bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency of extreme rainfall events in Southern Brazil modulated by interannual and interdecadal variability
Authors: Pscheidt Ieda , Grimm Alice Marlene
Published: December 2008

The frequency of extreme rainfall events in Southern Brazil is impacted by El Niño—Southern Oscillation (ENSO) episodes, especially in austral spring. There are two areas in which this impact is more significant: one is on the coast, where extreme events are more frequent during El Niño (EN) and the other one extends inland, where extreme events increase during EN and decrease during La Niña (LN). Atmospheric circulation patterns associated with severe rainfall in those areas are similar (opposite) to anomalous patterns characteristic of EN (LN) episodes, indicating why increase (decrease) of extreme events in EN (LN) episodes is favoured. The most recurrent precipitation patterns during extreme rainfall events in each of these areas are disclosed by Principal Component Analysis (PCA) and evidence the separation between extreme events in these areas: a severe precipitation event generally does not occur simultaneously in the coast and inland, although they may occur inland and in the coastal region in sequence. Although EN predominantly enhances extreme rainfall, there are EN years in which fewer severe events occur than the average of neutral years, and also the enhancement of extreme rainfall is not uniform for different EN episodes, because the interdecadal non‐ENSO variability also modulates significantly the frequency of extreme events in Southern Brazil. The inland region, which is more affected, shows increase (decrease) of extreme rainfall in association with the negative (positive) phase of the Atlantic Multidecadal Variability, with the negative (positive) phase of the Pacific Multidecadal Variability and with the positive (negative) phase of the Pacific Interdecadal Variability. Copyright © 2008 Royal Meteorological Society
The annual cycle of heavy precipitation across the United Kingdom: a model based on extreme value statistics
Authors: Maraun D. , Rust H. W. , Osborn T. J.
Published: December 2008

The annual cycle of extreme 1‐day precipitation events across the UK is investigated by developing a statistical model and fitting it to data from 689 rain gauges. A generalized extreme‐value distribution (GEV) is fit to the time series of monthly maxima, across all months of the year simultaneously, by approximating the annual cycles of the location and scale parameters by harmonic functions, while keeping the shape parameter constant throughout the year. We average the shape parameter of neighbouring rain gauges to decrease parameter uncertainties, and also interpolate values of all model parameters to give complete coverage of the UK. The model reveals distinct spatial patterns for the estimated parameters. The annual mean of the location and scale parameter is highly correlated with orography. The annual cycle of the location parameter is strong in the northwest UK (peaking in late autumn or winter) and in East Anglia (where it peaks in late summer), and low in the Midlands. The annual cycle of the scale parameter exhibits a similar pattern with strongest amplitudes in East Anglia. The spatial patterns of the annual cycle phase suggest that they are linked to the dominance of frontal precipitation for generating extreme precipitation in the west and convective precipitation in the southeast of the UK. The shape parameter shows a gradient from positive values in the east to negative values in some areas of the west. We also estimate 10‐year and 100‐year return levels at each rain gauge, and interpolated across the UK. Copyright © 2008 Royal Meteorological Society
Homogenization of Bulgarian temperature series
Authors: Syrakova Margarita , Stefanova Milena
Published: December 2008

The Standard Normal Homogeneity Test (SNHT) was applied to five sets of temperature series—the four seasonal and the annual mean temperatures, at stations representative for the lowlands of Bulgaria. Series cover periods of about 50 to about 100 years. Fourteen percent of the series passed the test successfully, the others had one or more breaks. The number of breaks in the cold seasons was less than the number of breaks in the warm seasons. On average, 38% of the breaks could not be explained by the stations' history, the percentage being the greatest (almost 50%) for the summer series. The adjustments were in the range (−1.2, 0.9)°C. The average values were negative (about − 0.1 °C) for the winter, spring and summer series, but for the autumn and annual series they were practically zero. The average absolute values for different seasons were between 0.34 and 0.44 °C. Magnitudes of the adjustments were greater in the regions closer to the mountains than in the more flat areas. Most of the inhomogeneities were caused by station relocations. Copyright © 2008 Royal Meteorological Society
Space and time behavior of climatic hazard of low temperature for single rice crop in the mid latitude
Authors: Mariani Luigi , Parisi Simone Gabriele , Cola Gabriele
Published: December 2008

Rice is a crop of tropical origin and therefore very sensitive to low temperatures, particularly during the crucial phase of floral differentiation. A World survey on climatic hazard of low temperatures during this phase was carried out on the basis of National Centers for Environmental Prediction (NCEP) reanalysis temperature data at 850 hPa. The spatial behavior of risk in analysed areas shows high risk for Australia, moderate one for Europe, South America and East Asia, whereas a very low or null risk is shown for North Africa, South Brazil, Iran, Korea and Louisiana.

Results show that the level of risk for many regions of the Boreal hemisphere is substantially lowered after the breakpoint of 1981, whereas a more stable situation of risk is observed in the Austral one and particularly in Australia. A global map of risk was also produced and possible limitations of the selected approach are finally discussed. Copyright © 2008 Royal Meteorological Society
Multilayer tendon slices seeded with bone marrow stromal cells: A novel composite for tendon engineering
Authors: Omae Hiromichi , Zhao Chunfeng , Sun Yu Long , An Kai‐Nan , Amadio Peter C.
Published: December 2008

The ideal scaffold for tendon engineering would possess the basic structure of the tendon, native extracellular matrix, and capability of cell seeding. The purpose of this study was to assess the tissue engineering potential of a novel composite consisting of a decellularized multilayer sliced tendon (MST) scaffold seeded with bone marrow stromal cells (BMSC). BMSC and infraspinatus tendons were harvested from 20 dogs. The tendons were sectioned in longitudinal slices with a thickness of 50 µm. The slices were decellularized, seeded with BMSC, and then bundled into one composite. The composite was incubated in culture media for 14 days. The resulting BMSC‐seeded MST was evaluated by qRT‐PCR and histology. The BMSC viability was assessed by a fluorescent tracking marker. Histology showed that the seeded cells aligned between the collagen fibers of the tendon slices. Analysis by qRT‐PCR showed higher tenomodulin and MMP13 expression and lower collagen type I expression in the composite than in the BMSC before seeding. BMSC labeled with fluorescent tracking marker were observed in the composite after culture. Mechanical testing showed no differences between scaffolds with or without BMSC. BMSC can survive in a MST scaffold. The increased tenomodulin expression suggests that BMSC might express a tendon phenotype in this environment. This new composite might be useful as a model of tendon tissue engineering. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 937–942, 2009
Preparation of chelating fibrous polymer by different diamines and study on their physical and chemical properties
Authors: Tahaei P. , Abdouss M. , Edrissi M. , Shoushtari A. M. , Zargaran M.
Published: December 2008

The present work describes a new modification process for producing a chelating ion‐exchanger fibers with a distinct selectivity for toxic heavy metal ions. Acrylic fibers were reacted with different diamine compounds in similar conditions. Modified acrylic fibers were prepared by partial conversion of the nitrile groups into amino groups under two‐step processes. In the first step, the pure liquid diamine was mixed with the fibers and in the second step, water was gradually added to the reaction flask to reach a predetermined 3M concentration at refluxing temperature of 91 °C. The aminated acrylic fibers (AAFs) were used as an ion adsorbent in a series of batch adsorption experiments for removal of chromium(III) and lead (II) ions.

Experimental results showed that modified acrylic fiber with tetra methylene diamine (TMD) has the highest Pb(II) ion adsorption capacity. Results also showed aminated acrylic with ethylene diamine (EDA) has the most Cr(III) ion adsorption ability. Solubility tests showed, amination treatments give rise to the intermolecular crosslinkage in all samples. The Freundlich and Langmuir models simulated the adsorption equilibrium data of Cr(III) ions on modified fibers and their constants were determined.
Nanophase hardfaced coatings
Authors: Reisgen U. , Stein L. , Balashov B. , Geffers C.
Published: December 2008

This paper demonstrates the possibility of producing iron‐ or chromium‐based nanophase hardfaced coatings by means of common arc welding methods (TIG, PTA). The appropriate composition of the alloys to be deposited allows to control the structural properties and thus also the coating properties of the weld metal. Specific variations of the alloying elements allow also the realisation of a nanostructured solidification of the carbides and borides with cooling rates that are common for arc surfacing processes. The hardfaced coatings, which had been thus produced, showed phase dimensions of approximately 100–300 nm. Based on the results it is established that the influence of the surfacing parameters and of the coating thickness and thus the influence of the heat control on the nanostructuring process is, compared with the influence of the alloy composition, of secondary importance. The generation of nanoscale structures in hardfaced coatings allows the improvement of mechanical properties, wear resistance and corrosion resistance. Potential applications for these types of hardfaced coatings lie, in particular, in the field of cutting tools that are exposed to corrosion and wear.
Mechanical properties of co‐extruded wear resistant powder metallurgical layers on steel substrates
Authors: Röttger A. , Karlsohn M. , Theisen W. , Silva P. , Weber S. , Pyzalla A.
Published: December 2008

Materials with high resistance against abrasive wear are of interest for many tool applications. For economical reasons, thick coatings of several millimetres are requested. The cladding of these materials to low alloyed substrates is commonly performed using hot isostatic pressing, being a cost intensive process in particular for long products. Thus, a novel manufacturing route via direct hot extrusion of encapsulated bulk steel bars and presintered tool steel powders was recently developed. In this manner, wear resistant claddings of PM tool steels and wear resistant MMC on steel substrates could be processed.

Heating to process temperature leads to presintering of the powder and only a weak bonding between the steel substrate and the powdery layer. However, after direct hot extrusion at 1150 °C an interface free of macroscopic defects is formed between both materials. The quality and strength of this bond zone was investigated by micro tensile, 4 point bending and shear tests for different materials combinations. For high strength substrate materials, failure always occurs in the brittle wear resistant layer and not at the interface. These results are in agreement with microstructural investigations, exhibiting a pore‐ and defect‐free interface dominated by interdiffusion processes.
Modell zur Analyse des knöchernen Anwachsverhaltens auf bioaktiv beschichteten Implantatoberflächen
Authors: Lochner K. , Erdmann C. , Lüdtke B. , Hansmann D. , Fulda G. , Labs W. , Neumann H.‐G. , Mittelmeier W. , Bader R.
Published: December 2008

Auf dem Gebiet der Knochenregeneration sind transiente und permanente Implantate eine wichtige Therapiesäule in der Orthopädischen Chirurgie. In diesem Zusammenhang sind bioaktive Oberflächen von metallischen Implantaten von besonderer Bedeutung. In der vorliegenden Studie sollte ein In‐vitro‐Testsystem etabliert werden, mit dessen Hilfe die Qualität solcher Oberflächen im Hinblick auf Anwachsen und Besiedelung mit Knochenzellen untersucht werden kann. Dazu wurden speziell gefertigte Klammern aus Reintitan (cp‐Ti) mit verschiedenen bioaktiven Oberflächen (BONIT‐HA®, BONIT®) ausgestattet: In diese Klammern wurden jeweils Spongiosazylinder von definierter Größe eingespannt und das Auswachsverhalten von osteoblasten‐ähnlichen Zellen unter Zellkulturbedingungen beobachtet. Nach 10 Inkubationstagen wurde mittels Rasterelektronenmikroskop (REM) die Ausbreitung der aus der Spongiosa abgeleiteten Zellen beurteilt. Es wurde eine gleichmäßige Besiedelung der BONIT® und BONIT‐HA® beschichteten Flächen festgestellt, im Gegensatz zu HA‐gestrahlten Klammern ohne zusätzliche, elektrochemische Beschichtung (Referenz). Diese Ergebnisse zeigen, dass sich das neu entwickelte In‐vitro‐Testsystem mit humaner Spongiosa eignet, um die Oberflächenbeschaffenheit medizinischer Implantate in Bezug auf die Besiedelung durch osteoblasten‐ähnliche Zellen reproduzierbar qualitativ zu charakterisieren.
On the 4JHH long‐range coupling in 2‐bromocyclohexanone: conformational insights
Authors: Coelho Jakelyne V. , Freitas Matheus P. , Tormena Cláudio F. , Rittner Roberto
Published: December 2008

2‐Bromocyclohexanone is a model compound in which a 4JH2, H6 coupling constant is observed, whereas the corresponding 4JH2, H4 is absent. The observed long‐range coupling is not only a result of the known W‐type coupling, in the axial conformation, but also because of the less usual diaxial spin–spin coupling in the equatorial conformer. The carbonyl group plays a determining role in describing the coupling pathway, as concluded by natural bond orbital (NBO) analysis; although the $\sigma _{{\rm C2 - H2}} \rightarrow \sigma \ast_{{\rm C1(O) - C6}}$ and $\sigma_{{\rm C6 - H6}} \rightarrow \sigma \ast_{{\rm C1(O) - C2}}$ interactions in the axial conformer contribute for transmitting the spin information associated with the W‐type coupling, the strong $\sigma_{{\rm C2 - H2}} \rightarrow \pi \ast_{{\rm C = O}}$ and $\sigma_{{\rm C6 - H6}} \rightarrow \pi \ast_{{\rm C = O}}$ hyperconjugations in the equatorial conformer define an enhanced coupling pathway for 4JH2, H6, despite the inhibition of this coupling because of $n_{{\rm O}} \rightarrow \sigma \ast_{{\rm C(O) - C}}$ interaction and the large carbonyl angle. These findings provide the experimental evidence that orbital interactions contribute for the conformational isomerism of 2‐bromocyclohexanone. Copyright © 2008 John Wiley & Sons, Ltd.
Urodynamic findings and functional or anatomical obstructions in children who developed bladder diverticula after reimplantation of the ureter
Authors: Martijn Tilanus , Aart Klijn , Pieter Dik , Laetitia de Kort , Tom de Jong
Published: December 2008

Objective

To study the clinical and urodynamic parameters of children who developed bladder diverticula (BD) after ureteral reimplantation.

Materials and methods

We have reviewed records of 15 children who underwent ureteric reimplantation, possibly with diverticulectomy between January 1998 and October 2004, who postoperatively developed BD and compared the results with 25 patients, surgically treated for primary vesicoureteric reflux (VUR) without BD development after reimplantation. A total of 737 reimplantations was performed in 492 patients. Of the 15 patients and 25 controls we reviewed voiding history and free uroflowmetry, urodynamic parameters, findings on urethrocystoscopy, VCUG and signs of dysfunctional or anatomical obstruction.

Results

Of the fifteen patients with a postoperative diverticulum, one patient (7%) had an infravesical obstruction in combination with a normal voiding pattern, nine patients (60%) had severe dysfunctional voiding and two patients (13%) had both. Three patients had no infravesical obstruction nor dysfunctional voiding. Urodynamically the mean Pmax postoperatively was 96.8 (cm‐H2O) in the obstructed patients (BD‐group) (in controls 50.0 cm‐H2O) and 95.6 (cm‐H2O) for the dysfunctional voiders (in controls 61.8 cm‐H2O). The difference between the Pmax values of BD‐group and controls was significant on the 95% C.I. (P < 0.01).

Conclusion

Dysfunctional voiding and infravesical obstruction in children appear to be important risk factors for acquired BD. Voiding pressures are significantly higher in patients that developed BD. Cognitive bladder training to normalize voiding pressures should be done before surgery if feasible. Special attention should be paid to the persistence of an infravesical obstruction. Neurourol. Urodynam. 28:241–245, 2009. © 2008 Wiley‐Liss, Inc.
Quality control in urodynamics: Analysis of an international multi‐center study
Authors: Renganathan Arasee , Cartwright Rufus , Cardozo Linda , Robinson Dudley , Srikrishna Sushma
Published: December 2008

Aims

To review the quality of urodynamic traces collected as part of a multi‐center Phase II drug trial of a medication for overactive bladder (OAB), in order to assess adherence to the Good Urodynamic Practice (GUP) guidelines. To assess inter‐rater reliability (IRR) for the numerical cystometrogram variables, and for the diagnosis of detrusor overactivity (DO).

Methods

Two central reviewers assessed 50 cystometrograms, recording the presence or absence of DO and assessing compliance with GUP guidelines. Three central reviewers independently assessed 20% of cystometrograms submitted, for numerical variables. IRR of central and peripheral assessments were compared with intra‐class correlation (ICC) and Cohen's unweighted kappa statistics.

Results

There was inconsistent adherence to GUP guidelines, because of differences in urodynamic equipment and practice. ICC between numerical variables assessed by the three central reviewers were excellent ranging between 0.830 and 0.997 (P all ≤0.001). ICC between numerical variables assessed by peripheral and central reviewers were good to excellent, ranging between 0.624 and 0.994 (P all ≤0.05). Central reviewers showed excellent agreement in the assessment of DO (kappa = 0.83). However central and peripheral reviewers showed poor agreement in the assessment of DO (kappa = 0.24).

Conclusion

Without standardization of equipment and training, adherence to GUP guidelines is problematic. Cystometric pressure and volume variables can however be reliably assessed in multi‐center studies. DO cannot be reliably observed by interpreting the cystometrogram trace in isolation. Objective assessment of DO may therefore be unsuitable for multi‐center studies reliant on central reporting of traces. Neurourol. Urodynam. 28:380–384, 2009. © 2008 Wiley‐Liss, Inc.
Competition under time‐varying demands and dynamic lot sizing costs
Authors: Federgruen Awi , Meissner Joern
Published: December 2008

We develop a competitive pricing model which combines the complexity of time‐varying demand and cost functions and that of scale economies arising from dynamic lot sizing costs. Each firm can replenish inventory in each of the T periods into which the planning horizon is partitioned. Fixed as well as variable procurement costs are incurred for each procurement order, along with inventory carrying costs. Each firm adopts, at the beginning of the planning horizon, a (single) price to be employed throughout the horizon. On the basis of each period's system of demand equations, these prices determine a time series of demands for each firm, which needs to service them with an optimal corresponding dynamic lot sizing plan. We establish the existence of a price equilibrium and associated optimal dynamic lotsizing plans, under mild conditions. We also design efficient procedures to compute the equilibrium prices and dynamic lotsizing plans.© 2008 Wiley Periodicals, Inc. Naval Research Logistics 2009
Optimal design of accelerated life testing plans for periodical replacement with penalty
Authors: Liao Haitao
Published: December 2008

Accelerated life testing (ALT), enhanced by optimal test plans, has been widely accepted in practice as a quick approach for estimating the reliability of a product. From the estimation result, preventive maintenance schedules can be determined to ensure the performance of the product under its normal operating conditions. By default, maintenance decision‐making is regarded as the last and least rewarding step. However, sometimes the maintenance schedules, such as preventive maintenance intervals, are predetermined due to customer concerns and/or by various mandatory regulations and rules. Under such circumstances, how to accurately estimate the expenditure (e.g., on maintenance or spare parts management) associated with these maintenance requirements becomes an important issue. A viable solution is to incorporate the maintenance requirements into ALT plans. This paper provides an approach for the optimal design of ALT plans oriented by a mandatory periodical replacement schedule subject to a discounted penalty. The objective is to improve the estimation accuracy of the economic impact of this maintenance requirement. A numerical experiment is provided to demonstrate the approach in practical use. © 2008 Wiley Periodicals, Inc. Naval Research Logistics 2009
Models and branch‐and‐cut algorithms for the Steiner tree problem with revenues, budget and hop constraints
Authors: Costa Alysson M. , Cordeau Jean‐François , Laporte Gilbert
Published: December 2008

The Steiner tree problem with revenues, budget and hop constraints is a variant of the Steiner tree problem with two main modifications: (a) besides the costs associated with arcs, there are also revenues associated with the vertices, and (b) there are additional budget and hop constraints, which impose limits on the total cost of the network and on the number of edges between any vertex and the root, respectively. This article introduces and compares several mathematical models for this problem and describes two branch‐and‐cut algorithms, which solve to optimality instances with up to 500 vertices and 625 edges. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
Approximating the smallest k‐edge connected spanning subgraph by LP‐rounding
Authors: Gabow Harold N. , Goemans Michel X. , Tardos Éva , Williamson David P.
Published: December 2008

The smallest k‐ECSS problem is, given a graph along with an integer k, find a spanning subgraph that is k‐edge connected and contains the fewest possible number of edges. We examine a natural approximation algorithm based on rounding an LP solution. A tight bound on the approximation ratio is 1 + 3/k for undirected graphs with k > 1 odd, 1 + 2/k for undirected graphs with k even, and 1 + 2/k for directed graphs with k arbitrary. Using iterated rounding improves the first upper bound to 1 + 2/k. On the hardness side we show that for some absolute constant c > 0, for any integer k ≥ 2 (k ≥ 1), a polynomial‐time algorithm approximating the smallest k‐ECSS on undirected (directed) multigraphs to within ratio 1 + c/k would imply P = NP. © 2008 Wiley Periodicals, Inc. NETWORKS, 2009
The boundary element method with Lagrangian multipliers
Authors: Gatica Gabriel N. , Healey Martin , Heuer Norbert
Published: December 2008

On open surfaces, the energy space of hypersingular operators is a fractional order Sobolev space of order 1/2 with homogeneous Dirichlet boundary condition (along the boundary curve of the surface) in a weak sense. We introduce a boundary element Galerkin method where this boundary condition is incorporated via the use of a Lagrangian multiplier. We prove the quasi‐optimal convergence of this method (it is slightly inferior to the standard conforming method) and underline the theory by a numerical experiment.

The approach presented in this article is not meant to be a competitive alternative to the conforming method but rather the basis for nonconforming techniques like the mortar method, to be developed. © 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2009
On a 1D inverse problem with interfaces in bioengineering
Authors: Troparevsky M.I. , Rubio D.
Published: December 2008

In this work we study a 1D Inverse Problem that is motivated by the electroencephalogram (EEG) problem, which consists in the use of EEG data to find the location of electric sources of neural activity in the brain. We analize a 1D differential equation with a unique pointwise source. We consider different source models and study the sensitivity of the solution with respect to a parameter associated with the location of the source. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of muscle determinant for different gait speeds by proper orthogonal decomposition
Authors: Sirisup Sirod , Boonsinsukh Rumpa
Published: December 2008

In this investigation, we explore the use of the proper orthogonal decomposition (POD) on electromyography (EMG) of the leg muscles, with the objective of elucidating the muscles behavior for each gait speeds. Four different gait speeds were used in the study: slow, comfortable, fast and fastest walking. The electromyographic data used in this study were recorded from 12 bilateral lower limb muscles: tensor fascia latae (TFL), semitendinosus (ST), vastus medialis (VM), rectus femoris (RF), tibialis anterior (TA) and medial gastrocnemius (MG). Results indicate that the primary muscles for these gait speeds were bilateral TFL which act alternately to accept weight bearing on each leg. The same muscles also show another dominant function when working simultaneously in pelvic stabilization. In addition, we found that when the speed of walking increases, the number of muscle determinants for gait has been added. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of a boundary layer separation
Authors: Uruba V. , Knob M. , Popelka L.
Published: December 2008

The results of experimental study on a boundary layer separation control are given in the paper. The boundary layer on a flat wall is subjected to adverse pressure gradient. The active control strategy evolving a synthetic jet has been applied. The separation process is investigated using TR‐PIV method. Dynamical aspects of the phenomenon are analyzed in details. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Integer solution of a set of bilinear equations
Authors: Nowak Michal , Ziólko Mariusz
Published: December 2008

An efficient method for a design of transmultiplexer filters is suggested. The perfect reconstruction conditions lead to the bilinear equations for FIR filters coefficients. The method of solving these equations results from the presented theorem. Usefulness of the algorithm in fixed‐point arithmetic is the crucial issue. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Continuous solutions of some boundary layer problem (Poster Presentation)
Authors: Dreglea Aliona I. , Sidorov Nikolay A.
Published: December 2008

The continuous solutions for BVP of third order nonlinear differential equations appears in [1] mathematical model of the melt spinning process. The existence theorem is proved for such BVP. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, thermal, and rheological properties of poly(trimethylene terephthalate)/BaSO4 nanocomposites
Authors: Yao Chenguang , Yang Guisheng
Published: December 2008

A novel method was developed for fabricating poly(trimethylene terephthalate) (PTT)/BaSO4 nanocomposites using in situ polymerization. A nano‐BaSO4 suspension was prepared by reacting H2SO4 with Ba(OH)2 in 1,3‐propanediol (PDO). The mean size of original nano‐BaSO4 is 15–23 nm. PTT matrix was synthesized by condensation polymerization of bis(3‐hydroxypropyl terephthalate) after the completion of transesterification of dimethyl terephthalate (DMT) with PDO. It was found that the addition of BaSO4 had little influence on the synthesis of PTT. The properties of nanocomposites with a wide range of BaSO4 fraction were systematically studied. The morphologies of the composites were investigated by transmission electron microscopy (TEM), which showed that agglomerate structures did not form until BaSO4 content higher than 8 wt%. The thermal properties of the nanocomposites were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The DSC results revealed that the triple endothermic melting phenomenon is only observed for the nanocomposites which contained 4 wt% BaSO4, other samples exhibit double endothermic melting. These results indicated that nano‐BaSO4 could induce a microcrystal to form more perfect morphology and restrain the formation of much thicker lamellar crystallinity, that is, nano‐BaSO4 could induce the formation of more uniform crystallinity. Besides, the crystallization ability of the composites was greatly improved by loading nano‐BaSO4. The TGA results suggested that nano‐BaSO4 slightly increased the maximum‐decomposing‐rate temperature 1 (Tmax1), but markedly increased the maximum‐decomposing‐rate temperature 2 (Tmax2). Furthermore, the steady‐state shear behavior of samples was investigated by a parallel‐plate rheometer. The storage modulus (G') and loss modulus (G”) curves shifted to higher modulus upon addition of 2–16 wt% of nano‐BaSO4. All of the samples investigated exhibited the expected shear‐thinning behavior. Proper contents of nano‐BaSO4 would decrease the shear viscosity of nanocomposites, whereas superfluous amounts would greatly increase the viscosity of nanocomposites and the composites which loaded 8 wt% nano‐BaSO4 revealed an equivalent shear viscosity compared to pure PTT. Copyright © 2008 John Wiley & Sons, Ltd.
Stem cells in pathobiology and regenerative medicine
Authors: Alison MR
Published: December 2008

This issue of the Journal of Pathology contains 16 articles largely dealing with the role of tissue‐specific adult stem cells in the pathogenesis of disease, notably cancer. These authoritative reviews begin by describing the current knowledge regarding the identity and molecular regulation of normal tissue‐specific stem cells, before itemizing their role in the aetiology and progression of disease. Fundamental concepts regarding the stem cell niche have been gleaned from studies of germ line stem cells in Drosophila and Caenorhabditis elegans, and these are described in detail in this issue. Somatic cell reprogramming, a process underlying not only therapeutic cloning but also the production of induced pluripotent stem (iPS) cells, is further discussed. Much attention is given to embryonic stem (ES) and iPS cells within the scientific community; this issue of the Journal of Pathology redresses this imbalance by illustrating the pivotal role of adult stem cells in much of human disease. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
The use of a protein and energy dense eicosapentaenoic acid containing supplement for malignancy‐related weight loss in children
Authors: Bayram Ibrahim , Erbey Fatih , Celik Nilgun , Nelson Jeffrey L. , Tanyeli Atila
Published: December 2008

Background

The aim of nutritional therapy in cancer patients is to prevent weight loss and to improve functional capacity and quality of life. Clinical studies however, have continued to demonstrate that a reduction in body weight loss is difficult to achieve in cancer cachexia. Several studies have shown that supplementation with eicosapentaenoic acid (EPA), an omega‐3 fatty acid, has anti‐cachectic effects in adult cancer patients. This study evaluated the clinical effects of a protein and energy dense EPA containing nutritional supplement in a group of pediatric cancer patients receiving active chemotherapy treatment.

Methods

The study was a prospective, randomized, single center, open‐label design. Fifty‐two patients diagnosed with pediatric malignant disease and receiving intensive chemotherapy were included. Thirty‐three patients received a nutritional supplement containing EPA in addition to their regular food intake. Nineteen control patients did not receive supplementation. Patients were examined and their data (body weight, body mass index, and weight percentile) were recorded regularly once a month for 3 months. A subgroup of patients was evaluated for 6 months.

Results

At 3 months, there were significantly fewer patients in the treatment group as compared to controls that showed losses in body weight (P = 0.001), BMI (P = 0.002), and a negative deviation in weight percentile (P = 0.021). In addition, remission rate was significantly (P = 0.036) higher in the treatment group as compared to controls.

Conclusions

This study demonstrates a decrease in cancer‐induced weight loss in pediatric patients fed a protein and energy dense nutrition supplement containing EPA. Pediatr Blood Cancer 2009;52:571–574. © 2008 Wiley‐Liss, Inc.
Apoptosis‐inducing activity ofHelleborus nigerin ALL and AML
Authors: Jesse Patrick , Mottke Gritt , Eberle Jürgen , Seifert Georg , Henze Günter , Prokop Aram
Published: December 2008

Background

Helleborus nigeris used in the adjuvant treatment of different tumors in anthroposophical medicine. Indications include various types of brain tumors in children, as well as prostate cancer, leukemia and lymphoma. Our aim was to investigate the therapeutic effects of these extracts apart from the traditional use.

Procedures

: We used an aqueous whole plant extract ofH. nigerin different cancer and leukemia cell lines and primary cells of patients with childhood ALL and AML and identified the main mechanisms of action.

Results

A strong inhibition of proliferation is caused by specific apoptosis induction, which is executed via the mitochondrial pathway and caspase‐3 processing. Apoptosis could be detected in lymphoma (BJAB), leukemia (Reh, Nalm6, Sup‐B15) and melanoma (Mel‐HO) cells and overcomes a Bcl‐2‐mediated block of apoptosis. In primary cells of patients with childhood ALL and AML, which were partly poor responding to doxorubicin and daunorubicin, a strong apoptosis induction was determined. In combination with the vinca alkaloid vincristine, strong synergistic effects were detected in BJAB cells.

Conclusion

We demonstrate in vitro efficacy ofH. nigerextract in cells of hematological malignancies; these studies should encourage in vivo experiments. Pediatr Blood Cancer 2009;52:464–469. © 2008 Wiley‐Liss, Inc.
Mechanical performance of resol type phenolic resin/layered silicate nanocomposites
Authors: Tasan C. Cem , Kaynak Cevdet
Published: December 2008

Clay addition has been shown to affect polymer resins positively in terms of several physical and chemical properties, including mechanical performance, high temperature endurance and durability. These increases are limited only to relatively low concentrations of reinforcement phase, but at these low concentrations polymer/layered silicate nanocomposites (P/LS NC) have shown to exhibit higher mechanical performance than fiber reinforced polymer composites. This is among the several reasons that make P/LS NC's one of the most widely studied class of materials today. In this study, the mechanical performance of resol type phenolic resin/layered silicate nanocomposite specimens was examined by carrying out 3‐point bending, Charpy impact and fracture toughness tests to couple the observations, microstructural analysis is done through X‐ray diffraction and scanning electron microscopy. The effects of especially three factors; cure method, clay amount, and clay modification were investigated. It was concluded that highest mechanical performance was obtained by the acid curing of the phenolic resin with very low amounts (e.g., 0.5%) of either very hydrophobic or very hydrophilic Na‐montmorillonite clay additions. Improvements as high as 7% in flexural strength, 11% in flexural strain at break, 16% in Charpy impact strength, and 66% in fracture toughness values were obtained. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
The mechanical/thermal properties of microcellular injection‐molded poly‐lactic‐acid nanocomposites
Authors: Hwang Shyh‐Shin , Hsu Peming P. , Yeh Jui‐Ming , Chang Kung‐Chin , Lai Ying‐Zhong
Published: December 2008

This study investigated the influence of montmorillonite (MMT) content on the mechanical/thermal properties of microcellular injection‐molded polylactide (PLA)/clay nanocomposites. Carbon dioxide was the blowing agent. The PLA/MMT nanocomposites were prepared by twin screw extrusion. The results showed that as MMT content is increased, tensile strength, impact strength, and cell density decrease. This is caused by the speed degradation of PLA due to the addition of MMT. MMT decreases the crystallization temperature but increases the decomposition temperature of the nanocomposites. The XRD results showed that the layer spacing of the clay increases as MMT content increases. TEM pictures showed that the MMT is well dispersed within the PLA matrix. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers.
Nanostructured fly ash–styrene butadiene rubber hybrid nanocomposites
Authors: Paul K. Thomas , Pabi S.K. , Chakraborty K.K. , Nando G.B.
Published: December 2008

Hybrid nanocomposites of styrene butadiene rubber (SBR) with nanostructured fly‐ash (NFA) were prepared in the laboratory by melt blending technique in an internal mixer. Curatives were added on a laboratory two‐roll mill. Curing characteristics as well as physico‐mechanical properties of the composites were evaluated. A comparison on SBR composites filled with fresh fly‐ash (FFA); carbon black (CB) and precipitated silica (PS) has been reported. In general, SBR‐NFA composites exhibit higher state of cure and higher strength properties as compared with HAF black‐filled and fresh fly‐ash‐filled SBR composites at equivalent loadings. This may be attributed to the higher reinforcing ability of NFA. This fact has also been supported by the swelling studies and Kraus' plot. Tear strength and abrasion resistance of the SBR‐NFA composites were superior to FFA‐filled and precipitated silica‐filled vulcanizates, but were inferior to carbon black‐ filled SBR vulcanizates. The SBR‐NFA composites showed lower hardness as compared with both the carbon black‐filled and silica‐filled composites. Transmission electron microscopy and scanning probe microscopy studies revealed that the NFA particles are well dispersed in the SBR matrix. These results were further supported by fracture surface analysis under the SEM, which revealed the role of NFA in the prevention of fracture propagation. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Modified continuous carbon fiber‐reinforced poly(phthalazinone ether sulfone ketone) composites by blending polyetherimide and polyethersulfone
Authors: Zheng Liang , Liao Gong‐Xiong , Gu Tie‐Sheng , Han Yong‐Jin , Jian Xi‐Gao
Published: December 2008

Poly(phthalazinone ether sulfone ketone) (PPESK) is a novel high performance thermoplastic with outstanding high temperature resistance and excellent mechanical properties and therefore, it is a very ideal candidate matrix for advanced composites. However, its high melting viscosity makes the melting process difficult. In this article, two well‐known high performance thermoplastics, polyetherimide (PEI) and polyethersulfone (PES) were introduced to PPESK in order to reduce the melting viscosity of PPESK and to improve the properties of composites. The effect of addition of PEI and PES on the resultant composites was studied. A series of unidirectional composites were made of PPESK and its PEI and PES blends as matrix and continuous carbon fiber (T700) as reinforcement. The solution prepregging method and hot‐press molding method were used in preparation of composites. The effects of polymer blends matrix on mechanical properties, interfacial adhesion, and fracture mode were studied by three points bending, interlaminar shearing, porosity, and scanning electron microscope test. The results show that the mechanical properties and interfacial adhesion increases, and the porosity decrease after blending PEI or PES in the matrix. Addition of PEI and PES to PPESK results in an obvious transition of fracture mode. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Effects of stearic acid on the interface and performance of polypropylene/superfine down powder composites
Authors: Liu Xin , Xu Weilin , Peng Xuqiang
Published: December 2008

To manufacture the hygroscopic sheets available for functional application, superfine down powder (SDP) and stearic acid modified superfine down powder (MSDP) were, respectively, blended and extruded with polypropylene (PP) to produce composite pellets, and the extruded pellets were hot‐pressed into composite sheets. The chemical reaction between SDP and stearic acid was characterized using the attenuated total reflection attachment on the Fourier transform infrared. PP/MSDP composites showed more uniform powder dispersion in PP matrix, higher compatibility, and better mechanical properties than that of PP/SDP composites, which showed an evident decrease in tensile strength and elongation at break compared with pure PP. It was worth noting that the Young's modulus of PP/SDP composites was higher than that of pure PP, but lower than that of PP/MSDP composites. The addition of SDP led to a large increase in water absorption of PP/SDP composites. However, the water absorption of PP/MSDP composites decreased slightly compared with that of PP/SDP composites. Furthermore, the effects of SDP and MSDP on the microstructural and thermal properties of different composites were also investigated, respectively. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Decisional needs assessment regarding Down syndrome prenatal testing: a systematic review of the perceptions of women, their partners and health professionals
Authors: St‐Jacques Sylvie , Grenier Sonya , Charland Marc , Forest Jean‐Claude , Rousseau François , Légaré France
Published: December 2008

Objective

To identify decisional needs of women, their partners and health professionals regarding prenatal testing for Down syndrome through a systematic review.

Methods

Articles reporting original data from real clinical situations on sources of difficulty and/or ease in making decisions regarding prenatal testing for Down syndrome were selected. Data were extracted using a taxonomy adapted from the Ottawa Decision‐Support Framework and the quality of the studies was assessed using Qualsyst validated tools.

Results

In all 40 publications covering 32 unique studies were included. The majority concerned women. The most often reported sources of difficulty for decision‐making in women were pressure from others, emotions and lack of information; in partners, emotion; in health professionals, lack of information, length of consultation, and personal values. The most important sources of ease were, in women, personal values, understanding and confidence in the medical system; in partners, personal values, information from external sources, and income; in health professionals, peer support and scientific meetings.

Conclusion

Interventions regarding a decision about prenatal testing for Down syndrome should address many decisional needs, which may indeed vary among the parties involved, whether women, their partners or health professionals. Very little is known about the decisional needs of partners and health professionals. Copyright © 2008 John Wiley & Sons, Ltd.
A novel method for extracting DNA from chorionic villus samples for use in CVS–PCR, which ensures complete villus dissociation
Authors: Holgado Elaine , Holgado Ben , Liddle Stuart , Ballard Terry , Levett Lisa
Published: December 2008

Objective

To demonstrate that glass disruption beads dissociate chorionic villus samples releasing DNA from mesenchymal and cytotrophoblast cells that is suitable for processing by CVS–PCR (rapid molecular aneuploidy testing). This method is quicker than conventional methods and may limit discrepancies between PCR and karyotype in certain types of placental mosaicism.

Method

DNA was extracted from villus samples by mechanical disruption of the cells using glass beads. This method was compared to collagenase incubation followed by chelex extraction of the digested villus. PCR data generated were compared using standard criteria.

Results

DNA extracted by glass bead disruption generated data of equivalent quality to that obtained from DNA extracted using conventional collagenase and chelex‐based extraction method. The case study demonstrates probable cytotrophoblast enrichment of a sample when processed by collagenase digestion and chelex incubation. Re‐extraction of the digested sample by glass bead disruption resulted in cytotrophoblast and mesenchyme cells contributing to the supernatant.

Conclusion

Glass bead disruption of chorionic villus samples is an effective, inexpensive and rapid DNA extraction method that dissociates villus ensuring that DNA from both cytotrophoblast and mesenchyme cells is represented in the supernatant. Extracted DNA produced is suitable for CVS–PCR and can be stored stably at − 20 °C. Copyright © 2008 John Wiley & Sons, Ltd.
Holographic polymer‐dispersed liquid crystals using vinyloxytrimethylsilane
Authors: Jeong Eun Hwa , Woo Ju Yeon , Cho Yeong Hee , Jeong Yeong Keun , Kim Kwang Ho , Kim Byung Kyu
Published: December 2008

BACKGROUND: To reduce the driving voltage of transmission holographic polymer‐dispersed liquid crystals (HPDLCs), the polymer interface was modified by incorporating various amounts of vinyloxytrimethylsilane (VOTMS) monomer to the conventional grating formulation based on polyurethane acrylate (PUA).

RESULTS: With the addition of increasing amounts of VOTMS, the contact angle of the film and the droplet size of the liquid crystal (LC) monotonically increased, implying that the VOTMS segments of the polymer are preferentially exposed to the interfaces and provide greater immiscibility with LC molecules. The operating voltage monotonically decreased with increasing VOTMS content with a minimum switching voltage of about 15 V with a response time of about 10 ms. However, in the presence of VOTMS, the droplets coalesced and caused random scattering, thus lowering the off‐state diffraction efficiency below that of virgin PUA.

CONCLUSION: It was found that VOTMS was essential to drive the film. The VOTMS segments of the polymer are preferentially exposed to the polymer/LC interfaces and decrease the surface anchoring strength and also influence the orientation of LC droplets. Also, lower molecular weight bifunctional polypropylene glycol generally gave greater diffraction efficiency, confirming that grating formation is favoured with higher crosslink density due to the greater polymer/LC phase separation. Copyright © 2008 Society of Chemical Industry