bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, characterization, and properties of intercalated poly(2‐ethyl hexylacrylate)/silicate nanocomposites: XRD, TEM, IR, TGA, superabsorbency, pressure‐sensitive adhesion, and biodegradation
Authors: Rana Pradeep Kumar , Swain Sarat Kumar , Sahoo Prafulla Kumar 
Published: April 2004

AbstractPoly(2‐ethyl hexylacrylate) (PEHA)/silicate composites were synthesized by the emulsion polymerization of ethyl hexylacrylate (EHA) in the presence of sorbitol and the composites were analyzed to be of nano order. The nanocomposites so prepared were shown to be intercalated by X‐ray diffraction, transmission electron microscopy, and infrared spectroscopy. The thermal stability of the nanocomposites was found to be appreciably increased. These nanocomposites are potentially suitable for novel uses such as pressure‐sensitive adhesives and superabsorbents. The biodegradability and superabsorbency of these nanocomposites were evaluated for their commercial potential. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1007–1011, 2004
Multizone circulating reactor modeling for gas‐phase polymerization. II. Reactor operating with gas barrier in the downer section
Authors: Fernandes Fabiano A. N. , Lona Liliane M. F. 
Published: April 2004

AbstractA new gas‐phase technology for polyolefin production is being developed to be commercially available for large‐scale production between 2004 and 2005. This new technology uses a multizone circulating reactor, which consists of two interrelated zones where two distinct and different fluodynamic regimes are realized, between which the polymer particles are kept in continuous circulation. In the first part, we presented a mathematical model for the reactor, and this second part of the article we present simulations when a gas barrier is introduced in the top of the downer section and its implications in the polymer characteristics. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1053–1059, 2004
Multizone circulating reactor modeling for gas‐phase polymerization. I. Reactor modeling
Authors: Fernandes Fabiano A. N. , Lona Liliane M. F. 
Published: April 2004

AbstractA new gas‐phase technology for polyolefin production is being developed to be commercially available for large‐scale production between 2004 and 2005. This new technology uses a multilane circulating reactor, which consists of two interrelated zones where two distinct and different fluodynamic regimes are realized, between which the polymer particles are kept in continuous circulation. This article presents a mathematical model for the multilane circulating reactor presenting the typical behavior of the reactor operation and a parameter sensibility analysis. Simulations were conducted for polyethylene production. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1042–1052, 2004
Fluorine in Medicinal Chemistry
Authors: Böhm Hans‐Joachim , Banner David , Bendels Stefanie , Kansy Manfred , Kuhn Bernd , Müller Klaus , Obst‐Sander Ulrike , Stahl Martin 
Published: April 2004

AbstractFluorinated compounds are synthesized in pharmaceutical research on a routine basis and many marketed compounds contain fluorine. The present review summarizes some of the most frequently employed strategies for using fluorine substituents in medicinal chemistry. Quite often, fluorine is introduced to improve the metabolic stability by blocking metabolically labile sites. However, fluorine can also be used to modulate the physicochemical properties, such as lipophilicity or basicity. It may exert a substantial effect on the conformation of a molecule. Increasingly, fluorine is used to enhance the binding affinity to the target protein. Recent 3D‐structure determinations of protein complexes with bound fluorinated ligands have led to an improved understanding of the nonbonding protein–ligand interactions that involve fluorine.
Zinc(II)‐Selective Ratiometric Fluorescent Sensors Based on Inhibition of Excited‐State Intramolecular Proton Transfer
Authors: Henary Maged M. , Wu Yonggang , Fahrni Christoph J. 
Published: April 2004

AbstractTo develop a zinc(II)‐selective emission ratiometric probe suitable for biological applications, we explored the cation‐induced inhibition of excited‐state intramolecular proton transfer (ESIPT) with a series of 2‐(2′‐benzenesulfonamidophenyl)benzimidazole derivatives. In the absence of ZnII at neutral pH, the fluorophores undergo ESIPT to yield a highly Stokes' shifted emission from the proton‐transfer tautomer. Coordination of ZnII inhibits the ESIPT process and yields a significant hypsochromic shift of the fluorescence emission maximum. Whereas the paramagnetic metal cations CuII, FeII, NiII, CoII, and MnII result in fluorescence quenching, the emission response is not altered by millimolar concentrations of CaII or MgII, rendering the sensors selective for ZnII among all biologically important metal cations. Due to the modular architecture of the fluorophore, the ZnII binding affinity can be readily tuned by implementing simple structural modifications. The synthesized probes are suitable to gauge free ZnII concentrations in the micromolar to picomolar range under physiological conditions.
Charge Density and Experimental Electrostatic Potentials of Two Penicillin Derivatives
Authors: Wagner Armin , Flaig Ralf , Dittrich Birger , Schmidt Horst , Koritsánszky Tibor , Luger Peter 
Published: April 2004

AbstractTwo penicillin derivatives, the active penamecillin and the inactive penamecillin‐1β‐sulfoxide, were used to study the relationship between their charge density and their activity. Single crystals of both compounds were measured at the synchrotron beamline F1 at the HASYLAB/DESY, at 100 K and up to resolutions of around 0.4 Å. Experimental charge densities were obtained by using the Hansen–Coppens multipole formalism. The cleavage of the amide bond in the β‐lactam ring is of paramount importance in the mechanism of action of penicillins. Topological analysis of this bond in terms of Bader's AIM theory showed that its strength is equal in both compounds; therefore a direct influence of bond strength on the activity can be ruled out. However, the two derivatives differ significantly in their experimental electrostatic potentials. These differences are discussed and provide further insight into the chemistry and activity of penicillins.
New Ligands for a General Palladium‐Catalyzed Amination of Aryl and Heteroaryl Chlorides
Authors: Rataboul Franck , Zapf Alexander , Jackstell Ralf , Harkal Surendra , Riermeier Thomas , Monsees Axel , Dingerdissen Uwe , Beller Matthias 
Published: April 2004

AbstractThe synthesis and application of monodentate N‐substituted heteroarylphosphines is described. In general, the ligands are conveniently prepared by selective metallation at the 2‐position of the respective N‐substituted heterocycle (pyrrole, indole) by using n‐butyllithium/tetramethylethylenediamine (TMEDA) followed by quenching with dialkyl‐ or diarylchlorophosphines. Of the different ligands prepared, the new dialkyl‐2‐(N‐arylindolyl)phosphines (cataCXium® P) perform excellently in the palladium‐catalyzed amination of aryl and heteroaryl chlorides. Coupling of both activated and deactivated chloroarenes proceeds under mild conditions (room temperature to 60 °C). By using optimized conditions remarkable catalyst productivity (total turnover number, TON, up to 8000) and activity (turnover frequency, TOF=14 000 h−1 at 75 % conversion) are observed.
Organische Synthese mit mikrostrukturierten Reaktoren
Authors: Hessel V. , Löwe H. 
Published: April 2004

AbstractDieser Artikel beschreibt zunächst, welche Chancen mikrostrukturierte Reaktoren für den chemischen Anlagenbau haben. Die Eignung für die chemische Produktion wird als Schlüssel zum Markteintritt gesehen. Jahrhunderte langes Beharren auf konventioneller Rührtechnik und kapitalintensive Großanlagen verwehren einen schnellen Eintritt; langfristig können Neuanlagen aber mit mikrostrukturierten Reaktoren versehen werden. Erst Gesamtprozessbetrachtungen, die eine positive wirtschaftliche Bilanz ziehen, werden der chemischen Mikroprozesstechnik die Tür zum Anlagenbau öffnen. Wesentlich Argumente für mikrostrukturierte Reaktoren sind erhöhte Umsatz und Selektivität, erhöhte Raum‐Zeit‐Ausbeute, geringerer Abfall und erhöhte Sicherheit durch kleine Reaktorvolumina. Auf chipkartengroßen Reaktionssystemen lassen sich für das Screening Mehrstufensynthesen in einem Ablauf durchführen. Ebenso wird für das Screening von Einstufenreaktionen Information schneller und zuverlässiger zugänglich. Auch das sichere Arbeiten im Ex‐Bereich erweitert das klassische Prozessspektrum. Reaktionsführungen im Mikrostrukturreaktor beeinflussen auch nachfolgende Prozessschritte wie die Reinigung des Produkts und erniedrigen so z. B. die Energiekosten des Prozesses.
Mischen und organische Reaktionen in der chemischen Industrie
Authors: Bayer T. , Himmler K. 
Published: April 2004

AbstractMischvorgänge sind eine der wichtigsten Grundoperationen in der chemischen Industrie. Neben normalen Rührkesseln werden oft auch statische Mischer verwendet. Seit einigen Jahren erfreut sich aber auch die Mikrotechnik einer wachsenden Aufmerksamkeit in der Prozessentwicklung. Sie wird – insbesondere in der chemischen Verfahrenstechnik – zu einem wertvollen Werkzeug für Forschung und Entwicklung. Dabei wird die Mikroreaktionstechnik sowohl für die Entwicklung neuer Prozesse als auch bei der Optimierung existierender Verfahren angewandt. Mikrostrukturierte Mischer und Wärmeübertrager werden eingesetzt, um das Potenzial von chemischen Reaktionen – ohne Wärme‐ oder Stofftransportlimitierungen – zu untersuchen und zu optimieren. Auch erste Anwendungen über den Labormaßstab hinaus sind bekannt.
Carbon‐protonation of the pyrimidine ring: The story of a small molecule NMR problem
Authors: Demeter Ádám , Wéber Csaba 
Published: April 2004

AbstractThis article provides a case study of a small molecule structure determination problem from the perspective of the true experience of the authors. By starting from what was intended to be a routine acylation of an aminopyrimidine derivative, we arrive, via some intriguing detours, at an unexpected carbon‐protonated pyrimidine dimer. A didactic discussion is provided, which serves to highlight the way in which some puzzling questions cropped up during nuclear magnetic resonance (NMR) spectral interpretation, as well as the iterative process in which these problems were resolved gradually. Some of the crucial mental leaps that either slowed down or gave a thrust to the progress of structure elucidation are emphasized so as to be instructive in ways that go beyond the specifics of the problem. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson 22A: 12–24, 2004.
Combination of endometrial thickness and time since menopause in predicting endometrial cancer in women with postmenopausal bleeding
Authors: Bruchim Ilan , Biron‐Shental Tal , Altaras Marco M. , Fishman Ami , Beyth Yoram , Tepper Ronnie , Aviram Rami 
Published: April 2004

AbstractPurposeThis study was conducted to assess the combination of endometrial thickness, as measured by transvaginal sonography, and time since menopause, in predicting the presence of endometrial cancer in women with postmenopausal bleeding.MethodsThe study group consisted of 95 women with postmenopausal bleeding who underwent sonographic measurement of endometrial thickness followed by endometrial biopsy. No patient had ever received hormone replacement therapy.ResultsThe mean endometrial thickness was significantly lower in the absence of endometrial carcinoma (6.9 ± 4.3 mm) than in its presence (13.5 ± 7.7 mm) (p < 0.005). The incidence of endometrial carcinoma increased with increases in endometrial thickness and the number of years since menopause. No patient had carcinoma when the endometrium was less than 5 mm thick, but 18.5% did when the thickness exceeded 9 mm. The incidence of cancer was 2.6% in women who had undergone menopause less than 5 years earlier but was 21.4% in women who had undergone menopause more than 15 years prior. Multiple logistic regression analysis showed that time since menopause and endometrial thickness were statistically significant predictors of endometrial carcinoma.ConclusionsTime since menopause and endometrial thickness together define cutoff points for the diagnostic biopsy of tissue samples for endometrial carcinoma; that is, within a particular time interval, samspling should not be performed if the thickness is below a given value. When using cutoff points of 6 mm of endometrial thickness for women experiencing menopause 5–15 years prior and 5 mm in those going through menopause 15 or more years prior, approximately 60% of invasive procedures may be avoided. In addition, models derived by multiple logistic regression can be used to calculate a patient's risk of cancer based on her age and endometrial thickness. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:219–224, 2004; Published online in Wiley InterScience (www.interscience.wiley. com). DOI: 10.1002/jcu.20020
Placental thickness in the first half of pregnancy
Authors: Tongsong Theera , Boonyanurak Pongrak 
Published: April 2004

AbstractPurposeThis study was conducted to establish normal values of placental thickness during the first half of pregnancy.MethodsNormal pregnant women with singleton pregnancies between 8 and 20 weeks of gestation were recruited into the study. All the newborns were normal at birth. Placental thickness was measured perpendicularly through the thickest part of the placenta on transabdominal scans. The placental thickness data were analyzed for mean, standard deviation, 95% confidence interval, and 2.5th, 5th, 50th, 95th, and 97.5th percentile for each week of gestational age. The best‐fit mathematical model was derived by regression analysis.ResultsThe total number of measurements was 333 and the number of measurements for each week of gestational age ranged from 9 to 37. Regression analysis yielded the following linear equation of the relationship: placental thickness (in mm) = gestational age (in weeks) × 1.4−5.6 (r = 0.82).ConclusionWe have established a nomogram for placental thickness. This resource may be a useful aid in the early detection of placental abnormalities, such as hydropic placenta secondary to hemoglobin Bart's disease. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:231–234, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.20023
Gene transfer into rabbit arteries with adeno‐associated virus and adenovirus vectors
Authors: Gruchała Marcin , Bhardwaj Shalini , Pajusola Katri , Roy Himadri , Rissanen Tuomas T. , Kokina Ilze , Kholová Ivana , Markkanen Johanna E. , Rutanen Juha , Heikura Tommi , Alitalo Kari , Büeler Hansruedi , Ylä‐Herttuala Seppo 
Published: April 2004

AbstractBackgroundGene transfer offers considerable potential for altering vessel wall physiology and intervention in vascular disease. Therefore, there is great interest in developing optimal strategies and vectors for efficient, targeted gene delivery into a vessel wall.MethodsWe studied adeno‐associated viruses (AAV; 9 × 108 to 4 × 109 TU/ml) for their usefulness to transduce rabbit arteries in vivo in comparison with adenoviruses (Adv; 1 × 109 to 1 × 1010 pfu/ml). 100 µl of viruses or placebo solution were injected intraluminally into transiently isolated carotid segments.ResultsIn normal arteries AAV transduced mainly medial smooth muscle cells (SMC) while Adv transduced exclusively endothelial cells (EC). Mechanical injury to EC layer and internal elastic lamina enabled Adv to penetrate and transduce medial SMC. Transgene expression in EC after the AAV‐mediated gene transfer was very low. The use of the EC‐specific Tie‐1 promoter did not lead to specific transgene expression in EC. Transgene expression in SMC persisted for at least 100 days after the AAV treatment whereas the Adv‐mediated effect diminished in 14 days. AAV caused only a modest increase in EC VCAM‐1 expression and proliferation rate of vascular cells as compared with the mock‐treated arteries while Adv caused an extensive inflammatory cell infiltration, VCAM‐1 expression, vascular cell proliferation and morphological damages.ConclusionsSignificant differences were observed between the AAV and the Adv vectors in their patterns of arterial transduction and consequent inflammatory responses. These distinct properties may be utilized for different applications in vascular biology research and gene therapy for cardiovascular diseases. Copyright © 2004 John Wiley & Sons, Ltd.
Hydrodynamics‐based procedure involves transient hyperpermeability in the hepatic cellular membrane: implication of a nonspecific process in efficient intracellular gene delivery
Authors: Kobayashi Naoki , Nishikawa Makiya , Hirata Kazuhiro , Takakura Yoshinobu 
Published: April 2004

AbstractBackgroundThe mechanisms underlying the efficient gene transfer by a large‐volume and high‐speed intravenous injection of naked plasmid DNA (pDNA), a so‐called hydrodynamics‐based procedure, remain unclear and require further investigation. In this report, we have investigated possible mechanisms for the intracellular transport of naked pDNA by this procedure.MethodsPropidium iodide (PI), a fluorescent indicator for cell membrane integrity, and luciferase‐ or green fluorescent protein (GFP)‐expressing pDNA were injected into mice by the hydrodynamics‐based procedure.ResultsPI was efficiently taken up by hepatocytes which appeared to be viable following the hydrodynamics‐based procedure. Pre‐expressed GFP in the cytosol was rapidly eliminated from the hepatocytes by a large‐volume injection of saline. The profiles of plasma ALT and AST showed a steady decline with the highest values observed immediately after the hydrodynamics‐based procedure. These results suggest that the hydrodynamics‐based procedure produces a transient increase in the permeability of the cell membrane. The cellular uptake process appeared nonspecific, since simultaneous injection of an excess of empty vector did not affect the transgene expression. Sequential injections of a large volume of pDNA‐free saline followed by naked pDNA in a normal volume revealed that the increase in membrane permeability was transient, with a return to normal conditions within 30 min. Transgene expression was observed in hepatocyte cultures isolated 10 min after pDNA delivery and in the liver as early as 10 min after luciferase‐expressing RNA delivery, indicating that pDNA delivered immediately by the hydrodynamics‐based procedure has the potential to produce successful transgene expression.ConclusionsThese findings suggest that the mechanism for the hydrodynamics‐based gene transfer would involve in part the direct cytosolic delivery of pDNA through the cell membrane due to transiently increased permeability. Copyright © 2004 John Wiley & Sons, Ltd.
Spanningk‐arc‐strong subdigraphs with few arcs ink‐arc‐strong tournaments
Authors: Bang‐Jensen Jørgen , Huang Jing , Yeo Anders 
Published: April 2004

AbstractGiven ak‐arc‐strong tournamentT, we estimate the minimum number of arcs possible in ak‐arc‐strong spanning subdigraph ofT. We give a construction which shows that for eachk≥ 2, there are tournamentsTonnvertices such that everyk‐arc‐strong spanning subdigraph ofTcontains at least$nk + {k(k-1)\over 2}$arcs. In fact, the tournaments in our construction have the property that every spanning subdigraph with minimum in‐ and out‐degree at leastkhas$nk + {k(k-1)\over 2}$arcs. This is best possible since it can be shown that everyk‐arc‐strong tournament contains a spanning subdigraph with minimum in‐ and out‐degree at leastkand no more than$nk + {k(k-1)\over 2}$arcs. As our main result we prove that everyk‐arc‐strong tournament contains a spanningk‐arc‐strong subdigraph with no more than$nk + 136k^2$arcs. We conjecture that for everyk‐arc‐strong tournamentT, the minimum number of arcs in ak‐arc‐strong spanning subdigraph ofTis equal to the minimum number of arcs in a spanning subdigraph ofTwith the property that every vertex has in‐ and out‐degree at leastk. We also discuss the implications of our results on related problems and conjectures. © 2004 Wiley Periodicals, Inc. J Graph Theory 46: 265–284, 2004
T‐complete functions for thin and thick plates on elastic foundation
Authors: Wróblewski Adam 
Published: April 2004

AbstractThis article deals with Trefftz functional systems for thin and thick plates on one‐ and two‐parameter Winkler foundation. The T‐complete set is derived by solving the homogeneous equations of the problem. This can be done with the method of separation of variables. For each separation parameter we deal with ordinary, linear differential equations (4th order for the Kirchhoff plate and set of fourth‐ and second‐order equations for the Reissner‐Mindlin plate) so the demanded number of fundamental solutions (linearly independent) is equal to the order of equation. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
Improvement of the interfacial compatibility between sugar cane bagasse fibers and polystyrene for composites
Authors: García‐Hernández Edgar , Licea‐Claveríe Angel , Zizumbo Arturo , Alvarez‐Castillo Alberto , Herrera‐Franco Pedro J. 
Published: April 2004

AbstractSugar cane bagasse fibers were modified by surface treatments using either physical or chemical methods in order to improve their adhesion to polystyrene matrices. The surface treatment methods used were alkaline treatment, treatment with silane coupling agents, physical coating with polystyrene and grafting of polystyrene with and without crosslinker. Fiber modifications were monitored by Fourier Transform Infrared Spectroscopy (FTIR), Differential Thermal Analysis coupled with Thermogravimetric Analysis (DTA‐TGA) and Scanning Electron Microscopy (SEM). On the other hand, the improvement of the adhesion between sugar cane modified fibers and polystyrene was assessed by micromechanical pull‐out and by macromechanical Iosipescu tests. It was found, from Interfacial Shear Strength values (IFSS), that substantial improvements in fiber‐matrix compatibility were achieved. According to micro‐ and macromechanical test results, the IFSS increased for all treated fibers as compared to non‐treated fibers. Particularly, both the coating the fibers or grafting with polystyrene using crosslinker resulted in substantial adhesion improvement to the polystyrene matrix in comparison with the non‐treated fibers and fibers treated by alkaline and silane methods only. Polym. Compos. 25:134–145, 2004. © 2004 Society of Plastics Engineers.
Quality of life of patients with cancer in India: Challenges and hurdles in putting theory into practice
Authors: Pandey Manoj 
Published: April 2004

AbstractAlthough well establish in west, quality of life is a relatively new concept in India. The success of treatment is still measured in term of number of years and not as number of quality years. We carried out a systematic review of the reports published from India on quality of life in cancer patients. Majority of the studies originated from the southern part of India, this was not surprising as this part has literacy rates and health indices at par with developed countries. The studies mainly dealt with translation of existing tools in local vernacular, development of new tools, cross‐sectional studies, and studies on palliative care. This article reviews these studies and presents the results of what has been done so far and goes on to stipulate what more needs to be done. Copyright © 2004 John Wiley & Sons, Ltd.
Approximate Method for Predicting Chapman‐Jouguet State for Condensed Explosives
Authors: Nagayama Kunihito , Kubota Shiro 
Published: April 2004

AbstractThe dependence of the detonation velocity on the initial density is available for several condensed high explosives. It gives a collection of Rayleigh lines on a pressure‐volume plane starting from different initial volume points. It is shown that a collection of the Chapman‐Jouguet (C‐J) states on each Rayleigh line can be described by an envelope function of Rayleigh lines. Based on the analytical expression of the envelope function, formulae for other C‐J parameters are derived.