bluuebunny/crossref_metadata_2025 huggingface dataset:
Loss of equilibrative nucleoside transporter 1 in mice leads to progressive ectopic mineralization of spinal tissues resembling diffuse idiopathic skeletal hyperostosis in humans
Authors: Warraich Sumeeta , Bone Derek BJ , Quinonez Diana , Ii Hisataka , Choi Doo-Sup , Holdsworth David W , Drangova Maria , Dixon S Jeffrey , Séguin Cheryle A , Hammond James R
Published: November 2012

Diffuse idiopathic skeletal hyperostosis (DISH) is a noninflammatory spondyloarthropathy, characterized by ectopic calcification of spinal tissues. Symptoms include spine pain and stiffness, and in severe cases dysphagia and spinal cord compression. The etiology of DISH is unknown and there are no specific treatments. Recent studies have suggested a role for purine metabolism in the regulation of biomineralization. Equilibrative nucleoside transporter 1 (ENT1) transfers hydrophilic nucleosides, such as adenosine, across the plasma membrane. In mice lacking ENT1, we observed the development of calcified lesions resembling DISH. By 12 months of age, ENT1–/– mice exhibited signs of spine stiffness, hind limb dysfunction, and paralysis. Micro–computed tomography (µCT) revealed ectopic mineralization of paraspinal tissues in the cervical-thoracic region at 2 months of age, which extended to the lumbar and caudal regions with advancing age. Energy-dispersive X-ray microanalysis of lesions revealed a high content of calcium and phosphorus with a ratio similar to that of cortical bone. At 12 months of age, histological examination of ENT1–/– mice revealed large, irregular accumulations of eosinophilic material in paraspinal ligaments and entheses, intervertebral discs, and sternocostal articulations. There was no evidence of mineralization in appendicular joints or blood vessels, indicating specificity for the axial skeleton. Plasma adenosine levels were significantly greater in ENT1–/– mice than in wild-type, consistent with loss of ENT1—a primary adenosine uptake pathway. There was a significant reduction in the expression of Enpp1, Ank, and Alpl in intervertebral discs from ENT1–/– mice compared to wild-type mice. Elevated plasma levels of inorganic pyrophosphate in ENT1–/– mice indicated generalized disruption of pyrophosphate homeostasis. This is the first report of a role for ENT1 in regulating the calcification of soft tissues. Moreover, ENT1–/– mice may be a useful model for investigating pathogenesis and evaluating therapeutics for the prevention of mineralization in DISH and related disorders. © 2013 American Society for Bone and Mineral Research.
Serum 25-hydroxyvitamin D and risk of major osteoporotic fractures in older U.S. adults
Authors: Looker Anne C
Published: November 2012

Results from previous prospective studies linking serum 25-hydroxyvitamin D (25OHD) with fracture risk have been inconsistent. The present study examined the relationship between serum 25OHD and risk of incident major osteoporotic fracture (hip, spine, radius, and humerus) in older U.S. adults. The study used a pooled cohort of 4749 men and women ages 65 years and older from the third National Health and Nutrition Examination Survey (NHANES III, 1988–1994) and NHANES 2000–2004. Incident fractures were identified using linked mortality and Medicare records that were obtained for participants from both surveys. Serum 25OHD values were measured by radioimmunoassay in both surveys. Cox proportional hazards models were used to estimate the relative risk (RR) of fracture by serum 25OHD level. There were 525 incident major osteoporotic fractures (287 hip fractures) in the sample. Serum 25OHD was a significant linear predictor of major osteoporotic fracture and significant quadratic predictor of hip fracture in the total sample and among those with less than 10 years of follow-up, but it was not related to risk of either fracture type among those with ≥10 years of follow-up. Major osteoporotic fracture risk was increased by 26% to 27% for each SD decrease in serum 25OHD among those with less than 10 years of follow-up. Serum 25OHD was significantly related to risk of major osteoporotic fractures as a group and to hip fracture alone in this cohort of older U.S. adults from NHANES III and NHANES 2000–2004. However, the predictive utility of serum 25OHD diminished after 10 years. In addition, the relationship appeared to be linear when major osteoporotic fracture risk was considered but quadratic when hip fracture risk was assessed. © 2013 American Society for Bone and Mineral Research.
Gpr177, a novel locus for bone mineral density and osteoporosis, regulates osteogenesis and chondrogenesis in skeletal development
Authors: Maruyama Takamitsu , Jiang Ming , Hsu Wei
Published: November 2012

Human genetic analysis has recently identified Gpr177 as a susceptibility locus for bone mineral density and osteoporosis. Determining the unknown function of this gene is therefore extremely important to furthering our knowledge base of skeletal development and disease. The protein encoded by Gpr177 exhibits an ability to modulate the trafficking of Wnt, similar to the Drosophila Wls/Evi/Srt. Because it plays a critical role in Wnt regulation, Gpr177 might be required for several key steps of skeletogenesis. To overcome the early lethality associated with the inactivation of Gpr177 in mice, conditional gene deletion is used to assess its functionality. Here we report the generation of four different mouse models with Gpr177 deficiency in various skeletogenic cell types. The loss of Gpr177 severely impairs development of the craniofacial and body skeletons, demonstrating its requirement for intramembranous and endochondral ossifications, respectively. Defects in the expansion of skeletal precursors and their differentiation into osteoblasts and chondrocytes suggest that Wnt production and signaling mediated by Gpr177 cannot be substituted. Because the Gpr177 ablation impairs Wnt secretion, we therefore identify the sources of Wnt proteins essential for osteogenesis and chondrogenesis. The intercross of Wnt signaling between distinct cell types is carefully orchestrated and necessary for skeletogenesis. Our findings lead to a proposed mechanism by which Gpr177 controls skeletal development through modulation of autocrine and paracrine Wnt signals in a lineage-specific fashion. © 2013 American Society for Bone and Mineral Research.
Characterization of malignancy of adnexal lesions using ADC entropy: Comparison with mean ADC and qualitative DWI assessment
Authors: Kierans Andrea S. , Bennett Genevieve L. , Mussi Thais C. , Babb James S. , Rusinek Henry , Melamed Jonathan , Rosenkrantz Andrew B.
Published: November 2012

Purpose:

To establish the utility of apparent diffusion coefficient (ADC) entropy in discrimination of benign and malignant adnexal lesions, using histopathology as the reference standard, via comparison of the diagnostic performance of ADC entropy with mean ADC and with visual assessments of adnexal lesions on conventional and diffusion‐weighted sequences.

Materials and Methods:

In all, 37 adult female patients with an ovarian mass that was resected between June 2006 and January 2011 were included. Volume‐of‐interest was drawn to incorporate all lesion voxels on every slice that included the mass on the ADC map, from which whole‐lesion mean ADC and ADC entropy were calculated. Two independent radiologists also rated each lesion as benign or malignant based on visual assessment of all sequences. The Mann–Whitney test and logistic regression for correlated data were used to compare performance of mean ADC, ADC entropy, and the visual assessments.

Results:

No statistically significant difference was observed in mean ADC between benign and malignant adnexal lesions (P = 0.768). ADC entropy was significantly higher in malignant than in benign lesions (P = 0.009). Accuracy was significantly greater for ADC entropy than for mean ADC (0.018). ADC entropy and visual assessment by the less‐experienced reader showed similar accuracy (P ≥ 0.204). The more experienced reader's accuracy was significantly greater than that of all other assessments (P ≤ 0.039).

Conclusion:

ADC entropy showed significantly greater accuracy than the more traditional metric of mean ADC for distinguishing benign and malignant adnexal lesions. Although whole‐lesion ADC entropy provides a straightforward and objective measurement, its potential benefit decreases with greater reader experience. J. Magn. Reson. Imaging 2013;37:164–171. © 2012 Wiley Periodicals, Inc.
Subtraction artifacts and frequency (Mis‐)alignment in J‐difference GABA editing
Authors: Evans C. John , Puts Nicolaas A.J. , Robson Siân E. , Boy Frederic , McGonigle David J. , Sumner Petroc , Singh Krish D. , Edden Richard A.E.
Published: November 2012

Purpose

To compare the repeatability of γ‐aminobutyric acid (GABA) measurements using J‐difference editing, before and after spectral realignment—a technique which has previously been demonstrated to improve the quality of J‐difference GABA spectra.

Materials and Methods

We performed in vivo measurements in three brain regions (occipital, sensorimotor, and dorsolateral prefrontal cortex [DLPFC]), and analyzed these using alternative alignment approaches to evaluate the impact of alignment on repeatability: “Independent alignment” (aligning each subspectrum independently) and “Pairwise alignment” (aligning each on and off subspectrum as a pair) were compared.

Results

Pairwise alignment improved the group mean coefficient of variation in all regions; 0.4% in occipital, 1.1% in sensorimotor, and 1.1% in DLPFC. Independent alignment resulted in subtraction artifacts in the majority of cases, and increased the coefficient of variation in the DLPFC by 9.4%. Simulations demonstrate that the GABA quantification error in datasets with high B0 drift, is 4.5% without alignment, but <1% with optimal alignment.

Conclusion

Pairwise alignment improves the repeatability of GABA spectroscopy data. However, independently aligning all on and off subspectra can lead to artifacts and worse repeatability when compared with nonaligned data. J. Magn. Reson. Imaging 2013;38:970–975. © 2012 Wiley Periodicals, Inc.
Quantification of BOLD fMRI parameters to infer cerebrovascular reactivity of the middle cerebral artery
Authors: Mazzetto‐Betti Kelley C. , Leoni Renata F. , Pontes‐Neto Octavio M. , Sturzbecher Marcio J. , Santos Antonio C. , Leite Joao P. , Silva Afonso C. , de Araujo Draulio B.
Published: November 2012

Purpose

To quantify the amplitude and temporal aspects of the blood oxygenation level‐dependent (BOLD) response to an auditory stimulus during normocapnia and hypercapnia in healthy subjects in order to establish which BOLD parameters are best suited to infer the cerebrovascular reactivity (CVR) in the middle cerebral artery (MCA) territory.

Materials and Methods

Twenty healthy volunteers (mean age: 23.6 ± 3.7 years, 11 women) were subjected to a functional paradigm composed of five epochs of auditory stimulus (3 sec) intercalated by six intervals of rest (21 sec). Two levels of hypercapnia were achieved by a combination of air and CO2 while the end‐tidal CO2 (ETCO2) was continually measured. An autoregressive method was applied to analyze four parameters of the BOLD signal: onset‐time, time‐to‐peak, full‐width‐at‐half‐maximum (FWHM), and amplitude.

Results

BOLD onset time (P < 0.001) and full‐width at half‐maximum (FWHM) (P < 0.05) increased linearly, while BOLD amplitude decreased (P < 0.001) linearly with increasing levels of hypercapnia. Test–retest for reproducibility in five subjects revealed excellent concordance for onset time and amplitude.

Conclusion

The robust linear dependence of BOLD onset time, FWHM, and amplitude to hypercapnia suggest future application of this protocol in clinical studies aimed at evaluating CVR of the MCA territory. J. Magn. Reson. Imaging 2013;38:1203–1209. © 2012 Wiley Periodicals, Inc.
Neuroprotective effects of umbelliferone and esculetin in a mouse model of Parkinson's disease
Authors: Subramaniam Sudhakar R. , Ellis Elizabeth M.
Published: November 2012

The production of reactive oxygen species and mitochondrial dysfunction in the brain are both associated with the progression of several neurodegenerative diseases, including Parkinson's disease. These characteristics are also observed when rodents are exposed to the neurotoxin 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP), a compound that causes nigrostriatal dopaminergic neurotoxicity and that has been used previously for assessing the effectiveness of neuroprotective agents. In this study, the neuroprotective effects of two coumarins, umbelliferone and esculetin, against MPTP‐induced neurotoxicity were examined in C57BL/6J mice. The results show that dietary administration of umbelliferone and esculetin significantly attenuated MPTP‐induced neurotoxicity in the substantia nigra pars compacta but not striatum, as measured by tyrosine hydroxylase staining. Both coumarins also prevented an MPTP‐induced increase in nitrosative stress as measured by 3‐nitrotyrosine immunoreactivity and also maintained glutathione levels in MPTP‐exposed mice as well as in cell lines exposed to the metabolite 1‐methyl‐4‐phenylpyridinium. Umbelliferone and esculetin also prevented MPTP‐dependent caspase 3 activation, an indicator of apoptosis, but did not inhibit monoamine oxidase activity. This is the first time that the neuroprotective capabilities of these coumarins have been demonstrated, and the results indicate that umbelliferone and esculetin can protect against MPTP‐induced neurotoxicity in the mouse. These compounds can cross the blood–brain barrier, so their effectiveness indicates that they have the potential to protect in neurodegenerative disease such as Parkinson's disease. © 2012 Wiley Periodicals, Inc.
The Compartamos microfinance IPO: Mission conflicts in hybrid institutions with diverse shareholding
Authors: Ashta Arvind , Hudon Marek
Published: November 2012

Compartamos is an exemplary case of private equity‐backed governance in microfinance.
Micro‐equity and social entrepreneurship from a venture capital perspective
Authors: Estapé‐Dubreuil Glòria , Ashta Arvind , Hédou Jean‐Pierre
Published: November 2012

The French micro‐angels are social investors interested in helping micro‐enterprises survive.
Book review: A comparison of two books of microfinance pioneers
Authors: Ashta Arvind , Milana Carlo
Published: November 2012

Vikram Akula, A Fistful of Rice: My Unexpected Quest to End Poverty Through Profitability, Harvard Business School Publishing, Boston, MA, 2011, ISBN 978‐1‐4221‐3117‐6, Hardcover US$26.95, 191 pages.

Muhamad Yunus, Banker to the Poor: Micro‐Lending and the Battle Against World Poverty, PublicAffairs, New York, 2007, ISBN‐13 978‐1‐58648/ISBN‐10 1‐58648‐198‐3, Paperback US$15.00, 288 pages.
Killian‐Jamieson diverticulum
Authors: Undavia Satyen , Anand Sumeet M. , Jacobson Adam S.
Published: November 2012

Killian‐Jamieson diverticulum (KJD) is rare hypopharyngeal defect. As in other forms of esophageal diverticuli (i.e., Zenker's), recent literature has described minimally invasive endoscopic approaches to its management.1, 2 We present a case of a 62‐year‐old female with symptoms consistent with an esophageal diverticulum. A barium swallow study was consistent with a KJD. The patient was brought to the operating room and endoscopically examined to confirm the presence of this entity. A open transcervical approach was performed to remove the diverticulum without complication. During our dissection, the recurrent laryngeal nerve (RLN) was noted to be adherent to the base of the diverticulum and needed to be freed prior to performing the diverticulectomy. We provide a review of recent literature and medical illustrations to highlight the importance of the open transcervical approach in the management of KJD to avoid inadvertent transection of the RLN.
Facial nerve repair
Authors: Knox Christopher J. , Hohman Marc H. , Kleiss Ingrid J. , Weinberg Julie S. , Heaton James T. , Hadlock Tessa A.
Published: November 2012

Objectives/Hypothesis

Repair of the transected facial nerve has traditionally been accomplished with microsurgical neurorrhaphy; however, fibrin adhesive coaptation (FAC) of peripheral nerves has become increasingly popular over the past decade. We compared functional recovery following suture neurorrhaphy to FAC in a rodent facial nerve model.

Study Design

Prospective, randomized animal study.

Methods

Sixteen rats underwent transection and repair of the facial nerve proximal to the pes anserinus. Eight animals underwent epineurial suture (ES) neurorrhaphy, and eight underwent repair with fibrin adhesive (FA). Surgical times were documented for all procedures. Whisking function was analyzed on a weekly basis for both groups across 15 weeks of recovery.

Results

Rats experienced whisking recovery consistent in time course and degree with prior studies of rodent facial nerve transection and repair. There were no significant differences in whisking amplitude, velocity, or acceleration between suture and FA groups. However, the neurorrhaphy time with FA was 70% shorter than for ES (P < 0.05).

Conclusion

Although we found no difference in whisking recovery between suture and FA repair of the main trunk of the rat facial nerve, the significantly shorter operative time for FA repair makes this technique an attractive option. The relative advantages of both techniques are discussed.

Level of Evidence

N/A
Two‐Grid method for nonlinear parabolic equations by expanded mixed finite element methods
Authors: Chen Yanping , Chen Luoping , Zhang Xiaochun
Published: November 2012

In this article, we develop a two‐grid algorithm for nonlinear reaction diffusion equation (with nonlinear compressibility coefficient) discretized by expanded mixed finite element method. The key point is to use two‐grid scheme to linearize the nonlinear term in the equations. The main procedure of the algorithm is solving a small‐scaled nonlinear equations on the coarse grid and dealing with a linearized system on the fine space using the Newton iteration with the coarse grid solution. Error estimation to the expanded mixed finite element solution is analyzed in detail. We also show that two‐grid solution achieves the same accuracy as long as the mesh sizes satisfy H = O(h1/2). Two numerical experiments are given to verify the effectiveness of the algorithm. © 2012 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013
A cross‐cultural perspective on aging and memory: Comparisons between Bangladesh and Sweden
Authors: Sternäng Ola , Kabir Zarina N. , Hamadani Jena D. , Wahlin Åke
Published: November 2012

Most studies on cognitive aging have been conducted in high‐income countries (mainly on Western populations). The main aim of this study was to compare the relative importance of predictors of episodic and semantic memory performance in older people (≥60 years) from Bangladesh (n = 400) and Sweden (n = 1,098). Hierarchical regression models were used in order to study the importance of some commonly used predictors in the two countries. A main finding was that variations in age did not have much impact on episodic and semantic memory performance in Bangladesh. Instead, sex was a strong predictor for semantic memory performance. In Sweden this pattern was reversed. In the Western world, chronological age is believed to be strongly associated with memory performance in cross‐sectional studies, particularly in people greater than 60 years of age. This study indicates that the difference between the two countries (in relative importance of the predictors included in this study) is mainly due to the fact that years of education is connected to age in the Western world but to sex in Bangladesh. It remains to be examined whether earlier selective survival is also responsible for the relative absence of cognitive age differences in Bangladesh.
Neural bases for basic processes in heuristic problem solving: Take solving Sudoku puzzles as an example
Authors: Qin Yulin , Xiang Jie , Wang Rifeng , Zhou Haiyan , Li Kuncheng , Zhong Ning
Published: November 2012

Newell and Simon postulated that the basic steps in human problem‐solving involve iteratively applying operators to transform the state of the problem to eventually achieve a goal. To check the neural basis of this framework, the present study focused on the basic processes in human heuristic problem‐solving that the participants identified the current problem state and then recalled and applied the corresponding heuristic rules to change the problem state. A new paradigm, solving simplified Sudoku puzzles, was developed for an event‐related functional magnetic resonance imaging (fMRI) study in problem solving. Regions of interest (ROIs), including the left prefrontal cortex, the bilateral posterior parietal cortex, the anterior cingulated cortex, the bilateral caudate nuclei, the bilateral fusiform, as well as the bilateral frontal eye fields, were found to be involved in the task. To obtain convergent evidence, in addition to traditional statistical analysis, we used the multivariate voxel classification method to check the accuracy of the predictions for the condition of the task from the blood oxygen level dependent (BOLD) response of the ROIs, using a new classifier developed in this study for fMRI data. To reveal the roles that the ROIs play in problem solving, we developed an ACT‐R computational model of the information‐processing processes in human problem solving, and tried to predict the BOLD response of the ROIs from the task. Advances in human problem‐solving research after Newell and Simon are then briefly discussed.
Preparation and phase behavior of blends of polysulfone‐based polymers with phosphorous‐containing smectic‐A liquid crystals
Authors: Vlad‐Bubulac Tachita , Serbezeanu Diana , Hamciuc Corneliu , Petreus Oana , Carja Ionela‐Daniela , Lisa Gabriela
Published: November 2012

Preparation and experimental studies on the phase transitions and morphology of novel polymer‐dispersed liquid crystal (PDLC) mixtures of polysulfone UDEL‐3000 (PSU) or its derivatives (chloromethylated polysulfone or polysulfone containing lateral phosphaphenanthrene substituent) and a phosphorus‐containing liquid crystalline polymer (LCC) that exhibit isotropic/nematic/smectic‐A mesophase transition were performed. The mesomorphic properties of PDLC have been investigated by differential scanning calorimetry and polarizing optical microscopy. Mesophases structures were also investigated by X‐ray diffraction measurements, the diffraction pattern being in close dependence on the polysulfone structure and PDLC composition. The effect of the phosphorus content on the thermal properties was evaluated by thermogravimetric analysis. The results reveal that the composites were stable up to 337°C in air showing initial decomposition temperatures in the range of 337–368°C and a 10% weight loss in the range of 357–397°C. The presence of P in the structure of LCC leads to higher char yields at 700°C, for PDLCs composites, increasing with the content of phosphorus‐containing polymer. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Methods for quantifying the stable sintering region in laser sintered polyamide‐12
Authors: Vasquez M. , Haworth B. , Hopkinson N.
Published: November 2012

Manufacturing complex parts by the laser sintering process requires a minimum amount of energy input for consolidation of polymer particles to occur; however too much energy can result in a decline in mechanical properties. This decrease is thought to be the result of polymer chain degradation. A stable sintering region (SSR) has been proposed to describe the optimum temperature range for successful laser sintering. This article will aim to quantify the SSR for polyamide‐12 by using thermogravimetric analysis (TGA) to provide a framework for identifying key laser sintering processing parameters. Weight loss with respect to temperature is the main measurement output of the TGA procedure. However, the precise temperature and thermal history of a material is difficult to quantify during the laser sintering process; instead an energy input approach has been developed. A degradation energy was calculated from the TGA data and was used in conjunction with a laser sintering formula called energy melt ratio to prescribe build parameters for laser sintered parts. The mechanical properties of these parts illustrated the effect of degradation at various levels of energy input. Implications for this work include optimizing the material selection process for polymer laser sintering materials beyond polyamide‐12. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Recycling of thermoset polyurethane foams
Authors: Quadrini Fabrizio , Bellisario Denise , Santo Loredana
Published: November 2012

A new way for recycling polyurethane (PU) foams is shown by scrap pulverization and subsequent compression molding of resulting particles. The compression molding stage is also called “direct molding” to highlight the absence of any linking agent or virgin material. Large disks, 190 mm in diameter, were molded by recycling foam scraps from motorcycle seats. Aluminum alloy molds and a hot parallel press plate press were used: the molding temperature was fixed to 180°C, the molding pressure to 4.2 MPa, and the molding time to 15 min, whereas the weight of the particles to mold was changed so as to obtain disks with different thickness. The final density of molded product was close to 1 g/cm3, resulting in a compacting factor of 14 in comparison with the initial PU foam. Indentation tests and tensile tests showed that final products exhibit good mechanical performances. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Morphology, crystallization, thermal, and mechanical properties of poly(vinylidene fluoride) films filled with different concentrations of polyhedral oligomeric silsesquioxane
Authors: Liu Yizhi , Sun Yi , Zeng Fanlin , Chen Yunjun , Li Qingkun , Yu Bowen , Liu Wenjing
Published: November 2012

Nanocomposites consisting of a poly(vinylidene fluoride) (PVDF) matrix and 0–8 wt% fluoropropyl polyhedral oligomeric silsesquioxane (FP‐POSS) were obtained through the solvent evaporation method. Morphology, crystallization, as well as thermal and mechanical properties were investigated. FP‐POSS, acting as a nucleating agent, exhibited robust miscibility with PVDF, enhancing the crystallinity of PVDF. A high relative fraction of the β phase was observed in the composites. The thermal degradation of PVDF was not significantly affected by FP‐POSS under a nitrogen atmosphere. Low addition of FP‐POSS, acting as nanofiller, led to remarkable improvement in mechanical properties, including hardness. The maximum was achieved at 3 wt%. High amounts led to inferior mechanical properties. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
The influence of isosorbide on thermal properties of poly(L‐lactide) synthesized by different methods
Authors: Ristić Ivan S. , Radusin Tanja , Pilić Branka , Cakić Suzana , Budinski‐Simendić Jaroslava
Published: November 2012

In this article, we analyzed the influence of isosorbide content on glass transition temperature and crystallinity of poly(L‐lactide). Different synthesis methods were applied to determine optimal procedure for polymerization of L‐lactide in the presence of isosorbide. Two procedures were performed with tin(II) 2‐ethylhexanoate as the catalyst: first, using the vacuum sealed vessel, and second, using microwave reactor bulk polymerizations. The solution polymerization (with trifluoromethanesulfonic acid as catalyst) was possible at the temperature of 40°C. Obtained polyesters had number average molecular weights ranging from 20,000 to 65,000 g mol–1, according to the gel permeation chromatography measurements. The polymer structure was characterized by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. Thermal properties of the obtained polymers were analyzed using thermogravimetry (TG) and differential scanning calorimetry (DSC). According to DSC measurements, the addition of isosorbide in the polyesters influenced the increase in both glass transition temperature and degree of crystallization for all samples. The results obtained by thermogravimetric analysis confirmed the strong influence of polymerization mechanism on synthesized poly(L‐lactides) thermal properties. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
Covalently cross‐linked and hydrophobically modified alginic acid hydrogels and their application as drug carriers
Authors: Wu Min , Ni Caihua , Yao Bolong , Zhu Changping , Huang Bo , Zhang Liping
Published: November 2012

Covalently crosslinked and hydrophobically modified alginate hydrogels were prepared through esterification of alginic acid (ALG‐H) with 1,10‐decanediol that functioned as a crosslinking agent and hydrophobic component. The preparation was accomplished with one step and was carried out in N,N‐dimethylformamide solution at a reduced pressure for removing the water produced. The characterization results confirmed the esterification of the products. The modified alginate hydrogels could be used as drug delivery vehicles for controlled release. The drug release study revealed that compared with a calcium alginate hydrogel the modified hydrogels possessed improved loading rate and encapsulation efficiency for the hydrophobic drug(ibuprofen), and a remarkable sustained release behavior was observed. The release kinetics was close to zero order, a desirable drug release pattern. The modified alginate hydrogels were nontoxic and were potentially applicable as a promising biomaterial. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers
The Effect of Test Translation on the Performance of Second Grade English Learners on the KeyMath‐3
Authors: Alt Mary , Arizmendi Genesis D. , Beal Carole R. , Hurtado J. Sayleen
Published: November 2012

This study was conducted to determine whether Spanish‐enhanced administration of a standardized math assessment would result in improved scores for English Learners who used Spanish as a heritage language. Twenty‐one typically developing second‐graders (English Learners) were administered the traditional KeyMath‐3. If the child made an error on an item, a Spanish version of the item was presented. Difference scores were calculated to determine whether the Spanish‐enhanced version resulted in improved scores. Data were analyzed using paired t‐tests and simple regression. The data results showed that all children significantly benefited from the Spanish‐enhanced administration of items answered incorrectly in English. The amount of benefit was predicted by a child's degree of Spanish dominance. It was concluded that standardized math tests that do not accommodate second‐language learners may be inadvertently testing language skills in addition to math skills. Implications for assessment and interpretations of assessments are discussed.
Linear and star‐shaped POSS hybrid materials containing crystalline isotactic polystyrene chains
Authors: Vielhauer Maximilian , Lutz Pierre J. , Reiter Günter , Mülhaupt Rolf
Published: November 2012

New crystalline nanostructured inorganic–organic hybrid materials containing isotactic polystyrene (iPS) are prepared by means of hydrosilylation coupling of vinyl‐terminated iPS with octakis(dimethylsilyloxy)silsesquioxane (Q8M8H). The number average molar mass of the iPS chains varies between 2000 and 6000 g mol−1. As a function of the iPS/Q8M8H ratio, using excess reagent, the formation of linear or star‐shaped hybrid architectures is achieved. Via fractionation, it is possible to isolate well‐defined linear hybrids containing one iPS chain and seven ethyl groups per silica core (iPS‐Q8M8E7) as well as star‐shaped hybrids containing up to eight iPS side chains (iPS6‐8‐Q8M8). These new iPS/polyhedral oligomeric silsesquioxane hybrid materials crystallize when the number average molar mass of iPS side chain exceeds 5500 g mol−1. The hydrosilylation coupling reaction and the resulting linear iPS‐Q8M8E7 and star‐shaped iPS6‐8‐Q8M8 are characterized by NMR spectroscopy, size exclusion chromatography (gel permeation chromatography), and polarized light microscopy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Formation of a porphyrin/fullerene light‐harvesting system from self‐assembly of porphyrin‐end‐functionalized polycyclohexane and [6,6]‐phenyl‐C61‐butyric acid methyl ester: Effects of microphase separation and π–π interactions
Authors: Natori Itaru , Natori Shizue , Kanasashi Anna , Tsuchiya Kosuke , Ogino Kenji
Published: November 2012

Thin films composed of zinc tetraphenylporphyrin‐end‐functionalized polycyclohexane (ZnTPP‐PCHE) and [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) blends were prepared to investigate their potential as light‐harvesting systems within polymer solar cells (PSCs). Both the microphase separation characteristics and the extent of π–π interactions in these ZnTPP‐PCHE/PCBM blends had significant effects on the optical properties of the films. The extent to which the absorption bands of the films overlapped the terrestrial solar spectrum was increased considerably when the blends formed a co‐continuous structure, even though films of pure ZnTPP‐PCHE or PCBM exhibited only weak absorption over that wavelength region. We conclude that these polymer blend films may be considered as viable candidates for light‐harvesting systems within PSCs. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013
Preparation and Properties of An Insensitive Booster Explosive Based on LLM‐105
Authors: Xu Wenzheng , An Chongwei , Wang Jingyu , Dong Jun , Geng Xiaoheng
Published: November 2012

A new insensitive booster explosive based on 2,6‐diamino‐3,5‐dinitropyrazing‐1‐oxide (LLM‐105) was prepared by a solvent‐slurry process with ethylene propylene diene monomer (EPDM) as binder. SEM (scanning electron microscopy) was employed to characterize the morphology and particle size of LLM‐105 and molding powder. The mechanical sensitivity, thermal sensitivity, shock wave sensitivity, and detonation velocity of the LLM‐105/EPDM booster were also measured and analyzed. The results show that both mechanical sensitivity and thermal sensitivity of LLM‐105/EPDM are much lower than that of conventional boosters, such as PBXN‐5 and A5. Its shock wave sensitivity is also lower than that of PBXN‐5 and PBXN‐7. When the density of charge is 95 % TMD, its theoretical and measured detonation velocities are 7858 m s−1 and 7640 m s−1, respectively. These combined properties suggested that LLM‐105/EPDM can be used as an insensitive booster.
Study on the Compatibility of Tetraethylammonium Decahydrodecaborate (BHN) with some Energetic Components and Inert Materials
Authors: Pang Weiqiang , Fan Xuezhong , Xue Yunna , Xu Huixiang , Zhang Wei , Zhang Xiaohong , Li Yonghong , Li Yang , Shi Xiaobing
Published: November 2012

The compatibility of tetraethylammonium decahydrodecaborate (BHN) with some energetic components and inert materials of solid propellants was studied by DSC method, where glycidyl azide polymer (GAP), cyclotrimethylenetrinitramine (RDX), cyclotetramethylenetetranitroamine (HMX), lead 3‐nitro‐1,2,4‐triazol‐5‐onate (NTO‐Pb), hexanitrohexaazaisowurtzitane (CL‐20), 3,4‐dinitrofurzanfuroxan (DNTF), N‐guanylurea‐dinitramide (GUDN), aluminum powder (Al, particle size=12.18 μm) and magnesium powder (Mg, particle size: 44–74 μm) were used as energetic components and polyoxytetramethylene‐co‐oxyethylene (PET), polyethylene glycol (PEG), addition product of hexamethylene diisocyanate and water (N‐100), hydroxyl terminated polybutadiene (HTPB), cupric adipate (AD‐Cu), cupric 2,4‐dihydroxy‐benzoate (β‐Cu), lead phthalate (ϕ‐Pb), carbon black (C. B.), aluminum oxide (Al2O3), 1,3‐dimethyl‐1,3‐diphenyl urea (C2), di‐2‐ethylhexyl sebacate (DOS) and potassium perchlorate (KP), were used as inert materials. It was concluded that the binary systems of BHN with NTO‐Pb, CL‐20, aluminum powder, magnesium powder, PET, PEG, N‐100, AD‐Cu, β‐Cu, ϕ‐Pb, C. B., Al2O3, C2, DOS, and KP are compatible, and systems of BHN with GAP and HMX are slightly sensitive, and with RDX, DNTF, and GUDN are incompatible. The impact and friction sensitivity data of BHN and BHN in combination with the energetic materials under present study were obtained, and there was no consequential affiliation between sensitivity and compatibility.
Isocyanate‐Free and Dual Curing of Smokeless Composite Rocket Propellants
Authors: Landsem Eva , Jensen Tomas L. , Kristensen Tor E. , Hansen Finn K. , Benneche Tore , Unneberg Erik
Published: November 2012

Traditional composite rocket propellants are cured by treatment of hydroxyl‐terminated prepolymers with polyfunctional aliphatic isocyanates. For development of smokeless composite propellants containing nitramines and/or ammonium dinitramide (ADN), energetic binder systems using glycidyl azide polymer (GAP) are of particular interest. Polyfunctional alkynes are potential isocyanate‐free curing agents for GAP through thermal azide‐alkyne cycloaddition and subsequent formation of triazole crosslinkages. Propargyl succinate or closely related aliphatic derivatives have previously been reported for such isocyanate‐free curing of GAP. Herein, we present the synthesis and use of a new aromatic alkyne curing agent, the crystalline solid bisphenol A bis(propargyl ether) (BABE), as isocyanate‐free curing agent in smokeless propellants based on GAP, using either octogen (HMX) and/or prilled ADN as energetic filler materials. Thermal and mechanical properties, impact and friction sensitivity and ballistic characteristics were evaluated for these alkyne cured propellants. Improved mechanical properties could be obtained by combining isocyanate and alkyne curing agents (dual curing), a combination that imparted better mechanical properties in the cured propellants than either curing system did individually. The addition of a neutral polymeric bonding agent (NPBA) for improvement of binder‐filler interactions was also investigated using tensile testing and dynamic mechanical analysis (DMA). It was verified that the presence of isocyanates is essential for the NPBA to improve the mechanical properties of the propellants, further strengthening the attractiveness of dual cure systems.
Thermal Analysis of Magnesium/Perfluoropolyether Pyrolants
Authors: Rider Keith B. , Little Brian K. , Emery Samuel B. , Lindsay C. Michael
Published: November 2012

Exothermic reactions between metals and fluorinated polymers are found in a variety of energetic materials, including reactive binder systems and the Magnesium‐Teflon‐Viton incendiary composition. This paper describes the reactions between a high molecular weight perfluoropolyether, Fomblin Y 140/13, and magnesium in a variety of morphologies including μm‐scale powders and nano‐scale layered films. Using Temperature Programmed Desorption and Temperature Programmed Reaction we have found that the magnesium‐perfluoropolyether interaction is characterized by: (1) competition between Fomblin decomposition and desorption, and (2) magnesium passivation by the formation of magnesium fluoride. Differential Scanning Calorimetry measurements establish a lower‐bound estimate of the specific reaction energy of 9.2 kJ g−1. High molecular weight Fomblin (6500 amu) undergoes a competitive reaction/desorption process with desorption occurring at 550 K and decomposition at 610 K. Decomposition becomes more favorable relative to desorption for higher heating rates and thicker films. Perfluoropolyethers produce several characteristic ions in the 70 eV election ionization mass spectra, with the CF3+ ion being the most abundant ion observed during both the molecular desorption and decomposition. Larger fragment ions with masses of 235 and 285 amu are observed in relatively high concentrations during desorption and low concentrations during decomposition. The reaction between magnesium and Fomblin begins at 400 K, producing CF3+, CO+, and C2F5+ in the electron ionization mass spectrum. We propose that these reactions form a passivating layer of magnesium fluoride that protects the remaining metal as it approaches the magnesium melting point. Most of the reaction takes place at 800 K and above when the magnesium fluoride film ruptures.
Identity‐based optimistic fair exchange in the standard model
Authors: Zhang Lei , Wu Qianhong , Qin Bo
Published: November 2012

A fair exchange protocol allows two entities to exchange digital signatures over open networks in a fair way, so that either each entity obtains the other's signature or neither entity does. Fair exchange protocol plays an important role in electronic commerce in the case of exchanging digital contracts. In this paper, we propose a fair exchange protocol based on identity‐based verifiably encrypted signatures. Our protocol involves an offline trusted third party which is only required when one entity attempts to cheat or crashes. The underlining identity‐based verifiably encrypted signature scheme is proven secure under the computational Diffie–Hellman assumption and is the first identity‐based verifiably encrypted signature scheme provably secure against existential unforgeable under adaptive chosen message and identity attacks in the standard model. Copyright © 2012 John Wiley & Sons, Ltd.
Evolution styles: using architectural knowledge as an evolution driver
Authors: Cuesta Carlos E. , Navarro Elena , Perry Dewayne E. , Roda Cristina
Published: November 2012

Software evolution is an increasingly challenging and compelling concern for every developed software system because of the changes in the requirements, the technology, etc. When software evolution is carried out, software architecture emerges as one of the cornerstones that should be considered from two different points of view: as an artifact for the evolution, as it helps the architect plan and restructure the system, and as an artifact of the evolution, because it has to be modified as well. This paper focuses on the second point of view—that is, on the evolution of the software architecture, but taking into account architectural knowledge as a key driver of the process. Given that architecture rationale and design intent are critical in evolving software systems, it is imperative that they be captured in some useful form to aid that evolution process. We present a new approach for evolution styles that extends them by considering in their description the architectural knowledge as a valuable asset of the evolution process. Copyright © 2012 John Wiley & Sons, Ltd.
Minocycline promotes axonal regeneration through suppression of RGMa in rat MCAO/reperfusion model
Authors: Tao Tao , Xu Guanghui , Si Chen Cindy , Feng Jinzhou , Kong Yuhan , Qin Xinyue
Published: November 2012

Minocycline has been recently implicated in protection against focal cerebral ischemia reperfusion (I/R), but the protective effects on neurobehavioral abnormalities remains contradictory. In the present study, we investigate whether minocycline improves axonal regeneration and neurological function recovery by inhibiting the expression of the repulsive guidance molecular A (RGMa) after focal cerebral ischemia reperfusion. Male Sprague‐Dawley (SD) rats were subjected to occlusion of the right middle cerebral artery (MCAO) for 2 h and 3 mg kg−1 minocycline was injected intravenously immediately after reperfusion twice a day for 14 days. The staircase test and modified neurological severity score (mNSS) were performed to evaluate functional outcome and blood‐brain barrier (BBB) permeability was assessed by Evan's blue dye extravasation (EB) at the expected time point. The expression of RGMa in ischemic cortex was measured by immunohistochemical staining and Western blot 2 weeks after MCAO. Neurofilament protein 200 (NF‐200) immunohistochemical staining was used to assess axonal damage. Treatment with minocycline at a dose of 3 mg kg−1 via the caudal vein significantly reduced the extravasation of EB, elevated mNSS and improved forelimb motor function as assessed by the staircase test when compared to the I/R group (P < 0.05). Moreover, axonal regrowth was enhanced in the minocycline treatment group when compared to the I/R group (P < 0.05). In addition, minocycline significantly reduced the expression of RGMa protein 2 weeks after MCAO as assessed by both immunostaining and Western blot. Our studies suggest that early minocycline treatment promotes neurological functional recovery and axonal regeneration in rats after MCAO, which might be mediated by down‐regulating RGMa expression. Synapse, 2013. © 2012 Wiley Periodicals, Inc.
Birth defects associated with perturbations in preimplantation, gastrulation, and axis extension: from conjoined twinning to caudal dysgenesis
Authors: Ferrer‐Vaquer Anna , Hadjantonakis Anna‐Katerina
Published: November 2012

Congenital malformations represent approximately 3 in 100 live births within the human population. Understanding their pathogenesis and ultimately formulating effective treatments are underpinned by knowledge of the events and factors that regulate normal embryonic development. Studies in model organisms, primarily in the mouse, the most prominent genetically tractable mammalian model, have equipped us with a rudimentary understanding of mammalian development from early lineage commitment to morphogenetic processes. In this way, information provided by studies in the mouse can, in some cases, be used to draw parallels with other mammals, including human. Here, we provide an overview of our current understanding of the general sequence of developmental events from early cell cleavages to gastrulation and axis extension occurring in human embryos. We will also review some of the rare birth defects occurring at these stages, in particular those resulting in conjoined twinning or caudal dysgenesis. WIREs Dev Biol 2012, 2:427–442. doi: 10.1002/wdev.97

This article is categorized under:

Establishment of Spatial and Temporal Patterns > Cell Sorting and Boundary Formation

Establishment of Spatial and Temporal Patterns > Regulation of Size, Proportion, and Timing

Signaling Pathways > Cell Fate Signaling

Birth Defects > Associated with Preimplantation and Gastrulation
Systems analysis of biological networks in skeletal muscle function
Authors: Smith Lucas R. , Meyer Gretchen , Lieber Richard L.
Published: November 2012

Skeletal muscle function depends on the efficient coordination among subcellular systems. These systems are composed of proteins encoded by a subset of genes, all of which are tightly regulated. In the cases where regulation is altered because of disease or injury, dysfunction occurs. To enable objective analysis of muscle gene expression profiles, we have defined nine biological networks whose coordination is critical to muscle function. We begin by describing the expression of proteins necessary for optimal neuromuscular junction function that results in the muscle cell action potential. That action potential is transmitted to proteins involved in excitation–contraction coupling enabling Ca2+ release. Ca2+ then activates contractile proteins supporting actin and myosin cross‐bridge cycling. Force generated by cross‐bridges is transmitted via cytoskeletal proteins through the sarcolemma and out to critical proteins that support the muscle extracellular matrix. Muscle contraction is fueled through many proteins that regulate energy metabolism. Inflammation is a common response to injury that can result in alteration of many pathways within muscle. Muscle also has multiple pathways that regulate size through atrophy or hypertrophy. Finally, the isoforms associated with fast muscle fibers and their corresponding isoforms in slow muscle fibers are delineated. These nine networks represent important biological systems that affect skeletal muscle function. Combining high‐throughput systems analysis with advanced networking software will allow researchers to use these networks to objectively study skeletal muscle systems. WIREs Syst Biol Med 2013, 5:55–71. doi: 10.1002/wsbm.1197

This article is categorized under:

Models of Systems Properties and Processes > Mechanistic Models

Physiology > Mammalian Physiology in Health and Disease

Laboratory Methods and Technologies > RNA Methods