bluuebunny/crossref_metadata_2025_split huggingface dataset:
9‐Demethyl‐9‐haloretinals by Wadsworth−Emmons Coupling − Easy Preparation of Pure (all‐E), (9Z) and (11Z) Isomers
Authors: Wang Yajie , Woo Wei Sein , van der Hoef Ineke , Lugtenburg Johan 
Published: April 2004

Abstract5‐(2′,6′,6′‐Trimethyl‐1′‐cyclohexen‐1′‐yl)‐4‐penten‐2‐yn‐1‐al has been prepared in a one‐pot process starting from β‐ionone in almost quantitative yield. Using 1,4‐nucleophilic addition reactions, the corresponding 9‐Cl, 9‐Br, 9‐I β‐ionylideneacetaldehyde systems could be obtained in one step in quantitative yield as a mixture of (9Z) and (all‐E) isomers. Even the corresponding fluoro derivative could be obtained in good yield as (9Z) and (all‐E) isomers. In the case of a double bond having a halogen substituent, the IUPAC rules have the (E) nomenclature for a cis double bond and the (Z) for a trans double bond. Simple column chromatography gave the pure (9Z) and (all‐E) form. Optimizing the Wadsworth−Emmons coupling gave the corresponding (all‐E)‐ and (9Z)‐retinonitriles in quantitative yield. Subsequent DIBAL‐H reduction gave the corresponding retinals. For the preparation of the (11Z) isomers essential to vision, we found that Wadsworth−Emmons reactions with the diphenyl phosphonate group gave retinonitriles in quantitative yield, where the newly formed double bond is predominantly the (11Z) form (> 60%), together with the (9Z) isomer as minor component. The nitriles could be isolated in pure (9Z,11Z) and (9Z) forms by simple column chromatography. In the case of the (9Z,11Z)‐9‐demethyl‐9‐halo systems, a complication arose due to the unprecedented acid lability of these (9Z,11Z) aldehydes. By adjusting the DIBAL‐H reduction workup procedure, these aldehydes are now available in pure form. We used this strategy to rationally synthesize (11Z)‐retinal starting from β‐cyclocitral as a first test for the generality of our new approach. β‐Ionylideneacetaldehyde could be prepared in the (all‐E) form in almost quantitative yield. Extending the conjugated chain of this molecule gave an almost quantitative yield of a mixture containing 80% (11Z)‐retinal and 20% (all‐E) as the minor component. Simple column chromatography gave pure (11Z)‐retinal in 75% overall yield. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Comparison of miniplates and reconstruction plates in mandibular reconstruction
Authors: Shaw Richard J. , Kanatas A. N. , Lowe Derek , Brown James S. , Rogers Simon N. , Vaughan E. David 
Published: April 2004

AbstractDue to a processing error, an early version of this manuscript was inadvertently published online in Head & Neck on September 23, 2003. The publisher has replaced the incorrect version of the published article with the final, accepted version of the manuscript. For archival purposes, the earlier version is available by contacting the publisher at headandneck@wiley.com. This should be considered the definitive version of this article. Background. The aim of this study is to compare complication rates of miniplates versus reconstruction plates in the fixation of vascularized grafts into segmental mandibular defects.Methods. Retrospective analysis of 143 consecutive successful microvascular composite flaps performed between 1993 and 2001 was performed. Data were gathered from a computerized database, case notes and pathology reports. Complications were classified as dehiscence, infection, plate or bone removal.Results. In the series, 49% of patients received miniplates, and 51% received plates. No significant differences in complication rates were found between those grafts fixed with miniplates (27%) and those with reconstruction plates (30%). Plate choice was primarily determined by consultant preference. No significant differences were found in patient, defect, treatrnent, or follow‐up characteristics between the plate groups. Twenty‐nine percent of patients had at least one late complication at the reconstructed site, and this was higher (39%) in those who had postoperative radiotherapy.Conclusions. No evidence was found in this study that the increased rigidity offered by reconstruction plates influences the rate of plate or bone removal, infection, or plate exposure. Thus, the decision to use reconstruction or miniplates is not dependent on the rate of plate complications. © 2003 Wiley Periodicals, Inc. Head Neck 25:456–463, 2003
Mechanics considerations for microporous titanium as an orthopedic implant material
Authors: Thelen Sarah , Barthelat François , Brinson L. Catherine 
Published: April 2004

AbstractThis article investigates mechanics issues related to potential use of a recently developed porous titanium (Ti) material for load‐bearing implants. This material may have advantages over solid Ti of enhancing the bone–implant interface strength by promoting bone and soft tissue ingrowth and of reducing the bone–implant modulus mismatch, which can lead to stress shielding. Experimental data from ultrasound experiments and uniaxial compression testing on microporous Ti are presented. Analytic models to predict its elastic modulus and Poisson's ratio are discussed, including “structural” approaches (Gibson and Ashby's cellular solids) and a “composite material” approach (Mori–Tanaka). Finally, two‐dimensional finite element models based on optical micrographs of the material are presented. Simulations were performed for different conditions and levels of approximation. Results demonstrate that simple analytic models provide good estimates of the elastic properties of the porous Ti and that the moduli can be significantly reduced to decrease the mismatch between solid Ti and bone. The finite element simulations show that bone ingrowth will dramatically reduce stress concentrations around the pores. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 601–610, 2004
The effect of basic fibroblast growth factor on bone regeneration when released from a novel in situ setting tricalcium phosphate cement
Authors: Niedhart Christopher , Maus Uwe , Miltner Oliver , Gräber Hans G. , Niethard Fritz U. , Siebert Christian H. 
Published: April 2004

AbstractThe osteostimulative effect of the basic fibroblast growth factor is well known, but it is dose dependent, and release kinetic depends on interactions with the used carrier. The aim of our study was to determine the osteostimulative effect of a composite, consisting of an in situ setting tricalcium phosphate cement and basic fibroblast growth factor. A trepanation defect of 1.5 mm in the femur diaphysis of Sprague‐Dawley rats was filled with the in situ setting TCP cement combined with 0, 0.25, 2.5, or 25 μg rh bFGF, an autologous bone graft or left empty. The rats were euthanized after 1 and 3 weeks and examined by radiography, histology, histomorphometry, and bending test. The data were analyzed by the Wilcoxon and Kruskal‐Wallis test. All TCP groups with or without bFGF showed a good bony ingrowth with a close bone–cement contact. Osseous ingrowth was not influenced by the addition of the different doses of bFGF as shown by histomorphometry. Also, mechanical strength was not affected. In conclusion, the combination of this in situ setting cement with bFGF is not useful for clinical application. The reason of these negative results remains unclear: the osteostimulative effect of bFGF is well known, and the TCP–cement was used as a carrier for rhBMP‐2 successfully. These negative results may be due to a too slow or too fast release of bFGF from the cement. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 680–685, 2004
Influence of cross‐linked PMMA beads on the mechanical behavior of self‐curing acrylic cements
Authors: Vallo C. I. , Abraham G. A. , Cuadrado T. R. , San Román J. 
Published: April 2004

AbstractCross‐linked PMMA beads were prepared with the use of two cross‐linking agents with different chain lengths: triethylene glycol dimethacrylate (TEGDMA) and poly(ethylene glycol) dimethacrylate (PEGDMA). Beads containing 10 wt % TEGDMA and 2, 5, and 10 wt % PEGDMA were synthesized by suspension polymerization. Experimental cement formulations were prepared by replacing part of the PMMA powder phase by an equivalent weight of the cross‐linked beads. The mechanical behavior of the modified cements was carried out by testing the cements in flexure and compression. All cements displayed a higher flexural modulus, which was accompanied with a slight decrease in the flexural strength. The two‐parameter Weibull model, which was used to analyze the flexural strength data, gave a good representation of the fracture load distribution. In cements prepared with beads containing 2 and 5 wt % PEGDMA and 10 wt % TEGDMA, no improvement in the flexural strength was observed. Debonding of the particles from the matrix was considered responsible for the decreased flexural strength. On the contrary, cements prepared with different proportions of beads containing 10 wt % PEGDMA resulted in a markedly increased flexural strength compared with the unmodified cement. An improved reinforcing effect of the cross‐linked beads and a significant degree of bonding with the matrix in these cements account for the superior flexural strength compared with the other composite cements tested. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 407–416, 2004
Upper bounds on the general covering number Cλ(v, k, t, m)
Authors: Bertolo Riccardo , Bluskov Iliya , Hämäläinen Heikki 
Published: April 2004

AbstractA collection $\cal C$ of k‐subsets (called blocks) of a v‐set X (v) = {1, 2,…, v} (with elements called points) is called a t‐(v, k, m, λ) covering if for every m‐subset M of X (v) there is a subcollection $\cal K$ of $\cal C$ with $|\cal K|\geq \lambda$ such that every block K ∈ $\cal K$ has at least t points in common with M. It is required that v ≥ k ≥ t and v ≥ m ≥ t. The minimum number of blocks in a t‐(v, k, m, λ) covering is denoted by Cλ(v, k, t, m). We present some constructions producing the best known upper bounds on Cλ(v, k, t, m) for k = 6, a parameter of interest to lottery players. © 2004 Wiley Periodicals, Inc.
Biophysical and pharmacological characterization of spermatogenic T‐type calcium current in mice lacking the CaV3.1 (α1G) calcium channel: CaV3.2 (α1H) is the main functional calcium channel in wild‐type spermatogenic cells
Authors: Stamboulian Séverine , Kim Daesoo , Shin Hee‐Sup , Ronjat Michel , De Waard Michel , Arnoult Christophe 
Published: April 2004

AbstractMammalian acrosome reaction (AR) requires successive activation of three different types of calcium channels (T‐type channels, Inositol‐3‐phosphate (InsP3) receptors, and TRPC2 channels). All the calcium signaling is under the control of the activation of the first‐one, a T‐type calcium channel. The molecular characterization of the T‐type calcium channel is still a matter of debate, previous reports showing the presence of transcripts for CaV3.1 and CaV3.2 subunits. Using mice deficient for CaV3.1 subunit, we show that the T‐type current density in spermatogenic cells is not reduced in deficient mice versus control mice. We characterized the biophysical and pharmacological properties of T‐type current in spermatogenic cells from CaV3.1 deficient mice. Biophysical and pharmacological properties of spermatogenic T‐type current from wild‐type and CaV3.1 deficient mice demonstrate that CaV3.3 does not contribute to T‐type current. Moreover, nickel and amiloride inhibit T‐type currents in deficient and wild‐type mice with similar potencies. These results demonstrate that T‐type currents in spermatogenic cells is due to CaV3.2 subunit and that CaV3.1 contributes to a very negligible extent to the T‐type currents. Thus, the deficient CaV3.1 mouse model allows the characterization of native CaV3.2 currents in spermatogenic cells. Spermatogenic CaV3.2 currents present specific feature in comparison to the cloned CaV3.2 current so far. More particularly, the time‐dependence of recovery from short‐term inactivation of native spermatogenic CaV3.2 is close to 100 millisecond, a value expected for CaV3.1 current. © 2003 Wiley‐Liss, Inc.
Separation of carbon nanotubes by frit inlet asymmetrical flow field‐flow fractionation
Authors: Moon Myeong Hee , Kang Dukjin , Jung Jaehong , Kim Jongmin 
Published: April 2004

AbstractFlow field‐flow fractionation (flow FFF), a separation technique for particles and macromolecules, has been used to separate carbon nanotubes (CNT). The carbon nanotube ropes that were purified from a raw carbon nanotube mixture by acidic reflux followed by cross‐flow filtration using a hollow fiber module were cut into shorter lengths by sonication under a concentrated acid mixture. The cut carbon nanotubes were separated by using a modified flow FFF channel system, frit inlet asymmetrical flow FFF (FI AFlFFF) channel, which was useful in the continuous flow operation during injection and separation. Carbon nanotubes, before and after the cutting process, were clearly distinguished by their retention profiles. The narrow volume fractions of CNT collected during flow FFF runs were confirmed by field emission scanning electron microscopy and Raman spectroscopy. Experimentally, it was found that retention of carbon nanotubes in flow FFF was dependent on the use of surfactant for CNT dispersion and for the carrier solution in flow FFF. In this work, the use of flow FFF for the size differentiation of carbon nanotubes in the process of preparation or purification was demonstrated.
In‐situ diffraction investigation of superelastic NiTi shape memory alloys under mechanical stress with neutrons and with synchrotron radiation
Authors: Khalil‐Allafi J. , Hasse B. , Klönne M. , Wagner M. , Pirling Th. , Predki W. , Schmahl W.W. 
Published: April 2004

AbstractIn‐situ diffraction investigations of superelastic NiTi shape memory alloys with neutron and synchrotron x‐ray radiation were used to examine the evolution of the phase state of the material as a function of stress and strain, respectively. The results suggest that the transition from austenite to martensite is not complete even at the end of the superelastic plateau, and that significant load transfer to residual austenite takes place.
Knowledge and Method Base for Shape Memory Alloys
Authors: Welp E. G. , Breidert J. 
Published: April 2004

AbstractIt is often impossible for design engineers to decide whether it is possible to use shape memory alloys (SMA) for a particular task. In case of a decision to use SMA for product development, design engineers normally do not know in detail how to proceed in a correct and beneficial way. In order to support design engineers who have no previous knowledge about SMA and to assist in the transfer of results from basic research to industrial practice, an essential knowledge and method base has been developed. Through carefully conducted literature studies and patent analysis material and design information could be collected. All information is implemented into a computer supported knowledge and method base that provides design information with a particular focus on the conceptual and embodiment design phase. The knowledge and method base contains solution principles and data about effects, material and manufacturing as well as design guidelines and calculation methods for dimensioning and optimization. A browser‐based user interface ensures that design engineers have immediate access to the latest version of the knowledge and method base. In order to ensure a user friendly application, an evaluation with several test users has been carried out. Reactions of design engineers from the industrial sector underline the need for support related to knowledge on SMA.
Algorithms for a network design problem with crossing supermodular demands
Authors: Melkonian Vardges , Tardos Éva 
Published: April 2004

AbstractWe present approximation algorithms for a class ofdirectednetwork design problems. The network design problem is to find a minimum cost subgraph such that for each vertex setSthere are at leastf(S) arcs leaving the setS. In the last 10 years general techniques have been developed for designing approximation algorithms forundirectednetwork design problems. Recently, Kamal Jain gave a 2‐approximation algorithm for the case when the functionfis weakly supermodular. There has been very little progress made ondirectednetwork design problems. The main techniques used for the undirected problems do not have simple extensions to the directed case. András Frank has shown that in a special case when the functionfis intersecting supermodular the problem can be solved optimally. In this article, we use this result to get a 2‐approximation algorithm for a more general case whenfis crossing supermodular. We also extend Jain's techniques to directed problems. We prove that if the functionfis crossing supermodular, then any basic solution of the LP relaxation of our problem contains at least one variable with value greater or equal to ¼. This result implies a 4‐approximation algorithm for the class of directed network design problems. © 2004 Wiley Periodicals, Inc.
What is the appropriate role of the trial statistician in preparing and presenting interim findings to an independent Data Monitoring Committee in the U.S. Cancer Cooperative Group setting?
Authors: Bryant John 
Published: April 2004

AbstractA recent draft FDA Guidance on the establishment and operation of clinical trial Data Monitoring Committees (DMCs) suggests that statisticians who prepare and present interim analyses to the DMC should be external to the trial sponsor. In the context of the National Cancer Institute (NCI) Cooperative Group program, this recommendation appears to imply that Group study statisticians should be blinded to interim data and excluded from the interim monitoring process in all Cooperative Group trials. In this commentary, it is argued that the benefits of such a policy would be minimal in the Cooperative Group setting and are far outweighed by the tangible benefits of including the study statistician in the monitoring process. Copyright 2004 John Wiley & Sons, Ltd.
A major trial needs three statisticians: why, how and who?
Authors: Pocock Stuart J. 
Published: April 2004

AbstractThe statistical and scientific integrity of a major clinical trial is enhanced by having three distinct statistician roles: the Study Statistician, the Data Monitoring Committee (DMC) Statistician and the Independent Statistician. In any specific trial, careful attention should be given for selecting the right people to perform these tasks effectively. It is important that there are good communications amongst all three statisticians (and between each statistician and the other trialists) while preserving all confidentiality as regards interim results. Specifically regarding the Independent Statistician, it seems appropriate that they be truly independent having no other trial involvement than producing interim reports that inform the DMC (and be not employed by a commercial sponsor) but at the same time be fully aware of the trial protocol, objectives, organization and database. Copyright © 2004 John Wiley Sons, Ltd.
Swelling Characteristics of Native and Chemically Modified Wheat Starches as a Function of Heating Temperature and Time
Authors: Choi Sung‐Gil , Kerr William L. 
Published: April 2004

AbstractThe effects of hydroxypropylation (molar substitution, MS 0.05, 0.12, and 0.18) and cross‐linking (0.03%, 0.1%, and 0.2%) on swelling properties of wheat starch granules at several temperatures and heating times were investigated by laser diffraction particle size analysis. Starch samples were dispersed in water at temperatures ranging from 30 to 90°C, for 1 to 360 min. All starch granules exhibited distinct bimodal size distributions: small B‐granules with mean diameter of 2.3 μm and large A‐granules with mean diameter of 20.4 μm. As temperature increased, the B‐granules swelled more than A‐granules. Swelling of A‐granules sharply increased at 60°C. Swelling was more pronounced with increasing molar substitution of hydroxypropyl groups, while increased swelling was not observed in cross‐linked starches. The dependence of swelling capacity on heating time was different at 60 and 80°C as well as amongst modified starches. As heating time was prolonged, mean granule sizes for native, control, and hydroxypropylated starches at 80°C decreased after reaching maximum size due to loss of granule integrity, while those at 60°C showed no significant change.
Comparing model checking and logical reasoning for real-time systems
Authors: Dierks Henning 
Published: April 2004

Abstract.
We apply both model checking and logical reasoning to a real-time protocol for mutual exclusion. To this end we employ PLC-Automata, an abstract notion of programs for real-time systems. A logic-based semantics in terms of Duration Calculus is used to verify the correctness of the protocol by logical reasoning. An alternative but consistent operational semantics in terms of Timed Automata is used to verify the correctness by model checkers. Since model checking of the full model does not terminate in all cases within an acceptable time we examine abstractions and their influence on model-checking performance. We present two abstraction methods that can be applied successfully for the protocol presented.
Pharyngeal acid Reflux in Patients with Single and Multiple Otolaryngologic Disorders
Authors: Ulualp Seckin O. , Toohill Robert J. , Shaker Reza 
Published: April 2004

OBJECTIVEThis study was designed to determine the prevalence and characteristics of pharyngeal acid reflux (PAR) events in single and multiple otolaryngologic disorders.METHODSSixty‐seven patients with otolaryngologic symptoms and objective findings and 34 healthy control subjects were studied with an ambulatory 24‐hour, 3‐site pharyngoesophageal pH monitoring technique. Otolaryngologic diagnosis included isolated Posterior laryngitis (PL) in 28 patients, isolated chronic rhinosinusitis (SIN) in 12, combined PL and SIN (PL+SIN) in 6, PL plus laryngotracheal stenosis (PL+LTS) in 12, and PL plus vocal cord nodules (PL+VCN) in 9.RESULTSPAR events were documented in 68% of patients with PL, 34% of patients with SIN, 67% of patients with PL+SIN, 67% of patients with PL+LTS, 78% of patients with PL+VCN, and 21% of controls. The prevalence of PAR events in patients with isolated PL as well as those with PL combined with other disorders was significantly higher than that in patients without PL and that in controls. As a group, patients with PL had a greater number of PAR events and acid exposure time than other patients and controls. Distal and proximal esophageal reflux parameters were not significantly different among groups.CONCLUSIONSThe prevalence of PAR is significantly higher in patients with isolated PL compared to patients with other isolated otolaryngologic disorders and in controls. The prevalence of PAR in isolated otolaryngologic disorders other than PL is similar to that in healthy controls. The prevalence of PAR is significantly higher in patients with both PL and other otolaryngologic disorders than in controls and in patients with isolated otolaryngologic disorders.
Secondary Intention Healing of Exposed Scalp and Forehead Bone after Mohs Surgery
Authors: Becker Gary D. , Adams Lawrence A. , Levin Barry C. 
Published: April 2004

For Mohs surgical wounds that show exposed bone (ie, bone denuded of periosteum), healing by secondary intention may be preferable to surgical reconstruction. To determine the appropriateness of secondary intention healing, we reviewed surgical outcome in 205 patients with Mohs wounds of the scalp and forehead that had healed by secondary intention. Of these patients, 38 had Mohs wounds showing exposed bone. The mean area of exposed bone was 1074 mm2; the mean area of exposed soft tissue was 1575 mm2. The mean time for wounds with intact periosteum to epithelialize was 7 weeks; the mean time for bare bone to epithelialize was 13 weeks. All wounds healed without infection or tissue breakdown. We conclude that secondary intention healing of scalp and forehead wounds showing exposed bone is a safe and effective method of wound management after Mohs surgery.