bluuebunny/crossref_metadata_2025_split huggingface dataset:
A DFT study of transition structures and reactivity in solvolyses of tert‐butyl chloride, cumyl chlorides, and benzyl chlorides
Authors: Ruff Ferenc , Farkas Ödön 
Published: December 2007

AbstractDFT computations were performed on the SN1 and SN2 solvolyses of substituted cumyl chlorides and benzyl chlorides in ethanol and water, by increasing stepwise the CCl distance and by optimization. The total energy increases with the increase in the ClC distance in SN1 reactions, while free energy of activation pass through maximum. To validate the results, the calculated free energies of activation were compared with data obtained by kinetic measurements. The structural parameters of the transition states were correlated with the Hammett substituent constants and compared with the data of hydrolyses of tert‐butyl chloride and methyl chloride, which proceed with known mechanisms. Conclusions on the mechanisms of the reactions were driven from the effect of substituents on free energies of activation. Cumyl chlorides substituted with electron‐donating (e‐d) groups solvolyze with SN1 mechanism, while the reactions of substrates that bear electron‐withdrawing groups proceed with weak nucleophilic assistance of the solvent. Benzyl chlorides hydrolyze through an SN2 pathway except those derivatives that have strongly e‐d groups, where the reaction has SN1 character, but a weak nucleophilic assistance of the water should also be taken into consideration. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis of poly(ethyl acrylate) by single electron transfer‐degenerative chain transfer living radical polymerization in water catalyzed by Na2S2O4
Authors: Coelho Jorge F. J. , Carvalho Erica Y. , Marques Dina S. , Popov Anatoliy V. , Percec Virgil , Gonçalves Pedro M. F. O. , Gil M. H. 
Published: December 2007

AbstractLiving radical polymerization of ethyl acrylate was achieved by single‐electron‐transfer/degenerative‐chain transfer mediated living radical polymerization in water catalyzed by sodium dithionite. The plots of number‐average molecular weight versus conversion and ln[M]0/[M] versus time are linear, indicating a controlled polymerization. This method leads to the preparation of α,ω‐di(iodo)poly(ethyl acrylate) (α,ω‐di(iodo)PEtA) macroinitiator that can be further functionalized. The molecular weight distributions were determined using a combination of three detectors (TriSEC): right‐angle light scattering, a differential viscometer and refractive index. The method studied in this work represents a possible route to prepare well‐tailored macromolecules made of ethyl acrylate in environmental friendly reaction medium. To the best of our knowledge there is no previous report dealing with the synthesis of PEtA by any LRP approach in aqueous medium. Furthermore, the method described in this article was successfully applied in pilot scale reactions under industrial production conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 421–432, 2008
Appreciable norbornene incorporation in the copolymerization of ethylene/norbornene using titanium catalysts containing trianionic N[CH2CH(Ph)O]33− ligands
Authors: Sudhakar Padmanabhan 
Published: December 2007

AbstractThe newly synthesized 1‐TiCl (C3 symmetric) and 2‐TiCl (Cs symmetric) precatalysts in combination with MAO polymerized ethylene, cyclic olefins, and copolymerized ethylene/norbornene in good yields. The catalyst with C3 symmetry exhibits moderate catalytic activity and efficient norbornene incorporation for E/NBE copolymerization in the presence of MAO [activity = 360 kg polymer/(mol Ti h), ethylene 1 atm, NBE 5 mmol/mL, 10 min], affording poly(ethylene‐co‐NBE)s with high norbornene contents (42.0%) and the Cs symmetric catalyst showed an activity of 420 kg polymer/(mol Ti h), ethylene 1 atm, NBE 5 mmol/mL affording poly(ethylene‐co‐NBE)s with 33.0% norbornene content. The effect of monomer concentration at ambient temperature and constant Al/Ti ratio for the homo and copolymerization was studied in a detailed manner. We found that apart from the electronic environment around the metal center the steric environment provided by the symmetry of the catalyst systems has a considerable influence on the percentage of norbornene content of the copolymer obtained. We also found that with a given catalyst a variable clearly influencing the copolymer microstructure, hence also the copolymer properties, is the monomer concentration at a given feed ratio. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 444–452, 2008
Specific stimuli‐responsive antipolyelectrolyte swelling of amphiphilic gel based on methacryloxyethyl dimethyloctane ammonium bromide
Authors: Xu Ling , Zhai Maolin , Huang Ling , Peng Jing , Li Jiuqiang , Wei Genshuan 
Published: December 2007

AbstractAn amphiphilic electrolyte, methacryloxyethyl dimethyloctane ammonium bromide (MODAB), was synthesized by quaternization of dimethylaminoethyl methacrylate (DMAEMA) with 1‐bromooctane. Then amphiphilic PMODAB gel was synthesized by radiation cross‐linking with ethyleneglycol dimethacrylate as cross‐linker. PMODAB gels possess distinguished different swelling behaviors with those of DMAEMA hydrogels: (1) Antipolyelectrolyte phenomenon was observed in NaCl solution, that is, a remarkable increment of equilibrium degree of swelling (EDS) in the low NaCl concentration region (10−4 to 10−3 mol L−1), followed by a significant decrease (10−3 to 0.2 mol L−1), and a collapsed state (>0.2 mol L−1); (2) Compared with PDMAEMA, PMODAB was a temperature‐sensitive polymer which showed an upper critical solution temperature (UCST) behavior. The EDS of PMODAB gel dramatically increased at the UCST; (3) In the 0.2 mol L−1 NaCl solutions, PMODAB gel swelled more significantly in a basic condition (pH > 10) than that in an acidic condition. The special volume phase transition behavior of PMODAB gel is ascribed to the hydrophobic interaction between octyl groups and the formation of ion‐cluster between tetra‐alkyl ammonium cation and Br−, which lead to the aggregation of gel structure and could be affected by the composition and temperature of the surrounding solution. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 473–480, 2008
Monodispersed PEG‐b‐PSt nanoparticles prepared by atom transfer radical emulsion polymerization under microwave irradiation
Authors: Xu Zushun , Hu Xiaoxi , Li Xiaoqin , Yi Changfeng 
Published: December 2007

AbstractAtom transfer radical emulsion polymerization of styrene using PEG‐Cl as macroinitiator under microwave irradiation was successfully conducted and monodispersed nanoparticles were prepared. The PEG‐Cl macroinitiator was synthesized, and confirmed by FTIR spectrum. The structure of the PEG‐b‐PSt diblock copolymer was characterized by 1H‐NMR and the number of styrene unit in the diblock copolymer was calculated. The morphology, size, and size distribution of the nanoparticles were characterized by transmission electron microscope (TEM) and photon correlation spectroscopy (PCS). The effects of the ratio of macroinitiator and monomer, the ratio of catalyst and macroinitiator on the size and size distribution of nanoparticles were investigated. It was found that the diameters of PEG‐b‐PSt nanoparticles prepared under microwave irradiation were smaller (<50 nm) and more monodispersed than those prepared with conventional heating. Moreover, with the increasing of the ratio of St/PEG‐Cl, the hydrodynamic diameters (Dh) of the nanoparticles increased and the poly index decreased, both Dh and poly index of the nanoparticles prepared under microwave irradiation were smaller then those prepared with conventional heating; as the concentration of catalyst increased, the Dh of the nanoparticles decreased and the poly index of the nanoparticles increased. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 481–488, 2008
Luminescence properties of soluble 2,2′,7,7′‐Tetrakis(2‐(9‐hexyl‐9H‐carbazol‐3‐yl)‐vinyl)‐9,9′‐spirobifluorene‐labeled dendrimers: Photoluminescence and electroluminescence
Authors: Kim Hong Suk , Cho Min Ju , Jung Kyung Moon , Yu Young‐Jun , Park Young Woo , Jin Jung‐Il , Choi Dong Hoon 
Published: December 2007

AbstractNew light emitting dendrimers were synthesized by reacting 3,5‐bis‐(3,5‐bis‐benzyloxy‐benzyloxy)‐benzoic acid or 3,5‐bis‐[3,5‐bis‐(3,5‐bis‐benzyloxy‐benzyloxy)‐benzyloxy]‐benzoic acid with a carbazolyl vinyl spirobifluorene moiety. A blue‐emitting core dye was encapsulated by multibenzyloxy dendrons, and two dendrimers having different densities of dendrons were prepared. Photoluminescence (PL) studies of the dendrimers demonstrated that at the higher density of benzyloxy dendrons, the featureless vibronic transitions were improved, causing lesser excimer emission. The similarity of the solution and solid emission spectra of the larger dendrimer, 10, revealed the suppression of molecular aggregation in the solid film, which is attributed to the presence of the bulky benzyloxy dendrons. The electroluminescence spectra of multilayered devices made using 10 predominantly exhibited blue emissions; similar emission was observed in the PL spectra of its thin film. The multilayered devices made using 3, 9, and 10 showed luminances of 1021 cd m−2 at 5 V, 916 cd m−2 at 6 V, and 851 cd m−2 at 6.5 V, respectively. The largest dendrimer, 10, bearing a greater number of benzyloxy dendrons, exhibited a blue‐like emission with CIE 1931 chromaticity coordinates of x = 0.16 and y = 0.13, which is due to the influence of a higher shielding effect. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 501–514, 2008
Preparation of MEH‐PPV/nanosized titania hybrids via in situ sol–gel reaction of titanium alkoxide: Optical property
Authors: Chen Hung‐Jen , Wang Leeyih , Chiu Wen‐Yen 
Published: December 2007

AbstractHomogenously dispersed organic (MEH‐PPV)/inorganic (nanosized titania) hybrids were successfully synthesized. The method of preparation was based on a simple one‐step in situ sol–gel technique using titanium isopropoxide (TIP) as the precursor. The key benefit of this preparation was that TIP interacted with both 2‐chlorophenol and MEH‐PPV, so that the degree of aggregation and phase separation could be kept to a minimum with a suitable recipe. MEH‐PPV/TIP/H2O/2‐chlorophenol of various weight ratios were synthesized to examine the morphology as well as optical properties of the MEH‐PPV/TIP(titania) hybrid. The observation of MEH‐PPV gelation and Fourier transform infrared results verified the interaction existing between MEH‐PPV and TIP. SEM photographs showed that TIP(titania) were homogenously dispersed in the MEH‐PPV film if the hybrid solution was clear from the use of a suitable recipe. UV–vis absorption measurements showed that the addition of TIP decreased the conjugation length of MEH‐PPV. A redshift in the photoluminescence (PL) emission was observed in almost all the hybrids in the solution state, because of the aggregation of MEH‐PPV. However, it was found that spinning destroyed the aggregation of MEH‐PPV, resulting in a blueshift in the PL emission of the hybrids. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 515–529, 2008
Copolymers of 4‐(1‐methyl‐1‐mesityl‐3‐cyclobutyl)‐2‐N‐1, 3‐thiazole‐2‐yl methacrylamide with 2‐[(5‐methylisoxazol‐3‐yl) amino]‐2‐oxo‐ethyl methacrylate: Synthesis, characterization, monomer reactivity ratios and biological activity
Authors: Erol Ibrahim , Dedelioglu Ayşe 
Published: December 2007

AbstractThe free radical copolymerization of 4‐(1‐methyl‐1‐mesityl‐3‐cyclobutyl)‐2‐N‐1, 3‐thiazole‐2‐yl methacrylamide (MCTMA) with 2‐[(5‐methylisoxazol‐3‐yl)amino]‐2‐oxo‐ethyl methacrylate (IAOEMA) has been carried out in 1, 4‐dioxane at 65 °C ± 1 and were analyzed by Fourier transform infrared, 1H NMR, 13C NMR, and gel permeation chromatography. 1H‐NMR analysis was used to determine the molar fractions of MCTMA and IAOEMA in the copolymers. The monomer‐reactivity ratios were calculated according to the general copolymerization equation using Kelen–Tüdõs and Finemann–Ross linearization methods. The reactivity ratios indicated a tendency toward random copolymerization. The polydispersity indices of the polymers, determined with gel permeation chromatography, suggested a strong tendency for chain termination by disproportionation. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass‐transition temperature of the copolymers increased with increasing MCTMA content in the copolymers. Also, the apparent thermal decomposition activation energies were calculated by the Ozawa method with a Shimadzu TGA 60 thermogravimetric analysis thermobalance. All the products showed moderate activity against different strains of bacteria and fungi. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 530–542, 2008
Development of an immuno tandem mass spectrometry (iMALDI) assay for EGFR diagnosis
Authors: Jiang Jian , Parker Carol E. , Hoadley Katherine A. , Perou Charles M. , Boysen Gunnar , Borchers Christoph H. 
Published: December 2007

AbstractThe epidermal growth factor receptor (EGFR) is highly expressed in a variety of tumors, and is therefore an important biomarker for cancer diagnosis and a target for cancer therapy. We have developed a novel peptide‐based immuno tandem mass spectrometry (iMALDI) diagnostic assay for highly sensitive, highly specific, and quantitative analysis of EGFR, which we have applied to the detection of the EGFR peptide in three cell lines and in a tumor biopsy sample. This assay is capable of detecting the EGFR target peptide bound to the antibody beads at attomole levels. The ability to directly obtain amino acid sequence data by MS/MS on any affinity‐captured peptides provides specificity to this diagnostic technique. This avoids the problem of “false positives” which can result from the nonspecific binding that can occur with any affinity‐based technique. The addition of stable‐labeled versions of the target peptide (synthesized from stable‐isotope coded amino acids) as internal standards allows absolute quantitation of the target protein.
In vitroandin vivoeffects ofRanunculus peltatussubsp.baudotiimethanol extract on models of eicosanoid production and contact dermatitis
Authors: Prieto J. M. , Recio M. C. , Giner R. M. , Schinella G. R. , Máñez S. , Ríos J. L. 
Published: December 2007

AbstractRanunculus(Crowfoot) species are numerous and they are all reputed to be counter‐irritants and are used in several topical conditions. In order to study the pharmacological mechanisms of action underlying this popular use, a methanol extract ofRanunculus peltatuswas testedin vitroin various assays involving eicosanoid and human elastase release by intact cells as well asin vivo, with models of delayed‐type hypersensitivity (DTH) contact dermatitis. The extract proved to be a selective inhibitor of the cyclooxygenase‐1 pathway, producing the total inhibition of 12‐(S)‐HHTrE release at 200 µg/mL, while leaving both 5‐lipoxygenase and 12‐lipoxygenase activities unaffected at the same dose. Then‐hexane, chloroform and ethyl acetate fractions of the crude methanol extract inhibited LTB4release by intact rat peritoneal neutrophils, but more polar fractions were inactive and did not increase the 5‐LOX activity as seen previously for extracts of otherRanunculusspecies. In thein vivomodels, the methanol extract reduced the dinitrofluorobenzene (DNFB)‐induced oedema by 40%, but failed to inhibit the oedema brought on by oxazolone. The results agree with the age‐old assertion that Water Crowfoot species can be used as a topical antiinflammatory remedy without the prominent irritant action that accompanies the application of non‐aquaticRanunculusspecies. Copyright © 2007 John Wiley & Sons, Ltd.
Hypoglycemic activity of Ailanthus excelsa leaves in normal and streptozotocin‐induced diabetic rats
Authors: Cabrera W. , Genta S. , Said A. , Farag A. , Rashed K. , Sánchez S. 
Published: December 2007

AbstractThe hypoglycemic activity of a 70% methanol extract from the leaves of Ailanthus excelsa Roxb. (Simaroubaceae) was studied in normal, transiently hyperglycemic and streptozotocin (STZ)‐induced diabetic rats. Oral administration of the extract at doses of 14, 70 and 350 mg/kg body weight caused no significant changes in fasting blood glucose levels of normal rats. In an oral glucose tolerance test, the extract produced a significant decrease in glycemia 90 min after the glucose pulse. Daily administration of A. excelsa extract for 60 days produced a significant hypoglycemic effect in diabetic animals. In addition, this treatment improved the altered renal function observed in diabetic control rats. This study suggests that Ailanthus leaf extract could be potentially useful for post‐prandial hyperglycemia treatment. Copyright © 2007 John Wiley & Sons, Ltd.
Antiviral and immunomodulatory effect of a lyophilized extract of Capparis spinosa L. buds
Authors: Arena A. , Bisignano G. , Pavone B. , Tomaino A. , Bonina F. P. , Saija A. , Cristani M. , D'Arrigo M. , Trombetta D. 
Published: December 2007

AbstractHerpes simplex virus type 1 (HSV‐1) and herpes simplex virus type 2 (HSV‐2) are common human pathogens that in particular cases can also cause severe problems especially in immunodeficient patients. The present paper reports the antiviral and immunomodulatory properties of a methanolic extract of C. spinosa buds (CAP), rich in flavonoids, including several quercetin and kaempferol glycosides. In particular we have investigated whether the in vitro exposure of human peripheral blood mononuclear cells (PBMCs) to CAP might inhibit the replication of HSV‐2 and modulate the induction kinetics of IL‐12, TNF‐α IFN‐γ. Our findings have shown that CAP treatment interferes with HSV‐2 replication in PBMCs inhibiting the extracellular virus release upregulating their production of IL‐12, IFN‐γ and TNF‐α. One could speculate that CAP may contribute in improving immune surveillance of PBMCs toward virus infection by up‐regulating expression of peculiar proinflammatory cytokines; it should thus be successfully employed for treatment of HSV‐2 infections in immunocompromised hosts.
Simultaneous lipidomic analysis of three families of bioactive lipid mediators leukotrienes, resolvins, protectins and related hydroxy‐fatty acids by liquid chromatography/electrospray ionisation tandem mass spectrometry
Authors: Masoodi Mojgan , Mir Adnan A. , Petasis Nicos A. , Serhan Charles N. , Nicolaou Anna 
Published: December 2007

AbstractBioactive lipid mediators derived from polyunsaturated fatty acids (PUFA) exhibit a range of tissue‐ and cell‐specific activities in many physiological and pathological processes. Electrospray ionisation tandem mass spectrometry coupled to liquid chromatography (LC/ESI‐MS/MS) is a sensitive, versatile analytical methodology for the qualitative and quantitative analysis of lipid mediators. Here we present an LC/ESI‐MS/MS assay for the simultaneous analysis of twenty mono‐ and poly‐hydroxy‐fatty acid derivatives of linoleic, arachidonic, eicosapentaenoic and docosahexaenoic acids. The assay was linear over the concentration range 1–100 pg/µL, whilst the limits of detection and quantitation were 10–20 and 20–50 pg, respectively. The recovery of the extraction methodology varied from 76–122% depending on the metabolite. This system is useful for profiling a range of biochemically related potent mediators including the newly discovered resolvins and protectins, and their precursor hydroxyeicosapentaenoic and hydroxydocosahexaenoic acids, and, consequently, advance our understanding of the role of PUFA in health and disease. Copyright © 2007 John Wiley & Sons, Ltd.
Optimization to eliminate the interference of migration isomers for measuring 1‐O‐β‐acyl glucuronide without extensive chromatographic separation
Authors: Xue Y.‐J. , Akinsanya J. Billy , Raghavan Nirmala , Zhang Donglu 
Published: December 2007

AbstractA highly selected reaction monitoring (SRM) method has been investigated for the determination of muraglitazar 1‐O‐β‐acyl glucuronide in animal and human plasma without chromatographic separation of this naturally formed acyl glucuronide from its migration isomers. In the ion source or the collision cell, glucuronides are often prone to lose the dehydrated glucuronic acid (176 Da) and convert back into the parent drug (aglycone). The extent of loss of the glucuronide moiety can differ among glucuronides. For the naturally occurring muraglitazar 1‐O‐β‐acyl glucuronide, or its synthetic anomer 1‐O‐α‐glucuronide, the loss of the glucuronide moiety was a major fragment ion. The loss of the glucuronide moiety was greater for the 1‐O‐β‐acyl glucuronide than the 1‐O‐α‐anomer. In addition, the loss of the glucuronide moiety was insignificant (less than 0.01%) with the other glucuronide isomers (2‐, 3‐ or 4‐O, α or β). Given the fact that the 1‐O‐α‐anomer was a minor impurity in the muraglitazar 1‐O‐β‐acyl glucuronide reference standard, and not either a conversion product of 1‐O‐β‐acyl glucuronide or endogenously formed, the SRM transition corresponding to the loss of the glucuronide moiety was very specific for 1‐O‐β‐acyl glucuronide, and practically free from interference of the other isomers under optimized collision‐cell conditions. As a result, extensive chromatographic separation of 1‐O‐β‐acyl glucuronide from its migration isomers was not required. The use of this specific SRM transition effectively reduced the separation time from 12.0 min of a long‐column high‐performance liquid chromatography (HPLC) method to 2.5 min by use of a shorter column. The standard curve performance and analysis results of 1‐O‐β‐acyl glucuronide incubation samples showed that the short‐column method could produce equivalent results to the long‐column method but with a 4.5‐fold improvement in sample throughput. This approach may be useful for other 1‐O‐β‐acyl glucuronide measurements with proper tuning of collision energy. The generation of a breakdown curve (abundance vs. collision energy) helps to define whether appropriate conditions may be selected for specific MRM transitions. Copyright © 2007 John Wiley & Sons, Ltd.