bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photokinetics of two novel photochromic diarylethenes derived from benzothiophene
Authors: Vázquez A. , Nudelman N. Sbarbati 
Published: April 2012

AbstractTwo new unsymmetrically substituted photochromic diarylethenes, namely 3‐[3, 3,4,4,5,5‐hexafluoro‐2‐(2‐methylbenzothien‐3‐yl)cyclopent‐1‐en‐1‐yl]‐2‐methyl‐6‐methoxy‐1‐ benzothiophene and 3‐[3,3,4,4,5,5‐hexafluoro‐2‐(2‐methylbenzothien‐3‐yl)cyclopent‐1‐en‐1‐yl]‐2‐methyl‐6‐methoxy‐7‐nitro‐1‐benzothiophene, were synthesized. Their optical properties and kinetics of cyclization and cycloreversion were determined in four solvents and compared with the symmetrical diarylethene (3,3,4,4,5,5‐hexafluorocyclopent‐1‐en‐1,2‐diyl)bis(2‐methyl‐1‐benzothiophene). While the UV spectra of the three compounds are almost insensitive to solvent changes, the rates of the ring‐opening and ring‐closure reactions exhibit interesting kinetic behavior that differs from other diarylethenes reported in the literature. The cycloreversion for the three compounds follows first‐order kinetics, whereas the cyclization cannot be described by a simple kinetic law. Different approaches were tested, and a complex exponential equation could be derived that fits the experimental data. The unusual presence of two ring‐opened conformational isomers, one of them nonphotochromic, is proposed for the ring‐opened compounds to explain the derived kinetic law and observed solvent effects. These results are of interest in relation to the application of the novel diarylethenes as potential optical materials. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 736–744, 2012
The role of extraesophageal reflux in medically and surgically refractory rhinosinusitis
Authors: Loehrl Todd A. , Samuels Tina L. , Poetker David M. , Toohill Robert J. , Blumin Joel H. , Johnston Nikki 
Published: April 2012

AbstractObjectives/Hypothesis:To clarify the relationship between chronic rhinosinusitis (CRS) and extraesophageal reflux (EER) using state‐of‐the‐art technology. We hypothesized that patients with medically and surgically refractory CRS would have a greater prevalence of EER. We also hypothesized that there would be evidence of gastric refluxate reaching the nasopharynx and paranasal sinuses.Study Design:Case‐control analysis.Methods:Twenty‐two patients with medically and surgically refractory rhinosinusitis were enrolled in the study. Subjects all underwent comprehensive testing for EER including 24‐hour pharyngeal pH probe, aerosolized nasopharyngeal pH testing, and nasopharyngeal tissue biopsy for pepsin analysis. In addition, the last five subjects underwent nasal lavage pepsin analysis. A control group of healthy subjects underwent the same nasal secretion pepsin analysis.Results:Twenty subjects completed the study. The pharyngeal pH probe results were positive in 19/20 (95%), where the DeMeester score was positive in 9/19 (47%). The nasopharyngeal pH probe data were available in 17/20 patients and correlated poorly with the pharyngeal pH probe testing. In all 20 subjects, nasopharyngeal tissue biopsies were negative for pepsin. However, in the five subjects who underwent nasal lavage pepsin analysis, all were pepsin positive while five healthy control nasal lavage pepsin analysis were negative.Conclusions:This study supports an association of EER with medically and surgically refractory CRS. The finding of pepsin in nasal lavages suggests that direct contact of the refluxate with the paranasal sinus mucosa may play a role in the pathophysiology of CRS in this patient population. Finally, evaluation for pepsin in nasal fluid may be a viable method for determining the presence of refluxate in the nose and paranasal sinuses.
Inferior turbinate surgery in children: A survey of practice patterns
Authors: Jiang Zi Yang , Pereira Kevin D. , Friedman Norman R. , Mitchell Ron B. 
Published: April 2012

AbstractObjectives/Hypothesis:A variety of techniques for inferior turbinate reduction have been used in children, but to date practice patterns have not been studied. The purpose of this survey was to study the practice of inferior turbinate surgery among pediatric otolaryngologists.Study Design:Cross‐sectional survey study.Methods:A questionnaire was sent electronically to American Society of Pediatric Otolaryngologists members.Results:A total of 249 questionnaires were sent, and 103 (41%) were completed. Six questionnaires were eliminated due to incompleteness. Seventy‐nine (81%) respondents performed inferior turbinate surgery. The most common reason for not performing the procedure was lack of outcomes data. Coblation was the most common technique used in 51% of respondents. A change in surgical technique in the last 2 to 5 years, most commonly to coblation or microdebridement, was reported by 53% of respondents. Nasal obstruction was the primary indication for turbinate reduction (81%), followed by sleep‐disordered breathing (16%). Respondents reported that 20% of turbinate reductions were sole procedures, and 80% were with other procedures: adenotonsillectomy, septoplasty, and sinus surgery. Fifty‐six (71%) responders were either satisfied or very satisfied with the results of pediatric turbinate surgery. Failure of the procedure, epistaxis, and nasal crusting were commonly reported complications, and 9% reported major complications.Conclusions:A high proportion of pediatric otolaryngologists perform inferior turbinate surgery, most commonly for nasal obstruction. Coblation is the most common technique used, and complications are mostly minor. Physician satisfaction rates are high despite a paucity of outcomes data on the procedure.
Microencapsulation of Alkaline Salt Hydrate Melts for Phase Change Applications by Surface Thiol‐Michael Addition Polymerization
Authors: Platte Daniela , Helbig Uta , Houbertz Ruth , Sextl Gerhard 
Published: April 2012

AbstractThe microencapsulation of alkaline salt hydrates suitable as inorganic phase change materials (PCMs) via surface Michael‐type addition polymerization of thiols and acrylates is reported. The encapsulation performance depending on the resins' acrylate‐to‐thiol ratio and monomer functionality is investigated, and the best encapsulation performance is found for resin compositions with considerable acrylate excess ratios. The step‐growth nature of the reaction can be substantiated via comparative bulk polymerizations. A multistage encapsulation mechanism is proposed in order to explain the different dependencies on the acrylate to thiol ratio observed in PCM encapsulations in comparison to bulk polymerizations.magnified image
Ultrashort TE T1ρ magic angle imaging
Authors: Du Jiang , Statum Sheronda , Znamirowski Richard , Bydder Graeme M. , Chung Christine B. 
Published: April 2012

AbstractAn ultrashort TE T1ρ sequence was used to measure T1ρ of the goat posterior cruciate ligament (n = 1) and human Achilles tendon specimens (n = 6) at a series of angles relative to the B0 field and spin‐lock field strengths to investigate the contribution of dipole–dipole interaction to T1ρ relaxation. Preliminary results showed a significant magic angle effect. T1ρ of the posterior cruciate ligament increased from 6.9 ± 1.3 ms at 0° to 36 ± 5 ms at 55° and then gradually reduced to 12 ± 3 ms at 90°. Mean T1ρ of the Achilles tendon increased from 5.5 ± 2.2 ms at 0° to 40 ± 5 ms at 55°. T1ρ dispersion study showed a significant T1ρ increase from 2.3 ± 0.9 ms to 11 ± 3 ms at 0° as the spin‐lock field strength increased from 150 Hz to 1 kHz, and from 30 ± 3 ms to 42 ± 4 ms at 55° as the spin‐lock field strength increased from 100 to 500 Hz. These results suggest that dipolar interaction is the dominant T1ρ relaxation mechanism in tendons and ligaments. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Oblivious OSPF routing with weight optimization under polyhedral demand uncertainty
Authors: Altin Ayşegül , Fortz B. , Ümit Hakan 
Published: April 2012

AbstractThe desire for configuring well‐managed open shortest path first (OSPF) routes to handle the communication needs in the contemporary business world with larger networks and changing service requirements has opened the way to use traffic engineering tools with the OSPF protocol. Moreover, anticipating possible shifts in expected traffic demands while using network resources efficiently has started to gain more attention. We take these two crucial issues into consideration and study the weight setting problem for OSPF routing problem with polyhedral demands. Our motivation is to optimize the link weight metric such that the minimum cost routing uses shortest paths with equal cost multipath splitting and the routing decisions are robust to possible fluctuations in demands. In addition to a compact mixed integer programming model, we provide an algorithmic approach with two variations to tackle the problem. We present several test results for these two strategies and discuss whether we could make our weight‐managed OSPF comparable to unconstrained routing under polyhedral demand uncertainty. © 2012 Wiley Periodicals, Inc. NETWORKS, 2012
Conceptual design of reinforced concrete structures using topology optimization with elastoplastic material modeling
Authors: Bogomolny Michael , Amir Oded 
Published: April 2012

SUMMARYDesign of reinforced concrete structures is governed by the nonlinear behavior of concrete and by its different strengths in tension and compression. The purpose of this article is to present a computational procedure for optimal conceptual design of reinforced concrete structures on the basis of topology optimization with elastoplastic material modeling. Concrete and steel are both considered as elastoplastic materials, including the appropriate yield criteria and post‐yielding response. The same approach can be applied also for topology optimization of other material compositions where nonlinear response must be considered. Optimized distribution of materials is achieved by introducing interpolation rules for both elastic and plastic material properties. Several numerical examples illustrate the capability and potential of the proposed procedure. Copyright © 2012 John Wiley & Sons, Ltd.
Can Nonexperimental Estimates Replicate Estimates Based on Random Assignment in Evaluations of School Choice? A Within‐Study Comparison
Authors: Bifulco Robert 
Published: April 2012

AbstractThe ability of nonexperimental estimators to match impact estimates derived from random assignment is examined using data from the evaluation of two interdistrict magnet schools. As in previous within‐study comparisons, nonexperimental estimates differ from estimates based on random assignment when nonexperimental estimators are implemented without pretreatment measures of academic performance. With comparison groups consisting of students drawn from the same districts or districts with similar student body characteristics as the districts where treatment group students reside, using pretreatment test scores reduces the bias in nonexperimental methods between 64 and 96 percent. Adding pretreatment test scores does not achieve as much bias reduction when the comparison group consists of students drawn from districts with different student body characteristics than the treatment group students’ districts. The results suggest that using pretreatment outcome measures and comparison groups that are geographically aligned with the treatment group greatly improves the performance of nonexperimental estimators.
Recrystallization behavior of β‐isotactic polypropylene in homogeneous and heterogeneous matrix–fiber composites
Authors: Liu Qi , Li Huihui , Qiu Zhaobin , Yan Shouke 
Published: April 2012

Abstractβ‐isotactic polypropylene (β‐iPP) cylindritic crystals were produced in homogeneous iPP fiber–matrix composites and heterogeneous polyamide (PA)–iPP fiber–matrix composites under different sample preparation conditions. The melt recrystallization behaviors of the β‐iPP crystals obtained in the homogeneous and heterogeneous composites were studied by optical microscopy. The experimental results show that, by heating the sample to 180 °C, the birefringence contributed by the iPP crystals in both α‐ and β‐forms disappears completely. During the cooling process, the β‐iPP crystals in the homogeneous composite appear again, while the iPP in the heterogeneous composite crystallizes in its α‐form. This demonstrates the different origins of the β‐iPP cylindrites in the homogeneous and heterogeneous composites. While the β‐iPP cylindrites in the heterogeneous composite are associated with the sample preparation procedure, the β‐iPP cylindrites in the homogeneous composite are produced by recrystallization of the molten but incompletely relaxed iPP fibers. In situ observation of the melt recrystallization process shows that the molten iPP oriented fibers crystallize first during the cooling process at relatively higher temperature in the α‐form. Abundant randomly dispersed β‐iPP nuclei formed at the surface of the recrystallized iPP fibers, which generate the β‐iPP cylindrites. Copyright © 2012 Society of Chemical Industry
Influence of Average Photon Energy index on solar irradiance characteristics and outdoor performance of photovoltaic modules
Authors: Cornaro Cristina , Andreotti Angelo 
Published: April 2012

ABSTRACTSolar spectral irradiance measurements on a routinely basis are relevant to study the influence of solar spectrum on the photovoltaic (PV) module performance, especially for thin film and third generation PV. Two spectroradiometers from EKO were added to the instrumentation available at the ESTER outdoor station of the University of Rome Tor Vergata. A detailed characterisation of the spectral irradiance at the site was carried on during more than 6 months of monitoring activity measuring spectral solar irradiance in the range 350–1700 nm with a time interval of 10 min on a horizontal plane. A wide variety of spectra were acquired in various weather conditions, and indications about the spectra behaviour on a daily and seasonal basis were obtained. Moreover, information about the effect of the weather conditions on the solar radiation spectral distribution were identified. The Average Photon Energy index was used as an indicator of the spectra characteristics. The same index was also used to evidence the solar spectrum influence on polycrystalline and double junction amorphous silicon PV modules. Copyright © 2012 John Wiley & Sons, Ltd.
Laser processing of Al2O3/a‐SiCx:H stacks: a feasible solution for the rear surface of high‐efficiency p‐type c‐Si solar cells
Authors: Martín I. , Ortega P. , Colina M. , Orpella A. , López G. , Alcubilla R. 
Published: April 2012

AbstractWe explore the potential of laser processing aluminium oxide (Al2O3)/amorphous silicon carbide (a‐SiCx:H) stacks to be used at the rear surface of p‐type crystalline silicon (c‐Si) solar cells. For this stack, excellent quality surface passivation is measured with effective surface recombination velocities as low as 2 cm/s. By means of an infrared laser, the dielectric film is locally opened. Simultaneously, part of the aluminium in the Al2O3 film is introduced into the c‐Si, creating p+ regions that allow ohmic contacts with low‐surface recombination velocities. At optimum pitch, high‐efficiency solar cells are achievable for substrates of 0.5–2.5 Ω cm. Copyright © 2012 John Wiley & Sons, Ltd.
Performance analysis of a reflective 3D crossed compound parabolic concentrating photovoltaic system for building façade integration
Authors: Mammo Eliyas Debebe , Sellami Nazmi , Mallick Tapas Kumar 
Published: April 2012

ABSTRACTA reflective 3D crossed compound parabolic‐based photovoltaic module (3D CCPC PV) was designed and its electrical and optical performance was analyzed for building integrated photovoltaic applications. A maximum power concentration of 3.0× was achieved compared to similar type of non‐concentrating module. The reduction of the concentration factor from the geometrical concentration of 3.61× for the designed 3D CCPC were due to manufacturing errors, mismatch losses, series resistance losses, and thermal loses. The experimental output was validated by developing a MATLAB simulation code for its electrical performance. Good agreements were observed between experimental and electrical simulation with maximum electrical conversion efficiency of the concentrating system of 14%. The experimental characterization of the optical efficiency was found to show a deviation of 19.4% from the 3D ray tracing simulation efficiency of 94.6% for direct incidence. This deviation is mainly due to the fact that 3D ray tracing simulation does not take the non‐uniform illumination distribution into account. Copyright © 2012 John Wiley & Sons, Ltd.
Multidisciplinary care of patients with Parkinson's disease
Authors: Skelly Rob , Lindop Fiona , Johnson Claire 
Published: April 2012

AbstractThere is increasing evidence that the effective care of patients with Parkinson's disease should involve a multidisciplinary team of health professionals, including the neurologist or geriatrician, Parkinson's disease nurse specialist, physiotherapist, occupational therapist, speech and language therapist, dietitian, clinical psychologist and social worker, among others. Here, the authors review the evidence for the efficacy of multi‐disciplinary working and describe their own model of care in Derby.
High‐performance amorphous donor–acceptor conjugated polymers containing x‐shaped anthracene‐based monomer and 2,5‐bis(2‐octyldodecyl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione for organic thin‐film transistors
Authors: Lee Joo Bin , Kim Kyung Hwan , Hong Chang Seop , Choi Dong Hoon 
Published: April 2012

AbstractNew diketopyrrolopyrrole (DPP)‐containing amorphous conjugated polymers, such as poly(3‐(5‐((9,10‐bis((4‐hexylphenyl)ethynyl)‐6‐(prop‐1‐ynyl)anthracen‐2‐yl)ethynyl) thiophen‐2‐yl)‐5‐(2‐hexyldecyl)‐2‐(2‐octyldodecyl)‐6‐(thiophen‐2‐yl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione) (4), and poly(3‐(5‐((2,6‐bis((4‐hexylphenyl)ethynyl)‐10‐(prop‐1‐ynyl)anthracen‐9‐yl)ethynyl)thiophen‐2‐yl)‐2,5‐bis(2‐octyldodecyl)‐6‐(thio phen‐2‐yl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione) (7), were successfully synthesized via Sonogashira coupling reactions under microwave conditions. Copolymer 7, incorporating a DPP moiety at the 9,10‐position of the anthracene ring through a triple bond, showed a much lower bandgap energy (Eg = 1.81 eV) than copolymer 4 (Eg = 2.13 eV). Tuning of the molecular frontier orbital energies was achieved by only changing the anchoring position of dithiophenyl‐DPP from the 2,6‐ to the 9,10‐position in the anthracene ring. Because of the donor–acceptor (D–A) interaction and the two‐dimensional planar structure of the X‐shaped donor monomer, the resulting polymers showed good interchain π−π stacking in the thin‐film state, despite being amorphous polymers. When the newly synthesized polymer 7 was used as a semiconductor material in an organic thin‐film transistor, the best mobility of up to 0.12 cm2 V−1 s−1 (Ion/off = ∼ 4.4 × 106) was observed, which is one of the highest values recorded for amorphous polymer films reported to date. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis of NMP/RAFT inifers and preparation of block copolymers
Authors: St. Thomas Claude , Maldonado‐Textle Hortensia , Rockenbauer Antal , Korecz Laszlo , Nagy Nora , Guerrero‐Santos Ramiro 
Published: April 2012

AbstractTwo different initiator/transfer agents (inifers) containing an alkoxyamine and a dithiobenzoate were synthetized and used to trigger out either reversible addition‐fragmentation chain transfer (RAFT) polymerization or nitroxide‐mediated polymerization (NMP). α‐Dithiobenzoate‐ω‐alkoxyamine‐difunctional polymers were produced in both cases which were subsequently used as precursors in the formation of block copolymers. This synthetic approach was applied to N‐isopropylacrylamide (NIPAM) or polyethylene oxide methacrylate (EOMA) to form α,ω‐heterodifunctional homopolymers via RAFT at 60°C which were chain extended with styrene by activating the alkoxyamine moiety at 120°C. Under such temperature conditions, it is proposed that a tandem NMP/RAFT polymerization is initiated producing a simultaneous growth of polystyrene blocks at both chain‐ends. Self‐assembled nanostructures of these amphiphilic block copolymers were evidenced by scanning electron microscopy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Synthesis and properties of monocleavable amphiphilic comblike copolymers with alternating PEG and PCL grafts
Authors: Li Shixian , Ye Chunnuan , Zhao Guangdong , Zhang Meijing , Zhao Youliang 
Published: April 2012

AbstractSymmetric reduction‐responsive amphiphilic comblike copolymers mid‐disulfide‐functionalized comblike copolymers with alternating copolymer comprised of styrenic unit and N‐(2‐hydroxyethyl) maleimide (HEMI) unit (poly(St‐alt‐HEMI)) backbones and alternating PEG and PCL side chains (S‐CP(PEG‐alt‐PCL)) with poly(St‐alt‐HEMI) backbones and alternating poly(ε‐caprolactone) (PCL) and poly(ethylene glycol) (PEG) side chains were synthesized and used as nanocarriers for in vitro release of doxorubicin. The target copolymers with predetermined molecular weight and narrow molecular weight distribution (Mw/Mn = 1.15–1.20) were synthesized by reversible addition‐fragmentation chain transfer (RAFT) copolymerization of vinylbenzyl‐terminated PEG and N‐(2‐hydroxyethyl) maleimide mediated by a disulfide‐functionalized RAFT agent S‐CPDB, and followed by ring‐opening polymerization of ε‐caprolactone. When compared with linear block copolymer comprised of poly(ethylene glycol) (PEG) and poly(ϵ‐caprolactone) (PCL) segments (PEG‐b‐PCL) copolymers, comblike copolymers with similar PCL contents usually exhibited decreased crystallization temperature, melting temperature, and degree of crystallinity, indicating the significant influence of copolymer architecture on physicochemical properties. Dynamic light scattering measurements revealed that comblike copolymers were liable to self‐assemble into aggregates involving vesicles and micelles with average diameter in the range of 56–226 nm and particle size distribution ranging between 0.07 and 0.20. In contrast to linear copolymer aggregates, comblike copolymer aggregates with similar compositions were of improved storage stability and enhanced drug‐loading efficiency. In vitro drug release confirmed the disulfide‐linked comblike copolymer aggregates could rapidly release the encapsulated drug when triggered by 10 mM DL‐dithiothreitol. These reduction‐sensitive, biocompatible, and biodegradable aggregates have a potential as controlled delivery vehicles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012