bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical Coherence Tomography Reveals New Insights into the Accommodation Mechanism
Authors: Farouk Mahmoud Mohamed , Naito Takeshi , Shinomiya Kayo , Eguchi Hiroshi , Sayed Khulood Mohammed , Nagasawa Toshihiko , Katome Takashi , Mitamura Yoshinori
Published: July 2015

Purpose. To evaluate the movement of the anterior and posterior lens poles during naturally stimulated accommodation in children using anterior segment optical coherence tomography (OCT).Methods. This is a prospective, observational, noncomparative case series including 18 eyes of nine children. Analysis of the anterior segment in the accommodated and unaccommodated state (with cycloplegia) was done using anterior segment OCT. The main outcome measures were the position of the anterior and posterior lens poles (in relation to the cornea) and lens thickness (LT).Results. A Statistically significant forward movement of the anterior lens pole and backward movement of the posterior lens pole with an increase in LT were found during accommodation (P<0.001). There was no significant difference between the degree of movement of the anterior lens pole and the posterior lens pole during accommodation (P=0.944).Conclusions. Anterior segment OCT provides a rapid noncontact method for studying accommodation in children. The backward movement of the posterior lens pole during accommodation nearly equals the forward movement of its anterior pole. These data minimize the theoretical hydraulic effect of the vitreous during accommodation, adding more support to the capsular theory of Helmholtz.
A Modified Eyring Equation for Modeling Yield and Flow Stresses of Metals at Strain Rates Ranging from 10−5to 5 × 104 s−1
Authors: Othman Ramzi
Published: July 2015

In several industrial applications, metallic structures are facing impact loads. Therefore, there is an important need for developing constitutive equations which take into account the strain rate sensitivity of their mechanical properties. The Johnson-Cook equation was widely used to model the strain rate sensitivity of metals. However, it implies that the yield and flow stresses are linearly increasing in terms of the logarithm of strain rate. This is only true up to a threshold strain rate. In this work, a three-constant constitutive equation, assuming an apparent activation volume which decreases as the strain rate increases, is applied here for some metals. It is shown that this equation fits well the experimental yield and flow stresses for a very wide range of strain rates, including quasi-static, high, and very high strain rates (from 10−5to 5 × 104 s−1). This is the first time that a constitutive equation is showed to be able to fit the yield stress over a so large strain rate range while using only three material constants.
Lattice Boltzmann Simulation of Multiple Bubbles Motion under Gravity
Authors: Nie Deming , Lin Jianzhong , Qiu Limin , Zhang Xiaobin
Published: July 2015

The motion of multiple bubbles under gravity in two dimensions is numerically studied through the lattice Boltzmann method for the Eotvos number ranging from 1 to 12. Two kinds of initial arrangement are taken into account: vertical and horizontal arrangement. In both cases the effects of Eotvos number on the bubble coalescence and rising velocity are investigated. For the vertical arrangement, it has been found that the coalescence pattern is similar. The first coalescence always takes place between the two uppermost bubbles. And the last coalescence always takes place between the coalesced bubble and the bottommost bubble. For four bubbles in a horizontal arrangement, the outermost bubbles travel into the wake of the middle bubbles in all cases, which allows the bubbles to coalesce. The coalescence pattern is more complex for the case of eight bubbles, which strongly depends on the Eotvos number.
Solitary Fibrous Tumour of the Parotid Gland: A Case Report and Review of the Literature
Authors: Kwok Matthew M. , Subramaniyan Muthukumar , Chan Sor Way
Published: July 2015

Introduction. Solitary fibrous tumours (SFT) of the parotid gland are a very rare group of spindle-cell tumours with only 28 cases reported in the literature. This review aims to report an additional case of parotid SFT and provide a review of all reported cases of this rare condition.Case Presentation. A 26-year-old male presented a 3 cm well-demarcated, slowly enlarging mass which was completely excised, revealing histological and immunohistochemical features of SFT.Discussion. Reviews of all reported cases suggest that histology and immunohistochemistry are paramount in the diagnosis of SFT. These features, along with clinical presentation and management of this rare condition, will be discussed.
Robust Adaptive Beamforming against Signal Steering Vector Mismatch and Jammer Motion
Authors: Mao Xiaojun , Li Wenxing , Li Yingsong , Sun Yaxiu , Zhai Zhuqun
Published: July 2015

Since adaptive beamformer suffers from output performance degradation in the presence of interference nonstationarity and signal steering vector mismatch, a novel robust null broadening adaptive beamforming is proposed. The proposed method is realized by the combination of projection transform and diagonal loading techniques. First, a new projection matrix with null broadening ability is constructed and then projects the array received data onto the projection matrix. With the diagonal loading technique, a new sample covariance matrix is obtained. The theoretical analysis shows that the projection transform operation can expand the incident direction of the interference and improve orthogonality between the signal-plus-interference and the noise subspaces; thus the proposed beamformer can effectively broaden the jammer null and enhance the null depth. The analytical expressions of the proposed algorithm are also provided, which are efficient and easily solved. Simulation results are presented and demonstrated that the proposed beamformer can provide strong robustness against signal steering vector mismatch and jammer motion.
Synthesis and Properties of Flexible Polyurethane Using Ferric Catalyst for Hypopharyngeal Tissue Engineering
Authors: Shen Zhisen , Wang Jian , Lu Dakai , Li Qun , Zhou Chongchang , Zhu Yabin , Hu Xiao
Published: July 2015

Biodegradable polyurethane is an ideal candidate material to fabricate tissue engineered hypopharynx from its good mechanical properties and biodegradability. We thus synthesized a hydrophilic polyurethane via reactions among polyethylene glycol (PEG), e-caprolactone (e-CL) and hexamethylene diisocyanate (HDI), and thrihydroxymethyl propane (TMP). The product possessed a fast degradability due to its good wettability and good mechanical parameters with the elongations at break (137 ± 10%) and tensile strength (4.73 ± 0.46 MPa), which will make it a good matrix material for soft tissue like hypopharynx. Its biological properties were evaluated viain vitroandin vivotests. The results showed that this hydrophilic polyurethane material can support hypopharyngeal fibroblast growth and owned good degradability and low inflammatory reaction in subcutaneous implantation. It will be proposed as the scaffold for hypopharyngeal tissue engineering research in our future study.
How to Diagnose and Exclude Drug-Induced Liver Injury
Authors: Watkins Paul B.
Published: July 2015

The diagnosis of drug-induced liver injury (DILI) is largely a diagnosis of exclusion because, with the possible exception of protein:drug adducts in paracetamol overdose, there are no laboratory, biopsy or imaging tests that alone are capable of establishing an unequivocal diagnosis of DILI. However, it is increasingly appreciated that drugs that cause DILI typically have characteristic clinical presentations or ‘signatures' that can be very useful in the diagnosis of DILI. Indeed, knowing a drug's DILI signature (or sometimes signatures) and the incidence rate of DILI during treatment with that drug are perhaps the most useful pieces of historical information in arriving at the diagnosis of DILI. Components of the signature include the typical latency from the onset of treatment, whether there are extrahepatic manifestations, whether the injury is hepatocellular, cholestatic or mixed, and sometimes characteristic features on biopsy or serological testing (e.g. liver autoantibodies). A major advance has been the establishment of the LiverTox website (http://livertox.nih.gov/) which provides open access to standardized entries for over 600 different drugs, including the characteristic clinical presentations of DILI when known. LiverTox will also calculate the causality score for individual cases using the RUCAM instrument and case-specific data entered by the site user. However, the problem with standard diagnostic instruments such as the RUCAM is that DILI signatures are not incorporated into the scoring system. The person entering data must therefore subjectively weigh the RUCAM score with the characteristic DILI signature(s) of the drug to arrive at a diagnosis. In the future, it should be possible to construct improved diagnostic instruments that objectively incorporate DILI signatures, data-based estimates of the incidence rates of DILI from each implicated drug, and perhaps genetic variants associated with the risk of DILI.
Therapies: Drugs, Scopes and Transjugular Intrahepatic Portosystemic Shunt - When and How?
Authors: Abraldes Juan G. , Tandon Puneeta
Published: July 2015

Variceal bleeding is the most serious complication of portal hypertension. All cirrhotic patients should be screened endoscopically for varices which are present in about 30% of compensated and 60% of decompensated patients at diagnosis. In patients without varices, endoscopy surveillance should be continued every 2 years. Patients with high-risk varices (moderate or large in size, or with red color signs, or in Child-Pugh C patients) should be treated with a nonselective β-blocker to prevent bleeding (propranolol, nadolol or carvedilol). Endoscopic banding ligation is also effective for the prevention of first bleeding, and it is the first choice in patients with contraindications or intolerance to β-blockers. Acute variceal hemorrhage still has a high mortality rate (around 15%) and requires intensive care management and conservative blood transfusion policy. Treatment is based on the combined use of vasoactive drugs, endoscopic band ligation and prophylactic antibiotics. Failures are best managed by transjugular intrahepatic portosystemic shunt (TIPS). Balloon tamponade or specifically designed covered esophageal stents can be used as a bridge to definitive therapy in unstable patients. Early, preemptive TIPS might be the first choice in patients at high risk of failure (Child-Pugh B with active bleeding or Child-Pugh C up to 13 points). Patients surviving a variceal bleeding are at high risk of rebleeding. A combination of β-blockers and endoscopic band ligation is the most effective therapeutic approach. Preliminary data suggest that the addition of simvastatin increases survival in these patients.
Definition and Diagnosis of Acute Kidney Injury in Cirrhosis
Authors: Wong Florence
Published: July 2015

Background: Acute kidney injury (AKI) is a common complication of advanced cirrhosis. Type 1 hepatorenal syndrome is the best-known and most severe form of AKI, and it has a precise definition and a set of specific diagnostic criteria. More recently, it has become recognized that milder degrees of renal dysfunction also have a negative impact on patient outcome in various patient populations. Key Messages: Several definitions and criteria for staging the severity of AKI have been proposed, including the RIFLE (Risk, Injury, Failure, Loss of Function and End-Stage Renal Disease) group, the Acute Kidney Injury Network (AKIN), and the Kidney Disease: Improving Global Outcome (KDIGO) group. All of them incorporate some changes of serum creatinine and urine output in the definition and staging of AKI. The hepatology community has mostly embraced the AKIN diagnostic and staging criteria and has applied them in the prognostication of patients with advanced cirrhosis. However, the AKIN criteria have not been strictly applied in all studies on cirrhosis. This is partly related to the fact that changes in urine output are difficult to assess in advanced cirrhosis, and partly related to the difficulty in defining the baseline serum creatinine from which the change in serum creatinine is calculated. This has led to some confusion in the interpretation of results of the various studies on AKI in cirrhosis. More recently, some investigators have suggested incorporating the AKIN criteria with setting a lower limit of serum creatinine of 1.5 mg/dl in determining the diagnosis and prognosis of AKI in cirrhosis. Conclusions: This is an ongoing debate as to how best to define AKI in cirrhosis. In the near future there should be prospective clinical trials that will clarify which diagnostic and staging criteria of AKI will best serve the cirrhotic population.
The Clinical Relevance of Minimal Hepatic Encephalopathy - A Critical Look
Authors: Weissenborn Karin
Published: July 2015

Minimal hepatic encephalopathy (mHE) is diagnosed in patients with severe liver disease but no clinical symptoms of encephalopathy if either neuropsychological or neurophysiological tests indicate cerebral dysfunction and other possible causes of brain dysfunction have been excluded. mHE is characterized by deficits in attention, visuospatial orientation, visuoconstructive abilities and motor function. Accordingly, mHE can be expected to interfere with a subject's working ability, especially in those occupations that require handiwork, and driving ability. Indeed, about 60% of blue-collar workers with mHE have been shown to be assessed as unfit for work compared to only 20% of white-collar workers, and about 50% of patients with mHE have been judged unfit to drive a car in several studies. mHE interferes with a patient's quality of life and is associated with an increased risk of developing overt HE as well as increased mortality. Whether mHE is of importance for cognitive function after liver transplantation has still to be clarified.
Challenges and Management of Liver Cirrhosis: Practical Issues in the Therapy of Patients with Cirrhosis due to NAFLD and NASH
Authors: Traussnigg Stefan , Kienbacher Christian , Halilbasic Emina , Rechling Christian , Kazemi-Shirazi Lili , Hofer Harald , Munda Petra , Trauner Michael
Published: July 2015

Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the metabolic syndrome and comprises a liver disease spectrum ranging from steatosis to nonalcoholic steatohepatitis (NASH) with risk of progression to liver cirrhosis and hepatocellular carcinoma (HCC). Associated metabolic conditions and comorbidities such as obesity, diabetes and cardiovascular diseases are common and require concerted management. Adiponutrin (PNPLA3) variants may help to identify NAFLD patients at higher risk for liver disease progression towards advanced fibrosis and HCC. The therapeutic options in NAFLD/NASH include lifestyle modification, pharmacological treatment, bariatric surgery for patients with morbid obesity and treatment of complications of liver cirrhosis and HCC, including liver transplantation. Insulin sensitizers and antioxidative treatment strategies with vitamin E are among the best-established pharmacological approaches, but both drugs have long-term safety issues and there is limited evidence in cirrhotic patients. Treatment of concomitant/underlying metabolic conditions with statins or metformin may also have beneficial effects on portal hypertension, complications of liver cirrhosis and HCC prevention. The bile acid receptor FXR may be a promising novel therapeutic target for the treatment of NAFLD/NASH, fibrosis and portal hypertension, but the prognostic implications of associated changes in low- and high-density lipoprotein cholesterol require further studies. Morbidly obese NASH patients can benefit from bariatric surgery which may reduce liver fibrosis but carries a risk of decompensation in patients with advanced liver cirrhosis. When carefully selected, patients with NASH cirrhosis undergoing liver transplantation have a good outcome. This review summarizes recent progress in the management of patients with liver cirrhosis due to NASH.
Retrospective Assessment of the Utility of Imaging, Fine-Needle Aspiration Biopsy, and Intraoperative Frozen Section in the Management of Parotid Neoplasms: The Weill Cornell Medical College Experience
Authors: Patel Krupa R. , Scognamiglio Theresa , Kutler David I. , Kuhel William I. , Gromis Jonathan , Phillips C. Douglas , Cohen Marc A.
Published: July 2015

Background/Aims: Preoperative identification of malignant parotid lesions remains challenging, and thus, some surgeons use frozen section (FS) to assist them in their decision making. We evaluated the pathologic and cost benefit of FS after fine-needle aspiration (FNA) at our institution. Methods: We assessed medical data for 260 patients undergoing parotidectomy with FS. The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were calculated for radiology, FNA, and FS. Results: The sensitivities, specificities, and accuracies of FNA and FS were 75.0, 96.4, and 93.2%, and 75.0, 100, and 96.8%, respectively. FS detected 0% of FNA false negatives and 80% of false positives. The additional pathology charge for FS alone per correctly identified benign lesion after a positive FNA was USD 1,443. Conclusion: FNA and FS are more reliable in the prognostication of the final pathology than radiology. At our center, FS appears to be of limited clinical use after benign FNAs, but may be more useful after positive, indeterminate, and nondiagnostic FNAs.
Platelet Counts and Patent Ductus Arteriosus in Preterm Infants: A Systematic Review and Meta-Analysis
Authors: Simon Sorina R. , van Zogchel Lieke , Bas-Suárez Maria Pilar , Cavallaro Giacomo , Clyman Ronald I. , Villamor Eduardo
Published: July 2015

Background: Several cohort studies have shown an association between low platelet counts in the first day(s) of life and patent ductus arteriosus (PDA) in preterm infants. However, these results have not been confirmed by other studies. Objective: To perform a meta-analysis of all the studies addressing the relationship between platelet counts in the first day(s) of life and PDA in preterm infants. Methods: PubMed/MEDLINE and EMBASE were searched from their inception until December 2014. Results from 11 cohort studies involving 3,479 preterm infants (gestational age <32 weeks) were pooled using random-effects modeling. Results: Meta-analysis showed a significant positive association between PDA and platelet counts <150 × 109/l [6 studies, risk ratio (RR) = 1.215, 95% CI: 1.027-1.436], between PDA and platelet counts <100 × 109/l (5 studies, RR = 1.255, 95% CI: 1.034-1.525), and between significant PDA (SPDA) and platelet counts <100 × 109/l (5 studies, RR = 1.254, 95% CI: 1.021-1.540). The association between SPDA and platelet counts <150 × 109/l was not statistically significant (6 studies, RR = 1.289, 95% CI: 0.925-1.795). Pooled standard differences in mean platelet counts between infants with and without PDA/SPDA were not statistically different. Conclusion: This meta-analysis reveals a marginal but significant association between low platelet counts in the first day(s) of life and PDA/SPDA in very preterm infants. This association needs to be confirmed in prospective studies.
Age Does Matter: A Pilot Comparison of Placenta-Derived Stromal Cells for in utero Repair of Myelomeningocele Using a Lamb Model
Authors: Brown Erin G. , Keller Benjamin A. , Lankford Lee , Pivetti Christopher D. , Hirose Shinjiro , Farmer Diana L. , Wang Aijun
Published: July 2015

Introduction: Fetal amniotic membranes (FM) have been shown to preserve spinal cord histology in the fetal sheep model of myelomeningocele (MMC). This study compares the effectiveness of placenta-derived mesenchymal stromal cells (PMSCs) from early-gestation versus term-gestation placenta to augment FM repair to improve distal motor function in a sheep model. Methods: Fetal lambs (n = 4) underwent surgical MMC creation followed by repair with FM patch with term-gestation PMSCs (n = 1), FM with early-gestation PMSCs (n = 1), FM only (n = 1), and skin closure only (n = 1). Histopathology and motor assessment was performed. Results: Histopathologic analysis demonstrated increased preservation of spinal cord architecture and large neurons in the lamb repaired with early-gestation cells compared to all others. Lambs repaired with skin closure only, FM alone, and term-gestation PMSCs exhibited extremely limited distal motor function; the lamb repaired with early-gestation PMSCs was capable of normal ambulation. Discussion: This pilot study is the first in vivo comparison of different gestational-age placenta-derived stromal cells for repair in the fetal sheep MMC model. The preservation of large neurons and markedly improved motor function in the lamb repaired with early-gestation cells suggest that early-gestation placental stromal cells may exhibit unique properties that augment in utero MMC repair to improve paralysis.
Prenatally Acquired Multiple Limb Ischemia in a Very Low Birth Weight Monochorionic Twin
Authors: Straňák Zbyněk , Korček Peter , Hympánová Lucie , Kynčl Martin , Krofta Ladislav
Published: July 2015

Limb ischemia is an extremely rare event occuring in monochorionic twin pregnancy complicated by twin-to-twin transfusion syndrome (TTTS) and twin anemia polycythemia sequence (TAPS). The authors describe a case of TTTS and TAPS treated successfully using amnioreduction and laser ablation. However, severe ischemia of both lower extremities in the recipient twin developed after the fetal treatment. This serious complication was diagnosed on MRI in utero and confirmed postnatally. Elective amputation of the affected limbs was performed. The etiology of the disease remains unclear despite profound clinical and histopathological examinations; although the role of thromboembolism in monochorionic pregnancy seems to be most likely, this unique case of multiple limb ischemia with distinct macroscopic findings has not yet been described.
Why Does Aerosol Forcing Control Historical Global-Mean Surface Temperature Change in CMIP5 Models?
Authors: Rotstayn Leon D. , Collier Mark A. , Shindell Drew T. , Boucher Olivier
Published: July 2015

Linear regression is used to examine the relationship between simulated changes in historical global-mean surface temperature (GMST) and global-mean aerosol effective radiative forcing (ERF) in 14 climate models from CMIP5. The models have global-mean aerosol ERF that ranges from −0.35 to −1.60 W m−2 for 2000 relative to 1850. It is shown that aerosol ERF is the dominant factor that determines intermodel variations in simulated GMST change: correlations between aerosol ERF and simulated changes in GMST exceed 0.9 for linear trends in GMST over all periods that begin between 1860 and 1950 and end between 1995 and 2005. Comparison of modeled and observed GMST trends for these time periods gives an inferred global-mean aerosol ERF of −0.92 W m−2.

On average, transient climate sensitivity is roughly 40% larger with respect to historical forcing from aerosols than well-mixed greenhouse gases. This enhanced sensitivity explains the dominant effect of aerosol forcing on simulated changes in GMST: it is estimated that 85% of the intermodel variance of simulated GMST change is explained by variations in aerosol ERF, but without the enhanced sensitivity less than half would be explained. Physically, the enhanced sensitivity is caused by a combination of 1) the larger concentration of aerosol forcing in the midlatitudes of the Northern Hemisphere, where positive feedbacks are stronger and transient warming is faster than in the Southern Hemisphere, and 2) the time evolution of aerosol forcing, which levels out earlier than forcing from well-mixed greenhouse gases.
What motivates entrepreneurial entry under economic inequality? The role of human and financial capital
Authors: Xavier-Oliveira Emanuel , Laplume André O , Pathak Saurav
Published: July 2015

Based on a multilevel analysis of nearly 120,000 observations across 31 countries between 2001 and 2008, we provide novel insights into the moderating effects that economic inequality may have on the distinct roles that human and financial capital play on different types of entrepreneurship. As inequality increases, both forms of capital become weaker deterrents of entry into necessity entrepreneurship, whereas for opportunity entrepreneurship, only financial capital becomes a stronger predictor of entry. We also show that, regardless of inequality levels, both human and financial capital exhibit decreasing marginal returns on the likelihood of entry into necessity entrepreneurship, and that in the case of opportunity entrepreneurship, financial capital exhibits increasing marginal returns. However, inequality does impact the magnitude of marginal returns. Additionally, our statistical analysis provides quantitative support to extant literature arguing that higher levels of economic inequality foster both types of entrepreneurship albeit having a stronger impact on necessity entrepreneurship, and that human and financial capital have distinct effects on entry into necessity versus opportunity entrepreneurship. All these findings have pertinent policy implications and shed light on the under-researched role of inequality on entrepreneurship.
Adverse Selection in the Children’s Health Insurance Program
Authors: Morrisey Michael A. , Blackburn Justin , Becker David J. , Sen Bisakha , Kilgore Meredith L. , Caldwell Cathy , Menachemi Nir
Published: July 2015

This study investigates whether new enrollees in the Alabama Children’s Health Insurance Program have different claims experience from renewing enrollees who do not have a lapse in coverage and from continuing enrollees. The analysis compared health services utilization in the first month of enrollment for new enrollees (who had not been in the program for at least 12 months) with utilization among continuing enrollees. A second analysis compared first-month utilization of those who renew immediately with those who waited at least 2 months to renew. A 2-part model estimated the probability of usage and then the extent of usage conditional on any utilization. Claims data for 826 866 child-years over the period from 1999 to 2012 were used. New enrollees annually constituted a stable 40% share of participants. Among those enrolled in the program, 13.5% renewed on time and 86.5% of enrollees were late to renew their enrollment. In the multivariate 2-part models, controlling for age, gender, race, income eligibility category, and year, new enrollees had overall first-month claims experience that was nearly $29 less than continuing enrollees. This was driven by lower ambulatory use. Late renewals had overall first-month claims experience that was $10 less than immediate renewals. However, controlling for the presence of chronic health conditions, there was no statistically meaningful difference in the first-month claims experience of late and early renewals. Thus, differences in claims experience between new and continuing enrollees and between early and late renewals are small, with greater spending found among continuing and early renewing participants. Higher claims experience by early renewals is attributable to having chronic health conditions.
Community Support and Adolescent Girls’ Vulnerability to HIV/AIDS
Authors: Underwood Carol , Schwandt Hilary M.
Published: July 2015

Girls are vulnerable to HIV in part because the social systems in which they live have failed to support and protect them. The goal of this research was to develop a viable supportive community index and test its association with intermediate variables associated with HIV risk across 16 communities in Botswana, Malawi, and Mozambique. This cross-sectional survey with separate samples randomly drawn in each country (2010) yielded a total sample of 1,418 adolescent girls (aged 11–18). Multilevel, multivariate logistic regression, while controlling for vulnerability, age, religion, and residence, found that an increase in supportive community index is positively associated with the odds of indicating improved community support for girls and with the confidence to refuse unwanted sex with a boyfriend across the three countries, as well as with self-efficacy to insist on condom use in Botswana and Mozambique. Program implementers and decision makers alike can use the supportive community index to identify and measure structural factors associated with girls’ vulnerability to HIV/AIDS; this will potentially contribute to judicious decision making regarding resource allocation to enhance community-level, protective factors for adolescent girls.
Indolo[3,2-b]carbazole-based poly(arylene ethynylene)s
Authors: Grigoras Mircea , Negru Oana Iuliana , Solonaru Ana Maria
Published: July 2015

A novel family of indolo[3,2-b]carbazole (ICZ)-based polymers was designed and synthesized using Sonogashira cross-coupling reaction between three bisbromine indolo[3,2-b]carbazoles and 1,4-diethynylbenzene. The new polymers have an arylene ethynylene structure with ICZ moiety interconnected in the main chain by 2,8-, 3,9- or 6,12- positions. The polymers were obtained as partially soluble materials, in chlorinated, aromatic and aprotic polar solvents. The structure of the polymers was studied by spectroscopic methods such as Fourier transform infrared, proton and carbon-13 nuclear magnetic resonance, ultraviolet–visible and photoluminescence spectroscopies, thermogravimetry and molecular weights determined by gel permeation chromatography. Electrochemical properties were investigated by cyclic voltammetry using films cast on platinum disc working electrode. Optical and electronic properties were discussed from the viewpoint of the connection positions of ICZ units in the polymer chain.
Organic–inorganic hybrid nanomaterials based on inorganic oxides and a mesomorphic polyazomethine
Authors: Perju Elena , Ghimpu Lidia , Hitruc Gabriela , Harabagiu Valeria , Bruma Maria , Marin Luminita
Published: July 2015

Organic–inorganic hybrid materials have been obtained by impregnating a mesomorphic polyazomethine into a porous inorganic matrix of zinc oxide (ZnO), tin dioxide (SnO2), or mixed ZnO/SnO2. The porous inorganic matrix has been obtained by magnetron sputtering technique and proved a very high crystallinity degree. The resulting hybrid materials were characterized from morphological and optical points of view by scanning electron microscopy, atomic force microscopy, and ultraviolet-visible and photoluminescence spectroscopy. The inorganic matrix itself exhibited a highly rough surface, which became smoother after polymer impregnation, indicating its complete coverage. The violet emission of the separate inorganic and organic components turned into a blue and green light emission, respectively, of the hybrid materials, suggesting the possibility to modulate the color of emitted light by the simple choice of the inorganic matrix. Considerations with regard of interface phenomena that prompted the photophysical changes of the hybrid materials were done.
Thermal behavior, surface energy analysis, and hemocompatibility of some polycarbonate urethanes for cardiac engineering
Authors: Gradinaru L. M. , Ciobanu C. , Vlad S , Drobota M. , Butnaru M. , Saint-Pierre G.
Published: July 2015

The understanding of basic surface properties and the relationships between temperature and the configuration of the polymer surface are the key to further understand the first interaction mechanism of the polymer with the body. To this end, some poly(carbonate tetramethylene ether)urethane (PCEU), poly(carbonate siloxane tetramethylene ether)urethane (PCSiEU), and their 1:1 gravimetric mixture (PCEU/PCSiEU) membranes were prepared. In order to establish the relationships between temperature and the chemical structure of polymer surface, the polyurethane (PU) membranes were analyzed by attenuated total reflectance–Fourier transform infrared spectroscopy. The temperature has a significant influence on these PU surface structures. Surface characteristics such as wettability and surface free energy were also analyzed since the interaction between biomaterials and blood occurs at their interface. The preliminary cytotoxicity screening showed no cytotoxicity of these PU membranes. The PU samples do not accelerate the clot formation mechanisms under the tested conditions. The results suggest that these PU membranes are promising materials for the preparation of cardiovascular scaffolds.
Coordination polymer of copper with a silicon-containing Schiff base
Authors: Zaltariov Mirela-Fernanda , Cazacu Maria , Vlad Angelica , Sacarescu Liviu , Shova Sergiu
Published: July 2015

A Schiff base was prepared by condensation reaction of 2,6-diformyl-4-methylphenol with trimethylsilyl-methyl- p-aminobenzoate and it was further used, without isolation, as a ligand for copper (Cu(II)) ions. The structure of the resulting coordination complex was evidenced by spectral techniques (Fourier transform infrared spectroscopy, nuclear magnetic resonance and ultraviolet-visible spectroscopy) and by single crystal X-ray diffraction, which revealed a covalent one-dimensional (1D) structure where neutral molecular units (Cu(II) coordination polymer [CuL2]) are linked through the bridging oxygen atoms. The 1D polymeric chains are associated by intermolecular C–H···O hydrogen bonding to form two-dimensional supramolecular layers. The polymeric nature of the compound was also supported by the presence of glass transition in differential scanning calorimetry trace. This coordination polymer forms spherical aggregates in a nonpolar medium (hexane) as was emphasized by transmission electron microscopy image taken on the film remained after solvent evaporation. The thermogravimetrical analysis indicates a good stability for the Cu(II) coordination polymer and the biological tests revealed good antibacterial and antifungal activities.
Physical and thermal properties of poly(ethylene terephthalate) fabric coated with electrospun polyimide fibers
Authors: Butnaru Irina , Serbezeanu Diana , Bruma Maria , Sava Ion , Gaan Sabyasachi , Fortunato Giuseppino
Published: July 2015

Two analogous polyimides (PIs) containing flexible isopropylidene units were prepared. One was based on 4,4′-oxydiphthalic anhydride and 4,4′-(4,4′-isopropylidenediphenyl-1,1′-diyldioxy) dianiline and the other was based on 4,4′-(4,4′-isopropylidenediphenoxy) bis(phthalic anhydride) and bis(3-aminophenyl) methyl phosphine oxide. The ability of these two PIs to form uniform nanoscaled fibers was investigated by electrospinning technique. At optimal spinning conditions, PI fibers were electrospun onto the surface of woven poly(ethylene terephthalate) (PET) support to form a bilayer composite structure. These new fabric systems were analyzed regarding morphology, air permeability, wetting properties, and thermal stability. It was expected that the new PET/PI mats would possess enhanced properties compared with the initial woven PET fibers due to the excellent properties of PIs. Experimental results showed that PET woven substrate coated with electrospun PI fibers had improved values of air permeability, water contact angle and thermal stability when compared with the initial woven PET fibers.
Synthesis, characterization, and solution behavior of pullulan functionalized with tertiary amino groups
Authors: Constantin Marieta , Asmarandei Ionela , Filimon Anca , Fundueanu Gheorghe
Published: July 2015

The synthesis of cationic amphiphilic pullulan having dimethylaminopropyl groups was performed in dimethyl sulfoxide using N, N′-carbonyldiimidazole as activator. The pullulan derivatives with three different substitution degrees were characterized by FTIR, 1H and 13C NMR, elemental analysis, and conductometric titrations. The aggregates characteristics were determined by steady-state fluorescence (critical aggregation concentration and polarity) and capillary viscometry measurements. Their behavior in aqueous dilute and semidilute solutions was investigated by viscosimetric experiments and fluorescence technique over the concentration range of 0.01–10 g dL−1, as a function of the degree of substitution with pendant groups. Intrinsic viscosity determined using Wolf equations provided information on the conformation of polymer chains. The results highlight the appearance of intramolecular and intermolecular aggregates and the dependence of their characteristics on the degree of substitution with pendant groups.
Preparation approach effect on polyurethane/montmorillonite nanocomposites characteristics
Authors: David Geta , Drobota Mioara , Simionescu Bogdan C.
Published: July 2015

Segmented polyurethane/montmorillonite (MMT) nanocomposites have been obtained by solvent casting or in situ polymerization approaches using poly(tetramethyleneglycol), α,ω-dihydroxylated poly(2-alkyl-2-oxazoline), 4,4′-methylenebis-(phenyl isocyanate) and MMT. The influence of the preparation method on the characteristics of the resulted materials was studied by means of spectral and thermal analysis, X-ray diffraction, scanning electronic microscopy, and dynamic-mechanical analysis.
The New Curriculum in Post-Apartheid South Africa
Authors: Kros Cynthia
Published: July 2015

This paper provides some of the political context for the development of the school curriculum in the period after apartheid, pointing out that the curriculum that was drafted originally under the rubric ‘Curriculum 2005’ had to be substantially modified without loss of political face because of the practical difficulties of implementation. The new version of the curriculum still bears discursive traces of the old, most notably with regard to globalisation, but has also been subject to diverse intellectual influences. The paper pays special attention to the treatment of History in the curriculum, and to the way in which it tries to present race.
Tilting at Windmills
Authors: Fennell Shailaja
Published: July 2015

There are many obstacles to the successful provision of universal primary and secondary education. The failure of State schools to provide adequate schooling is a serious hindrance to achieving the international goal of Education for All. Non-State providers of education are regarded as an alternative but the variation in the quality of education provided is a growing concern. Educational partnerships between the public and private sector have been regarded as a way out of this impasse in the United States and Western Europe and there has been considerable debate about the economic and political implications of these public-private partnerships (PPPs). Disentangling the economic and political dimensions of provision would further our understanding of these new models of educational provision. This paper sets out a typology of identifying the economic and political aspects of provision through using the Hirschmanian concepts of ‘exit’ and ‘voice’. The idea of ‘exit’ draws on the mainstream economic understanding of free entry and exit, with the latter occurring when individuals are no longer satisfied with what is on offer in the market. The term ‘voice’ is used to denote political activity undertaken by an individual to ensure the continued provision of a good and/or the quality of the good. Conceptualising educational provision in relation to exit and voice permits the examination of how the role of the market and community affects access to and the quality of education. Educational initiatives by State and non-State providers in India are mapped onto this typology to gain an understanding of how the new models of education, such as PPPs, would affect the current provision of education.
Phonological Awareness and Literacy Acquisition in Telugu-speaking, Normal-hearing and Hearing-impaired Children
Authors: Vasanta D.
Published: July 2015

Phonological awareness is a form of metalinguistic awareness that has been studied intensively because of its relation to schooling and the acquisition of literacy. However, much of this research has been confined to languages with alphabetic scripts such as English. It has been noted that children who are born deaf or acquire deafness very early in life before they have learned their native language and those who are raised in an aural-oral environment do develop some awareness of letter-sound mappings and other spelling regularities by drawing on information from lip-reading and residual hearing. Such children nevertheless have to do a lot of catching up in language in order to be effectively integrated in schoolwork. There is limited published evidence about the role of phonological awareness in the acquisition and mastery of languages with non-alphabetic writing systems associated with some of the Indian languages. Specific literacy acquisition problems faced by hearing-impaired children studying in regular schools in India have not been examined within a linguistic perspective. This paper describes the results of an empirical study involving 15 normal hearing children (average age: 10 years) and 15 hearing-impaired children (average age: 14 years), all native speakers of Telugu studying in Telugu-medium schools. Using specially designed syllable manipulation tasks, the quantitative and qualitative differences in the processing of the written word of the two groups were examined. Some of the theoretical and clinical implications of the results are discussed in this paper.
Administration of Secondary Education
Authors: Tyagi R. S.
Published: July 2015

The present paper is based on a country wide survey of administration of school education in India. The paper discusses the status of policy reforms over the years and their implications on educational administration. It notes that administrative structures and practices of secondary education have failed to respond to the increases in enrolment and monitoring of quality. It identifies some key areas of structure and function that need urgent reform in the context of universalising secondary education and the launch of the Rashtriya Madhyamik Shiksha Abhiyan.
Quality in Education
Authors: Kumar Krishna
Published: July 2015

Since the 1990s, programmes aimed at universalising elementary eduction in India have increasingly dichotomised ‘quality’ and ‘equality’ and heightened, a view of education which is essentially instrumental. The paper argues that this opposition is mistaken and that equality itself requires a nuanced approach which reflects the quality of education as an involvement in the long-term growth of the person. An example of how a school may be knowledgeably structured for educational quality, given the social reality of entrenched gender inequality, is discussed.
Quality and Inequality in Indian Education
Authors: Velaskar Padma
Published: July 2015

The paper locates educational policy in a wider socio-historical and political perspective and aims at an ideological deconstruction of policy change with a specific focus on the equality–quality conundrum in elementary education in India. It attempts to critically decode changes in notions and practices of equality and quality in national and international policy prescription, highlighting aspects of ideological contexts, power asymmetries and state dynamics and examines basic shifts in policy discourse and intent. The paper is organised in four parts. The first two parts take a broad historical overview to examine notions of equality and quality, articulated in texts and discussions pertaining to the two national educational policies and in policy initiatives introduced by the Indian state under neoliberal, global hegemonic influence. The interactive impact of educational restructuring and structures of stratification as reflected in the aggravation of key caste, class, gender and ethnic inequalities is captured in the third part of the paper. The final part of the paper draws attention to dilutions and contradictions inherent in recent policy shifts to argue that any meaningful notion of quality education for the poor is impossible to attain in the present context. It unravels the politics of quality.
Educational Quality and Social Inequality
Authors: Pappu Rekha , Vasanta D.
Published: July 2015

It is argued that the perception of existing inequality within the field of school education gave rise to the language of rights, but that normative notions of childhood underpinning educational discourses have not been sufficiently problematised. The paper makes a case for productive convergence between the discourses of quality and inequality by drawing on the observations from a study of government schools in Andhra Pradesh. Specifically, the paper foregrounds the need for reflecting on the tacit agreement that exists within the education system about bracketing off questions of socio-cultural inequality when discussing issues of quality and learning goals on the one hand, and the compartmentalisation of the language of rights on the other hand such that adequate attention has not yet been paid to questions of educational quality.
Evidence-Based Practices for Learners With Severe Intellectual Disability
Authors: Courtade Ginevra R. , Test David W. , Cook Bryan G.
Published: July 2015

Because of their highly intensive and variable learning needs, learners with severe intellectual disability present significant challenges to special educators and other stakeholders in terms of selecting and implementing effective instructional practices. Although scholars have made considerable progress in conducting and synthesizing research necessary to identify evidence-based practices (EBPs), much work remains to enable evidence-based reforms to broadly improve instruction and outcomes for learners with severe intellectual disability. In this article, we describe the importance of evidence-based reforms for learners with severe intellectual disability; discuss advances in the identification of EBPs for these learners, including a summary of the interventions identified as EBPs for this population in the professional literature and by online resources; and conclude with recommendations for improving the identification and implementation of EBPs for this population.
Gendered pathways to hukou status mobility in China
Authors: Xiang Jun
Published: July 2015

One of China’s most important institutions is its hukou system, a registry that assigns benefits to household members based on rural or urban location. Changes in hukou status are not easy, but hukou mobility from rural to urban status is an important path to upward social mobility in China. While this hukou conversion is well covered in the literature pertaining to other research, previous studies have failed to solve the puzzle as to why this status change is achieved more often by rural women than rural men, even though these women are less likely to have more education, Communist Party membership, or military service – the three best-known predictors of hukou mobility in China. I believe this lapse in previous studies is because researchers assume that mobility is gender-neutral and then only examine the predictors of hukou conversion that favor rural men. These studies overlook a crucial predictor that probably favors women – marriage – and thus their findings are subject to an omitted variable bias. Using the Chinese General Social Survey (CGSS) 2008, a nationally representative dataset with unique information on the hukou conversion process, this paper explicitly brings the gender perspective into hukou mobility studies and finds gender-specific pathways in the hukou conversion process. The patterns of gendered divergence in hukou mobility reflect how the socioeconomic status of rural migrants is shaped by the institutional, economic, and sociocultural factors that impose constraints and provide opportunities in China.
Interactome analysis brings splicing into focus
Authors: Dominguez Daniel , Burge Christopher B.
Published: July 2015

The spliceosome is a huge molecular machine that assembles dynamically onto its pre-mRNA substrates. A new study based on interactome analysis provides clues about how splicing-regulatory proteins modulate assembly of the spliceosome to either activate or repress splicing.

Please see related Research article: http://www.genomebiology.com/2015/16/1/119/abstract