bluuebunny/crossref_metadata_2025 huggingface dataset:
Computational homogenization for multiscale crack modeling. Implementational and computational aspects
Authors: Nguyen Vinh Phu , Lloberas‐Valls Oriol , Stroeven Martijn , Sluys Lambertus Johannes
Published: June 2011

A computational homogenization procedure for cohesive and adhesive crack modeling of materials with a heterogeneous microstructure has been recently presented in Computer Methods in Applied Mechanics and Engineering (2010, DOI:10.1016/j.cma.2010.10.013). The macroscopic material properties of the cohesive cracks are obtained from the inelastic deformation manifested in a localization band (modeled with a continuum damage theory) at the microscopic scale. The macroscopic behavior of the adhesive crack is derived from the response of a microscale sample representing the microstructure inside the adhesive crack. In this manuscript, we extend the theory presented in Computer Methods in Applied Mechanics and Engineering (2010, DOI:10.1016/j.cma.2010.10.013) with implementation details, solutions for cyclic loading, crack propagation, numerical analysis of the convergence characteristics of the multiscale method, and treatment of macroscopic snapback in a multiscale simulation. Numerical examples including crack growth simulations with extended finite elements are given to demonstrate the performance of the method. Copyright © 2011 John Wiley & Sons, Ltd.
Reducing child support debt and its consequences: Can forgiveness benefit all?
Authors: Heinrich Carolyn J. , Burkhardt Brett C. , Shager Hilary M.
Published: June 2011

As child support debt owed nationally persists at enormous levels, both noncustodial parents and the custodial families who are not receiving support suffer significant hardships, and states are forced to expend greater resources on collection and enforcement efforts. This paper presents findings from an evaluation of a demonstration program developed to help noncustodial parents with large child support debts reduce their debt while simultaneously increasing child support paid to families, through gradual forgiveness of arrears conditional on payment of current child support obligations. The evaluation employs a randomized experimental design, nonexperimental analyses using propensity score matching and multilevel modeling techniques, and focus groups and follow‐up interviews. Results show a pattern of effects that suggests individuals responded to the program as intended. State‐ and family‐owed child support debt balances decreased for program participants, and participants paid more toward their child support obligations and arrears and made more frequent child support payments. The study findings suggest promise for the effectiveness of this program model in reducing child support debt burdens and in increasing families' receipt of child support, and they also point to ways in which the implementation of the program might be improved. © 2011 by the Association for Public Policy Analysis and Management.
MiR‐17/106b seed family regulates p21 in Hodgkin's lymphoma
Authors: Gibcus Johan H. , Kroesen Bart‐Jan , Koster Roelof , Halsema Nancy , de Jong Debora , de Jong Steven , Poppema Sibrand , Kluiver Joost , Diepstra Arjan , van den Berg Anke
Published: June 2011

Hodgkin's lymphoma (HL) is a B cell‐derived lymphoma characterized by a minority of malignant Hodgkin Reed–Sternberg (HRS) cells that have lost their normal B cell phenotype. Alterations in the cell cycle and apoptosis pathways might contribute to their resistance to apoptosis and sustained cell cycle progression. A key player in both cell cycle arrest and apoptosis is CDKN1A, encoding p21$^{{\rm{waf/cip1}}}$ (p21). P21 is regulated by p53 and can function as a cell cycle inhibitor when in the nucleus or as an apoptosis inhibitor when localized in the cytoplasm. We observed expression of p53, p21 and p‐p21 in a variable number of HRS cells in 24 of 40 cases. Expression of miR‐17 and miR‐106a was detected in HRS cells of 10 HL cases. MiR‐17/106b seed family members, CDKN1A RNA and p21 protein levels were variable in HL cell lines. We showed effective targeting of the CDKN1A 3′ UTR by miR‐17/106b in HL cell lines in a luciferase reporter assay and up‐regulation of p21 protein levels upon anti‐miR‐17 treatment of KM‐H2 cells. Functional studies indicated a p21‐mediated G1 arrest after miR‐17/106b down‐regulation in KM‐H2, whereas no G1 arrest was observed for U‐HO1 and L428. This difference could not be explained by differences in the 3′ UTR, the cellular location of p21 or expression variation during cell cycle progression. A strong correlation was observed for the miR‐17/106b:CDKN1A ratio and the responsiveness to miR‐17 inhibition, ie a low ratio in KM‐H2 and an extremely high ratio in the two unresponsive HL cell lines. In conclusion, we show that miR‐17/106b regulates p21 protein levels in HL and that the effect of miR‐17/106b‐mediated inhibition depends on the miRNA : target gene ratio. Thus, in HL high miR‐17/106b expression contributes to a dysfunctional p53 pathway and thereby also to the malignant phenotype. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Risks, trust and knowledge: determinants of pregnant women's decisions regarding participation in a future Q fever screening and treatment program during a large epidemic in The Netherlands
Authors: Breteler Janna Klein , Oudhoff Jurriaan P. , Munster Janna M. , Aarnoudse Jan G. , van Steenbergen Jim E. , Beaujean Desirée J. M. A.
Published: June 2011

Objective

Contracting Q fever during pregnancy carries a risk of developing obstetric complications. The aim of this study was to gain insight into pregnant women's decisions regarding participation in a future Q fever screening and treatment program.

Methods

Pregnant women (N = 148) in Q fever high‐risk areas in The Netherlands were recruited via midwives' practices and via an online panel for a cross‐sectional questionnaire survey. The outcome measures included intention to participate in the program, Q fever exposure risk, perceived Q fever risk, trust in health professionals and authorities, disease‐related knowledge and additional outcome measures.

Results

Fifty‐six percent of the respondents intended to participate in the screening and treatment program. The sole determinant of a higher intended program uptake was a more positive appraisal of program efficacy and convenience. This appraisal was in turn associated with perceived risk and knowledge.

Conclusion

Women's appraisal of program efficacy and convenience, their disease‐related knowledge and perceived Q fever risk seem to be crucial for their intended program uptake. A successful implementation of a Q fever screening and treatment program may thus depend on the benefits and downsides of the program, and on securing that women are aware of the risks of the disease. Copyright © 2011 John Wiley & Sons, Ltd.
Targeted ultrasound examination and DNA testing for Noonan syndrome, in fetuses with increased nuchal translucency and normal karyotype
Authors: Bakker M. , Pajkrt E. , Mathijssen I. B. , Bilardo C. M.
Published: June 2011

Objective

To define sonographic criteria that may improve the prenatal diagnosis of Noonan syndrome by targeted DNA testing.

Methods

We searched our Fetal Medicine Unit records for all cases with a final diagnosis of Noonan syndrome. A literature review was undertaken to identify the sonographic features of Noonan syndrome fetuses. Information was pooled to define the most common features.

Results

In our database, we identified three cases of Noonan syndrome. The diagnosis was suspected prenatally in two of them. Thirty‐nine cases were identified in the literature. In the presented cases we show that suspicion of Noonan syndrome should arise when, after an increased nuchal translucency, ultrasound investigation in the second trimester shows a persistant nuchal fold (NF) or cystic hygroma in combination with at least one of the following features: hydrops fetalis, pleural effusion, cardiac anomalies, polyhydramnios or specific facial abnormalities.

Conclusion

Prenatal ultrasound findings in Noonan syndrome can be subtle and aspecific, but when specific characteristics are present additional targeted DNA analysis is indicated. Copyright © 2011 John Wiley & Sons, Ltd.
Preventing mucopolysaccharidosis type II (Hunter syndrome): PGD and establishing a Hunter (46, XX) stem cell line
Authors: Altarescu Gheona , Renbaum Paul , Eldar‐Geva Talia , Brooks Baruch , Varshaver Irit , Avitzour Mical , Margalioth Ehud J. , Levy‐Lahad Ephrat , Elstein Deborah , Epsztejn‐Litman Silvina , Eiges Rachel
Published: June 2011

Objectives

Preimplantation genetic diagnosis (PGD) enables the identification of affected embryos prior to implantation. We present for the first time three families in which either the oocytes or embryos obtained from female carriers of mutations in the iduronate‐2‐sulfatase (IDS) gene underwent PGD for mucopolysaccharidosis type II (Hunter syndrome). Furthermore, we report the first ever derivation of a Hunter's syndrome (46, XX) human stem cell line from embryos (HESC) carrying the IDS and oculocutaneus albinism type 2 mutations.

Methods

Combined polar body (PB) 1 and 2 or a single cell of a six‐ to eight‐cell embryo (blastomere) was used for genetic analysis by multiplex polymerase chain reaction assay using six microsatellite polymorphic markers flanking the gene and mutation.

Results

One couple underwent four PB‐PGD cycles, with birth of a healthy girl; the second couple with one PB‐PGD cycle had healthy twins; the third couple underwent seven cycles of double PGD for Hunter and Albinism syndrome with birth of healthy twins. One novel Hunter 46, XX HESC line was established displaying typical characteristics of HESC cells.

Conclusions

PGD is a reliable method to prevent pregnancy of children affected with Hunter syndrome. In addition, derived HESC can be further utilized for drug testing and better understanding of the pathogenesis of this syndrome. Copyright © 2011 John Wiley & Sons, Ltd.
Ultrasound detection rate of single umbilical artery in the first trimester of pregnancy
Authors: Lamberty Clarissa O. , de Carvalho Mário Henrique Burlacchini , Miguelez Javier , Liao Adolfo Wenjaw , Zugaib Marcelo
Published: June 2011

Objective

To determine accuracy of first trimester detection of single umbilical artery (SUA).

Methods

The number of vessels in the umbilical cord was examined in a prospective cohort of 779 singleton, low‐risk, unselected pregnancies, in the first (11–13 weeks) and second (17–24 weeks) trimesters, using both power and color Doppler and after delivery, by placental histopathologic exam. Concordance between first and second trimester findings to postnatal diagnoses was compared by calculating kappa coefficients.

Results

There was medium concordance between the findings in the first trimester and the postnatal diagnoses (kappa = 0.52) and high concordance (kappa = 0.89) for the second trimester scan. Sensitivity, specificity, positive and negative predictive values for the findings in the first trimester were 57.1, 98.9, 50.0 and 99.2% and for the second trimester were 86.6, 99.9, 92.9 and 99.7%.

Conclusion

Sensitivity and positive predictive value of first trimester scan to identify an isolated SUA in a prospective unselected population was poor. Diagnosis of isolated SUA as well as a definitive judgment about the presence of associated anomalies would still require a scan in the second trimester. Copyright © 2011 John Wiley & Sons, Ltd.
The role of three‐dimensional imaging reconstruction to measure the corpus callosum: comparison with direct mid‐sagittal views
Authors: Miguelote R. F. , Vides B. , Santos R. F. , Palha J. A. , Matias A. , Sousa N.
Published: June 2011

Objectives

To determine the accuracy of measuring the corpus callosum (CC) length in reconstructed mid‐sagittal views obtained by 3D multiplanar manipulations or volume contrast imaging in the C‐plane (VCI‐C) in comparison to measurements obtained by direct mid‐sagittal view.

Methods

Forty‐six normal fetuses were examined by 2D and 3D ultrasound between 23 and 32 weeks of gestation. Direct mid‐sagittal views were obtained by either the transabdominal or/and the transvaginal approach. 3D reconstructed mid‐sagittal views were obtained by either 3D multiplanar manipulations or VCI‐C. The CC length was measured in direct mid‐sagittal views and in 3D reconstructed mid‐sagittal views.

Results

One hundred and thirty ultrasound examinations were performed. In 118 cases (91%) it was possible to obtain both a direct and a 3D reconstructed mid‐sagittal view. Measurements of the CC length in direct mid‐sagittal views correlated significantly with the measurements in reconstructed mid‐sagittal views when the region underneath the comma‐shaped echogenic structure was measured, but correlated poorly when this echogenic structure was included.

Conclusions

Reconstructed mid‐sagittal views obtained by 3D multiplanar manipulations or by VCI‐C are valid approaches for measuring CC length. In these views the CC should be measured as the region underneath the comma‐shaped echogenic structure. Copyright © 2011 John Wiley & Sons, Ltd.
Detection rate of quadruple‐marker screening determined by clinical follow‐up and registry data in the statewide California program, July 2007 to February 2009
Authors: Kazerouni Niloufar Neely , Currier Robert J. , Flessel Monica , Goldman Sara , Hennigan Colin , Hodgkinson Christina , Lorey Fred , Malm Linda , Tempelis Corinna , Roberson Marie
Published: June 2011

Objective

To evaluate the efficiency of California's quadruple‐marker screening program and construct receiver‐operating characteristic (ROC) curves.

Methods

This study included the screening records of 552 941 women during July 2007 to February 2009. The screen‐positive women received clinical follow‐up services at state‐approved centers. We used the California Chromosome Defect Registry which includes clinical, laboratory, and demographic data from the prenatal diagnostic centers, cytogenetic laboratories, hospitals, and prenatal care providers. Risk calculations, screen‐positive rates (SPRs), detection rates (DRs) for chromosomal abnormalities, and 95% confidence intervals (95% CIs) were determined. ROC curves comparing the quadruple‐marker to triple‐marker screening were constructed.

Results

The DR and SPR for trisomy 21 (N = 827) during the quadruple‐marker time period were 75.7% (95% CI 72.8–78.6%) and 3.75% (95% CI 3.70–3.80%) compared with 77.4% (95% CI 75.0–79.7%) and 5.4% during the triple‐marker phase. The DRs were 78.2% (95% CI 75.0–81.4%) with ultrasound dating and 66.9% (95% CI 59.7–74.0%) for last‐menstrual‐period‐dated pregnancies. For trisomy 18, triploidy, and trisomy 13, the DRs were 84.3, 95.7, and 43.5%, respectively.

Conclusions

The DR for trisomy 21 in California's statewide quadruple‐marker screening is very similar to the Program's previously reported DR using triple‐marker screening. However, this was achieved at a lower SPR, demonstrating improved screening performance. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis and post‐polymerization modification of maleimide‐containing polymers by ‘thiol‐ene’ click and Diels–Alder chemistries
Authors: Hall Daniel J. , Van Den Berghe Helene M. , Dove Andrew P.
Published: June 2011

This mini‐review provides an introduction to the key work in the area of synthesis and post‐polymerization functionalization of maleimide‐functional polymers. The versatility and utility of the maleimide group in the efficient functionalization of polymers by both ‘thiol‐ene’ Michael addition and Diels–Alder cycloaddition chemistries are highlighted. Copyright © 2011 Society of Chemical Industry
Structural investigations and swelling behavior of 6FDA copolyimide thin films
Authors: Konietzny Roman , Barth Christoph , Harms Stephan , Raetzke Klaus , Koelsch Patrick , Staudt Claudia
Published: June 2011

The effects of swelling on chain distance, free volume size and orientation of functional groups of copolyimides containing carboxyl groups were examined using wide‐angle X‐ray diffraction (WAXD), positron annihilation lifetime spectroscopy (PALS) and Fourier transform infrared (FTIR) spectroscopy. A 2,3‐dimethylbenzothiophene/n‐dodecane mixture (0.3 wt%/99.7 wt%) was used as a swelling agent, as it is a binary model mixture to investigate membrane‐based desulfurization of kerosene. Thin film samples were prepared from copolyimide structures which had been synthesized via a polycondensation reaction of 4,4′‐hexafluoroisopropylidene di(phthalic anhydride), 3,5‐diaminobenzoic acid, 2,3,5,6‐tetramethyl‐1,4‐phenylenediamine and 2,4,6‐trimethyl‐1,3‐phenylenediamine. A relationship between a lower amount of 3,5‐diaminobenzoic acid present in the copolyimide backbone and a higher amount of solvent sorption in the film was found. This was attributed to the fact that the carboxyl groups on the polymer backbone can form hydrogen bonds, reducing sorption and swelling phenomena. PALS measurements for the different structures showed significantly smaller hole sizes for the free volume sites of the copolyimide containing fewer carboxyl groups. Although WAXD of film samples after time‐dependent swelling indicated that the chain distance initially decreased slightly, FTIR experiments using polarized light did not show any significant orientation changes in the polymer chains. Copyright © 2011 Society of Chemical Industry
Influence of reactive compatibilization on the structure and properties of PP/LDH nanocomposites
Authors: Lonkar Sunil P. , Therias Sandrine , Leroux Fabrice , Gardette Jean Luc , Singh Raj Pal
Published: June 2011

Polypropylene (PP)/layered double hydroxide (LDH) nanocomposites were prepared by the direct melt intercalation method using maleic anhydride grafted polypropylene (PP‐g‐MAH) as a reactive compatibilizer. The compatibilization effects provided by PP‐g‐MAH in different weight fractions and their influence on the structure and properties of the final nanocomposites were investigated. The interactions and structural morphology of the nanocomposites were examined by Fourier transform infrared spectroscopy, X‐ray diffraction and transmission electron microscopy. Thermal, mechanical and rheological properties of these nanocomposites were investigated as a function of compatibilizer concentration. The detailed morphological and X‐ray diffraction results revealed that the degree of LDH dispersion increases as the amount of PP‐g‐MAH increases. Study of the linear viscoelastic properties showed that the storage modulus G′ is very sensitive to the microstructure of the nanocomposite. The thermal properties of the nanocomposites were significantly influenced by the weight fraction of PP‐g‐MAH due to the shielding and nucleating effect of exfoliated layers. Both the tensile strength and modulus showed substantial improvements with increasing PP‐g‐MAH content, while the elongation at break substantially decreased, although the presence of PP‐g‐MAH somewhat improves these values. The overall results showed that 10 wt% of compatibilizer is optimum to achieve nanocomposites with better performance. Copyright © 2011 Society of Chemical Industry
Toughening of poly(propylene carbonate) by hyperbranched poly(ester‐amide) via hydrogen bonding interaction
Authors: Chen Lijie , Qin Yusheng , Wang Xianhong , Li Yuesheng , Zhao Xiaojiang , Wang Fosong
Published: June 2011

Poly(propylene carbonate) (PPC) is a biodegradable alternative copolymer of propylene oxide and carbon dioxide. As an amorphous polymer with lower glass transition temperature around 35 °C, PPC shows poor mechanical performance in that it becomes brittle below 20 °C and its dimensional stability deteriorates above 40 °C; thus toughening of PPC is urgently needed. Here we describe a biodegradable hyperbranched poly(ester‐amide) (HBP) that is suitable for this purpose. Compared with pure PPC, the PPC/HBP blend with 2.5 wt% HBP loading showed a 51 °C increase in thermal decomposition temperature and a 100% increase in elongation at break, whilst the corresponding tensile strength remained as high as 45 MPa and tensile modulus showed no obvious decrease. Crazing as well as cavitation was observed in the scanning electron microscopy images of the blends, which provided good evidence for the toughening mechanism of PPC. The intermolecular hydrogen bonding interaction confirmed by Fourier transform infrared spectral analysis proved to be the reason for the toughening phenomenon. Copyright © 2011 Society of Chemical Industry
Preparation of polybutene‐1/multiwall carbon nanotube composite by oxidation and limonene radical grafting and its characterization
Authors: Nakatani Hisayuki , Ogura Masashi , Yoshikawa Takanori , Miyazaki Kensuke , Okazaki Noriyasu , Terano Minoru
Published: June 2011

In this study, a novel preparation of a polybutene‐1 (PB) and multiwall carbon nanotube (MWNT) composite was achieved by a combination of PB autooxidation and a radical grafting reaction using an Nd2O3/dicumyl peroxide (DCP) radical initiator system with limonene. The autooxidation worked as an amplifier to produce more alkyl radical species in the grafting reaction, and the existence of the MWNTs and the limonene suppressed the side reaction. In addition, the existence of the limonene suppressed the oxidation of the MWNT surface. The composite obtained was assessed in comparison with a PB/MWNT composite and a composite of PB/MWNT modified by Nd2O3/DCP without limonene using some spectroscopic methods, optical and electron microscopes, a thermal analyzer and tensile testing. The novel preparation produced a well dispersed nanocomposite compared with the other preparations. The modified MWNT surface was tightly linked to the PB matrix, so that the tensile properties of the composite showed a dependence on MWNT content. Copyright © 2011 Society of Chemical Industry
Upper critical solution temperature switchable micelles based on polystyrene‐block‐poly(methyl acrylate) block copolymers
Authors: Can Aydin , Hoeppener Stephanie , Guillet Pierre , Gohy Jean‐François , Hoogenboom Richard , Schubert Ulrich S.
Published: June 2011

The solubility behavior of well‐defined poly(methyl acrylate) homopolymers as well as polystyrene‐block‐poly (methyl acrylate) block copolymers is discussed in this contribution. A solubility screening in ethanol–water solvent mixtures was performed in a high‐throughput manner using parallel turbidimetry revealing upper critical solution temperature behavior for poly(methyl acrylate). Moreover, the self‐assembly behavior of the block copolymers into micellar structures was investigated by dynamic light scattering (DLS), transmission electron microscopy (TEM), andcryo‐TEM revealing upper critical solution temperature switchability of the micelles, which was evaluated by DLS at different temperatures. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Poly(acrylic acid) is a common noncompetitive inhibitor for cationic enzymes with high affinity and reversibility
Authors: Tomita Shunsuke , Shiraki Kentaro
Published: June 2011

We have recently developed a versatile technique, complementary polymer pair system (CPPS), which enables switching the activity of diverse enzymes using anionic poly (acrylic acid) (PAAc) and cationic poly(allylamine) (PAA). To obtain a deeper understanding of CPPS, we investigated the manner by which PAAc inhibits cationic ribonuclease A, lysozyme, and trypsin. Studies of the enzyme kinetics showed that PAAc acts as a noncompetitive inhibitor for all these enzymes, and carries several potent enzyme binding sites (Ki ≈ 10−8 M). In addition, the inhibited enzymes were recovered by oppositely charged PAA. These data indicate the generality of CPPS, as only the surface charge and not the substrate binding site of the enzymes should be considered when determining a charged polymer as an inhibitor. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis and photovoltaic properties of two‐dimensional D‐A copolymers with conjugated side chains
Authors: Chen Dugang , Yang Yang , Zhong Cheng , Yi Zhengran , Wu Fei , Qu Li , Li Yu , Li Yongfang , Qin Jingui
Published: June 2011

Four novel two‐dimensional (2D) donor–acceptor (D‐A) type copolymers with different conjugated side chains, P1, P2, P3, and P4 (see Fig. 1), are designed and synthesized for the application as donor materials in polymer solar cells (PSCs). To the best of our knowledge, there were few reports to systematically study such 2D polymers with D‐A type main chains in this area. The optical energy band gaps are about 2.0 eV for P1–P3 and 1.67 eV for P4. PSC devices using P1–P4 as donor and [6,6]‐phenyl‐C61‐butyric acid methyl ester as acceptor in a weight ratio of 1:3 were fabricated and characterized to investigate the photovoltaic properties of the polymers. Under AM 1.5 G, 100 mA/cm2 illumination, a high open‐circuit voltage (Voc) of 0.9 V was recorded for P3‐based device due to its low HOMO level, and moderate fill factor was obtained with the best value of 58.6% for P4‐based device, which may mainly be the result of the high hole mobility of the polymers (up to 1.82 × 10−3 cm2/V s). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Synthesis of novel copolymers obtained from acceptor/donor radical copolymerization of phosphonated allyl monomers and maleic anhydride
Authors: Negrell‐Guirao C. , David G. , Boutevin B. , Chougrani K.
Published: June 2011

A series of four phosphonated‐bearing allyl monomers, that is, diethyl‐1‐allylphosphonate (AP), dimethyl‐1‐allyloxymethylphosphonate (AOP), 5‐ethyl‐5‐(allyloxymethyl)‐2‐oxo‐1,3,2‐dioxaphosphorinane (AEDPH), and 2‐benzyl‐5‐ethyl‐5‐(allyloxymethyl)‐2‐oxo‐1,3,2‐dioxaphosphorinane (AEDPBn) were synthesized. These monomers were then copolymerized by free radical polymerization in the presence of maleic anhydride, thus leading to alternated copolymers with phosphonate moieties. It was shown that both monomer conversion and reaction rate were dependent on the phosphonate moieties carried out by the allyl monomer: the bulkier the phosphonate group, the higher the polymerization rate. Thermogravimetric analysis of the copolymers revealed a high content of residue, also varying with the nature of the phosphonate moieties. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Covalent surface functionalization of multiwalled carbon nanotubes through bergman cyclization of enediyne‐containing dendrimers
Authors: Ma Jianguo , Deng Sheng , Cheng Xin , Wei Wei , Hu Aiguo
Published: June 2011

A method for covalent functionalization of multiwalled carbon nanotubes (MWCNTs) was developed using the free radicals generated through Bergman cyclization of enediyne‐containing compounds. Four enediyne‐bearing Frechet type dendrimers were synthesized in good quantities and characterized. Then, the enediyne‐containing molecules were reacted with MWCNTs in N‐methyl‐2‐pyrrolidinone at 206 °C under nitrogen. The structure and morphology of the resulting products were characterized by thermogravimetric analysis, ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and transmission electron microscopy. The dendrimer‐functionalized MWCNTs showed good solubility/dispersibility in common organic solvents and polymer solutions. They were used in the formation of polymer composites through electrospinning with polycaprolactone. The results confirmed the surface functionalization of MWCNTs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Influence of nanoparticle surface chemistry on the thermomechanical and magnetic properties of ferromagnetic nanocomposites
Authors: Cruz‐Montoya Edwin De La , Rinaldi Carlos
Published: June 2011

The effect of nanoparticle surface chemistry on the thermal, mechanical, and magnetic properties of poly(methyl methacrylate) (PMMA) nanocomposites with cobalt ferrite nanofillers was studied by comparing nanofillers coated with oleic acid (OA; which does not covalently bond to the PMMA matrix) and 3‐methacryloxypropyltrimethoxysilane (MPS, which covalently bonds to the PMMA matrix). Thermogravimetric analysis revealed an increase in the thermal degradation temperature of the nanocomposites compared with the neat polymer. The effect of cobalt ferrite nanofiller on the glass transition temperature (Tg) of the nanocomposite was evaluated by differential scanning calorimetry. The Tg value of the material increased when the particles were introduced. Dynamic mechanical analysis indicated an increase in the storage modulus of the nanocomposite because of the presence of nanofiller and a shift in the peak of loss tangent toward higher temperature. Magnetic measurements indicated that both nanocomposites had a small hysteresis loop at 300 K and no hysteresis at 400 K. However, estimates of the nanofiller's rotational relaxation times and measurements of the zero field cooled temperature‐dependent magnetization indicate that the observed lack of hysteresis at 400 K is likely because of particle rotation in the polymer matrix. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Water absorption in polyaniline emeraldine base
Authors: Canales Manel , Aradilla David , Alemán Carlos
Published: June 2011

Atomistic classical molecular dynamics simulations have been used to investigate the water absorption behavior of polyaniline emeraldine base. Results derived from simulations, which were performed considering polymeric systems with different concentrations of water (3%, 10%, 15%, 20%, 50%, and 100% w/w), have been compared with experimental evidences obtained for both powder and films. Calculation of the Hildebrand solubility parameters explains not only the insolubility of polyaniline in water but also the requirements, in terms of intermolecular interactions, needed by solvents to be compatibles with this polymer. The maximum content of absorbed water predicted for hygroscopic polyaniline is 15% w/w. The effects of the absorbed water in both the organization and conformation of the polymer chains have been examined at the microscopic level by analyzing the microstructures derived from simulations, while the role of the moisture in the morphology of powder and film samples has been investigated using atomic force microscopy. The overall of the results provides a complete and understandable view of the polyaniline·water interactions, and explains the influence of the water molecules in the structural properties of the polymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1322–1331, 2011
Block copolymer strategies for solar cell technology
Authors: Topham Paul D. , Parnell Andrew J. , Hiorns Roger C.
Published: June 2011

A simple overview of the methods used and the expected benefits of block copolymers in organic photovoltaic devices is given in this review. The description of the photovoltaic process makes it clear how the detailed self‐assembly properties of block copolymers can be exploited. Organic photovoltaic technology, an inexpensive, clean and renewable energy source, is an extremely promising option for replacing fossil fuels. It is expected to deliver printable devices processed on flexible substrates using high‐volume techniques. Such devices, however, currently lack the long‐term stability and efficiency to allow organic photovoltaics to surpass current technologies. Block copolymers are envisaged to help overcome these obstacles because of their long term structural stability and their solid‐state morphology being of the appropriate dimensions to efficiently perform charge collection and transfer to electrodes. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Phase transformation and enhancement of toughness in polyvinylidene fluoride by onium salts
Authors: Vijayakumar R. P. , Khakhar Devang V. , Misra Ashok
Published: June 2011

We study the effect of onium salts (benzyl triphenyl phosphonium chloride, BTPC; tetrabutyl ammonium perchlorate, TAP) on the crystallization of polyvinylidene fluoride (PVDF) from a melt. The β phase of PVDF crystals is polar and has excellent piezoelectric properties, in contrast to the nonpolar α phase. Processing of PVDF results in the formation of predominantly α‐phase crystals. Different amounts of the onium salts were melt‐mixed into PVDF using a micro‐compounder. PVDF containing about 0.5 wt % of BTPC is found to have predominantly β‐phase crystals in compression molded PVDF films, with an increase in the melting temperature by about 7 °C. A significant increase in the toughness of PVDF is obtained by the addition of BTPC. Polarizing microscopy indicates that the onium salts act as nucleating agents and result in significant reduction in spherulite size. Similar results were observed for samples prepared with TAP. The results of the study indicate a facile method for producing β‐phase PVDF films. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1339–1344, 2011
Microwave ECR Plasma Assisted MOCVD of Y2O3 Thin Films Using Y(tod)3 Precursor and Their Characterization
Authors: Barve Shruti , Deo Mukul , Kar Rajib , Sreenivasan Nimisha , Kishore Ramaswamy , Biswas Arup , Bhanage Bhalchandra , Rao Mohan , Gantayet Lalit Mohan , Patil Dinkar
Published: June 2011

Yttrium oxide (Y2O3) thin films were deposited by microwave electron cyclotron resonance (ECR) plasma assisted metal organic chemical vapour deposition (MOCVD) process using indigenously developed metal organic precursors Yttrium 2,7,7‐trimethyl‐3,5‐octanedionates, commonly known as Y(tod)3 which were synthesized by an ultrasound method. A series of thin films were deposited by varying the oxygen flow rate from 1–9 sccm, keeping all other parameters constant. The deposited coatings were characterized by X‐ray photoelectron spectroscopy, glancing angle X‐ray diffraction and infrared spectroscopy. Thickness and roughness for the films were measured by stylus profilometry. Optical properties of the coatings were studied by the spectroscopic ellipsometry. Hardness and elastic modulus of the films were measured by nanoindentation technique. Being that microwave ECR CVD process is operating‐pressure‐sensitive, optimum oxygen activity is very essential for a fixed flow rate of precursor, in order to get a single phase cubic yttrium oxide in the films. To the best of our knowledge, this is the first effort that describes the use of Y(tod)3 precursor for deposition of Y2O3 films using plasma assisted CVD process.

magnified image
What could hemoptysis hide in an otherwise healthy child?
Authors: Nenna Raffaella , Papoff Paola , Moretti Corrado , Cangiano Giulia , Ferro Valentina , Salvadei Serena , Soda Giuseppe , Mennini Maurizio , Midulla Fabio
Published: June 2011

We describe a previously healthy 12‐year‐old boy who attended our Department after a sudden episode of hemoptysis and recurrent consolidation. CT‐scan revealed a mediastinal tumor. The biopsy specimens taken from the mass showed a mature teratoma. Hemoptysis is an unusual presenting symptom in an otherwise healthy child with a well capsulated, unruptured mature mediastinal teratoma. In this report, hemoptysis prompted us to undertake the diagnostic work‐up that eventually disclosed the tumor. Pediatr. Pulmonol. 2011; 46:1146–1148. © 2011 Wiley Periodicals, Inc.
Validation of a school‐based written questionnaire for asthma case identification in Argentina
Authors: Busi Luciano E. , Sly Peter D. , Restuccia Sebastián , Llancamán Lidia
Published: June 2011

Recognition of asthma in community‐based surveys can be problematic. We sought to develop and validate questionnaires that could identify elementary school‐aged children likely to have asthma or who had poorly‐controlled asthma. Questionnaires for parents (PQ) and students (SQ) to complete were developed using guidance on question wording from a focus group consisting of children with asthma and their parents. The gold standard for this study was a pulmonologist determination of asthma and this was used to calculate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) for each question and for combinations of questions. Questionnaires were distributed to 830 children attending elementary schools in Trelew, Argentina and 96% were returned. Test–retest reliability was determined in 221 randomly selected parents and children and very good levels of agreement were seen for individual questions. Asthma was diagnosed in 92 students. Overall, the PQ was able to detect asthma better than the SQ. Optimal diagnostic ability came by combining questions from the PQ and SQ. Not surprisingly, these questionnaires had a better NPV than PPV and can be used to determine which children require further evaluation. Pediatr Pulmonol. Pediatr Pulmonol. 2012; 47:1–7. © 2010 Wiley Periodicals, Inc.
High‐throughput measurement, correlation analysis, and machine‐learning predictions for pH and thermal stabilities of Pfizer‐generated antibodies
Authors: King Amy C. , Woods Matthew , Liu Wei , Lu Zhijian , Gill Davinder , Krebs Mark R. H.
Published: June 2011

Generating stable antibodies is an important goal in the development of antibody‐based drugs. Often, thermal stability is assumed predictive of overall stability. To test this, we used different internally created antibodies and first studied changes in antibody structure as a function of pH, using the dye ANS. Comparison of the pH50 values, the midpoint of the transition from the high‐pH to the low‐pH conformation, allowed us for the first time to rank antibodies based on their pH stability. Next, thermal stability was probed by heating the protein in the presence of the dye Sypro Orange. A new data analysis method allowed extraction of all three antibody unfolding transitions and showed close correspondence to values obtained by differential scanning calorimetry. T1%, the temperature at which 1% of the protein is unfolded, was also determined. Importantly, no correlations could be found between thermal stability and pH50, suggesting that to accurately quantify antibody stability, different measures of protein stability are necessary. The experimental data were further analyzed using a machine‐learning approach with a trained model that allowed the prediction of biophysical stability using primary sequence alone. The pH stability predictions proved most successful and were accurate to within pH ±0.2.
Serum prostate specific antigen changes in cynomolgus monkeys (Macaca fascicularis) on a high sugar high fat diet
Authors: Mubiru James N. , Garcia‐Forey Magdalena , Cavazos Nicole , Hemmat Peggah , Dick Edward J. , Owston Michael A. , Bauer Cassondra A. , Shade Robert E. , Rogers Jeffrey
Published: June 2011

BACKGROUND

An inverse relationship between serum prostate specific antigen (PSA) levels and body mass index (BMI) has been reported in men but not in any animal model.

METHODS

Serum PSA in a colony of cynomolgus monkeys was assayed and correlated to body weight, prostate weight, and age. In addition, 15 animals were selected and fed a high sugar high fat (HSHF) diet for 49 weeks to increase their BMI and correlate it to PSA

RESULTS

Serum PSA levels were positively correlated to prostate weight (r = 0.515, P = 0.025) and age (r = 0.548, P = 0.00072) but was not significantly correlated to body weight (r = −0.032, P = 0.419). For the animals on the HSHF diet, body weight, lean mass, fat mass, and BMI were significantly higher at 49 weeks than at baseline (P < 0.01). PSA was not significantly correlated to body weight and insulin at both baseline and 49 weeks. PSA was negatively correlated to BMI and insulin resistance (HOMA‐IR) at 49 weeks but not at baseline. In addition, we observed hepatic steatosis and increases in serum liver enzymes.

CONCLUSIONS

Increases in BMI in cynomolgus monkeys as a result of consuming a HSHF diet resulted in PSA changes similar to those in humans with increased BMI. Cynomolgus monkeys are a useful model for investigating the relationship between obesity, diabetes, and PSA changes resulting from prostate gland pathology. Prostate 72:469–475, 2012. © 2011 Wiley Periodicals, Inc.
How T cell receptors interact with peptide‐MHCs: A multiple steered molecular dynamics study
Authors: Cuendet Michel A. , Zoete Vincent , Michielin Olivier
Published: June 2011

The T‐cell receptor (TCR) interaction with antigenic peptides (p) presented by the major histocompatibility complex (MHC) molecule is a key determinant of immune response. In addition, TCR‐pMHC interactions offer examples of features more generally pertaining to protein‐protein recognition: subtle specificity and cross‐reactivity. Despite their importance, molecular details determining the TCR‐pMHC binding remain unsolved. However, molecular simulation provides the opportunity to investigate some of these aspects. In this study, we perform extensive equilibrium and steered molecular dynamics simulations to study the unbinding of three TCR‐pMHC complexes. As a function of the dissociation reaction coordinate, we are able to obtain converged H‐bond counts and energy decompositions at different levels of detail, ranging from the full proteins, to separate residues and water molecules, down to single atoms at the interface. Many observed features do not support a previously proposed two‐step model for TCR recognition. Our results also provide keys to interpret experimental point‐mutation results. We highlight the role of water both in terms of interface resolvation and of water molecules trapped in the bound complex. Importantly, we illustrate how two TCRs with similar reactivity and structures can have essentially different binding strategies. Proteins 2011; © 2011 Wiley‐Liss, Inc.
Predicting large‐scale conformational changes in proteins using energy‐weighted normal modes
Authors: Palmer David S. , Jensen Frank
Published: June 2011

We report the development of a method to improve the sampling of protein conformational space in molecular simulations. It is shown that a principal component analysis of energy‐weighted normal modes in Cartesian coordinates can be used to extract vectors suitable for describing the dynamics of protein substructures. The method can operate with either atomistic or user‐defined coarse‐grained models of protein structure. An implicit reverse coarse‐graining allows the dynamics of all‐atoms to be recovered when a coarse‐grained model is used. For an external test set of four proteins, it is shown that the new method is more successful than normal mode analysis in describing the large‐scale conformational changes observed on ligand binding. The method has potential applications in protein–ligand and protein–protein docking and in biasing molecular dynamics simulations. Proteins 2011; © 2011 Wiley‐Liss, Inc.
What to do when nothing has happened?
Authors: Freeman Raymond “Randy”
Published: June 2011

Often, during a layer of protection analysis (LOPA) or a quantitative risk analysis (QRA) study, historical information indicates no occurrences of a particular undesired event in the plant or system. The simple reply that the frequency or rate is zero because the event has never happened is sometimes heard by the analyst during review meetings. The analyst must then decide on an appropriate measure of the frequency of the undesired event. This article presents methods based on statistical tools for developing a measure of the frequency or failure rate of an event when the historical information includes no occurrences of the event. The article compares the various available statistical tools. Guidance is presented on methods to incorporate historical information of no failures into a LOPA or QRA study. Examples on the application of the recommended methods to deal with the problem are presented. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011
Two safety reviews before formal PHAs
Authors: Wincek John C.
Published: June 2011

Many companies do not formally begin to address process safety for new processes until a detailed design is available for study—this can lead to hazards being overlooked until the formal PHA is performed. At that stage it may be difficult to make fundamental process changes. Even when companies do conduct process safety reviews during the earlier phases of a project, they often lack formalized and documented methodologies. This article describes two safety reviews that should be conducted earlier in the design process: (a) conceptual stage hazard review and (b) preliminary hazard analysis. These reviews will identify and document important safety features such as (a) inherent safety concepts, (b) major accident hazards, and (c) safeguards. These efforts lighten the workload on the formal PHA team, because the major hazards have already been identified and protected against. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2011
Bt maize and integrated pest management ‐ a European perspective
Authors: Meissle Michael , Romeis Jörg , Bigler Franz
Published: June 2011

The European corn borer (Ostrinia nubilalis), the Mediterranean corn borer (Sesamia nonagrioides) and the western corn rootworm (Diabrotica virgifera virgifera) are the main arthropod pests in European maize production. Practised pest control includes chemical control, biological control and cultural control such as ploughing and crop rotation. A pest control option that is available since 1996 is maize varieties that are genetically engineered (GE) to produce insecticidal compounds. GE maize varieties available today express one or several genes from Bacillus thuringiensis (Bt) that target corn borers or corn rootworms. Incentives to growing Bt maize are simplified farm operations, high pest control efficiency, improved grain quality and ecological benefits. Limitations include the risk of resistance evolution in target pest populations, risk of secondary pest outbreaks and increased administration to comply with licence agreements. Growers willing to plant Bt maize in the European Union (EU) often face the problem that authorisation is denied. Only one Bt maize transformation event (MON810) is currently authorised for commercial cultivation, and some national authorities have banned cultivation. Spain is the only EU member state where Bt maize adoption levels are currently delivering farm income gains near full potential levels. In an integrated pest management (IPM) context, Bt maize can be regarded as a preventive (host plant resistance) or a responsive pest control measure. In any case, Bt maize is a highly specific tool that efficiently controls the main pests and allows combination with other preventive or responsive measures to solve other agricultural problems including those with secondary pests. Copyright © 2011 Society of Chemical Industry
The susceptibility of small fruits and cherries to the spotted‐wing drosophila, Drosophila suzukii
Authors: Lee Jana C , Bruck Denny J , Curry Hannah , Edwards David , Haviland David R , Van Steenwyk Robert A , Yorgey Brian M
Published: June 2011

BACKGROUND: The spotted‐wing drosophila, Drosophila suzukii Matsumura, is native to Asia and was first detected in the North American mainland and Europe in 2008–2010. Drosophila suzukii is a serious economic pest to stone and small fruits because the female lays eggs within ripening fruit on a plant before harvest, which can lead to crop loss. The aim of this study was to evaluate the susceptibility of blackberries, blueberries, cherries, grapes, raspberries and strawberries to D. suzukii among various ripeness stages and cultivars.

RESULTS: In 26 no‐choice and choice replicated laboratory cage tests on ripeness stages, fruits were generally susceptible to D. suzukii once fruits started to color. Few D. suzukii developed on green fruit, wine grapes or overripe blueberries. In seven cultivar tests, D. suzukii preferences ranged from no differences to fourfold differences for specific cultivars of blackberries, blueberries, raspberries and wine grapes. As brix levels increased, more eggs were laid or more D. suzukii developed on blackberries, blueberries, cherries, raspberries and strawberries. In a choice test of various fruit types, strawberries, raspberries, blackberries, cherries and blueberries were more susceptible to D. suzukii than green table grapes ('Thompson').

CONCLUSION: The results suggest that fruits may become susceptible to D. suzukii as they start to turn color, and that specific varieties of grapes and overripe blueberries have low susceptibility to D. suzukii. Copyright © 2011 Society of Chemical Industry