Skin biopsy and NOTCH3 gene mutation screening were negative. Haplotype analysis excluded the NOTCH3 locus.

Interpretation

These data strongly suggest that this family is affected by a novel hereditary small vessel disease of the brainand that the mutated gene is distinct from NOTCH3. Ann Neurol 2006
Effects of reactive low‐profile additives on the properties of cured unsaturated polyester resins. II. Glass‐transition temperature and mechanical properties
Authors: Dong Jyh‐Ping , Lee Jeng‐Huei , Lai Duen‐Horng , Huang Yan‐Jyi
Published: January 2006

The effects of reactive poly(methyl methacrylate) (PMMA) and poly(vinyl acetate)‐block‐poly(methyl methacrylate) (PVAc‐b‐PMMA) as low‐profile additives (LPAs) on the glass‐transition temperature and mechanical properties of low‐shrink unsaturated polyester resin (UP) were investigated by an integrated approach of determining static phase characteristics, reaction kinetics, cured sample morphology, and property measurements. The factors that, according to Takayanagi mechanical models, control the glass‐transition temperature in each phase region of the cured samples, as identified by both the thermally stimulated currents method and dynamic mechanical analysis, and the mechanical properties are discussed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 867–878, 2006
Ozonolysis of model olefins—Efficiency of antiozonants
Authors: Huntink N. M. , Datta R. N. , Talma A. , Noordermeer J. W. M.
Published: January 2006

In this study, the efficiency of several potential long lasting antiozonants was studied by ozonolysis of model olefins. 2‐Methyl‐2‐pentene was selected as a model for natural rubber (NR) and 5‐phenyl‐2‐hexene as a model for styrene butadiene rubber (SBR). A comparison was made between the efficiency of conventional antiozonants like N‐(1,3 dimethylbutyl)‐N′‐phenyl‐p‐phenylene diamine (6PPD), N‐isopropyl‐N′‐phenyl‐p‐phenylene diamine (IPPD), and a mixture of diaryl p‐phenylene diamines (Wingstay 100) and some newly synthesized antiozonants. The stearic acid salt of 6PPD (PPD‐C18), 2,4,6‐tris(4‐(phenylamino)phenyl)‐1,3–5‐triazinane (ADPAT), and 4‐pyrole diphenylamine (PDPA) showed a higher efficiency than the conventional antiozonants in both NR as well as SBR model system. Special attention was paid to the carboxylic acid salts of 6PPD such as PPD‐C18, which has shown good long‐term protection of passenger tire sidewall compounds. It was demonstrated that by varying the chain length, C7, C18, and C22, of the carboxylic acid part of the 6PPD salts, the ozone protection was not influenced under the selected test conditions. The 6PPD salts made from strong acids like succinic acid (SA) and methyl sulfonic acid (MSA) appeared to be less efficient than PPD‐C18. It was also investigated whether the reactions between ozone and the double bonds of the model rubber could be measured online by a spectroscopic technique. It was demonstrated that near infrared spectroscopy is a suitable technique to study these reactions. FT Raman looked also a promising technique because of the high response factor of double bonds. However, the addition of p‐phenylene diamines (PPDAs) to the sample solution resulted in a strong discoloration (dark brown) and therefore in a high fluorescence background signal. This technique can therefore not be used for the evaluation of staining antiozonants. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 100: 853–866, 2006
Relative strength of H‐bonding groups on biodegradable polymer‐based blends in solution
Authors: Soria V. , Gomez C. M. , Falo M. , Abad C. , Campos A.
Published: January 2006

The intermolecular hydrogen bonding interactions between poly(3‐hydroxybutyrate) and poly(styrene‐co‐vinyl phenol) copolymers with mutual solvent epichlorohydrin were thoroughly investigated by steady‐state fluorescence and viscosity techniques. Fluorescence spectroscopy along with viscosity technique was used to asses the intermolecular hydrogen bonding between poly‐(3‐hydroxybutyrate) and its blends with five copolymer samples of styrene–vinyl phenol, containing different proportions of vinyl phenol but similar average molecular weight and polydispersity index. In the case of very low OH contents (2–4 mol %), as expected, both components of poly(3‐hydroxybutyrate) and poly(styrene‐co‐4‐vinylphenol) chains are well separated and remain so independently of the mixed polymer ratio and overall polymer concentration as well. Conversely, when the OH content reaches 5.8 mol % or more, a significant decrease of the intrinsic fluorescence intensity emitted by the copolymer is detected upon addition of aliquots of poly(3‐hydroxybutyrate). In these cases, an average value for the interassociation equilibrium constant, KA = 8.7, was obtained using a binding model formalism. A good agreement of these results with those obtained from complementary viscosity measurements, through the interaction parameter, Δb, was found. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 900–910, 2006
Block copolymer of trans‐polyisoprene and urethane segment: Shape memory effects
Authors: Ni Xiuyuan , Sun Xiaohui
Published: January 2006

Shape memory behaviors of trans‐polyisoprene (TPI) segmented urethane copolymers were studied. Film specimens for cyclic loading tests were prepared from the polymer solution by casting, and tested at the loading temperature of 65°C. Results show that the recovery rates of the films depend on their TPI segment contents, while the fixity rate was measured to be close to 100% for each sample. The film containing 70% TPI segments was found to show a recovery rate of 85%. Two separated phases were clearly observed in the morphology of the films. The urethane segments were organized into spherical domains acting as physical cross‐links during the shape memory process. The continuous phase formed by the crystalline TPI segments serves as the reversible phase responsible for fixation of the temporary shape. The tensile and dynamic thermal properties of those films were also studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 879–885, 2006
How to facilitate immersion in a consumption experience: appropriation operations and service elements
Authors: Carù Antonella , Cova Bernard
Published: January 2006

An entire research current has taken on the mantle of analysing the growing quest on the part of contemporary consumers for immersion into varied experiences. But there has been little empirical analysis of this process of immersion and the experience it produces. This paper introduces and develops the subjective operations that consumers undertake in their efforts to be submerged in the consumption experience. It uses empirical research based on introspective reports filed by consumers who attended a series of classical music concerts. The results suggest that, rather than being an immediate process, immersion in a consumption experience is more progressive. To facilitate this progressive process, greater attention must be paid to the management of those service elements that will have an impact on the so‐called operations of appropriation.

Copyright © 2006 John Wiley & Sons, Ltd.
Sensory stimuli and e‐tailers
Authors: Parsons Andrew , Conroy Denise
Published: January 2006

This paper examines the use of sensory stimuli in the creation of store atmosphere in the online context. Parsons (2002) shows that online shoppers are motivated by many of the same non‐functional aspects of shopping as physical store shoppers (eg Tauber, 1972; Sheth, 1983), including sensory stimulation from aural and visual stimuli. This study investigates what customers desire from a virtual store atmosphere, and conducts an audit of the 15 top e‐tailers as ranked by Nielsen/NetRatings (2001) using the extant set of stimuli/responses established from the physical store literature. Findings suggest a strong desire from customers for sensory stimuli, with only partial matching by e‐tailers, and a surprising lack of differentiation among competitors. Examination of purchase responses to actual stimuli suggests a need for e‐tailers to match consumers' desires.

Copyright © 2006 John Wiley & Sons, Ltd.
A Spirocyclic PS Cage Cation: Synthesis and Formation of P7S6I2+
Authors: Gonsior Marcin , Krossing Ingo , Matern Eberhard
Published: January 2006

Upon ionization of the P4S3I2 molecule with Ag[Al(OR)4], a highly reactive sulfonium cation P4S3I+ is generated (NMR simulated and assigned). At −80 °C this cation reacts with additional P4S3I2 to give either an iodophosphonium P4S3I3+ cation (NMR simulated and assigned) and P4S3 or to give several isomers of a metastable compound that is probably P8S3I3+. This mixture decomposes at 0 °C to give only three isomers of the spirocyclic P7S6I2+ cage cation (31P NMR simulated and assigned, X‐ray of one isomer, IR assigned). The oxidation of the [Ag(P4S3)2]+ complex by I2 also resulted in the formation of P7S6I2+, but with more by‐products. The spirocyclic 15‐atom cage of P7S6I2+ has no precedent and contains the first phosphonium center bonded only to P and S atoms. This structural element gives the first experimental clue as to how formal charge‐bearing elements in the still unknown class of binary PCh (Ch = chalcogen) or homopolyatomic P cations may be constructed.
Structural and Magnetic Properties of MnIII and CuII Tetranuclear Azido Polyoxometalate Complexes: Multifrequency High‐Field EPR Spectroscopy of Cu4 Clusters with S=1 and S=2 Ground States
Authors: Mialane Pierre , Duboc Carole , Marrot Jérôme , Rivière Eric , Dolbecq Anne , Sécheresse Francis
Published: January 2006

Two new azido‐bridged polyoxometalate compounds were synthesized in acetonitrile/methanol media and their molecular structures have been determined by X‐ray crystallography. The [{(γ‐SiW10O36)Mn2(OH)2(N3)0.5(H2O)0.5}2(μ‐1,3‐N3)]10− (1 a) tetranuclear MnIII complex, in which an end‐to‐end N3− ligand acts as a linker between two [(γ‐SiW10O36)Mn2(OH)2]4− units, represents the first manganese–azido polyoxometalate. The magnetic properties have been studied considering the spin Hamiltonian ℋ︁=−J1(S1S2+S1*S2*)−J2(S1S1*), showing that antiferromagnetic interactions between the paramagnetic centers (g=1.98) occur both through the di‐(μ‐OH) bridge (J1=−25.5 cm−1) and the μ‐1,3‐azido bridge (J2=−19.6 cm−1). The [(γ‐SiW10O36)2Cu4(μ‐1,1,1‐N3)2(μ‐1,1‐N3)2]12− (2 a) tetranuclear CuII complex consists of two [γ‐SiW10O36Cu2(N3)2]6− subunits connected through the two μ‐1,1,1‐azido ligands, the four paramagnetic centers forming a lozenge. The magnetic susceptibility data have been fitted. This reveals ferromagnetic interactions between the four CuII centers, leading to an S=2 ground state (ℋ︁=−J1(S1S2+S1*S2*)−J2(S2S2*), J1= +294.5 cm−1, J2=+1.6 cm−1, g=2.085). The ferromagnetic coupling between the CuII centers in each subunit is the strongest ever observed either in a polyoxometalate compound or in a diazido‐bridged CuII complex. Considering complex 2 a and the previously reported basal–basal di‐(μ‐1,1‐N3)‐bridged CuII complexes in which the metallic centers are not connected by other magnetically coupling ligands, the linear correlation J1=2639.5−24.95*θav between the θav bridging angle and the J1 coupling parameter has been proposed. The electronic structure of complex 2 a has also been investigated by using multifrequency high‐field electron paramagnetic resonance (HF‐EPR) spectroscopy between 95 and 285 GHz. The spin Hamiltonian parameters of the S=2 ground state (D=−0.135(2) cm−1, E=−0.003(2) cm−1, gx=2.290(5), gy=2.135(10), gz=2.158(5)) as well as of the first excited spin state S=1 (D=−0.960(4) cm−1, E=−0.080(5) cm−1, gx=2.042(5), gy=2.335(5), gz=2.095(5)) have been determined, since the energy gap between these two spin states is very small (1.6 cm−1).
Vibronic Coupling in Organic Semiconductors: The Case of Fused Polycyclic Benzene–Thiophene Structures
Authors: Coropceanu Veaceslav , Kwon Ohyun , Wex Brigitte , Kaafarani Bilal R. , Gruhn Nadine E. , Durivage Jason C. , Neckers Douglas C. , Brédas Jean‐Luc
Published: January 2006

The nature of vibronic coupling in fused polycyclic benzene–thiophene structures has been studied using an approach that combines high‐resolution gas‐phase photoelectron spectroscopy measurements with first‐principles quantum‐mechanical calculations. The results indicate that in general the electron–vibrational coupling is stronger than the hole–vibrational coupling. In acenedithiophenes, the main contributions to the hole–vibrational coupling arise from medium‐ and high‐frequency vibrations. In thienobisbenzothiophenes, however, the interaction of holes with low‐frequency vibrations becomes significant and is larger than the corresponding electron–vibrational interaction. This finding is in striking contrast with the characteristic pattern in oligoacenes and acenedithiophenes in which the low‐frequency vibrations contribute substantially only to the electron–vibrational coupling. The impact of isomerism has been studied as well.
S,O‐Acetals as Novel “Chiral Aldehyde” Equivalents
Authors: Trost Barry M. , Crawley Matthew L. , Lee Chul Bom
Published: January 2006

Palladium‐catalyzed asymmetric allylic alkylations (AAA) to form “chiral aldehyde” equivalents were investigated. α‐Acetoxysulfones were formed in high enantiomeric excess as single regioisomers in AAA reactions of allylic geminal dicarboxylates with sodium benzenesulfinate. The directing ability of this novel functional group was highlighted by a series of dihydroxylations, affording syn diols exclusively anti to the acetoxy sulfone as single diastereomers in excellent yields. This is the first example of an asymmetric dihydroxylation protocol that gives the equivalent of reaction with a simple enal. The synthetic value of this process was exemplified by subsequent transformations of the diols including the development of a one‐pot dihydroxylation–deprotective acyl migration protocol to give differentially protected 1,2‐diols.
Substrate‐Independent Transduction of Chromophore‐Free Organic and Biomolecular Transformations into Color
Authors: Das Gopal , Matile Stefan
Published: January 2006

The concept of synthetic multifunctional pores as substrate‐independent optical signal transducers of chemical reactions is introduced with emphasis on the combination with substrate‐specific signal generation in biomolecular transformations. Comparison with the general electrochemical transduction, known from conventional biosensors, and the general optical transduction of analyte‐specific biomolecular recognition (rather than transformation), known from immunosensing, reveals the fundamental nature of the concept as well as an attractive complementarity to existing methods. Examples with transferases, hydrolases, lyases, and even an isomerase demonstrate that optical transduction with synthetic multifunctional pores is general far beyond the substrate‐specific signal generators of electrochemical transduction, that is, the oxidoreductases, and absolutely unproblematic. In part very recent breakthroughs are used to highlight the remarkable promise of synthetic multifunctional pores as optical transducers of biomolecular transformation with regard to practical sensing and screening applications.
Tuning the Reaction Site for Enzyme‐Free Primer‐Extension Reactions through Small Molecule Substituents
Authors: Rojas Stütz Jan A. , Richert Clemens
Published: January 2006

The replication of genetic information relies on the template‐directed extension of DNA primers catalyzed by polymerases. The active sites of polymerases accept four different substrates and ensure fidelity and processivity for each of them. Because of the pivotal role of catalyzed primer extension for life, it is important to better understand this reaction on a molecular level. Here we present results from primer‐extension reactions performed with chemical systems that show high reactivity in the absence of polymerases. Small molecular caps linked to the 5′‐terminus of templates are shown to enhance the rate and selectivity of primer extension driven by 2‐methylimidazolides as activated monomers for any of the four different templating bases (A, C, G, and T). The most consistent effect is provided by a stilbene carboxamide residue, rather than larger aromatic or aliphatic substituents. Up to 20‐fold rate enhancements were achieved for the reactions at the terminus of the template. The preference for a medium size cap can be explained by competing interactions with both the oligonucleotides and the incoming deoxynucleotide. The data also show that there is no particularly intractable problem in combining promiscuity with fidelity. Exploratory experiments involving a longer template and a downstream‐binding strand with a 5′‐cap show up to 38‐fold rate acceleration over the same reaction templated by a single overhanging nucleotide.
Protonic and Temperature Modulation of Constituent Expression by Component Selection in a Dynamic Combinatorial Library of Imines
Authors: Giuseppone Nicolas , Lehn Jean‐Marie
Published: January 2006

The constitutional recomposition of a dynamic library of imines displays a complex behavior under the effect of two parameters, acidity and temperature. A qualitative analysis of the quantitative data is presented. The results illustrate the response of such a dynamic system to a physical stimulus (temperature) and a chemical effector (H+), thus demonstrating its adaptive behavior under the pressure of external factors. They also point to the possibility of modulating a given functional property (optical, electronic, ionic) by constitutional recomposition induced by a specific trigger. Such features are of great interest for the development of stimuli‐responsive, functional dynamic materials.
A Fluent Transition from Triiodide, I3−, to Tris(trifluoromethyltellurate)(1−), [(TeCF3)3]−—A Structural Study
Authors: Fischer Hendrik T. M. , Naumann Dieter , Tyrra Wieland
Published: January 2006

A complete series of compounds with the anions [(TeCF3)3−xIx]− (x=0–2) had been prepared and characterised in the solid state and by NMR spectroscopic methods. Dynamic behaviour in solution can be assumed for [(TeCF3)3]− and [(TeCF3)2I]−, while in the solid state all three bis(triphenylphosphoranyliden)ammonium (PNP) salts resemble structures found in triiodides. The molecular structures of [PNP][(TeCF3)3−xIx]− (x=0–2) are discussed in comparison with [PNP]I3, I2, and Te2(CF3)2. On this basis, the structures of the [(TeCF3)3]− and [(TeCF3)I2]− ions are comparable to symmetric I3− ions, while the [(TeCF3)2I]− ion resembles an asymmetric I3− unit.
Infrared Spectra and Structures of the Th(OH)2 and Th(OH)4 Molecules.
Authors: Wang Xuefeng , Andrews Lester
Published: January 2006

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Synthesis and Structure of Sr6Ge5N2 and Ba6Ge5N2.
Authors: Park Dong Gon , Gal Zoltan A. , DiSalvo Francis J.
Published: January 2006

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K‐Site Splitting in KTiOPO4 at Room Temperature.
Authors: Norberg Stefan T. , Ishizawa Nobuo
Published: January 2006

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Ca2CuTe4O10Cl2, a New Synthetic Tellurium(IV) Oxochloride.
Authors: Takagi Rie , Johnsson Mats
Published: January 2006

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Transport, Magnetic, Thermal and Structural Properties of the Spinel Compound CuTi2S4.
Authors: Okada Hironari , Koyama Keiichi , Watanabe Kazuo
Published: January 2006

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Investigation of LaMn2‐xFexSi2 (0 ≤ x ≤ 1.2) by Magnetic Measurements and Neutron Diffraction.
Authors: Dincer I. , Elmali A. , Elerman Y. , Ehrenberg H. , Fuess H. , Daoud‐Aladine A.
Published: January 2006

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Single‐Crystalline Study of the Ferromagnetic Kondo Compound UCu0.9Sb2.
Authors: Bukowski Z. , Troc R. , Stepien‐Damm J. , Sulkowski C. , Tran V. H.
Published: January 2006

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The Magnetic Structure of TlCrTe2.
Authors: Ronneteg Sabina , Lumey Marck‐Willem , Dronskowski Richard , Berger Rolf
Published: January 2006

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A Study of Pr‐Substituted Strontium Hexaferrite by Hydrothermal Synthesis.
Authors: Wang J. F. , Ponton C. B. , Harris I. R.
Published: January 2006

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Thermodynamic Properties of the Ternary Oxides in the System Sm—Ru—O
Authors: Banerjee Aparna , Prasad R. , Vaidya V. N. , Venugopal V.
Published: January 2006

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Phase Diagram of the Tb—Dy—Zn Ternary System
Authors: Wang B. W. , Cao S. Y. , Huang W. M. , Weng L. , Sun Y. , Liu W. L.
Published: January 2006

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Layered Hydrogen Titanate Nanowires with Novel Lithium Intercalation Properties.
Authors: Li Junrong , Tang Zilong , Zhang Zhongtai
Published: January 2006

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Oxygen Permeability and Stability of Sr0.95Co0.8Fe0.2O3‐δ in a CO2‐ and H2O‐Containing Atmosphere.
Authors: Yi Jianxin , Feng Shaojie , Zuo Yanbo , Liu Wei , Chen Chusheng
Published: January 2006

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Tuning Intercalation Sites in Nickel Hexacyanoferrate Using Lattice Nonstoichiometry.
Authors: Hao Xiaogang , Schwartz Daniel T.
Published: January 2006

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Systematic Study of Formation and Crystal Structure of 3d‐Transition Metal Nitrides Synthesized in a Supercritical Nitrogen Fluid under 10 GPa and 1800 K Using Diamond Anvil Cell and YAG Laser Heating.
Authors: Hasegawa Masashi , Yagi Takehiko
Published: January 2006

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High‐Temperature, High‐Pressure Hydrothermal Synthesis, Crystal Structure, and Luminescence Properties of Cs3EuSi6O15, a New Europium(III) Silicate with a Three‐Dimensional Framework Structure.
Authors: Huang Meow‐Yu , Chen Yi‐Hsiu , Chang Bor‐Chen , Lii Kwang‐Hwa
Published: January 2006

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Diphenylprolinol Methyl Ether: A Highly Enantioselective Catalyst for Michael Addition of Aldehydes to Simple Enones.
Authors: Chi Yonggui , Gellman Samuel H.
Published: January 2006

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Chiral Binaphthyl‐Derived Amine‐Thiourea Organocatalyst‐Promoted Asymmetric Morita—Baylis—Hillman Reaction.
Authors: Wang Jian , Li Hao , Yu Xinhong , Zu Liansuo , Wang Wei
Published: January 2006

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Enantioselective Organocatalytic Michael Addition of Malonate Esters to Nitro Olefins Using Bifunctional Cinchonine Derivatives.
Authors: Ye Jinxing , Dixon Darren J. , Hynes Peter S.
Published: January 2006

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Radical‐Carbanion Cyclo‐Coupling in Armed Aromatics: Overriding Steric Hindrance to Ring Closure.
Authors: Roydhouse Mark D. , Walton John C.
Published: January 2006

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Chemoselective Oxidation of Sulfides to Sulfoxides Using N‐t‐Butyl‐N‐chlorocyanamide.
Authors: Kumar Vinod , Kaushik Mahabir Parshad
Published: January 2006

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Reduction of π‐Deficient Heterocyclic Secondary Carbinols with Sodium Borohydride/Trifluoroacetic Acid
Authors: Nutaitis Charles F. , Swartz Brett D.
Published: January 2006

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Comparative Study of the Reactivity of Iodinating Agents in Solution and Solid Phase.
Authors: Krasnokutskaya E. A. , Lesina Yu. A. , Gorlushko D. A. , Filimonov V. D.
Published: January 2006

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KF/Al2O3‐Mediated Michael Addition of Thiols to Electron‐Deficient Olefins.
Authors: Moghaddam F. Matloubi , Bardajee G. Rezanejade , Veranlou R. Oftadeh Chadorneshine
Published: January 2006

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Boc‐Proctected Amines via a Mild and Efficient One‐Pot Curtius Rearrangement.
Authors: Lebel Helene , Leogane Olivier
Published: January 2006

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4‐Substituted Prolyl Sulfonamides as Enantioselective Organocatalysts for Aldol Reactions.
Authors: Bellis Evagelos , Vasilatou Konstantina , Kokotos George
Published: January 2006

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2,6‐Dicarboxypyridinium Fluorochromate: A Mild and Efficient Reagent for Oxidative Deprotection of Trimethylsilyl Ethers to Their Corresponding Carbonyl Compounds.
Authors: Hosseinzadeh Rahman , Tajbakhsh Mahmood , Ramzanian‐Lehmali Farhad , Sadatshahabi Marzieh
Published: January 2006

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Parallel Synthesis of a Library of Acylsemicarbazides Using a Solution‐Phase One‐Pot Method and Their Evaluation as Crop‐Protection Agents.
Authors: Grzyb Justyna A. , Dekeyser Mark A. , Batey Robert A.
Published: January 2006

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Aminomethylation of Organic Halides Promoted by Zinc in Protic Medium.
Authors: Estevam Idalia H. S. , da Silva Margarete F. , Bieber Lothar W.
Published: January 2006

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Rapid and Efficient Synthesis of Some Biological Active 2‐Azetidinones under Microwave Irradiation.
Authors: Desai K. G. , Desai K. R.
Published: January 2006

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A Tandem C—H Insertion—Acetal Cleavage Sequence: Stereocontrolled Synthesis of Substituted Tetrahydrofurans.
Authors: Garbi Amel , Mina John G. , Steel Patrick G. , Longstaff Tim , Vile Sadie
Published: January 2006

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An Efficient Stereoselective Synthesis of 4,5‐trans‐1,5‐cis‐3‐Oxabicyclo[3.1.0]hexan‐2‐ones via the Iodolactonization of Alkylidenecyclopropyl Esters.
Authors: Ma Shengming , Lu Lianghua
Published: January 2006

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An Efficient Synthesis of 5‐Silyl‐2,3‐dihydrofurans via Acid‐Catalyzed Ring‐Enlargement of Cyclopropyl Silyl Ketones and Their Functionalization.
Authors: Honda Mitsunori , Naitou Tomoyuki , Hoshino Hiromitsu , Takagi Seiji , Segi Masahito , Nakajima Tadashi
Published: January 2006

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High‐Temperature Synthesis of Thiophene from Bis(2‐chloroethyl) Sulfide.
Authors: Voronkov M. G. , Levanova E. P. , Sukhomazova E. N. , Russavskaya N. V. , Deryagina E. N. , Korchevin N. A.
Published: January 2006

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Asymmetric Halo‐Mannich‐Type Reaction Provides Access to Pyrrolidines and β‐Proline Derivatives.
Authors: Timmons Cody , Guo Li , Liu Junying , Cannon John F. , Li Guigen
Published: January 2006

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New Reactivity Patterns in Activated Indoles with 2‐Methyl Substituents.
Authors: Jones Ashley W. , Wahyuningsih Tutik Dwi , Pchalek Karin , Kumar Naresh , Black David StC.
Published: January 2006

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Novel Indole α‐Methylene‐γ‐lactones as Potent Inhibitors for AKT‐mTOR Signaling Pathway Kinases.
Authors: Ding Huasheng , Zhang Chao , Wu Xihan , Yang Chunhao , Zhang Xiongwen , Ding Jian , Xie Yuyuan
Published: January 2006

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New Tricyclic Amides. Synthesis, Structure, and Oxidation with Peroxyphthalic Acid.
Authors: Kas'yan L. I. , Okovityi S. I. , Tarabara I. N. , Kas'yan A. O. , Bondarenko Ya. S.
Published: January 2006

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Palladium‐Catalyzed Amination and Amidation of Benzo‐Fused Bromine‐Containing Heterocycles.
Authors: Sergeev A. G. , Artamkina G. A. , Velezheva V. S. , Fedorova I. N. , Beletskaya I. P.
Published: January 2006

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Nickel‐Catalyzed Coupling of Isocyanates with 1,3‐Iodoesters and Halobenzenes: A Novel Method for the Synthesis of Imide and Amide Derivatives.
Authors: Hsieh Jen‐Chieh , Cheng Chien‐Hong
Published: January 2006

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A Route to Annulated Indoles via a Palladium‐Catalyzed Tandem Alkylation/Direct Arylation Reaction.
Authors: Bressy Cyril , Alberico Dino , Lautens Mark
Published: January 2006

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Novel 3,4‐Diarylpyrazolines as Potent Cannabinoid CB1 Receptor Antagonists with Lower Lipophilicity.
Authors: Lange Jos H. M. , van Stuivenberg Herman H. , Veerman Willem , Wals Henri C. , Stork Bob , Coolen Hein K. A. C. , McCreary Andrew C. , Adolfs Tiny J. P. , Kruse Chris G.
Published: January 2006

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Convenient Method for the Preparation of 2‐Aryl‐1H‐benzimidazole‐4‐carboxylic Acids
Authors: Cheng Jun , Xiu Naiyun , Li Xiangbin , Luo Xianjin
Published: January 2006

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Versatile Access to C‐4‐Substituted 2‐Amino‐1,3‐azoles from Hydropyridines in Oxidative Conditions.
Authors: del Rayo Sanchez Salvatori Maria , Abou‐Jneid Robert , Ghoulami Said , Martin Marie‐Therese , Zaparucha Anne , Al‐Mourabit Ali
Published: January 2006

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New Tandem Reactions of Metal Carbenoids. Intermolecular Formation of Azomethine Ylide from Methyl 2‐Diazo‐2‐phenylacetate and Schiff Base: Intramolecular 1,3‐Dipolar Cycloaddition.
Authors: Khlebnikov A. F. , Novikov M. S. , Bespokoev A. A. , Kostikov R. R. , Kopf J. , Starikova Z. A. , Antipin M. Yu.
Published: January 2006

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Ring‐Closing Metathesis for the Synthesis of 2H‐ and 4H‐Chromenes.
Authors: van Otterlo Willem A. L. , Ngidi E. Lindani , Kuzvidza Samuel , Morgans Garreth L. , Moleele Simon S. , de Koning Charles B.
Published: January 2006

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Thiophene‐Fused Quinoline Analogues: Facile Synthesis of 3‐Amino‐2‐cyanothieno[2,3‐b]quinolines from 2‐Chloro‐3‐cyanoquinolines.
Authors: Srivastava Ambika , Chandra Atish , Singh R. M.
Published: January 2006

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Synthesis of [1,2,4]Triazolo[1,5‐a]pyrazines as Adenosine A2A Receptor Antagonists.
Authors: Dowling James E. , et al. et al.
Published: January 2006

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