bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of career colleges: Implications for serving racial and ethnic minority students
Authors: Heitner Keri , Sherman Kenneth C.
Published: October 2011

Career colleges may have an important role in addressing the educational needs of underrepresented racial and ethnic groups in higher education, such as African Americans, Hispanics, and Native Americans/Alaska Natives. This study focused on examining the extent to which career colleges meet the needs of these ethnic racial and minority students in states with the highest educational needs through analysis of publicly available data from NCHEMS, the Educational Needs Index, the American Community Survey, and College Navigator (IPEDS) on a sample of 114 for‐profit career colleges and 40 public/not‐for‐profit colleges. Racial/ethnic categories corresponded to categories reported in the IPEDS dataset. Career colleges outperformed other colleges in graduating students from these racial and ethnic minority backgrounds. Career colleges successful at enrolling, retaining, and/or graduating students from one racial or ethnic minority group appear to benefit students who are members of other racial or ethnic minority groups. Students may see that members of another racial or ethnic minority group can succeed in higher education and think that they can succeed, too. The results suggest narrowly focused diversity efforts on specific racial or ethnic student subpopulations may derive benefit across multiple subpopulations of students from racial and ethnic minority groups.
Raman spectroscopy of natural cordierite at high water pressure up to 5 GPa
Authors: Likhacheva Anna Yu. , Goryainov Sergey V. , Krylov Aleksandr S. , Bul'bak Taras A. , Prasad Pinnelli S. R.
Published: October 2011

The high‐pressure behaviour of cordierite, a widespread ring aluminosilicate with channels incorporating fluid compounds (H2O, CO2), is characterized by the absence of phase transitions up to 2.5 GPa. However, the distortion of the ring tetrahedra observed previously at 2.3 GPa is supposed to introduce a phase transition at higher pressure, which has not been checked so far. This work presents a high‐pressure Raman spectroscopic study of natural cordierite compressed in water medium up to 4.7 GPa in a diamond anvil cell. At P > 4 GPa, a disordering of both the framework and intrachannel H2O subsystem is apparent from significant broadening of Raman peaks and the evolution of short‐range order parameters. This is followed by abrupt shifts of the framework and O–H stretching modes at about 4.5 GPa, indicating a first‐order phase transition. Its reversibility is seen from the recovery of the initial spectrum at P < 3 GPa. The shift amplitudes of different framework modes indicate the predominance of distortion over contraction of the framework polyhedra upon this transition. The disordering of the H2O subsystem in the high‐pressure phase is likely a consequence of distortion of the channel‐forming framework elements, which is supposed to be a driving force of this transition. Copyright © 2011 John Wiley & Sons, Ltd.
Calibration of berlinite (AlPO4) as Raman spectroscopic pressure sensor for diamond‐anvil cell experiments at elevated temperatures
Authors: Watenphul Anke , Schmidt Christian
Published: October 2011

Changes in the band position of the 462 and the 1111 cm–1 A1 modes of berlinite (AlPO4) with temperature and pressure were determined in situ to 500°C and to 10 GPa using Raman spectroscopy and diamond‐anvil cells. These bands shift in opposite directions with pressure and, likewise, with temperature. At a known temperature, the relative difference of both band positions (Δν)P,T can therefore be used as a pressure gauge that does not require calibration of the spectrometer. At ambient pressure, the observed temperature dependence of this relative difference of the line positions is very close to linear and can be described by (Δν)T, 0.1 MPa (cm–1) = 0.0181 T – 0.46 where 23 ≤ T (°C) ≤ 500. Along the 23°C isotherm to 10 GPa, pressure and relative wavenumber difference (Δν)P, 23°C are related by the equation P (GPa) = 0.00083 [(Δν)P, 23°C]2 – 0.062 (Δν)P, 23°C. Both equations can be combined to determine pressures at higher temperatures under the assumption that the change in (Δν)P,T with pressure is insensitive to temperature. Copyright © 2011 John Wiley & Sons, Ltd.
Improved performance of surface‐enhanced Raman scattering on silver substrates prepared in nitric acid solutions
Authors: Mai Fu‐Der , Hsu Ting‐Chu , Liu Yu‐Chuan , Yang Kuang‐Hsuan
Published: October 2011

In this work, we propose a new electrochemical method to prepare surface‐enhanced Raman scattering (SERS)‐active silver substrates in nitric acid solutions. Experimental results indicate that the SERS intensity of adsorbed Rhodamine 6G (R6G) can be significantly increased, as compared with that of R6G adsorbed on a SERS‐active Ag substrate prepared by an electrochemical method in a chloride‐containing solution, which was generally employed in the literature. Moreover, the SERS of R6G on the newly developed substrate (prepared in a nitric acid solution) still performs well at a high temperature of 250 °C. However, the enhancement capability of the SERS‐active substrate prepared in a chloride‐containing solution is seriously destroyed at temperatures higher than 150 °C. Further investigations indicate that the oxidation states of roughened Ag substrates prepared in nitric acid solutions under different experiment conditions have less influence on the corresponding SERS performances. Instead, different surface morphologies of roughened Ag substrates and different contents of nitrogen‐containing dopping ions on the roughened Ag substrates demonstrate significant effects on the corresponding SERS performances. Copyright © 2011 John Wiley & Sons, Ltd.
Kinetics and mechanism of reaction between zirconium‐lactate and pentane‐2,4‐dione in excess lactate
Authors: Ghosh Rozi , Banerjee Rupendranath , Sarkar Diptabhas
Published: October 2011

The kinetics of the reaction of pentane‐2,4‐dione (HA) with ZrIV has been studied at 25.0°C in an excess lactate (L−) media. The equilibrium reaction was found to be: Zr2L6+HA⇌HL+Zr2AL5. The equilibrium was approached from either direction and a plausible mechanism has been proposed with kinetic constants, but individual reactivities of the keto and the enol tautomers of pentane‐2,4‐dione could not be apportioned. However, it was found that both the uncatalyzed and acid‐catalyzed paths contribute to the reverse reaction. But 2‐thenoyltrifluoroacetone (HT) forms a stronger chelate with ZrIV, so its reaction with less reactive Zr2L5(OH2) could not be detected; reactivity of the more reactive Zr2L5(OH2)(OH) could be found. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 725–729, 2011
Mehr Serie anstatt Prototypen
Authors: Hasenauer Frank , Hesser Hans‐Jörg
Published: October 2011

Das Lasersintern von Prototypen kann heute als etabliert gelten. Daneben kommt die Serienproduktion mit diesem Herstellverfahren erst langsam in Fahrt. Dort gibt es allerdings ein weitaus größeres Marktpotenzial zu heben, vorausgesetzt, die Kunden können die Vorteile erkennen.
Efficient human fetal liver cell isolation protocol based on vascular perfusion for liver cell–based therapy and case report on cell transplantation
Authors: Gridelli Bruno , Vizzini Giovanni , Pietrosi Giada , Luca Angelo , Spada Marco , Gruttadauria Salvatore , Cintorino Davide , Amico Giandomenico , Chinnici Cinzia , Miki Toshio , Schmelzer Eva , Conaldi Pier Giulio , Triolo Fabio , Gerlach Jörg C.
Published: October 2011

Although hepatic cell transplantation (CT) holds the promise of bridging patients with end-stage chronic liver failure to whole liver transplantation, suitable cell populations are under debate. In addition to hepatic cells, mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) are being considered as alternative cell sources for initial clinical cell work. Fetal liver (FL) tissue contains potential progenitors for all these cell lineages. Based on the collagenase incubation of tissue fragments, traditional isolation techniques yield only a fraction of the number of available cells. We report a 5-step method in which a portal vein in situ perfusion technique is used for tissue from the late second trimester. This method results in the high viabilities known for adult liver vascular perfusion, addresses the low cell yields of conventional digestion methods, and reduces the exposure of the tissue to collagenase 4-fold. We used donated tissue from gestational weeks 18 to 22, which yielded 1.8 ± 0.7 × 109 cells with an average viability of 78%. Because HSC transplantation and MSC transplantation are of interest for the treatment of hepatic failure, we phenotypically confirmed that in addition to hepatic progenitors, the resulting cell preparation contained cells expressing typical MSC and HSC markers. The percentage of FL cells expressing proliferation markers was 45 times greater than the percentage of adult hepatocytes expressing these markers and was comparable to the percentage of immortalized HepG2 liver hepatocellular carcinoma cells; this indicated the strong proliferative capacity of fetal cells. We report a case of human FL CT with the described liver cell population for clinical end-stage chronic liver failure. The patient's Model for End-Stage Liver Disease (MELD) score improved from 15 to 10 within the first 18 months of observation. In conclusion, this human FL cell isolation protocol may be of interest for further clinical translation work on the development of liver cell–based therapies. Liver Transpl 18:226–237, 2012. © 2011 AASLD.
Measurement of fibrin concentration by fast field‐cycling NMR
Authors: Broche Lionel M. , Ismail Saadiya R. , Booth Nuala A. , Lurie David J.
Published: October 2011

The relaxation of 1H nuclei due to their interaction with quadrupolar 14N nuclei in gel structures is measured using fast field‐cycling NMR. This phenomenon called quadrupolar dips has been reported in different 1H‐14N bond‐rich species. In this study, we have studied quadrupolar dips in fibrin, an insoluble protein that is the core matrix of thrombi. Fibrin was formed by the addition of thrombin to fibrinogen in 0.2% agarose gel. T1‐dispersion curves were measured using fast field‐cycling NMR relaxometry, over the field range of 1.5–3.5 MHz (proton Larmor frequency), and were analyzed using a curve‐fitting algorithm. A linear increase of signal amplitude with increasing fibrin concentration was observed. This agrees with the current theory that predicts a linear relationship of signal amplitude with the concentration of contributing 14N spins in the sample. Interestingly, fibrin formation gave rise to the signal, regardless of crosslinking induced by the transglutaminase factor XIIIa. To investigate the effect of proteins that might be trapped in the thrombi in vivo, the plasma protein albumin was added to the fibrin gel, and an increase in the quadrupolar signal amplitude was observed. This study can potentially be useful for thrombi classification by fast field‐cycling MRI techniques. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
A preliminary theory of dark network resilience
Authors: Bakker René M. , Raab Jörg , Milward H. Brinton
Published: October 2011

A crucial contemporary policy question for governments across the globe is how to cope with international crime and terrorist networks. Many such “dark” networks—that is, networks that operate covertly and illegally—display a remarkable level of resilience when faced with shocks and attacks. Based on an in‐depth study of three cases (MK, the armed wing of the African National Congress in South Africa during apartheid; FARC, the Marxist guerrilla movement in Colombia; and the Liberation Tigers of Tamil Eelam, LTTE, in Sri Lanka), we present a set of propositions to outline how shocks impact dark network characteristics (resources and legitimacy) and networked capabilities (replacing actors, linkages, balancing integration and differentiation) and how these in turn affect a dark network's resilience over time. We discuss the implications of our findings for policymakers. © 2011 by the Association for Public Policy Analysis and Management.
Use of fetal nuchal translucency in the first trimester to predict single‐gene disorders
Authors: Arigita Marta , Borrell Antoni , Mula Raquel , Sanchez Aurora , Milà Montse , Gratacos Eduard
Published: October 2011

Objective

To assess the predictive value of fetal nuchal translucency (NT) measurement in the prenatal diagnosis of single‐gene disorders.

Methods

From January 1996 to December 2006, fetal NT was prospectively measured before chorionic villi sampling in 169 pregnancies at high risk for a single‐gene disorder at 11 to 13 weeks of pregnancy.

Results

No differences were found between the 63 affected and 116 nonaffected fetuses in pregnancy demographic characteristics, in mean NT measurements, expressed either in millimetres [1.8 (95% CI:1.6–1.9) vs 1.7 (95% CI:1.6–1.8)] or in multiples of the median [1.19 (95%CI: 1.04–1.35) vs 1.14 (95%CI: 1.05–1.23)], or in median NT. The percentage of increased NT above the 95th percentile was similar for affected (9.5%) and nonaffected (11.2%) fetuses.

Conclusion

Not all single‐gene disorders are associated with enlarged NT, therefore NT cannot be regarded as a generic marker for single‐gene disorder but only for a limited number of these conditions. Copyright © 2011 John Wiley & Sons, Ltd.
Prenatal genetic diagnosis using microarray analysis in fetuses with congenital heart defects
Authors: Schmid Maximilian , Stary Susanne , Blaicher Wibke , Gollinger Michaela , Husslein Peter , Streubel Berthold
Published: October 2011

Objective

To evaluate the use of microarray analysis as a tool for the detection of submicroscopic chromosomal aberrations in prenatal diagnosis.

Methods

Twelve consecutive singleton fetuses with congenital heart defects but normal karyotype and normal fluorescence in situ hybridization results for the DiGeorge region were examined for chromosomal aberrations by genomic microarray analysis. Results were confirmed by fluorescence in situ hybridization and quantitative real time‐polymerase chain reaction.

Results

At 1 Mb resolution, potentially causal copy number variations were identified in 3 out of 12 fetuses (25%) comprising a 9 Mb q terminal deletion on chromosome 15, a 3.5 Mb duplication in the critical region for the Potocki–Lupski syndrome on chromosome 17 and a mosaic trisomy 7. At higher resolution, aberrations with uncertain significance were identified in a further three cases (25%).

Conclusion

In our study, the application of microarray analysis in prenatal testing proved to be a valuable tool for the identification of submicroscopic chromosomal aberrations where conventional cytogenetic methods failed. Selection of appropriate resolution was found to be critical to obtain reliable, diagnostically conclusive data. © 2011 John Wiley & Sons, Ltd.
Perinatal outcome of sacrococcygeal teratoma
Authors: Lee Mi‐Young , Won Hye‐Sung , Hyun Min‐Kyung , Lee Hee‐Young , Shim Jae‐Yoon , Lee Pil‐Ryang , Kim Ahm
Published: October 2011

Objective

To evaluate the outcome in a cohort of fetuses with isolated sacrococcygeal teratoma (SCT) in relation to the need for in utero intervention.

Methods

We retrospectively analyzed a cohort of fetuses prenatally diagnosed with SCT between September 2000 and December 2010. Postnatal outcomes were evaluated in relation to the need for intervention in utero by reviewing medical records.

Results

Of the 35 fetuses diagnosed with SCT during the study period, ten were lost to follow up and three had been misdiagnosed as SCT. Among the remaining 22 cases, in utero interventions were performed in eight, including radiofrequency ablation (RFA) in four, shunt operations in two, RFA plus cyst aspiration in one, and RFA with subsequent shunt operation in one. Tumors of cases undergoing in utero intervention were larger with rapidly growing, more frequently vascular, and with associated polyhydramnios or cardiomegaly. The rate of preterm births was higher in the cases that underwent interventions compared with those that did not (7/8 vs 2/14). Only one tumor showed regression after RFA while the other seven increased in size. Median tumor size at birth was significantly larger in the intervention group than in the nonintervention group (136 mm vs 80 mm). The neonatal survival rate was 6/8 for the prenatal intervention group and 14/14 for the nonintervention group. Resection of SCT was required in all neonates. The most common complication after postnatal surgery was fecal incontinence.

Conclusion

Fetuses with SCT undergoing in utero intervention have worse prognostic features, yet their neonatal outcome is similar to those of fetuses not requiring intervention. Copyright © 2011 John Wiley & Sons, Ltd.
Health care supply and county‐level variation in attention‐deficit hyperactivity disorder prescription medications
Authors: Bruckner Tim A. , Hodgson Ashley , Mahoney Chris Brown , Fulton Brent D. , Levine Peter , Scheffler Richard M.
Published: October 2011

Purpose

Although much literature reports small‐area variation in medication prescriptions used to treat attention‐deficit hyperactivity disorder (ADHD), scant research has examined factors that may drive this variation. We examine, across counties in the USA, whether the use of prescription medications to treat ADHD varies positively with supply‐side healthcare characteristics.

Methods

We retrieved annual prescription data for ADHD medications in 2734 US counties from a nationally representative sample of 35 000 pharmacies in 2001–2003. We used a county‐level, multivariable fixed effects analysis to estimate the relation between annual changes in healthcare supply and ADHD medication prescriptions. Methods controlled for time‐invariant factors unique to each county as well as ADHD prevalence.

Results

From 2001 to 2003, retail prescription purchases for ADHD medications increased 33.2%. In the multivariable analysis, ADHD medication prescriptions move positively with an increase in the concentration of total physicians. In addition, ADHD medication prescriptions move inversely with changes in the percentage of non‐Hispanic Black population.

Conclusions

Supply‐side healthcare factors may contribute to the rise from 2001 to 2003 in ADHD medication prescriptions. This finding warrants attention because it implies that the relative capacity of the healthcare system may influence population prescription rates. We encourage further exploration of the contribution of the supply‐side of the healthcare market to secular changes in ADHD medication prescriptions. Copyright © 2011 John Wiley & Sons, Ltd.
Oxidative Stress—Cause or consequence of male genital tract disorders?
Authors: Kullisaar Tiiu , Türk Silver , Punab Margus , Mändar Reet
Published: October 2011

BACKGROUND

Inflammatory prostatitis patients are characterized by oxidative stress (OxS) at local and systemic levels. Less is known about the occurrence of OxS in the case of other frequent male genital tract disorders.

METHODS

The study included 196 men: controls (n = 28), asymptomatic inflammatory (NIH category IV) prostatitis patients (n = 21), non‐inflammatory (NIH category IIIb) chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) patients (n = 48), inflammatory (NIH category IIIa) CP/CPPS patients (n = 44), benign prostate hyperplasia (BPH) patients (n = 33), and patients with BPH and NIH IV category prostatitis (n = 22). In all subjects, 8‐isoprostanes (8‐EPI) in urine were determined by competitive enzyme‐linked immunoassay.

RESULTS

The levels of 8‐EPI were substantially higher in all diseased groups—inflammatory CP/CPPS (P < 0.001), non‐inflammatory CP/CPPS (P = 0.03), asymptomatic inflammatory prostatitis (AIP; P = 0.02), BPH (P = 0.007), and BPH + AIP (P = 0.014) in comparison with controls. Importantly, our study showed that OxS is also present in the case of NIH IIIb category prostatitis when the patients have just chronic pelvic pain but no inflammation in prostate‐specific materials, as well as in the patients with just lower urinary tract symptoms without pain or overt inflammation.

CONCLUSIONS

This study revealed that several male genital tract disorders—BPH and different forms of prostatitis (NIH categories IIIa, IIIb, and IV)—are tightly interconnected via OxS‐mediated pathways. Acknowledging OxS as an important pathogenesis mechanism of these diseases helps to open up new horizons for their treatment. Prostate 72:977–983, 2012. © 2011 Wiley Periodicals, Inc.
TGF‐β and stem cell factor regulate cell proliferation in the proximal stem cell niche
Authors: Salm Sarah , Burger Patricia E. , Wilson Elaine Lynette
Published: October 2011

BACKGROUND

Stem cells are located in specific regulatory environments termed niches, which modulate the survival and proliferation of the cells through a variety of both mitogenic and inhibitory cytokines. In the murine prostate, stem cells are located in the proximal region of prostatic ducts. We examined the regulation of murine prostate cells in the stem cell niche by transforming growth factor beta (TGF‐β) and stem cell factor (SCF).

METHODS

Prostate cells from the proximal and distal regions of prostatic ducts were cultured in the presence and absence of TGF‐β and SCF, both on collagen‐coated wells and in collagen gels. Cell growth on collagen was assessed by determining cell number. Cell growth in collagen gels was quantified by determining the number, size and complexity of prostatic ducts. The basal and luminal phenotype of the cells was determined by immunohistochemistry.

RESULTS

Endogenous TGF‐β inhibited proliferation and promoted differentiation of proximal cells towards a luminal phenotype. It also inhibited duct‐forming capacity and promoted differentiation of prostatic ducts towards a luminal phenotype. Addition of SCF enhanced proximal cell proliferation on collagen‐coated wells and duct formation in collagen gels. Proliferation was further increased by ablation of endogenous TGF‐β.

CONCLUSION

Proliferation and the basal/luminal cell composition of cells isolated from the proximal region of prostatic ducts, the stem cell niche, is regulated in part by opposing effects of SCF and endogenous TGF‐β. Prostate 72:998–1005, 2012. © 2011 Wiley Periodicals, Inc.
Effects of point mutations in pVHL on the binding of HIF‐1α
Authors: Domene Carmen , Illingworth Christopher J. R.
Published: October 2011

The von Hippel‐Lindau tumor suppressor protein (pVHL) has an essential role in the regulation of the hypoxia response pathway in animal cells. Under normoxic conditions, the hypoxia‐inducible factor (HIF) undergoes trans‐4‐prolyl hydroxylation and is subsequently recognised by the β‐domain of pVHL, leading to the ubiquitination and degradation of HIF. Mutations of pVHL alter the binding of HIF. A subset of relevant clinically observed mutations to pVHL are thought to cause weaker binding of HIF‐1α and are associated with cancer and cardiovascular diseases. Here, we present computational studies analyzing the interaction of HIF with mutant forms of pVHL, describing at atomic detail the local structural reorganization caused by substitution of certain residues of pVHL. The results reveal that the canonical configuration in the wild‐type system is vital for the efficient functioning of the complex and that mutation of any of the residues implicated in the h‐bond network in the binding site disrupts HIF binding. Although the experimentally observed ordering of binding energies for mutants of Tyr98 is reproduced, our examination of a broader range of mutations does not support the hypothesis of a correlation between the degree of disruption of the pVHL/HIF‐1α interaction caused by a mutation and the phenotype with which the mutation is associated. We suggest that disruption of the binding interaction is one of many factors behind the manifestation of VHL disease. Proteins 2011. © 2012 Wiley Periodicals, Inc.
The specific binding of peptide ligands to cardiomyocytes derived from mouse embryonic stem cells
Authors: Li Zhuokun , Fan Jiusong , Zhao Wenxiu , Jin Lei , Ma Lan
Published: October 2011

Purification of pluripotent stem cell (PSC)‐derived cardiomyocytes is critical for the application of cardiomyocytes both in clinical and basic research. Finding a specific cell marker is a promising method for purifying induced cells. The present study employed phage display technology to search for particular cell markers that could bind specifically to PSC‐derived cardiomyocytes. After three rounds of biopanning, several peptides were obtained. The ELISA results show the no. 3 sequence peptide (QPFTTSLTPPAR), and other four sequences having a consensus motif [SS(Q)PPQ(S)], no. 9, 11, 14, and 10, have relatively high affinity and specificity to cardiomyocytes. Immunofluorescence confirmed that the selected peptides could bind specifically to the PSC‐derived cardiomyocytes. Competition tests with chemically synthesized peptides revealed the binding ability was caused by the peptide itself. Western blot analysis proved the phages were both bound to two 17 kDa cardiomyocyte membrane proteins and the no. 9 sequence showed a 55 kDa protein that was not observed in the no. 3 sequence. These results suggest that the selected peptides specifically target receptors on PSC‐derived cardiomyocyte membranes. The results will pave the way for further studies of cell surface markers and their applications, such as labeling, purification, and as vehicles for drug delivery. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
In silico predictions of 3D structures of linear and cyclic peptides with natural and non‐proteinogenic residues
Authors: Beaufays Jérôme , Lins Laurence , Thomas Annick , Brasseur Robert
Published: October 2011

We extended the use of Peplook, an in silico procedure for the prediction of three‐dimensional (3D) models of linear peptides to the prediction of 3D models of cyclic peptides and thanks to theab initiocalculation procedure, to the calculation of peptides with non‐proteinogenic amino acids. Indeed, such peptides cannot be predicted by homology or threading. We compare the calculated models with NMR and X‐ray models and for the cyclic peptides, with models predicted by other in silico procedures (Pep‐Fold and I‐Tasser). For cyclic peptides, on a set of 38 peptides, average root mean square deviation of backbone atoms (BB‐RMSD) was 3.8 and 4.1 Å for Peplook and Pep‐Fold, respectively. The best results are obtained with I‐Tasser (2.5 Å) although evaluations were biased by the fact that the resolved Protein Data Bank models could be used as template by the server. Peplook and Pep‐Fold give similar results, better for short (up to 20 residues) than for longer peptides. For peptides with non‐proteinogenic residues, performances of Peplook are sound with an average BB‐RMSD of 3.6 Å for ‘non‐natural peptides’ and 3.4 Å for peptides combining non‐proteinogenic residues and cyclic structure. These results open interesting possibilities for the design of peptidic drugs. Copyright © 2011 European Peptide Society and John Wiley & Sons, Ltd.
Investigation in Influence of Types of Polypropylene Material on Diffusion by Using Molecular Dynamics Simulation
Authors: Wang Zhi‐Wei , Wang Ping‐Li , Hu Chang‐Ying
Published: October 2011

Polypropylene (PP) and its copolymers are widely used in food packaging films and containers. This paper investigates the diffusion of limonene as a low molar mass compound through three types of polypropylene materials (PP‐H, PP‐B and PP‐R) by using the molecular dynamics method, evaluates the influence of types of polypropylene material on the diffusion behaviour of limonene and reveals the diffusion mechanism. The diffusion coefficients of limonene in PP‐H, PP‐B and PP‐R are obtained at 313K and 353K. The accessible free volumes for polymers PP‐H, PP‐B and PP‐R are calculated by using the probe radius rp = 0.09, 0.11, 0.128 and 0.209 nm, respectively. The results suggest that not only the amount of accessible free volume in PP‐R cell model is larger than that of PP‐H and PP‐B but also the free volume in PP‐R connects together to form some larger free volume clusters. The movements of the limonene molecules through the PP‐H, PP‐B and PP‐R cell models at different simulation time suggest that for a long time the limonene molecules squirm slowly in the polymer cell rather than jumping and that the hopping diffusion is not suitable to explain the diffusion of limonene in polypropylene. The movement trajectories of the limonene molecules in PP‐R indicate that the movements of limonene in PP‐R are more active than that in PP‐H and PP‐B. The paper reveals the diffusion dynamics process and microscopic mechanism of small molecules from different types of polypropylene. Copyright © 2011 John Wiley & Sons, Ltd.
High‐resolution simulation of a major West African dust‐storm: comparison with observations and investigation of dust impact
Authors: Kocha C. , Lafore J.‐P. , Tulet P. , Seity Y.
Published: October 2011

This study focuses on the radiative impacts of dust on the thermodynamics and dynamics of a major Saharan dust‐storm that occurred between 7 and 15 March 2006. The implementation of a dust module within the convective‐scale operational model AROME permitted a 10‐day simulation at high resolution (5 km) over a large domain (6.5–30°N; 3°W–33°E). The model is able to represent most of the life cycle of this dust‐storm and of the principal dust sources. According to the comparison with a complete and comprehensive set of measurements obtained within the framework of the AMMA field campaign in 2006, the simulation succeeds in representing the main thermodynamic and radiative features of the storm both qualitatively and quantitatively. As compared with a simulation without the dust, the coupling with the dust module provides signatures of the storm that are in better agreement with radiation and temperature observations. The intense heating in the core of the dust plume (more than 2°C) resulted in a large vertical dipole of potential vorticity anomaly with higher values at low levels and weaker values at mid levels, either in the lower and the upper part of the dust plume respectively. This shows that the coupling with dust reinforces the intensity of the cold extratropical outbreak with more ascent at the cold front, more cyclonic convergence near the surface, and more anticyclonic divergence aloft. Also, the subsidence is increased at the rear of the outbreak with more northerly winds. A major result is the acceleration of the easterly along‐front flow (∼3 m s−1) at low levels and in the African Easterly Jet, increasing the emission of dust and its westward long‐range transport. Copyright © 2011 Royal Meteorological Society
Multistep conformational interconversion mechanism of cyclododecane. A simple and fast analysis using potential energy curves
Authors: Saavedra Edgardo J. , Andujar Sebastian A. , Suvire Fernando D. , Zamora Miguel A. , Freile Monica L. , Enriz Ricardo D.
Published: October 2011

An ab initio and Density Functional Theory (DFT) study of the conformational properties of cyclododecane was carried out. The energetically preferred equilibrium structures, their relative stability, and some of the transition state (TS) structures involved in the conformational interconversion pathways were analyzed from RHF/6‐31G(d), B3LYP/6‐31G(d,p) and B3LYP/6311++G(d,p) calculations. Aug‐cc‐pVDZ//B3LYP/6311++G(d,p) single point calculations predict that the multistep conformational interconversion mechanism requires 11.07 kcal/mol, which is in agreement with the available experimental data. These results allow us to form a concise idea about the internal intricacies of the preferred forms of cyclododecane, describing the conformations as well as the conformational interconversion processes in the conformational potential energy hypersurface. Our results indicated that performing an exhaustive analysis of the potential energy curves connecting the most representative conformations is a valid alternate tool to determine the principal conformational interconversion paths for cyclododecane. This methodology represents a satisfactory first approximation for the conformational analysis of medium‐ and large‐size flexible cyclic compounds. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012
Robust model‐based fault detection and isolation for nonlinear processes using sliding modes
Authors: Castillo Iván , Edgar Thomas F. , Fernández Benito R.
Published: October 2011

This paper proposes a robust fault detection and isolation system for nonlinear processes that can be formulated as differential algebraic equations. For open‐loop stable or closed‐loop stabilized systems that operate under strict nonlinear detectability conditions, a methodology to design a nonlinear state estimator based on sliding mode theory was proposed. The extended observer can handle both parameter estimation and parameters with uncertainties. As a result, the state estimator is able to follow the faulty system, detecting faults by examining changes in the controlled outputs with respect to setpoint and then probing variations in the parameters estimated. Once the fault has occurred, the isolation mechanism uses the information provided from the state estimator, generated from recovery actions in the presence of a fault. These differences from normal operation trends can be derived through statistical analysis and then can be used to identify faults. A steam generator system was used to validate this approach, where process faults were considered. The proposed robust fault detection and isolation method shows significant advantages when applied to nonlinear model systems with parameter uncertainties or with complex nonlinearities. The complex nonlinearities can be simplified with algebraic nonlinear functions that have bounded uncertainties in their parameters. Copyright © 2011 John Wiley & Sons, Ltd.
Improvement of PBO fiber surface and PBO/PPESK composite interface properties with air DBD plasma treatment
Authors: Wang Qian , Chen Ping , Jia Caixia , Chen Mingxin , Li Bin
Published: October 2011

The interface of fibrous composites is a key factor to the whole properties of the composites. In this study, the effects of air dielectric barrier discharge (DBD) plasma discharge power density on surface properties of poly(p‐phenylene benzobisoxazole) (PBO) fiber and the interfacial adhesion of PBO fiber reinforced poly(phthalazinone ether sulfone ketone) (PPESK) composite were investigated by several characterization methods, including XPS, SEM, signal fiber tensile strength, interlaminar shear strength, and water absorption. After the air DBD plasma treatment at a power density of 41.4 W/cm3, XPS analysis showed that some polar functional groups were introduced on the PBO fiber surface, especially the emergence of a new oxygen‐containing group (−O–C = O group). SEM observations revealed that the air DBD plasma treatment had a great influence on surface morphologies of the PBO fiber, while the signal fiber tensile strength results showed only a small decline of 5.9% for the plasma‐treated fiber. Meanwhile, interlaminar shear strength value of PBO/PPESK composite was increased to 44.71 MPa by 34.5% and water absorption of the composite decreased from 0.46% for the untreated specimen to 0.27%. The results showed that the air DBD plasma treatment can effectively improve the properties of the PBO fiber surface and the PBO/PPESK composite interface. Results obtained from the above analyses also showed that both the fiber surface and the composite interface performance would be reduced when an undue plasma discharge power density was applied. Copyright © 2011 John Wiley & Sons, Ltd.
Effects of RF power on BZN thin‐film etching in SF6/Ar using surface analysis
Authors: Dai L. P. , Zhang G. J. , Wang S. Y. , Zhong Z. Q. , Wang G.
Published: October 2011

Reactive ion etching (RIE) was used to etch bismuth zinc niobate (BZN) films in SF6/ Ar plasma as a function of radio frequency (RF) power. Within the RF power range of choice, the etch rate of BZN films increases with increasing RF power. However, when RF power exceeds 200 W, the etch rate of films appears to increase at a slower rate. The structural properties of the BZN films before and after etching were characterized using X‐ray diffraction. As‐deposited film shows a cubic pyrochlore structure with preferential (222) plane orientation, but all the films etched at different reactive ion etching powers exhibit preferential (400) plane orientation. With increasing RF power, the ZnF2 phase becomes evident. Also, the film surfaces before and after etching were analysed using XPS. Metal fluorides were found to remain on the surface, resulting in varying relative atomic percentages with RF power. Zn‐rich surfaces were formed because low‐volatile ZnF2 residues were difficult to remove. Bi and Nb can be removed easily through chemical reactions because of their high volatility, whereas Bi–F and Nb–F, which were thought to be present in the form of a metal oxyfluoride, can still be detected using the narrow scan spectra. RF power has an effect on etch reaction through different plasma densities and particle energies, thus resulting in varying compositions and element chemical binding states. RF power also has an effect on the removal of residues. The minimum value of F atomic concentration is achieved at 150 W. Copyright © 2011 John Wiley & Sons, Ltd.
Adaptive aspirations: performance consequences of risk preferences at extremes and alternative reference groups
Authors: Hu Songcui , Blettner Daniela , Bettis Richard A.
Published: October 2011

Goals or aspirations and their relationships to risk taking and performance are important issues in both psychology and strategic management. The concept of adaptive aspirations, as discussed in Cyert and March's Behavioral Theory of the Firm, has long been a topic of interest in both fields. Moreover, many studies in strategy have focused on risk and/or extreme performance. In the current paper, we build on earlier models of adaptive aspirations. We introduce into the models a new risk preference function that incorporates changes in risk preference at extremes of performance. Based on empirical studies and the managerial literature, we also introduce alternative strategies for setting reference groups. Simulations of the resulting models suggest important differences in outcomes from earlier studies and this invites further empirical investigation. These simulations also have significant implications for managerial goal setting. Copyright © 2011 John Wiley & Sons, Ltd.
Rational heuristics: the ‘simple rules’ that strategists learn from process experience
Authors: Bingham Christopher B. , Eisenhardt Kathleen M.
Published: October 2011

While much research indicates that organizational processes are learned from experiences, surprisingly little is known about what is actually learned. Using a novel method to measure explicit learning, we track the learned content of six technology‐based ventures from three diverse countries as they internationalize. The emergent theoretical framework indicates that firms learn heuristics. These heuristics have a common structure centered on opportunity capture and are learned in a specific developmental order. This results in a deliberately small, yet increasingly strategic, portfolio of heuristics. Broadly, we contribute to the psychological foundations of strategy by highlighting the rationality of heuristics as strategy, capability creation as the cognitive transition from novice to expert heuristics, and simplification cycling as a critical dynamic capability for sustaining competitive advantage. Copyright © 2011 John Wiley & Sons, Ltd.
Beginning secondary science teacher induction: A two‐year mixed methods study
Authors: Luft Julie A. , Firestone Jonah B. , Wong Sissy S. , Ortega Ira , Adams Krista , Bang EunJin
Published: October 2011

Those who study secondary science teachers are often concerned with preservice or in‐service teacher development. Science teacher educators have acknowledged that this focus is limited, as the induction years of beginning teachers are an important component of teacher development. This mixed methods study focuses on the induction years of beginning content specialists, with the intention of adding to the literature in this underexamined area. The secondary science teachers in this study were followed during their first and second year of teaching in order to understand the changes in their beliefs, pedagogical content knowledge (PCK) and practices as a group, and as they participated in different induction programs. Analysis by induction program revealed that first year teachers who participated in science specific induction programs strengthened their beliefs, PCK, and practices. By the end of the second year, regardless of program, most of the teachers shared similar beliefs and PCK. However, the teachers in the science specific induction programs continued to enact more interactive learning environments that had more investigations and laboratories than did their peers in the other induction programs. For those who work with beginning science teachers, this study suggests that the induction of science specialists is an important area of work. It also explores the complex process of induction, and calls for more research into how beginning secondary science teachers learn and what types of induction experiences can best support beginning science teachers. © 2011 Wiley Periodicals, Inc. J Res Sci Teach 48: 1199–1224, 2011
The politics of teaching evolution, science education standards, and Being a creationist
Authors: Long David E.
Published: October 2011

This paper analyzes recent research conclusions regarding biology teacher attitudes toward evolution, and the variable implementation of evolution in the high schools nationwide. Berkman and Plutzer (2010. Evolution, creationism, and the battle to control America's classrooms. New York: Cambridge University Press) conclude that due to a large portion of high school biology teachers compromising or downplaying evolution in the curriculum, the placement of evolution specific courses in biology teacher preparation programs will steer evolution deniers away from the field. In this paper, such arguments are situated in a larger historical and philosophical context of science education. By discussing recent sociological insight into the religiosity of education majors and education faculty, new questions are raised about student and teacher ontology, what this means for understanding science, the politics of science teacher education programs, and the epistemological and ethical limits of science education standards to dissolve Creationism. © 2011 Wiley Periodicals, Inc. J Res Sci Teach 49: 122–139, 2012
Diagnostic study and meta‐analysis of C‐reactive protein as a predictor of postoperative inflammatory complications after pancreatic surgery
Authors: Warschkow Rene , Ukegjini Kristjan , Tarantino Ignazio , Steffen Thomas , Müller Sascha A. , Schmied Bruno M. , Marti Lukas
Published: October 2011

Purpose

Although C‐reactive protein (CRP) can be measured by a standard blood test, its diagnostic value for distinguishing patients with inflammatory complications after pancreatic surgery from patients with normal postoperative inflammatory responses has not been adequately investigated. This study aimed to assess the diagnostic accuracy of CRP levels for the occurrence of postoperative inflammatory complications after pancreatic surgery.

Methods

Clinical data and CRP levels measured in 280 patients after pancreatic surgeries (performed between 1998 and 2010) until postoperative day 10 (POD 10) were retrospectively analyzed. Using the receiver operating characteristic method, diagnostic accuracy was evaluated by an area under the curve (AUC) analysis. Furthermore, the results of the present study were compared to previously published reports by applying diagnostic meta‐analysis techniques.

Results

The 30‐day mortality rate was 3.9% (95% CI 2.1—7.0%). Inflammatory complications occurred in 153 of 280 patients (54.6%; 95% CI 48.8—60.4%). On POD 4, the AUC was 0.67 (95% CI 0.58—0.76). The highest diagnostic accuracy was observed on POD 7 (AUC 0.77; 95% CI 0.68—0.85). In a diagnostic meta‐analysis that included two additional studies, the diagnostic sensitivity on POD 4 was 0.63 (95% CI 0.50—0.76), and the specificity was 0.79 (95% CI 0.71—0.88). The highest sensitivity occurred on POD 6 (0.75; 95% CI 0.68—0.82). Considerable statistical heterogeneity was observed in the analysis of PODs 3, 4 and 5.

Conclusion

According to this limited evidence, CRP levels had a low to moderate diagnostic accuracy. Large, blinded studies are warranted for a more precise estimation of CRP's diagnostic value.
Standard versus extended lymphadenectomy in radical pancreatoduodenectomy for ductal adenocarcinoma of the head of the pancreas
Authors: Nimura Yuji , Nagino Masato , Takao Sonshin , Takada Tadahiro , Miyazaki Koji , Kawarada Yoshifumi , Miyagawa Shuichi , Yamaguchi Akihiro , Ishiyama Shuichi , Takeda Yutaka , Sakoda Kourou , Kinoshita Taira , Yasui Kenzo , Shimada Hiroshi , Katoh Hiroyuki
Published: October 2011

Background

The value of pancreatoduodenectomy (PD) with extended lymphadenectomy for pancreatic cancer has been evaluated by many retrospective studies and 3 randomized controlled trials (RCT). However, the protocols used and the results found in the 3 RCTs were diverse. Therefore, a multicenter RCT was proposed in 1998 to evaluate the primary end point of long‐term survival and the secondary end points of morbidity, mortality and quality of life of patients undergoing standard versus extended lymphadenectomy in radical PD for pancreatic cancer.

Methods

From March 2000 to May 2003, 112 patients with potentially curable pancreatic head cancer were enrolled and intraoperatively randomized to a standard or extended lymphadenectomy group. No resected patients received any adjuvant treatments.

Results

A hundred and one eligible patients were analyzed. Demographic and histopathological characteristics of the two groups were similar. The mean operating time, intraoperative blood loss and number of retrieved lymph nodes were greater in the extended group, but the other operative results were comparable.

Conclusions

Although this multicenter RCT was conducted in a strict setting, extended lymphadenectomy in radical PD did not benefit long‐term survival in patients with resectable pancreatic head cancer and led to levels of morbidity, mortality and quality of life comparable to those found after standard lymphadenectomy.