bluuebunny/crossref_metadata_2025 huggingface dataset:
Do abstracts in otolaryngology journals report study findings accurately?
Authors: McCoul Edward D. , Vengerovich Gennadiy , Burstein David H. , Rosenfeld Richard M.
Published: January 2010

Objectives

Although published abstracts have the advantage of being prominent and concise, their quality in the otolaryngology literature has not been studied. We sought to understand the limitations of relying on abstracts as the sole source of information about published research. In addition, we sought to identify specific opportunities for improving the quality of published articles and their associated abstracts.

Methods

Studies of original research published in four major otolaryngology journals from January 2008 to June 2008 were included. Each study article and abstract was reviewed separately for 12 domains relating to study design, results, and conclusions. Good inter‐rater reliability was established as part of the validation process.

Results

Four hundred eighteen articles were identified for study, which included 75 percent clinical research and 25 percent basic science. The most common omissions in the abstract when compared with the complete article were study limitations (91% left out of abstract), geographic location (79%), confidence intervals (75%), dropouts or losses (62%), and harms and adverse events (44%). Conversely, the abstract often included information about research design (99%), sample size (92%), source of the data (81%), and quantitative results (67%). These results did not differ significantly with regard to article type, journal, or level of evidence.

Conclusions

Readers of otolaryngology journals may form biased or inappropriate conclusions if they read only the abstract of a study, particularly with regard to study limitations, adverse events, and subject dropouts or losses. These results highlight the perils of using the abstract as a sole source of information.
Propofol‐induced sleep: Polysomnographic evaluation of patients with obstructive sleep apnea and controls
Authors: Rabelo Fábio A.W. , Braga Adriano , Küpper Daniel S. , De Oliveira José A.A. , Lopes Fernando M. , de Lima Mattos Pedro Luiz Vaz , Barreto Shirley G. , Sander Heidi H. , Fernandes Regina M.F. , Valera Fabiana C.P.
Published: January 2010

Objective

The localization of upper airway obstruction in patients with obstructive sleep apnea (OSA) may optimize treatment. Nasoendoscopy during propofol sedation allows such an evaluation, but the effect of this drug on respiratory patterns and muscle relaxation is unknown. The objective of the present study was to determine through polysomnography whether propofol would change sleep parameters.

Study Design

Prospective study of subjects submitted to polysomnography under sedation with propofol.

Setting

Tertiary referral center.

Subjects and Methods

Fifteen non‐obese subjects (4 controls/11 OSA patients) were submitted to two diurnal polysomnograms (90‐120 minutes of sleep), with and without the use of propofol. The parameters presence of snoring, apnea‐hypopnea index (AHI), oxygen desaturation, and sleep architecture were compared.

Results

The use of propofol did not induce snoring in the control subjects, whereas 100 percent of the OSA patients snored. AHI and mean oxygen saturation (SaO2) did not differ significantly between examinations with and without sedation. However, minimum SaO2 differed significantly (P < 0.05) with sedation, being lower during propofol sedation. Propofol also significantly changed the sleep architecture, with a significant increase in N3 sleep (P < 0.005) and total abolishment of rapid eye movement sleep (P < 0.0005) during propofol sedation.

Conclusions

These preliminary results allow us to infer that sedation with propofol changes sleep architecture but permits respiratory evaluation, because the main respiratory parameters evaluated in OSA are maintained. These preliminary results support the view that nasoendoscopy under propofol sedation is a promising examination for management of this disease.
A randomized, prospective, controlled study of forearm donor site healing when using a vacuum dressing
Authors: Chio Eugene G. , Agrawal Amit
Published: January 2010

Objective

1) Compare skin graft healing of the radial forearm free flap (RFFF) donor site when using a negative pressure dressing (NPD) versus a static pressure dressing (SPD). 2) Examine the association of graft size and medical comorbidities with healing of RFFF donor site.

Study Design

Randomized, controlled trial.

Setting

Tertiary care hospital.

Subjects and Methods

After the study was approved, consenting adults undergoing RFFF for head and neck reconstructions were randomized into two arms: SPD and NPD groups. Fifty‐four patients were enrolled from March 2007 to August 2009. Pre‐ and postoperative data were collected, including medical comorbidities, graft size, and area of graft failure/tendon exposure. Data were collected at two postoperative time points.

Results

The overall wound complication rate was 38 percent (19/50). Wound complications at the first postoperative visit (44.4% [12/27] SPD and 30.4% [7/23] NPD) were not significantly different between groups (P = 0.816). Similarly, wound complications at the second visit (68.8% [11/16] SPD and 80% [12/15] NPD) were not significantly different (P = 0.55). Percentage of area of graft failure between the groups also showed no difference (4.5% SPD vs 7.2% NPD, P = 0.361). The association of graft size with wound complications was analyzed by dividing the data set into three groups (<50 cm2, 51‐100 cm2, and >100 cm2). This difference was not found to be significant (P = 0.428). Finally, when evaluating comorbidities, 50 percent (8/16) of subjects with comorbidities experienced complications compared with 32.4 percent (11/34) without comorbidities, also not reaching significance (P = 0.203).

Conclusions

Although an attractive option for wound care, the NPD does not appear to offer a significant improvement over an SPD in healing of the RFFF donor site.
Intraoperative radiation exposure with the use of 18F‐FDG–guided thyroid cancer surgery
Authors: Nalley Charles , Wiebeck Kim , Bartel Twyla B. , Bodenner Donald , Stack Brendan C.
Published: January 2010

Radio‐guided surgery is an established means for surgeons to identify a target of interest for biopsy or excision. This technique is used for a variety of malignancies as well as minimally invasive parathyroid surgery. The primary radionuclide used for these procedures is technetium‐99m (Tc‐99m), but others have been used. Use of 18fluorine‐fluorodeoxyglucose (18F‐FDG) in oncology has proliferated. This has created the opportunity to use 18F‐FDG as a potential radio tracer in the operating room. A pilot study of three patients with non‐iodine avid thyroid cancers undergoing 18F‐FDG–guided revision thyroid cancer surgery is reported. Radiation exposure to operating room personnel was measured. Radiation exposure to the surgeon and staff members of an operating room is well below the limits of the National Regulatory Commission. Therefore, utilization of this radiopharmaceutical intraoperatively should not be limited in the future because of concern regarding exposure of operating room personnel to radiation.
Prevalence of penetration and aspiration on videofluoroscopy in normal individuals without dysphagia
Authors: Allen Jacqui E. , White Cheryl J. , Leonard Rebecca J. , Belafsky Peter C.
Published: January 2010

Objective

To determine the prevalence of penetration and aspiration on videofluoroscopic swallow studies (VFSS) in normal individuals without dysphagia.

Study Design

Case series with planned data collection.

Setting

A tertiary urban university hospital.

Subjects and Methods

Normal adult volunteers without dysphagia, neurological disease, or previous surgery underwent VFSS. Studies were recorded and then reviewed for evidence of penetration or aspiration. The degree of penetration was assessed with the penetration‐aspiration scale (PAS). The effect of age, bolus size, and consistency was evaluated.

Results

A total of 149 VFSS (596 swallows) were reviewed. The mean age of the cohort was 57 years (±19 years); 56 percent were female. Only one (0.6%) individual aspirated on VFSS. Seventeen (11.4%) individuals demonstrated penetration. The mean PAS for the entire cohort was 1.17 (±0.66). Prevalence of penetration by swallow was 2.85 percent (17/596). Prevalence of penetration was 9.3 percent in elderly individuals aged >65 years and 14.3 percent in adults aged <65 years (P = 0.49). Prevalence of penetration on a liquid bolus was 3.4 percent (15/447) and on paste was 1.3 percent (2/149) (P > 0.05). Prevalence of penetration for a bolus <30 cc was 2.34 percent (7/298) and for a bolus >30 cc was 5.4 percent (8/149) (P > 0.05).

Conclusion

Aspiration on VFSS is not a normal finding. Penetration is present in 11.4 percent of normal adults and is more common with a liquid bolus.
From virtual reality to the operating room: The endoscopic sinus surgery simulator experiment
Authors: Fried Marvin P. , Sadoughi Babak , Gibber Marc J. , Jacobs Joseph B. , Lebowitz Richard A. , Ross Douglas A. , Bent John P. , Parikh Sanjay R. , Sasaki Clarence T. , Schaefer Steven D.
Published: January 2010

Objective

Establish the feasibility of a predictive validity study in sinus surgery simulation training and demonstrate the effectiveness of the Endoscopic Sinus Surgery Simulator (ES3) as a training device.

Study Design

Prospective, multi‐institutional controlled trial.

Setting

Four tertiary academic centers with accredited otolaryngology‐head and neck surgery residency programs.

Subjects

Twelve ES3‐trained novice residents were compared with 13 control novice residents.

Methods

Subjects were assessed on the performance of basic sinus surgery tasks. Their first in vivo procedure was video recorded and submitted to a blinded panel of independent experts after the panel established a minimum inter‐rater reliability of 80 percent. The recordings were reviewed by using a standardized computer‐assisted method and customized metrics. Results were analyzed with the Mann‐Whitney U test. Internal rater consistency was verified with Pearson moment correlation.

Results

Completion time was significantly shorter in the experimental group (injection P = 0.003, dissection P < 0.001), which, according to the rater panel, also demonstrated higher confidence (P = 0.009), demonstrated skill during instrument manipulation (P = 0.011), and made fewer technical mistakes during the injection task (P = 0.048) compared with the control group. The raters' post hoc internal consistency was deemed adequate (r > 0.5 between serial measurements).

Conclusion

The validity of the ES3 as an effective surgical trainer was verified in multiple instances, including those not depending on subjective rater evaluations. The ES3 is one of the few virtual reality simulators with a comprehensive validation record. Advanced simulation technologies need more rapid implementation in otolaryngology training, as they present noteworthy potential for high‐quality surgical education while meeting the necessity of patient safety.
Das Mammographie-Screening schafft neue Qualitätskultur im Gesundheitswesen Prävention
Authors: Schultz-Zehden Beate
Published: January 2010

Einleitung

Das Mammographie-Screening ist für über 10 Millionen Frauen zwischen 50 und 69 Jahren die wichtigste Maßnahme zur Brustkrebsfrüherkennung. Ziel des Programms ist es, durch eine frühzeitige Diagnose von Brustkrebs eine schonende und qualifizierte Therapie der bösartigen Tumore zu ermöglichen, die Heilungschancen zu verbessern und die Sterblichkeit an der Erkrankung zu senken. Ergebnisse einer ersten, bundesweiten Befragungsstudie zur Inanspruchnahme, Einstellungen und erste Erfahrungen von Frauen mit diesem neuen Früherkennungsangebot werden vorgestellt.
Häufigkeit ausgewählter überwiegend chronischer Krankheiten als Beispiel für Probleme der Gesundheitsversorgung von morgen
Authors: Beske Fritz
Published: January 2010

Einleitung

Die demografische Entwicklung ist ein entscheidender Faktor für die künftige Gesundheitsversorgung. Dies wird deutlich an der Entwicklung der Morbidität von 22 Krankheiten bis 2050, je nach Datenlage Prävalenz oder Inzidenz. So nimmt die Prävalenz der Makuladegeneration um 125 Prozent zu, die Inzidenz des Herzinfarkts um 75 Prozent, die Inzidenz des Schlaganfalls um 62 Prozent und der Demenz um 113 Prozent. In Verbindung mit der Zunahme der demografiebedingten Multimorbidität steigt der Versorgungsbedarf. Dies erfordert mehr Finanzmittel und mehr Personal. Die Gesundheitspolitik wird sich auf diese Entwicklung einstellen müssen.
THE WORKPLACE, THE SOCIETY AND THE WIDER WORLD: THE OFFSHORING AND OUTSOURCING INDUSTRY
Authors: Hamp-Lyons Liz , Lockwood Jane
Published: January 2010

Workplace language assessment poses special issues for language testers, but also, when it becomes very large scale, it poses issues for language policy. This article looks at these issues, focusing on the offshore and outsourcing (O&O) industry as it is transitioning from native-speaking (NS) countries into nonnative-speaking (NNS) destinations such as India and the Philippines. This is obviously most impacted in call centers, where the ability of customer service representatives (CSRs) to communicate with ease with their native-English speaking customers is central to business success and can be key to a nation's economy. Having reviewed the (limited) research in this area, we take the Philippines as our example to explore how government, academe, and the business sector are dealing with the language proficiency and personnel-training issues caused by the exponential growth in this industry. Appropriate language assessments that are practical, while also being valid and reliable, are critical if the Philippines is to retain its position in this emerging market. Currently, call centers in Philippines complain of very poor recruitment rates due to poor language ability, and of poor quality communication outcomes measures: But how do they assess these key areas? We describe and evaluate the current situation in call center language assessment in the Philippines and discuss possible ways forward, for the Philippines and for the O&O industry more broadly.
Self-Awareness and Saliency of Social Versus Individualistic Behavioral Standards
Authors: Wiekens Carina J. , Stapel Diederik A.
Published: January 2010

In three studies we examined the effects of private and public self-awareness on the saliency of behavioral standards. We used several well-known manipulations to test the effects of private or public self-awareness on the activation of behavioral standards. We expected and found that public self-awareness was related to relatively social standards, such as “getting along well” with others, conveying a positive image, and wanting to be accepted. Private self-awareness was related to the relatively individualistic standard to be authentic and even to being different from others. The consequences of these results are discussed in light of previous research. It is argued that it is important to acknowledge that awareness of different self-aspects may increase saliency of distinct behavioral standards.
What You Did Only Matters if You Are One of Us
Authors: Gollwitzer Mario , Keller Livia
Published: January 2010

Research has demonstrated that repeat offenders are generally punished more severely than first-time offenders. In the present article, we argue that this should particularly be true if the offender is a member of one’s own social category. A group of 86 students were told about a fellow student who hid books from the university library. The student was either an ingroup or an outgroup member and was either a first-time or a repeat offender. As expected, repeat ingroup offenders were more severely punished than first-time ingroup offenders; this effect was mediated by anger/outrage and societal concerns. If the offender was an outgroup member, however, criminal history did not influence punitive reactions.
Predictive Validity of IAT Aggressiveness in the Context of Provocation
Authors: Richetin Juliette , Richardson Deborah South , Mason Gregory D.
Published: January 2010

This study examines the extent to which implicit measures of aggressiveness predict actual aggressive behavior in response to provocation. Participants (n = 77) completed implicit measures of aggressiveness, were or were not exposed to insult from an experimenter, evaluated the performance of the experimenter (i.e., opportunity for aggressive behavior), and completed explicit measures of aggressiveness. Results showed that the implicit measure of aggressiveness significantly predicted aggressive behavior in response to provocation, whereas it was not predictive when there was no provocation. The discussion deals with the validity of implicit measures as predictors of aggressive behavior and their moderators.
Belief Perseverance
Authors: Nestler Steffen
Published: January 2010

Two studies tested the influence of accessibility experiences on belief perseverance when participants generated few or many reasons about how a reported outcome or an alternative outcome might have turned out. Those participants who had listed many reasons about the reported outcome rated this outcome after debriefing to be less likely – and hence exhibited no belief perseverance – than participants who had listed few reasons or subjects in a standard perseverance group (Experiment 1). In contrast, participants who had listed many reasons favoring an alternative outcome rated the reported outcome to be more likely and thus showed more belief perseverance than subjects who had listed only few reasons or participants in a standard perseverance condition (Experiment 2). Both effects are interpreted as evidence for the influence of accessibility experiences in the domain of belief perseverance.
The Effects of Judge-Target Gender and Ethnicity Similarity on the Accuracy of Personality Judgments
Authors: Letzring Tera D.
Published: January 2010

One factor that may affect the accuracy of personality judgment is the level of similarity between the judge and the target. In the current study, judges observed four targets with different levels of gender and ethnicity (GE) similarity (same gender and ethnicity, only same gender, only same ethnicity, different gender and ethnicity). Judge-target GE similarity was positively related to the accuracy of personality judgment among female judges, but not among male judges. It was also found that females were both more accurate judges and more accurately judged, but that the combination of both a female judge and a female target only had an additive effect on accuracy. Projection was also related to accuracy. These findings suggest that among the several factors that can be used to predict accuracy, judge-target similarity, gender of the judge, gender of the target, and projection of the judge’s personality onto the target are important.
The Effects of Mortality Salience and Social Dominance Orientation on Attitudes Toward Illegal Immigrants
Authors: Bassett Jonathan F.
Published: January 2010

The paper examines the hypothesis that the effects of mortality salience on attitudes toward illegal immigrants are moderated by individual differences predisposing participants toward prejudice or intolerance. A total of 122 university students completed measures of political orientation, authoritarianism, and social dominance orientation prior to being randomly assigned to a mortality salience or control condition. Political conservatism, authoritarianism, and social dominance orientation were all associated with more negative attitudes toward illegal immigrants. Although there was no main effect for mortality salience, there was an interaction between mortality salience and social dominance orientation. Higher social dominance orientation was associated with more negative attitudes toward illegal immigrants, albeit only in the mortality salience condition.
Changing links between South Asian summer monsoon circulation and tropospheric land‐sea thermal contrasts under a warming scenario
Authors: Sun Ying , Ding Yihui , Dai Aiguo
Published: January 2010

Forced with increased greenhouse gases, the South Asian summer monsoon (SASM) circulation weakens in climate models, which appears inconsistent with the projected increases in near‐surface land‐sea thermal contrasts during the 21st century. Our analysis shows that the SASM intensity positively correlates with the land‐sea thermal contrast in both the lower‐ and upper‐troposphere before year 2000; thereafter a reduced upper‐tropospheric thermal contrast leads to a weakened SASM circulation, despite an increasing lower‐tropospheric thermal contrast. The decrease in the upper‐tropospheric thermal contrast mainly results from enhanced upper‐tropospheric warming over the tropical Indian Ocean due to increased latent heating. The results suggest a crucial role of enhanced tropical convection in the weakening of SASM circulation and a weak influence of lower‐tropospheric thermal contrast on the SASM under global warming. They also imply a less important role of near‐surface processes over the Tibetan Plateau in the long‐term SASM change during the 21st century.
Joint retrieval of surface reflectance and aerosol optical depth from MSG/SEVIRI observations with an optimal estimation approach: 2. Implementation and evaluation
Authors: Wagner S. C. , Govaerts Y. M. , Lattanzio A.
Published: January 2010

An original method, based on optimal estimation, was presented in a part one of this paper for the joint retrieval of the mean daily total column aerosol optical depth and the surface Bidirectional Reflectance Factor (BRF) from the daily accumulated Meteosat Second Generation–Spinning Enhanced Visible and Infrared Imager (MSG/SEVIRI) observations in the solar channels. The objective of this paper is to evaluate the benefits of the proposed approach and to document the limits of the algorithm assumptions in the context of its implementation in an operational ground segment. A twofold approach is followed. In a first step, by looking at the posterior correlation error matrix the capability of the so‐called Land Daily Aerosol (LDA) algorithm to decouple the surface‐atmosphere signal is analyzed. In particular, the impact of the prior information is investigated in detail. In a second step, the results of the algorithm are compared with independent data sets of aerosol optical depth and surface reflectance. In this phase, the accuracy of the algorithm is evaluated against ground observations from the AERONET network. LDA is shown to be in good agreement with these data, especially when the prior update mechanism is activated. Comparisons with the MODIS surface product showed that the bihemispherical reflectance derived from the LDA products is consistent with the equivalent MODIS white‐sky albedo. Aerosol spatial distributions are comparable in terms of geographical location and intensity, in particular for aerosol episodes with a limited daily variation.
Brilliant reversible luminescent mechanochromism of silver(i) complexes containing o-bis(diphenylphosphino)benzene and phosphinesulfide
Authors: Tsukuda Toshiaki , Kawase Marina , Dairiki Ayumi , Matsumoto Kenji , Tsubomura Taro
Published: January 2010

When the blue-emitting crystals (1b) of Ag(i) complexes coordinated by o-bis(diphenylphosphino)benzene were ground, the emitting color of the solid changes into green (1g). The emitting color of 1g returned to blue on either heating or recrystallization.
Acetylation of cyclin A: a new cell cycle regulatory mechanism
Authors: Mateo Francesca , Vidal-Laliena Miriam , Pujol Maria Jesus , Bachs Oriol
Published: January 2010

Cyclin A must be degraded at prometaphase in order to allow mitosis progression. Nevertheless, the signals that trigger cyclin A degradation at mitosis have been largely elusive. In the present paper, we review the status of cyclin A degradation in the light of recent evidence indicating that acetylation plays a role in cyclin A stability. The emerging model proposes that the acetyltransferase PCAF [p300/CREB (cAMP-response-element-binding protein)-binding protein-associated factor] [perhaps also its homologue GCN5 (general control non-derepressible 5)] acetylates cyclin A at Lys54, Lys68, Lys95 and Lys112 during mitosis, leading to its ubiquitylation by the anaphase-promoting factor/cyclosome and its subsequent degradation via proteasome. Interestingly, these four lysine residues in cyclin A also participate in the regulation of cyclin A–Cdk (cyclin-dependent kinase) activity by modulating its interaction with Cdks.
Strategies for the identification of ubiquitin ligase inhibitors
Authors: Goldenberg Seth J. , Marblestone Jeffrey G. , Mattern Michael R. , Nicholson Benjamin
Published: January 2010

Dysregulation of the UPS (ubiquitin–proteasome system) has been implicated in a wide range of pathologies including cancer, neurodegeneration and viral infection. Inhibiting the proteasome has been shown to be an effective therapeutic strategy in humans; however, toxicity with this target remains high. E3s (Ub–protein ligases) represent an alternative attractive therapeutic target in the UPS. In this paper, we will discuss current platforms that report on E3 ligase activity and can detect E3 inhibitors, and underline the advantages and disadvantages of each approach.
The therapeutic potential of deubiquitinating enzyme inhibitors
Authors: Colland Frédéric
Published: January 2010

Proteases play a key role in various pathological processes and several protease inhibitors are already available for treatment. DUBs (deubiquitinating enzymes) constitute one of the largest classes of human proteases and are key effectors of the ubiquitin–proteasome system. This pathway regulating cellular protein turnover has been implicated in the pathogenesis of many human diseases, including neurodegenerative disorders, viral diseases and cancer. The therapeutic efficacy of the proteasome inhibitor Velcade® (bortezomib) for treating multiple myeloma and mantle cell lymphoma establishes this system as a valid target for cancer treatment. A promising alternative to targeting the proteasome itself would be to target the upstream, ubiquitin conjugation/deconjugation system, to generate more specific, less toxic anticancer agents. Advances in small molecule-based inhibitors specifically targeting DUBs are presented in this review.
Nucleocytoplasmic transport in yeast: a few roles for many actors
Authors: Fiserova Jindriska , Goldberg Martin W.
Published: January 2010

Eukaryotic cells have developed a series of highly controlled processes of transport between the nucleus and cytoplasm. The present review focuses on the latest advances in our understanding of nucleocytoplasmic exchange of molecules in yeast, a widely studied model organism in the field. It concentrates on the role of individual proteins such as nucleoporins and karyopherins in the translocation process and relates this to how the organization of the nuclear pore complex effectively facilitates the bidirectional transport between the two compartments.
Lamins as cancer biomarkers
Authors: Foster Clare R. , Przyborski Stefan A. , Wilson Robert G. , Hutchison Christopher J.
Published: January 2010

Lamins are multifunctional proteins that are often aberrantly expressed or localized in tumours. Here, we endeavour to assess their uses as cancer biomarkers: to diagnose tumours, analyse cancer characteristics and predict patient survival. It appears that the nature of lamin function in cancer is very complex. Lamin expression can be variable between and even within cancer subtypes, which limits their uses as diagnostic biomarkers. Expression of A-type lamins is a marker of differentiated tumour cells and has been shown to be a marker of good or poor patient survival depending on tumour subtype. Further research into the functions of lamins in cancer cells and the mechanisms that determine its patterns of expression may provide more potential uses of lamins as cancer biomarkers.
The plant nuclear envelope in focus
Authors: Graumann Katja , Evans David E.
Published: January 2010

Recent progress in understanding the plant NE (nuclear envelope) has resulted from significant advances in identifying and characterizing the protein constituents of the membranes and nuclear pores. Here, we review recent findings on the membrane integral and membrane-associated proteins of the key domains of the NE, the pore domain and inner and outer NEs, together with information on protein targeting and NE function.
Synthesis and field emission properties of nanocrystalline diamond/carbon nanowall composite films
Authors: Teii Kungen , Nakashima Masahiro
Published: January 2010

Nanostructured composite films consisting of almost vertically aligned graphene layers, so-called “carbon nanowalls” (CNWs), and nanocrystalline diamond films are prepared by plasma-enhanced chemical vapor deposition. The space between the walls for the composite films is widened compared to simple CNWs by interception of in-plane continuity of the wall structures. The nucleation density of diamond is responsible for the spacing and arrangement of the walls. Field emission measurements show that the composite films have lower turn-on fields (∼1 V/μm) and larger field enhancement factors (∼4000) than simple CNWs. The results indicate that electric field screening between neighboring walls is well suppressed.
Polymer field-effect transistors based on semiconducting polymer heterojunctions
Authors: Liu Chuan , Sirringhaus Henning
Published: January 2010

Top-gate polymer field-effect transistors based on charge accumulation in bilayers of two semiconducting polymers have been realized. Holes were confined at the interface between poly(3-hexyl thiophene) (P3HT) and a series of semiconducting polymers with ionization potential higher than P3HT. In contrast to conventional devices based on semiconductor-dielectric interfaces the current was found to saturate at high gate voltages. The more pronounced the current saturation is, the lower the applied source-drain voltage. Generic drift-diffusion device simulations were performed to explain this behavior in terms of the competing processes of charge transport along and charge transfer across the bilayer interface. Our results indicate that in order to block the charge transfer across the heterojunction the offset between the ionization potential of the two polymers needs to be at least 1.0 eV.
Molecular dynamics simulations of nonpolarizable inorganic salt solution interfaces: NaCl, NaBr, and NaI in transferable intermolecular potential 4-point with charge dependent polarizability (TIP4P-QDP) water
Authors: Bauer Brad A. , Patel Sandeep
Published: January 2010

We present molecular dynamics simulations of the liquid-vapor interface of 1M salt solutions of nonpolarizable NaCl, NaBr, and NaI in polarizable transferable intermolecular potential 4-point with charge dependent polarizability water [B. A. Bauer et al., J. Chem. Theory Comput. 5, 359 (2009)]; this water model accommodates increased solvent polarizability (relative to the condensed phase) in the interfacial and vapor regions. We employ fixed-charge ion models developed in conjunction with the TIP4P-QDP water model to reproduce ab initio ion-water binding energies and ion-water distances for isolated ion-water pairs. The transferability of these ion models to the condensed phase was validated with hydration free energies computed using thermodynamic integration (TI) and appropriate energy corrections. Density profiles of Cl−, Br−, and I− exhibit charge layering in the interfacial region; anions and cation interfacial probabilities show marked localization, with the anions penetrating further toward the vapor than the cations. Importantly, in none of the cases studied do anions favor the outermost regions of the interface; there is always an aqueous region between the anions and vapor phase. Observed interfacial charge layering is independent of the strength of anion-cation interactions as manifest in anion-cation contact ion pair peaks and solvent separated ion pair peaks; by artificially modulating the strength of anion-cation interactions (independent of their interactions with solvent), we find little dependence on charge layering particularly for the larger iodide anion. The present results reiterate the widely held view of the importance of solvent and ion polarizability in mediating specific anion surface segregation effects. Moreover, due to the higher parametrized polarizability of the TIP4P-QDP condensed phase {1.31 Å3 for TIP4P-QDP versus 1.1 Å3 (TIP4P-FQ) and 0.87 Å3 (POL3) [Ponder and Case, Adv. Protein Chem. 66, 27 (2003)]} based on ab initio calculations of the condensed-phase polarizability reduction in liquid water, the present simulations highlight the role of water polarizability in inducing water molecular dipole moments parallel to the interface normal (and within the interfacial region) so as to favorably oppose the macrodipole generated by the separation of anion and cation charge. Since the TIP4P-QDP water polarizability approaches that of the experimental vapor phase value for water, the present results suggest a fundamental role of solvent polarizability in accommodating the large spatial dipole generated by the separation of ion charges. The present results draw further attention to the question of what exact value of condensed phase water polarizability to incorporate in classical polarizable water force fields.
Correlation between morphology and performance of low bandgap oligothiophene:C60 mixed heterojunctions in organic solar cells
Authors: Wynands D. , Levichkova M. , Riede M. , Pfeiffer M. , Baeuerle P. , Rentenberger R. , Denner P. , Leo K.
Published: January 2010

We investigate the end-capped oligothiophene derivative α,ω-bis-(dicyanovinylene)-sexithiophene with ethyl side chains (DCV6T) as donor material in heterojunctions with C60. The effect of the substrate temperature on the morphology and related photophysical properties of single DCV6T and mixed DCV6T:C60 layers is investigated. Single layers of DCV6T show crystalline features in UV-visible absorption and x-ray diffraction when grown on a substrate heated to 90°C. Investigations of DCV6T:C60 mixed layers by atomic force microscopy, UV-visible absorption, and photoluminescence measurements reveal that the elevated substrate temperature induces an increased phase separation between the two materials with larger domain size and higher surface roughness. Based on these observations, we present mixed heterojunction solar cells where the power conversion efficiency (ηPCE) is increased from 1.6% to 3.8% by increasing the substrate temperature from 30to90°C, respectively.
Modeling of field- and time-dependent resistance change phenomena under electrical stresses in Fe–O films
Authors: Eriguchi Koji , Wei Zhiqiang , Takagi Takeshi , Ono Kouichi
Published: January 2010

An electrical stress-induced resistance change in an Fe–O film was studied in detail. Under constant voltage stress (CVS) and constant current injection, the resistance of the Fe–O film abruptly increased. The observed time-to-resistance increase (tr) was found to depend on the applied voltage as well as on the injected current density. The total input energy until tr also depended on the applied voltage. From these observations, the mechanisms of resistance change are considered to obey a field-enhanced reaction, and this resistance increase is attributed to a high-resistive Fe–O layer formation at the interface between the anode electrode and the low-resistive Fe–O layer. We proposed a simplified two-step model for the time evolution of the current under CVS [ICVS(t)]. The predicted ICVS(t) showed a good agreement with experimental results. The model also explained the field dependence of tr.
Hard graphitelike hydrogenated amorphous carbon grown at high rates by a remote plasma
Authors: Singh S. V. , Zaharia T. , Creatore M. , Groenen R. , Van Hege K. , van de Sanden M. C. M.
Published: January 2010

Hydrogenated amorphous carbon (a-C:H) deposited from an Ar-C2H2 expanding thermal plasma chemical vapor deposition (ETP-CVD) is reported. The downstream plasma region of an ETP is characterized by a low electron temperature (∼0.3 eV), which leads to an ion driven chemistry and negligible physical effects, such as ion bombardment (ion energy <2 eV) on the depositing surface. The material properties in ETP-CVD can be controlled by varying the plasma chemistry. In this article we investigate the change in a-C:H material properties by varying the Ar/C2H2 gas flow ratio over a wide range (1.33–150), with emphasis on low gas flow ratios (1.33–5). By changing the Ar/C2H2 gas flow ratio, the gas residence time in the ETP expansion can be tuned, which in turn defines the chemistry of the ETP-CVD. Soft polymerlike a-C:H to moderately hard a-C:H films have been deposited by lowering the Ar/C2H2 gas flow ratio. Recently, under very low Ar/C2H2 gas flow ratios, a hard graphitelike a-C:H material has been deposited. The striking feature of this material is the infrared absorption spectrum in the CHx stretching region (2800–3100 cm−1), which is a distinct narrow bimodal spectrum evolving from a broad spectrum for the moderately hard a-C:H. This transition was attributed to the absence of end groups (sp2 CH2 and sp3 CH3), which favors an enhanced cross-linking in the film in a similar effect to elevated ion bombardment or annealing. Moreover, the hard graphitelike film has an increased refractive index (n) as high as 2.5 at 633 nm with a corresponding mass density of ∼2.0 g/cm3.
Contributions of domain wall motion to complex electromechanical coefficients of 0.62Pb(Mg1/3Nb2/3)O3–0.38PbTiO3 crystals
Authors: Wang Zhu , Zhang Rui , Sun Enwei , Cao Wenwu
Published: January 2010

The loss behavior of 0.62Pb(Mg1/3Nb2/3)O3–0.38PbTiO3 (PMN-38%PT) ferroelectric single crystal poled along [001]c was investigated. It was found that the complex electromechanical coefficients and loss factors change dramatically at the coercive field Ec around 250 V/mm, representing the intrinsic switching barrier. Since the energy loss is related to the domain wall motion, the imaginary parts of the electromechanical coefficients can be used to study the degree of domain wall motions in relaxor-based ferroelectric single crystals. Experimental results indicate that for this system, domain wall motion contributes significantly to the imaginary parts of electromechanical coefficients. In addition, [001]c poled PMN-38%PT single crystals have much larger mechanical loss factor compared to that of conventional single crystal like LiNbO3. This phenomenon is proved to be closely related to 90° domain wall motion in this crystal system.
Structure and magnetic properties of detonation nanodiamond chemically modified by copper
Authors: Shames A. I. , Panich A. M. , Osipov V. Yu. , Aleksenskiy A. E. , Vul’ A. Ya. , Enoki T. , Takai K.
Published: January 2010

We report on detailed study of detonation nanodiamonds (DNDs) whose surface has been chemically modified by copper with the aid of ion exchange in water DND suspension. High resolution transmission electron microscopy, Raman, IR, electron magnetic resonance (EMR), nuclear magnetic resonance (NMR), and superconducting quantum interference device techniques were used for the characterization of DND. Carboxyl groups, appearing on the surface of a nanodiamond particle during its synthesis and purification processes, provide an effective binding of divalent copper ions to the surface. The binding results from the ion exchange between metal cations and protons of surface carboxyl groups in water solutions. IR data evidence the presence of multiple COC groups in the dried copper-modified DND product. Both EMR and C13 NMR provide direct evidences of the appearance of isolated Cu2+ ions on the surface of the 5 nm nanodiamond particles. EMR spectra reveal well-pronounced hyperfine structure due to C63,65u nuclear spin I=3/2 with the spectral pattern which is typical for mononuclear axially distorted Cu2+ complexes in polycrystals. Using Cu2+ ions as paramagnetic probes two-component model of carbon inherited paramagnetic centers in DND is suggested. Magnetic susceptibility for all samples follows the Curie–Weiss law above 30 K. The concentration of magnetically observable copper ions Cu2+ (spin S=1/2) localized on the nanodiamonds surface increases up to approximately 1.5–3.5 ions per nanoparticle with increasing concentration of copper acetate in starting solutions.
Broadband dielectric response and grain-size effect in K0.5Na0.5NbO3 ceramics
Authors: Buixaderas E. , Bovtun V. , Kempa M. , Savinov M. , Nuzhnyy D. , Kadlec F. , Vaněk P. , Petzelt J. , Eriksson M. , Shen Z.
Published: January 2010

Dielectric spectra of two K0.5Na0.5NbO3 ceramics with different grain sizes (10 and 0.5 μm) were measured from 102 to 1014 Hz in a broad temperature range. The sequence of first-order phase transitions (cubic-tetragonal-orthorhombic-rhombohedral) was detected by differential scanning calorimetry, dielectric spectroscopy, and time-domain terahertz spectroscopy. The grain size affects all the phase transitions, which are more smeared in the small-grain sample. In the large-grain ceramics, two well-separated near-Debye relaxations are seen in the tetragonal phase, which suddenly merge on cooling across the tetragonal-orthorhombic transition, and on further cooling the lower-frequency relaxation strongly broadens. On reducing the grain size, the higher-frequency relaxation shifts from ∼1 to ∼20 GHz and the lower-frequency one strongly broadens. Without quantitative understanding, these effects could be assigned to domain-wall dynamics and its temperature and grain-size dependences. Similar to pure KNbO3, an overlapped central-mode–soft-mode type excitation was detected in the terahertz range related to the effective hopping and oscillations of the off-centered Nb ions in a multiwell potential.
Kirkwood–Buff derived force field for alkali chlorides in simple point charge water
Authors: Klasczyk Benjamin , Knecht Volker
Published: January 2010

Solvated ions are a fundamental constituent of many biological systems. An important class consists of the alkali cations. In particular, potassium (K+) is the most abundant ion in the cytoplasm, whereas lithium (Li+), rubidium (Rb+), and cesium (Cs+) are of fundamental physicochemical and medical relevance. A powerful tool to understand ion specificity and cellular systems on a microscopic level is provided by molecular dynamics simulations. Previously, reliable force field parameters for Li+, K+, Rb+, and Cs+ in aqueous solution have not been available for the simple point charge (SPC) water model widely used in conjunction with the GROMOS force field. We used the Kirkwood–Buff theory to develop force fields for Li+, K+, Rb+, and Cs+ in SPC water to reproduce experimental data on respective aqueous alkali chloride solutions (LiCl, KCl, RbCl, CsCl). The force field developed reproduces many of the known properties of alkali metal chlorides solutions including densities and partial molar volumes. Our force field is shown to be superior to other common alkali chloride force fields in terms of reproducing the activity derivative, as a prerequisite for a realistic measure of ion-solute association underlying ion-specific phenomena (Hofmeister effects). For lithium and potassium, the ionic radii from cation-water oxygen pair correlation functions and hydration numbers are well reproduced. The force field developed will be useful for modeling physiological conditions and ion-specific phenomena for biomolecular systems.
Homogeneous nucleation of a homologous series of n-alkanes (CiH2i+2, i=7–10) in a supersonic nozzle
Authors: Ghosh David , Bergmann Dirk , Schwering Regina , Wölk Judith , Strey Reinhard , Tanimura Shinobu , Wyslouzil Barbara E.
Published: January 2010

Homogeneous nucleation rates of the n-alkanes (CiH2i+2; i=7–10) were determined by combining information from pressure trace measurements and small angle x-ray scattering (SAXS) experiments in a supersonic Laval nozzle. The condensible vapor pressure pJ max, the temperature TJ max, the characteristic time ΔtJ max, and supersaturation SJ max corresponding to the peak nucleation rate Jmax were determined during the pressure trace measurements. These measurements also served as the basis for the subsequent SAXS experiments. Fitting the radially averaged SAXS spectrum yielded the mean droplet radius ⟨r⟩, 5<⟨r⟩/nm<31, the width of the aerosol size distribution σ, 2<σ/nm<6, and the particle number density N, 7×1010<N/cm−3<2.2×1012. The nucleation rates for the n-alkanes Jmax, 4×1015<Jmax/cm−3 s−1<2×1018, vary by almost three orders of magnitude as the temperature TJmax decreases from ∼200 K to as low as 150 K. At the lowest temperatures, the supersaturations SJmax are on the order of 105. In spite of these extreme operating conditions, we find good agreement between the current experimental results and those available in the literature using Hale’s scaling formalism [Phys. Rev. A 33, 4156 (1986); Metall. Trans. A 23, 1863 (1992)] and the scaling parameters reported by Rusyniak and El-Shall [J. Phys. Chem. B 105, 11873 (2001)]. Comparing the experimental nucleation rates with the predictions of classical nucleation theory, we find that our experimental nucleation rates are 4.5–8 orders of magnitude higher than the predictions.
Strongly contracted canonical transformation theory
Authors: Neuscamman Eric , Yanai Takeshi , Chan Garnet Kin-Lic
Published: January 2010

Canonical transformation (CT) theory describes dynamic correlation in multireference systems with large active spaces. Here we discuss CT theory’s intruder state problem and why our previous approach of overlap matrix truncation becomes infeasible for sufficiently large active spaces. We propose the use of strongly and weakly contracted excitation operators as alternatives for dealing with intruder states in CT theory. The performance of these operators is evaluated for the H2O, N2, and NiO molecules, with comparisons made to complete active space second order perturbation theory and Davidson-corrected multireference configuration interaction theory. Finally, using a combination of strongly contracted CT theory and orbital-optimized density matrix renormalization group theory, we evaluate the singlet-triplet gap of free base porphin using an active space containing all 24 out-of-plane 2p orbitals. Modeling dynamic correlation with an active space of this size is currently only possible using CT theory.
Two-side surface photovoltage studies for implanted iron diffusion in silicon during rapid thermal anneal
Authors: Rapoport I. , Taylor P. , Kearns J. , Schroder D. K.
Published: January 2010

Two-side surface photovoltage (TS-SPV) based on measuring SPV from both wafer sides is proposed as the approach for silicon iron contamination monitoring. TS-SPV is applied to follow diffusion of implanted iron in a lightly doped p-type silicon during rapid thermal anneal (RTA). Good correlation is found between the iron distribution versus RTA conditions in the range of 375–1100°C. The impact of thermal donors in silicon after RTA at below 700°C is illustrated. The portion of iron detectable by SPV (FeB pairs) is found as a function of RTA time and temperature. Iron diffusion activation energy was evaluated for the interstitial ionized iron Fei+ and for the interstitial neutral iron Fei0. Low thermal budget RTA combined with TS-SPV has been proven to be an effective iron contamination monitor to identify contamination sources, character, and location.