bluuebunny/crossref_metadata_2025 huggingface dataset:
Systematic study of epitaxy growth uniformity in a specific MOCVD reactor
Authors: Fang Haisheng , Zhang Zhi , Pan Yaoyu , Ma Ronghui , Liu Sheng , Wang Mengying
Published: October 2014

Gallium nitride (GaN) is a direct bandgap semiconductor widely used in bright light‐emitting diodes (LEDs). Thin‐film GaN is grown by metal‐organic chemical vapour deposition (MOCVD) technique. Reliability, efficiency and durability of LEDs are influenced critically by the quality of GaN films. In this report, a systematic study has been performed to investigate and optimize the growth process. Fluid flow, heat transfer and chemical reactions are calculated for a specific close‐coupled showerhead (CCS) MOCVD reactor. Influences of reactor dimensions and growth parameters have been examined after introducing the new conceptions of growth uniformity and growth efficiency. It is found that GaN growth rate is mainly affected by the concentration of (CH3)3Ga:NH3 on the susceptor, while growth uniformity is mainly influenced by the recirculating flows above the susceptor caused by natural convection. Effect of gas inlet temperature and the susceptor temperature over the growth rate can be explained by two competing mechanisms. High growth efficiency can be achieved by optimizing the reactor design.
A novel magneto‐impedance sensor model based on the zeros of Bessel functions
Authors: Vargas‐Bernal Rafael , De la Cruz Blas Carlos A. , Gómez‐Polo Cristina
Published: October 2014

Nowadays, the design of magneto‐impedance (MI) sensors requires the development of lumped circuit models that can be simulated through equivalent impedance circuits relied on Bessel functions. A new impedance model based on Senani's equivalent using the zeros of Bessel functions is developed in this paper. The model allows to describe the impedance as a transfer function that can be easily synthesized by means of current conveyor circuits and passive elements. The mathematical representation was verified under simulation of transfer functions involving different number of poles and zeros. Moreover, the model has been verified using SPICE simulations and measurement results from a fabricated prototype demonstrating its scope and validity. Finally, a study of finite tracking errors of CCIIs used in the implementation of magneto‐impedance sensor has been realized. Copyright © 2014 John Wiley & Sons, Ltd.
Psychosocial factors associated with bulimia nervosa during pregnancy: An internal validation study
Authors: Watson Hunna J. , Von Holle Ann , Knoph Cecilie , Hamer Robert M. , Torgersen Leila , Reichborn‐Kjennerud Ted , Stoltenberg Camilla , Magnus Per , Bulik Cynthia M.
Published: October 2014

Objective

The aim of this paper was to internally validate previously reported relations (Knoph Berg et al., Aust N Z J Psychiatry, 42, 396–404, 2008) between psychosocial factors and bulimia nervosa (BN) outcomes during pregnancy.

Method

This study is based on the Norwegian Mother and Child Cohort Study (MoBa) conducted by the Norwegian Institute of Public Health. Participants were women enrolled during pregnancy (N = 69,030). Internal validity was evaluated by way of bootstrapped parameter estimates using the overall sample and a split sample calibration approach.

Results

Bootstrap bias estimates were below the problematic threshold, and extend earlier findings (Knoph Berg et al., Aust N Z J Psychiatry, 42, 396–404, 2008) by providing support for the validity of the models at the population level of all pregnant women in Norway. Bootstrap risk ratios indicated that prevalence, incidence, and remission of BN during pregnancy were significantly associated with psychosocial factors. The split sample procedure showed that the models developed on the training sample did not predict risks in the validation sample.

Discussion

This study characterizes associations between psychosocial exposures and BN outcomes among pregnant women in Norway. Women with lifetime and current self‐reported psychosocial adversities were at a much higher risk for BN during pregnancy. Psychosocial factors were associated with BN remission during pregnancy, inviting the prospect of enhancing therapeutic interventions. We consider the findings in the context of reproducibility in science. © 2014 Wiley Periodicals, Inc. (Int J Eat Disord 2015; 48:654–662)
Genetic signs of multiple colonization events in Baltic ciscoes with radiation into sympatric spring‐ and autumn‐spawners confined to early postglacial arrival
Authors: Delling Bo , Palm Stefan , Palkopoulou Eleftheria , Prestegaard Tore
Published: October 2014

Presence of sympatric populations may reflect local diversification or secondary contact of already distinct forms. The Baltic cisco (Coregonus albula) normally spawns in late autumn, but in a few lakes in Northern Europe sympatric autumn and spring‐ or winter‐spawners have been described. So far, the evolutionary relationships and taxonomic status of these main life history forms have remained largely unclear. With microsatellites and mtDNA sequences, we analyzed extant and extinct spring‐ and autumn‐spawners from a total of 23 Swedish localities, including sympatric populations. Published sequences from Baltic ciscoes in Germany and Finland, and Coregonus sardinella from North America were also included together with novel mtDNA sequences from Siberian C. sardinella. A clear genetic structure within Sweden was found that included two population assemblages markedly differentiated at microsatellites and apparently fixed for mtDNA haplotypes from two distinct clades. All sympatric Swedish populations belonged to the same assemblage, suggesting parallel evolution of spring‐spawning rather than secondary contact. The pattern observed further suggests that postglacial immigration to Northern Europe occurred from at least two different refugia. Previous results showing that mtDNA in Baltic cisco is paraphyletic with respect to North American C. sardinella were confirmed. However, the inclusion of Siberian C. sardinella revealed a more complicated pattern, as these novel haplotypes were found within one of the two main C. albula clades and were clearly distinct from those in North American C. sardinella. The evolutionary history of Northern Hemisphere ciscoes thus seems to be more complex than previously recognized.
Acyl‐Functionalized Molybdenum Compounds [(η3‐C3H5)(η5‐Cp′)Mo(CO)2]: An Experimental Study Including the X‐ray Structure of a Rare endo Conformer
Authors: Schejbal Jiří , Honzíček Jan , Vinklárek Jaromír , Erben Milan , Růžičková Zdeňka
Published: October 2014

A series of new acyl‐functionalized molybdenum(II) complexes [(η3‐C3H5)(η5‐C5H4COR)Mo(CO)2] have been successfully synthesized and crystallographically characterized, and the relationship between the reactivity and electronic properties of these organometallic compounds has been studied in detail. The X‐ray analysis revealed [(η3‐C3H5)(η5‐C5H4COCF3)Mo(CO)2] to exist as a rare endo conformer, the first time that this structure has been observed in the crystal lattice of a [(η3‐C3H5)(η5‐Cp′)Mo(CO)2] (Cp′ = substituted Cp) complex without any disorder. It has also been demonstrated that the derivatives bearing very strong electron‐withdrawing acyl groups (e.g., ‐CHO, ‐COCF3) show different outcomes in the protonation reactions compared with the parent cyclopentadienyl compound or derivatives bearing less electron‐withdrawing groups (e.g., ‐COMe, ‐COPh). This study has also revealed the increased reactivity of the formyl derivative [(η3‐C3H5)(η5‐C5H4CHO)Mo(CO)2] towards aromatic amines. An IR spectroscopic analysis revealed that the aldimine‐functionalized products formed very quickly even under the mild conditions that fulfill the basic rules of click chemistry.
A Versatile Protocol for the Synthesis of Pyrazolyl‐Substituted Pyridinium and Guanidinium Salts from Pyridone and Urea Derivatives
Authors: Echterhoff Antje K. C. , Yogendra Sivathmeehan , Kösters Jutta , Fischer Roland , Weigand Jan J.
Published: October 2014

The trication (pyr3P2)3+ (1+, pyr = 3,5‐dimethylpyrazolyl) is used as a convenient pyrazolyl‐transfer reagent to convert 2‐pyridones, 4‐pyridones, and urea derivatives to pyrazolyl‐substituted pyridinium or guanidinium triflate salts. This conversion represents a new, efficient, and highly functional‐group‐compatible approach that yields the desired products conveniently and in high yields. Typically, this reaction proceeds by exchange of the carbonyl oxygen atom of the substrate for a pyrazolyl moiety. However, for the structurally related 3‐hydroxypyridines, a different reaction pathway occurs to give tripyridyl phosphites. The outcome of the reaction can be explained by the lactam–lactim tautomerism of the substrate and is discussed in detail. All reaction products were fully characterized by elemental analysis and multinuclear NMR, IR, and Raman spectroscopy, and the structural arrangements of most of the products were confirmed by X‐ray crystallography analysis.
Design and Synthesis of 3‐Trifluoromethyl‐3H‐pyrazoles and Further Investigations of Their Transformation to 1H‐Pyrazoles
Authors: Sha Qiang , Liu Haixuan , Wei Yunyang
Published: October 2014

An efficient intramolecular cycloaddition strategy for the synthesis of trifluoromethyl‐substituted 3H‐pyrazoles was developed. Subsequently, their wide applications were demonstrated: they (1) react with dioxane by a radical process and (2) undergo [1,5] sigmatropic rearrangements. These applications are useful as the products were obtained in high yields and with excellent regioselectivity.
Mechanistic Elucidation of the 2‐Norbornyl to 1,3‐Dimethylcyclopentenyl Cation Isomerization
Authors: Jalife Said , Martínez‐Guajardo Gerardo , Zavala‐Oseguera Claudia , Fernández‐Herrera María A. , von Ragué Schleyer Paul , Merino Gabriel
Published: October 2014

Extremely complicated isomerization mechanisms for the isomerization of the 2‐norbornyl to 1,3‐dimethylcyclopentenyl cation observed in the gas phase have been elucidated through Born–Oppenheimer molecular dynamics simulations and ab initio computations. These quantum chemical explorations revealed that there are two viable complex rearrangement pathways. The longer pathway involves consecutive ring‐openings with the formation of acyclic allylic cation intermediates. Although these are avoided in the shorter pathway, both routes are feasible, because the energy barriers of their first steps differ by only 1.0 kcal/mol. Both pathways eventually converge to the same methylcyclohexenyl cation, which undergoes ring contraction and methyl and hydride shifts to yield the C7H11+ global minimum, namely the 1,3‐dimethylcyclopentenyl cation.
Investigation into the dehydration process of oily sludge by fry‐drying method
Authors: Zhang Ke , Zhu Jianhua , Zhou Yong , Wu Bencheng
Published: October 2014

This study investigated the oily sludge water loss and oil uptake phenomenon during the fry‐drying process. A cylindrical sample of oily sludge was added to the preheated spent lubricating oil of vehicle. A diffusion model and a first‐order kinetic model were proposed to predict the water and oil content, respectively, of the oily sludge sample. The drying rate and oil content of the sample increased with the increase in the temperature of the frying oil and the initial water content of the sample, as well as with the decrease in the sample diameter. When the initial water content of the sample decreased from 0.4093 to 0.3512 g/g and 0.3081 g/g, the final oil content decreased by 12.24 and 20.11%, respectively. The accuracy and universality of both models were evaluated by average relative deviation (ARD) and maximum relative deviation (MRD) under 10 experimental conditions. The ARD and MRD of the sample water content were 4.72 and 8.66%, respectively, whereas those of the oil content were 6.56 and 8.75%, respectively. © 2014 American Institute of Chemical Engineers Environ Prog, 2014 34: 681–688, 2015
Apparatus for the vertical orientation cone calorimeter testing of flexible polyurethane foams
Authors: Galaska Mary L. , Morgan Alexander B. , Schenck Kathleen A. , Stalter John G.
Published: October 2014

Of concern to regulators and fire safety engineers is how flexible polyurethane foam drips and flows during burning. Specifically, flexible polyurethane foam forms a burning ‘pool’ of liquid as the foam decomposes, which can lead to accelerated flashover events. To fully study this phenomenon where the ‘pool fire’ accelerates heat release, large‐scale tests like the furniture calorimeter (American Society of Testing and Materials (ASTM) E1537) are used, and no small‐scale technique exists. In this paper, we present our work in developing a new sample holder that works with a bench‐scale heat release test, the cone calorimeter (ASTM E1354). The holder was built upon designs developed by the National Institute of Standards and Technology, which placed the foam in a cage in a vertical orientation during cone calorimeter testing. In this paper, we show the schematics for this test apparatus, as well as results obtained with this apparatus on four different flexible foams (shape memory and high‐density foam, flame retarded and non‐flame retarded). We compare the results from the vertical testing with that obtained via traditional horizontal ASTM E1354 testing. The advantages and disadvantages of this new apparatus are discussed in this paper. Copyright © 2014 John Wiley & Sons, Ltd.
A Fractionally Cointegrated VAR Analysis of Price Discovery in Commodity Futures Markets
Authors: Dolatabadi Sepideh , Nielsen Morten Ørregaard , Xu Ke
Published: October 2014

In this paper, we apply the recently developed fractionally cointegrated vector autoregressive (FCVAR) model to analyze price discovery in the spot and futures markets for five non‐ferrous metals (aluminum, copper, lead, nickel, and zinc). The FCVAR model allows for long memory (fractional integration) in the equilibrium errors, and, following Figuerola‐Ferretti and Gonzalo (2010), we allow for the existence of long‐run backwardation or contango in the equilibrium as well, that is, a non‐unit cointegration coefficient. Price discovery can be analyzed in the FCVAR model by a relatively straightforward examination of the adjustment coefficients. In our empirical analysis, we use the data from Figuerola‐Ferretti and Gonzalo (2010), who conduct a similar analysis using the usual (non‐fractional) CVAR model. Our first finding is that, for all markets except copper, the fractional integration parameter is highly significant, showing that the usual, non‐fractional model is not appropriate. Next, when allowing for fractional integration in the long‐run equilibrium relations, fewer lags are needed in the autoregressive formulation, further stressing the usefulness of the fractional model. Compared to the results from the non‐fractional model, we find slightly more evidence of price discovery in the spot market. Specifically, using standard likelihood ratio tests, we do not reject the hypothesis that price discovery takes place exclusively in the spot (futures) market for copper, lead, and zinc (aluminum and nickel). © 2014 Wiley Periodicals, Inc. Jrl Fut Mark 35:339–356, 2015
Investor Beliefs and the Demand Pressure on Index Options in Taiwan
Authors: Pan Ging‐Ginq , Shiu Yung‐Ming , Wu Tu‐Cheng
Published: October 2014

The effects of demand pressure on option prices have already been well documented within the extant literature; however, little appears to be known with regard to where the demand pressure on options originates. We set out in the present study to examine the ways in which investor beliefs affect the demand pressure on TAIEX options, employing forward‐looking risk‐neutral index distributions to evaluate such beliefs. Our examination of 2005–2012 high‐frequency data reveals that with an increase in the level of market fear amongst investors, there will be a corresponding rise in the demand for options, with greater pessimism amongst investors resulting in weaker (stronger) demand for calls (puts). Furthermore, during the 2008 financial crisis, the soaring market atmosphere, and the fears of a market crash which soon followed, clearly had dominating effects on demand pressure, with an increase (reduction) in demand pressure for call (put) options being discernible during the bullish sentiment period, and vice versa amid the subsequent fears of a market crash. © 2014 Wiley Periodicals, Inc. Jrl Fut Mark 35:1117–1132, 2015
Animal models for percutaneous absorption
Authors: Jung Eui Chang , Maibach Howard I.
Published: October 2014

Animal models are important tools to predict human in vivo percutaneous absorption/penetration. Monkey, pig, rat, rabbit, guinea pig, hairless rodents, such as hairless rat, hairless mouse, hairless guinea pig and hairless dog, are among the most used animals for this purpose. Each animal model has its own advantages and weakness or limitation. To better correlate animal data with human skin absorption, we need to be familiar with each animal model's characteristics as well as experimental method and condition. We reviewed the original papers published after 1993 that described permeability of both animal skin and human skin. It showed that monkey, pig and hairless guinea pig are more predictive of human skin absorption/penetration and common laboratory animals, such as rat, rabbit, guinea pig, generally overestimate human skin absorption/penetration. Copyright © 2014 John Wiley & Sons, Ltd.
Essential Role of Osterix for Tooth Root but not Crown Dentin Formation
Authors: Zhang Hua , Jiang Yong , Qin Chunlin , Liu Ying , Ho Sunita P , Feng Jian Q
Published: October 2014

Tooth is made of crown and root. It is widely believed that dentin formation in crown and root uses the same regulatory mechanism. However, identification of nuclear factor 1 C (NFIC)'s unique function in determining root but not crown dentin formation challenges the old thinking. In searching for the target molecules downstream of NFIC, we unexpectedly found a sharp reduction of osterix (OSX), the key transcription factor in skeleton formation, in the Nfic knockout (Nfic-KO) tooth root. We then demonstrated a dose-dependent increase of Osx in the odontoblast cell line due to a transient transfection of Nfic expression plasmid. Studies of global and conditional Osx-KO mice revealed no apparent changes in the crown dentin tubules and dentin matrix. However, the OSX conditional KO (cKO) mice (crossed to the 2.3-kb collagen type 1 [Col1]-Cre) displayed an increase in cell proliferation but great decreases in expressions of root dentin matrix proteins (dentin matrix protein 1 [DMP1] and dentin sialophosphoprotein [DSPP]), leading to an inhibition in odontoblast differentiation, and short, thin root dentin with few dentin tubules. Compared to the Nfic-KO tooth, which contains essentially no dentin tubules and remains in a “root-less” status at adult stages, the Osx-cKO root phenotype had partially improved at the late stage, indicating that other factors can compensate for OSX function. Thus, we conclude that OSX, one of the key downstream molecules of NFIC, plays a critical role in root, but not crown, formation. © 2014 American Society for Bone and Mineral Research.
Scratching activates microglia in the mouse spinal cord
Authors: Zhang Ying , Dun Siok L. , Chen Yi‐Hung , Luo Jin J. , Cowan Alan , Dun Nae J.
Published: October 2014

This study tested the hypothesis that repetitive scratching provoked by two known pruritogens, compound 48/80 and 5′‐guanidinonaltrindole (GNTI), is accompanied by activation of microglial cells in the mouse spinal cord. Immunohistochemical studies revealed that the complement receptor 3, also known as cluster determinant 11b (CD11b), a cell surface marker of microglial cells, was upregulated in the spinal cord 10–30 min after a subcutaneous (s.c.) injection of compound 48/80 (50 μg/100 μl) or GNTI (0.3 mg/kg) to the back of the mouse neck. Numerous intensely labeled CD11b‐immunoreactive (CD11b‐ir) cells, with the appearance of hypertrophic reactive microglia, were distributed throughout the gray and white matter. In contrast, weakly labeled CD11b‐ir cells were distributed in the spinal cord from mice injected with saline. Western blots showed that CD11b expression levels were significantly increased in spinal cords of mice injected s.c. with either pruritogen, reached a peak response in about 30 min, and declined to about the basal level in the ensuing 60 min. In addition, phospho‐p38 (p‐p38) but not p38 levels were upregulated in spinal cords from mice injected with compound 48/80 or GNTI, with a time course parallel to that of CD11b expression. Pretreatment of the mice with nalfurafine (20 µg/kg; s.c.), a κ‐opioid receptor agonist that has been shown to suppress scratching, reduced CD11b and p‐p38 expression induced by either pruritogen. The results demonstrate, for the first time, that scratch behavior induced by the pruritogens GNTI and compound 48/80 is accompanied by a parallel activation of microglial cells in the spinal cord. © 2014 Wiley Periodicals, Inc.
An analysis of rainfall across the British Isles in the 1870s
Authors: Burt T. P. , Jones P. D. , Howden N. J. K.
Published: October 2014

Monthly records for the period 1871–1970 from 91 stations across the British Isles are used to place very high rainfall totals during the 1870s, 1872 and 1876–1877 in particular, in context. Comparisons are drawn with 2012 and the winter of 2013–2014, both of which were exceptionally wet in parts of the British Isles. Traditional Lamb weather type count and objective measures of atmospheric circulation obtained from reanalysis of surface pressure charts are used to classify the weather conditions under which these very high rainfall totals were generated. The normally wettest locations in the British Isles, i.e. the uplands in the north and west, were not unusually wet in the 1870s, whereas locations with extremely high rainfall totals (relative to mean annual rainfall) tended to be further south and east in the lowlands. These exceptionally high totals were associated with a high frequency of cyclonic weather types and high scores for atmospheric vorticity; at the same time, the frequency of anticyclonic weather and of westerly winds tended to be very low. The winter of 2013–2014, remarkably wet in southern England, was somewhat different in that both the frequency of westerly air flow and the resultant flow were very high and so were vorticity and the frequency of cyclonic weather types; the year 2012 experienced similar atmospheric conditions. The results confirm the importance of cyclonic weather for large rainfall totals across much of the British Isles; strong westerly winds seem only to favour the uplands and northwest coastal locations.
Changes in heavy precipitation and floods in the upstream of the Beijiang River basin, South China
Authors: Wu Chuanhao , Huang Guoru
Published: October 2014

The objective of this study was to investigate the changes in heavy precipitation and floods and the causes of flood risk changes in the Beijiang River basin in southern China. Peak flow, daily discharge, and precipitation data from 1969 to 2011 were examined. Trends were calculated using Sen's slope estimator. The statistical significance of the observed trends was checked with the Mann–Kendall method. Change points were detected using the Pettitt test and moving T‐test methods. The hydrological periodicity was revealed by wavelet transformation. The results showed that the changes in monthly and monthly maximum 1‐ and 5‐day precipitation and discharges during the flood season showed very similar characteristics. They experienced positive (negative) trends mainly in June–July (April, May, and August), and mostly did not experience significant change points. Compared with the period 1969–1990, monthly and monthly maximum 1(5)‐day precipitation and discharges showed increasing (decreasing) trends, mainly in June–July (April–May) in 1991–2011. Overall, the changes in flood risk were mainly influenced by precipitation variability. However, human activity (including urbanization and the construction of reservoirs, soil and water conservation measures, and land use change, among others) have probably affected the flooding process in the study area. The decreases in peak flows during the late 1980s and early 1990s were probably caused by large‐scale soil and water conservation measures. Construction of reservoirs in the past 20 years also played a role in the reduction of peak flows. The results of this study are of great scientific value to better understand the changing flood risk under the changing environment in the Beijiang River basin.
Reliability and validity of procedure‐based assessments in otolaryngology training
Authors: Awad Zaid , Hayden Lindsay , Robson Andrew K. , Muthuswamy Keerthini , Tolley Neil S.
Published: October 2014

Objectives/Hypothesis

To investigate the reliability and construct validity of procedure‐based assessment (PBA) in assessing performance and progress in otolaryngology training.

Study Design

Retrospective database analysis using a national electronic database.

Methods

We analyzed PBAs of otolaryngology trainees in North London from core trainees (CTs) to specialty trainees (STs). The tool contains six multi‐item domains: consent, planning, preparation, exposure/closure, technique, and postoperative care, rated as “satisfactory” or “development required,” in addition to an overall performance rating (pS) of 1 to 4. Individual domain score, overall calculated score (cS), and number of “development‐required” items were calculated for each PBA. Receiver operating characteristic analysis helped determine sensitivity and specificity.

Results

There were 3,152 otolaryngology PBAs from 46 otolaryngology trainees analyzed. PBA reliability was high (Cronbach's α 0.899), and sensitivity approached 99%. cS correlated positively with pS and level in training (rs: +0.681 and +0.324, respectively). ST had higher cS and pS than CT (93% ± 0.6 and 3.2 ± 0.03 vs. 71% ± 3.1 and 2.3 ± 0.08, respectively; P < .001). cS and pS increased from CT1 to ST8 showing construct validity (rs: +0.348 and +0.354, respectively; P < .001). The technical skill domain had the highest utilization (98% of PBAs) and was the best predictor of cS and pS (rs: +0.96 and +0.66, respectively).

Conclusions

PBA is reliable and valid for assessing otolaryngology trainees' performance and progress at all levels. It is highly sensitive in identifying competent trainees. The tool is used in a formative and feedback capacity. The technical domain is the best predictor and should be given close attention.

Level of Evidence

NA Laryngoscope, 125:1328–1335, 2015
Cochlear trajectory in pediatric patients
Authors: Jackson Neal M. , Givens Victoria B. , Carpenter Clelie C. , Allen Laveil M. , Morrell Brooke B. , Hurth Charles , Arriaga Moises A. , Ying Yu‐Lan Mary , Arcement Christopher , McCarter Kevin S. , Jeyakumar Anita
Published: October 2014

Objectives/Hypothesis

As cochlear implantation increases, surgeons are noting possible anatomical differences in pediatric population. Outcome objectives were to study pediatric temporal bone anatomy using high‐resolution temporal bone imaging, and analyze the anatomical differences in group 1 (<12 months) versus group 2 (1–4 years) versus group 3 (5–10 years) versus group 4 (10–18 years).

Study Design

Retrospective chart and radiologic review.

Methods

A retrospective chart and radiologic review of pediatric patients undergoing high‐resolution computer tomography of the temporal bones from April 2001 to February 2013 was conducted. Scans were reviewed to record the transmastoid angle and transcanal angle.

Results

Seven hundred fifty patients were identified. A total of 1,426 ears were reviewed. The age range was 8 days to 21 years. Of the patients, 57.0% (n = 407) were male. The patients were divided into four groups: group 1 (<12 months), group 2 (1–4 years), group 3 (5–10 years), and group 4 (10–18 years). The transmastoid angle was observed to have variability. Significant differences were observed between groups 2 and 3 (P = .0028) and groups 2 and 4 (P = .0432). Analysis on the transcanal angle was performed. Significant differences existed between age groups 1 and 3 (P = .0150), groups 1 and 4 (P = .0038), and groups 2 and 4 (P = .0358).

Conclusions

Considerable variation exists in pediatric temporal bones. The largest difference in the transmastoid angle was seen in children aged 1 to 4 years. The largest variability in the transcanal angle is between the infant (<12 months) and children >4 years of age. These differences are surgically relevant for round window identification and facial nerve safety during cochlear implant surgery in infants.

Level of Evidence

4 Laryngoscope, 125:961–965, 2015
SEC Analysis of Poly(Acrylic Acid) and Poly(Methacrylic Acid)
Authors: Lacík Igor , Stach Marek , Kasák Peter , Semak Vladislav , Uhelská Lucia , Chovancová Anna , Reinhold Günter , Kilz Peter , Delaittre Guillaume , Charleux Bernadette , Chaduc Isabelle , D'Agosto Franck , Lansalot Muriel , Gaborieau Marianne , Castignolles Patrice , Gilbert Robert G. , Szablan Zachary , Barner‐Kowollik Christopher , Hesse Pascal , Buback Michael
Published: October 2014

The accurate characterization of molar‐mass distributions of poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA) by size‐exclusion chromatography (SEC) is addressed. Two methods are employed: direct aqueous‐phase SEC on P(M)AA and THF‐based SEC after esterification of P(M)AA to the associated methyl esters, P(M)MA. P(M)AA calibration standards, P(M)AA samples prepared by pulsed‐laser polymerization (PLP), and PAA samples prepared by reversible addition‐fragmentation chain transfer (RAFT) are characterized in a joint initiative of seven laboratories, with satisfactory agreement achieved between the institutions. Both SEC methods provide reliable results for PMAA. In the case of PAA, close agreement between the two SEC methods is only observed for samples prepared by RAFT polymerization with weight‐average molar mass between 80 000 and 145 000 g mol−1 and for standards with peak molar masses below 20 000 g mol−1. For standards with higher molar masses and for PLP‐prepared PAA, the values from THF‐based SEC are as much as 40% below the molar masses determined by aqueous‐phase SEC. This discrepancy may be due to branching or degradation of branched PAA during methylation. While both SEC methods can be recommended for PMAA, aqueous‐phase SEC should be used for molar‐mass analysis of PAA unless the sample is not branched.

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Visualization of Real‐Time Degradation of pH‐Responsive Polyglycerol Nanogels via Atomic Force Microscopy
Authors: Richter Marcel , Steinhilber Dirk , Haag Rainer , von Klitzing Regine
Published: October 2014

Polyglycerol nanogels (nPG) have a huge impact in biomedical applications as drug deliverer due to their high biocompability. For such nPG nanogels, particle degradation is widely used as drug delivery method. The knowledge of this degradation process is limited up to date. In this communication, a real time visualization of such a degradation process is presented for pH‐responsive nPG nanogels via atomic force microscopy (AFM) under ambient and in liquid conditions. The particle height plays a major role in the degradation process and decays exponentially in the beginning of this process. The particle width increases during the process indicating a “decross‐linking” step of the particles into their starting monomers. Measurements under ambient conditions confirm this assumption and provide further insight in the “decross‐linking” step of the nanogels into individual dendritic particles. The present work gives a detailed insight in the particle degradation process, which is essential for further progress for the development of new drug delivery systems.

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Supramolecular Assembly of Self‐Healing Nanocomposite Hydrogels
Authors: Gerth Marieke , Bohdan Malgorzata , Fokkink Remco , Voets Ilja , van der Gucht Jasper , Sprakel Joris
Published: October 2014

Hierarchical self‐assembly of transient composite hydrogels is demonstrated through a two‐step, orthogonal strategy using nanoparticle tectons interconnected through metal–ligand coordination complexes. The resulting materials are highly tunable with moduli and viscosities spanning many orders of magnitude, and show promising self‐healing properties, while maintaining complete optical transparency.

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A bilayered scaffold based on RGD recombinant spider silk proteins for small diameter tissue engineering
Authors: Zhang Chao‐ying , Zhang Da‐chun , Chen Deng‐long , Li Min
Published: October 2014

A bilayered scaffold was fabricated via electrospinning layer‐by‐layer with the inner layer composed of blend fibers of spider silk protein and gelatin (pNSR16/Gt), then the polyurethane (PU) layer on the outside. The physicochemical and biological performance of scaffold were investigated. The pNSR16/Gt‐PU composite nanofibers with interconnected pores was detected a porosity of 88.7 ± 1.5%; with mechanical properties, including an appropriate permeability of 6.8 ± 0.2 ml min−1 cm−2, breaking strength (24.6 ± 3.6 MPa) and elasticity up to 145 ± 3.8% strain, and burst pressure reached 276 ± 7.1 kPa as well as an accepted suture retention strength (4.9 ± 0.8 N), optimized to mimic the nature artery. The pNSR16/Gt‐PU bilayered scaffold also proved to be capable to support cell growth and proliferation of Sprague‐Dawley rat aortic endothelial cells by 242 ± 10% (7 days vs. control). After all, the intimal surface promotes endothelialization and being highly anti‐thrombogenic, while the mismatch in mechanical properties outside induces intimal hyperplasia, it is desirable to develop a bioactive material with improved mechanical properties for small‐diameter vascular graft. POLYM. COMPOS., 37:523–531, 2016. © 2014 Society of Plastics Engineers
Plasma preparation of carbon black used in conductive coatings
Authors: Yuan J.J. , Hong R.Y. , Wang Y.Q. , Feng W.G.
Published: October 2014

A conductive coatings was prepared using a kind of spherical carbon black (CB) as conductive pigment and polyacrylate (PA) as polymer matrix. The conductive pigment CB nanoparticles were prepared by AC plasma arc method, and then treated with concentrated nitric acid. The pristine and oxidized CB nanoparticles were characterized by scanning and transmission electron microscopy. Afterwards, CB powders were dispersed in PA to produce conductive coatings. The effects of CB content and titanium coupling agent on the volume resistivity were investigated. Furthermore, the rheological and mechanical properties of PA/CB coatings were also investigated. The results showed that the volume resistivity of the PA/CB films was decreased with the increasing of CB content and the electrical percolation threshold was about 2.0 wt%. An interesting result could be observed that the rheological threshold value was close to electrical percolation threshold. In addition, the tensile properties were improved with the addition of CB nanoparticles. POLYM. COMPOS. 37:1078–1084, 2016. © 2014 Society of Plastics Engineers
Effect of interlaminar toughness on the low‐velocity impact damage in composite laminates
Authors: Qu Peng , Sun Xiaochen , Guan Xiaojun , Mu Yidong , Jia Yuxi
Published: October 2014

Based on the continuum damage mechanics (CDM) and the cohesive zone model (CZM), a numerical analysis method for the evaluation of damage in composite laminates under low‐velocity impact is proposed. The intraply damage including matrix crack and fiber fracture is represented by the CDM which takes into account the progressive failure behavior in the ply, using the damage variable to describe the intraply damage state. The delamination is characterized by a special contact law including the CZM which takes into account the normal crack and the tangential slip. The effect of the interlaminar toughness on the impact damage is investigated, which is as yet seldom discussed in detail. The results reveal that as the interlaminar fracture toughness enhances, the delamination area and the dissipated energy caused by delamination decrease. The contribution of normal crack and tangential slip to delamination is evaluated numerically, and the later one is the dominant delamination type during the impact process. Meanwhile, the numerical prediction has a good agreement with the experimental results. The study is helpful for the optimal design and application of composite laminates, especially for the design of interlaminar toughness according to certain requirements. POLYM. COMPOS. 37:1085–1092, 2016. © 2014 Society of Plastics Engineers
The high‐frequency alternating electrical properties of silver powder and its rubber composites
Authors: Li Xuefei , Cao Pei , Yang Chao , Zheng Yuansuo
Published: October 2014

Electromagnetic shielding materials are widely used in alternating electric fields. As a result, the alternating current (AC) conductivity is vital to the electromagnetic shielding effectiveness. In this article, we designed a kind of test method about powder conductive properties and studied AC conductivity of silver powder and the silicon rubber composite, which presented that a sharp peak of impedance would take place in the both systems during the high frequent electric flow. Through the design of the equivalent circuit and the test of the system parameters such as the dielectric constant, this article displayed the impedance model of the silver powder and the silicon rubber composite. The calculated results and the experimental data match very well. POLYM. COMPOS. 37:1122–1127, 2016. © 2014 Society of Plastics Engineers
Preparation, characterization, and antibacterial properties of silver nanoparticles embedded into cellulose aerogels
Authors: Wan Caichao , Jiao Yue , Sun Qingfeng , Li Jian
Published: October 2014

In this article, highly loaded silver (Ag) nanoparticles with mean diameter of about 7.83 nm were synthesized by reducing Ag ions by NaBH4 with strong reducibility, and homogeneously embedded into cellulose aerogels without obvious reunion. The as‐prepared nano‐Ag/cellulose (NAC) aerogels maintained nanoporous and multiscale morphology similar to the pure cellulose aerogels, and showed strong antibacterial activities for both Escherichia coli (Gram negative) and Staphylococcus aureus (Gram positive). Meanwhile, after the incorporation of Ag nanoparticles, NAC aerogels also displayed more superior thermal stability. Thus, the novel NAC aerogels might be expected to be used as various biomedical applications, especially green heat‐resistant high‐performance antibacterial materials. POLYM. COMPOS. 37:1137–1142, 2016. © 2014 Society of Plastics Engineers
Analysis of multiaxial properties of carbon nanotubes/polypropylene and nanocrystalline cellulose/polypropylene composites
Authors: Huang Jun , Rodrigue Denis
Published: October 2014

Using the beam element to simulate single wall carbon nanotube (SWCNT) and nanocrystalline cellulose (NCC), finite element method is adopted to perform multi‐axial numerical tests to compare SWCNT and NCC reinforced polypropylene (PP). As a first step, SWCNT and NCC are assumed to be isotropic and linear elastic materials, while PP is assumed to be linear elastic or elastic–plastic. Using the same reinforcement volume fraction, the elastic and elastic–plastic properties of the nanocomposites are compared under biaxial and triaxial loading conditions. Then, the effect of particle volume fraction and particle size is presented. When NCC and SWCNT have equal particle length and number but different particle diameter, both can produce similar improvement on biaxial mechanical properties. Finally, NCC and SWCNT are compared from an economic point of view to get similar mechanical performance (biaxial properties). The results show that NCC is about 646 times cheaper than SWCNT and is an interesting prospect for future work. POLYM. COMPOS., 37:1180–1189, 2016. © 2014 Society of Plastics Engineers
Methanogen Biomarkers in the Discontinuous Permafrost Zone of Stordalen, Sweden
Authors: Lupascu M. , Wadham J. L. , Hornibrook E. R. C. , Pancost R. D.
Published: October 2014

Permafrost peatlands are both an important source of atmospheric CH4 and a substantial sink for atmospheric CO2. Climate change can affect this balance, with higher temperatures resulting in the conversion of permafrost soils to wetlands and associated accelerated mineralisation and increased CH4 emission. To better understand the impact of such processes on methanogen populations, we investigated the anaerobic decay of soil carbon in a low Arctic, discontinuous permafrost peatland. Cores were collected monthly from sedge and Sphagnum mires in north Sweden during the summer of 2006. We determined CH4 concentrations and production potentials, together with variations in the size of the methanogenic community as indicated by concentrations of archaeal lipid biomarkers (phosphorylated archaeol, archaeol and hydroxyarchaeol). Concentrations of methanogen biomarkers generally were higher at the sedge site, increased with depth for all sites and months, and were usually below the detection limits in shallow (<10 cm) Sphagnum peat. The distribution of biomarkers reflects the strong influence of water table depth on anaerobic conditions and methanogen populations, while differences in biomarker concentrations can be explained by differences in vegetation cover and pH. However, methanogen populations inferred from biomarker data show a decoupling from in‐situ CH4 production over the season and from CH4 production potential, suggesting that other factors such as the availability of labile organic substrates can influence methanogen abundance. Archaeal lipid biomarkers appear to offer a potential new means to investigate permafrost biogeochemical processes but the interpretation of signals remains complex. Copyright © 2014 John Wiley & Sons, Ltd.
Gender‐ and age‐specific risk factors for wheeze from birth through adolescence
Authors: Tse Sze Man , Coull Brent A. , Sordillo Joanne E. , Datta Soma , Gold Diane R.
Published: October 2014

Background and Objective

Cross‐sectional gender differences in wheeze are well documented, but few studies have examined the gender‐specific risk factors for wheeze longitudinally. This study aims to identify gender‐ and age‐specific risk factors for wheeze from birth through adolescence.

Methods

The incidence of wheeze was ascertained every 6 months through age 14 years in a birth cohort consisting of 499 children with a parental history of atopy. Gender‐ and age‐specific risk factors were identified through generalized estimating equations.

Results

A total of 454 (91.0%) and 351 (70.3%) children were followed past age 7 and 13 years, respectively. Maternal asthma was a risk factor for wheeze in girls (OR = 2.05, 95% CI 1.44–2.91, P < 0.0001) and boys (OR = 1.79, 1.29–2.48, P = 0.0004) and had a similar effect on wheeze throughout the ages. Paternal asthma (OR = 1.83, 1.38–2.57, P = 0.0005) and infant bronchiolitis (OR = 2.15, 1.47–3.14, P < 0.0001) were risk factors for boys only, with similar effects throughout the ages.

Conclusion

Using a prospective cohort, we identified gender‐ and age‐specific risk factors for wheeze. The identification of gender‐specific early life risk factors may allow for timely interventions and a more personalized approach to the treatment of asthma. Pediatr Pulmonol. 2015; 50:955–962. © 2014 Wiley Periodicals, Inc.
Levitation of finite‐size electric dipole over epsilon‐near‐zero metamaterial
Authors: Krasikov Sergey , Iorsh Ivan V. , Shalin Alexander , Belov Pavel A.
Published: October 2014

Following the suggestion of Rodriguez‐Fortuno et al. [Phys. Rev. Lett. 112, 033902 (2014)], we study the repulsive force acting on a electric dipole placed over a surface of epsilon‐near‐zero (ENZ) metamaterial. The dependence of the repulsive force value on the dipole size has been studied. We show that the effect of finite size drastically affects the values of the repulsive force as compared to the point‐dipole case. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)
With new channels come new opportunities
Authors: Webb Joe
Published: October 2014

More devices and media lead to more engagement
Estimation of intervention effect using paired interval‐censored data with clumping below lower detection limit
Authors: Xu Ying , Lam K. F. , Cowling Benjamin J. , Bun Cheung Yin
Published: October 2014

Outcome variables that are semicontinuous with clumping at zero are commonly seen in biomedical research. In addition, the outcome measurement is sometimes subject to interval censoring and a lower detection limit (LDL). This gives rise to interval‐censored observations with clumping below the LDL. Level of antibody against influenza virus measured by the hemagglutination inhibition assay is an example. The interval censoring is due to the assay's technical procedure. The clumping below LDL is likely a result of the lack of prior exposure in some individuals such that they either have zero level of antibodies or do not have detectable level of antibodies. Given a pair of such measurements from the same subject at two time points, a binary ‘fold‐increase’ endpoint can be defined according to the ratio of these two measurements, as it often is in vaccine clinical trials. The intervention effect or vaccine immunogenicity can be assessed by comparing the binary endpoint between groups of subjects given different vaccines or placebos. We introduce a two‐part random effects model for modeling the paired interval‐censored data with clumping below the LDL. Based on the estimated model parameters, we propose to use Monte Carlo approximation for estimation of the ‘fold‐increase’ endpoint and the intervention effect. Bootstrapping is used for variance estimation. The performance of the proposed method is demonstrated by simulation. We analyze antibody data from an influenza vaccine trial for illustration. Copyright © 2014 John Wiley & Sons, Ltd.
Engineered Mesenchymal Stem Cells with Enhanced Tropism and Paracrine Secretion of Cytokines and Growth Factors to Treat Traumatic Brain Injury
Authors: Wang Zhe , Wang Yu , Wang Zhiyong , Gutkind J. Silvio , Wang Zhongliang , Wang Fu , Lu Jie , Niu Gang , Teng Gaojun , Chen Xiaoyuan
Published: October 2014

Traumatic brain injury (TBI) is the leading cause of death and disability worldwide. Mesenchymal stem cells (MSCs) are promising for the treatment of various diseases and injuries. Many strategies have been applied to attract MSCs to injury site after systemic infusion. In this study, we evidenced that the CXC chemokine receptor 4 (CXCR4)-SDF1α (stromal cell-derived factor 1α) axis in engineered MSCs serves not only to attract MSC migration to TBI but also to activate Akt kinase signaling pathway in MSCs to promote paracrine secretion of cytokines and growth factors. This leads to enhanced vasculogenesis and neuroprotection at the boundary of TBI for improved blood supply, recovery of axon connectivity, and behavioral ability and results in positive feedback loop to enhance additional MSC tropism to injury. These findings indicate a new aspect of SDF1α in mediating CXCR4 engineered MSCs for brain trauma homing and recovery. This potential mechanism may be applicable to other injuries, where CXCR4-SDF1α interaction is highly associated. Stem Cells  2015;33:456–467
Backbone cyclization of a recombinant cystine‐knot peptide by engineered Sortase A
Authors: Stanger Karen , Maurer Till , Kaluarachchi Harini , Coons Mary , Franke Yvonne , Hannoush Rami N.
Published: October 2014

Cyclotides belong to the family of cyclic cystine‐knot peptides and have shown promise as scaffolds for protein engineering and pharmacological modulation of cellular protein activity. Cyclotides are characterized by a cystine‐knotted topology and a head‐to‐tail cyclic polypeptide backbone. While they are primarily produced in plants, cyclotides have also been obtained by chemical synthesis. However, there is still a need for methods to generate cyclotides in high yields to near homogeneity. Here, we report a biomimetic approach which utilizes an engineered version of the enzyme Sortase A to catalyze amide backbone cyclization of the recombinant cyclotide MCoTI‐II, thereby allowing the efficient production of active homogenous species in high yields. Our results provide proof of concept for using engineered Sortase A to produce cyclic MCoTI‐II and should be generally applicable to generating other cyclic cystine‐knot peptides.