bluuebunny/crossref_metadata_2025_split huggingface dataset:
Donor–acceptor diethynylsilane oligomers: A second‐order nonlinear optical material
Authors: Machado Ana E. De A. , Souza Leonardo A. De , Dos Santos Hélio F. , Almeida Wagner B. De 
Published: August 2011

AbstractThe interest in the study of oligomers has been motivated mainly because of their solubility in common solvents and also their capacity to be crystallized, which allowed for chemical processing leading to important applications in the area of material sciences. In this work, we carried out an investigation of polydiethynylsilane (PDES) decamers substituted with electron donor (D) and acceptor (A) groups, which is certainly of relevance, once PDES itself is known to display large third‐order optical susceptibility. Therefore, density functional theory calculations of static first hyperpolarizability (β) were performed using various functionals with the 6‐31G(d) basis set along with correlated MP2 calculation used as reference for comparison. The influence of A and D substituents on the magnitude of β was investigated by matching the acceptor (dicyanovinyl, nitrobenzene) and donor (propyl, propoxy, and phenylamine) groups attached at both ends of the oligomer. The largest β value was predicted for the derivative having the phenylamine and dicyanovinyl groups, which is around 30 times the relative value for the nonsubstituted decamer, what is a very impressive enhancement reported for the first time in the literature, strongly suggesting that disubstituted diethynylsilane decamers are potential building blocks for molecular‐based materials with second‐order nonlinear responses. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1410–1419, 2011
Modification of Polydimethylsiloxane Thin Films in H2 Radio‐frequency Plasma Investigated by Infrared Reflection Absorption Spectroscopy
Authors: Danilov Vladimir , Wagner Hans‐Erich , Meichsner Jürgen 
Published: August 2011

AbstractThe plasma modification of polydimethylsiloxane (PDMS) thin films was studied by means of Fourier Transform Infrared Reflection Absorption Spectroscopy (FT‐IRRAS). The spin‐coated PDMS films (10–175 nm) were prepared on aluminium coated glass substrates, and their thickness was measured by spectroscopic ellipsometry. The direct hydrogen RF plasma interaction with PDMS is compared with the hydrogen plasma radiation, only. The evolution of the thin film IR absorption spectrum was monitored, and the changes of PDMS characteristic absorption bands as well as the formation of new bands are discussed. In particular, the appearance of a new band at 1 230 cm−1 was observed, and it was identified as LO phonon band of SiOx. magnified image
Ion and Vacuum Ultraviolet Photon Beam Effects in 193 nm Photoresist Surface Roughening: The Role of the Adamantyl Pendant Group
Authors: Chung Ting‐Ying , Graves David B. , Weilnboeck Florian , Bruce Robert L. , Oehrlein Gottlieb S. , Li Mingqi , Hudson Eric A. 
Published: August 2011

AbstractPrevious studies have identified a synergistic effect of ion bombardment, vacuum ultraviolet (VUV) radiation, and moderate substrate heating in 193 nm photoresist (PR) surface roughening. The degree of surface roughness is comparable to that obtained from typical plasma etch processes. Ion bombardment results in a carbon‐rich surface layer with a thickness of a few nanometers, and VUV radiation causes bulk modification to a depth of about 100 nm. The probable difference in mechanical properties between the carbon‐rich surface layer and the softened underlayer is proposed to be the main cause of PR surface roughening. In the same vacuum beam apparatus, we further characterize the roughening of associated homopolymers: poly‐(2‐methyl‐2‐adamantyl methacrylate) (p‐MAMA) and poly‐(R‐functionalized adamantyl methacrylate) (p‐RAMA). MAMA is the leaving group, and RAMA is the polar group in 193 nm PR, respectively. Monitored by ex situ transmission FTIR and in situ mass spectrometry, p‐MAMA undergoes temperature‐dependent bulk degradation during VUV exposure while p‐RAMA is relatively insensitive to VUV. We identify the adamantyl leaving group as one of the main photolysis products from p‐MAMA. Higher substrate temperatures increase the vapor pressure and facilitate desorption of the detached adamantyl leaving group. The adamantane loss/detachment shows strong correlation to PR surface roughening. A bi‐layer wrinkling mechanism is proposed to qualitatively explain the observed surface roughening. The present results demonstrate that PR leaving group content and structure can couple to plasma etching processes and strongly alter post‐etch surface morphology. magnified image
Parent‐reported ISAAC written questionnaire may underestimate the prevalence of asthma in children aged 10–12 years
Authors: Kim Myoung Hee , Kwon Ji‐Won , Kim Hyo Bin , Song Younghwa , Yu Jinho , Kim Woo‐Kyung , Kim Byeong‐Ju , Lee So Yeon , Kim Kyoung‐Won , Ji Hye‐Mi , Kim Kyu‐Earn , Shin Yee‐Jin , Kim Ho , Hong Soo‐Jong 
Published: August 2011

AbstractObjectivesThe aim of the present study was to compare the validity of the International Study of Asthma and Allergies in Childhood (ISAAC) written (WQ) and audiovisual questionnaires (AVQ 3.0) in two age‐groups (10–12 and 13–15 years, respectively).MethodsThe 13–15 year olds performed the self‐completed the WQ and AVQ on the same day. The 10–12 year olds performed the self‐completed the AVQ and the parent‐completed WQ was completed by their parents. The methacholine challenge test was conducted in 10–12 year olds from one elementary school.ResultsIn 10–12 year olds, the AVQ detected a generally higher prevalence of asthma symptoms than WQ. In 13–15 year olds, this was reversed. In 10–12 year olds, poor agreement was found between the parent‐completed WQ and the self‐reported AVQ. In 13–15 year olds, moderate agreement was found between the self‐reported WQ and AVQ. Low sensitivity was found, in predicting bronchial hyper‐responsiveness (BHR) for all questions of both WQ and AVQ in 10–12 year olds. However, the AVQ had slightly higher sensitivity than WQ, with the exception of wheeze ever, although it was not statistically significant.ConclusionThe ISAAC AVQ may be another effective instrument for assessing the prevalence of asthma symptoms in children aged 10–12 years, whereas the parent‐reported‐WQ may underestimate the prevalence of asthma symptoms in this age‐group. Pediatr Pulmonol. 2012; 47:36–43. © 2010 Wiley Periodicals, Inc.
A comparison of fluoroscopic airway screening with flexible bronchoscopy for diagnosing tracheomalacia
Authors: Sanchez M.O. , Greer M.C. , Masters I.B. , Chang A.B. 
Published: August 2011

AbstractBackgroundFlexible bronchoscopy (FB) is the gold standard method of diagnosing tracheomalacia but it is not always feasible in settings with limited resources. Fluoroscopy is sometimes performed as an alternative diagnostic tool but there are no prospective studies that have evaluated the diagnostic accuracy of airway fluoroscopy for tracheomalacia using a‐priori definitions. We determined the sensitivity, specificity, and likelihood predictive ratio of airway fluoroscopy compared with FB in children suspected of having an airway abnormality.MethodsAirway fluoroscopic examination was undertaken within 2‐weeks of a FB in children aged <18‐years and reported by a pediatric radiologist blinded to FB data. Fluoroscopic and FB methods and diagnostic criteria were standardized and defined a‐priori. Tracheomalacia diagnosed by FB were independently scored (mild, moderate, severe) by 2 pulmonologists in a blinded manner.ResultsIn 22 children (median age 33 months, range 1–187) evaluated for airway abnormality, tracheomalacia was found in 21 children at bronchoscopy. Of these, fluoroscopy detected tracheomalacia in five children. Airway fluoroscopy was poorly sensitive (23.8%) but highly specific (100%), positive likelihood ratio was 8.6. However, in moderate‐severe tracheomalacia, the sensitivity improved to 57.1% but the specificity reduced (93.3%). The agreement between bronchoscopists for tracheomalacia severity was excellent, weighted kappa 0.74 (95% CI 0.77, 0.98).ConclusionAirway fluoroscopy cannot replace FB which remains the tool for definitively diagnosing airway malacia. However, in absence of other modalities for diagnosis fluoroscopy should be considered in the setting of persistent respiratory symptoms compatible with the clinical picture of tracheomalacia. Pediatr Pulmonol. 2012; 47:63–67. © 2010 Wiley Periodicals, Inc.
Defining pulmonary exacerbation in children with non‐cystic fibrosis bronchiectasis
Authors: Kapur Nitin , Masters Ian B. , Morris Peter S. , Galligan John , Ware Robert , Chang Anne B. 
Published: August 2011

AbstractRationaleExacerbations in non‐cystic fibrosis (CF) bronchiectasis are associated with worsening lung functions and quality of life. A standardized definition of exacerbation could improve clinical care and research.ObjectiveTo formulate a clinically useful definition of pulmonary exacerbation for pediatric non‐CF bronchiectasis.MethodsA cohort of 69 children with non‐CF bronchiectasis was prospectively followed for 900 child‐months. The changes in clinical, systemic, and lung function parameters from 81 exacerbations were statistically evaluated using conditional logistic regression, receiver operating characteristic, sensitivity, specificity, and positive (PPV) and negative predictive values (NPV) to formulate a definition of a pulmonary exacerbation. Formation of major and minor criteria was statistically based and models were developed.Measurements and Main ResultsWet cough and cough severity (score ≥2) over 72‐hr were the best predictors of an exacerbation with area under the curve (AUC) of 0.85 (95% CI 0.79–0.92) and 0.84 (95% CI 0.77–0.91), respectively. Sputum color, chest pain, dyspnea, hemoptysis, and chest signs were significant though minor criteria. Inclusion of serum C‐reactive protein, amyloid‐A, and IL6 to the definition improved its specificity and PPV. Our final combined model consisted of one major with one investigatory criterion (PPV 91%, NPV 72%); two major criteria (PPV 79%, NPV 91%); or one major and two minor criteria (PPV 79%, NPV 94%).ConclusionsPulmonary exacerbation in children with non‐CF bronchiectasis can be validly predicted using a standardized assessment of clinical features, with additional systemic markers improving predictive values. This definition potentially facilitates earlier detection (leading to appropriate management) of exacerbations. Pediatr Pulmonol. 2012; 47:68–75. © 2010 Wiley Periodicals, Inc.
Initial Pseudomonas aeruginosa treatment failure is associated with exacerbations in cystic fibrosis
Authors: Mayer‐Hamblett Nicole , Kronmal Richard A. , Gibson Ronald L. , Rosenfeld Margaret , Retsch‐Bogart George , Treggiari Miriam M. , Burns Jane L. , Khan Umer , Ramsey Bonnie W. ,   for the EPIC Investigators
Published: August 2011

AbstractRationaleThe risk of pulmonary exacerbation following Pseudomonas aeruginosa (Pa) acquisition in children with cystic fibrosis (CF) is unknown.ObjectivesTo determine if failure of antibiotic therapy to eradicate Pa and frequency of Pa recurrence are associated with increased exacerbation risk.MethodsThe cohort included 282 children with CF who participated in the EPIC trial ages 1–12 with newly acquired Pa, defined as either a first lifetime Pa positive respiratory culture or positive after two years of negative cultures (past isolation of Pa but >2 years prior to the trial). All received antibiotics to promote initial eradication followed by 15 months of intermittent maintenance antibiotics. Quarterly cultures were used to define initial eradication success and subsequent number of Pa recurrences. A standardized symptom‐based definition of exacerbation was utilized. Cox proportional hazards models were used to estimate exacerbation risk.ResultsFailure to initially eradicate Pa was associated with exacerbation risk (hazard ratio [HR]: 2.49, 95% confidence interval [CI] 1.26, 4.93). In 245/282 with successful initial eradication during the trial, past isolation of Pa >2 years before the trial was the most significant predictor of exacerbation (HR 1.62, 95% CI 1.12, 2.35). In 37/282 who failed initial eradication, persistent Pa during the maintenance phase (1 or more Pa recurrences after failure to initially eradicate) added even greater exacerbation risk (HR 4.13, 95% CI 1.28, 13.32).ConclusionsChildren with CF who fail to eradicate after initial antibiotic treatment are at higher risk of subsequent exacerbation, suggesting clinical benefit to successful early eradication of Pa infection. Pediatr Pulmonol. 2012; 47:125–134. © 2011 Wiley Periodicals, Inc.
Variable human phenotype associated with novel deletions of the PHOX2B gene
Authors: Jennings Lawrence J. , Yu Min , Rand Casey M. , Kravis Nicole , Berry‐Kravis Elizabeth M. , Patwari Pallavi P. , Weese‐Mayer Debra E. 
Published: August 2011

AbstractBackgroundClinical testing for PHOX2B mutations is widely used for patients with any symptoms suggestive of hypoventilation (with/without anatomic/physiologic autonomic dysregulation), though not necessarily with the congenital central hypoventilation syndrome (CCHS) phenotype. Consequently, a multitude of referrals for clinical PHOX2B testing (fragment analysis of the 20 polyalanine repeat region and/or sequencing of entire coding region) have no identifiable mutation. Whole gene deletions/duplications have recently been identified as a common disease‐causing mechanism, but have not been reported in a clinical population referred for PHOX2B testing. The objective of this study was to determine if PHOX2B exon or whole gene deletion/duplication would be identified in a subset of patients referred for PHOX2B testing.HypothesisWe hypothesized that PHOX2B exon or whole gene deletion or duplication would be identified in a subset of cases who were referred for genetic testing but not found to have a PHOX2B mutation with currently available clinical PHOX2B testing.MethodsGenomic DNA samples from patients that tested negative for PHOX2B mutations using fragment analysis and/or sequencing, and control samples, were screened for PHOX2B exon deletions/duplications by multiplex ligation‐dependent probe amplification with confirmation by array comparative genomic hybridization.ResultsDeletions of/in PHOX2B were identified in 4/250 patients and 0/261 controls. The deletions ranged from 6,216 base pairs (involving only PHOX2B exon 3) to 2.6 megabases (involving all of PHOX2B and 12 other genes). The case with PHOX2B partial exon 3 deletion had a CCHS‐compatible phenotype (hypoventilation, Hirschsprung disease). Phenotypes for the other three cases, all PHOX2B whole‐gene deletions, were varied including: (1) apparent life threatening event, (2) full CCHS necessitating artificial ventilation with ganglioneuroblastoma, and (3) hypoventilation during sleep. Family studies of two of the four probands showed these deletions to be maternally inherited; the mothers also had phenotypic findings of autonomic dysfunction.ConclusionsPHOX2B exon or whole gene deletion should be considered as another mechanism of disease which may include CCHS, Hirschsprung disease, and/or tumors of neural crest origin, although the genotype–phenotype relationship requires further clarification. Pediatr Pulmonol. 2012; 47:153–161. © 2011 Wiley Periodicals, Inc.
Structural classification and properties of ketoacyl synthases
Authors: Chen Yingfei , Kelly Erin E. , Masluk Ryan P. , Nelson Charles L. , Cantu David C. , Reilly Peter J. 
Published: August 2011

AbstractKetoacyl synthases (KSs) catalyze condensing reactions combining acyl‐CoA or acyl‐acyl carrier protein (acyl‐ACP) with malonyl‐CoA to form 3‐ketoacyl‐CoA or with malonyl‐ACP to form 3‐ketoacyl‐ACP. In each case, the resulting acyl chain is two carbon atoms longer than before, and CO2and either CoA or ACP are formed. KSs also join other activated molecules in the polyketide synthesis cycle. Our classification of KSs by their primary and tertiary structures instead of by their substrates and the reactions that they catalyze enhances insights into this enzyme group. KSs fall into five families separated by their characteristic primary structures, each having members with the same catalytic residues, mechanisms, and tertiary structures. KS1 members, overwhelmingly named 3‐ketoacyl‐ACP synthase III or its variants, are produced predominantly by bacteria. Members of KS2 are mainly produced by plants, and they are usually long‐chain fatty acid elongases/condensing enzymes and 3‐ketoacyl‐CoA synthases. KS3, a very large family, is composed of bacterial and eukaryotic 3‐ketoacyl‐ACP synthases I and II, often found in multidomain fatty acid and polyketide synthases. Most of the chalcone synthases, stilbene synthases, and naringenin‐chalcone synthases in KS4 are from eukaryota. KS5 members are all from eukaryota, most are produced by animals, and they are mainly fatty acid elongases. All families except KS3 are split into subfamilies whose members have statistically significant differences in their primary structures. KS1 through KS4 appear to be part of the same clan. KS sequences, tertiary structures, and family classifications are available on the continuously updated ThYme (Thioester‐active enzYme) database.
Fabrication of adherent porous diamond films on sintered WC‐13 wt.%Co substrates by bias enhanced hot filament chemical vapour deposition
Authors: Wei Q. , Ashfold M. N. R. , Yu Z. M. , Ma L. 
Published: August 2011

AbstractPorous diamond (PD) films have been grown on sintered WC‐13 wt.%Co substrates by bias enhanced hot filament (HF) chemical vapour deposition (CVD) methods and characterized by scanning electron microscopy (SEM), laser Raman spectroscopy and X‐ray diffraction (XRD). The PD films show excellent adhesion under Rockwell indentation testing. Factors encouraging the growth of diamond film with high porosity are discussed. magnified image
Effect of argon addition on the growth of thick single crystal diamond by high‐power plasma CVD
Authors: Tallaire Alexandre , Rond Catherine , Bénédic Fabien , Brinza Ovidiu , Achard Jocelyn , Silva François , Gicquel Alix 
Published: August 2011

AbstractDiamond films were synthesized with up to 50% argon in the gas phase using high power plasma‐assisted chemical vapour deposition (PACVD). This resulted in a strong increase of the deposition rates. Polycrystalline diamond (PCD) films grown with Ar have shown a higher incorporation of sp2 phases but with no dramatic change in crystal morphologies. Thick single crystal diamond films did not show any obvious change in crystal quality though. By using optical emission spectroscopy (OES) and plasma simulation, it was found that the gas temperature is increased by the addition of argon by at least 500 K. This in turn promotes dissociation of H2 into H‐atom as would be obtained from an increase of the plasma power density. High‐power PACVD with argon addition is thus an efficient technique for the fast growth of thick single crystal films without the cost and additional problems related to an increase of the injected microwave power.
On the quantum efficiency of InGaN light emitting diodes: Effects of active layer design, electron cooler, and electron blocking layer
Authors: Li X. , Zhang F. , Okur S. , Avrutin V. , Liu S. J. , Özgür Ü. , Morkoç H. , Hong S. M. , Yen S. H. , Hsu T. S. , Matulionis A. 
Published: August 2011

AbstractEfficiency and efficiency retention in InGaN LEDs has recently received considerable attention. In this realm, we investigated internal quantum efficiency (IQE) and relative external quantum efficiency (EQE) of c‐plane InGaN LEDs designed for emission at ∼420 nm from the active region which contains multiple quantum wells (MQWs) of different barrier height (either In0.01Ga0.99N or In0.06Ga0.94N barriers) and thickness (3 and 12 nm) as well as a 9‐nm double heterostructure (DH). Pulsed electroluminescence (EL) and laser excitation power‐dependent measurements indicated that both the relative EQE and the IQE were enhanced due to the incorporated two‐layer InGaN stair‐case electron injector (SEI) with indium mole fraction steps of 4 and 8% as compared to the conventional AlGaN electron blocking layer (EBL). Furthermore, the lowered In0.06Ga0.94N interwell barriers (LB) instead of the traditional In0.01Ga0.99N barriers improved the EQE and the IQE of MQW LEDs. Specifically, the MQW LEDs with the 6‐period 2‐nm In0.2Ga0.8N quantum well and 3‐nm In0.06Ga0.94N barrier structure showed 6% higher IQE at an injected carrier density of 6 × 1018 cm−3 and 35% higher EQE as compared to that of the same structure with a higher In0.01Ga0.99N barrier. The DH LEDs showed 30% higher EQEs compared to MQW LEDs, albeit at a relatively higher injection current density of 150 A/cm2. The relatively low EQE in the DH LEDs at low injection levels is attributed to spatial separation of electrons and holes due to confinement in the interfacial triangular well and thus the associated decrease in radiative efficiency and possible increase in nonradiative recombination due to degradation of material quality with increasing InGaN layer thickness.
Map‐aided localization in sparse global positioning system environments using vision and particle filtering
Authors: Miller Isaac , Campbell Mark , Huttenlocher Dan 
Published: August 2011

AbstractA map‐aided localization approach using vision, inertial sensors when available, and a particle filter is proposed and empirically evaluated. The approach, termed PosteriorPose, uses a Bayesian particle filter to augment global positioning system (GPS) and inertial navigation solutions with vision‐based measurements of nearby lanes and stop lines referenced against a known map of environmental features. These map‐relative measurements are shown to improve the quality of the navigation solution when GPS is available, and they are shown to keep the navigation solution converged in extended GPS blackouts. Measurements are incorporated with careful hypothesis testing and error modeling to account for non‐Gaussian and multimodal errors committed by GPS and vision‐based detection algorithms. Using a set of data collected with Cornell's autonomous car, including a measure of truth via a high‐precision differential corrections service, an experimental investigation of important design elements of the PosteriorPose estimator is conducted. The algorithm is shown to statistically outperform a tightly coupled GPS/inertial navigation solution both in full GPS coverage and in extended GPS blackouts. Statistical performance is also studied as a function of road type, filter likelihood models, bias models, and filter integrity tests. © 2011 Wiley Periodicals, Inc.