bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoinduced Charge Separation in an Aqueous Phase Using Nanoporous TiO2 Film and a Quasi‐Solid Made of Natural Products
Authors: Kaneko Masao , Nomura Tomoyo , Sasaki Chie 
Published: May 2003

AbstractSolar cells comprised of nanoparticulate TiO2 porous film photosensitized with an adsorbing dye have been utilized as photoinduced charge separation systems in aqueous media with the view to forming future artificial photosynthetic systems able to create fuels from solar energy and water. The photoinduced charge separation of the sensitized TiO2 cell in a quasi‐solid, made from agarose or κ‐carrageenan, was investigated.
I–V curves under 98 mW · cm−2 irradiation of ITO/TiO2/Ru(dcbpy)2(NCS)2. Electrolyte: 0.1 M LiI/0.01 M I2 in a quasi‐solid of 0.2 wt.‐% gelatin containing a large excess of water.magnified imageI–V curves under 98 mW · cm−2 irradiation of ITO/TiO2/Ru(dcbpy)2(NCS)2. Electrolyte: 0.1 M LiI/0.01 M I2 in a quasi‐solid of 0.2 wt.‐% gelatin containing a large excess of water.
Temperature‐Sensitive Poly(N‐isopropylacrylamide) Hydrogels with Macroporous Structure and Fast Response Rate
Authors: Zhang Jian‐Tao , Cheng Si‐Xue , Huang Shi‐Wen , Zhuo Ren‐Xi 
Published: May 2003

AbstractMacroporous temperature‐sensitive poly(N‐isopropylacrylamide) (PNIPA) hydrogels were prepared by a novel phase‐separation technique to improve the response properties. In comparison with a conventional PNIPA hydrogel prepared in water, these macroporous hydrogels, prepared by polymerization in aqueous sucrose solutions, have higher swelling ratios at temperatures below the lower critical solution temperature and exhibit much faster response rates to temperature changes.
Scanning electron microscopy image of the surface of a PNIPA hydrogel, prepared in 1.50 M aqueous sucrose solution.magnified imageScanning electron microscopy image of the surface of a PNIPA hydrogel, prepared in 1.50 M aqueous sucrose solution.
Highly Defined ABC Triblock Cooligomers and Copolymers Prepared by ROMP Using an N‐Heterocyclic‐Carbene‐Substituted Ruthenium Benzylidene Initiator
Authors: Slugovc Christian , Riegler Silvia , Hayn Gertraud , Saf Robert , Stelzer Franz 
Published: May 2003

AbstractThe “3rd generation Grubbs” initiator (H2IMes)(3‐bromopyridine)2(Cl)2RuCHPh (1) accomplishes the synthesis of ABC triblock copolymers via living ring‐opening metathesis polymerisation (ROMP) of norbornene derivatives. Complete initiation and an outstanding tolerance of functional groups are provided, which is proven by a combined study by means of matrix‐assisted laser desorption/ionisation mass spectrometry, gel permeation chromatography and NMR spectroscopy on an ABC triblock cooligomer.Gel permeation chromatograms of oligoA, oligoAB, and oligoABC.magnified imageGel permeation chromatograms of oligoA, oligoAB, and oligoABC.
Synthesis of a New Thiophene/Quinoxaline CT‐Type Copolymer with High Solubility and Its Basic Optical Properties
Authors: Yamamoto Takakazu , Lee Ban‐Lin , Kokubo Hisashi , Kishida Hideo , Hirota Keisuke , Wakabayashi Takeru , Okamoto Hiroshi 
Published: May 2003

AbstractA new π‐conjugated charge‐transfer‐type copolymer of electron‐donating thiophene and electron‐accepting quinoxaline was prepared by organometallic polycondensation. The polymer was soluble in organic solvents such as tetrahydrofuran, and showed a UV‐vis peak at long wavelengths of 598 nm in chloroform and 629 nm in the film. Its film exhibited a χ(3) peak in the resonance region with a χ(3) value comparable to that of regioregular head‐to‐tail poly(3‐hexylthiophene‐2,5‐diyl).
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Well‐Controlled Biodegradable Nanocomposite Foams: From Microcellular to Nanocellular
Authors: Fujimoto Youhei , Ray Suprakas Sinha , Okamoto Masami , Ogami Akinobu , Yamada Kazunobu , Ueda Kazue 
Published: May 2003

AbstractVia a batch process in an autoclave, the foam processing of neat polylactide (PLA) and two different types of PLA/layered silicate nanocomposites has been conducted using supercritical carbon dioxide as a foaming agent. The morphological correlation between the dispersed silicate particles with nanometer dimensions in the bulk and the obtained closed‐cell structure of the foam is discussed. This is the first report that deals with the possibility of preparing biodegradable nanocellular polymeric foams via nanocomposite technology.SEM image of the freeze‐fracture surface of a PLA/layered silicate foam, exhibiting closed‐cell structure.magnified imageSEM image of the freeze‐fracture surface of a PLA/layered silicate foam, exhibiting closed‐cell structure.
Spatially Confined Tungstate Ion Polymerization in Microcapsules
Authors: Shchukin Dmitry G. , Dong Wenfei , Sukhorukov Gleb B. 
Published: May 2003

AbstractA new approach for performing the WO42− polymerization reaction exclusively inside polyelectrolyte capsules of a micron scale size is demonstrated. This approach is based upon a pH gradient across the capsule shell (2.5 inside the capsule volume and 6.5 outside the capsule) caused by encapsulated poly(styrene sulfonate) molecules. During the first stage of the reaction, different polytungstate anions were synthesized. Crystalline WO3 nanoparticles were formed inside the capsule as the final polymerization product.The tungstate ion polymerization confined within a micron‐sized polyelectrolyte capsule described herein.magnified imageThe tungstate ion polymerization confined within a micron‐sized polyelectrolyte capsule described herein.
Enzyme‐Catalyzed Preparation of Aliphatic Polyesters Containing Thioester Linkages
Authors: Iwata Shin , Toshima Kazunobu , Matsumura Shuichi 
Published: May 2003

AbstractAliphatic polyesters containing thioester linkages were enzymatically prepared by both the copolymerization of lactone with mercaptoalkanoic acid and by the transesterification of polyesters with mercaptoalkanoic acids. The enzymatic copolymerization of ε‐caprolactone with 11‐mercaptoundecanoic acid (11MU) and 3‐mercaptopropionic acid (3MP) was performed under reduced pressure using an immobilized lipase from Candida antarctica (CA). The transesterification of poly(ε‐caprolactone) and poly[(R)‐3‐hydroxybutyrate] was carried out with 11MU and 3MP using lipase CA under reduced pressure.
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Ethylene and Ethylene/Propylene Polymerization Behavior of Bis(phenoxy‐imine) Zr and Hf Complexes with Perfluorophenyl Substituents
Authors: Ishii Sei‐ichi , Furuyama Rieko , Matsukawa Naoto , Saito Junji , Mitani Makoto , Tanaka Hidetsugu , Fujita Terunori 
Published: May 2003

AbstractThe catalytic properties of bis(phenoxy‐imine) Zr and Hf complexes incorporating perfluorophenyl groups with methylaluminoxane were investigated. The fluorinated complexes produced far higher‐molecular‐weight polyethylenes and ethylene/propylene copolymers with increased activities compared with the non‐fluorinated congeners. Moreover, the fluorinated complexes displayed a higher incorporation ability for propylene.Structures of complexes 1–4.magnified imageStructures of complexes 1–4.
Carbon dioxide laser‐assisted nerve repair: Effect of solder and suture material on nerve regeneration in rat sciatic nerve
Authors: Menovsky Tomas , Beek Johan F. 
Published: May 2003

AbstractIn order to further improve and explore the role of lasers for nerve reconstruction, this study was designed to investigate regeneration of sharply transected peripheral nerves repaired with a CO2 milliwatt laser in combination with three different suture materials and a bovine albumin protein solder as an adjunct to the welding process. Unilateral sciatic nerve repair was performed in 44 rats. In the laser group, nerves were gently apposed, and two stay sutures (10‐0 nylon, 10‐0 polyglycolic acid, or 25‐μm stainless steel) were placed epi/perineurially. Thereafter, the repair site was fused at 100 mW with pulses of 1.0 s. In the subgroup of laser‐assisted nerve repair (LANR), albumen was used as a soldering agent to further reinforce the repair site. The control group consisted of nerves repaired by conventional microsurgical suture repair (CMSR), using 4–6 10‐0 nylon sutures. Evaluation was performed at 1 and 6 weeks after surgery, and included qualitative and semiquantitative light microscopy. LANR performed with a protein solder results in a good early peripheral nerve regeneration, with an optimal alignment of nerve fibers and minimal connective tissue proliferation at the repair site. All three suture materials produced a foreign body reaction; the least severe was with polyglycolic acid sutures. CMSR resulted in more pronounced foreign‐body granulomas at the repair site, with more connective‐tissue proliferation and axonal misalignment. Furthermore, axonal regeneration in the distal nerve segment was better in the laser groups. Based on these results, CO2 laser‐assisted nerve repair with soldering in combination with absorbable sutures has the potential of allowing healing to occur with the least foreign‐body reaction at the repair site. Further experiments using this combination are in progress. © 2003 Wiley‐Liss, Inc. MICROSURGERY 23:109–116 2003
Two‐stage reconstruction of four‐digit amputation: Distal ulnar artery flap and combined second‐ and third‐toe transfer
Authors: Yıldız Mehmet , Şener Muhittin , Turgutoğlu Olcay , Baki Celål 
Published: May 2003

AbstractWe report a case of combined two toe transfer after distal ulnar artery fasciocutaneous flap in a 10‐year‐old boy who has four‐digit amputation. Four years after the operation, satisfactory results were obtained both functionally and cosmetically. © 2003 Wiley‐Liss, Inc. MICROSURGERY 23:103–104 2003
Retrograde arterialized venous flap: An experimental study
Authors: Moshammer Harald E.T. , Schwarzl Franz X. , Haas Franz M. , Maechler Heinrich , Pierer Gerhard , Wiltgen Marco , Koch Horst 
Published: May 2003

AbstractAn experimental model was established to study circulation in retrograde arterialized venous flaps (RAVF). Venous flaps measuring 7 × 4 cm with a matching venous system were harvested from both forearms of 10 fresh human cadavers. In each trial, both flaps were simultaneously perfused with heparinized human blood driven by a pulsatile circulation model. In each trial there was one flap with retrograde perfusion, and one flap with antegrade perfusion. Clinical assessment, measurement of outflow, and angiographic examination with digitally assisted assessment after 3 h of perfusion showed better results for retrograde perfusion in 8 of the 10 trials. This study indicates that blood circulation in the periphery of arterialized venous flaps can be enhanced by retrograde arterialization. © 2003 Wiley‐Liss, Inc. MICROSURGERY 23:130–134 2003
New model for simultaneous heart and kidney transplantation in mice
Authors: Wang Minghui , Bai Jie , Baumann Marcus , Heemann Uwe 
Published: May 2003

AbstractIn clinical settings, combined heart and kidney transplantation results in a lower incidence of cardiac graft and renal graft rejection as compared to isolated heart and kidney transplantation. To study the phenomenon in an experimental setting, we developed a model of combined heart and kidney transplantation in mice. According to our technique, we kept the patch of the infrarenal aorta and inferior vena cava (IVC) as long as possible during the donor's kidney explantation, and then, after finishing the kidney implantation with conventional techniques, we anastomosed the innominate artery and pulmonary artery of the heart graft to the patch of the infrarenal aorta and IVC of the renal graft, respectively, instead of the recipient's aorta and IVC. With the use of our method, combined heart and kidney transplantation in mice can be performed to get enough suture room for the second graft, to avoid prolonging the occlusion time of the recipient's circulation, and to profoundly decrease postoperative complications such as paraplegia and mortality. Of the 14 recipients with combined heart‐kidney isografting, 10 have been successful (71.4%), surviving over 100 days with normal function of both grafts, and with lack of change in histological appearance. This suggests that the technique is feasible and reliable. © 2003 Wiley‐Liss, Inc. MICROSURGERY 23:164–168 2003
NMR analysis of biindenylidenes
Authors: Spiteller Peter , Jovanovic Jovan , Spiteller Michael 
Published: May 2003

AbstractThe 1H and 13C NMR parameters (chemical shifts and coupling constants) were determined of four biindenylidene isomers, (E)‐2,3,2′,3′‐tetrahydro‐[1,1′]biindenylidene, (Z)‐2,3,2′,3′‐tetrahydro‐[1,1′]biindenylidene, 1,3,1′, 3′‐tetrahydro‐[2,2′]biindenylidene and 2,3,1′,3′‐tetrahydro‐[1,2′]biindenylidene. Copyright © 2003 John Wiley & Sons, Ltd.
Electronic structure of thiazides studied by 35Cl‐NQR spectroscopy and DFT calculations
Authors: Latosińska J. N. 
Published: May 2003

AbstractNQR frequencies were determined for the 35Cl isotope in a few benzodithiazine derivatives, chlorothiazide (CTZ), hydrochlorothiazide (HCTZ), althiazide (ATZ), trichloromethiazide (TCTZ), benzthiazide (BTZ) and furosemide (FSE), at liquid nitrogen and room temperatures. It was found that changes of the substituent at C‐3 are transferred through a system of coupled rings on to the chlorine atom at C‐6. The substituents occurring in thiazides can be ordered according to increasing electron‐acceptor properties as —CH2SCH2Ph < —CH2SCH2CHCH2 <—CHCl2. At the liquid nitrogen temperature —CH2SCH2Ph and —CH2SCH2CHCH2 are electron donors, and CHCl2 is an electron acceptor, whereas at room temperature —CH2SCH2Ph is an electron donor and —CH2SCH2CHCH2 and —CHCl2 are electron acceptors. The character of the substituent properties is preserved irrespective of whether the system is aromatic or aliphatic. The NQR frequencies and substituents properties are well reproduced by the DFT B3LYP/6–311+G(2d,p) method. The topological properties of the Laplacian of the electron density were analysed within the AIM (atoms in molecules) approach. The changes in the electron density at C‐3 are correlated with the biological activity of the compounds studied. Copyright © 2003 John Wiley & Sons, Ltd.
31P CP/MAS NMR of polycrystalline and immobilized phosphines and catalysts with fast sample spinning
Authors: Reinhard S. , Blümel J. 
Published: May 2003

AbstractCross‐polarization (CP) at fast magic angle spinning (MAS) frequencies leads to a splitting of the Hartmann–Hahn (HH) matching profile into a centerband and additional bands of higher orders. The matching profiles differ with the substance categories. Therefore, signal intensity is usually lost, when e.g. the routine standard NH4H2PO4 is used for optimizing the 1H–31P HH match prior to measuring phosphines and their metal complexes in polycrystalline or immobilized form. Here, a variety of model compounds, such as Ph2PCH2CH2PPh2 and (CO)2Ni(PPh3)2, which can be used as 31P CP standards for analogous substances or materials are presented. Investigating the influences of MAS frequency, contact time, 1H pulse power and sample volume on the matching profiles of the model compounds leads to general trends. Thereby, a new strategy for measuring difficult samples with CP at high MAS rates has been developed: their optimum CP parameters are derived from the most intense maxima in the HH matching profiles of the corresponding model compounds. This new strategy is compared with variations of a conventional ramp sequence. Although the latter generally provide smaller signal half‐widths, the new strategy leads to higher signal intensities. The new method was successfully applied to polycrystalline and immobilized phosphines and catalysts. Copyright © 2003 John Wiley & Sons, Ltd.
A selective pulse sequence for the determination of long‐range C,H spin coupling constants
Authors: Findeisen M. , Berger S. 
Published: May 2003

AbstractA new pulse sequence for determining scalar long range C,H spin couplings in small organic molecules is proposed. It is based on the combination of a selective J‐resolved spectrum with a selective HMBC and displays the long‐range spin couplings of one chosen carbon atom in the indirect dimension. Advantages and disadvantages are discussed on example spectra of ethanol, strychnine and sucrose. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis and spectral study of a novel distamycin conjugate
Authors: Pineda de las Infantas M. J. , Campos J. , Baraldi P. G. , Romagnoli R. , Gallo M. A. , Espinosa A. 
Published: May 2003

AbstractThe 1H and 13C NMR resonances for a novel distamycin conjugate, 3‐[1‐methyl‐4‐[1‐methyl‐4‐[1‐methyl‐4‐[N1‐[5‐methyl‐2,4(1H,3H)pyrimidinedione]acetylamino]pyrrole‐2‐carboxamido]pyrrole‐2‐carboxamido]pyrrole‐2‐carboxamido]propionamidine hydrochloride (1), were assigned, using the concerted application of one‐ and two‐dimensional NMR techniques including nuclear Overhauser effect difference, DEPT, HMQC and HMBC experiments. Copyright © 2003 John Wiley & Sons, Ltd.
Solid‐state cross‐polarization magic angle spinning 13C and 15N NMR characterization of Sepia melanin, Sepia melanin free acid and Human hair melanin in comparison with several model compounds
Authors: Adhyaru Bhavin B. , Akhmedov Novruz G. , Katritzky Alan R. , Bowers Clifford R. 
Published: May 2003

AbstractThis paper presents the high‐resolution 13C and 15N cross‐polarization magic angle spinning (CP/MAS) NMR spectra of three natural melanin solids: Sepia officinalis melanin, Sepia officinalis melanin free acid (MFA) and Human hair melanin. The functional group characterization of Human hair melanin by NMR is the first to date and the 13C CP/MAS NMR spectra reported here show improved resolution of chemically inequivalent sites. The observed spectral regions of the solid melanin samples can be assigned to the postulated structural unit of the polymer chain of Sepia MFA derived from solution‐state NMR studies. To assist in the assignment of functional groups in the spectra, the solid‐state CP/MAS NMR spectra are compared with high‐resolution 13C and 15N CP/MAS spectra of four model compounds, L‐dopa, dopamine, 2‐methoxycarbonyl‐3‐ethoxycarbonyl‐4‐methylpyrrole and ethyl 5,6‐dimethoxyindole‐2‐carboxylate. To aid further in the assignment of protonated and non‐protonated carbon atoms, CP contact time dependence and non‐quaternary carbon suppression (NQS) experiments were performed on the melanin samples. The 15N CP/MAS spectra of the melanin samples confirm the presence of indole and pyrrole units in the melanin polymer chain. The NMR peaks observed in all of the melanin samples are relatively broad, presumably owing to the presence of free radicals. Electron spin resonance (ESR) data shows that all three melanin samples contain localized free radicals (g = 2.007), with the Sepia melanin containing a 10‐fold higher free radical density than Human hair melanin. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis and 1H and 13C NMR structural analysis of cis‐ and trans‐2‐imino‐1,3‐ and ‐3,1‐perhydrobenzoxazines and their 3‐ and 1‐N‐methyl derivatives
Authors: Pihlaja Kalevi , Sinkkonen Jari , Fülöp Ferenc 
Published: May 2003

Abstractcis‐ and trans‐2‐imino‐1,3‐ and ‐3,1‐perhydrobenzoxazines and the N‐methyl derivatives of the latter were synthesized from the corresponding cyclic 1,3‐amino alcohol with cyanogen bromide. The configurations of the studied compounds were confirmed by 1H and 13C NMR spectra. All trans‐fused compounds exist in biased chair–chair conformations as expected, whereas the cis‐fused 1,3‐benzoxazines attain exclusively the O‐in conformations. The cis‐fused 3,1‐benzoxazines, especially the 1‐methyl‐substituted derivatives, tend to favor the N‐out form, obviously owing to the favorable axial orientation of this N‐methyl. Copyright © 2003 John Wiley & Sons, Ltd.
A fast method for the measurement of diffusion coefficients: one‐dimensional DOSY
Authors: Thrippleton Michael J. , Loening Nikolaus M. , Keeler James 
Published: May 2003

AbstractA new experiment for the single‐scan measurement of diffusion coefficients is presented. The principle is to introduce a spatial variation in the parameters of a conventional pulse sequence, so that all of the scans required to determine some physical parameter can be recorded simultaneously from different parts of the sample. The spectrum is acquired in the presence of a weak read gradient so that the resulting lineshapes contain the information required. The pulse sequence is described in detail and demonstrated on a sample containing three components; its advantages and limitations are discussed in relation to those of existing techniques. For uncrowded spectra with high signal‐to‐noise ratio, this experiment provides an order of magnitude reduction in experiment time compared with conventional methods and is likely to be of most benefit where samples are changing rapidly with time or where a long period of polarization, which may be difficult to reproduce accurately, prohibits the use of multiple‐scan techniques. Copyright © 2003 John Wiley & Sons, Ltd.
Critical investigation of coupled liquid chromatography–NMR spectroscopy in pharmaceutical impurity identification
Authors: Sharman Gary J. , Jones Ian C. 
Published: May 2003

AbstractIn this paper, we investigate the application of coupled LC–NMR to the identification of low‐level impurities. We consider the absolute sensitivity of the technique with our instrumentation, and how this is degraded by peak broadening on and after column, and we compare the sensitivity and other aspects of LC–NMR with a more classical approach of impurity isolation and tube NMR. We show that despite the undoubted advantages of LC–NMR in many situations, for the identification of very low‐level impurities it may not always be the most efficient overall approach when all factors are considered. Copyright © 2003 John Wiley & Sons, Ltd.
Phenylselenenylalkanes, their adducts with the dirhodium complex Rh2(MTPA)4 and ligand exchange mechanisms in solution as studied by 1H, 13C and 77Se NMR spectroscopy
Authors: Malik Shahid , Moeller Stefan , Tóth Gábor , Gáti Tamás , Choudhary Muhammad Iqbal , Duddeck Helmut 
Published: May 2003

AbstractTwelve secondary phenylselenenylalkanes and ‐cycloalkanes were studied by 1H, 13C and 77Se NMR spectroscopy in the presence of the chiral dirhodium complex Rh2[(R)‐MTPA]4 [Rh–Rh; MTPA‐H = (R)‐(+)‐methoxytrifluoromethylphenylacetic acid, Mosher's acid]. The 1 : 1 and 2 : 1 adducts were identified in solution at low temperatures. Two different mechanisms of ligand exchange, ‘switch’ and ‘replacement,’ were characterized and their energy barriers estimated and steric congestion during the exchange transitions is discussed. Coordination‐induced shifts Δδ(77Se) are generally negative (shielding). For menthone bis(phenylselenoacetal) (7), these values indicate that a selection of the two selenium atoms occurs showing that 7 prefers complexation at the equatorial selenium atom whereas the axial selenium atom is hardly involved. Copyright © 2003 John Wiley & Sons, Ltd.