bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue Engineering
Authors: Burg Karen , Thomas Chuck 
Published: April 2006

Abstract
Tissue engineering is a field of bioengineering that merges fundamentals of medicine, engineering, biological science, and materials science to research and produce replacement tissues or organs. In this article, the basics of tissue engineering are discussed, including the different types of cells and matrices researched and how these components are used separately or together for tissue‐engineering applications. After the principles of tissue engineering are described, the role of tissue engineering in medicine is explored with separate discussions on dermal wound treatment, orthopedics, sports medicine, plastic and reconstructive surgery, neurology, and cardiology. Then, the current status of tissue engineering is investigated, from market products to advanced research and manufacturing applications. The article concludes with an exploration of scientific, regulatory, and commercial challenges that must be overcome in order to advance the field of tissue engineering.
Tissue‐Engineered Bone
Authors: Cui Fu-Zhai , Jiang Teng-Fei 
Published: April 2006

Abstract
Tissue‐engineered bone is a bone tissue regenerated based on the principle of tissue engineering. It can restore the structure and function of a bone defect by using the healing response of vertebrates’ body. Bone cells, bone growth factors, and biodegradable scaffolds are the three elements in bone tissue engineering. By combining one or more of these elements, successful bone defect treatments have been achieved using tissue‐engineered bone.
Three‐dimensional CFD model of the deaeration rate of FCC particles
Authors: Das Sharma Sanjib , Pugsley Todd , Delatour Romain 
Published: April 2006

AbstractComputational fluid dynamics (CFD) has been used to model the deaeration rate for a fluidized bed of fluid catalytic cracking (FCC) catalyst. The Eulerian approach has been used in which the gas and solid phases present in the fluidized bed are treated as interpenetrating continua with constitutive equations obtained from the granular kinetic theory and the interphase drag relationship. Using the CFD code MFIX, transient calculations have been made for a three‐dimensional (3‐D) cylindrical vessel of 0.104 m diameter. Various cases have been modeled: fluidization at superficial gas velocities of 0.005 and 0.028 m/s followed by deaeration for two catalyst bed masses of 3.17 and 4.05 kg. These have been performed for monosize particles of Sauter mean diameters of 69.8 and 100 microns. The results have been presented in terms of variation of gauge pressure with time at a height of 30 cm above the distributor plate. Comparisons of these predictions with the experimental data show that the deviation between the experimental results and the CFD predictions of deaeration rate is <10%. Based on these results it appears that our CFD modeling approach, which includes the introduction of an empirical correction factor for the gas–solid drag term, can adequately predict the deaeration rate of FCC catalyst using a single mean particle size. © 2006 American Institute of Chemical Engineers AIChE J, 2006
Isovaleric acidemia: New aspects of genetic and phenotypic heterogeneity
Authors: Vockley Jerry , Ensenauer Regina 
Published: April 2006

AbstractIsovaleric acidemia (IVA) is an autosomal recessive inborn error of leucine metabolism caused by a deficiency of the mitochondrial enzyme isovaleryl‐CoA dehydrogenase (IVD) resulting in the accumulation of derivatives of isovaleryl‐CoA. It was the first organic acidemia recognized in humans and can cause significant morbidity and mortality. Early diagnosis and treatment with a protein restricted diet and supplementation with carnitine and glycine are effective in promoting normal development in severely affected individuals. Both intra‐ and interfamilial variability have been recognized. Initially, two phenotypes with either an acute neonatal or a chronic intermittent presentation were described. More recently, a third group of individuals with mild biochemical abnormalities who can be asymptomatic have been identified through newborn screening of blood spots by tandem mass spectrometry. IVD is a flavoenzyme that catalyzes the conversion of isovaleryl‐CoA to 3‐methylcrotonyl‐CoA and transfers electrons to the electron transfer flavoprotein. Human IVD has been purified from tissue and recombinant sources and its biochemical and physical properties have been extensively studied. Molecular analysis of the IVD gene from patients with IVA has allowed characterization of different types of mutations in this gene. One missense mutation, 932C>T (A282V), is particularly common in patients identified through newborn screening with mild metabolite elevations and who have remained asymptomatic to date. This mutation leads to a partially active enzyme with altered catalytic properties; however, its effects on clinical outcome and the necessity of therapy are still unknown. A better understanding of the heterogeneity of this disease and the relevance of genotype/phenotype correlations to clinical management of patients are among the challenges remaining in the study of this disorder in the coming years. © 2006 Wiley‐Liss, Inc.
Modification of chitosan towards a biomaterial with improved physico‐chemical properties
Authors: Mallika P. , Himabindu A. , Shailaja D. 
Published: April 2006

AbstractModification of chitosan (CTN), a natural biomaterial, leading to improved physical and chemical properties makes the polymer overcome the limitations on its application in biomedical fields. We have modified CTN using polyvinylpyrrolidone (PVP) in three ways, i.e., by blending (CTN : PVP), by graft copolymerization [poly(CTN‐g‐PVP)], and by free radical induced crosslinking [poly(CTN‐cl‐PVP)], varying the CTN to PVP ratio. The properties of all the modified and unmodified CTN studied included structural, thermal, mechanical, and water uptake capacity. Modification by blending imparted enhanced strength, toughness, glass transition temperatures, and thermal stability to the dry membranes. The equilibrium water content (EWC) of the membrane gels was investigated as a function of pH and ionic strength. Swelling ratio of the chemically modified membranes were found to be less sensitive to pH, with higher % EWC maintaining the gel integrity in both acidic and neutral media unlike the plain CTN. The hydrogen bonding and free volume of the films were found to play a major role in determining the properties of the type of modification. CTN membranes with enhanced water uptake capacities clubbed with optimum mechanical properties shall be a suitable choice for biomedical and controlled release applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 63–69, 2006
Synthesis and characterization of copolyarylates using tin octoate as a catalyst
Authors: Waghmare P. B. , Pathak P. , Deshmukh S. A. , Idage S. B. , Idage B. B. 
Published: April 2006

AbstractA series of copolyarylates of bisphenol A (BPA) with varying ratios of diphenyl terephthalate (DPT) and diphenyl isophthalate (DPI) were prepared by melt polymerization at a temperature ranging from 200 to 290°C under reduced pressure in the presence of tin octoate catalyst. Tin octoate catalyst has been extensively used for the preparation of biodegradable polymers namely, poly(lactic acid), poly(glycolic acid), and poly(lactide‐glycolide) copolyesters. However, there are no reports on the preparation of copolyesters by melt polymerization using tin octoate catalyst. The effect of tin octoate catalyst was studied on the preparation of BPA/DPT/DPI copolyarylates. The copolyarylates were characterized by infrared and 1H NMR spectroscopy, solution viscosity, thermogravimetric analysis, differential scanning calorimetry, and X‐ray diffraction. The solution viscosities of copolyarylates were varied from 0.43 to 0.56 dL/g and the glass transition temperature (Tg) of copolyarylates was varied from 155 to 222°C by varying the ratio of DPT and DPI. Most of the copolyarylates were found to be soluble in commonly used organic solvents and had film‐forming properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 70–77, 2006
Maghnite‐H+ as a cationic catalyst in the synthesis of poly(1,3‐dioxolane) and α,ω‐methacryloyloxy‐poly(1,3‐dioxolane)
Authors: Megherbi Radja , Belbachir Mohammed , Meghabar Rachid 
Published: April 2006

AbstractThe polymerization of 1,3‐dioxolane catalyzed by Maghnite‐H+; (Mag‐H+), a montmorillonite sheet silicate clay exchanged with protons, was investigated. The cationic ring‐opening polymerization of 1,3‐dioxolane was initiated by Mag‐H+ at different temperatures (20, 30, 50, and 70°C) in bulk and in a solvent (dichloromethane). The effects of the amount of Mag‐H+ and the temperature were studied. The polymerization rate and the average molecular weights increased with an increase in the temperature and the proportion of the catalyst. These results indicated the cationic nature of the polymerization and suggested that the polymerization was initiated by proton addition to the monomer from Mag‐H+. Moreover, we used a simple method, in one step in bulk and in solution at room temperature (20°C), to prepare a telechelic bismacromonomer: α,ω‐bisunsaturated poly(1,3‐dioxolane). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 78–82, 2006
An electromagnetic dynamic film blowing technology for mLLDPE
Authors: Zhou Nan‐Qiao , Zhang Ping , Wu Hong‐Wu , Peng Xiang‐Fang 
Published: April 2006

AbstractMetallocene linear low‐density polyethylene (mLLDPE) has superior physical and mechanical properties. However, mLLDPE has very poor film blowing processibility. To overcome this shortcoming, an electromagnetic dynamic extruding film blowing system for mLLDPE was developed. A vibration force field was superposed on the entire extruding process through the screw. The die pressure, the screw load, and the power consumption decreased and the melt strength increased as the vibration frequency and amplitude increased, implying that the bubble stability enhanced, which resulted in the improvement of the processibility. In addition, experimental data show that the film strength in the transverse direction greatly increased and the film mechanical properties in machine and transverse directions became more uniform, so the film quality was improved finally. This rule was confirmed by using two additional materials, high‐density polyethylene and low‐density polyethylene. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 83–89, 2006
On relevance distributions
Authors: Stock Wolfgang G. 
Published: April 2006

AbstractThere are at least three possible ways that documents are distributed by relevance: informetric (power law), inverse logistic, and dichotomous. The nature of the type of distribution has implications for the construction of relevance ranking algorithms for search engines, for automated (blind) relevance feedback, for user behavior when using Web search engines, for combining of outputs of search engines for metasearch, for topic detection and tracking, and for the methodology of evaluation of information retrieval systems.
The Bayesian method of moments (BMOM) in some aggregation problems in econometrics
Authors: de Alba Enrique 
Published: April 2006

AbstractThe BMOM is particularly useful for obtaining post‐data moments and densities for parameters and future observations when the form of the likelihood function is unknown and thus a traditional Bayesian approach cannot be used. Also, even when the form of the likelihood is assumed known, in time series problems it is sometimes difficult to formulate an appropriate prior density. Here, we show how the BMOM approach can be used in two, nontraditional problems. The first one is conditional forecasting in regression and time series autoregressive models. Specifically, it is shown that when forecasting disaggregated data (say quarterly data) and given aggregate constraints (say in terms of annual data) it is possible to apply a Bayesian approach to derive conditional forecasts in the multiple regression model. The types of constraints (conditioning) usually considered are that the sum, or the average, of the forecasts equals a given value. This kind of condition can be applied to forecasting quarterly values whose sum must be equal to a given annual value. Analogous results are obtained for AR(p) models. The second problem we analyse is the issue of aggregation and disaggregation of data in relation to predictive precision and modelling. Predictive densities are derived for future aggregate values by means of the BMOM based on a model for disaggregated data. They are then compared with those derived based on aggregated data. Copyright © 2006 John Wiley & Sons, Ltd.
Bayesian geo‐additive modelling of childhood morbidity in Malawi
Authors: Kandala Ngianga‐Bakwin 
Published: April 2006

AbstractThis paper applies a geo‐additive generalized linear mixed model to describe the spatial variation in the prevalence of cough among children under 5 years of age using the 2000 Demographic and Health survey (DHS) data from Malawi. Of particular interest in the analysis were the small area effect of geographical locations (districts) where the child lives in the time of the survey and the effect of the metrical covariate (child's age) which was assumed to be nonlinear and estimated nonparametrically. The model included other categorical covariates in the usual parametric form. We assign appropriate priors, within a Bayesian context, for the geographical location, vector of the unknown nonlinear smooth functions and a further vector of fixed effect parameters. For example, the spatial effects were modelled via Bayesian prior specifications reflecting spatial heterogeneity globally and relative homogeneity among neighbouring districts, thus a Markov random field prior is assumed. Inference is fully Bayesian and uses recent Markov chain Monte Carlo techniques. Copyright © 2006 John Wiley & Sons, Ltd.
On Bayesian forecasting of procurement delays: a case study
Authors: Palomo Jesus , Ruggeri Fabrizio , Rios Insua David , Cagno Enrico , Caron Franco , Mancini Mauro 
Published: April 2006

AbstractIn the engineering and contracting sector, the on‐time availability of materials is a crucial element of any project. In recent years, there has been increasing competition in the supply of such components, as a result of market globalization. This has generated customer demand for higher performance, service, and quality—and, most of all, shorter delivery times. However, it has also forced suppliers to increase efforts to satisfy these requirements in order to remain competitive. Thus, contractors have moved to focus their attention on the task of more precisely modelling on‐time delivery risks. Historical data, expert opinion, and agreements between contractors and suppliers are some available sources of information that can be used to generate more accurate forecasts. We combine these various inputs in a Bayesian approach based on dynamic linear modelling. Our methodology has been implemented as a web‐based Decision Support System, and has been applied in a real case study from an oil sector engineering and contracting company. Copyright © 2006 John Wiley & Sons, Ltd.
Copula models of joint last survivor analysis
Authors: E. Shemyakin Arkady , Youn Heekyung 
Published: April 2006

AbstractCopula models are becoming increasingly popular for modelling dependencies between random variables. The range of their recent applications includes such fields as analysis of extremes in financial assets and returns; failure of paired organs in health science; reliability studies; and human mortality in insurance.This paper gives a brief overview of the principles of construction of such copula models as Gaussian, Student, and Archimedean. The latter includes Frank, Clayton, and stable (Gumbel–Hougaard) families. The emphasis is on application of copula models to joint last survivor analysis.The main example discussed in this paper deals with the mortality of spouses, known to be associated through such factors as common disaster, common lifestyle, or the broken‐heart syndrome. These factors suggest modelling dependence of spouses' lives on both calendar date scale and age‐at‐death scale. This dependence structure suggests a different treatment than that for problems of survival analysis such as paired organ failure or twins' mortality.Construction of a conditional Bayesian copula model is further generalized in view of the relationship between the joint first life and last surviror probabilities. A numerical example is considered, involving the implementation of Markov chain Monte Carlo algorithms using WinBUGs. Copyright © 2006 John Wiley & Sons, Ltd.
Development and calibration of a nitrification PDE model based on experimental data issued from biofilter treating drinking water
Authors: Queinnec I. , Ochoa J.C. , Wouwer A. Vande , Paul E. 
Published: April 2006

AbstractTo remove ammonia for production of drinking water, nitrification can be performed in a bio‐filter. At least 1 month is necessary to capture from the groundwater and then grow a sufficient amount of nitrifying bacteria to reach the desired removal efficiency. Improving start‐up of bio‐filters at low substrate concentration is therefore a major challenge. In this connection, it is important to develop appropriate models for designing, monitoring or analysing biofilm systems during start‐up or following disinfection events. This study discusses the development and calibration of a nitrification PDE model which reflects the compromise between the complexity associated with the description of the full physical and biochemical mechanisms and the search for a simplified model with identifiable parameters. This model takes only the relevant phenomena (considering the full operating range) into account. The validity of the calibrated model has been evaluated through experiments under very different operational conditions, at the laboratory and under real industrial conditions, involving the full upstream chain of water treatment (iron oxidation and sand filter). © 2006 Wiley Periodicals, Inc.
Determination of the decay rate of nitrifying bacteria
Authors: Salem S. , Moussa M.S. , van Loosdrecht M.C.M. 
Published: April 2006

AbstractThe growth and decay of nitrifying organisms determines the amount of nitrifying bacteria in activated sludge systems. The growth rate of the nitrifying organisms is reasonable, well defined, and studied, while the decay rate is still rather uncertain. Experiments in previous studies were over periods up to 14 days and obtained results were not confirmed. Contradicting decay rates of nitrifiers in different bacterial communities is reported. No differentiation between ammonia and nitrite oxidizers was made. Therefore, in this studyper day the decay rate of the nitrifying organisms was studied. The starvation condition (aerobic, anoxic, or anaerobic), temperature, type of bacterial community, and the presence of higher organisms are the main aspects that were investigated. A simple and reliable method (adapted from previous studies) for determining the decay rate of nitrifying organisms under different starvation conditions and different temperatures was developed. The test procedure has been used for determining the decay rate of ammonium and nitrite oxidizing bacteria in an enriched nitrifying culture and in activated sludge. The test was successfully applied at starvation periods up to 30 days. The decay rate of the enriched culture of nitrifiers was very low compared to values for nitrifiers in activated sludge. The decay rate of the nitrifiers in activated sludge was found to be to 0.2, 0.1, and 0.06 per day for aerobic, anoxic, and anaerobic conditions, respectively. The decay rate of ammonia oxidizers and nitrite oxidizers was the same at the corresponding conditions. © 2006 Wiley Periodicals, Inc.
Diffusivity of oxygen in aerobic granules
Authors: Chiu Z.C. , Chen M.Y. , Lee D.J. , Tay S.T.‐L. , Tay J.H. , Show K.Y. 
Published: April 2006

AbstractThis work for the first time estimated apparent oxygen diffusivity (Dapp) of two types of aerobic granules, acetate‐fed and phenol‐fed, by probing the dissolved oxygen (DO) level at the granule center with a sudden change in the DO of the bulk liquid. With a high enough flow velocity across the granule to minimize the effects of external mass transfer resistance, the diffusivity coefficients of the two types of granules were estimated with reference to a one‐dimensional diffusion model. The carbon source has a considerable effect on the granule diameter (d) and the oxygen diffusivity. The diffusivity coefficients were noted 1.24–2.28 × 10−9 m2/s of 1.28–2.50 mm acetate‐fed granules, and 2.50–7.65 × 10−10 m2/s of 0.42–0.78 mm phenol‐fed granules. Oxygen diffusivity declined with decreasing granule diameter, in particular, the diffusivity of acetate‐fed granules is proportional to the size, whereas the diffusivity of phenol‐fed granules is proportional to the square of granule diameter. The existence of large pores in granule, evidenced by FISH‐CLSM imaging, was proposed to correspond to the noted size‐dependent oxygen diffusivity. The phenol‐fed granules exhibited a higher excellular polymer (ECP) content than the acetate‐fed granules, hence yielding a lower oxygen diffusivity. © 2006 Wiley Periodicals, Inc.
Combining caspase and mitochondrial dysfunction inhibitors of apoptosis to limit cell death in mammalian cell cultures
Authors: Sauerwald Tina M. , Figueroa Bruno , Hardwick J. Marie , Oyler George A. , Betenbaugh Michael J. 
Published: April 2006

AbstractApoptosis is now recognized as a significant problem in mammalian cell culture. Therefore, in this study, a single gene and multigene approach to inhibit apoptosis has been examined. Stable Chinese hamster ovary (CHO) cell lines were generated to overexpress different single, dual, and triple combinations of three apoptosis inhibitor genes. Two upstream inhibitors involved in the mitochondrial pathway, Bcl‐XL and Aven, were expressed in addition to a downstream inhibitor of caspases. The caspase inhibitor, a variant of XIAP containing only the caspase inhibitory BIR domains (XIAP‐BIRs), has been shown previously to enhance viabilities in mammalian cultures. Stable clonal cell lines were generated and tested for three apoptotic insults: Sindbis virus infection, the chemical reagent etoposide, and spent medium. For all single gene experiments, the Bcl‐XL‐containing cell lines provided superior protection to either the Aven‐ or XIAP‐BIRs‐containing cell lines following initial exposure to the insults. However, the cell lines expressing two or more anti‐apoptosis proteins were more effective at inhibiting cell death than those expressing just one anti‐apoptosis gene. The cell lines overexpressing Bcl‐XL in combination with XIAP‐BIRs were especially effective in delaying cell death for all three apoptotic insults. Expression of all three anti‐apoptosis genes in concert was only slightly more effective than using Bcl‐XL and XIAP‐BIRs for some insults. During exposure to spent medium, CHO‐BIRS + Aven + BclXL was the best inhibitor of apoptosis (IAP) initially, whereas CHO‐BIRs + BclXL was particularly effective at later times of the experiment. In conclusion, the utilization of a mitochondrial dysfunction inhibitor used in combination with a caspase inhibitor was more effective in thwarting the progression of apoptosis than either inhibitor expressed individually. Thus, the concurrent expression of multiple apoptosis inhibitors may be the most effective strategy to increase survival of mammalian cells in culture. © 2006 Wiley Periodicals, Inc.