bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Selective and Sensitive Detection of Dopamine in the Presence of Excessive Ascorbic Acid Using Electrodes Modified with C60‐Functionalized Multiwalled Carbon Nanotube Films
Authors: Zhu Huarui , Wu Wei , Zhang Hua , Fan Louzhen , Yang Shihe
Published: November 2009

Electrochemical detection of dopamine (DA) in the presence of a large excess of ascorbic acid (AA) was investigated with a novel all‐carbon nanocomposite film of C60‐MWCNTs (C60‐functionalized multi‐walled carbon nanotubes) using a bare MWCNTs film as control. Although both films can selectively detect DA from AA by separating their oxidation potentials, the C60‐MWCNTs film shows special selectivity and good sensitivity for detecting DA. On one hand, the C60‐MWCNTs composite film shows a higher activity for DA oxidation with enhanced peak current. On the other hand, the C60‐MWCNTs composite film effectively suppresses the oxidation of AA. Remarkably, it is found that the oxidation current of DA is over 2 times higher than that of AA even when the concentration of AA is about 3 to 4 orders of magnitude higher than that of DA. This offers a tremendous advantage for the simple and clean detection of DA free of the interfering AA signal in a real assay. Cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectrometry are used to characterize the C60‐MWCNTs composite film. These novel properties are interpreted to arise from the facile electron transfer between C60 and MWCNTs in the C60‐MWCNTs nanocomposite film.
Electrical and Sensing Properties of Single‐Walled Carbon Nanotubes Network: Effect of Alignment and Selective Breakdown
Authors: Lim Jae‐Hong , Phiboolsirichit Nopparat , Mubeen Syed , Rheem Youngwoo , Deshusses Marc A. , Mulchandani Ashok , Myung Nosang V
Published: November 2009

The electrical transport and NH3 sensing properties of randomly oriented and aligned SWNT networks were presented and discussed. The results indicate that aligned SWNT‐FETs have better FET characteristics due to the reduced number of interconnected nodes. This was particularly true as the resistance of the devices increased. Gated electrical breakdown was implemented to selectively remove metallic (m‐) SWNTs, thereby reducing scattering centers. This technique provided significant improvements in FET characteristics resulting in greater on/off ratio (e.g. 104). AC dielectrophoretic alignment followed by selective electrical breakdown of m‐SWNTs can significantly enhance the semiconducting properties of SWNT networks which resulted in highly sensitive sensors.
Nrf2 regulates microglial dynamics and neuroinflammation in experimental Parkinson's disease
Authors: Rojo Ana I. , Innamorato Nadia G. , Martín‐Moreno Ana M. , De Ceballos María L. , Yamamoto Masayuki , Cuadrado Antonio
Published: November 2009

Neural injury leads to inflammation and activation of microglia that in turn may participate in progression of neurodegeneration. The mechanisms involved in changing microglial activity from beneficial to chronic detrimental neuroinflammation are not known but reactive oxygen species (ROS) may be involved. We have addressed this question in Nrf2‐knockout mice, with hypersensitivity to oxidative stress, submitted to daily inoculation of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) for 4 weeks. Basal ganglia of these mice exhibited a more severe dopaminergic dysfunction than wild type littermates in response to MPTP. The amount of CD11b‐positive/CD45‐highly‐stained cells, indicative of peripheral macrophage infiltration, did not increase significantly in response to MPTP. However, Nrf2‐deficient mice exhibited more astrogliosis and microgliosis as determined by an increase in messenger RNA and protein levels for GFAP and F4/80, respectively. Inflammation markers characteristic of classical microglial activation, COX‐2, iNOS, IL‐6, and TNF‐α were also increased and, at the same time, anti‐inflammatory markers attributable to alternative microglial activation, such as FIZZ‐1, YM‐1, Arginase‐1, and IL‐4 were decreased. These results were confirmed in microglial cultures stimulated with apoptotic conditioned medium from MPP+‐treated dopaminergic cells, further demonstrating a role of Nrf2 in tuning balance between classical and alternative microglial activation. This study demonstrates a crucial role of Nrf2 in modulation of microglial dynamics and identifies Nrf2 as molecular target to control microglial function in Parkinson's disease (PD) progression. © 2009 Wiley‐Liss, Inc.
An empirical investigation into the causes of failure of the monetary model of the exchange rate
Authors: Smith P. N. , Wickens M. R.
Published: November 2009

The purpose of this paper is to attempt to provide measures of the relative importance of the principal causes of the failure of the monetary model of the exchange rate. Secondly, the random walk hypothesis for the exchange rate is tested. The methodology employed is new and has wide application elsewhere. It involves explicitly modelling the misspecification by time series techniques. The results confirm the importance of the breakdown of the PPP assumption but they also show that misspecification of the money market is equally important. The results further show that lagged information can also improve upon the random walk model of the exchange rate.
The behaviour of U.K. export prices of manufactured goods 1970–1983
Authors: Cuthbertson Keith
Published: November 2009

This paper examines the importance of expectations in the determination of U.K. export prices. Export prices are found to depend upon expectations of total domestic unit costs and foreign prices. The non‐linear restrictions implied by the forward‐looking model are found to hold and it performs adequately relative to a backward‐looking error feedback model. The law of one price is rejected and the evidence is consistent with imperfect competition in export markets.
Zero expenditures and the estimation of engel curves
Authors: Keen Michael
Published: November 2009

Over the brief interview periods typical of budget surveys (such as the U.K. Family Expenditure Survey) households' recorded expenditures are liable to be misleading indicators of their underlying consumption. Most starkly, a household may not be observed to purchase commodities that it nevertheless consumes. This paper considers the implications of such measurement errors for the estimation of demand systems, and derives a consistent estimator for the special case of linear Engel curves.
MMP levels in the response to degradable implants in the presence of a hydroxamate‐based matrix metalloproteinase sequestering biomaterial in vivo
Authors: Khan Omar F. , Jean‐Francois Jacques , Sefton Michael V.
Published: November 2009

The inflammatory response to an implanted tissue engineered construct alters the remodeling that occurs and this can diminish the intended therapeutic effect. It was hypothesized that the use of a hydroxamate‐based matrix metalloproteinase (MMP) sequestering biomaterial (MI) in the form of ∼200 μm microspheres would lower the amount and activity of MMP in vivo in response to a subcutaneous, degradable implant (gelatin or Integra® disc). MMP degrade extracellular matrix, facilitating inflammatory cell migration and local remodeling of the implant environment. Gelatin or Integra® discs were implanted subcutaneously in the backs of CD1 mice together with 30 mg of MI microspheres or with 30 mg of similarly sized control poly(methyl methacrylate) (PMMA) microspheres in a paired study. To sample the implant space, weakly adsorbed protein or attached cells were recovered from explanted discs by soaking the discs in PBS overnight at 4°C. Unexpectedly, MMP‐2, ‐8, ‐9, and TIMP‐1 levels were surprisingly similar in this recovered fluid for the two treatments. Also, there were significantly more (and at day 4 an order of magnitude more) leukocytes recovered from the gelatin discs coimplanted with the MI microspheres than with the PMMA control. It is suggested that the MI microspheres disturbed the natural MMP control pathway leading to high‐leukocyte numbers, especially at early times. These results highlight the challenge associated with controlling the fate of tissue engineered constructs in vivo. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Preparation and in vitro evaluation of bioactive glass (13–93) scaffolds with oriented microstructures for repair and regeneration of load‐bearing bones
Authors: Fu Qiang , Rahaman Mohamed N. , Bal B. Sonny , Brown Roger F.
Published: November 2009

Bioactive glass (13–93) scaffolds with oriented microstructures, referred to as ‘columnar’ and ‘lamellar’, were prepared by unidirectional freezing of suspensions, and evaluated in vitro for potential use in the repair and regeneration of load‐bearing bones in vivo. Both groups of scaffolds showed an ‘elastic–plastic’ mechanical response in compression, large strain for failure (>20%), and strain rate sensitivity, but the columnar scaffolds had the additional advantages of higher strength and larger pore width. At the equivalent porosity (55–60%) and deformation rate (0.5 mm/min), the columnar scaffolds had a compressive strength of 25 ± 3 MPa, elastic modulus of 1.2 GPa, and pore width of 90–110 μm, compared to values of 10 ± 2 MPa, 0.4 GPa, and 20–30 μm, respectively, for the lamellar scaffolds. Cellular response to the scaffolds was evaluated using murine MLO‐A5 cells, an osteogenic cell line. While the cellular response to both groups of scaffolds was better than control wells, the columnar scaffolds with the larger pore width provided the most favorable substrate for cell proliferation and function. These results indicate that 13–93 bioactive glass scaffolds with the columnar microstructure could be used for the repair and regeneration of load‐bearing bones in vivo. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Biocompatibility of polyhydroxyalkanoate as a potential material for ligament and tendon scaffold material
Authors: Rathbone S. , Furrer P. , Lübben J. , Zinn M. , Cartmell S.
Published: November 2009

There is a strong need for new biodegradable materials that are suitable for scaffolds in tissue engineering of tendons and ligaments. In many cases, quick degradation rates are favorable, however, with respect to ligament and tendon replacement, slowly degrading polymers are clearly favored. Prime candidates are members of the large class of polyhydroxyalkanoates (PHAs), which are thermoplastic/elastomeric biopolyesters that are slowly degraded by surface erosion. Moreover, their physico‐mechanical properties can be tailored during biosynthesis in bacteria or by chemical modifications. They may be spun into fibers, coated on surfaces or be part of composites. This study has investigated the biocompatability of seven different thermoplastic or elastomeric PHAs using L929 murine fibroblast cells. Cell viability and proliferation over 7 days was analyzed with live/dead staining and a picogreen assay. In addition, extracellular matrix production was measured with the hydroxyproline assay after 14 days. It was found that cell attachment to the PHA film ranged from 85–99% after 7 days. Three PHA films (PHBV (92/8), PHOUE‐POSS and PHUE‐O3) supported similar cell viability in comparison to the controls performed on tissue culture plastic (polystyrene), whereas the biomaterials (PHUA, PHUE, PHB and PHOUE) showed fewer viable cells than in controls. PHB, PHUE‐O3, and PHBV with a water contact angle below 85° supported a similar amount of collagen production in comparison to the tissue culture plastic controls. PHUA, PHUE, PHOUE, and PHOUE‐POSS showed a decrease in collagen production in comparison to the controls after 14 days. Overall, PHB, PHBV, and PHUE‐O3 demonstrated good performance with regards to potential use as a tissue‐engineering scaffold. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
Inhibition of tumor proteasome activity by gold–dithiocarbamato complexes via both redox‐dependent and ‐independent processes
Authors: Zhang Xia , Frezza Michael , Milacic Vesna , Ronconi Luca , Fan Yuhua , Bi Caifeng , Fregona Dolores , Dou Q. Ping
Published: November 2009

We have previously reported on a gold(III) complex, namely [AuBr2(DMDT)] (N,N‐dimethyldithiocarbamate) showing potent in vitro and in vivo growth inhibitory activities toward human cancer cells and identifying the cellular proteasome as one of the major targets. However, the importance of the oxidation state of the gold center and the involved mechanism of action has yet to be established. Here we show that both gold(III)− and gold(I)–dithiocarbamato species, namely [AuBr2(ESDT)] (AUL12) and [Au(ESDT)]2 (AUL15), could inhibit the chymotrypsin‐like activity of purified 20S proteasome and 26S proteasome in human breast cancer MDA‐MB‐231 cells, resulting in accumulation of ubiquitinated proteins and proteasome target proteins, and induction of cell death, but at significantly different levels. Gold(I)‐ and gold(III)‐compound‐mediated proteasome inhibition and cell death induction were completely reversed by the addition of a reducing agent, dithiothreitol or N‐acetyl‐L‐cysteine, suggesting the involvement of redox processes. Furthermore, treatment of MDA‐MB‐231 cells with gold(III) compound (AUL12), but not the gold(I) analog (AUL15), resulted in the production of significant levels of reactive oxygen species. Our study provides strong evidence that the cellular proteasome is an important target of both gold(I) and gold(III)–dithiocarbamates, but distinct cellular mechanisms of action are responsible for their different overall effect. J. Cell. Biochem. 109: 162–172, 2010. © 2009 Wiley‐Liss, Inc.
Protein alterations induced by long‐term agonist treatment of HEK293 cells expressing thyrotropin‐releasing hormone receptor and G11α protein
Authors: Drastichova Zdenka , Bourova Lenka , Hejnova Lucie , Jedelsky Petr , Svoboda Petr , Novotny Jiri
Published: November 2009

This study aimed to determine whether sustained stimulation with thyrotropin‐releasing hormone (TRH), a peptide with important physiological functions, can possibly affect expression of plasma membrane proteins in HEK293 cells expressing high levels of TRH receptor and G11α protein. Our previous experiments using silver‐stained two‐dimensional polyacrylamide gel electrophoretograms did not reveal any significant changes in an overall composition of membrane microdomain proteins after long‐term treatment with TRH of these cells (Matousek et al.2005Cell Biochem Biophys 42: 21–40). Here we used a purified plasma membrane fraction prepared by Percoll gradient centrifugation and proteins resolved by 2D electrophoresis were stained with SYPRO Ruby gel stain. The high enrichment in plasma membrane proteins of this preparation was confirmed by a multifold increase in the number of TRH receptors and agonist stimulated G‐protein activity, compared to postnuclear supernatant. By a combination of these approaches we were able to determine a number of clearly discernible protein changes in the plasma membrane‐enriched fraction isolated from cells treated with TRH (1 × 10−5 M, 16 h): 4 proteins disappeared, the level of 18 proteins decreased and the level of 39 proteins increased. Our concomitant immunochemical determinations also indicated a clear down‐regulation of Gq/11α proteins in preparations from hormone‐treated cells. In parallel, we observed decrease in caspase 3 and alterations in some other apoptotic marker proteins, which were in line with the presumed antiapoptotic effect of TRH. J. Cell. Biochem. 109: 255–264, 2010. © 2009 Wiley‐Liss, Inc.
A novel and green method for the synthesis of highly substituted isoquinoline derivatives in ionic liquid
Authors: Wang Xiang‐Shan , Wu Jian‐Rong , Li Qing , Zhang Mei‐Mei
Published: November 2009

magnified image

A series of new highly substituted isoquinoline derivatives was obtained from the reaction of 2‐(1‐substituted piperidin‐4‐ylidene)malononitrile, benzaldehyde and malononitrile or cyanoacetate in ionic liquid at 50°C. This novel procedure was different from the previous method in the synthesis of isoquinoline using pyridine fragment as reactant to construct benzene ring, and as well as had the advantages of one‐pot, mild and environmentally benign. A possible mechanism was proposed based on the further experimental results. J. Heterocyclic Chem., (2009).
A novel synthesis of some 1,4‐phenylene‐bis‐heterocyclic carboxamide derivatives
Authors: Abdelrazek Fathy M. , Metwally Nadia H. , Kassab Nazmi A. , Sobhy Nehal A.
Published: November 2009

magnified image

N,N′‐(1,4‐phenylene)bis(3‐oxo‐3‐phenylpropanamide) 1 reacts with DMFDMA in refluxing toluene to afford N,N′‐(1,4‐phenylene)bis(2‐benzoyl‐3‐(dimethylamino)acrylamide) 2. Compound 2 reacts with a twofold excess of the active methylene reagents 3a, 3b, 3c to afford the pent‐2‐enediamide derivatives 7 and 8a, 8b, respectively. Compounds 7 and 8a could be cyclized to afford the same compound N,N′‐(1,4‐phenylene)bis(5‐cyano‐6‐oxo‐2‐phenyl‐1,6‐dihydropyridine‐3‐carboxamide) 9a while 8b was cyclized to afford the 6‐thioxo analogue 9b. Compound 2 reacts with hydrazine derivatives 10a, 10b in refluxing ethanol/piperidine to afford the hydrazinylacrylamide derivatives 11a, 11b, which have been cyclized to the corresponding N,N′‐(1,4‐phenylene)bis(1H‐pyrazole‐4‐carboxamide) derivatives 12a, 12b, respectively. Compound 2 reacts also with urea derivatives 13a, 13b, 13c in refluxing ethanol/piperidine to afford the N,N′‐(1,4‐phenylene)bis(2‐benzoyl‐3‐substituted‐acrylamide) derivatives 14a‐c, which could be cyclized into N,N′‐(1,4‐phenylene)bis(6‐phenyl‐1,2‐dihydropyrimidine‐5‐carboxamide)‐2‐oxo; 2‐thioxo or 2‐imino derivatives 15a, 15b, 15c, respectively. J. Heterocyclic Chem., (2009).
Alterations in GluR2 AMPA receptor phosphorylation at serine 880 following group I metabotropic glutamate receptor stimulation in the rat dorsal striatum
Authors: Ahn Sung Min , Choe Eun Sang
Published: November 2009

Phosphorylation of ionotropic glutamate receptors in the brain plays a crucial role in the regulation of synaptic plasticity. In this study, we investigated the regulation of α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA) receptor phosphorylation by thestimulation of group I metabotropic glutamate receptors (mGluRs) in the dorsal striatum in vivo. The results showed that intrastriatal infusion of the group I mGluR agonist, (RS)‐3,5‐dihydroxyphenylglycine (DHPG, 250 nmol), enhanced the sensitivity of GluR2 subunit in its phosphorylation at serine 880 (S880) in the dorsal striatum. This enhancement of the sensitivity of GluR2‐S880 phosphorylation was reduced by blocking group I mGluRs andN‐methyl‐D‐aspartate (NMDA) receptors. Similar reduction of the enhancement was also induced by inhibiting phospholipase C (PLC), calcium/calmodulin‐dependent protein kinase (CaMK), c‐Jun N‐terminal kinase (JNK), and protein kinase C (PKC). Inhibition of protein phosphatase (PP) 1/2A and calcineurin (PP2B) alone enhanced GluR2‐S880 phosphorylation in the dorsal striatum, whereas inhibition of these phosphatases did not further enhance the S880 phosphorylation by DHPG stimulation. In addition, inhibition of PP1/2A or PP2B also enhanced the phosphorylation of CaMKII, JNK and PKC. These data suggest that the phosphorylation of AMPA receptor GluR2 subunit at S880 is subject to the upregulation by the stimulation of group I mGluRs. Interactions among glutamate receptors, protein kinases, and PPs participate in this upregulation. © 2009 Wiley‐Liss, Inc.
Gold‐coated zinc oxide nanowire‐based substrate for surface‐enhanced Raman spectroscopy
Authors: Khan Muhammad A. , Hogan Timothy P. , Shanker B.
Published: November 2009

Zinc oxide nanowires with two distinct morphologies were synthesized on silicon substrates using a simple thermal evaporation and vapor transport method in an oxidizing environment. The as‐synthesized nanowires were coated with gold to allow excitation of surface plasmons over a broad frequency range. SERS studies with near‐IR excitation at 785 nm showed significant enhancement (average enhancement > 106) with excellent reproducibility to detect monolayer concentrations of 4‐methylbenzenethiol (4‐MBT) and 1,2‐benzendithiol (1,2‐BDT) probe molecules. The Raman enhancement showed a strong dependence on the gold film thickness, and the peak enhancement was observed for a ∼40‐nm‐thick film. The Raman enhancement was stronger for randomly oriented nanowires compared to aligned ones suggesting the importance of contributions from the junctions of nanowires. Copyright © 2009 John Wiley & Sons, Ltd.
Fundamental investigation of interfaces in particle reinforced steel sheets processed by thin strip casting
Authors: Martin M. , Weber S. , Theisen W. , Pyzalla A.R.
Published: November 2009

Along the steel industry history, the production of flat‐steel products has technologically evolved towards reducing slab thickness at the output of the continuous casting machine. This development has been related to the incessant requirement of providing a certain steel quality at lower costs. As a result of this procedure, the thin strip casting technology emerged in a commercial scale at the end of the nineties, with all the advantages of a near‐net‐shape manufacturing process. In particularly, the higher energy efficiency and reduced environmental impact turned it as a very promising and attractive technology for the steel industry.

With the purpose of obtaining new types of steel sheets, characterized by improved mechanical and tribological properties, reinforced steel strips have been produced by introducing slight modifications to a twin‐roll caster. In this regard, a considerable enhancement of the mechanical properties has been achieved.
Electron beam welding of titanium aluminides
Authors: Reisgen U. , Holk J. , Olschok S.
Published: November 2009

This paper gives an account of research which has been carried out on electron‐beam welded specimens made of high‐Nb γ/α2‐titanium aluminides (in short: TiAl).

The high niobium content of this alloy (5–8 %) has a positive effect on the strength and the creep resistance and also on the oxidation resistance.

The standard welding parameters weld speed and beam current and also additional beam oscillation have been used for the determination of factors which will effect the solidification morphology and structural constitution since those, in return, exert influence on the high cracking susceptibility of the alloy. In order to reduce the critical cooling rate, preheating which has a positive effect on crack formation has, in addition, been applied.

In a direct comparison of both alloys, micrographs and electron beam micro‐analyses of the developing weld structure and of the HAZ the effects of the beam parameters on both alloys have been established.
Semi‐empirische Berechnungsmethode zur Bestimmung des Grenzformänderungsdiagramms auf Basis mechanischer Kennwerte
Authors: Held C. , Dadrich J. , Denninger R. , Schleich R. , Weidenmann K. A. , Liewald M.
Published: November 2009

Ein probates Mittel zur Bewertung von Umformprozessen hinsichtlich der werkstofflichen Verarbeitbarkeit ist die Grenzformänderungskurve (Forming Limit Curve, kurz: FLC). Diese kann sowohl experimentell gemessen oder anhand semi‐empirischer mathematischer Modelle berechnet werden. Die bestehenden Modelle sind lediglich für weiche Stahlgüten gültig – Grenzformänderungskurven für hochfeste Stahlgüten bzw. Aluminiumlegierungen können auf diese Weise nicht vorhergesagt werden. Aus diesem Grund beinhaltet dieser Beitrag die Vorstellung einer allgemeingültigen semi‐empirisch basierten Berechnungsmethode für Grenzformänderungskurven, welche für sämtliche im Fahrzeugbau eingesetzten Blechwerkstoffe Gültigkeit besitzt. Diese semi‐empirische Methode basiert auf einer Korrelation zwischen Kennwerten aus dem uniaxialen Zugversuch und experimentell ermittelten Grenzformänderungen. Mit Hilfe dieser Methode ist es möglich, basierend auf den Erkenntnissen aus dem uniaxialen Zugversuch Grenzformänderungsdiagramme für drei Werkstoffklassen (weiche Tiefziehgüten, höher‐ und hochfeste Stahlblechwerkstoffe und Aluminiumlegierungen) vorherzusagen bzw. mit hinreichender Genauigkeit mathematisch zu berechnen.
Apathy may herald cognitive decline and dementia in Parkinson's disease
Authors: Dujardin Kathy , Sockeel Pascal , Delliaux Marie , Destée Alain , Defebvre Luc
Published: November 2009

Apathy is usually defined as a lack of motivation. It may occur as part of another disorder (notably depression and dementia) or as an isolated syndrome. In Parkinson's disease (PD), apathy is common and several studies have reported an association between this condition and more severe cognitive symptoms, such as executive dysfunction. However, this association has not been thoroughly investigated. The aim of this study (in nondepressed, nondemented PD patients) was to examine whether or not cognitive decline and/or dementia occurred more frequently in apathetic subjects than in nonapathetic subjects. Forty consecutive PD patients participated in the study (20 with apathy and 20 without). None of the subjects were either demented or depressed at the time of study entry. The patients' cognitive functions were extensively assessed twice: at study entry and after an 18‐month follow‐up period. At study entry, the apathetic PD patients had significantly lower global cognitive status and executive function scores than the nonapathetic subjects. After a median period of 18 months, the rate of conversion to dementia was found to be significantly higher in the apathetic group than in the nonapathetic group (8 of 20 and 1 of 20, respectively). Even in nondemented patients, the decrease over time in cognitive performance (mainly executive function but also memory impairment) was significantly greater in apathetic subjects than in nonapathetic subjects. These findings suggest that in nondemented, nondepressed PD patients, apathy may be a predictive factor for dementia and cognitive decline over time. © 2009 Movement Disorder Society
A facility reliability problem: Formulation, properties, and algorithm
Authors: Lim Michael , Daskin Mark S. , Bassamboo Achal , Chopra Sunil
Published: November 2009

Having a robustly designed supply chain network is one of the most effective ways to hedge against network disruptions because contingency plans in the event of a disruption are often significantly limited. In this article, we study the facility reliability problem: how to design a reliable supply chain network in the presence of random facility disruptions with the option of hardening selected facilities. We consider a facility location problem incorporating two types of facilities, one that is unreliable and another that is reliable (which is not subject to disruption, but is more expensive). We formulate this as a mixed integer programming model and develop a Lagrangian Relaxation‐based solution algorithm. We derive structural properties of the problem and show that for some values of the disruption probability, the problem reduces to the classical uncapacitated fixed charge location problem. In addition, we show that the proposed solution algorithm is not only capable of solving large‐scale problems, but is also computationally effective. © 2009 Wiley Periodicals, Inc. Naval Research Logistics, 2010
Age‐related changes in brain energetics and phospholipid metabolism
Authors: Forester Brent P. , Berlow Yosef A. , Harper David G. , Jensen J. Eric , Lange Nicholas , Froimowitz Michael P. , Ravichandran Caitlin , Iosifescu Dan V. , Lukas Scott E. , Renshaw Perry F. , Cohen Bruce M.
Published: November 2009

Evidence suggests that mitochondria undergo functional and morphological changes with age. This study aimed to investigate the relationship of brain energy metabolism to healthy aging by assessing tissue specific differences in metabolites observable by phosphorus (31P) MRS. 31P MRSI at 4 Tesla (T) was performed on 34 volunteers, aged 21–84, screened to exclude serious medical and psychiatric diagnoses. Linear mixed effects models were used to analyze the effects of age on phosphorus metabolite concentrations, intracellular magnesium and pH estimates in brain tissue. A significant age associated decrease in brain pH (−0.53% per decade), increase in PCr (1.1% per decade) and decrease in PME (1.7% per decade) were found in total tissue, with PCr effects localized to the gray matter. An increase in beta NTP as a function of age (1% per decade) approached significance (p = 0.052). There were no effects demonstrated with increasing age for intracellular magnesium, PDE or inorganic phosphate. This study reports the effects of healthy aging on brain chemistry in the gray matter versus white matter using 31P MRS measures of high energy phosphates, pH and membrane metabolism. Increased PCr, increased beta NTP (reflecting ATP) and reduced pH may reflect altered energy production with healthy aging. Unlike some previous studies of aging and brain chemistry, this study examined healthy, non‐demented and psychiatrically stable older adults and specifically analyzed gray‐white matter differences in brain metabolism. Copyright © 2009 John Wiley & Sons, Ltd.
An efficient coarse‐grained parallel algorithm for global–local multiscale computations on massively parallel systems
Authors: Rahul  , De Suvranu
Published: November 2009

The existing global–local multiscale computational methods, using finite element discretization at both the macro‐scale and micro‐scale, are intensive both in terms of computational time and memory requirements and their parallelization using domain decomposition methods incur substantial communication overhead, limiting their application. We are interested in a class of explicit global–local multiscale methods whose architecture significantly reduces this communication overhead on massively parallel machines. However, a naïve task decomposition based on distributing individual macro‐scale integration points to a single group of processors is not optimal and leads to communication overheads and idling of processors. To overcome this problem, we have developed a novel coarse‐grained parallel algorithm in which groups of macro‐scale integration points are distributed to a layer of processors. Each processor in this layer communicates locally with a group of processors that are responsible for the micro‐scale computations. The overlapping groups of processors are shown to achieve optimal concurrency at significantly reduced communication overhead. Several example problems are presented to demonstrate the efficiency of the proposed algorithm. Copyright © 2009 John Wiley & Sons, Ltd.
Novel toughened cyanate ester resin with good dielectric properties and thermal stability by copolymerizing with hyperbranched polysiloxane and epoxy resin
Authors: Zhou Cheng , Gu Aijuan , Liang Guozheng , Yuan Li
Published: November 2009

A novel toughened cyanate ester (CE) resin with good dielectric properties and thermal stability was developed by copolymerizing 2,2′‐bis(4‐cyanatophenyl)iso‐propylidene (BCE) with a combined modifier (HBPSiEP) made up of hyperbranched polysiloxane (HBPSi) and epoxy (EP) resin. HBPSi was synthesized through the hydrolysis of 3‐(trimethoxysilyl)propyl methacrylate. The effect of differing stoichiometries of HBPSiEP on the curing characteristics and performance of BCE resin is discussed. Results show that the incorporation of HBPSiEP can not only effectively promote the curing reaction of BCE, but can also significantly improve the toughness of the cured BCE resin. In addition, the toughening effect of HBPSiEP is greater than single EP resin. For example, the impact strength of modified BCE resin with 30 wt% of HBPSiEP is 23.3 KJ/m2, which is more than 2.5 times of that of pure BCE resin, while the maximum impact strength of EP/BCE resin is about 2 times of pure BCE resin. It is worthy to note that HBPSiEP/BCE resins also exhibit improved thermal stability, dielectric properties, and flame retardancy, suggesting that the novel toughened CE resins have great potentiality to be used as a matrix for advanced functional composites or electronic packing resins. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and characterization of pH‐sensitive PAMPS/PVP nanogels in aqueous media
Authors: Atta Ayman M. , El‐Ghazawy Rasha A. M. , Farag Reem K. , Elsaeed Shymaa M.
Published: November 2009

A novel method for preparing poly (2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS) and poly (vinylpyrrolidone) (PVP) complex nanogels in PVP aqueous solution is discussed in this paper. The PAMPS/PVP complex nanogels were prepared via polymerization of 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) monomer in the presence of PVP nanoparticles which formed in water/acetone cosolvent in presence of N, N′‐methylenebisacrylamide (MBA) as a crosslinker, N, N, N′, N′‐tetramethylethylenediamine (TEMED) and potassium peroxydisulfate (KPS) as redox initiator system. The results of FTIR and 1H NMR spectra indicated that the compositions of PAMPS/PVP are consistent with the designed structure. TEM micrographs proved that PAMPS/PVP nanogels possess the spherical morphology before and after swelling. These PAMPS/PVP nanogels exhibited pH‐induced phase transition due to protonation of PAMPS chains. The properties of PAMPS/PVP nanogels indicate that PAMPS/PVP nanogels can be developed into a pH‐controlled drug delivery system. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis of aromatic poly(ether amide amide ether ketone ketone)s by electrophilic Friedel–Crafts solution polycondensation
Authors: Cai Mingzhong , Zhu Meihua , Qian Jiangping , Sun Yongfeng
Published: November 2009

A new monomer, N,N′‐bis(4‐phenoxybenzoyl)‐p‐phenylenediamine (BPBPPD), was prepared by the condensation of p‐phenylenediamine with 4‐phenoxybenzoyl chloride in N,N‐dimethylacetamide (DMAc). Novel aromatic poly(ether amide amide ether ketone ketone)s (PEAAEKKs) were synthesized by electrophilic Friedel–Crafts solution copolycondensation of BPBPPD with a mixture of terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC), over a wide range of TPC/IPC molar ratios, in the presence of anhydrous aluminum chloride and N‐methylpyrrolidone (NMP) in 1,2‐dichloroethane (DCE). The influences of reaction conditions on the preparation of polymers were examined. The polymers obtained were characterized by different physico–chemical techniques such as FT‐IR, Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), and wide angle X‐ray diffraction (WAXD). The polymers with 70–100 mol% IPC are semicrystalline and have remarkably increased Tgs over commercially available poly(ether ether ketone) (PEEK) and poly(ether ketone ketone) (PEKK) due to the incorporation of amide groups in the main chain. The polymers with 70–80 mol% IPC had not only high Tgs of 209–213°C, but also moderate Tms of 339–348°C, which are suitable for melt processing. The polymers with 70–80 mol% IPC had tensile strengths of 107.5–109.8 MPa, Young's moduli of 2.53–2.69 GPa, and elongations at break of 9–11% and exhibited high thermal stability and good resistance to organic solvents. Copyright © 2009 John Wiley & Sons, Ltd.
The maternal age‐specific live birth prevalence of trisomies 13 and 18 compared to trisomy 21 (Down syndrome)
Authors: Savva George M. , Walker Kate , Morris Joan K.
Published: November 2009

Objective

To estimate the maternal age‐specific live birth prevalence (in the absence of prenatal diagnosis and selective termination) of trisomy 13 (Patau syndrome) and trisomy 18 (Edwards syndrome) and compare it with that of trisomy 21 (Down syndrome).

Methods

Records of prenatal and postnatal diagnoses from seven UK regional congenital anomaly registers and two Australian registers covering 4.5 million births included 975 diagnoses of trisomy 13 and 2254 of trisomy 18. Prevalence at birth in the absence of prenatal diagnosis and selective termination was calculated by adjusting for prenatally diagnosed pregnancies that were terminated according to their likelihood of surviving to term.

Results

The live birth prevalence in the absence of prenatal screening and selective termination in England and Wales from 1997 to 2004 was 1.4 (95% CI: 1.2–1.6) per 10 000 births for trisomy 13 and 2.3 (95% CI: 2.1–2.5) for trisomy 18. It has increased since 1989–1996, by 13% for trisomy 13 and 25% for trisomy 18. These increases are consistent with those predicted due to increases in maternal age.

Conclusion

This study provides the first estimates of maternal age‐specific prevalence of trisomies 13 and 18 for women aged 16–45. Copyright © 2009 John Wiley & Sons, Ltd.
The complete three‐vessel view in prenatal detection of congenital heart defects
Authors: Tongsong Theera , Tongprasert Fuanglada , Srisupundit Kasemsri , Luewan Suchaya
Published: November 2009

Objective

To evaluate the effectiveness of the complete three‐vessel view (c3VV) in assessment of fetuses with prenatally diagnosed congenital heart defects (CHD).

Methods

Fetuses with prenatal suspicion of CHD were prospectively recruited into the study. All examinations included a c3VV for assessment of abnormalities in alignment, arrangement, vessel size, number of vessels, aortic arch sidedness and color flow mapping. Definite diagnoses of CHD were based on neonatal cardiologic exams or postnatal autopsy.

Results

Of 106 consecutive fetuses with CHD, 75 were shown to have at least one abnormality on the c3VV, a detection rate of 70.8%. When septal wall defects were excluded, the detection rate increased to 89%. All cases of transposition of great arteries (TGA), aortic stenosis, pulmonary stenosis, truncus arteriosus and ductal aneurysm showed abnormal c3VV. Additionally, abnormal c3VV was also visualized in most cases of double outlet right ventricle (DORV), Ebstein's anomaly and tricuspid atresia. Among the 75 fetuses with congenital heart defects detected at c3VV, some defects had several abnormalities visualized at c3VV. Of interest, two vessels on the c3VV were seen in all five cases of TGA, in all three cases of truncus arteriosus and in one‐third of DORV cases.

Conclusion

This prospective descriptive study demonstrates that the c3VV has high detection rate in identifying clues for the presence of CHD, especially when excluding septal wall defects. Thus, c3VV could probably be used as part of routine screening for CHD. Copyright © 2009 John Wiley & Sons, Ltd.
First trimester maternal serum pregnancy‐specific beta‐1‐glycoprotein (SP1) as a marker of adverse pregnancy outcome
Authors: Pihl Kasper , Larsen Torben , Laursen Inga , Krebs Lone , Christiansen Michael
Published: November 2009

Objective

To establish the first trimester levels of pregnancy‐specific beta‐1‐glycoprotein (SP1) in pregnancies with adverse outcome. Furthermore, to determine the screening performance for adverse outcome using SP1 alone and in combination with other first trimester markers including proMBP and PAPP‐A.

Methods

A case‐control study was conducted in a primary hospital setting. The SP1 concentration was measured in first trimester maternal serum in pregnancies with small‐for‐gestational age fetuses (SGA) (n = 150), spontaneous preterm delivery (n = 88), preeclampsia (n = 40) and in controls (n = 500). Concentrations were converted to multiples of the median (MoM) in controls and groups were compared using Mann–Whitney U‐test. Logistic regression analysis was used to determine significant factors for predicting adverse pregnancy outcome. Screening performance was assessed using receiver operating characteristic (ROC) curves.

Results

The SP1 MoM median was significantly reduced in cases with SGA (0.76 MoM, p < 0.0005) and spontaneous preterm delivery (0.77 MoM, p < 0.0005) whereas no alteration was found in cases with preeclampsia (0.94 MoM, p = 0.723). A significant correlation (r = 0.217) between log10(SP1 MoM) and the birth weight percentile was found in the SGA group. Screening performance was only slightly improved when SP1 was combined with PAPP‐A or proMBP.

Conclusion

SP1 is a first trimester maternal serum marker of SGA and preterm delivery. Copyright © 2009 John Wiley & Sons, Ltd.
Polymer nanocomposites reinforced with multi‐walled carbon nanotubes for semiconducting layers of high‐voltage power cables
Authors: Jeong Kwang‐Un , Lim Jee Young , Lee Jong‐Young , Kang Seong Lak , Nah Changwoon
Published: November 2009

Polymer nanocomposites reinforced with multi‐walled carbon nanotubes (MWCNTs) have been newly introduced for semiconducting layers of high‐voltage electrical power cables. Homogeneity of the MWCNT‐reinforced polymer nanocomposites was achieved by solution mixing, and their mechanical, thermal and electrical properties were investigated depending on the type of polymer. By changing the polymer matrix, the volume resistance of the MWCNT‐reinforced polymer nanocomposites could be varied by more than four orders of magnitude. Through systematic experiments and analysis, two possible factors affecting the volume resistance were found. One is the degree of crystallinity of the polymer used and the other is the change of MWCNT morphology under strain. By increasing the degree of crystallinity above a certain level, the volume resistance linearly increased. The MWCNTs embedded in the nanocomposites gradually protruded through the surface on stretching the sample and reversibly returned back to the original positions at a relatively small strain (below 20%). Based on the criteria of tensile properties and volume resistance, a poly[ethylene‐co‐(ethyl acrylate)]/MWCNT nanocomposite was selected as the best candidate for the semiconducting layers of high‐voltage electrical power cables. Copyright © 2009 Society of Chemical Industry
Measurement and repeatability of interrupter resistance in unsedated newborn infants
Authors: Adams A.M. , Olden C. , Wertheim D. , Ives A. , Bridge P.D. , Lenton J. , Seddon P.
Published: November 2009

Interrupter resistance (Rint) is a useful measure of airway caliber in young children, but has not been well characterized in infants—in whom there are concerns about the accurate measurement of driving pressure. This study aimed to assess the feasibility and repeatability of measuring Rint in unsedated newborn infants, and to explore alternative algorithms for calculating driving pressure. Rint measurement was attempted in 28 healthy term newborn infants during natural sleep using the MicroRint device. Paired Rint measurements were achieved in 24 infants, but after screening of waveforms only 15 infants had at least 5 technically acceptable waveforms on both measurements. Rint values obtained were comparable with reported values for airflow resistance in newborns using other methods. However, the repeatability coefficient (CR) was much higher than reported values in preschool children using standard back‐extrapolation algorithms, with CR 2.47 KPa L−1 sec (unscreened) and 2.93 KPa L−1 sec (screened). Other algorithms gave only marginally better repeatability, with all CR values over 50% of the mean Rint value. Using current commercially available equipment, Rint is too poorly repeatable to be a reliable measurement of airflow resistance in newborn infants. Lower deadspace equipment is needed, but anatomical and physiological factors in the infant are also important. Pediatr Pulmonol. 2009; 44:1168–1173. © 2009 Wiley‐Liss, Inc.
Reference values for the 6‐min walk test in healthy children aged 6–12 years
Authors: Priesnitz Camila Varella , Rodrigues Geneviève Horak , da Silva Stumpf Carolina , Viapiana Giovana , Cabral Cristina Posteraro , Stein Renato Tetelbom , Marostica Paulo José Cauduro , Donadio Márcio Vinícius Fagundes
Published: November 2009

Objective

To establish reference values for the 6‐min walk test in healthy children and adolescents aged 6–12 years.

Methods

This cross‐sectional, prospective study selected healthy children and adolescents aged 6–12 years, at three elementary schools in Porto Alegre. The anthropometric data of all the individuals were evaluated and two 6‐min walk tests were performed. Based on this, a reference equation was generated, and the test reproducibility was evaluated.

Results

One hundred eighty‐eight children (92 boys) performed the test. Pearson correlation showed that age (r = 0.51), height (r = 0.49), difference in heart rate before and after the test (dif. HR) (r = 0.30), and weight (r = 0.29) were significantly correlated with the distance covered in 6 min. The best multiple regression model included these four variables resulting in the following equation: 145.343 + [11.78 × age (years)] + [292.22 × height (m)] + [0.611 × dif. HR (bpm)] − [2.684 × body weight (kg)]. The intraclass correlation coefficient confirmed the reproducibility among tests.

Conclusion

The reference equation for the 6‐min walk test was generated and the distance covered is influenced by age, height, difference in heart rate before and after the test, and body weight. Pediatr Pulmonol. 2009; 44:1174–1179. © 2009 Wiley‐Liss, Inc.
HRCT and pulmonary function tests in monitoring of lung involvement in juvenile systemic sclerosis
Authors: Panigada Serena , Ravelli Angelo , Silvestri Michela , Granata Claudio , Magni‐Manzoni Silvia , Cerveri Isa , Dore Roberto , Tomà Paolo , Martini Alberto , Rossi Giovanni A. , Sacco Oliviero
Published: November 2009

Objective

To investigate the role of high‐resolution computed tomography (HRCT) and pulmonary function tests (PFTs) in staging pulmonary involvement in juvenile systemic sclerosis (JSS).

Methods

Clinical charts of 17 JSS patients (pts) were reviewed and high‐resolution CT (HRCT) scans and PFTs performed at first and last visit were examined. Forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC) and carbon monoxide diffusing capacity [DL(CO)] were measured (% pred. values) while HRCT changes were graded according to the Schurawitzki method (min–max score: 0–18).

Results

At initial assessment, 10 pts (58.8%) had pulmonary involvement (HRCT score >0 and/or PFTs <80% pred. values). PTFs abnormalities were consistent with a restrictive defect, with low FEV1, FVC and DL(CO) values and normal FEV1/FVC ratio. At first visit HRCT scores were inversely correlated with FEV1 (r = −0.75; P = 0.02), FVC (r = −0.685; P = 0.035), and DL(CO) values (r = −0.71; P = 0.03), but not with the FEV1/FVC ratio (r = −0.36; P = 0.31). Stronger inverse correlations were detected at last visit (median time interval: 4.3 years; min–max: 1–10 years) between HRCT and FEV1 (r = −0.86; P = 0.002), FVC (r = −0.79; P = 0.009) and DL(CO) (r = −0.79; P = 0.009), but not with the FEV1/FVC ratio (r = −0.33; P = 0.35). Changes in HRCT scores between first and last visit were correlated with changes in FEV1 (r = −0.74; P = 0.02), FVC (r = −0.81; P = 0.007), but not in DL(CO) values (r = 0.07;P = 0.84). At the last visit, of the 10 pts with pulmonary involvement at initial assessment 5 showed worsening of lung involvement and 5 either no significant changes in PFTs and HRCT or mild improvement.

Conclusions

PFTs, namely lung volumes, represent a reliable “monitoring” tool in children with JSS to identify pts that need to undergo an HRCT to rule out initial pulmonary involvement and to monitor the course of ILD over time. The weaker clinical value of DL(CO) may relate to poor lung function technique in some younger children. Pediatr Pulmonol. 2009; 44:1226–1234. © 2009 Wiley‐Liss, Inc.