bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plac1 (placenta‐specific 1) is essential for normal placental and embryonic development
Authors: Jackman Suzanne M. , Kong Xiaoyuan , Fant Michael E. 
Published: June 2012

AbstractPlac1 is a recently identified, X‐linked gene whose expression is restricted primarily to cells of the trophoblast lineage. It localizes to a chromosomal locus previously implicated in placental growth. We therefore sought to determine if Plac1 is necessary for placental and embryonic development by examining a mutant mouse model. Plac1 ablation resulted in placentomegaly and mild intrauterine growth retardation (IUGR). At E16.5, knockout (KO) and heterozygous (Het) placentae of the Plac1‐null allele inherited from the mother (Xm−X) weighed approximately 100% more than wildtype (WT) placentae, whereas the corresponding embryos weighed 7–12% less. Histologically, Plac1 mutants exhibited an expanded spongiotrophoblast layer that invaded the labyrinth. By contrast, Het placentae that inherited the null allele from the father (XXp−) exhibited normal growth and were histologically indistinguishable from WT placentae, consistent with paternal imprinting of Plac1. When examined across gestation, WT and Xm−X placental weights peaked at E16.5 and decreased slightly thereafter. KO placentae (Xm−Xp− and Xm−Y), however, continued to increase in weight after E16.5, consistent with a functional role for the paternal Plac1 allele. Subsequent analysis confirmed that the paternal allele partially escapes complete X‐inactivation and thus contributes to placental growth regulation. Additionally, although male Plac1 KO mice can survive, they exhibit decreased viability as a consequence of events occurring late in gestation or shortly after birth. Thus, Plac1 is a paternally imprinted, X‐linked gene essential for normal placental and embryonic development.Mol. Reprod. Dev. 79: 564‐572, 2012. © 2012 Wiley Periodicals, Inc.
A load balancing strategy for parallel computation of sparse permanents
Authors: Wang Lei , Liang Heng , Bai Fengshan , Huo Yan 
Published: June 2012

SUMMARYThe research in parallel machine scheduling in combinatorial optimization suggests that the desirable parallel efficiency could be achieved when the jobs are sorted in the non‐increasing order of processing times. In this paper, we find that the time spending for computing the permanent of a sparse matrix by hybrid algorithm is strongly correlated to its permanent value. A strategy is introduced to improve a parallel algorithm for sparse permanent. Methods for approximating permanents, which have been studied extensively, are used to approximate the permanent values of submatrices to decide the processing order of jobs. This gives an improved load balancing method. Numerical results show that the parallel efficiency is improved remarkably for the permanents of fullerene graphs, which are of great interests in nanoscience. Copyright © 2012 John Wiley & Sons, Ltd.
A high‐order ADI finite difference scheme for a 3D reaction‐diffusion equation with neumann boundary condition
Authors: Liao Wenyuan 
Published: June 2012

AbstractIn this article, we extend the fourth‐order compact boundary scheme in Liao et al. (Numer Methods Partial Differential Equations 18 (2002), 340–354) to a 3D problem and then combine it with the fourth‐order compact alternating direction implicit (ADI) method in Gu et al. (J Comput Appl Math 155 (2003), 1–17) to solve the 3D reaction‐diffusion equation with Neumann boundary condition. First, the reaction‐diffusion equation is solved with a compact fourth‐order finite difference method based on the Padé approximation, which is then combined with the ADI method and a fourth‐order compact scheme to approximate the Neumann boundary condition, to obtain fourth order accuracy in space. The accuracy in the temporal dimension is improved to fourth order by applying the Richardson extrapolation technique, although the unconditional stability of the numerical method is proved, and several numerical examples are presented to demonstrate the accuracy and efficiency of the proposed new algorithm. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013
Nonstandard finite difference schemes for Michaelis–Menten type reaction‐diffusion equations
Authors: Chapwanya Michael , Lubuma Jean M.‐S. , Mickens Ronald E. 
Published: June 2012

AbstractWe compare and investigate the performance of the exact scheme of the Michaelis–Menten (M–M) ordinary differential equation with several new nonstandard finite difference (NSFD) schemes that we construct using Mickens' rules. Furthermore, the exact scheme of the M–M equation is used to design several dynamically consistent NSFD schemes for related reaction‐diffusion equations, advection‐reaction equations, and advection‐reaction‐diffusion equations. Numerical simulations that support the theory and demonstrate computationally the power of NSFD schemes are presented. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013
A numerical solution for advection‐diffusion equation using dual reciprocity method
Authors: Shiva Afshin , Adibi Hojatollah 
Published: June 2012

AbstractThis article describes a numerical method based on the boundary integral equation and dual reciprocity method(DRM) for solving the one‐dimensional advection‐diffusion equations. The concept of DRM is used to convert the domain integral to the boundary that leads to an integration free method. The time derivative is approximated by the time‐stepping method. Numerical results are presented for some problems to demonstrate the usefulness and accuracy of the new approach. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013
Study on the photoinduced electron‐transfer activity of poly(p‐phenylene benzobisoxazole)/carboxylic multiwalled carbon nanotubes composites prepared by in situ polymerization
Authors: Xie Zhong , Liu Xiaoyun , Zhuang Qixin , Chen Yi , Mao Xiaoyang , Han Zhewen 
Published: June 2012

AbstractThis article focused on the synthesis of poly(p‐phenylene benzobisoxazole)/carboxylic multiwalled carbon nanotubes (PBO/MWNT‐COOH) composites through in situ polymerization. The effect of MWNT‐COOH on thermal stability and photophysical properties was investigated thoroughly. Especially an in‐depth study was carried out on the detailed process of energy transfer. Ultraviolet‐visible‐near infrared and fluorescence spectroscopy of composites revealed that MWNT interacted with PBO through strong covalent bonds, which was a significant photoinduced charge‐transfer interaction between the two components. Therefore, compared with PBO, both the thermal stability and PL quantum efficiency of PBO/MWNT‐COOH composites were improved. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Views of British community pharmacists on direct patient reporting of adverse drug reactions (ADRs)
Authors: Krska Janet 
Published: June 2012

ABSTRACTPurposeTo survey British community pharmacists’ views and practices concerning direct patient reporting of ADRs.MethodsCross‐sectional postal survey of community pharmacists in BritainResultsOf 1096 questionnaires distributed, 297 usable responses were obtained, (27.1%). Respondents’ estimates of the frequency of patients reporting a suspected ADR to them had a median of 1.0 per month. Almost a fifth of respondents (19.6%) do not specifically ask patients about ADRs, and 38.7% do not encourage patients to report.Only 18.5% displayed a poster promoting the YC Scheme in their pharmacy, but 57.9% claimed to have patient YCs available. A quarter (24.9%) of respondents considered that ADR reporting should be restricted to health professionals and 14.4% considered that patients were not at all capable of identifying ADRs.ConclusionsThe low response rate and overall results suggest that British community pharmacists may lack interest in and do not promote direct patient reporting. Increased awareness of the benefits and mechanisms of patient reporting may be required to ensure that pharmacists can provide the necessary support to facilitate patient reporting. Copyright © 2012 John Wiley & Sons, Ltd.
Synthesis and characterization of polyurethanes containing glucose for selective determination of epinephrine in the presence of a high concentration of ascorbic acid
Authors: Paşahan Aziz , Köytepe Süleyman , Cengiz Mahmut Alper , Seçkin Turgay 
Published: June 2012

AbstractPolyurethane (PU) films were prepared from glucose, ethylene glycol and diphenylmethane diisocyanate and used to construct a novel polymer electrode for the detection of epinephrine (EP) in the presence of a high concentration of ascorbic acid (AA). The NCO:OH molar ratio was kept constant at 1 and the saccharide content was varied. The PUs were characterized using Fourier transform infrared spectroscopy, differential scanning calorimetry and differential thermal and thermogravimetric analyses, with intrinsic viscosity and adhesive properties also being evaluated. The PUs exhibited high glass transition temperature, good thermal stability and good adhesive properties. The incorporation of saccharides into the PU structure resulted in a higher crosslinking density and a higher content of hard segments. Medium‐ to high‐molecular‐weight polymers were obtained, with inherent viscosities near or higher than 0.98–2.14 dL g−1. The solubility of the PUs was much better than that of aromatic PUs. The modified polymer electrodes were then used to determine EP in the presence of a high concentration of AA using differential pulse voltammetry. From the amperometric results for the PU electrode, it is concluded that a PU film containing 5 wt% glucose can be used as a membrane for EP detection in the presence of a large concentration of AA, because of its strong adherence to the electrode surface, easy preparation, chemical stability, selectivity and very high statistical confidence (R = 0.9994). © 2012 Society of Chemical Industry
Nanocomposite materials based on isosorbide methacrylate/Cloisite 20A
Authors: Mansoori Yaghoub , Hemmati Salar , Eghbali Parvin , Zamanloo Mohammad Reza , Imanzadeh Golamhassan 
Published: June 2012

AbstractThis paper reports experiments on grafting of a new polymerizable monomer onto organophilic montmorillonite. The monomer, 5‐methacryloyloxy‐1,4:36‐D‐anhydrosorbitol (MAS), was synthesized by reacting methacryloyl chloride and isosorbide in the presence of Et3N as base. Then, Cloisite 20A was reacted with vinyltrichlorosilane to replace the edge hydroxyl groups of the clay with a vinyl moiety. Because the reaction liberates HCl, it was performed in the presence of sodium hydrogen carbonate to prevent the exchange of quaternary alkylammonium cations with H+ ions. Only the silanol groups on the edge of the clay react with vinyltrichlorosilane. After the reaction, the product maintained the same basal spacing as the precursor. The radical polymerization of the product with MAS as a vinyl monomer led to chemical grafting of the polymer onto the montmorillonite surface. The homopolymer formed during polymerization was separated from the grafted organoclay by Soxhlet extraction. Chemical grafting of the polymer onto Cloisite 20A was confirmed using infrared spectroscopy. The prepared nanocomposite materials and the grafted nanoparticles were studied using X‐ray diffraction and scanning and transmission electron microscopy. Exfoliated nanocomposite was obtained for 1 wt% clay loadings. The nanocomposites were studied using thermogravimetric and dynamic mechanical analyses. Improved thermal properties were observed for nanocomposites with 1–5 wt% clay content. © 2012 Society of Chemical Industry
Molecular dynamics study of gramicidin a in lipid bilayer: Structure and lateral pressure profile
Authors: Saito Hiroaki , Iwayama Masashi , Takagi Hiroyuki , Nishimura Megumi , Miyakawa Takeshi , Kawaguchi Kazutomo , Takasu Masako , Mizukami Taku , Nagao Hidemi 
Published: June 2012

AbstractThe structure and lateral pressure profile of the 1,2‐dimyristoyl‐sn‐glycero‐3‐phosphatidylcholine (DMPC) and 1,2‐distearoyl‐sn‐glycero‐3‐phosphatidylcholine (DSPC) lipid bilayers in the absence and presence of gramicidin A (GA) are studied by molecular dynamics simulation. Due to the hydrophobic mismatch between the GA and DSPC lipid bilayer, the chain conformation became disordered, and the hydrophobic thickness around the GA largely decreased to fit the length of hydrophobic core region of the GA. The polar headgroup of lipid was found to orient toward the membrane normal as the lipid approaches the GA. The surface tension around the polar headgroup region in the DMPC/GA membrane decreased due to the decrease of electrostatic interactions between the headgroups. The larger lateral pressure in the hydrophobic region of the DSPC/GA membrane causes the reduction of pore radius around the GA channel entrance, suggesting the decrease of ion accessibility to the GA channel entrance. © 2012 Wiley Periodicals, Inc.
Characterisation of protein nanotubes by ToF‐SIMS imaging
Authors: Poleunis Claude , Dupont‐Gillain Christine , Demoustier‐Champagne Sophie , Delcorte Arnaud , Kalaskar Deepak 
Published: June 2012

A growing number of nano‐objects such as nanotubes, capsules or beads are being developed for various biological and medical applications. In particular, the use of polymer templates for the synthesis of nanomaterials, using layer‐by‐layer assembly, has become a method of choice due to its simplicity and versatility in shapes and dimensions. However, chemical characterisation of these nano‐objects still remains challenging. Here, we report the use of ToF‐SIMS, especially in the imaging mode, for the characterisation of collagen‐based nano‐ and microtubes deposited on surfaces, with a view to applications in biomaterials science.The classical univariate or multivariate Principal Component Analysis (PCA) spectral data treatments do not display any significant differences between the nanotubes with different layer sequences (protein‐polymer or polymer‐protein). However, the layer sequences are clearly differentiated by the ToF‐SIMS images acquired at high lateral resolution (0.3 µm), combined with high mass resolution (m/Δm > 5000 @ 29 m/z), because of the complexity of the protein spectral pattern. These results highlight the importance of imaging for chemical analysis of nanoparticles‐coated samples. This study has particular relevance for nanoscale imaging of biointerfaces. Copyright © 2012 John Wiley & Sons, Ltd.
Resistance Random Access Memory Based on a Thin Film of CdS Nanocrystals Prepared via Colloidal Synthesis
Authors: Ju Yong Chan , Kim Seungwook , Seong Tae‐Geun , Nahm Sahn , Chung Haegeun , Hong Kwon , Kim Woong 
Published: June 2012

AbstractWe demonstrate that resistance random access memory (RRAM) can be fabricated based on CdS‐nanocrystal thin films. A simple drop‐drying of the CdS‐nanocrystal solution leads to the formation of uniform thin films with controlled thickness. RRAMs with a Ag/Al2O3/CdS/Pt structure show bipolar switching behavior, with average values of the set voltage (VSet) and reset voltage (VReset) of 0.15 V and –0.19 V, respectively. The RRAM characteristics are critically influenced by the thickness of the Al2O3 barrier layer, which prevents significant migration of Ag into the CdS layer as revealed by Auger electron spectroscopy (AES). Interestingly, RRAM without an Al2O3 layer (i.e., Ag/CdS/Pt structure) also shows bipolar switching behavior, but the polarity is opposite to that of RRAM with the Al2O3 layer (i.e., Ag/Al2O3/CdS/Pt structure). The operation of both kinds of devices can be explained by the conventional conductive bridging mechanism. Additionally, we fabricated RRAM devices on Kapton film for potential applications in flexible electronics, and the performance of this RRAM device was comparable to that of RRAMs fabricated on hard silicon substrates. Our results show a new possibility of using chalcogenide nanocrystals for RRAM applications.
“I never thought of it as freezing”: How students answer questions on large‐scale science tests and what they know about science
Authors: Noble Tracy , Suarez Catherine , Rosebery Ann , O'Connor Mary Catherine , Warren Beth , Hudicourt‐Barnes Josiane 
Published: June 2012

AbstractEducation policy in the U.S. in the last two decades has emphasized large‐scale assessment of students, with growing consequences for schools, teachers, and students. Given the high stakes of such tests, it is important to understand the relationships between students' answers to test items and their knowledge and skills in the tested content area. Due to persistent test score gaps, students from historically non‐dominant communities, and their teachers and schools, are differentially affected by the consequences of large‐scale testing. As a result, it is particularly important to understand how students from historically non‐dominant communities interact with test items on large‐scale tests. We report on a study in which we interviewed 36 students about their responses to six multiple‐choice science test items from the Massachusetts state science assessment for fifth grade. The 36 students included 12 students from low‐income households, 12 English Language Learners, and 12 middle‐class native English speakers. We found that for five of the six selected test items, students' descriptions of the science content knowledge they used to answer the test items frequently did not match the content knowledge targeted by the items. In addition, students from low‐income households and English Language Learners were more likely than middle‐class native English speakers to answer incorrectly despite demonstrating knowledge of the targeted science content for the items. We argue that such evidence challenges the expectation that students' answers to individual test items reflect their knowledge of the targeted science content, and that evidence of this kind should be included in investigations of the validity of large‐scale tests. © 2012 Wiley Periodicals, Inc. J Res Sci Teach 49: 778–803, 2012
The internationalization of African firms 1995–2011: Review and implications
Authors: Ibeh Kevin , Wilson Juliette , Chizema Amon 
Published: June 2012

AbstractThis article draws on aggregate evidence from 54 relevant studies to improve understanding of internationalization behavior of African firms. Its major findings include an upward trend in internationalization activities among African firms; a significant level of informal exporting (which indicates a potential for further growth in firm‐level internationalization within Africa); and the importance of managerial and organizational resource factors and formal and informal networks in improving the internationalization behavior of the study firms. Based on the review evidence, the article calls on African governments and supranational institutions to prioritize the provision of more enabling environments (with lower transaction/operational costs) in Africa. It also tasks policy makers to incorporate well‐targeted capacity‐building measures (managerial and organizational) and international networks activation mechanisms as part of their core strategies for improving the participation of African firms in global trade. The article ends with an invitation to the world's corporate giants and investors to demonstrate greater resolve toward confronting Africa's developmental challenge, by unleashing their investment resources on the many and varied opportunities offered by the continent. © 2012 Wiley Periodicals, Inc.
Political and institutional impediments to foreign direct investment inflows to sub‐Saharan Africa
Authors: Cleeve Emmanuel 
Published: June 2012

AbstractThis article analyzes the role of institutional factors and political stability in the inflow of foreign direct investment (FDI) to sub‐Saharan Africa (SSA). It uses cross‐sectional time series data on 40 SSA countries, and an econometric model of 12 institutional (including political risk) variables, after controlling for both traditional and policy variables. Given the role of foreign direct investment in the development process, one of the most important challenges facing Africa is how to attract an improved share of the increasing flow of world FDI. Africa's image as a high‐risk investment region has to be dispelled, as the flow of FDI is highly sensitive to economic and political risks. Fiscal incentives, the most popular instrument for attracting FDI in Africa, have failed to deliver the expected increase in FDI inflows. We believe that what is needed is not only political and macroeconomic stability but also institutional credibility. The objective of this article, therefore, is to investigate the impact of institutional factors and political risk on the inflow of FDI to SSA. The results reveal that institutional factors are important to attract FDI into SSA. © 2012 Wiley Periodicals, Inc.
Internationalization of established small manufacturers in a developing economy: A case study of Kenyan SMEs
Authors: Jekanyika Matanda Margaret 
Published: June 2012

AbstractThis article discusses the findings of a study of the internationalisation of established small manufacturing firms in Kenya. The findings suggest established SMEs pursued an incremental approach to internationalization, as most established operations in the domestic market before moving to foreign markets. The interviews revealed the internationalization process was mostly driven by firm based‐factors such as managerial orientation, maintaining business reputing, enhancing market share and revenue, technological advancement, and flexibility of operations. Environmental‐based factors such as similarity in foreign and domestic markets, instability, and saturation of domestic markets played a lesser role. The article concludes with a discussion of research and managerial implications. © 2012 Wiley Periodicals, Inc.
Corporate social responsibility (CSR) practices of foreign and local companies in Ghana
Authors: Kuada John , Hinson Robert E. 
Published: June 2012

AbstractThis article reports a comparative study of the key motives underlying corporate social responsibility (CSR) practices of foreign and local firms operating in Ghana and the societal as well as business outcomes of these practices. The results show that while the CSR decisions of foreign firms are mainly guided by legal prescriptions, those of their local counterparts are guided mostly by discretionary and social considerations. The socially oriented CSR practices of the local firms are consistent with cultural expectations in Ghana that those with extra resources should support the less privileged members of the society. But the difference in the degree of importance that the two groups of firms attach to discretionary motives for their CSR practices is not statistically significant. The article also discusses the policy, strategy, and research implications of the findings. © 2012 Wiley Periodicals, Inc.
Deregulation, competition, and performance measurement of an African airport: The case of Kotoka international airport of Ghana
Authors: Akwei Cynthia , Tsamenyi Mathew , Sa'id Hadiza 
Published: June 2012

AbstractThis article reports on the results of a case study that explores the performance measurement practice in one of the growing airports in Africa‐the Kotoka International Airport (KIA) of Ghana. The article also assesses the performance of the airport from the perspectives of three groups of stakeholders ‐the airlines, passengers, and the community. KIA, like other airports around the world, is facing unprecedented challenges in terms of traffic growth, deregulation and increased commercial focus, the globalization of airline and airport activity, and the need to be environmentally aware. To manage these challenges, there is the need for the airport authorities to be proactive and innovative in their approach to performance measurement. This requires focusing not only on financial performance but also on other measures such as quality of service and environmental performance. Though the airport measures financial and quality of service performance, it does not pay much attention to environmental performance, and this was reflected in the ratings provided by the community. © 2012 Wiley Periodicals, Inc.