bluuebunny/crossref_metadata_2025_split huggingface dataset:
A kinetic study of novel bimetallic titanocene catalyst for syndiospecific styrene polymerization
Authors: Yim Jin‐Heong , Young Cho Kuk 
Published: March 2007

AbstractA kinetic study of a syndiospecific polymerization was performed with two kinds of catalysts: Cp*Ti(O(C6H4)CMe2(C6H4)O)TiCp* [bimetallic system] and Cp*Ti(OMe)3 [monometallic system]. The purpose of this study was to determine the reasons behind the high activity of a bimetallic catalyst system. The active site structures of the two kinds of catalysts appears to be similar to the cationic Ti [III] species having η5‐pentamethylcyclopentadienyl ligand, while the rate of the activation process of the bimetallic catalyst was found to be higher than that of the monometallic catalyst. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Shear and elongational rheology of polyethylenes with different molecular characteristics. I. Shear rheology
Authors: Wei X. , Collier J. R. , Petrovan S. 
Published: March 2007

AbstractFour metallocene polyethylenes (PE), one conventional low density polyethylene (LDPE), and one conventional linear low density polyethylene (LLDPE) were characterized in terms of their complex viscosity, storage and loss moduli, and phase angle at different temperatures. The effects of molecular weight, breadth of molecular weight distribution, and long‐chain branching (LCB) on the shear rheological properties of PEs are studied. For the sparsely long‐chain branched metallocene PEs, LCB increases the zero‐shear viscosity. The onsets of shear thinning are shifted to lower shear rates. There is also a plateau in the phase angle, δ, for these materials. Master curves for the complex viscosity and dynamic moduli were generated for all PE samples. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Flame retardancy and mechanical properties of EVA nanocomposites based on magnesium hydroxide nanoparticles/microcapsulated red phosphorus
Authors: Lv Jian‐ping , Liu Wen‐hong 
Published: March 2007

AbstractThe flame retardancy and mechanical properties of ethylene vinyl acetate (EVA) polymer nanocomposite based on magnesium hydroxide (MH) nanoparticles with lamellar‐shape morphological structures and synergistic agent microcapsulated red phosphorus (MRP) have been studied by limiting oxygen index (LOI), cone calorimeter test (CCT), UL‐94 test, tensile strength (TS), and elongation at break (EB). Results showed that LOI values of lamellar‐like nanosized MH (50 × 350 nm2) samples were 1–7 vol. % higher than those of the common micrometer grade MH (1–2 μm) in all additive levels. When 1–3 phr MRP substituted for nanosized MH filler, LOI value increased greatly from original 37 to 55, and met the V‐0 rating in the UL‐94 test. The values of TS for MH nanoparticles composites increased from 10.4 to 17.0 MPa as additive loading levels increased from 80 to 150 phr, respectively, while the corresponding values for common micrometer MH composites decreased steadily from 9.7 to 7.1 MPa. Thermogravimetric analysis (TGA) and dynamic Fourier‐transform infrared spectroscopy (FTIR) results revealed two‐step flame‐retardant mechanism. First, MH particles decompose endothermically with the release of 30.1% hydration water in the 320–370°C temperature range. Second, MRP promote the formation of compact charred layers slowly in the condensed phase in the 450–550°C temperature range. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
New photochemical approach to cellulose fabric and photoinitiator system
Authors: Han Samsook , Lee Muncheul 
Published: March 2007

AbstractThe surface modifications of cellulose substrate based on the photo‐induced reaction are closely related with the radicals introduced on the surface of cellulose substrates by light irradiation. We have evaluated the ability of radical formation in lyocell fabric and two water‐soluble photoinitiator systems by using photoluminescence analyses. Namely, the relative quantum yields of fluorescence and phosphorescence were estimated by the integrated emission intensity under the same values of light absorbance and the identical measuring conditions. First of all the [2‐(acryloyloxy)ethyl](4‐benzoylbenzyl)dimethylammonium bromide (PIA) system had larger UV absorbance values below 287 nm than [3‐(3,4‐dimethyl‐9‐oxo‐9h‐thioxanthene‐2‐yloxy)‐2‐hydroxypropyl]trimethylammonium chloride (PIB) system at the same concentration. The relative quantum yields of fluorescence and phosphorescence emission in PIA system were smaller than those in PIB system even if the two systems had the same values of light absorbance. Therefore it was found that the PIA system was more easily transited to the triplet‐state and the transited molecules reacted with the cellulose substrates more effectively. The modified cellulose fabric with 2‐(dimethylamino)ethyl chloride hydrochloride (AM1) and PI system had only a little different UV absorbance and photoluminescence properties from the untreated fabric system. However, the fabric modified with 2‐(4‐chlorophenyl)‐ethylamine (AM2) and PI system showed relatively big differences. The UV absorbance values were increased and the relative quantum yields of photoluminescence were decreased remarkably. We have acquired that the tertiary amine treated cellulose fabric were very effective in photo‐induced modification of cellulose. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Surface modification of a group of polymers using a low temperature cascade arc torch
Authors: Gilliam Mary , Yu Qingsong 
Published: March 2007

AbstractSurface modification treatments were performed on six different types of polymers using low temperature cascade arc torch (LTCAT) of Ar with or without adding reactive gas of O2 or H2O vapor. The effects of the treatments on the wettability enhancement, surface degradation from oligomer formation, and surface stability from the mobility of surface moieties and hydrophobic recovery were investigated. Surface characterization techniques included the static Sessile droplet method and dynamic Wilhelmy balance method. Experimental results indicated that Ar LTCAT treatments of the polymers with shorter treatment times (2 s in most cases) resulted in stable and hydrophilic surfaces without any surface damage from oligomer formation, with the exception of nylon‐6. The excellent results from Ar LTCAT treatments were attributed to the CASING effect (crosslinking via activated species of inert gas). Addition of O2 into Ar LTCAT resulted in greater wettability of the treated surfaces, but increased surface damage from oligomer formation. Adding H2O vapor into Ar LTCAT produced extremely hydrophilic surfaces on the polymers, but pronounced surface damage. The surface oligomer formation was attributed to alkoxy degradation reactions and chain scission from overexposure to high energy species. Comparisons of the treatment outcomes for each type of polymer are discussed with respect to the degree of wettability enhancement, the stability of the treated surfaces, and the susceptibility to degradation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Personal digital assistant (PDA) cell phone units produce elevated extremely‐low frequency electromagnetic field emissions
Authors: Sage Cindy , Johansson Olle , Sage S. Amy 
Published: March 2007

AbstractInitial tests indicate that personal and occupational use of personal digital assistants (PDAs or palm‐held wireless units) produce high intensity bursts of extremely‐low frequency electromagnetic fields (ELF‐EMF). These emissions could result in comparatively high ELF‐EMF exposure in persons that carry a PDA close to the body (i.e., in a pocket or on a belt); or held to the head for cell phone conversations. ELF‐EMF emissions of 10 µT were recorded on PDAs during normal office use over a 24 h test period. Results of ELF‐EMF measurements show that email transmit and receive functions produce rapid, short‐duration ELF‐EMF spikes in the 2–10 µT range, each lasting several seconds to over a minute apparently depending on file download size. Some units produced spikes as high as 30–60 µT during email activities. Cell phone activity on PDAs produced continuously elevated ELF‐EMF readings in the 0.5–1 µT range, as opposed to the rapid spiking pattern for email receipt and transmission. Switching the PDA unit from “OFF” to “ON” position resulted in single ELF‐EMF pulses of over 90 µT on two units. Email downloads into the PDA can occur randomly throughout the day and night when the unit is “ON”; thus the user who wears the PDA may be receiving high‐intensity ELF‐EMF pulses throughout the day and night. The frequency of email traffic on the PDA, and the power switching unit (battery unit) may affect the frequency and intensity of ELF‐EMF emissions. Bioelectromagnetics 28:386–392, 2007. © 2007 Wiley‐Liss, Inc.
The vertebral nerve revisited
Authors: Tubbs R. Shane , Loukas Marios , Remy Allison C. , Shoja Mohammadali M. , Salter E. George , Oakes W. Jerry 
Published: March 2007

AbstractThere is significant paucity in the literature regarding the vertebral nerve. Moreover, descriptions of this structure are conflicting. To evaluate further the anatomy and potential clinical significance of this structure, 10 fresh adult cadavers (20 sides) underwent dissection and macroscopic observation of this structure. All specimens were found to have a vertebral nerve that originated from the stellate ganglion with the exception of two left sides (10%) in which this nerve arose from the inferior cervical ganglion. This nerve ascended posteromedial to the vertebral artery. The vertebral nerve was found to be, in essence, a long and deep gray ramus communicans that connected most commonly the stellate ganglia to C6 or C7 spinal nerves by passing through the C6 and C7 transverse foramina. Fifteen percent of sides were found to have a vertebral nerve that was plexiform in its configuration. Fifty percent were found to have very small branches that entered the fibrous capsule of adjacent zygapophyseal and intervertebral joints. Some specimens were noted to have meningeal branches of the vertebral nerve. Based on our observations, the vertebral nerve is simply a deep ramus communicans, which often provides articular and meningeal branches to the adjacent spine. As neck pain is a significant reason for physician office visits, additional knowledge of the nerves innervating the joints and adjacent meninges of the neck could be important for both surgical and medical blockade of nerve fibers. Clin. Anat. 20:644–647, 2007. © 2007 Wiley‐Liss, Inc.
Variation of the spinal nerve compositions of thoracodorsal nerve
Authors: Lee Kyu‐Seok 
Published: March 2007

AbstractThoracodorsal nerve distributes to the latissimus dorsi muscle. The aim of this study was to investigate the anatomic variation of the spinal nerve compositions of thoracodorsal nerve and to confirm which spinal nerve is a main component in participating amount. The most frequent type was consisted of C7 and C8 in 60%. Next frequent type was C6, C7, and C8 in 25%. Third type was C6 and C7 in 10% and fourth type was C7 alone in 5%. The diameter of each spinal nerve comprising thoracodorsal nerve was 1.20 ± 0.23 (mean ± SD) mm at C7, 0.43 ± 0.15 mm at C8, and 0.33 ± 0.09 mm at C6. These results show that the C7 nerve was the main component of thoracodorsal nerve and the anatomic variation appeared at the spinal nerve that participate by small amounts, as be excepted (C6 and C8). Clin. Anat. 20:660–662, 2007. © 2007 Wiley‐Liss, Inc.
An integrative approach to the treatment of hyperhidrosis: review and case study
Authors: Kraft Tom , Kraft David 
Published: March 2007

AbstractA review of the world literature indicates that there is a multiplicity of treatment approaches for hyperhidrosis. Most of these concentrate on the symptom itself and range from topical applications to sympathectomy. This paper demonstrates the value of an integrative approach in which behaviour therapy, combined with hypnosis, is used in conjunction with psychodynamic psychotherapy. This is a case study of a 58‐year‐old single man who, due to his severe social anxiety, had suffered from excessive sweating throughout his life. The dual approach to treatment concentrates both on the hyperhidrosis as well as its causation. The patient made an excellent recovery and this was maintained over a two year period. Copyright © 2007 British Society of Experimental & Clinical Hypnosis. Published by John Wiley & Sons, Ltd.
The value of using hypnosis in helping an adult survivor of childhood sexual abuse
Authors: Poon Maggie Wai‐ling 
Published: March 2007

AbstractThis report describes the successful treatment of a 33‐year‐old Chinese woman who had affect dysregulation and chronic trauma symptoms resulting from an intra‐familial childhood sexual abuse. A strategically phased multimodal treatment tailored to the needs of the client was used. The treatment framework consisted of three phases: training on affect management, strengthening the ego and re‐processing the trauma. Hypnosis was utilized as a means for grounding and stabilizing the overwhelming emotions; for addressing the negative self‐schema; and also for re‐processing the traumatic memories in a safe and controlled way. Data from self‐reports, observation and objective measures indicates a significant reduction in the trauma symptoms. Copyright © 2007 British Society of Experimental & Clinical Hypnosis. Published by John Wiley & Sons, Ltd.
Intramolecular Hydroamination/Cyclisation of Aminoallenes Mediated by a Neutral Zirconocene Catalyst: A Computational Mechanistic Study
Authors: Tobisch Sven 
Published: March 2007

AbstractThe complete catalytic cycle for the intramolecular hydroamination/cyclisation (IHC) of 4,5‐hexadien‐1‐ylamine (1) by a prototypical [ZrCp2Me2] precatalyst (2) has been scrutinized by employing a reliable DFT method. The present study conducted by means of a detailed computational characterisation of structural and energetic aspects of alternative pathways for all of the relevant elementary steps complements the mechanistic insights revealed from experimental results. The operative mechanism entails an initial transformation of precatalyst 2 into the thermodynamically prevalent, but dormant, bis(amido)–Zr compound in the presence of aminoallene 1. This complex undergoes a reversible, rate‐determining α‐elimination of 1 to form the imidoallene–Zr complex. The substrate‐free form, which contains a chelating imidoallene functionality, is the catalytically active species and is rapidly transformed into azazirconacyclobutane intermediates through a [2+2] cycloaddition reaction. This highly facile process does not proceed regioselectively because the alternative pathways for the formation of five‐ and six‐membered azacycles have comparable probabilities. Degradation of cyclobutane intermediates by following the most feasible pathway occurs through protonolysis of the metallacycle moiety and subsequent proton transfer from the ZrNHR moiety onto the azacycle. The five‐membered allylamine is generated through protonation at carbon atom C6 followed by α‐hydrogen elimination, whereas protonolysis of the cyclobutane moiety at the ZrN bond followed by proton transfer onto carbon atom C5 is the dominant route for the six‐membered product. Of the two consecutive proton transfer steps, the second one determines the overall kinetics of the entire protonation sequence. This process is predicted to be substantially slower than the cycloaddition reaction. The factors that regulate the composition of the cycloamine products have been elucidated.
Discussion on the Formation and Bonding in Three [Ga8R10] Compounds: The Diversity in Classical GaGa Bonds
Authors: Hartig Jens , Steiner Jochen , Stößer Anna , Schnöckel Hansgeorg 
Published: March 2007

AbstractHerein we describe three Ga8 compounds that feature gallium atoms in an oxidation state of 1.25 with normal valent 2e–2c bonding. Their structures and the influence of their ligands (phosphorus and nitrogen atoms directly bonded to the Ga8 moieties) are discussed on the basis of DFT calculations, providing an insight into a probable mechanism for insertion reactions between GaX and GaX3 species that lead to a reaction cascade via halides like Ga2X4 and Ga5X7 to Ga8X10 and Ga8X122−, respectively. Finally, the Ga8 cores of the three title compounds were compared with the topology of carbon atoms in C8 alkanes.
Asymmetric Synthesis of Antimicrotubule Biaryl Hybrids of Allocolchicine and Steganacin
Authors: Joncour Agnès , Décor Anne , Liu Jian‐Miao , Tran Huu Dau Marie‐Elise , Baudoin Olivier 
Published: March 2007

AbstractThe asymmetric synthesis of novel axially chiral biaryl compounds 5 a–f containing a seven‐ or eight‐membered heterocyclic medium ring is described. These molecules can be considered to be structural hybrids of allocolchicine‐ and steganacin‐type natural products. The synthesis featured an atropo–diastereoselective biaryl Suzuki coupling in which a benzylic stereocenter efficiently transferred its stereochemical information to the biaryl axis. The coupling conditions were optimized, and two biphenylphosphane ligands (DavePhos and S‐Phos) were found to give the highest yields and diastereoselectivities. A three‐element stereochemical model was proposed to explain the observed diastereoselectivities. In a second key step, the medium ring of the target molecules was formed by a stereoselective SN1‐type cyclodehydration that probably involved a configurationally stable carbocationic intermediate, as supported by calculations. Alternatively, SN2‐type cyclizations were employed on the same Suzuki coupling products to give the target molecules in a stereodivergent or stereoconvergent manner. These cyclization methods furnished the target hybrid analogues 5 a–f with ee values above 94 %. All analogues were evaluated as antimicrotubule agents and against a panel of cancer‐cell lines using colchicine (1) and N‐acetylcolchinol (3) as references. Promising activities were found for R,aR‐configured compounds 5 a, b and 5 f; in particular, ethyl analogue 5 b showed a twofold antimicrotubule activity relative to colchicine.
GC‐MS detection of chiral markers in cocoa beans of different quality and geographic origin
Authors: Caligiani Augusta , Cirlini Martina , Palla Gerardo , Ravaglia Roberta , Arlorio Marco 
Published: March 2007

AbstractFermented cocoa beans (Theobroma cacao L., Sterculiaceae) from different countries of origin (Ecuador, Ghana, Trinidad) and cocoa beans roasted under defined conditions (industrial roasting; 150–220°C for 20 min, dry roasting in conventional oven) were analyzed for their contents of certain chiral hydroxy acids, catechins, and amino acids. Cocoa beans are fermented, dried, and industrially transformed by roasting for the production of chocolate, cocoa powders, and other cocoa‐related products. Fermentation and roasting conditions influence the contents of chiral compounds such as hydroxy acids, amino acids, and polyphenols, depending on technological procedures as well as some technical parameters. The aim of this work was to check if the content and nature of the named chiral compounds present both in fermented and roasted cocoa beans could be related to the traditional parameters used to classify the variety of seeds and the degree of fermentation. The extent of racemization of amino acids in fermented cocoa beans was low while it slowly increased during roasting, depending on the temperature applied. L‐lactic acid was always higher than the D‐form while citric acid was generally the most abundant hydroxy acid detected in beans. A correlation was found between polyphenol content and degree of fermentation, while epimerization of (−)‐epicatechin to (+)‐catechin was observed during roasting. On the whole, results showed that several chiral compounds could be considered as good quality markers for cocoa seeds and cocoa‐related products of different quality and geographic origin. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Comparative HPLC enantioseparation of ferrocenylalcohols on two cellulose‐based chiral stationary phases
Authors: Patti Angela , Pedotti Sonia , Sanfilippo Claudia 
Published: March 2007

AbstractThe direct HPLC enantiomeric separation of several ferrocenylalcohols on the commercially available Chiralcel OD and Chiralcel OJ columns has been evaluated in normal‐phase mode. Almost all the compounds were resolved on one or both chiral stationary phases (CSPs) with separation factor (α) ranging from 1.06 to 2.88 while the resolution (Rs) varied from 0.63 to 12.70 In the separation of the α‐ferrocenylalcohols 1a–e and the phenyl analogues 2a–e, which were all resolved except 1c, a similar trend in the retention behavior for the two series of alcohols was evidenced and the selectivity was roughly complementary on the two investigated CSP. For three ferrocenylacohols, chosen as model compounds, the influence of the mobile phase composition and temperature on the enantioseparation were investigated and additional information on the chiral recognition mechanism were deduced from the chromatographic behavior of their acetylderivatives. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Easily recyclable chiral polymeric Mn(III) salen complexes for oxidative kinetic resolution of racemic secondary alcohols
Authors: Kureshy Rukhsana I. , Ahmad Irshad , Pathak Kavita , Khan Noor‐Ul H. , Abdi Sayed H. R. , Prathap Jaya K. , Jasra Raksh V. 
Published: March 2007

AbstractChiral polymeric Mn(III) salen complexes were used efficiently for oxidative kinetic resolution of racemic secondary alcohols at room temperature. High chiral purity (ee; >99%) was achieved for the oxidative kinetic resolution of racemic secondary alcohols with 0.6 mol % catalyst loading in 60 min. The catalyst was easily recycled for five successive catalytic experiments. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Log‐domain linear transformation filters revised: improved building blocks and comparison results
Authors: Psychalinos Costas 
Published: March 2007

AbstractA method for designing high‐order log‐domain filters has already been proposed in the literature based on the concept of the classical linear transformation (LT) filters. For this purpose, a substitution table containing the log‐domain LT equivalent of each passive element has been introduced. Drawbacks of the log‐domain filter topologies derived according to this table are the following: (a) a dc offset current appears at the output of all pole filters and (b) dc instability is observed in the case of the substitution of LC resonators. In addition, an alternative technique already proposed for simulating filters with LC resonators is valid only under small‐signal conditions. In order to overcome the aforementioned problems, new log‐domain LT equivalents of a number of passive elements are introduced in this paper. The correct operation of the novel blocks has been verified through simulation results. Also, a comparison concerning the behaviour of the log‐domain LT filters and that of the filters derived according to the leapfrog and the wave methods has also been performed. Copyright © 2007 John Wiley & Sons, Ltd.