bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of multilevel upper airway surgery on continuous positive airway pressure therapy in obstructive sleep apnea/hypopnea syndrome
Authors: Friedman Michael , Soans Rohit , Joseph Ninos , Kakodkar Samir , Friedman Jacob
Published: January 2009

Objective:

To investigate the effect of multilevel upper airway surgery (USA) on subsequent continuous positive airway pressure (CPAP) therapy in patients with obstructive sleep apnea/hypopnea syndrome (OSAHS).

Study Design:

Fifty‐two patients who underwent multilevel UAS with persistent symptoms of OSAHS represent the cohort for this study. All patients had undergone manual CPAP titrations both pre‐ and postoperatively. Patients were used as their own controls and were compared pre‐ and postoperatively with regard to body mass index, full night polysomnography (PSG), optimal CPAP pressure settings, presence of rapid eye‐movement (REM) sleep, identification of mouth leakage, and CPAP compliance.

Results:

Postoperative values for apnea index (AI), apnea hypopnea index (AHI), and minimum oxygen saturation (min SaO2) were all significantly decreased from their preoperative levels. Compliance with CPAP therapy significantly increased from a mean 0.02 ± 0.14 hours per night prior to surgery to a 3.2 ± 2.6 hours per night following surgery (P < .001). In addition, the optimal CPAP pressure setting decreased significantly for a preoperative value of 10.6 ± 2.1 cm H2O to 9.8 ± 2.1 cm H2O following surgery. Fifty of the 52 patients (96.2%) studied were able to maintain optimal pressure settings without mouth leak, postoperatively.

Conclusions:

In this study, most patients who had persistent symptoms of OSAHS after multilevel UAS did not have significant mouth leak that would preclude CPAP therapy. In this cohort of patients, CPAP pressure setting as well as compliance was significantly improved postoperatively. Laryngoscope, 119:193–196, 2009
Minimally invasive endoscopic pericranial flap: A new method for endonasal skull base reconstruction
Authors: Zanation Adam M. , Snyderman Carl H. , Carrau Ricardo L. , Kassam Amin B. , Gardner Paul A. , Prevedello Daniel M.
Published: January 2009

Objectives:

One of the major challenges of cranial base surgery is reconstruction of the dural defect. Following a craniofacial resection, the standard reconstructive technique is direct suture repair of the dural defect with a fascial graft and rotation of an anteriorly based pericranial scalp flap to cover the dura. The introduction of endoscopic techniques and an endonasal approach to the ventral skull base has created new challenges for reconstruction. The nasoseptal flap has become the workhorse for vascularized endoscopic skull base reconstruction; however at times, the septal mucosal flap may be unavailable for reconstruction. This can be due to prior surgical resection or involvement of the nasal septum by sinonasal cancer. We have developed a minimally invasive endoscopic pericranial flap for endoscopic skull base reconstruction. The use of a pericranial scalp flap for reconstruction during endonasal skull base surgery using minimally invasive techniques has not been previously reported.

Methods:

We performed cadaveric studies to illustrate feasibility of an endoscopic pericranial flap for endonasal skull base reconstruction, then applied this novel technique to an elderly patient after endonasal skull base and dural resection of an esthesioneuroblastoma.

Results:

The technical report of the minimally invasive pericranial flap is outlined and the advantages and limitations during endonasal skull base reconstruction are discussed. The patient had excellent healing of her skull base and had no evidence of any postoperative cerebrospinal fluid leak.

Conclusions:

The minimally invasive endoscopic pericranial flap provides another option for endonasal reconstruction of cranial base defects. There is minimal donor site morbidity, and it provides a large flap that can cover the entire ventral skull base. The issues of intranasal tissue tumor involvement and the need for radiotherapy make the endoscopic pericranial flap an ideal reconstruction for anterior cranial base defects resulting from endonasal sinonasal and skull base cancer resections. Laryngoscope, 119:13–18, 2009
Destructive otomastoiditis by MRSA from porcine origin
Authors: Van Hoecke Helen , Piette Anne , De Leenheer Els , Lagasse Nathalie , Struelens Marc , Verschraegen Gerda , Dhooge Ingeboy
Published: January 2009

A 63‐year‐old female pig farmer was referred to our department with a protracted course of otomastoiditis with destruction of the tympanic roof and cerebrospinal fluid leakage. The patient underwent a cortical mastoidectomy with closure of a large dural defect. Cultures of the middle ear effusion yielded a methicillin‐resistant Staphylococcus aureus (MRSA), which upon further analysis was found to be from porcine origin. To our knowledge, this is the first report of a complicated case of otomastoiditis caused by a pig‐type MRSA. Laryngoscope, 119:137–140, 2009
Nanocomposite‐Beschichtungen auf CBN‐Werkzeugen
Authors: Frank H. , Reich S.
Published: January 2009

CBN (cubic boron nitride)‐Schneidstoffe werden eingesetzt, um die Gebrauchseigenschaften von Zerspanwerkzeugen zu verbessern und damit in Anwendungsbereiche vorzudringen, die mit herkömmlichen Schneidstoffen bisher nicht erreichbar waren (z. B. Hartzerspanung). Eine Beschichtung der CBN‐Schneidstoffe erfolgt üblicherweise zur optischen Beurteilung des Verschleißzustandes. Zur weiteren Verbesserung der Gebrauchseigenschaften eingesetzter CBN‐Werkzeuge wurde eine entsprechende Beschichtungstechnologie erarbeitet, welche die guten Zerspaneigenschaften von CBN‐Schneidstoffen mit den hervorragenden Eigenschaften von nanostrukturierten Beschichtungen kombiniert. Verschiedene Schichtsysteme und Vorbehandlungsmöglichkeiten der CBN‐Werkzeuge wurden überprüft.

Im Rahmen der Untersuchungen konnte gezeigt werden, dass mit einer Nanocomposite‐Beschichtung eine signifikante Verbesserung der Werkzeugstandzeit von CBN‐Werkzeugen erreicht werden kann. Allerdings kommt der Gewährleistung einer hohen Schichthaftung mittels spezieller Haftvermittlerschichten und durch eine entsprechend optimierte Schichtstruktur eine besondere Bedeutung zu.
Verifizierung numerischer Verfahren zur Modellierung abrasiver Verschleißprozesse durch Berechnung von Scratchtests
Authors: Wielage B. , Lampke Th. , Müller T. , Weber D.
Published: January 2009

Die Abrasion ist ein grundlegender Verschleißmechanismus. Sie tritt immer dann auf, wenn Oberflächen durch harte Partikel oder Rauheitsspritzen tribologisch beansprucht werden. Der Scratchtest gibt über das Verhalten einer Oberfläche bei abrasiver Belastung Auskunft. Dazu wird eine Diamantspitze (Indenter) entweder mit konstanter oder progressiver Normalkraft über das Material bewegt. Es kommt zunächst zu elastischer, im Weiteren auch zu plastischer Verformung bis hin zur Riss‐ und Spanbildung, je nach Duktilität des Materials. Anhand von elastischer und plastischer Eindringtiefe, Reibkraft, akustischer Emission durch Rissbildung sowie der dreidimensionalen Auswertung des Ritzes kann der Verschleißwiderstand gegenüber ritzender Beanspruchung charakterisiert werden.

Die Simulation von Scratchtests dient zur Überprüfung von Materialmodellen, indem Simulations‐ und Versuchsergebnisse, die relativ leicht und schnell erzielbar sind, verglichen werden. Anhand der Ergebnisse lassen sich bestehende Werkstoffkonzepte auf die Anwendungen noch besser anpassen bzw. entwickeln.

Der Beitrag beschreibt Probleme und Lösungsansätze bei der Umsetzung der Simulation des Scratchtestes für den Stahl C45 (normalisiert). Durch den Vergleich mit experimentell ermittelten Ergebnissen wird gezeigt, dass die Vorgehensweise bei der Modellbildung und Simulation zielführend ist. Im Weiteren soll ein geschlossenes Werkstoffmodell für diese Beanspruchungsart entwickelt werden.
In Metalloberflächen verankerte Polymere zur Herstellung ultrahydrophober Metalloberflächen
Authors: Höhne S. , Frenzel R. , Blank C. , Thieme M. , Worch H. , Heppe A. , Simon F.
Published: January 2009

In einem zweistufigen Verfahren wurden Metall‐ bzw. Metalloxidoberflächen so modifiziert, dass sie ultrahydrophobe und damit selbstreinigende Eigenschaften aufwiesen. Zum Erreichen der Ultrahydrophobie auf Aluminium war zunächst ein Aufrauen der Oberflächen erforderlich, das durch eine anodische Oxidation realisiert wurde. In die sich ausbildende Oberflächenschicht ließ sich unter geeigneten Bedingungen Chitosan kathodisch so abscheiden, dass eine formschlüssige Verbindung entstand. Das inkorporierte Chitosan verlieh durch seine reaktiven Aminogruppen der Kompositoberfläche eine hohe Reaktivität gegenüber Elektrophilen und ermöglichte so eine Oberflächenfunktionalisierung, die zur Generierung der gewünschten Oberflächeneigenschaften genutzt werden konnte. Durch das Umsetzen der Aminogruppen mit Carbonylverbindungen konnten unter Ausnutzung von Selbstorganisationsprinzipien ultrahydrophobe Oberflächen hergestellt werden.
Kontaktwerkstoffe auf Silberbasis ‐ Gefüge und mechanische Eigenschaften
Authors: Wielage B. , Steger H. , Podlesak H. , Lampke Th.
Published: January 2009

Als Schalter‐Kontaktwerkstoffe für Relais und Schütze werden verschiedene Silberbasiswerkstoffe eingesetzt. Dabei kommt den Silberbasis‐Verbundwerkstoffen eine besondere Bedeutung zu. Zur Herstellung dieser Verbundwerkstoffe im Industriemaßstab werden aktuell die konventionellen Verfahren Pulvermischen und Nasschemisches Fällen in Verbindung mit der anschließenden pulvermetallurgischen Verarbeitung zu Drähten angewendet. Zur Herstellung der Silberbasis‐Verbundwerkstoffe mit vergleichbarem Gefüge wird die Eignung von alternativen Herstellungsrouten geprüft. Der vorliegende Beitrag zeigt das Potenzial der Verfahren Hochenergiekugelmahlen und Intensivmischen gegenüber den beiden üblichen Verfahren auf. Das Hauptaugenmerk liegt auf der Beurteilung des Gefüges von Verbundpulver und Strangpressdraht hinsichtlich der Verteilung der Verstärkungskomponente und der resultierenden mechanischen Eigenschaften des Drahtmaterials.
Amyotrophic lateral sclerosis and neurosarcoidosis: A case report
Authors: Chen I‐Hweii Amy , Mitsumoto Hiroshi , Vonsattel Jean P. , Hays Arthur P.
Published: January 2009

Amyotrophic lateral sclerosis (ALS) remains a clinical diagnosis without definable biomarkers. The pathomechanism of motor neuron degeneration in ALS has yet to be elucidated. Here we present a case of limb‐onset ALS, with autopsy findings of Bunina bodies and skein‐like inclusions, as well as sarcoid granulomas predominating among motor neurons. The targeting of the motor neurons by the sarcoid inflammation raises questions regarding the role of cellular immunity in the pathomechanisms for ALS. Muscle Nerve, 2009
Needle electromyography
Authors: Daube Jasper R. , Rubin Devon I.
Published: January 2009

Physiologic assessment of diseases of the motor unit from the anterior horn cells to the muscles relies on a combination of needle electromyography (EMG) and nerve conduction studies (NCS). Both require a unique combination of knowledge of peripheral nervous system anatomy, physiology, pathophysiology, diseases, techniques, and electricity is necessary. Successful, high‐quality, reproducible EMG depends on the skills of a clinician in patient interaction during the physical insertion and movement of the needle while recording the electrical signals. These must be combined with the skill of analyzing electric signals recorded from muscle by auditory pattern recognition and semiquantitation.10, 52 This monograph reviews the techniques of needle EMG and waveform analysis and describes the types of EMG waveforms recorded during needle EMG. © 2009 Wiley Periodicals, Inc. Muscle Nerve 39: 244–270, 2009
Lewis–sumner syndrome of pure upper‐limb onset: Diagnostic, prognostic, and therapeutic features
Authors: Rajabally Yusuf A. , Chavada Govindsinh
Published: January 2009

Lewis–Sumner syndrome (L‐SS) represents the asymmetric variant of chronic inflammatory demyelinating polyneuropathy (CIDP). The characteristics and specificities of L‐SS of pure upper‐limb onset, as initially described by Lewis et al. [Multifocal demyelinating neuropathy with persistent conduction block. Neurology 32:958–964, 1982], have not been studied. We describe 8 such patients and review 82 previously reported cases. Distal involvement predominates and is mixed, sensory and motor from onset in only 50% of patients. Pain is a feature in about 20%. Subsequent lower‐limb involvement occurs in <40% of cases. Electrophysiologically, upper‐limb‐onset L‐SS is characterized by the presence of motor conduction blocks in arm nerves in about 90% of cases, and other demyelinating motor abnormalities are significantly less frequent. Cerebrospinal fluid (CSF) protein levels are raised in about 40% of cases and are moderate in most. Mildly raised anti‐GM1 antibody titers are rare (<5%), but very high titers (≥1:6400) have not been reported. Over 80% of treated patients respond, and intravenous immunoglobulins may be more effective than steroids. The prognosis is favorable in 40% of patients who eventually stabilize without treatment. We also reviewed 36 cases of other forms of L‐SS, and present a further 2 cases. The upper‐limb‐onset variant is significantly less likely to spread to other limbs and may be less likely to have raised CSF protein levels. This could reflect a more localized disease process in upper‐limb‐onset L‐SS. This variant may represent a separate entity, to be distinguished from other asymmetric forms of CIDP. © 2009 Wiley Periodicals, Inc. Muscle Nerve 39: 206–220, 2009
Obstructive sleep apnea in patients with inflammatory myopathies
Authors: Selva‐O'Callaghan Albert , Sampol Gabriel , Romero Odile , Lloberes Patricia , Trallero‐Araguás Ernesto , Vilardell‐Tarrés Miquel
Published: January 2009

The purpose of this study was to determine the frequency of obstructive sleep apnea in patients with inflammatory myopathy. An observational and prospective study was performed on a cohort of adult patients with inflammatory myopathy followed at a specialized outpatient clinic. Sixteen consecutive adult patients were evaluated by the Epworth Sleepiness Scale (ESS) and by complete polysomnography study. Disease activity and severity were assessed using the Myositis Disease Activity Assessment Tool (MDAAT) and Myositis Damage Index (MDI), respectively. Associations between sleep parameters and other factors were calculated using the chi‐square test, Fisher's exact test, Mann–Whitney U‐test, and Wilcoxon's test. A serum autoantibody profile was determined for all patients. The mean apnea–hypopnea index was 28.7 (23.8), and 14 patients (87%) had an apnea–hypopnea index >5. The mean frequency of respiratory arousals was 20.1 (12.5). Eleven (68%) patients reported frequently–always snoring, and 3 (19%) had excessive daytime sleepiness (ESS >10). Seven patients were offered continuous positive airway pressure (CPAP) therapy; 4 tolerated the procedure well and reported a clear improvement in daytime sleepiness and/or sleep quality. No significant association was observed between the apnea–hypopnea index and clinical or immunological groups. Dysphagia, disease activity, and disease severity were not significantly associated with any sleep parameters. The frequency of obstructive sleep apnea in adult patients with inflammatory myopathy is high. The possibility that these alterations play a role in persistent fatigue in these patients cannot be ruled out. Muscle Nerve 39: 144–149, 2009
Case of acute motor conduction block neuropathy (AMCBN)
Authors: Manganelli Fiore , Pisciotta Chiara , Iodice Rosa , Calandro Sara , Dubbioso Raffaele , Ranieri Angelo , Santoro Lucio
Published: January 2009

We describe a 21 year‐old man with an acute development of weakness whose clinical and serial electrophysiological findings were atypical for Guillain–Barré syndrome. Electrophysiological data suggested a diagnosis of “acute motor conduction block neuropathy” (AMCBN). The 6 months of disease duration and the electrophysiological follow‐up, which never showed axonal degeneration until complete clinical recovery, raise the issue of the relationship between AMCBN and acute motor axonal neuropathy (AMAN). Muscle Nerve 39: 224–226, 2009
Onset Temperatures in Hot Wire Ignition of AN‐Based Emulsions
Authors: Chan Sek Kwan , Turcotte Richard
Published: January 2009

Hot wire ignition experiments were carried out recently at the Canadian Explosives Research Laboratory on a few emulsion formulations. The data indicate that there is a pressure‐dependent onset temperature beyond which the wire temperature increases at an accelerated rate. In order to explain this observation and to detect this temperature more consistently, particularly at low pressures, the data are reanalysed by comparing the experimental wire temperature with that predicted from theory for the heating of an inert material. For this purpose, an analytical theory from the literature is reviewed and the numerical solution developed in this report is described. The latter can deal with more general solutions with variable thermal properties and chemical reactions in the condensed medium surrounding the wire.
Predicting protein pKa by environment similarity
Authors: Milletti Francesca , Storchi Loriano , Cruciani Gabriele
Published: January 2009

A statistical method to predict protein pKa has been developed by using the 3D structure of a protein and a database of 434 experimental protein pKa values. Each pKa in the database is associated with a fingerprint that describes the chemical environment around an ionizable residue. A computational tool, MoKaBio, has been developed to identify automatically ionizable residues in a protein, generate fingerprints that describe the chemical environment around such residues, and predict pKa from the experimental pKa values in the database by using a similarity metric. The method, which retrieved the pKa of 429 of the 434 ionizable sites in the database correctly, was crossvalidated by leave‐one‐out and yielded root mean square error (RMSE) = 0.95, a result that is superior to that obtained by using the Null Model (RMSE 1.07) and other well‐established protein pKa prediction tools. This novel approach is suitable to rationalize protein pKa by comparing the region around the ionizable site with similar regions whose ionizable site pKa is known. The pKa of residues that have a unique environment not represented in the training set cannot be predicted accurately, however, the method offers the advantage of being trainable to increase its predictive power. Proteins 2009. © 2009 Wiley‐Liss, Inc.
Crystal structure of the Bacillus anthracis nucleoside diphosphate kinase and its characterization reveals an enzyme adapted to perform under stress conditions
Authors: Misra Gauri , Aggarwal Anita , Dube Divya , Zaman Mohd Saif , Singh Yogendra , Ramachandran Ravishankar
Published: January 2009

Nucleoside diphosphate kinases (Ndks) play an important role in a plethora of regulatory and metabolic functions. Inhibition of the B. anthracis Ndk mRNA results in the formation of nonviable aberrant spores. We report the characterization and crystal structure of the enzyme from B. anthracis nucleoside diphosphate kinase (BaNdk), the first from sporulating bacteria. The enzyme, although from a mesophilic source, is active at extremes of pH (3.5–10.5), temperature (10–95°C) and ionic strength (0.25–4.0M NaCl). It exists as a hexamer that is composed of two SDS‐stable trimers interacting in a back‐to‐back association; mutational analysis confirms that the enzyme is a histidine kinase. The high‐resolution crystal structure reported here reveals an unanticipated change in the conformation of residues between 43 and 63 that also regulates substrate entry in other Ndks. A comparative structural analysis involving Ndks from seven mesophiles and three thermophiles has resulted in the delineation of the structure into relatively rigid and flexible regions. The analysis suggests that the larger number of intramolecular hydrogen bonds and to a lesser extent ionic interactions in BaNdk contributes to its high thermostability. Mutational analysis and Molecular Dynamics simulations were used to probe the role of a highly conserved Gly19 (present at the oligomeric interface in most of the Ndks). The results suggest that the mutation leads to a rigidification of those residues that facilitate substrate entry and consequently leads to a large reduction in the kinase activity. Overall, the enzyme characterization helps to understand its apparent adaptation to perform under stress conditions. Proteins 2009. © 2009 Wiley‐Liss, Inc.
A new prediction strategy for long local protein structures using an original description
Authors: Bornot Aurélie , Etchebest Catherine , de Brevern Alexandre G.
Published: January 2009

A relevant and accurate description of three‐dimensional (3D) protein structures can be achieved by characterizing recurrent local structures. In a previous study, we developed a library of 120 3D structural prototypes encompassing all known 11‐residues long local protein structures and ensuring a good quality of structural approximation. A local structure prediction method was also proposed. Here, overlapping properties of local protein structures in global ones are taken into account to characterize frequent local networks. At the same time, we propose a new long local structure prediction strategy which involves the use of evolutionary information coupled with Support Vector Machines (SVMs). Our prediction is evaluated by a stringent geometrical assessment. Every local structure prediction with a Cα RMSD less than 2.5 Å from the true local structure is considered as correct. A global prediction rate of 63.1% is then reached, corresponding to an improvement of 7.7 points compared with the previous strategy. In the same way, the prediction of 88.33% of the 120 structural classes is improved with 8.65% mean gain. 85.33% of proteins have better prediction results with a 9.43% average gain. An analysis of prediction rate per local network also supports the global improvement and gives insights into the potential of our method for predicting super local structures. Moreover, a confidence index for the direct estimation of prediction quality is proposed. Finally, our method is proved to be very competitive with cutting‐edge strategies encompassing three categories of local structure predictions. Proteins 2009. © 2009 Wiley‐Liss, Inc.
Effect of aluminum supply on aluminum‐induced crystallization of amorphous silicon at low temperature
Authors: Song Rui , Liu Yulong , Cao Zexian
Published: January 2009

Effect of aluminum supply on aluminum‐induced crystal‐lization of amorphous silicon was studied in the glass/Al/a‐Si structures of different layer thicknesses prepared by using magnetron sputtering at room temperature. Various characterizing techniques have been applied to evaluate the quality of the resulting poly‐Si layers, including crystallinity, integrity and doping level caused by residual Al atoms. We emphasize the fact that Al atoms driven to the outermost surface by thermodynamical reasons form, besides an overlayer, a depth profile into poly‐Si, thus excessive Al supply both causes a heavy p‐type doping and imperils the surface compactness in subsequent etching procedure. A critical amount of Al is nevertheless required to achieve a satisfying crystallinity of the poly‐Si layer. With an Al‐layer over 200 nm and annealing at 500 °C, compact and well crystallized poly‐Si layers were obtained the grain size of which is only limited by layer thickness – the fingerprint Raman peak shows a full‐width‐at‐half‐maximum as small as 3.69 cm–1. A strategy of sufficient Al supply in conjunction with annealing and short‐time etching twice is found very effective. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GeSi/Si hetero‐nanocrystals and the applications in MOSFET memories
Authors: Shi Yi , Lv Jin , Yang Hongguan , Chen Yubin , Wang Guangli , Wang Zerui , Pu Lin , Zhang Rong , Zheng Youdou
Published: January 2009

Charge storage characteristics of MOSFET memory structure based on GeSi/Si hetero‐nanocrystals (HNCs) are investigated by numerical simulation and experimental measurement. Owing to the advantages of a compound potential well and a higher offset at the valence band, this kind of memory has well hole storage. It is expected to serve as a high‐performance nonvolatile memory operating at room temperature. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐organized regular surface patterning by pulsed laser ablation
Authors: Reif Juergen , Costache Florenta , Varlamova Olga , Jia Guobin , Ratzke Markus
Published: January 2009

The impact of intense ultra short laser pulses on solid surface ‐ as in laser ablation ‐ results in a transient perturbation of the material to a state far from equilibrium. Due to ultrafast relaxation of the transient disorder in a few picoseconds, self‐organized surface patterns occur, with a typical feature size at the order of 100 nm or less, similar as observed in ion sputtering and explained by non‐linear dynamics models. The feature size of these structures is determined by the deposited energy dose, their shape and orientation crucially depends on the state of polarization of the incident light. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Assessment of various LED structure designs for high‐current operation
Authors: Bulashevich K. A. , Ramm M. S. , Karpov S. Yu.
Published: January 2009

Using modelling, we have examined alternative designs of light‐emitting diode (LED) structures, aimed at lowering the non‐equilibrium carrier concentration and, hence, at suppression of Auger recombination in the active regions of the diodes. Both a multi‐quantum‐well (MQW) heterostructure and that with a thick single active layer are compared. The MQW structure is found to be ineffective for improvement of the LED internal quantum efficiency (IQE). In contrast, LEDs with a thick single active layer turn out to be quite promising for high‐current operation. Detailed simulation provides a guideline for further optimization of the LED heterostructures. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reduction of buffer‐related current collapse in field‐plate AlGaN/GaN HEMTs
Authors: Nakajima Atsushi , Itagaki Keiichi , Horio Kazushige
Published: January 2009

Two‐dimensional transient analyses of field‐plate AlGaN/GaN HEMTs are performed in which a deep donor and a deep acceptor are considered in a semi‐insulating buffer layer, and quasi‐pulsed current‐voltage curves are derived from them. It is studied how the existence of field plate affects buffer‐related drain lag, gate lag and current collapse. It is shown that the drain lag is reduced by introducing a field plate, because electron injection into the buffer layer is weakened by it, and the trapping effects are reduced. It is also shown that the current collapse and gate lag are reduced in the field‐plate structure. The dependence on SiN passivation layer thickness is also studied, suggesting that there is an optimum thickness of SiN layer to minimize the buffer‐related current collapse and drain lag in AlGaN/GaN HEMTs. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spatial properties of excitonexciton interactions in GaN observed by four‐wave‐mixing spectroscopy
Authors: Toda Y. , Yamaguchi K. , Ishiguro T. , Hoshino K. , Tadatomo K. , Adachi S.
Published: January 2009

Spatial imaging of spectrally‐resolved four‐wave mixing (SR FWM) was performed on a GaN film grown on c ‐sapphire substrate. The image obtained from the exciton resonances at zero time delay clearly showed some highly localized reductions in their intensities whose spatial profiles can be mapped out with a spatial resolution of ∼20 m.

The image obtained from the evaluation of the quantum beats indicates these reductions correspond to the phase changes between two exciton transitions, reflecting the spatial properties of exciton‐exciton interactions. The line‐localization suggests a contribution of line‐defect to the anomalous interactions (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of the surface potential of GaN:Si
Authors: Köhler Klaus , Maier Markus , Kirste Lutz , Wiegert Joachim , Menner Hanspeter
Published: January 2009

The surface potential of GaN:Si is determined for Si doping from 2.4 × 1017 cm–3 to 2.3 × 1019 cm–3 in layers grown by low pressure metal‐organic vapor‐phase epitaxy. We used the sheet resistance of the samples with different thicknesses measured by eddy current, a nondestructive, contactless method, to determine the depleted region. From the width of the depletion layer, which is dependent on the doping concentration, measured by secondary ion mass spectrometry, we obtained the GaN:Si surface potential on the basis of the depletion approximation. The surface potential decreases with increasing carrier concentration from about 1.6 eV down to 0.2 eV. Based on the behavior of the surface potential with doping we determined the surface state density. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐reflectivity Ag‐based p‐type ohmic contacts for blue light‐emitting diodes
Authors: Kawai Ryosuke , Mori Toshiaki , Ochiai Wataru , Suzuki Atushi , Iwaya Motoaki , Amano Hiroshi , Kamiyama Satoshi , Akasaki Isamu
Published: January 2009

In this paper, we propose a novel p‐contact material, which is an Ag‐Pd‐Cu alloy (APC) with high reflectivity, low specific contact resistance, and high thermal stability. APC is an alloy with 98% Ag, 1% Pd and 1% Cu. The APC contact showed a higher reflectance of 88% at 450 nm, a contact resistance as low as 1.4×10–4 Ω cm2, and better thermal stability than an Ag contact that was annealed at 475 °C for 5 min in N2 ambient. We applied the APC contact to a large blue light‐emitting diode (LED) (1 mm × 1 mm) with an emission peak wavelength of 450 nm. At 200 mA, the output power of the LED with the APC contact is 1.6 times higher than that of the LED with the Ni/Au contact. In addition, a significant reduction of the operating voltage at a given current was realized. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
33 μm free standing thick film vertical structure LED made by laser lift‐off
Authors: Sun Yongjian , Qi Shengli , Chen Zhizhong , Kang Xingning , Zhu Guangmin , Chen Cheng , Li Shitao , Pan Yaobo , Yan Jianfeng , Deng Junjing , Long Hao , Hao Maosheng , Yu Tongjun , Zhang Guoyi
Published: January 2009

The 33 μm thick film vertical structure LEDs without any substrate were fabricated and their free standings were successfully realized by laser lift‐off and HVPE technology. Through the AFM analyses we know that the laser irradiation can causes big damage to the wafer. However, since the 33 μm thick film vertical structure LEDs without any substrate have longer distance between the laser irradiating plane and the quantum well than the the thin film (3‐4 μm) vertical structure LED on Cu or Si substrate, the 33 μm free standing thick film vertical structure LEDs exhibited good electrical and optical characteristics for the less damage on the quantum well caused by the laser lift off process. It has also been proved that the 33 μm thick film vertical structure LEDs without any substrate has lower thermal series resistance than the vertical structure LEDs on 300‐400 μm free standing GaN substrate. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
GaN nano‐pendeo‐epitaxy on Si(111) substrates
Authors: Liu Chaowang , Wang Wang Nang , Denchitcharoen Somyod , Gott Alan , Shields Philip A. , Allsopp Duncan W. E.
Published: January 2009

Nano‐pendeo‐epitaxial GaN films have been grown by metalorganic vapour phase epitaxy on nanocolumns fabricated on thin GaN‐on‐Si(111) templates. Optical and structural performances of the films are improved, crack densities are reduced, and self‐separation of GaN films from the substrates at the nanocolumns has been realized. The success of the nano‐pendeo‐epitaxy of GaN films is attributed to the following three techniques developed in this study: (1) the growth of high quality ultrathin GaN/AlN templates on on Si(111) substrates, (2) the fabrication of uniform nanocolumns across the 2‐inch wafer surface, and (3) the in situ conversion of the exposed silicon surfaces of the fabricated nanocolumns to silicon nitride. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Antidiarrhoeal activity ofHypoxis hemerocallideaFisch. & C. A. Mey. (Hypoxidaceae) Corm (‘African potato’) aqueous extract in rodents
Authors: Ojewole John A. O. , Awe Emmanuel O. , Nyinawumuntu Agatha
Published: January 2009

This study investigated the antidiarrhoeal activity ofHypoxis hemerocallideacorm aqueous extract (APE) on experimentally‐induced diarrhoea, gastrointestinal motility, intestinal transit and enteropooling in rodents.H.hemerocallideacorm aqueous extract (APE, 50–400 mg/kg, p.o.) produced dose‐dependent and significant (p< 0.05–0.01) protection of rats and mice against castor oil‐induced diarrhoea, inhibited intestinal transit and delayed gastric emptying. Like atropine (1 mg/kg, p.o.), APE (50–400 mg/kg, p.o.) produced dose‐dependent and significant (p< 0.05–0.01) antimotility effect, and caused dose‐related inhibition of castor oil‐induced enteropooling in the animals. Like loperamide (10 mg/kg, p.o.), APE (50–400 mg/kg, p.o.) dose‐dependently and significantly (p< 0.05–0.01) delayed the onset of castor oil‐induced diarrhoea, decreased the frequency of defaecation and reduced the severity of diarrhoea in the rodents. Compared with control animals, APE (50–400 mg/kg, p.o.) dose‐dependently and significantly (p< 0.05–0.01) decreased the volume of castor oil‐induced intestinal fluid secretion, and reduced the number, weight and wetness of faecal droppings. APE (50–400 mg/mL) also produced concentration‐related and significant (p< 0.05–0.01) inhibitions of the spontaneous, pendular contractions of the rabbit isolated duodenum, and attenuated acetylcholine (ACh, 0.1–5.0 µg/mL)‐induced contractions of the guinea‐pig isolated ileum. Although the precise mechanism of the antidiarrhoeal activity of APE could not be established, the results of this study indicate that APE possesses antidiarrhoeal activity. This finding supports the use of ‘African potato’ as a natural supplementary remedy for the treatment, management and/or control of diarrhoea in some rural communities of southern Africa. Copyright © 2009 John Wiley & Sons, Ltd.
Germinated Buckwheat extract decreases blood pressure and nitrotyrosine immunoreactivity in aortic endothelial cells in spontaneously hypertensive rats
Authors: Kim Dae Won , Hwang In Koo , Lim Soon Sung , Yoo Ki‐Yeon , Li Hua , Kim Young Sup , Kwon Dae Young , Moon Won Kuk , Kim Dong‐Woo , Won Moo‐Ho
Published: January 2009

Thee present study analysed the quantification of rutin in raw buckwheat extract (RBE) and germinated buckwheat extract (GBE) by high performance liquid chromatography (HPLC), and examined changes in body weight, systolic blood pressure (SBP) and nitrotyrosine (a marker for peroxynitrite formation) immunoreactivity in aortic endothelial cells in spontaneously hypertensive rats (SHRs) and normotensive Wistar‐Kyoto (WKY) rats after treatment with RBE and GBE for 5 weeks. In the HPLC study, RBE and GBE contained a mean content of rutin of 1.52 ± 0.21 and 2.92 ± 0.88 mg/g, respectively. In the 600 mg/kg GBE‐treated group, SBP was lower than that in the 600 mg/kg RBE‐treated group. The treatment with RBE and/or GBE significantly reduced oxidative damage in aortic endothelial cells by lowering nitrotyrosine immunoreactivity. These results suggest that GBE has an antihypertensive effect and may protect arterial endothelial cells from oxidative stress. Copyright © 2009 John Wiley & Sons, Ltd.
Phenolic alkaloids as a new class of antioxidants in Portulaca oleracea
Authors: Yang Zijuan , Liu Cejia , Xiang Lan , Zheng Yinan
Published: January 2009

Antioxidant activities of three phenolic alkaloids, i.e., oleracein A (OA), oleracein B (OB) and oleracein E (OE), isolated from Portulaca oleracea were determined, based on scavenging activity against 1,1‐diphenyl‐ 2‐picryl‐hydrazyl (DPPH) radical and inhibitory effect on hydrogen peroxide‐induced lipid peroxidation in rat brain homogenates. The DPPH radical scavenging activities of these phenolic alkaloids were lower than caffeic acid but higher than ascorbic acid and α‐tocopherol, being in the following order: OB > OA > OE. OE was most potent in preventing formation of malondialdehyde (MDA) with an EC50 value of 73.13 µM, close to that of caffeic acid (72.09 µM). It was demonstrated that phenolic alkaloids served as a new class of antioxidant agents in this plant. Copyright © 2009 John Wiley & Sons, Ltd.
Effect of boldo (Peumus boldus Molina) infusion on lipoperoxidation induced by cisplatin in mice liver
Authors: Fernández J. , Lagos P. , Rivera P. , Zamorano‐Ponce E.
Published: January 2009

Peumus boldus Molina (Monimiaceae), commonly referred to as ‘boldo’, is used in traditional Chilean medicine to treat hepatic and gastrointestinal diseases. Its leaves are rich in antioxidant compounds, principally alkaloids and flavonoids. This study evaluates the protective effect of a complete boldo leaf infusion on lipoperoxidation (MDA determination at 532 nm) induced by cisplatin in mice liver. To determine if the observed effect can be explained by the action of boldine or catechin, each compound was studied separately. The mice were divided into 8 groups (n = 6): (I) not treated; (II) treated with cisplatin 6 mg/Kg b.w.; (III) treated with boldo leaf infusion 5%; (IV) pretreated with boldo leaf infusion 5% and treated with cisplatin 6 mg/Kg b.w.; (V) treated with boldine 50 mg/Kg b.w.; (VI) pretreated with boldine 50 mg/Kg b.w. and treated with cisplatin 6 mg/kg.b.w.; (VII) treated with catechin; and (VIII) pretreated with catechin 50 mg/Kg b.w. and treated with cisplatin 6 mg/Kg b.w. As expected, the treatment with cisplatin significantly increased (p < 0.01) lipoperoxidation in comparison with the non‐treated group. Pretreatment with boldo leaf infusion significantly diminished (p < 0.05) the lipoperoxidation induced by cisplatin with respect to the animals not pretreated with the infusion. The pretreatments with boldine and catechin significantly diminished (p < 0.05) the lipoperoxidation induced by cisplatin with respect to the group treated only with cisplatin. The results suggest that the boldo infusion is acting as a protector with respect to the oxidative hepatic damage caused by cisplatin, and that this protective ability would be due to the presence in the infusion of the natural antioxidants boldine and principally catechin. These findings suggest the potential use of the infusion as a chemoprotector. Copyright © 2009 John Wiley & Sons, Ltd.
Quantitative Structure‐Toxicity Models for Heterogeneous Aliphatic Compounds
Authors: Duchowicz Pablo R. , Ocsachoque Marco A.
Published: January 2009

The presented work deals with the Quantitative Structure–Activity Relationships (QSAR) analysis for the growth inhibition of the ciliated protozoan Tetrahymena pyriformis by a mechanistically diverse set of aliphatic organic compounds. A pool of 1509 theoretical descriptors coding for lipophilic, constitutional, steric, and electronic properties of these molecules is calculated with the Dragon software. The simultaneous linear regression analyses on 370 compounds led to a five‐parameter model characterized by R=0.909 and leave more out Rl‐30%‐o=0.843. An external test set of 100 structurally related derivatives that is not employed during the model development demonstrates that the relationship found shows good predictive power, with Rval=0.881. Finally, the application of this subset of descriptors on the complete set of 470 aliphatic structures outperforms previous reported results. Our study corroborates that hydrophobicity, calculated among more than a thousand of structural variables, represents an important factor for predicting the toxicity of aliphatic compounds.
Enhanced Replacement Method‐based Quantitative Structure–Activity Relationship Modeling and Support Vector Machine Classification of 4‐Anilino‐3‐quinolinecarbonitriles as Src Kinase Inhibitors
Authors: Sun Min , Zheng Youguang , Wei Hongtao , Chen Junqing , Cai Jin , Ji Min
Published: January 2009

Quantitative Structure–Activity Relationship (QSAR) analyses have been carried out for a set of 4‐anilino‐3‐quinolinecarbonitriles. Considering simplicity and interpretability, Src kinase‐inhibiting activity of these compounds expressed in log units have been modeled by Multiple Linear Regression (MLR) analysis combined with various variable selection approaches, including Forward Selection (FS), Genetic Algorithm (GA), Simulated Annealing (SA), and Enhanced Replacement Method (ERM), based on descriptors generated by E‐Dragon software. Performances of these models are rigorously validated by Leave‐One‐Out Cross‐Validation (LOOCV), five‐fold Cross‐Validation (5‐CV), and external validation. The ERM–MLR model is much better than other models, with R2=0.854 and $\rm{ R_{{\rm{pred}}}^{\rm{2}} }$=0.840. Robustness and predictive ability of this model are prudently evaluated. Moreover, another classification analysis using Fisher Linear Discriminant Analysis (FLDA) and Support Vector Machine (SVM) is also developed with the aim of dissecting the most significant factors that lead to the activity difference between highly active compounds and those not so active. The 5‐CV and external validation prediction accuracy reached 95.00 and 93.75% for the SVM‐based model, respectively. The resulting models could act as an efficient strategy for estimating the Src‐inhibiting activity of novel 4‐anilino‐3‐quinolinecarbonitriles and provide some insight into the structural features related to the biological activity of these compounds.
Fragment‐Based QSAR and Molecular Modeling Studies on a Series of Discodermolide Analogs as Microtubule‐Stabilizing Anticancer Agents
Authors: Salum Lívia B. , Dias Luiz C. , Andricopulo Adriano D.
Published: January 2009

Inhibition of microtubule function is an attractive rational approach to anticancer therapy. Although taxanes are the most prominent among the microtubule‐stabilizers, their clinical toxicity, poor pharmacokinetic properties, and resistance have stimulated the search for new antitumor agents having the same mechanism of action. Discodermolide is an example of nontaxane natural product that has the same mechanism of action, demonstrating superior antitumor efficacy and therapeutic index. The extraordinary chemical and biological properties have qualified discodermolide as a lead structure for the design of novel anticancer agents with optimized therapeutic properties. In the present work, we have employed a specialized fragment‐based method to develop robust quantitative structure–activity relationship models for a series of synthetic discodermolide analogs. The generated molecular recognition patterns were combined with three‐dimensional molecular modeling studies as a fundamental step on the path to understanding the molecular basis of drug–receptor interactions within this important series of potent antitumoral agents.
Slope traversal controls for planetary exploration rover on sandy terrain
Authors: Ishigami Genya , Nagatani Keiji , Yoshida Kazuya
Published: January 2009

In this paper, two control approaches are presented for exploration rovers traversing sandy‐sloped terrain. One of the proposed controls is a model‐based feed‐forward control using a characteristic diagram, called athrust‐cornering characteristic diagram. It consists of various characteristic curves of wheel forces for varied wheel slip conditions. An appropriate steering maneuver for slope traversal can be found using the diagram with slope traversal criteria. The other control is a sensor‐based feedback control. A key approach to this feedback control is to compensate for three types of slip, namely, the vehicle sideslip and longitudinal/lateral slips of a wheel. The feedback control calculates both steering and driving maneuvers that can compensate for these slips and also allow the rover to successfully traverse a sandy slope. The performances of these two control approaches are confirmed in slope traversal experiments using a four‐wheeled rover test bed. The proposed controls are verified by quantitative evaluations of distance and orientation errors. Through the experiment, it was found that the two controls have advantages and disadvantages, and the possibility of merging the model‐based control and the sensor‐based control is discussed. © 2009 Wiley Periodicals, Inc.
Privacy‐preserving robust data aggregation in wireless sensor networks
Authors: Conti Mauro , Zhang Lei , Roy Sankardas , Di Pietro Roberto , Jajodia Sushil , Mancini Luigi Vincenzo
Published: January 2009

In‐network data aggregationin wireless sensor networks (WSNs) is a technique aimed at reducing the communication overhead—sensed data are combined into partial results at intermediate nodes during message routing. However, in the above technique, some sensor nodes need to send their individual sensed values to an aggregator node, empowered with the capability to decrypt the received data to perform a partial aggregation. This scenario raises privacy concerns in applications like personal health care and the military surveillance. A few other solutions exist where the data are not disclosed to the aggregator (e.g., using privacy homomorphism (PH)), but these solutions are not robust to node or communication failure.

The contributions of this paper are two‐fold: first, we design a private data aggregation protocol that does not leak individual sensed values during the data aggregation process. In particular, neither the base station (BS) nor the other nodes are able to compromise the privacy of an individual node's sensed value. Second, the proposed protocol is robust to data‐loss; if there is a node‐failure or communication failure, the protocol is still able to compute the aggregate and to report to the base station the number of nodes that participated in the aggregation. To the best of our knowledge, our scheme is the first one that efficiently addresses the above issues all at once. Copyright © 2009 John Wiley & Sons, Ltd.
Mathematical model for constructing passwords from biometrical data
Authors: Balakirsky Vladimir B. , Ghazaryan Anahit R. , Han Vinck A. J.
Published: January 2009

We propose a probabilistic model for constructing passwords on the basis of outcomes of biometrical measurements. An algorithm for the transformation of biometrical data to passwords is given. Performance of the authentication scheme is evaluated by the compression factor, the false acceptance/rejection rates, the probability distribution over the set of passwords, and the probability of a correct guess of the input biometrical data mapped to the known password. An application of the results to the DNA measurements is presented. Copyright © 2009 John Wiley & Sons, Ltd.
Correction
Authors: Giraudeau B. , Ravaud P. , Donner A.
Published: January 2009

‘Sample size calculation for cluster randomized cross‐over trials’ by Giraudeau B, Ravaud P, Donner A (Statist. Med. 2008; 27(27):5578–5585 [Epub ahead of print])

Equation (5) reads

which should read as

Therefore, the inflation factor discussed two lines after should read as $${\{({1+({p_{0}} -1})\rho)-p_{0}\eta \}}$$.