bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrical transport properties of an organic semiconductor on polyaniline doped by boric acid
Authors: Yakuphanoglu Fahrettin , Şenkal B. Filiz
Published: July 2008

The electrical conductivity, thermoelectric power, and dielectric properties of polyaniline doped by boric acid (PANI‐B) have been investigated. The room temperature electrical conductivity of PANI‐B was found to be 1.02 × 10−4 S cm−1. The thermoelectric power factor for the polymer was found to be 0.64 µW m−1 K−2. The optical band gap of the PANI‐B was determined by optical absorption method, and the PANI‐B has a direct optical band gap of 3.71 eV. The alternating charge transport mechanism of the polymer is based on the correlated barrier hopping (CBH) model. The imaginary part of the dielectric modulus for the PANI‐B suggests a temperature dependent dielectric relaxation mechanism. Electrical conductivity and thermoelectric power results indicate that the PANI‐B is an organic semiconductor with thermally activated conduction mechanism. Copyright © 2008 John Wiley & Sons, Ltd.
Current–voltage and capacitance–voltage characteristics of the ITO/polyaniline doped boron trifloride/Al Schottky diode
Authors: Yakuphanoglu Fahrettin , Şenkal B. Filiz
Published: July 2008

The electrical characteristics of the ITO/polyaniline (PANI) doped boron trifloride (BF3)/Al Schottky diode have been investigated by current–voltage (I–V) and capacitance–voltage (C–V) methods. The diode indicates a rectification behavior with the ideality factor of 4.78. An ideality factor higher than unity can result from the interface state and electronic properties of the PANI doped BF3 organic semiconductor. The barrier height of the diode was determined from both I–V and C–V characteristics. The barrier height obtained from the C–V measurements is higher than that obtained from the I–V measurements. At higher forward bias voltages, the space charge‐limited current is the dominant transport mechanism, whereas at reverse bias voltages, the current flow in the ITO/PANIBF3/Al diode is controlled by Schottky emission mechanism. Copyright © 2008 John Wiley & Sons, Ltd.
In utero therapy for fetal thoracic abnormalities
Authors: Wilson R. Douglas
Published: July 2008

Fetal thoracic lung anomalies are rare. The specific diagnosis can be made by utilizing ultrasound, magnetic resonance imaging (MRI), and Doppler studies. Perinatal surveillance is required for large lesions and mediastinal shift regardless of the pathological diagnosis. These can cause physiological changes in the cardiovascular system with resulting hydrops. In utero therapies are variable but with no large randomized trials to compare risks and benefits. In most cases of fetal lung lesions, continued observation with postnatal therapy is the outcome. When fetal hydrops is present or impending, in utero fetal therapy is required to try to reverse that pathological course associated with fetal or neonatal death. Maternal morbidity is increased with the development of MIRROR syndrome following the presence of long‐standing fetal hydrops and possible surgical procedures. Copyright © 2008 John Wiley & Sons, Ltd.
Prenatal and postnatal management of omphalocele
Authors: Mann Stephanie , Blinman Thane A. , Douglas Wilson R.
Published: July 2008

Omphalocele is one of the most common abdominal wall defects seen in the prenatal period. Once this diagnosis is confirmed, it is important to check the fetal karyotype and thoroughly assess the fetus for other malformations. Prenatal management involves serial assessment of fetal growth and prenatal testing to ensure fetal well‐being. Closure of the abdominal wall and replacement of organs into the abdominal cavity can be done directly if the omphalocele is small or in a staged manner if the omphalocele is large. Successful outcomes for these neonates can be optimized with a multidisciplinary team approach to prenatal and postnatal management. Copyright © 2008 John Wiley & Sons, Ltd.
Syndromic associations with congenital anomalies of the fetal thorax and abdomen
Authors: Hurst Jane , Firth Helen V. , Chitty Lyn S.
Published: July 2008

Anomalies of the thorax and abdomen can be found in a number of genetic syndromes. Whilst it may not be possible to make a definitive diagnosis before birth, knowledge of the potential associations can be useful for the prenatal diagnostician when examining the fetus and counselling the parents. In this article, we describe conditions where other features may be detectable using prenatal ultrasound. We describe the features, potential diagnostic aids and prognosis. The tables list other potential features that may be identified. The range of conditions that can occur emphasises the value of genetic input in the management of a fetus with an apparently normal karyotype and multiple anomalies, the need to save material for future molecular analysis and the requirement of a detailed examination after delivery. These are needed in order to make accurate diagnoses and advise parents with regard to recurrence risks and the potential for prenatal diagnosis in future pregnancies. Copyright © 2008 John Wiley & Sons, Ltd.
Prenatal diagnosis, prediction of outcome and in utero therapy of isolated congenital diaphragmatic hernia
Authors: Doné Elisa , Gucciardo Leonardo , Van Mieghem Tim , Jani Jacques , Cannie Mieke , Van Schoubroeck Dominique , Devlieger Roland , Catte Luc De , Klaritsch Philipp , Mayer Steffi , Beck Veronika , Debeer Anne , Gratacos Eduardo , Nicolaides Kypros , Deprest Jan
Published: July 2008

Congenital diaphragmatic hernia (CDH) can be associated with genetic or structural anomalies with poor prognosis. In isolated cases, survival is dependent on the degree of lung hypoplasia and liver position. Cases should be referred in utero to tertiary care centers familiar with this condition both for prediction of outcome as well as timed delivery. The best validated prognostic indicator is the lung area to head circumference ratio. Ultrasound is used to measure the lung area of the index case, which is then expressed as a proportion of what is expected normally (observed/expected LHR). When O/E LHR is < 25% survival chances are < 15%. Prenatal intervention, aiming to stimulate lung growth, can be achieved by temporary fetal endoscopic tracheal occlusion (FETO). A balloon is percutaneously inserted into the trachea at 26–28 weeks, and reversal of occlusion is planned at 34 weeks. Growing experience has demonstrated the feasibility and safety of the technique with a survival rate of about 50%. The lung response to, and outcome after FETO, is dependent on pre‐existing lung size as well gestational age at birth. Early data show that FETO does not increase morbidity in survivors, when compared to historical controls. Several trials are currently under design. Copyright © 2008 John Wiley & Sons, Ltd.
Nitrogen Atmospheric Pressure Post Discharges for Surface Biological Decontamination inside Small Diameter Tubes
Authors: Pointu Anne‐Marie , Ricard André , Odic Emmanuel , Ganciu Mihai
Published: July 2008

A nitrogen afterglow at atmospheric pressure has recently been described as able to transport active species over long distances in small diameter tubes, with a biocidal effect. For a discharge gas composed of nitrogen, either of high purity or with some controlled ppm of oxygen, survival curves are presented. The afterglow, flowing at 40 slm in a cylindrical quartz tube with 8 mm internal diameter is studied using emission spectroscopy. Fundamental or excited states of atomic or molecular species of parent gases are detected and evaluated. Their absolute concentration is measured along the tube axis. Correlated to transport equations, results give information on the creation and destruction reactions of these species, especially of the O(1S) metastable state of O, the species that has been shown to boost the biocidal effect.

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The influence of the solution composition including additives on the structure and composition of electrochemical Ni–B coatings
Authors: Szeptycka B. , Gajewska‐Midzialek A.
Published: July 2008

The structure and internal stresses were investigated for d.c.‐plated Ni composite deposits prepared from a low‐concen‐tration Watts electrolyte, with and without additive agents and dispersive B particles. The dispersed phase and additives used in the bath were shown to affect the composition and structure of the electrodeposited composite layer. An increase in the content of B particles in the coating and in the size of [111] nickel crystallites led to increased roughness of Ni‐B coatings. The microhardness of the deposited Ni‐B layers increased as the size of [111] nickel crystallites decreased. The internal stresses of the deposited composite coatings depended to a large degree on the additive in the bath. Ni‐B coatings had a (100) texture, with texture (111) and (311) also frequently occurring. Orientation (100) developed even more strongly than in coatings deposited without additives. This shows that in the presence of 3‐(1‐pyridinio)‐propanesulfonate inner salt (PPS), the development of (110), (111) and (311) orientation is blocked. When the additives were used together, the dimensions of the [111] nickel crystallites in all coatings decreased to the smallest dimension in any of the studied coatings. The results suggest that as the effect of the organic compounds employed the nanostructure of the nickel matrix was developed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical study of the radiation effect on the flowing of mixed convection along a vertical channel
Authors: Aggoune S. , Amara E. H. , Hamadi F.
Published: July 2008

Radiation effect and mixed convection flow are solved numerically in two‐dimensional vertical channel. The main objective is to study the effect of radiation on the flow using radiation models available in Fluent software. The study is done for a Richardson number (Ri = 2.5). Our results when the radiation is ignored are compared with those of the article: Mixed convection in ducts with asymmetric wall heat fluxes [W. Aung and G. Worku, J. Heat Transfer 109, 947 (1987)]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prospective crystallization of amorphous Si films for new Si TFTs
Authors: Noguchi Takashi
Published: July 2008

Prospective crystallization results of amorphous silicon film are reviewed and are discussed. Silicon TFTs are playing an important role for Active‐Matrix Flat Panel Displays (AM‐FPD) based on amorphous or poly‐Si thin‐film transistors (TFTs). Poly‐Si TFTs provide a possibility to develop highly functional system on pane (SoP) applications. In order to get a high performance TFT, large poly‐crystal grains or high cystallinity for the film is required. Two basic crystallization techniques namely solid phase crystallization (SPC) and excimer laser crystallization (ELC) are reviewed and relating issues are described. A grain growth technique has been developed based on the two crystallization techniques, so far. In order to mount a poly‐Si TFT system on a flexible panel such as a plastic, an excimer laser of UV pulse beam has an advantage for the TFT channel as well as for the source and drain contacts as a ultra‐low temperature poly‐Si (U‐LTPS) process. To realize a high performance TFT of uniform and high carrier mobility, location control crystallization had been proposed. Some of the distinctive results for crystal orientation control of (100) and (111) face using the laser crystallization techniques are described. In the future, single‐crystalline Si TFT of a functional 3D structure is expected to realize an advanced SoP for ubiquitous electronics era. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ultraviolet laser structuring of silicon carbide for cold cathode applications
Authors: Spanakis E. , Dialektos J. , Stratakis E. , Zorba V. , Tzanetakis P. , Fotakis C.
Published: July 2008

We present results of the first attempt to produce arrays of sharp Silicon Carbide (SiC) electron emitters by ultraviolet pulsed‐laser processing of single‐crystal SiC surfaces. This simple one‐step technique, performed under controlled pressure of a reactive gas, has demonstrated efficient silicon cold cathodes both in terms of current density and of emission threshold. SiC has been found to produce the best emitters when treated in air. The corresponding cathodes have a lower emission threshold and produce higher current densities than their Si‐based counterparts. The role of surface morphology on the electron emission properties obtained is discussed in comparison to silicon. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homoepitaxial ZnO thin films by PLD: Structural properties
Authors: Lorenz M. , Wagner G. , Rahm A. , Schmidt H. , Hochmuth H. , Schmid H. , Mader W. , Brandt M. , von Wenckstern H. , Grundmann M.
Published: July 2008

Homoepitaxial ZnO films deposited on annealed hydrothermal O‐face ZnO single crystals show superior structural quality. This is demonstrated by narrow ZnO(00.2) rocking curves with FWHM of typically 23 to 35 arcsec, and nearly dislocation‐free TEM cross sections. Nominally undoped ZnO films indicate a minor in‐plane strain of about 250 ppm and no out‐of‐plane strain. Target doping by 0.01% P2O5 or 0.5% Li3N results in pseudomorphic film growth without in‐plane strain. Increasing doping concentration of 0.1 and 1% P2O5 results in both in‐plane and out‐of‐plane strain up to 0.9% indicating relaxed films. The O‐face polarity of the homoepitaxial ZnO films is confirmed by convergent beam electron diffraction. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of laser crystallization on hydrogen bonding in poly‐Si
Authors: Nickel N. H. , von Maydell K.
Published: July 2008

We investigate the influence of the hydrogen content in the amorphous starting material on hydrogen bonding and defect passivation in laser crystallized poly‐Si using electron‐spin‐resonance and hydrogen effusion measurements. After laser dehydrogenation and crystallization the specimens contain a residual H concentration of 8×1021 cm–3 to 1.5×1022 cm–3. During a vacuum anneal at least 1.5×1021 cm–3 H atoms are mobile in the lattice, however, only about 3.7×1018 cm–3 H atoms passivate Si dangling‐bonds. Our results show that the annealing treatment can cause the vast majority of H atoms to accumulate in H stabilized platelets. Since defect passivation preferentially occurs at grain boundaries and platelet nucleation and growth is confined to the interior of single crystal grains, H equilibration is governed by two spatially separated processes. Moreover, our data demonstrate that the hydrogen density‐of‐states distribution derived from H effusion data is dynamic and changes in response to experimental parameters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pulsed laser annealing of semiconductor structures for functional devices
Authors: Misra N. , Xu L. , Rogers M. S. , Ko S. H. , Grigoropoulos C. P.
Published: July 2008

We review our progress on the laser processing of semiconductor microstructures and nanostructures for functional devices. Fundamental research conducted to understand the melt‐mediated phase transformations induced by nanosecond laser irradiation in thin semiconductor films is presented. A detailed experimental study analyzed the physical mechanisms of the explosive crystallization in amorphous germanium that produces large area self‐sustained crystal growth. The double laser crystallization method that combines a nanosecond laser pulse and a modulated microsecond laser beam was shown to produce ultra‐large grain polycrystalline silicon, enabling fabrication of thin film transistor devices of high performance from amorphous silicon films. The crystal growth process was imaged by temporally resolved photography. Non‐melt Excimer Laser annealing of thin silicon‐on‐insulator films for dopant activation was demonstrated. Applying multiple laser pulses below the melting threshold effected solid phase annealing of the single crystalline silicon films. Semiconductor nanowires are one‐dimensional nanostructures that have displayed the potential to be used with low‐cost flexible plastic substrates for applications such as large‐area displays and sensor arrays. The excimer laser annealing of silicon nanowires is demonstrated as an alternative to conventional thermal annealing for dopant activation. The optical absorption of the nanowires is discussed and the effect of parameters such as fluence and number of pulses is investigated. The interaction of laser pulses with silicon nanowires is investigated through numerical simulations. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excimer laser beam/ITO interaction: from laser processing to surface reaction
Authors: Legeay G. , Castel X. , Benzerga R. , Pinel J.
Published: July 2008

We investigated interactions between UV light and Indium Tin Oxide (ITO) thin films sputtered at room temperature. Owing to their photon energy, higher than the band gap of In2O3 (3.5–4.0 eV), KrF (5.0 eV) or XeCl (4.0 eV) lasers proved useful, at high fluences (1‐3 J/cm2) for minute laser shaping, at low fluences (100 mJ/cm2) for laser annealing, or even at very low fluences for gases desorption. Sputtered ITO becomes totally amorphous when an oxygen flow is mixed in the process argon and adjusted for the lowest resistivity. As non optimised layers behave like gas sensors, amorphous ITO is immune to atmospheric agents. The band structure of indium oxide and exposures to UV light at selected wavelengths helped to a better understanding of the gas sensing mechanisms on oxygen rich and oxygen poor layers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fixed charge density distribution on pulsed laser deposited high‐k oxide layers
Authors: Ratzke M. , Yang B. , Reif J.
Published: July 2008

We report on Scanning Kelvin Probe Microscopy of thin praseodymium oxide layers produced by pulsed laser deposition on silicon substrates. These measurements allow an almost direct quantification of the charge state of both interface and bulk of the films. Surprisingly, we find an apparent change in the charge distribution as a result of exposing the structure to ambient air: Immediately after deposition, negative charges are trapped at the interface between film and silicon substrate, and positive charges in the film bulk. After exposure to ambient air for about a week, a dramatic change of surface potentials is observed, including the sign of the charges.

Whereas the influence of growth related parameters like film thickness on the surface potential by can be easily investigated, the role of ageing under ambient conditions is, presently, by far not understood. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multicrystalline silicon films with large grains on glass: preparation and applications
Authors: Andrä Gudrun , Falk Fritz
Published: July 2008

Polycrystalline silicon films on glass with grain sizes exceeding 10 µm by far are of growing interest for thin film solar cells as well as for TFTs in flat panel displays. Grains as large as this arise preferably from solidification of the melt. The most successful method for preparing such films is laser melting and crystallization of amorphous silicon, which may be deposited at temperatures well below the softening point of glass substrates. By making use of a laser the silicon melting time can be short enough as not to damage the substrate. Moreover, by using an appropriate laser irradiation process, a temperature regime can be chosen so as to influence the nucleation rate and growth kinetics to get grain sizes over 100 µm in size. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low frequency noise in polysilicon thin film transistors: effect of the laser annealing of the active layer
Authors: Pichon L. , Boukhenoufa A. , Cordier C.
Published: July 2008

Low‐frequency noise is studied in N‐channel polysilicon TFTs issued from two (low temperature ≤600 °C) technologies: furnace solid phase crystallized (FSPC) and laser solid phase crystallized (LSPC) TFTs. The distribution of the trap states (DOS) into the polysilicon bandgap determined for devices biased in the weak inversion is one decade lower for LSPC devices. The high range values (10–4 ≤ α ≤ 1) of the measured macroscopic noise parameter, defined according to the Hooge empirical relationship, are explained by the drain current crowding due to structural defects within the active layer. The higher values of α for the LSPC TFTs are attributed to a better structural quality of the active layer. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Laser‐induced self organization of silicon–germanium hillocks for field emission displays
Authors: Weizman M. , Nickel N. H. , Sieber I. , Yan B. , Fostiropoulos K.
Published: July 2008

We report here on the formation of a self‐organized hillock structure in polycrystalline silicon–germanium (SiGe) thin films with a Ge content of 30 to 70%, due to the irradiation of the films with a sequence of laser pulses. By varying the crystallization parameters it is possible to control the periodicity length of the structure from 0.4 to 2 µm. The self organization phenomenon can be switched on and off by using substrates with different thermal conductivities. In addition, we show that the self‐organized hillock structure exhibits a low field emission threshold of 20 V/µm and therefore has an immense potential for field emission displays. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
KTa0.5Nb0.5O3ferroelectric thin films grown by pulsed laser deposition: structural characteristics and applications to microwave devices
Authors: Moussavou A.‐G. , Députier S. , Perrin A. , Sauleau R. , Castel X. , Legeay G. , Benzerga R. , Mahdjoubi K. , Guilloux‐Viry M.
Published: July 2008

In this paper, we report on KTN ferroelectric thin films grown by Pulsed Laser Deposition on various substrates suitable for microwave applications and the agility of CPW stub resonators operating in X‐band printed on these films. The ferroelectric material selected here is KTa0.5Nb0.5O3(KTN). X‐ray characterizations and scanning electron microscopy re‐ vealed an epitaxial growth on MgO and LaAlO3substrates, while films deposited on sapphire were textured. Measurements have demonstrated a tunability reaching 5% for KTN/sapphire and 1% for KTN/MgO‐LaAlO3. The resonators have also been characterized in terms of quality factor. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pulsed laser deposition with excimer lasers
Authors: Delmdahl R. , Pätzel R.
Published: July 2008

Progress in material research and processing industry is fueled by the technique of pulsed laser deposition (PLD). High energy excimer lasers enable this technique since every material is amenable to their high photon energies. Spectral properties, temporal pulse and laser beam parameters of state of the art excimer lasers will be compared with frequency converted Nd:YAG lasers. Both quality and longevity of the deposited layers strongly depend on the degree of accuracy achieved in the thin film ablation and subsequent deposition process. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excimer‐laser induced structural transformations of TiO2 thin films
Authors: Van Overschelde O. , Boisdequin J. M. , Leclère Ph. , Wautelet M.
Published: July 2008

Thin films of TiO2 are deposited by magnetron sputtering on glass substrate and are irradiated by UV radiation using a KrF excimer laser (λ = 248 nm). The present works deals with the ablation regime. In order to characterize the structural transformations occurring in the process, the morphology of the films are studied as a function of the laser fluence (F), by means of profilometry and atomic force microscopy (AFM). As deposited films are measured to be amorphous. After one pulse, when the laser fluence, F, is varied, various regimes are observed. We show thanks to this process, it is possible to remove a layer in a predefined thickness by choosing F. More over, we observe a linear dependence of the ablated depth with F. It is shown that the morphology of the surfaces depends strongly of F, as evidenced from AFM images, roughness measurements and the fractal dimension. In order to interpret these results, temperature evaluations are performed. The ablation rate may not be explained by purely thermal effects. It is argued that electronic effects play a major role in excimer‐laser induced structural transformations of TiO2 thin films. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pulsed‐laser deposition of ZnO thin‐films on MgO substrates
Authors: Friedrich F. , Sieber I. , Klaus M. , Genzel Ch. , Nickel N. H.
Published: July 2008

Zinc oxide thin‐films were grown by laser deposition technique on (111)‐ and (100)‐oriented magnesium oxide substrates (MgO). The deposition temperature was varied between 600 and 860 °C. In this temperature range the formation of Mg(OH)2 is thermodynamically unfavorable which prevents a degradation of the MgO surface. The films were characterized by scanning electron microscopy, Raman spectroscopy, and X‐ray diffraction. The results show that high‐quality c‐axis oriented ZnO thin‐films were grown on (111)‐oriented MgO. On (100)‐oriented MgO a more complex ZnO thin‐film formation was observed. At lower growth temperatures grains of different orientation were identified. Grains with orientations that deviated from (001) contain more residual stress, which manifests itself in a shift of the E2high phonon mode position to 442 cm–1. With increasing growth temperature the film structure becomes more uniform and at 860 °C large areas of either (001) or (101) orientation were found. The results also indicate that no amorphous ZnO buffer layer is formed at the interface. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of composition and structure of ferroelectric oxide thin films grown by pulsed laser deposition
Authors: Guilloux‐Viry Maryline , Peng Wei , Députier Stéphanie , Bouquet Valérie , Perrin André
Published: July 2008

SrBi2Nb2O9 and KTa1–xNbxO3 high quality thin films were grown by pulsed laser deposition. An accurate optimization of deposition conditions is a prerequisite for the control of composition, mainly according to the high volatility of Bi and K. In order to take benefit of the ferroelectric characteristics for new microelectronic devices, thin films were epitaxially grown on various substrates and seed layers adapted to application requirements. For that purpose metal electrodes and ferroelectric oxides were associated in a planar capacitor geometry or in a coplanar configuration depending on the targeted applications. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Temperature and moist‐stability effects on midlatitude orographic precipitation
Authors: Kirshbaum Daniel J. , Smith Ronald B.
Published: July 2008

Idealized, convection‐resolving simulations of moist orographic flows are conducted to investigate the influence of temperature and moist stability on the drying ratio (DR), defined as the fraction of the impinging water mass removed as orographic precipitation. In flow past a long ridge, where most of the air rises over the barrier rather than detouring around it, DR decreases as the surface temperature (Ts) increases, even as the orographic cap cloud becomes statically unstable at higher Ts and develops embedded convection. This behaviour is explained by a few physical principles: (1) the Clausius–Clapeyron equation dictates that the normalized condensation rate decreases as the flow gets warmer, (2) the replacement of ice‐phase precipitation growth with warm‐rain processes decreases the efficiency by which condensate is converted to precipitation, thereby lowering precipitation efficiency, and (3) embedded convection acts more to vertically redistribute moisture than to enhance precipitation. Over an isolated mountain, the effects of (1) and (2) are counteracted by moisture deflection around the barrier, which is stronger in the colder, more stable flows. Copyright © 2008 Royal Meteorological Society
Quantification of key red blood cell folates from subjects with defined MTHFR 677C>T genotypes using stable isotope dilution liquid chromatography/mass spectrometry
Authors: Huang Yuehua , Khartulyari Stefanie , Morales Megan E. , Stanislawska‐Sachadyn Anna , Von Feldt Joan M. , Whitehead Alexander S. , Blair Ian A.
Published: July 2008

Red blood cell (RBC) folate levels are established at the time of erythropoiesis and therefore provide a surrogate biomarker for the average folate status of an individual over the preceding four months. Folates are present as folylpolyglutamates, highly polar molecules that cannot be secreted from the RBCs, and must be converted into their monoglutamate forms prior to analysis. This was accomplished using an individual's plasma pteroylpolyglutamate hydrolase by lysing the RBCs in whole blood at pH 5 in the presence of ascorbic acid. Quantitative conversion of formylated tetrahydrofolate derivatives into the stable 5,10‐methenyltetrahydrofolate (5,10‐MTHF) form was conducted at pH 1.5 in the presence of [13C5]‐5‐formyltetrahydrofolate. The resulting [13C5]‐5,10‐MTHF was then used as an internal standard for the formylated forms of tetrahydrofolate that had been converted into 5,10‐MTHF as well any 5,10‐MTHF that had been present in the original sample. A stable isotope dilution liquid chromatography‐multiple reaction monitoring/mass spectrometry method was validated and then used for the accurate and precise quantification of RBC folic acid, 5‐methyltetrahydrofolate (5‐MTHF), tetrahydrofolate (THF), and 5,10‐MTHF. The method was sensitive and robust and was used to assess the relationship between different methylenetetrahydrofolate reductase (MTHFR) 677C>T genotypes and RBC folate phenotypes. Four distinct RBC folate phenotypes could be identified. These were classified according to the relative amounts of individual RBC folates as type I (5‐MTHF >95%; THF <5%; 5,10‐MTHF <5%), type II (5‐MTHF <95%; THF 5% to 20%; 5,10‐MTHF <5%), type III (5‐MTHF >55%; THF >20%; 5,10‐MTHF >5%), and type IV (5‐MTHF <55%; THF >20%; 5,10‐MTHF >5%). Copyright © 2008 John Wiley & Sons, Ltd.
Structural characterization and identification of ecdysteroids from Sida rhombifolia L. in positive electrospray ionization by tandem mass spectrometry
Authors: Wang Yan‐Hong , Avula Bharathi , Jadhav Atul N. , Smillie Troy J. , Khan Ikhlas A.
Published: July 2008

Seven ecdysteroids isolated from Sida rhombifolia L. were studied by electrospray ionization multi‐stage tandem mass spectrometry (ESI‐MSn) in the positive ion mode using an ion trap analyzer and high‐performance liquid chromatography coupled with a diode‐array detector (HPLC/DAD). The HPLC experiments were performed by means of a reversed‐phase C18 column and a binary mobile phase system consisting of water (containing 0.05% formic acid) and acetonitrile (containing 0.05% formic acid) under gradient elution conditions. According to mass spectral features and the substitution at C‐2, C‐20, C‐24 and C‐25, ecdysteroids in S. rhombifolia were classified into three sub‐groups. Structural identification of these three sub‐groups of ecdysteroids was established by LC/multi‐stage ion trap mass spectrometry on‐line or off‐line. The fragmentation patterns of ecdysteroids yielded ions of successive loss of 1–4 water molecules. Furthermore, ions corresponding to the complete loss of the side chain at C‐17 will help to identify the sub‐groups of ecdysteroids in addition to containing a hydroxyl moiety at one of the above‐mentioned positions. Based on the HPLC retention behavior, the diagnostic UV spectra and the molecular structural information provided by ESI‐MSn spectra, a total of nine naturally occurring ecdysteroids were identified, of these two are identified for the first time in S. rhombifolia. Copyright © 2008 John Wiley & Sons, Ltd.
Hydrogen/deuterium exchange on protein solutions containing nucleic acids: utility of protamine sulfate
Authors: Poliakov Anton , Jardine Paul , Prevelige Peter E.
Published: July 2008

Obtaining global hydrogen/deuterium (H/D) exchange data on proteins is an important first step in amide proton exchange experiments. Important information such as the mode of exchange, the cooperativity of folding/unfolding reactions, and the effects of ligand binding can be readily obtained in global exchange experiments. Many interesting biological systems are complexes containing both proteins and nucleic acids. The low pH conditions required to quench H/D exchange reactions result in the formation of stable protein/nucleic acid precipitates which interfere with the liquid chromatography step of the experiment and preclude obtaining mass spectrometric data. In this work we show that the precipitation of proteins and nucleic acids is electrostatic in nature and can be prevented by high ionic strength and by removing nucleic acids by protamine sulfate. Using protamine sulfate in quenching solution, we were able to obtain global H/D data with protein samples containing large amounts of DNA or RNA. Copyright © 2008 John Wiley & Sons, Ltd.
Investigation of norflurazon pesticide photodegradation using plasma desorption time‐of‐flight mass spectrometry analysis
Authors: Thomas J.‐P. , Bejjani A. , Nsouli B. , Gardon A. , Chovelon J.‐M.
Published: July 2008

We have previously demonstrated that PD‐TOFMS (plasma desorption time‐of‐flight mass spectrometry) analysis is a powerful technique for the in situ analysis of pesticides deposited or adsorbed on solid materials. With the aim of producing reproducible data on the modification of a pesticide under controlled photodegradation conditions, we have now undertaken a study where both the substrate and the pesticide are well characterized. This is the case for norflurazon deposited onto an aluminium substrate, in particular regarding the reproducibility of preparation of the samples and the change with time of their chemical composition. Degradation parameters have been derived from the variation in yield of ions representative of the molecule and of its breakdown products and, particularly, from the time required for 50% dissipation of their initial concentration (DT50). DT50 values ranging between 1 and 10 h have been found. An interpretation of the degradation process is proposed from the decay of other ions. As expected, the degradation is faster when the UV sunlight is unfiltered (a factor of 3.8 for the molecule, and around 5 for the breakdown products). Copyright © 2008 John Wiley & Sons, Ltd.
Metabonomics investigation of human urine after ingestion of green tea with gas chromatography/mass spectrometry, liquid chromatography/mass spectrometry and 1H NMR spectroscopy
Authors: Law Wai Siang , Huang Pei Yun , Ong Eng Shi , Ong Choon Nam , Li Sam Fong Yau , Pasikanti Kishore Kumar , Chan Eric Chun Yong
Published: July 2008

A method using gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS) and 1H NMR with pattern recognition tools such as principle components analysis (PCA) was used to study the human urinary metabolic profiles after the intake of green tea. From the normalized peak areas obtained from GC/MS and LC/MS and peak heights from 1H NMR, statistical analyses were used in the identification of potential biomarkers. Metabolic profiling by GC/MS provided a different set of quantitative signatures of metabolites that can be used to characterize the molecular changes in human urine samples. A comparison of normalized metabonomics data for selected metabolites in human urine samples in the presence of potential overlapping peaks after tea ingestion from LC/MS and 1H NMR showed the reliability of the current approach and method of normalization. The close agreements of LC/MS with 1H NMR data showed that the effects of ion suppression in LC/MS for early eluting metabolites were not significant. Concurrently, the specificity of detecting the stated metabolites by 1H NMR and LC/MS was demonstrated. Our data showed that a number of metabolites involved in glucose metabolism, citric acid cycle and amino acid metabolism were affected immediately after the intake of green tea. The proposed approach provided a more comprehensive picture of the metabolic changes after intake of green tea in human urine. The multiple analytical approach together with pattern recognition tools is a useful platform to study metabolic profiles after ingestion of botanicals and medicinal plants. Copyright © 2008 John Wiley & Sons, Ltd.
Quantitative analyses of fullerene and polycyclic aromatic hydrocarbon mixtures via solvent‐free matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Cristadoro Anna , Räder Hans Joachim , Müllen Klaus
Published: July 2008

We explore the feasibility of reliable quantitative matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) analyses via solvent‐free sample preparation, as this procedure provides the unique convenience of being applicable also to insoluble samples. As quantitative MALDI measurements are even more complicated for species ionized by cation attachment, we investigated model systems, such as polycyclic aromatic hydrocarbons (PAHs) and fullerenes, which undergo photoionization and do not require additional cationizing salts. Our quantitative approach rests upon applying the standard‐addition method in MALDI for the quantitative characterization of binary mixtures. Two different systems are tested. Set 1 is composed of hexakis(dodecyl)hexabenzocoronene and hexakis(dodecyl)hexaphenylbenzene, which represent the product and precursor of a cyclodehydrogenation reaction, and Set 2 is a mixture of C60 and C70 fullerenes. In Set 1, severe anomalies could be detected due to a strong influence of the matrix/analyte ratio on the correlation between signal intensity and analyte amount. This can be related to the strong intermolecular interactions among the hexabenzocoronene (HBC) aromatic cores hampering the desorption step and to intermolecular charge transfers, which influence the ionization probability. Minor interferences to the quantitative MALDI characterization are encountered in the analysis of C60 and C70 fullerenes. The spherical shapes of C60 and C70 buckyballs prevent strong aggregation. Thus, no molecule‐dependent anomalies in their desorption‐photoionization behaviour are recognized. Copyright © 2008 John Wiley & Sons, Ltd.
Eigenvalues of Euclidean random matrices
Authors: Bordenave Charles
Published: July 2008

We study the spectral measure of large Euclidean random matrices. The entries of these matrices are determined by the relative position of n random points in a compact set Ωn of ℝd. Under various assumptions, we establish the almost sure convergence of the limiting spectral measure as the number of points goes to infinity. The moments of the limiting distribution are computed, and we prove that the limit of this limiting distribution as the density of points goes to infinity has a nice expression. We apply our results to the adjacency matrix of the geometric graph. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Integrating testing with reliability
Authors: Schneidewind Norman
Published: July 2008

The activities of software testing and reliability are integrated for the purpose of demonstrating how the two activities interact in achieving testing efficiency and the reliability resulting from these tests. Integrating means modeling the execution of a variety of tests on a directed graph representation of an example program. A complexity metric is used to construct the nodes, edges, and paths of the example program. Models are developed to represent the efficiency and achieved reliability of black box and white box tests. Evaluations are made of path, independent path, node, program construct, and random tests to ascertain which, if any, is superior with respect to efficiency and reliability. Overall, path testing has the edge in test efficiency. The results depend on the nature of the directed graph in relation to the type of test. Although there is no dominant method, in most cases the tests that provide detailed coverage are better. For example, path testing discovers more faults than independent path testing. Predictions are made of the reliability and fault correction that results from implementing various test strategies. It is believed that these methods can be used by researchers and practitioners to evaluate the efficiency and reliability of other programs. Copyright © 2008 John Wiley & Sons, Ltd.
Detrusor wall thickness as a test for detrusor overactivity in women
Authors: Lekskulchai O. , Dietz H. P.
Published: July 2008

Objective

The measurement of detrusor wall thickness has been used as a screening test for detrusor overactivity and bladder outlet obstruction in men and women. The aim of this study was to determine, using receiver–operating characteristics (ROC) analysis, the diagnostic value of detrusor wall thickness in predicting detrusor overactivity in women.

Methods

The records of 686 women who attended a tertiary urodynamics service from November 2002 to January 2006 were retrospectively reviewed. The patients had undergone an interview, clinical examination, multichannel urodynamic studies and translabial ultrasound examination. Detrusor wall thickness measurements were taken at the bladder dome, after bladder emptying. ROC analysis was used to identify the optimal cut‐off of detrusor wall thickness in predicting detrusor overactivity.

Results

Average detrusor wall thickness in the detrusor overactivity group was 4.7 ± 1.9 mm (mean ± SD), compared to 4.1 ± 1.6 mm in the non‐detrusor overactivity group (P < 0.001). Using a cut‐off of detrusor wall thickness of 5.0 mm gave a sensitivity of 37% and a specificity of 79% for diagnosing detrusor overactivity. The ROC analysis revealed an area under the curve (AUC) of 0.606 (95% CI, 0.56–0.65).

Conclusions

There is a statistically significant association between detrusor wall thickness and detrusor overactivity (P < 0.001). However, ROC analysis demonstrated that detrusor wall thickness as measured by translabial ultrasound is of little use as a diagnostic test for detrusor overactivity, giving an AUC of only 0.606. Measurement of detrusor wall thickness should therefore not be used as a diagnostic parameter for detrusor overactivity in women. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Heart stroke volume and cardiac output by four‐dimensional ultrasound in normal fetuses
Authors: Molina F. S. , Faro C. , Sotiriadis A. , Dagklis T. , Nicolaides K. H.
Published: July 2008

Objective

To establish reference intervals for fetal heart stroke volume and cardiac output with gestation.

Methods

Fetal heart ventricular volumes were measured using the four‐dimensional (4D) spatiotemporal imaging correlation (STIC) ultrasound technique in 140 normal singleton pregnancies at 12–34 weeks' gestation. The Virtual Organ Computer‐aided AnaLysis (VOCAL) technique was used to obtain a sequence of six sections of each ventricular volume in systole and diastole. Each volume was obtained after a 30° rotation from the previous one around a fixed axis extending from the apex of the heart to the point that divides symmetrically each atrioventricular valve. The contour of each ventricle was drawn manually and the 4D volumes of the left and right ventricle in systole and diastole were estimated. The stroke volume for each ventricle was then calculated by subtracting the one in systole from the one in diastole and the cardiac output was calculated by multiplying the stroke volume by the fetal heart rate. In 50 cases the stroke volumes were measured by the same sonographer twice and the intraobserver agreement of measurements was calculated.

Results

The left and right stroke volume and cardiac output increased exponentially with gestation, from respective mean values of 0.02 mL, 0.01 mL, 2.39 mL/min and 1.80 mL/min at 12 weeks to 0.30 mL, 0.32 mL, 43.46 mL/min and 46.72 mL/min at 20 weeks, and 2.07 mL, 2.67 mL, 284.71 mL/min and 365.99 mL/min at 34 weeks. The ratio of right to left stroke volume increased significantly with gestation from about 0.97 at 12 weeks to 1.13 at 34 weeks. In the Bland–Altman test, the mean percentage difference and 95% limits of intraobserver agreement for left stroke volume and right stroke volume were − 2.1 (−18.4, 14.2)% and − 0.8 (−16.4, 18.0)%, respectively.

Conclusions

In normal fetuses the stroke volume and cardiac output increase between 12 and 34 weeks' gestation. The extent to which, in pathological pregnancies, possible deviations in these measurements from normal prove to be useful in the prediction of outcome remains to be determined. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal ultrasonographic diagnosis of persistent hyperplastic primary vitreous
Authors: Katorza E. , Rosner M. , Zalel Y. , Gilboa Y. , Achiron R.
Published: July 2008

Persistent hyperplastic primary vitreous (PHPV) is a rare developmental malformation of the eye characterized by the presence of a vascular membrane located behind the lens. We report, for the first time in the literature, the identification on ultrasound examination of bilateral cataract and thickened hyaloid artery–lens junction, leading to a diagnosis of bilateral PHPV, in a fetus at 23 weeks' gestation. Histological examination at postmortem confirmed the prenatal diagnosis of bilateral PHPV and cataract. A thorough ultrasound examination of the fetal eye in cases with cataract is recommended. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Progression of Doppler abnormalities in intrauterine growth restriction
Authors: Turan O. M. , Turan S. , Gungor S. , Berg C. , Moyano D. , Gembruch U. , Nicolaides K. H. , Harman C. R. , Baschat A. A.
Published: July 2008

Objective

To identify the sequence of progression of arterial and venous Doppler abnormalities from the onset of placental insufficiency in intrauterine growth restriction (IUGR).

Methods

Prospective observational study of singletons with IUGR (abdominal circumference < 5th percentile) who underwent serial standardized umbilical artery (UA), middle cerebral artery (MCA), ductus venosus (DV) and umbilical vein (UV) Doppler surveillance. Time intervals between progressive Doppler abnormalities and patterns of deterioration were related to UA Doppler status and gestational age.

Results

Six hundred and sixty‐eight longitudinal examinations were performed in 104 fetuses, identifying three patterns of progression: (1) Mild placental dysfunction (n = 34) that remained confined to the UA/MCA. The UA became abnormal at a median of 32 weeks' gestation but the pulsatility index never exceeded 3 SD above normal. Progression took a median of 33 days, requiring delivery at a median of 35 weeks. (2) Progressive placental dysfunction (n = 49). Initially normal UA Doppler PI at 29 weeks' gestation increased beyond 3 SD, progressing to abnormal MCA, absent/reversed UA diastolic flow, abnormal DV, UV pulsations in 9‐day intervals requiring delivery by 33 weeks. (3) Severe early‐onset placental dysfunction (n = 21). Markedly elevated UA PI established by 27 weeks' gestation was associated with rapid (7‐day intervals) progression to abnormal venous Doppler with median delivery at 30.6 weeks. Gestational age at onset, time to delivery and progression intervals were different between patterns (all P < 0.05).

Conclusion

The characteristics of cardiovascular manifestations in IUGR are determined by the gestational age at onset and the severity of placental disease. Recognition of these factors is critical for planning fetal surveillance in IUGR. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.