bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Gilch Synthesis of Poly(p‐phenylene vinylenes): Mechanistic Knowledge in the Service of Advanced Materials
Authors: Schwalm Thorsten , Wiesecke Jens , Immel Stefan , Rehahn Matthias 
Published: April 2009

AbstractA consistent picture is presented of the mechanistic details and intermediates of the Gilch polymerization leading to poly(p‐phenylene vinylenes) (PPVs). In‐situ generated p‐quinodimethanes are shown to be the real monomers, and spontaneous formation of the initiating radicals is effected by dimerization of some of these monomers to dimer diradicals, the latter also being the reason why significant amounts of [2.2]paracyclophanes are formed as side‐products. Chain propagation predominantly proceeds by radical chain growth, occasionally interrupted by polyrecombination events between the growing α,ω‐macro‐diradicals. Based on this knowledge, oxygen is identified as a very efficient molar‐mass regulating agent, and the temporary gelation of the reaction mixtures is interpreted to be the consequence of a very high entanglement of the polymers immediately after their formation. Last but not least, it is rationalized why the usually considered constitutional defects in Gilch PPVs might not be the only and most relevant ones with respect to the efficiency and durability of the organic light emitting devices produced thereof, and why cis‐configurated halide‐bearing vinylene moieties should be perceived as being among the most critical candidates. These considerations result in the recommendation of straightforward measures that should lead to clearly improved PPVs.magnified image
Calcium phosphate scaffolds fabricated via chemical bonding technique from different precursors
Authors: Kuznetsov A. , Larionov D. , Stepuk A. , Kuznetsov V. , Putlayev V. , Ivanov V. 
Published: April 2009

AbstractCalcium phosphate bulk materials were fabricated via chemical bonding technique with the use of α‐tricalcium (TCP) and amorphous calcium phosphates (ACP) as binders at temperatures below 90 °C. The bonding technique included preparation of pastes of the binders with water, pressing the pastes into dense cylinders, and then hardening the cylinders in hot water. During the last step, hydrolytic conversion of TCP and ACP into small interpenetrating hydroxyapatite (HAp) crystals took place, providing pressed pastes of the binders with appropriate strength. The kinetics of α‐TCP hydrolysis leads to two distinct scaffold microstructures composed of platelet or needle‐like HAp crystals. Under optimal conditions of the bonding, the resulting materials demonstrated compressive strengths up to 90 MPa (and up to 145 MPa, when sodium citrate modifier of the paste is used), which is close to that one of a cortical bone. In contrast to TCP, ACP‐based samples exhibited lower strength, limiting them to use as non‐load bearing implant materials. To enhance mechanical properties, composites containing crystalline phases of HAP, β‐TCP and CaCO3 bonded by ACP binder were proposed. Low value of strength obtained for ACP‐based materials was attributed to extensive cracking resulted from stresses developing under setting of ACP.
Materials and coatings based on biopolymer‐apatite nanocomposites: obtaining, structural characterization and in‐vivo tests
Authors: Sukhodub L. 
Published: April 2009

AbstractPresent paper discusses the results obtained for three different nanocomposite systems, namely chitosan‐apatite, hydrogel‐HA and collagen‐apatite coatings onto Ti6Al4V substrates. Common analytical techniques such as X‐ray diffraction analysis, infrared spectroscopy, scanning electron microscopy with X‐ray dispersive energy analysis were employed to characterize the resulting materials. Special attention was given to the in‐vivo tests of the obtained chitosan‐apatite composites using 48 linear laboratory rats at the age of 4 months. Using energy dispersive X‐ray analysis (EDX) of HA nanoclusters, formed in hydrogel nanoreactor matrixes, the process of their formation depending on monomer nature and ratio, as well as on their consistent state was optimized. In case of microgranules based on homopolyacrylamide gel we observed almost ideal coincidence on the stochiometric composition with pure HA (Ca/P=1.67). Thermal substrate method recently proposed to obtain hydroxyapatite coating on titanium was used for high crystallinity hydroxyapatite deposition onto titanium‐based plate (TiAlV) at the physiological temperature. The coating was produced onto clear plates and onto collagen covered surfaces. The best pH value for depositing of the high crystallinity hydroxyapatite on a target was pH 6,15. Depositing speed was decreased with pH decreasing, and while pH value was increased up to 6,3 crystallinity was going down. Collagen has improved both the speed and the crystallinity of the deposited layers.
Epigenetic modulation of the retinoid X receptor α by green tea in the azoxymethane‐ApcMin/+ mouse model of intestinal cancer
Authors: Volate Suresh R. , Muga Stephanie J. , Issa Ala Y. , Nitcheva Daniela , Smith Theresa , Wargovich Michael J. 
Published: April 2009

AbstractWe investigated the possible mechanisms of inhibition of colorectal carcinogenesis by green tea (GT) in azoxymethane‐treated (AOM) ApcMin/+ mice. Mice received water or a 0.6% (w/v) solution of GT as the only source of beverage. GT treatment commenced at the 8th week of age and lasted for 8 wk. The treatment caused a statistically significant reduction in the number of newly formed tumors (28%, P < 0.05). Immunohistochemical analysis showed that GT decreased the levels of β‐catenin and its downstream target cyclin D1. To probe a mechanism, we further investigated the expression of retinoic X receptor alpha (RXRα) in AOM/ApcMin/+ tumors. Our results show that RXRα is selectively downregulated in AOM/ApcMin/+ mouse intestinal tumors. In contrast, other retinoic receptors including retinoic acid receptor alpha (RARα), RARβ, RXRβ, and RXRγ were all expressed in ApcMin/+ adenomas. Furthermore, our results show that RXRα downregulation is an early event in colorectal carcinogenesis and is independent of β‐catenin expression. GT significantly increased the protein levels of RXRα. In addition, RT‐PCR analysis showed that GT induced a similar increase in the levels of RXRα mRNA. Genomic bisulfite treatment of colonic DNA followed by pyrosequencing of 24 CpG sites in the promoter region of RXRα gene showed a significant decrease in CpG methylation with GT treatment. The results suggest that a low concentration of GT is sufficient to desilence RXRα and inhibit intestinal tumorigenesis in the ApcMin/+ mouse. Mol. Carcinog. © 2009 Wiley‐Liss, Inc.
Symptom and gait changes after sensory attention focused exercise vs aerobic training in Parkinson's disease
Authors: Sage Michael D. , Almeida Quincy J. 
Published: April 2009

AbstractThe current study compared lower‐limb aerobic training and sensory attention focused exercise (PD SAFEx) to a non‐exercise control group with the overall objective of determining which strategy would have a greater benefit for Parkinson's disease (PD) symptoms and gait. PD SAFEx was developed to focus on sensorimotor deficits identified in PD with the aim of increasing sensory feedback and body awareness, while the lower‐limb aerobic training utilized a specially designed semi‐recumbent elliptical device. Intervention groups (PD SAFEx, n = 18; aerobic, n = 13) exercised three times/week for 10–12 weeks, while nonexercise control participants (n = 15) maintained their regular activity level for 12 weeks. Outcome measures included the Unified Parkinson's disease rating scale motor section (UPDRS) administered by a blinded clinician; a posture and gait (PG) score (total of UPDRS items 27–31); the Timed‐Up‐and‐Go (TUG); and spatiotemporal aspects of self‐paced gait. PD SAFEx resulted in an improved UPDRS, PG score, and TUG (reached significance when participants with poor attendance were excluded) but not self‐paced gait. The lower‐limb aerobic training led to increased step length and velocity but had no change to disease severity. Since gait improvements were not combined with symptomatic changes, lower‐limb aerobic exercise may not be optimal for individuals with PD. Conversely, sensory‐based exercise (PD SAFEx) was beneficial, and led to improvement in symptoms and functional movement control. © 2009 Movement Disorder Society
Recent developments in anti‐inflammatory natural products
Authors: Gautam Raju , Jachak Sanjay M. 
Published: April 2009

AbstractMany of the inflammatory diseases are becoming common in aging society throughout the world. The clinically used anti‐inflammatory drugs suffer from the disadvantage of side effects and high cost of treatment (in case of biologics). Alternative to these drugs are traditional medicines and natural products, which offer a great hope in the identification of bioactive lead compounds and their development into drugs for treating inflammatory diseases. Since ancient times traditional medicines and phytopharmaceuticals are being used for the treatment of inflammatory and other disorders. The present review article describes anti‐inflammatory natural products derived from plants and marine sources reported during last decade. The compounds described belong to different chemical classes such as alkaloids, steroids, terpenoids, polyphenolics, phenylpropanoids, fatty acids and lipids, and various miscellaneous compounds. The attempt is also being made to enumerate the possible leads, e.g. curcumin, resveratrol, baicalein, boswellic acid, betulinic acid, ursolic acid, and oleanolic acid, for further development with the help of structure–activity relationship (SAR) studies and their current status. In addition SAR studies carried out on the anti‐inflammatory activity of flavonoid compounds and clinical studies performed on anti‐inflammatory natural products are also discussed. © 2009 Wiley Periodicals, Inc. Med Res Rev, 29, No. 5, 767–820, 2009
Characterization of the cellular immune response in hepatitis C virus infection
Authors: Zhang Xinjian , Dou Jun , Germann Markus W. 
Published: April 2009

AbstractHepatitis C virus (HCV), a hepatotropic RNA virus, is a major causative agent of chronic hepatitis, liver cirrhosis, and hepatocellular carcinomas. The host immune responses, especially cellular immune responses, play an important role in viral clearance, liver injury, and persistent HCV infection. A thorough characterization of the HCV cellular immune responses is important for understanding the interplays between host immune system and viral components, as well as for developing effective therapeutic and prophylactic HCV vaccines. Recent advances that provide better understanding the cell immune responses in HCV infection are summarized in this article.  © 2009 Wiley Periodicals, Inc. Med Res Rev, 29, No. 6, 843–866, 2009
On the use of Standardized Precipitation Index (SPI) for drought intensity assessment
Authors: Naresh Kumar M. , Murthy C. S. , Sesha Sai M. V. R. , Roy P. S. 
Published: April 2009

AbstractMonthly rainfall data from June to October for 39 years were used to compute Standardized Precipitation Index (SPI) values based on two parameter gamma distribution for a low rainfall and a high rainfall districts of Andhra Pradesh state, India. Comparison of SPI with actual rainfall and rainfall deviation from the mean indicated that SPI values under‐estimate the intensity of dryness/wetness when the rainfall is very low/very high, respectively. As a result, the SPI in the worst drought years of 2002 and 2006 in the low rainfall district indicated only moderate dryness instead of extreme dryness. SPI values of the high rainfall district showed slightly better stretching in both positive and negative directions, compared to that of the low rainfall district. Further, the SPI values of longer time scales (2, 3 and 4 months) showed an extended range compared to that of 1 month, but the sensitivity in drought years has not improved significantly.Normality tests were conducted based on Shapiro‐Wilk statistic, p‐values and absolute value of the median to ascertain whether non‐normality of SPI is a possible reason. Although the results confirmed normal distribution, the scatter plot indicated deviation of the cumulative probability distribution of SPI from normal probability in the lower and upper ranges.Therefore, it is suggested that SPI as a stand alone indicator needs to be interpreted with caution to assess the intensity of drought. Further investigations should include sensitivity of SPI to the estimated shape and scale at lower and upper bounds of the gamma distribution and use of other distributions, such as Pearson III, to standardize the computational procedures, before using SPI as a substitute to the rainfall deviations from normal, for drought intensity assessment. Copyright © 2009 Royal Meteorological Society
A comparison of the rainfall patterns between stations on the East and the West coasts of Peninsular Malaysia using the smoothing model of rainfall amounts
Authors: Suhaila Jamaludin , Jemain Abdul Aziz 
Published: April 2009

AbstractThe aim of this study is to model rainfall amounts on a daily basis by fitting a smooth curve to the mean rainfallperrainy day. The rainfall amounts are described as gamma distributions with smoothing parameters. The smoothing technique used is the approach of the Fourier series. Six rain gauge stations with the daily rainfall series covering the same period (1975–2004) are examined. Different rainfall patterns are observed among the stations, particularly between the east and the west. The stations in the western area have a bimodal pattern of rainfall and are best described with two harmonics, while four harmonics are required for the stations in the eastern area which exhibit a unimodal pattern of rainfall. The resulting curves with fitted smoothing parameters provide a good summary of statistics and useful information for describing the rainfall patterns and climate of the studied stations. Copyright © 2009 Royal Meteorological Society
Regional daily maximum rainfall estimation for Cekerek Watershed by L‐moments
Authors: Yurekli Kadri , Modarres Reza , Ozturk Fazli 
Published: April 2009

AbstractThe estimation of maximum daily rainfall (PDmax) is usually required for the estimation of design flood (the maximum flood that any hydraulic structure can safely pass). However, PDmax estimation is usually required for watersheds where rainfall data are either not available or only available in short periods from various sites and so are unsuitable for maximum daily rainfall estimation. In this study, the regional PDmax of the Cekerek watershed in Turkey is estimated using the method of l‐moments using 17 rainfall stations in the region. The discordant test for outlier stations showed no discordant station in the region. Applying the homogeneity measure, Hi, the homogeneous region was identified. To find the best regional distribution, the ZDIST goodness‐of‐fit test was applied. This test introduced two distributions as the candidates for regional parent distributions; Generalized Extreme Values (GEV) and 3‐parameter Log Normal (LOGN3) distributions. The LOGN3 distribution was selected as the best regional distribution as it has the smaller absolute value of the statistics (ZDIST) based on the goodness‐of‐fit‐test. Copyright © 2009 Royal Meteorological Society
Regional scale spatio‐temporal consistency of precipitation variables related to water resource management and planning
Authors: Paynter Shayne , Nachabe Mahmood 
Published: April 2009

AbstractThe focus of this research was to determine the extent of spatio‐temporal changes in precipitation patterns using methods that can be regionalized and applied to various water resources such as lakes, streams, reservoirs or other water bodies. Many water resources throughout the world have demonstrated changes in historic water levels. As precipitation is the major input to these water bodies, it is important to investigate any changes in rainfall in both time and space. To investigate these patterns regionally, appropriate distributions, either gamma or generalized extreme value (GEV), were fitted to variables at a number of rainfall gauges within 40 km of a particular lake using maximum likelihood estimation. The variables included total annual rainfall, rainfall days per year, maximum annual event rainfall and maximum annual interevent days. Once the distribution parameters were estimated, an average, representative, distribution for each variable with 99% confidence limits was developed to determine if the fits for all gauges and variables were contained by these limits. To examine the temporal variation, distribution parameters were allowed to vary with time and then compared to constant parameter fits via likelihood ratio tests to determine if the varying parameter model significantly improved the fit. The spatial distribution of rainfall variables was found to be quite homogenous within the given confidence limits with some exceptions at high and low percentiles. Furthermore, the temporal distribution of rainfall variables was found to be stationary with only one gauge showing a significant trend. The average distribution for each precipitation variable developed can be applied at water resources within the region without rainfall gauges in proximity due to the spatial homogeneity and temporal stationarity identified. The methodology can be adapted to water resource management and planning in other regions. Copyright © 2009 Royal Meteorological Society
Vascularized free fibular bone graft in the management of congenital tibial pseudarthrosis
Authors: Korompilias Anastasios V. , Lykissas Marios G. , Soucacos Panayiotis N. , Kostas Ioannis , Beris Alexandros E. 
Published: April 2009

AbstractCongenital pseudarthrosis of the tibia (CPT) remains one of the most challenging problems confronting the orthopaedic surgeon. The operative results are frequently less than successful; many cases require several surgical procedures, and a significant number of them ending in amputation. The purpose of this study was to access the surgical results, complications, secondary procedures, and long‐term results of free vascularized fibular graft (FVFG) in the treatment of congenital pseudarthrosis of the tibia. Between 1992 and 2007, nine patients with CPT were treated consecutively at our clinic with free fibula transfer. There were six females and three males. The mean age at the time of operation was 6.5 years (range, 1–12 years). Stability, after reconstruction with FVFG, was maintained with internal fixation in five patients, unilateral frame external fixation in three patients, and intramedullary pin in one patient. Average postoperative follow‐up time was 9 years (range, 2–15 years). In seven patients, both ends of the graft healed primarily within 3.7 months (range, 1.5–6 months). In one patient, the distal end of the graft did not unit. This patient required three subsequent operations to achieve union. Stress fracture occurred in the middle of the grafted fibula in one patient, who underwent four additional operations before union, was achieved. Despite the relatively high‐complication rate, FVFG remains a valid method for the treatment of CPT. However, even achieving union of pseudarthrosis is not enough for the resolution of the disease. This is only half of the problem; the other half is to maintain union. Long‐term follow‐up beyond skeletal maturity, if possible, is necessary to evaluate surgical results. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.
The use of vascularized fibular grafts for the reconstruction of spinal and sacral defects
Authors: Moran Steven L. , Bakri Karim , Mardini Samir , Shin Alexander Y. , Bishop Allen T. 
Published: April 2009

AbstractBackground: Large segmental defects of the spine may result from tumor resection as well as infection. The surrounding soft tissue in these situations is often compromised due to radiation exposure or infection. In these situations, in which conventional bone grafting has often failed, we have found vascularized fibular grafts an effective method of achieving bony union. The purpose of this study was to review the results of vascularized bone grafting for complex spinal reconstruction using free fibular transfer. Methods: We performed a retrospective chart review of all patients who underwent multisegmental spinal reconstruction and pelvic reconstruction using posterior instrumentation and free fibula vascularized bone transfer. Results: Twelve patients underwent 14 free fibula transfers (7 anterior and 5 posteriorly placed) for reconstruction of lumbosacral spinal defects. Preoperative diagnoses included tumor, osteomyelitis, and nonunion. Average number of vertebral body resections was four and posterior instrumentation was used for all arthrodeses. Average duration of follow up was 45 months. Two flaps failed (14%), one resulting in nonunion and the other required salvage with an external hemipelvectomy. All remaining flaps healed at a mean time of 4.5 months (range, 3–10 months). Conclusion: Free fibula transfer for complex spinal reconstruction is a reliable means of obtaining bony union for complex lumbar or sacral resections where traditional bone grafting techniques may not be technically feasible. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.
Correlation of three sciatic functional indices with histomorphometric findings in a rat sciatic nerve allograft repair model
Authors: Rustemeyer Jan , Dicke Ursula 
Published: April 2009

AbstractWalking track analysis was used to measure global functional recovery following sciatic nerve injury. The correlation of morphologic outcome and different sciatic functional indices (SFIs) depends on different variables. The objective of this study was to compare three different SFIs and their correlation with histomorphometric findings in a sciatic nerve allograft repair model in the rat without (group I,n= 8) or with (group II,n= 8) daily intramuscular administration of 0.1 mg/kg FK 506. The correlation of SFIs with each other and with the myelin basic protein (MBP) density of nerve sections proximal, median, and distal to sciatic nerve grafts (1.5 cm) at 4, 8, 12, and 16 weeks postoperation (p.o.) was calculated, and unoperated animals served as controls (n= 8). Significant differences between SFIs calculated for experimental groups I and II at 12 and 16 weeks p.o. suggested that superior functional nerve recovery occurred in group II. However, there were significant differences between all SFIs at 16 weeks p.o. in group II, whereas only differences between SFI 1 and SFI 2 + 3 occurred in group I. SFIs of group II did not reach the values of the unoperated group. There were significant differences between the histomorphometric outcomes of groups I and II. There was no significant difference of MBP density between group II and the unoperated group, suggesting complete morphologic recovery. In conclusion, we found significant correlation between the MBP densities of groups I and II and all SFIs, suggesting a close relationship between histomorphometric and functional findings. © 2009 Wiley‐Liss, Inc. Microsurgery, 2009.
Global weak solution to the flow of liquid crystals system
Authors: Jiang Fei , Tan Zhong 
Published: April 2009

AbstractIn this paper, we study a simplified system for the flow of nematic liquid crystals in a bounded domain in the three‐dimensional space. We derive the basic energy law which enables us to prove the global existence of the weak solutions under the condition that the initial density belongs to Lγ(Ω) for any \documentclass{article}\footskip=0pc\pagestyle{empty}\begin{document}$\gamma >\frac{3}{2}$\end{document}. Especially, we also obtain that the weak solutions satisfy the energy inequality in integral or differential form. Copyright © 2009 John Wiley & Sons, Ltd.