bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of cell structure and density on the properties of high performance polyimide foams
Authors: Williams Martha K. , Weiser Erik S. , Fesmire James E. , Grimsley Brian W. , Smith Trent M. , Brenner James R. , Nelson Gordon L.
Published: January 2005

Activity at the NASA Langley Research Center (LaRC) has focused on developing low density polyimide foam and foam structures which are made using monomeric solutions or salt solutions formed from the reaction of a dianhydride and diamine dissolved in a mixture of foaming agents and alkyl alcohol at room temperature. Monomer blends may be used to make a variety of polyimide foams with varying properties. The first foaming process developed consisted of thermal cycling the polymer precursor residuum and allowing the inflation of the particles to interact to create the foam. This process has resulted in foam structures with higher percentages of open cell content. Another innovative foaming process has been developed that begins with partially inflated microspheres, “friable balloons”, with incomplete polymer molecular weight gain, which when fully cured into a foam results in more closed cell structures.

In a research study performed by NASA Kennedy Space Center (KSC) and LaRC, two closely related polyimide foams, TEEK‐H series and TEEK‐L series, (4,4′‐oxydiphthalic anhydride/3,4′‐oxydianiline and 3,3′,4,4′‐benzophenonetetracarboxylic acid dianhydride/4,4′‐oxydianiline) were investigated for density effects and closed versus open cell effects on the thermal, mechanical, and flammability properties. Thermal conductivity data under the full range of vacuum pressures indicate that these materials are effective insulators under cryogenic conditions. Contributing factors such as cell content, density, and surface area were studied to determine the effects on thermal conductivity. Cone calorimetry data indicated decreased peak heat release rates for the closed cell system, TEEK‐H friable balloons, compared to the TEEK foams with higher open cell content. Mechanical properties including tensile strength and compressive strength indicated that the materials have good structural integrity. Foams with more open cell content resulted in greater tensile and compressive strengths than the closed cell foams. The maximum closed cell content achieved in the “friable balloon” system was 78% at a foam density of 0.048 gm/cm3. Published in 2005 by John Wiley & Sons, Ltd.
Introduction
Authors: Casida John E , Quistad Gary B
Published: January 2005

© 2001 Society of Chemical Industry
Influence of N‐terminal residue stereochemistry on the prolyl amide geometry and the conformation of 5‐tert‐butylproline type VI β‐turn mimics
Authors: Halab Liliane , Lubell* William D.
Published: January 2005

The effects of N‐terminal amino acid stereochemistry on prolyl amide geometry and peptide turn conformation were investigated by coupling both 𝓁‐ and 𝒹‐amino acids to (2S, 5R)‐5‐tert‐butylproline and 𝓁‐proline to generate, respectively, N‐(acetyl)dipeptide N′‐methylamides 1 and 2. Prolyl amide cis‐ and trans‐isomers were, respectively, favored for peptides 1 and 2 as observed by proton NMR spectroscopy in water, DMSO and chloroform. The influence of solvent composition on amide proton chemical shift indicated an intramolecular hydrogen bond between the N′‐methylamide proton and the acetamide carbonyl for the major conformer of dipeptides (S)‐1, that became less favorable in (R)‐1 and 2. The coupling constant (3JNH,α) values for the cis‐isomer of (R)‐1 indicated a ϕ2 dihedral angle value characteristic of a type VIb β‐turn conformation in solution. X‐ray crystallographic analysis of N‐acetyl‐𝒹‐leucyl‐5‐tert‐butylproline N′‐methylamide (R)‐1b showed the prolyl residue in a type VIb β‐turn geometry possessing an amide cis‐isomer and ψ3‐dihedral angle having a value of 157°, which precluded an intramolecular hydrogen bond. Intermolecular hydrogen bonding between the leucyl residues of two turn structures within the unit cell positioned the N‐terminal residue in a geometry where their ϕ2 and ψ2 dihedral angle values were not characteristic of an ideal type VIb turn. The circular dichroism spectra of tert‐butylprolyl peptides (S)‐ and (R)‐1b were found not to be influenced by changes in solvent composition from water to acetonitrile. The type B spectrum exhibited by (S)‐1b has been previously assigned to a type VIa β‐turn conformation [Halab L, Lubell WD. J. Org. Chem. 1999; 64: 3312–3321]. The type C spectrum exhibited by the (R)‐1b has previously been associated with type II′ β‐turn and α‐helical conformations in solution and appears now to be also characteristic for a type VIb geometry. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
An alternative sampling algorithm for use in liquid chromatography/tandem mass spectrometry experiments
Authors: Kohli Bernhard M. , Eng Jimmy K. , Nitsch Roger M. , Konietzko Uwe
Published: January 2005

In liquid chromatography/tandem mass spectrometry (LC/MS/MS) analyses of complex peptide mixtures, dynamic exclusion functions are used to minimize repeat selections of identical precursors for collision induced dissociation (CID). We describe a new algorithm for the dynamic exclusion of m/z values during LC/MS/MS. Full‐scan based peak exclusion (Fulspec) uses a simplified model of chromatographic peak formation to detect and exclude contaminants present throughout the run or that lead to broad peaks. Therefore, instead of excluding peptides from fragment analysis according to a rigidly predefined time window, the chromatographic properties of the detected analytes are used. The algorithm was tested on two datasets derived from previously published experiments. Fulspec achieves a distribution of CID spectra with minimal tailing on the retention time axis, without resorting to rigid exclusion of m/z values. The procedure further excludes intensities with a bias towards low‐quality CID spectra. This combination frees up valuable analytical capacity. The underlying intensity vs. quality analyses challenge the assumption that abundant precursors automatically give the best identifications. Further validation of the algorithm will require its incorporation by equipment manufacturers into the instrument control programs. Copyright © 2005 John Wiley & Sons, Ltd.
Characterization of microcystins using in‐source collision‐induced dissociation
Authors: Kubwabo Cariton , Vais Natalia , Benoit Frank M.
Published: January 2005

The efficiency of the in‐source collision‐induced dissociation (in‐source CID) technique for the structural characterization of microcystins (MCYSTs) was evaluated. Microcystins that did not contain arginine underwent facile fragmentation to produce characteristic product ions at relatively low cone voltage and could be fully characterized based on their mass spectra. On the other hand, cyclic peptides possessing arginine residues, such as MCYST‐RR, ‐LR, ‐YR and nodularin, were considerably more stable under in‐source CID conditions and required higher cone voltage to induce fragmentation. This behaviour is explained in terms of the mobile proton model for peptide fragmentation that can be used as an indication for the presence of arginine when unknown microcystins are analyzed. In‐source CID was applied to the characterization of microcystins released into water from a Microcystis aeruginosa culture (UTCC299) (UTCC: University of Toronto Culture Collection of Algae and Cyanobacteria). Six microcystins were detected in extracts from UTCC299: I, [D‐Asp3]MCYST‐LR; II, MCYST‐LR; III, isomer of MCYST‐LR; IV, isomer of methyl MCYST‐LR; V, [D‐Asp3, Glu(OCH3)6]MCYST‐LR; and VI, [D‐Glu(OCH3)6]MCYST‐LR. In‐source CID provided mass spectral patterns similar to those obtained by CID in the collision cell of the mass spectrometer but was more sensitive for the analysis of microcystins. Copyright © 2005 John Wiley & Sons, Ltd.
Gold coating of non‐conductive membranes before matrix‐assisted laser desorption/ionization tandem mass spectrometric analysis prevents charging effect
Authors: Scherl Alexander , Zimmermann‐Ivol Catherine G. , Dio Joel Di , Vaezzadeh Ali R. , Binz Pierre‐Alain , Amez‐Droz Michel , Cochard Roland , Sanchez Jean‐Charles , Glückmann Matthias , Hochstrasser Denis F.
Published: January 2005

Acquisition of tandem mass spectra from peptides or other analytes deposited on non‐conductive membranes is inhibited on instruments combining matrix‐assisted laser desorption/ionization with tandem time‐of‐flight analyzers (MALDI‐TOF/TOF™) due to a charging effect. A thin layer of gold renders the membrane conductive. This allows adequate data acquisition on MALDI‐TOF/TOF™ systems. Therefore, this methodology extends the capacity of the molecular scanner concept to tandem mass spectrometry. Copyright © 2005 John Wiley & Sons, Ltd.
Segmented post‐column analyte addition; a concept for continuous response control of liquid chromatography/mass spectrometry peaks affected by signal suppression/enhancement
Authors: Kaufmann Anton , Butcher Patrick
Published: January 2005

A novel technique, “segmented post‐column analyte addition”, is proposed to visualize and compensate signal suppression/enhancement effects in electrospray ionization tandem mass spectrometry (ESI‐MS/MS). Instead of delivering a constant flow of analyte solution between the liquid chromatography (LC) column exit and the ESI interface into the eluent resulting from LC separation of analyte‐free matrix in order to determine retention time widows in which suppression/enhancement is unimportant (King et al., J. Am. Soc. Mass Spectrom. 2000; 11: 942), segmented packets of analyte‐containing solvent and analyte‐free solvent were infused into an LC eluent resulting from separation of an analyte‐containing sample. The obtained, superimposed, periodic spikes are much narrower than the analyte peak eluting from the column. The height of the spikes is affected by signal suppression phenomena to the same extent as the analyte signal, and hence variations of the spike height can be used to correct the peak area of analyte peaks affected by signal suppression/enhancement. Copyright © 2005 John Wiley & Sons, Ltd.
Limit distribution of the number of consecutive records
Authors: Chern Hua‐Huai , Hwang Hsien‐Kuei
Published: January 2005

A succinct series expression is derived for describing the limit distribution of the number of timesrconsecutive elements are all records (in a sequence of independent and identically distributed random variables with a common continuous distribution) for allr≥ 2. Previously, only the limit distributions forr= 1, 2, and 3 were known. © 2005 Wiley Periodicals, Inc. Random Struct. Alg., 2005
Evolution of the local structure in GaN:O thin films grown by ion‐assisted deposition with film thickness
Authors: Ariza M. J. , Koo A. , Trodahl H. J. , Ruck B. J. , Bittar A. , Jones D. J. , Bonnet B. , Rozière J. , Moscovici J.
Published: January 2005

Optical and optoelectronic properties of gallium nitride strongly depend on the synthesis procedure, which may be related to specific structural characteristics of GaN inherent to each preparation condition. Amorphous and nanocrystalline GaN films have been prepared by ion‐assisted deposition (IAD). The films prepared at 10−5 Torr for <50 min have shown exploitable optoelectronic properties, in spite of the high concentration of oxygen of these films (up to 25 at.%). We study here the evolution of the local structure around Ga atoms as the deposition time increases. Five IAD GaN films of thickness ranging between 140 and 450 nm on silicon substrates were analysed by x‐ray absorption fine structure (XAFS) at the Ga K‐edge. The first and second shells of neighbouring atoms are clearly identified in the radial distribution functions at approximately 1.9 and 3.2 Å, respectively. In all of the films, Ga seems to be tetrahedrally coordinated to four nitrogen atoms, some of which may be substituted by oxygen. For deposition times <50 min, analysis of both x‐ray adsorption near‐edge structure (XANES) and extended x‐ray adsorption fine structure (EXAFS) regions indicates that the material is highly amorphous. Above this threshold, a peak corresponding to the first coordination sphere of Ga atoms becomes discernible and increases in intensity for longer deposition times, indicating that the second shell of atoms is now more ordered. The pseudo Debye–Waller factor of the Ga shell is used for monitoring the average degree of amorphization in an ∼100 nm thick top layer, which seems to be related to the film oxygen content. The XAFS results are compatible with a layered distribution of crystallinity, as has been suggested previously for these films. Copyright © 2005 John Wiley & Sons, Ltd.
Growth and SIMS study of d.c.‐sputtered indium oxide films on silicon
Authors: Malar P. , Mohanty Bhaskar Chandra , Balamurugan A.K. , Rajagopalan S. , Tyagi A.K. , Kasiviswanathan S.
Published: January 2005

Indium oxide thin films were grown onto Si and quartz substrates by d.c. reactive sputtering of elemental indium. X‐ray diffraction and transmission electron microscopy studies confirmed the single‐phase and polycrystalline nature of the films. Secondary ion mass spectrometry investigations of In2O3/Si structures showed the formation of an inhomogeneous interface region ∼20 nm thick between In2O3 and Si. The overall feature of the interface remained the same under annealing in an oxygen atmosphere, but annealing in an argon atmosphere drastically altered the nature of the interface. The observations indicate that interface formation and stability depend critically on the availability of oxygen. Copyright © 2005 John Wiley & Sons, Ltd.
Binding property and structure of aromatic isocyanide self‐assembly monolayers on Ag and Au surfaces
Authors: Kim Sungil , Ihm Kyuwook , Kang Tai‐Hee , Hwang Sungu , Joo Sang‐Woo
Published: January 2005

The binding property of p‐biphenyl isocyanide self‐assembled monolayers (SAMs) on Au and Ag was investigated by temperature‐dependent surface‐enhanced Raman spectroscopy (SERS). p‐Biphenyl isocyanide was found to desorb on Ag at a low temperature of ∼393 K whereas it appeared to remain enduring at a high temperature of ∼453 K for Au. Structures of p‐biphenyl isocyanide SAMs on Au and Ag flat films were checked by means of near‐edge x‐ray absorption fine structure spectroscopy (NEXAFS) at the two different normal (90° ) and grazing (20° ) angles of the incident x‐ray beam. Our results suggested that the SAMs prepared by p‐biphenyl isocyanide should have a relatively disordered structure even at room temperature on both Au and Ag, as indicated from an insubstantial change in NEXAFS spectra at the two different angles from those of p‐biphenyl thiolate and p‐biphenyl methanethiolate. The weakness of the isocyanide–metal bond in comparison with the sulphur–metal bond may result in both low surface coverage and orientational disorder. A density functional theory calculation method was employed to attempt to explain the difference in stability for phenyl isocyanide on Ag and Au surfaces. Our calculation result yielded a lower binding energy of phenyl isocyanide on Ag than that on Au, consistent with the temperature‐dependent Raman results. Copyright © 2005 John Wiley & Sons, Ltd.
Ultrathin SiO2 on Si. VI. Evaluation of uncertainties in thickness measurement using XPS
Authors: Seah M. P.
Published: January 2005

Measurements of the thicknesses of SiO2 on Si in the range 1.5–8 nm can be made by XPS with precisions as high as 0.025 nm at one standard deviation, but in the past this has been overshadowed by systematic uncertainties of the order of 20% of the thickness arising from the uncertainty in the relevant electron attenuation length. This is shown no longer to be the case. An analysis is presented, of the contributions to the measurement precision arising from the counting statistics, peak fitting and setting of the emission angle for the detected electrons. With traditional commercial equipment, the angle‐setting accuracy of 0.5° can be the limiting factor. For comparison between laboratories, further terms degrade the comparability: a typical 1% from the consistency of any samples used for the comparison; a more significant term from the angular acceptance of those spectrometers that accept more than ±10° of the emission angles; contributions from the variability of the procedures for analysing the peak intensities for the quantification; and variations in the algorithms used. For absolute quantification in the above thickness range, a recent calibration of the attenuation length enables the uncertainty to be kept to ∼2% at 95% confidence but the above variability in procedures in general analytical laboratories leads to this value degrading often to as poor as 0.4 nm, again at 95% confidence. Copyright © 2005 John Wiley & Sons, Ltd.
Effects of annealing on the surface structure of Ga‐isotope‐implanted single‐crystal ZnO
Authors: Sakaguchi Isao , Hishita Syunichi , Ryoken Haruki , Sato Yoshiyuki , Haneda Hajime
Published: January 2005

We studied the effects of Ga isotope implantation on surface structure using single‐crystal (0001) ZnO with an atomically flat surface. The surface morphology with steps and terraces was greatly changed by Ga implantation and post‐annealing: the step‐and‐terrace structure was suppressed by Ga implantation but a step‐and‐terrace structure appeared on the surface after post‐annealing at 900 °C for 4 min. The diffusion of Ga towards the surface through dislocation pipes at a density of up to 5 × 108 cm−2 was the dominant mechanism, and a significant amount of Ga moved from the implanted layer to the surface. The reaction between Ga and ZnO during post‐annealing appeared to improve sheet resistance and surface morphology. Copyright © 2005 John Wiley & Sons, Ltd.
Preferential sputtering observed in Auger electron spectroscopy sputter depth profiling of AlAs/GaAs superlattice using low‐energy ions
Authors: Mizuhara Y. , Bungo T. , Nagatomi T. , Takai Y.
Published: January 2005

Auger electron spectroscopy (AES) sputter depth profiling of an ISO reference material of the GaAs/AlAs superlattice was investigated using low‐energy Ar+ ions. Although a high depth resolution of ∼1.0 nm was obtained at the GaAs/AlAs interface under 100 eV Ar+ ion irradiation, deterioration of the depth resolution was observed at the AlAs/GaAs interface. The Auger peak profile revealed that the enrichment of Al due to preferential sputtering occurred during sputter etching of the AlAs layer only under 100 eV Ar+ ion irradiation. In addition, a significant difference in the etching rates between the AlAs and GaAs layers was observed for low‐energy ion irradiation. Deterioration of the depth resolution under 100 eV Ar+ ion irradiation is attributed to the preferential sputtering and the difference in the etching rate. The present results suggest that the effects induced by the preferential sputtering and the significant difference in the etching rate should be taken into account to optimize ion etching conditions using the GaAs/AlAs reference material under low‐energy ion irradiation. Copyright © 2005 John Wiley & Sons, Ltd.
Acid and basic functionalities of nitrogen and carbon dioxide plasma‐treated polystyrene
Authors: Wang Meng‐Jiy , Chang You‐Im , Poncin‐Epaillard F.
Published: January 2005

The choice of plasma gas can determine the interaction between material and plasma and therefore the applications of the treated materials. Nitrogen plasma can integrate functional groups such as primary amines and carbon dioxide plasma can incorporate carboxylic groups on the surface of polymers. For specific adhesion such as bio‐adhesion, polar groups must be attached to the surface to enhance bio‐film formation but the acidic or basic character also controls the adhesion mechanism.

Nitrogen and carbon dioxide plasmas are chosen to treat the surface of polystyrene and to show the effects of different functionalizations, i.e. attachment of acid or basic groups and degradation are compared in the present work.

Nitrogen‐containing plasma induces mainly weak degradation at a rate of ∼0.13 µg cm−2s−1. The roughness of the treated surface remains mostly unchanged. Functionalization leads to amino group attachment at a concentration of 1.2 sites nm−2. We found that carbon dioxide plasma treatment shows more drastic degradation with a rate three times higher than that of nitrogen plasma and can create more functional groups (4.5 sites nm−2) at mild plasma treatment. However, the roughness of the surface is altered. In both cases the aromatic groups are degraded through the plasma treatment (again this is more evident with the CO2 plasma) and the induced functionalization was shown to be quick (the upper monolayer of polystyrene film can be functionalized rapidly). Copyright © 2005 John Wiley & Sons, Ltd.
Monte‐Carlo simulation of spatial distribution of x‐rays in multi‐film targets. II: Spatial distribution of continuous x‐rays and temperature elevation in W/Al film targets
Authors: Yoshioka Akihiro , Yamaguchi Yoshikazu , Tamura Keiji , Shimizu Ryuichi
Published: January 2005

A Monte‐Carlo simulation written in C++ has been developed to describe spatial distributions of energy dissipation and x‐rays generated by penetrating kilovolt electrons in a multi‐film target. To evaluate the x‐ray source, especially its size and intensity, the use of brightness is proposed as a figure of merit.

The Monte‐Carlo simulation approach was applied to a W (5 µm)/Al (200 µm) film target, which has been in practical use as an x‐ray source of small size with high emissivity. The result demonstrates that the experiment had considerable success. The optimum operating condition for the W (5 µm)/Al (200 µm) target in practical use has also been proposed by considering temperature elevation, spot size of electron beam, x‐ray source size and x‐ray intensity. Copyright © 2005 John Wiley & Sons, Ltd.
Relationships between the constructs of a theory of curriculum implementation
Authors: Rogan John , Aldous Colleen
Published: January 2005

Planned educational change occurs regularly throughout the world. With the enormous political change the 1994 elections brought to South Africa, a complete change in education policies was called for. The new Curriculum 2005 (C2005; Department of Education, RSA, 1997) embraced new teaching and learning approaches such as outcomes‐based education and learner‐centered teaching practices. To explore the progress of the implementation of C2005, a theoretical framework specifically designed to elucidate curriculum implementation in developing countries was applied to 10 case studies. The framework consists of interrelating constructs with subconstructs which impact on curriculum implementation. It enables one to look at the levels of implementation achieved both in terms of the capacity of the school and the extent to which outside support and pressure is provided. The case studies were carried out in a representative sample of schools in Mpumalanga, one of the nine South African provinces. The aim of this article is to investigate the possible interrelationships of the constructs and the subconstructs. Some predictable relationships emerged from the data while other expected relationships failed to materialize. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 313–336, 2005
Prenatal diagnosis of pulmonary sequestration using three‐dimensional power Doppler ultrasound
Authors: Ruano R. , Benachi A. , Aubry M.‐C. , Revillon Y. , Emond S. , Dumez Y. , Dommergues M.
Published: January 2005

Objective

To investigate the contribution of three‐dimensional power Doppler ultrasound to the prenatal diagnosis of pulmonary sequestration.

Methods

Prenatal three‐dimensional power Doppler ultrasound was used to screen for an abnormal pulmonary blood supply in eight fetuses with hyperechogenic lung lesions and to image the pulmonary blood supply in 50 normal controls. A comparison was made with postnatal findings.

Results

Postnatally the eight pulmonary lesions were found to be an isolated pulmonary sequestration (n = 3), a microcystic congenital adenomatoid malformation (n = 4), and a mixed (macrocystic and microcystic) congenital adenomatoid malformation (n = 1). Prenatal three‐dimensional power Doppler ultrasound demonstrated an abnormal blood supply in all cases of pulmonary sequestration and in none of the other cases. Among the three cases that turned out to be pulmonary sequestrations, conventional two‐dimensional ultrasound failed to identify the feeding vessel in one case and identified it at a later stage of gestation than did three‐dimensional power Doppler in the other two.

Conclusion

Prenatal three‐dimensional power Doppler ultrasound may be useful in identifying the feeding vessel and thus establishing the diagnosis of pulmonary sequestration in the presence of a hyperechogenic pulmonary lesion, allowing its differentiation from congenital cystic adenomatoid malformation. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Massive myocardial calcification in second‐trimester fetuses: antenatal detection and causes
Authors: Chan Y. F. , Sampson A.
Published: January 2005

Massive myocardial calcifications were detected by antenatal ultrasound examination in four second‐trimester fetuses. In one fetus, multiple cardiac rhabdomyomas were the initial diagnosis. One fetus presented with arthrogryposis and the brain and spinal cord showed severe hypoxic‐ischemic damage. One fetus was hydropic and had severe cardiac malformations. The fourth fetus had congenital heart block and maternal serum was positive for anti‐Ro and anti‐La antibodies. Myocardial calcifications in the first three fetuses were most likely to be caused by hypoxic‐ischemic damage to the heart, and immunological mechanisms were responsible in the other fetus. Antenatally detected myocardial echogenic foci in a fetus leading to a termination of pregnancy or associated with fetal death should be investigated with a full postmortem examination. It is important to confirm the presence of calcifications as distinct from a rhabdomyoma as genetic counseling is completely different. The demonstration of associated lesions in other organs also helps to explain the pathogenesis underlying this condition. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal intra‐abdominal umbilical vein varix: what is the clinical significance?
Authors: Fung T. Y. , Leung T. N. , Leung T. Y. , Lau T. K.
Published: January 2005

Objective

To assess the clinical significance of fetal intra‐abdominal umbilical vein (FIUV) varix.

Methods

We reviewed all cases of FIUV varix diagnosed in a university hospital from 1994 to 2003 and searched the English literature for cases of prenatal diagnosis of FIUV varix. The FIUV was considered dilated when the measurements were above 2 SD of the mean for gestational age. Cases reported in the literature were included if they met the diagnostic criteria for FIUV varix.

Results

Between 1994 and 2003, 13 fetuses were diagnosed in our hospital as having FIUV varix. Review of the literature revealed an additional 80 cases. Fetal outcome was available for analysis in 91 cases. Additional sonographic abnormalities were detected prenatally in 29 cases (31.9%), most commonly anomalies of the cardiovascular system (including structural and functional abnormalities), hydropic features and anemia. There were nine (9.9%) cases of chromosomal abnormalities. All except one had associated sonographic abnormalities. There were 12 (13%) perinatal losses. Only 54 cases (59.3%) of fetuses with FIUV varix had a normal obstetric outcome. In the 62 cases with isolated FIUV varix, there were five unexplained intrauterine deaths (8.1%) occurring between 29 and 38 weeks of gestation. The incidence of complications, which included intrauterine death, thrombosis of the umbilical vein and abnormal antenatal cardiotocogram, were significantly higher (P = 0.01, Fisher's exact test) if the diagnosis of FIUV varix was made before 26 weeks.

Conclusions

FIUV varix is associated with a high incidence of fetal anomalies and obstetric complications. Detailed sonography is necessary to exclude fetal anomalies. Karyotyping should be offered when additional fetal abnormalities are detected. Intensive surveillance including color Doppler ultrasound should be started from the moment of diagnosis until delivery, especially in those cases presenting early in pregnancy. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Determination ofE2for Nitride Ceramics Using FE-SEM and the Duane–Hunt Limit Procedure
Authors: Brochu M. , Demers H. , Gauvin R. , Pugh M.D. , Drew R.A.L.
Published: January 2005

This work demonstrates the possibility of using the Duane–Hunt limit of the bremsstrahlung to determineE2values of Si3N4and AlN ceramics. TheEDHLversusE0graph demonstrates that for conductive materials, the experimental curve is parallel to the theoretical (EDHL=E0), but both curves cross in the case of insulators. The intersection points (E2value), are 3.01 keV for Si3N4and 2.67 keV for AlN. Imaging of ceramic grain structure at high magnification was performed to demonstrate the validity of the calculatedE2values.
Off-Axis Electron Holography of Unbiased and Reverse-Biased Focused Ion Beam Milled Sip-nJunctions
Authors: Twitchett Alison C. , Dunin-Borkowski Rafal E. , Hallifax Robert J. , Broom Ronald F. , Midgley Paul A.
Published: January 2005

Off-axis electron holography is used to measure electrostatic potential profiles across a siliconp-njunction, which has been prepared for examination in the transmission electron microscope (TEM) in two different specimen geometries using focused ion beam (FIB) milling. Results are obtained both from a conventional unbiased FIB-milled sample and using a novel sample geometry that allows a reverse bias to be applied to an FIB-milled samplein situin the TEM. Computer simulations are fitted to the results to assess the effect of TEM specimen preparation on the charge density and the electrostatic potential in the thin sample.
Provision of IMRT in the UK. Part 1: A review of planning, delivery and related technologies
Authors: Baker C.R. , Hardy V.
Published: January 2005

The concept of intensity-modulated radiotherapy is now familiar to everyone working in radiotherapy in the UK. To date however, the majority of UK radiotherapy departments have yet to offer this technique clinically. Implementation of IMRT represents a significant change in practice from the delivery of conventional or conformal treatment, requiring careful planning and a full understanding of the issues and new technology involved.

This paper provides a review of the stages involved in the IMRT process; from localisation and immobilisation through inverse treatment planning and quality control to delivery and verification, highlighting those aspects that represent a significant change in practice or approach.

Current and future developments that are expected to enhance or provide alternatives to IMRT, such as developments in radiobiological modelling, functional imaging, tomotherapy and proton therapy are discussed.
Occupational stresses and coping mechanisms of therapy radiographers – a qualitative approach
Authors: French H. C.
Published: January 2005

It is believed that health care workers are particularly susceptible to developing stress-related illness because of the nature of their work. The purpose of this research was to identify occupational stresses that may or may not be unique to therapy radiographers, identify the coping mechanisms that are used to combat work-related stress and gain insight into the lived experiences of this group of therapy radiographers. A phenomenological (qualitative) approach was used to identify the radiographers' perception of occupational stresses and coping mechanisms. Data collection was through in-depth interviews that were transcribed and analysed using Colaizzi methodology. The results identified stresses within the following categories: personal performance, patient contact, working environment, communication, management, professional behaviour and departmental working. These results support the stresses identified through other research studies on health care workers. Coping mechanisms identified include Social Support, Confrontive Coping, Escape-Avoidance, Self-Controlling, Distancing and Positive Reappraisal. The most frequently used coping mechanisms were social support, confrontive coping and escape-avoidance. This research has also identified a new stress; the stress associated with the ‘potential to make errors’ i.e. the acute awareness of the damaging effects of high energy X-rays if a mistake is made.

This research has attempted to provide insight into the working world of the therapy radiographer and to discover the meaning and information specific to their ‘lived experience’. It is hoped that this research provides the reader with a deeper understanding of the nature and meaning of the experience.
Does the photon have a future? An overview of potential benefits associated with hadron therapy
Authors: Bridge P.
Published: January 2005

Hadron therapy uses sub-atomic particles to deliver radiotherapy and has the capability of delivering to an increased depth compared to photons. This offers the potential of conformal therapy without the increased integral dose associated with intensity-modulated radiotherapy (IMRT). In addition, there is the possibility of hadron therapy having increased relative biological effectiveness (RBE) when compared to photons. There is increasing interest in this topic currently with the possibility of a second UK hadron therapy facility being under discussion.

This paper introduces the concept of hadron therapy and presents an evaluation of the potential benefits associated with it. Planning studies and clinical trials are reviewed in order to assess the impact that hadron therapy would have on patient management. Costs and other factors affecting the implementation of a hadron therapy facility are presented.

The proven benefits of hadron therapy are easily demonstrated by the planning studies with increased conformity and reduced integral dose over a range of tumour sites. Simple hadron plans consistently out-perform complicated IMRT plans. The costs associated with hadron facilities are higher than for photons, but they offer simplified planning due to the inherent conformality achievable with simple hadron beams. As costs decrease and technology improves, the benefits of hadron therapy may result in the replacement of the photon for radiotherapy.
Radiographer review clinics: breast cancer
Authors: Cameron J.
Published: January 2005

Acute skin reactions are expected in patients receiving radical radiotherapy to the breast. Side effects of other adjuvant treatments such as chemotherapy and hormonal therapy can further impact upon patients' well being. As a result these patients are routinely monitored throughout their radiotherapy treatment at a review clinic. Previously the domain of doctors, radiographers are expanding their existing role and becoming more involved in review clinics.

This paper highlights the key side effects reported by actual patients from their adjuvant treatment and strategies to alleviate these side effects. It also reflects upon the experience, both positive and negative, of undertaking clinical review and role expansion in general.
Conventional and contemporary management approaches for the treatment of vestibular schwannomas: Microsurgery versus radiosurgery, a literature review
Authors: Hickey K.
Published: January 2005

The management of intracerebral tumours has always provided us with a challenge when deciding upon the best treatment approach. However, when such tumours are benign and located in close proximity to critical structures, tumour management becomes all the more challenging.

The treatment of vestibular schwannomas has always posed such problems because of their anatomical proximity to critical structures such as the brainstem and several cranial nerves. Through a comprehensive literature appraisal, this article evaluates the problems associated with conventional treatment options and discusses how technical advances over the past decades have affected disease management and therefore impacted on the range and type of treatment modalities employed. In addition, it highlights the role of alternative contemporary approaches in the management of vestibular schwannomas.
Symptomatic treatment of radiation-induced mucositis in head and neck cancer: current practice, literature review and evidence-based recommendations
Authors: Pacitti C. A.
Published: January 2005

Background: Oro-pharyngeal mucositis is a common complication of radical radiotherapy for head and neck cancer and may be the major treatment dose-limiting factor. Symptomatic treatment, however, appears variable and often ineffective.

Aim: To assess current UK practice, review published literature to assess the evidence base for current mucositis interventions and develop an evidence-based protocol for local use based on this knowledge.

Methods: An open-ended, qualitative questionnaire was sent to twenty UK Radiotherapy Departments to provide a sample of the current use of symptomatic treatments, including analgesia. A literature search was conducted using Medline and Cochrane databases to provide an evidence-based recommendation for the development of an effective local management protocol.

Results: Sixteen departments returned completed questionnaires (80% response rate). Eleven different pharmaceutical preparations were being used for symptomatic relief, with benzydamine (Difflam Oral Rinse) and Mucaine being the most commonly prescribed (in five departments each). Eleven different analgesics were being prescribed ranging from soluble aspirin to continuous infusion of diamorphine. The conclusion of a Cochrane Collaboration systematic review of the literature found weak or no evidence for the use of current interventions as effective agents for the relief or eradication of treatment-related mucositis.

Conclusions: For such a common and important treatment toxicity, there is no consistent symptomatic management and there is no good evidence-base for the use of any of the presently prescribed medications. Clinical trials have involved small samples and little replication of studies. Evidence does exist for the importance of good oral hygiene before, during and after treatment, and this has formed the basis of our new departmental protocol with discontinuation of the use of commercial mouthwashes.
Tropical Pacific link to the two dominant patterns of atmospheric variability
Authors: Lin Hai , Derome Jacques , Brunet Gilbert
Published: January 2005

Using the NCEP/NCAR global reanalysis data for 51 boreal winters, a convective index (CI) for the tropical Pacific is constructed. It is found that the extreme positive and negative events of the CI are connected to the positive phases of the two dominant modes of the extratropical atmospheric variability, i.e., the PNA and the NAO, respectively. The same analysis is applied to the output of a 201‐year integration of a global air‐sea coupled general circulation model. Results consistent with the observations are obtained.
Testing the influence of the Central American Seaway on orbitally forced Northern Hemisphere glaciation
Authors: Klocker A. , Prange M. , Schulz M.
Published: January 2005

Utilizing a climate model of intermediate complexity, we test the hypothesis that the Pliocene closure of the Central American Seaway was a necessary precondition for orbitally triggered Northern Hemisphere glaciation. We conduct a series of sensitivity experiments in order to analyze the isolated and combined effects of Panama closure and orbital forcing on Northern Hemisphere perennial snow cover. While orbital forcing efficiently controls the extension of perennial snow cover, the model results suggest that the closure of the Central American Seaway did not intensify orbitally forced glaciation in high northern latitudes.
Short‐term climate response to a freshwater pulse in the Southern Ocean
Authors: Richardson Glen , Wadley Martin R. , Heywood Karen J. , Stevens David P. , Banks Helene T.
Published: January 2005

The short‐term response of the climate system to a freshwater anomaly in the Southern Ocean is investigated using a coupled global climate model. As a result of the anomaly, ventilation of deep waters around Antarctica is inhibited, causing a warming of the deep ocean, and a cooling of the surface. The surface cooling causes Antarctic sea‐ice to thicken and increase in extent, and this leads to a cooling of Southern Hemisphere surface air temperature. The surface cooling increases over the first 5 years, then remains constant over the next 5 years. There is a more rapid response in the Pacific Ocean, which transmits a signal to the Northern Hemisphere, ultimately causing a shift to the negative phase of the North Atlantic Oscillation in years 5–10.
Chemical interactions between mineral dust particles and acid gases during Asian dust events
Authors: Ooki Atsushi , Uematsu Mitsuo
Published: January 2005

Acid gas reactions during the passage from the source regions to the western North Pacific modify the chemical characteristics of Asian mineral dust particles as they pass through heavily industrial regions. We conducted aerosol samplings to investigate the interaction of mineral dust particles with acid gases in the western North Pacific region during the high‐dust season. The concentration peaks of NO3− and mineral dust particles were in the coarse mode range (D > 1.25 μm) in all aerosol samples, while non‐sea‐salt‐(nss)‐SO42− had an apparent peak in the coarse mode range only in an Asian dust event that experienced rain. Nitrate was the dominant acid substance associated with the mineral dust particles rather than nss‐SO42−. In the urban air of Tokyo we also conducted an in situ experiment to react ambient acid gases with mineral dust particle loaded on a filter. The in situ experiment indicated that HNO3 had reacted with mineral dust particles much more efficiently than SO2 had. HNO3 (+NO2) and HCl accounted for large fractions (48% and 40%) of acid gases that reacted with mineral dust particles, while SO2 accounted for a small fraction (12%). The high adsorption of HNO3 on mineral dust particles would change their surface properties from hydrophobic to hygroscopic and form an efficient mechanism to remove nitrogen compounds to the ocean surface layer.
Characteristics of instabilities in the mesopause region over Maui, Hawaii
Authors: Li Feng , Liu Alan Z. , Swenson Gary R.
Published: January 2005

Characteristics of convective and dynamical instabilities in the mesopause region (between 85 and 100 km) over Maui, Hawaii (20.7°N, 156.3°W) are investigated using 19 nights, ∼133 hours of high‐resolution wind and temperature data obtained by the University of Illinois Na wind/temperature lidar during the Maui Mesosphere and Lower Thermosphere (Maui MALT) campaigns. The mean probabilities of convective and dynamical instabilities are observed to be ∼3 and 10%, respectively, but there is considerable night‐to‐night variation. At any given time the probability that an unstable condition is found at some altitudes in the 85–100 km range is ∼90%. The Maui MALT data exhibit a distinct trend for N2 to increase with wind shear and vice versa. This correlation has important implications in the understanding of the development of instabilities. The night of 11 April 2002 is studied in detail in order to investigate the spatial and temporal structures of N2, wind shear, and convective and dynamical instabilities. A close linkage between instability and the mesosphere inversion layers (MILs) is identified. Most of the convectively and dynamically unstable regions are located above the MILs, with a tendency for dynamical instability to develop below convective instability. It is found that the vertical variations of N2 are often correlated with those of wind shear, but with a phase shift such that the maxima and minima of N2 are located ∼0.5–1 km below those of wind shear. Because of this shift, dynamical instability tends to develop in the region above the maximum wind shear, where relatively small N2 is observed to be associated with large wind shear. We also found that the wind shear is dominated by the contribution of the meridional wind, especially when the wind shear is strong. Possible mechanisms for the observed features are discussed.
Impact of Antarctic polar vortex occurrences on total ozone and UVB radiation at southern Argentinean and Antarctic stations during 1997–2003 period
Authors: Pazmiño Andrea F. , Godin‐Beekmann Sophie , Ginzburg Máximo , Bekki Slimane , Hauchecorne Alain , Piacentini Rubén D. , Quel Eduardo J.
Published: January 2005

The evolution of total ozone and surface UV radiation over some stations in the southern region of South America and in Antarctica in relationship with polar vortex occurrences is analyzed using Total Ozone Mapping Spectrometer total ozone measurements and local surface UV data for the 1997–2003 period. The data are classified as a function of the position of the stations with respect to the polar vortex using equivalent latitude at 550 K isentropic level. The study of vortex occurrences showed that Ushuaia station (54.9°S) was located ∼40% of the cases in the edge of the vortex and 5% inside the vortex core during the winter‐spring period. Concerning the Marambio (62.2°S) and Dumont d'Urville (66.4°S) stations, located on the shore of the Antarctic continent, the analysis shows a zonal asymmetry with respect to the center of the vortex. Marambio is located around 60% of the time inside the vortex, while Dumont d'Urville is predominantly at the edge of or outside the vortex. The evolution of the equivalent latitude of the stations in the anomalous 2002 winter presents a different behavior with respect to other years in the 1997–2003 period. The persistence of the vortex core above the stations is in average 1.8 days over Ushuaia and 7.1 days over Marambio in October during the 1997–2003 period with corresponding mean total ozone columns of 208.2 and 181.4 Dobson units, respectively. When the stations are inside the vortex, the total ozone columns are generally larger at Ushuaia than at Marambio in October during the 1997–2003 period. Finally, the impact of ozone‐depleted air mass occurrences on ultraviolet radiation is evaluated by relating total ozone and UV erythemal dose measured at the stations. Twofold or threefold UV dose increases were reached in the 55°–65° southern latitude region during vortex overpasses, reaching maximum UV dose around 5 kJ/m2. The average increase of UV dose could be computed at the stations considered in the study when the measurement sampling and the number of vortex occurrences was sufficient. An average increase of 67.6% of the erythemal UV dose was found in October at Ushuaia over the years 1997, 1998, and 2000. This value is strongly weighted by vortex occurrences over the station in 2000. At Marambio an average UV increase of 47.4% was found over the years 1999 and 2000. Midlatitude stations like Comodoro Rivadavia (45.8°S) are generally little affected by vortex intrusions. Nevertheless, the maximum UV dose can increase by more than 50% when the vortex passes over the station.