bluuebunny/crossref_metadata_2025_split huggingface dataset:
Einwirkung von Bitumen auf Kunststoff‐Dach‐ und ‐Dichtungsbahnen
Authors: Glück Leopold 
Published: May 2004

AbstractDie Bitumenverträglichkeit wird zukünftig nach der europäischen Norm DIN EN 1548 geprüft und nach DIN EN 13956 bewertet werden. Die Ergebnisse belegen, daß die in der derzeitigen Fassung der vorstehenden Normen vorgesehenen Verfahren und Bewertungen nur unzureichend geeignet sind, eine zuverlässige Beurteilung und Einstufung der Bahnen in bitumenverträglich oder nicht bitumenverträglich vorzunehmen. Auch einige aktuelle Einstufungen von Herstellern müssen als kritisch angesehen werden.
Einfluß der Deckenschlankheit auf den Durchstanzwiderstand nach DIN 1045‐1, SIA 262, Ö‐Norm B 4700(01) und Eurocode prEN 1992‐1‐1
Authors: Hegger Josef , Beutel Rüdiger , Kerkeni Naceur 
Published: May 2004

AbstractDie oben angeführten Normen [1] — [4] zeigen deutliche Bemessungsunterschiede im Bereich des Durchstanzens mit und ohne Durchstanzbewehrung: (a) Flachdecken geringer Schlankheit (λ = Stützweite / statische Nutzhöhe l/d = 20) weisen nach Ö‐Norm B 4700(01) und SIA 262 einen höheren Durchstanzwiderstand auf als schlanke Flachdecken (l = l/d = 35). Nach DIN 1045‐1 und prEN 1992‐1‐1 bleibt dieser günstige Systemeinfluß unberücksichtigt. (b) Nach prEN 1992‐1‐1 übersteigt der maximale Durchstanzwiderstand für Bügel die Durchstanztragfähigkeit von Doppelkopfankern, was den Erfahrungen aus Versuchen widerspricht [5]. Im Beitrag werden die Bemessungsunterschiede bewertet, der Einfluß einer Gewölbetragwirkung in Abhängigkeit von der Deckenschlankheit diskutiert und baupraktische Empfehlungen zur Durchstanzbemessung gegeben.
Kellerwände aus unbewehrtem Beton
Authors: Hegger Josef , Will Norbert , Niewels Jörg 
Published: May 2004

AbstractAusgehend von DIN 1045‐1 und DIN 1045 werden unter Berücksichtigung der Verformungsfähigkeit Bemessungsnomogramme für unbewehrte Betonwände im Kellerbereich vorgestellt, deren Hauptanwendungsgebiet im Wohnungsbau liegt. Durch Ausnutzung der Verformungsfähigkeit kann die rechnerische Traglast für durch Erddruck beanspruchte unbewehrte Kelleraußenwände gegenüber einer bisher üblichen Bemessung deutlich gesteigert werden. Im Auftrag der Forschungsgemeinschaft Transportbeton e.V. wurden auf der Grundlage des hier dargestellten Bemessungskonzepts Typenstatiken nach DIN 1045‐1 [5] und DIN 1045 [6] aufgestellt.
Neue Konstruktionsprinzipien bei Tunnelinnenschalen
Authors: Hemmy Olaf , Falkner Horst 
Published: May 2004

AbstractDurch Bewehrungs‐ und Querschnittsoptimierung können das Gebrauchs‐ und Tragverhalten von Tunnelinnenschalen verbessert werden. Der Beitrag zeigt die Vorgangsweise. Insbesondere durch einen beschleunigten Baufortschritt ist mit Wettbewerbsvorteilen zu rechnen. Eine höhenreduzierte Schale aus Stahlfaserbeton bzw. stahlfaserverstärktem Stahlbeton erweist sich als besonders geeignet für den Lastabtrag einer Tunnelinnenschale — vor allem im Hinblick auf die Rißentwicklung im Gebrauchszustand, die bei einer wasserdichten Schale i. d. R. bemessungsrelevant ist, als vorteilhaft gegenüber einer konventionellen Schale aus Stahlbeton.
Spritzbeton — der etwas andere Beton
Authors: Pittino Gerhard , Gharehkhani Ghorbanali , Krenn Florian , Stelzer Gernot , Golser Johann 
Published: May 2004

AbstractSpritzbeton ist ein wesentliches Stützmittel bei der „Neuen Österreichischen Tunnelbaumethode”︁. Die Besonderheit des Tunnelausbaus mit Spritzbeton besteht darin, daß bereits dem jungen, noch im Erhärtungsprozeß befindlichen Spritzbeton große Verformungen aufgezwungen werden.Die Beurteilung der Tragreserve von Spritzbeton über den Beanspruchungsgrad erfordert die Kenntnis seiner i. a. mit der Zeit veränderlichen Spannungen und Festigkeiten. Die problematische Spannungsmessung mittels hydraulischer Druckmeßdosen wird durch Verschiebungs‐ bzw. Dehnungsmessungen und eine Spannungs‐Dehnungsbeziehung ersetzt, die eine Spannungsberechung aus den gemessenen Dehnungen ermöglicht.
Anwendung der neuen Stahlbetonnormen für die Bemessung von Tunnelinnenschalen
Authors: Mattle Bruno , Maier Klemens , Steiner Martin 
Published: May 2004

AbstractDie in den letzten Jahren in der Bundesrepublik Deutschland und in Österreich errichteten Verkehrstunnel wurden i. a. zweischalig, d. h. mit einer Spritzbetonaußenschale und einer Innenschale aus unbewehrtem Beton oder Stahlbeton hergestellt. Die Bemessung der Innenschalen erfolgte unter Anwendung der Normen DIN 1045 [1] und ÖN B 4200 [2].Während die neuen Normen wie EC 2 [3], DIN 1045‐1 [4] und ÖN B 4700 [5] im Hochbau schon seit längerem Anwendung finden, ist deren Anwendung für die Bemessung von Tunnelschalen im wesentlichen noch Neuland. Dies betrifft insbesondere die Anwendung des Teilsicherheitskonzeptes und die Möglichkeit, die Schnittgrößen unter Anwendung nichtlinearer Stoffgesetze zu ermitteln. Im vorliegenden Beitrag wird die Problematik dargestellt und anhand von Beispielen der Einfluß unterschiedlicher Annahmen aufgezeigt.
Rißbreitennachweis für Kreisquerschnitte
Authors: Wiese Hans , Curbach Manfred , Speck Kerstin , Weiland Silvio , Eckfeldt Lars , Hampel Torsten 
Published: May 2004

AbstractBei Kreisquerschnitten wie z. B. Ortbetonpfählen wird häufig der Nachweis der Rißbreite vernachlässigt. Handelt es sich jedoch um vorwiegend momentenbeanspruchte Bauteile, kann u. U. dieser Nachweis maßgebend werden. In diesem Beitrag werden daher alle erforderlichen Grundlagen für das Führen des Rißbreitennachweises an Kreisquerschnitten bereitgestellt.
Modelling and analysis of differential VCOs
Authors: Buonomo A. , Schiavo A. Lo 
Published: May 2004

AbstractWe present a systematic non‐linear analysis of differential voltage controlled oscillators (VCOs), both bipolar and MOS. Using the standard device models, we derive the second‐order non‐linear equation describing the behaviour of these oscillators, which is formulated in a perturbation form. The solution of this equation is obtained as a particular case of the solution of the most general equation of second‐order oscillators, which is solved through a suitable perturbation method. Unlike a pure numerical analysis, simple analytical relationships are derived for predicting the steady‐state oscillation, its transient behaviour and for ascertaining the existence of a stable oscillation in differential VCOs. These relationships, leading to results which well agree with the SPICE simulations, are useful in both analysis and design. Copyright © 2004 John Wiley & Sons, Ltd.
A new murine model of humoral immuno‐deficiency specifically affects class switching to T‐independent antigens
Authors: Kuzin Igor I. , Ugine Gregory D. , Barth Richard K. , Shultz Leonard D. , Nahm Moon H. , Young Faith M. , Bottaro Andrea 
Published: May 2004

AbstractImmunoglobulin (Ig) isotype deficiencies are among the most common and least characterized humoral immunodeficiencies. A thorough understanding of their immunological and genetic features has been hampered by their extreme heterogeneity and the paucity of suitable animal models. Here, we report the initial characterization of a new mouse model with selective Ig deficiency. SENCARA mice display low serum IgG3 levels as well as severely deficient IgG3 responses to T cell‐independent (TI) type 1 and 2 antigens. However, despite the significant block in class switching, expression of activation‐induced deaminase and γ3 germ‐line transcription after TI antigen immunization are normal. IgG3 production in response to in vitro LPS stimulation was also normal, ruling out a specific defect in the Cγ3 switch machinery. A decrease in the number of peritoneal B1a cells and enlarged splenic marginal zones were observed. The immunodeficiency is inherited as an autosomal, semi‐dominant, essentially monogenic trait in SENCARA × C57BL/6 crosses. The SENCARA humoral immunodeficiency constitutes a novel immune phenotype, resembling human conditions such as IgG2 deficiency. This new mouse model will be of interest for the understanding of mechanisms involved in TI immune responses and may provide new insights into the molecular basis of human Ig deficiencies.
Synthesis and Polymerization Performance of PdII Complexes of New 2‐Hydroxyethyl‐Substituted Diphosphane Ligands
Authors: Meier Uwe W. , Thewalt Ulf , Debaerdemaeker Tony , Rieger Bernhard 
Published: May 2004

AbstractWe have synthesized a new diphosphane ligand, 1,3‐bis[(2‐hydroxyethyl)(phenyl)phosphanyl]propane (2*) (*: mixture of meso‐ and racemic diastereoisomers), and its corresponding neutral dichloro palladium(II) (3*), diiodo palladium(II) (4*), and dicationic diacetonitrile palladium(II) ditetrafluoroborate (5*) complexes. Separation of the 4 rac and 4 meso diastereoisomers was achieved by column chromatography and subsequent crystallization. Assignments of the particular complex geometries of 3 meso and 4 rac were facilitated by single‐crystal X‐ray diffraction analysis. After activation with MAO, complex 3* exhibits superior activity in the homopolymerization of 2‐norbornene relative to that of the dichloro PdII derivative of 1,3‐bis(diphenylphosphanyl)propane (dppp). Compound 5* and the dppp‐analogue possess similar catalytic potentials in ethylene/CO copolymerization experiments. Applying complex 5* to propylene/CO copolymerization leads to highly regio‐ and predominantly stereoregular polyketone materials. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Studies Related to the Chloro Titanium and Zirconium Complexes with [η5‐Cyclopentadienyldi(silylamido)] Ligands
Authors: Sudupe María , Cano Jesús , Royo Pascual , Herdtweck Eberhardt 
Published: May 2004

AbstractTrichloro complexes [M{η5‐C5H3[SiMe2(NHtBu)]2}Cl3] [M = Zr (2), Ti (3)] have been synthesized by reaction of the corresponding chlorides MCl4 with the lithium salt LiC5H3[SiMe2(NHtBu)]2 (1). Complexes 2 and 3 react with 2 equiv. of TiCl4 in toluene at 110°C to afford the di(chlorosilyl) derivatives [M{η5‐C5H3(SiMe2Cl)2}Cl3] [M = Ti (5), Zr (8)]. Intermediate formation of [Ti{η5‐C5H3[SiMe2(NHtBu)](SiMe2Cl)}Cl3] (4) has been proven by NMR spectroscopy. Reaction of 1 with TiCl4 (2 equiv.) in toluene at 110 °C in the presence of excess NEt3 has yielded the chloro‐silyl complex [Ti{η5‐C5H3(SiMe2Cl)(SiMe2‐η1‐NtBu)}Cl2] (7) through the intermediate formation of the amino‐silyl derivative [Ti{η5‐C5H3[SiMe2(NHtBu)] (SiMe2‐η1‐NtBu)}Cl2] (6). Reactions of di‐ansa‐[M{η5‐C5H3(SiMe2‐η1‐NtBu)2}R] and ansa‐[M{η5‐C5H3[SiMe2(NHtBu)] (SiMe2‐η1‐NtBu)}R2] (M = Ti, Zr; R = NMe2, CH2Ph) complexes with NEt3·HCl have afforded the dichloro derivatives [M{η5‐C5H3[SiMe2(NHtBu)] (SiMe2‐η1‐NtBu)}Cl2] [M = Ti (6), Zr (12)], the amine‐coordinated zirconium compound [Zr{η5‐C5H3 [SiMe2(NHtBu)](SiMe2‐η1‐NtBu)} Cl2(NMe2H)] (9) and the chloro‐benzyl titanium complex [Ti{η5‐C5H3[SiMe2(NHtBu)](SiMe2‐η1‐NtBu)}Cl(CH2Ph)] (11). Formation of the mono‐substituted chloroamido zirconium complex [Zr{η5‐C5H3[SiMe2 (NHtBu)](SiMe2‐η1‐NtBu)}Cl(NMe2)] (10) by the reaction of [Zr{η5‐C5H3[SiMe2(NHtBu)] (SiMe2‐η1‐NtBu)}(NMe2)2] with SiClMe3 has been monitored in C6D6 by NMR spectroscopy. All of the new chloro complexes have been characterized by elemental analyses and NMR spectroscopy and the X‐ray crystal structure of [Ti(η5‐C5H3{SiMe2(NHtBu)}2)Cl3] (3) has been studied by diffraction methods. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Engineering and Prosthetic‐Group Modification of Myoglobin: Peroxidase Activity, Chemical Stability and Unfolding Properties
Authors: Roncone Raffaella , Monzani Enrico , Nicolis Stefania , Casella Luigi 
Published: May 2004

AbstractThe role of myoglobin (Mb) is not yet completely understood and recent evidence indicates it is involved in a variety of pseudo‐enzymatic functions. Mb is also extensively used as a tool to redesign novel active‐site features and introduce new activities into a protein. This review summarizes our approach to enhance the peroxidase‐like activity of Mb toward phenolic compounds by combining two different strategies of protein modification, i.e. active‐site engineering and cofactor replacement. The main objective of active‐site engineering is to increase the rate of hydrogen peroxide activation upon reaction at the iron(III) center, while cofactor replacement facilitates substrate interaction at the protein active site, thereby increasing the efficiency of the catalytic process and stereoselective recognition of the substrate. The thermodynamic stability of the modified Mb derivatives has been evaluated through guanidinium chloride induced and thermal unfolding experiments. As expected, both protein mutation and cofactor replacement decrease the stability of the protein, the latter effect being somewhat more pronounced for the Mb derivatives studied here. For evaluating the catalytic efficiency of the protein in non‐natural reactions, the chemical stability of the protein during catalysis is also important and therefore a new protocol was developed to evaluate the competitive degradation undergone by the protein upon substrate oxidation. It was found that autodegradation can occur through two different pathways involving oxidation of protein residues by the Mb active species or by a substrate‐derived phenoxy radical. The peroxidase‐like nitrating activity and the sulfoxidation reactions promoted by Mb, both involving the nitrite ion as a cosubstrate, have also been briefly described. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Preparation of Diamidochloro(cyclopentadienyl)titanium Derivatives as Pre‐Catalysts for Olefin Polymerization − X‐ray Molecular Structure of [Ti(η5‐C5H5){1,2‐C6H4(NCH2CH2CH3)2}Cl] and [Ti{η5‐C5H4(SiMe3)}{1,2‐C6H4(NCH2CH2CH3)2}Cl]
Authors: Tabernero Vanessa , Cuenca Tomás , Herdtweck Eberhardt 
Published: May 2004

AbstractThe synthesis of N,N′‐alkyl 1,2‐phenylenediamines 1,2‐C6H4(NHR)2 [R = CH2CH2CH3 (nPr), CH2tBu (Np)] was carried out in three steps by lithiation of the primary 1,2‐phenylenediamine, reaction with the appropriate acyl chloride and reduction with LiAlH4. The addition of nBuLi to a stirred solution of N,N′‐alkyl diamines in cold hexane resulted in the immediate deposition of the corresponding lithium salts, which react with [MCpR′Cl3] to give the diamidochloro(η5‐cyclopentadienyl)titanium and ‐zirconium complexes [MCpR′{1,2‐C6H4(NR)2}Cl] (4−10) [M = Ti, Zr; CpR′ = η5‐C5H5, η5‐C5(CH3)5, η5‐C5H4(SiMe3); R = nPr, Np]. The compound [Ti(η5‐C5H5){1,2‐C6H4(NnPr)2}Cl] (3) was obtained by treatment of [Ti(η5‐C5H5)Cl3] with 1,2‐C6H4(NHnPr)2 in the presence of NEt3 in toluene. All the reported compounds were characterized by the usual analytical and NMR spectroscopic methods. The molecular structures of 3 and 7 were determined by single‐crystal X‐ray crystallography. The compounds described here were further investigated as potential olefin polymerization catalysts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Joint compensation of IQ imbalance, frequency offset and phase noise in OFDM receivers
Authors: Tubbax Jan , Van der Perre Liesbet , Donnay Stéphane , Engels Marc , Moonen Marc , De Man Hugo 
Published: May 2004

AbstractZero‐IF receivers are getting a lot of attention because of their potential to enable low‐cost OFDM terminals. However, zero‐IF receivers also introduce IQ imbalance which can have a huge impact on the performance. Rather than increasing component cost to decrease the IQ imbalance, an alternative is to tolerate the IQ imbalance and compensate for it digitally. Current solutions either require additional analog hardware or are based on digital algorithms that converge too slowly for bursty communication. Moreover, the impact of a frequency offset and phase noise on the IQ imbalance estimation/compensation problem is not considered. In this paper, we analyze the joint IQ imbalance/frequency offset/phase noise estimation and propose a low‐cost, highly effective, all‐digital mitigation scheme. For large IQ imbalance large frequency offsets and in the presence of phase noise our solution still results in an average implementation loss below 0.5 dB. It, therefore, enables the design of low‐cost, lowcomplexity OFDM receivers. Copyright © 2004 AEI
Development of a convection–diffusion‐reaction magnetohydrodynamic solver on non‐staggered grids
Authors: Sheu Tony W. H. , Lin R. K. 
Published: May 2004

AbstractThis paper presents a convection–diffusion‐reaction (CDR) model for solving magnetic induction equations and incompressible Navier–Stokes equations. For purposes of increasing the prediction accuracy, the general solution to the one‐dimensional constant‐coefficient CDR equation is employed. For purposes of extending this discrete formulation to two‐dimensional analysis, the alternating direction implicit solution algorithm is applied. Numerical tests that are amenable to analytic solutions were performed in order to validate the proposed scheme. Results show good agreement with the analytic solutions and high rate of convergence. Like many magnetohydrodynamic studies, the Hartmann–Poiseuille problem is considered as a benchmark test to validate the code. Copyright © 2004 John Wiley & Sons, Ltd.
Prediction of unsteady, separated boundary layer over a blunt body for laminar, turbulent, and transitional flow
Authors: Holloway D. Scott , Walters D. Keith , Leylek James H. 
Published: May 2004

AbstractThe focus of this paper is to study the ability of unsteady RANS‐based CFD to predict separation over a blunt body for a wide range of Reynolds numbers particularly the ability to capture laminar‐to‐turbulent transition. A perfect test case to demonstrate this point is the cylinder‐in‐crossflow for which a comparison between experimental results from the open literature and a series of unsteady simulations is made. Reynolds number based on cylinder diameter is varied from 104 to 107 (subcritical through supercritical flow). Two methods are used to account for the turbulence in the simulations: currently available eddy–viscosity models, including standard and realizable forms of the k–ε model; and a newly developed eddy–viscosity model capable of resolving boundary layer transition, which is absolutely necessary for the type and range of flow under consideration. The new model does not require user input or ‘empirical’ fixes to force transition. For the first time in the open literature, three distinct flow regimes and the drag crisis due to the downstream shift of the separation point are predicted using an eddy–viscosity based model with transition effects. Discrepancies between experimental and computational results are discussed, and difficulties for CFD prediction are highlighted. Copyright © 2004 John Wiley & Sons, Ltd.
Flavonoids from the Resin of Dracaena cochinchinensis
Authors: Zheng Qing‐An , Li Hai‐Zhou , Zhang Ying‐Jun , Yang Chong‐Ren 
Published: May 2004

AbstractChemical investigation of the red herbal resin of Dracaena cochinchinensis resulted in the isolation of three new configurationally isomeric flavonoids: 6,4′‐dihydroxy‐7‐methoxy‐8‐methylflavane (=3,4‐dihydro‐2‐(4‐hydroxyphenyl)‐7‐methoxy‐8‐methyl‐2H‐[1]benzopyran‐6‐ol; 1), 5,4′‐dihydroxy‐7‐methoxy‐6‐methylflavane (=3,4‐dihydro‐2‐(4‐hydroxyphenyl)‐7‐methoxy‐6‐methyl‐2H‐[1]benzopyran‐5‐ol; 2), and 7,4′‐dihydroxy‐5‐ methoxyhomoisoflavane (=3,4‐dihydro‐3‐[(4‐hydroxyphenyl)methyl]‐5‐methoxy‐2H‐[1]benzopyran‐7‐ol; 3). Their structures were identified by means of detailed spectral analysis. In addition, thirteen known compounds were isolated from D. cochinchinensis: 7‐hydroxy‐4′‐methoxyflavane (4), 2,4,6‐trimethoxy‐4′‐hydroxydihydrochalcone (5), 2,4‐dimethoxy‐4′‐hydroxydihydrochalcone (6), 7,8‐(methylenedioxy)‐4′‐hydroxyhomoisoflavane (7), 4′,7‐dihydroxy‐8‐methylflavane (8), 2,6‐dimethoxy‐4,4′‐dihydroxydihydrochalcone (9), 2‐methoxy‐4,4′‐dihydroxydihydrochalcone (10), 7‐methoxy‐6,4′‐dihydroxyhomoisoflavane (11), 2‐methoxy‐4,4′‐dihydroxychalcone (12), 4′,7‐dihydroxyflavane (13), 7,4′‐dihydroxyhomoisoflavane (14), 7,4′‐dihydroxyhomoisoflavone (15), and 7,4′‐dihydroxyflavone (16). Compounds 7, 8, 9, 14, and 15 have been isolated for the first time from this type of herbal source.
Chemical Constituents from the Fruits of Madhuca latifolia
Authors: Siddiqui Bina S. , Khan Shazia , Kardar M. Nadeem , Aslam Huma 
Published: May 2004

AbstractFrom the fruit coats of the medicinal plant Madhuca latifolia were isolated three new compounds, the triterpenoid madhucic acid (=3β‐(octanoyloxy)‐11‐oxoolean‐12‐en‐28‐oic acid; 1), the untypical isoflavone madhushazone (=9‐methoxy‐7‐(2,3,6‐trimethoxyphenyl)‐[1,3]dioxolo[4,5‐g][1]benzopyran‐8(8H)‐one; 2), and a bis(isoflavone) named madhusalmone (=5,14‐dimethoxy‐3,12‐bis(3,4,5‐trimethoxyphenyl)‐1,6,8,10,15,17‐hexaoxanaphtho[2′,3′: 6,7]cyclodeca[1,2‐b]naphthalene‐4,13(4H,13H)‐dione; 3), as well as eight known constituents, and their structures were elucidated by spectral analysis, including 2D‐NMR techniques.
Preparation of an Advanced Intermediate for the Synthesis of Stable Analogues of Guanofosfocin
Authors: George Tesmol G. , Szolcsányi Peter , Koenig Stefan G. , Paterson Duncan E. , Isshiki Yoshiaki , Vasella Andrea 
Published: May 2004

AbstractThe synthesis of C‐mannosyl‐guanosine 23, an advanced intermediate for the preparation of stable analogues of guanofosfocin, is described. This convergent approach features an improved Traube‐type synthesis of a 8‐substituted guanine, followed by ribosylation. NMR Studies show that the C‐mannopyranosyl moiety of 23 adopts a distorted 1C4 conformation while the nucleoside is predominantly syn‐oriented.
Injectable microparticle‐gel system for prolonged and localized lidocaine release. I. In vitro characterization
Authors: Chen Pen‐Chung , Park Yoon Jeong , Chang Li‐Chien , Kohane Daniel S. , Bartlett Robert H. , Langer Robert , Yang Victor C. 
Published: May 2004

AbstractCurrent treatment protocol for postoperative pain is to infuse anesthetic solution around nerves or into the epidural space. This clinical practice is beset by the short duration of the anesthetic effect unless the infusion is continuous. Continuous infusion, however, requires hospitalization of the patients, thereby increasing medical costs. In addition, it also causes systemic accumulation of the drug. We reported herein a novel treatment for the postoperative pain by applying to the surgical site a biodegradable microsphere‐gel system for prolonged and localized release of encapsulated anesthetic drugs. This lidocaine‐containing biodegradable poly(D,L‐lactic acid) (PLA) microsphere system, although being established previously by other investigators, was hindered by a burst release and a followed rapid release of the drug within several hours in vitro. In this article, we demonstrated that by a step‐by‐step modification of the formulation, prolonged release of lidocaine, up to several days in vitro, could be achieved. Differential scanning calorimetry revealed a lower glass transition temperature for these lidocaine‐loaded microspheres comparing to that of lidocaine‐free microspheres. This decreased Tg explained for the tendency of the lidocaine‐loaded microspheres to physically fuse at higher temperatures. In vitro studies showed that microspheres, when loaded with 35% lidocaine, yielded a threefold increase in the degradation rate. The molecular weight of PLA of the drug‐loaded microspheres was reduced by 50% within a period of 1 month. Based on the results (of prolonged lidocaine release and rapid PLA microsphere degradation), this lidocaine‐loaded PLA microsphere system could offer a simple solution to the treatment of postoperative pain. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 70A: 412–419, 2004