bluuebunny/crossref_metadata_2025 huggingface dataset:
Bone response to endosseous titanium implants surface‐modified by blasting and chemical treatment: A histomorphometric study in the rabbit femur
Authors: Park Jin‐Woo , Jang Il‐Sung , Suh Jo‐Young
Published: June 2007

This study evaluated the effects of the addition of oxide structure with submicron‐scale porous morphology on the periimplant bone response around titanium (Ti) implants with microroughened surfaces. Hydroxyapatite‐blasted Ti implants with (experimental) and without (control) a porous oxide structure produced by chemical treatment were investigated in a rabbit femur model. Surface characterizations and in vivo bone response at 4 and 8 weeks after implantation were compared. The experimental implants had submicron‐scale porous surface structure consisted of anatase and rutile phase, and the original Ra values produced by blasting were preserved. The histomorphometric evaluation demonstrated statistically significantly increased bone‐to‐implant contact (BIC) for experimental implants, both in the three best consecutive threads (p < 0.01) and all threads (p < 0.05) at 4 weeks. There was no remarkable difference in the BIC% or bone area percentage between the two groups at 8 weeks. The porous Ti oxide surface enhanced periimplant bone formation around the Ti implants with microroughened surfaces at the early healing stage. Based on the results of this study, the addition of crystalline Ti oxide surface with submicron‐sized porous morphology produced by chemical treatment may be an effective approach for enhancing the osseointegration of Ti implants with microroughened surfaces by increasing early bone‐implant contact. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Mesoporous silica from rice hull ash
Authors: Sánchez‐Flores Norma A , Pacheco‐Malagón Graciela , Pérez‐Romo Patricia , Armendariz Héctor , de L Guzmán‐Castillo María , Saniger José M , Fripiat Jose J
Published: June 2007

In the synthesis of mesoporous materials, the use of a template with an adequate porosity is normally favoured. As far as silica is concerned, many sophisticated procedures directed towards this goal have been published. It is already well documented that rice hull contains relatively pure silica after combustion of the residual organic matter. The authors of this contribution have recently demonstrated that large surface area silicates react with glycerol around 200 °C to give depolymerized silica with a chemical composition similar to that of poly‐alkoxides. The interest in this so‐called depolymerization is to allow easy formation of reactive gels which retain the memory of the porous structure of the original starting material. Rice hull ash (RHA), obtained after combustion of the organic residues at 500 °C, gives a silica characterized by mesopores with an average diameter about 3.5 nm. It is shown that RHA reacts with glycerol at 200 °C to form gels which, after hydrolysis and calcination, retain the mesoporous character. The hydrolysis procedure and especially, the pH is important for the distribution of the mesoporosity. The very simple reaction of a by‐product of the food industry with glycerol, a “green reagent”, gives a mesoporous solid silica in the form of a reactive gel, with many potential uses. Its use in a new procedure for the synthesis of a supported ZSM‐5 zeolite has been demonstrated. Copyright © 2007 Society of Chemical Industry
Optimization of nitrilase production from a new thermophilic isolate
Authors: Khandelwal Amit Kumar , Nigam Vinod Kumar , Choudhury Bijan , Mohan Medicherla Krishna , Ghosh Purnendu
Published: June 2007

A new thermostable nitrilase‐producing isolate identified as Streptomyces sp. MTCC 7546 has been studied extensively for the optimization of enzyme production operating in batch mode. The benzonitrile was observed as inducer of nitrilase production. The isolate showed maximum nitrilase production after 24 h of incubation at optimal conditions. The strain grows well on a variety of carbon sources and produces the nitrilase that catalyses the hydrolysis of nitriles to acids without formation of amides. The enzyme is mostly active against mono‐ and di‐aliphatic nitriles (10 mmol L−1) at pH of 7.4 and at a temperature of 50 °C. Copyright © 2007 Society of Chemical Industry
The synthesis of three isotopomers of 2‐methyl‐2‐(4‐[3‐[1‐(4‐methylbenzyl)‐5‐oxo‐4,5‐dihydro‐1H‐[1,2,4]triazol‐3‐yl]propyl]phenoxy)propionic acid, a potent and selective peroxisome proliferator‐activated receptor alpha agonist
Authors: Kuo Fengjiun , Clodfelter Dean K. , Farid Nagy A. , Wheeler William J. , McKendry Lennon H.
Published: June 2007

Although fenofibrate (1a) is commercially available and clinically effective in lowering serum triglycerides, its activity and sub‐type selectivity at the PPARα receptors are only moderate; therefore, there exists a need for more potent and sub‐type selective PPARα agonists. To that end, discovery efforts have identified 2‐methyl‐2‐(4‐[3‐[1‐(4‐methylbenzyl)‐5‐oxo‐4,5‐dihydro‐1H‐[1,2,4]triazol‐3‐yl]propyl]phenoxy)propionic acid (2), a potent and selective human PPARα receptor agonist. In support of pre‐clinical ADME studies and bioanalysis, three isotopomers of 2 have been synthesized. The results of these efforts are described below. Copyright © 2007 John Wiley & Sons, Ltd.
Raman scattering studies on nanocrystalline BaTiO3 Part II—consolidated polycrystalline ceramics
Authors: Shiratori Y. , Pithan C. , Dornseiffer J. , Waser R.
Published: June 2007

BaTiO3 dense ceramics with different grain sizes from 5.6 µm down to 35 nm were thoroughly studied by Raman spectroscopy. The temperature characteristics of optical phonons were compared with those obtained for powders. The micrograined ceramic revealed the well‐known spectrum profiles and transitions, typical for bulk BaTiO3. On the other hand, the Raman spectra obtained for a nanograined ceramic with an average grain size of 35 nm revealed a tetragonally distorted pure BaTiO3 phase showing a diffused phase transition behaviour with respect to temperature. Abnormality of phonon damping characteristics for the nanograined ceramic was demonstrated through comparison with powders with various crystallite sizes and the micrograined ceramic. The Curie temperature of the nanograined ceramic was estimated to be 105 °C from the temperature characteristic of a sharp peak at 307 cm−1, which is one of the most specific tetragonal features for bulk BaTiO3. In the present study, local stabilization of the tetragonal phase in ultra‐fine grains was experimentally demonstrated from comparison between the Raman spectroscopic results for powders and ceramics prepared through microemulsion‐mediated synthesis. Rather long phonon mean free paths can exist even in such ultra‐fine grains, but the phonon characteristics originating from various grains are diffused mainly because of the effect of internal stress. Copyright © 2007 John Wiley & Sons, Ltd.
Macroporous gels prepared at subzero temperatures as novel materials for chromatography of particulate‐containing fluids and cell culture applications
Authors: Plieva Fatima M. , Galaev Igor Yu. , Mattiasson Bo
Published: June 2007

Macroporous gels (MGs) with a broad variety of morphologies are prepared using the cryotropic gelation technique, i. e. gelation at subzero temperatures. These highly elastic hydrophilic materials can be produced from practically any gel‐forming system with a broad range of porosity extending from elastic and porous gels with pore sizes up to 1.0 μm to elastic and sponge‐like gels with pore sizes up to 100 μm. The versatility of the cryogelation technique is demonstrated by use of different chemical reactions (hydrogen bond formation, chemical cross‐linking of polymers, free radical polymerization) mainly in an aqueous medium. Appropriate control over solvent crystallization (formation of solvent crystals) and rate of chemical reaction during the cryogelation allows the reproducible preparation of cryogels with tailored properties. Different approaches, such as chemical modification of reactive groups, grafting of the pore surface with an appropriate polymer, or direct copolymerization with functional monomers are used for control of the surface chemistry of MGs. Typically, MGs with pore sizes up to 1.0 μm are produced in the shape of beads and MGs with pore size up to 100 μm are prepared as monoliths, discs, and sheets. The difference in porous structure of MGs defines the main applications of these porous materials. Elastic beaded MGs are mostly used as carriers for cell and enzyme immobilization or for capture of low‐molecular weight targets from particulate‐containing fluids in expanded‐bed mode. However, the elastic and sponge‐like MG monoliths with interconnected pores measuring hundreds of μm have been successfully used as monolithic columns for chromatography of particulate‐containing fluids (crude cell homogenates, viruses, whole cells, wastewater effluents) and as three‐dimensional scaffolds for mammalian cell culture applications.
Opposite effects of internal globus pallidus stimulation on pallidal neurones activity
Authors: Pralong Etienne , Pollo Claudio , Villemure Jean‐Guy , Debatisse Damien
Published: June 2007

Besides clinical efficacy, the mechanisms of action of deep brain stimulation (DBS) are still debated. To shed light on this complex issue, we have taken the opportunity to record the response of globus pallidus internus (GPi) neurones to 100 Hz stimulations in a case of Lesch–Nyhan syndrome (LNS) where four pallidal electrodes were implanted. Three types of response were observed, 2/19 neurones were unaffected by DBS. About 7/19 neurones were inhibited during DBS stimulation and 10/19 neurones were excited during DBS stimulation. Both effects ceased when DBS was turned off. Inhibited neurones were situated lower that exited ones on the trajectory (1.25 and 4.65 mm above the center of GPi respectively). These observations suggest that locally DBS induces a reversible inhibition of neurone firing rate while at the same time distantly exciting the main afferents to and/or efferents from the GPi. Both actions would result in a strong GPi inhibition that does not preclude increased outflow from the GPi. © 2007 Movement Disorder Society
Tamoxifen induces masculinization of genetic females and regulates P450 aromatase and müllerian inhibiting substance mRNA expression in Japanese flounder (Paralichthys olivaceus)
Authors: Kitano Takeshi , Yoshinaga Norifumi , Shiraishi Eri , Koyanagi Takashi , Abe Shin‐Ichi
Published: June 2007

Japanese flounder, Paralichthys olivaceus, provides an excellent model to elucidate the roles of sex steroid hormones in gonadal sex differentiation because the sex is easily altered by sex steroid treatments or water temperature control during the sex differentiation. We have previously shown that high water temperature, an aromatase inhibitor (fadrozole), or 17α‐methyltestosterone treatment causes the sex‐reversal from genetic females to phenotypic males and suppression of mRNA expression of ovary‐type P450 aromatase (P450arom), which is a steroidogenic enzyme responsible for the conversion of androgens to estrogens, in Japanese flounder. In the present study, we demonstrate that treatment of the genetic females with anti‐estrogen (tamoxifen) leads to their masculinization, suppresses P450arom mRNA expression, and induces mRNA expression of Müllerian inhibiting substance (MIS), a member of the transforming growth factor‐β (TGF‐β) superfamily, while it has no effect on mRNAs expression of estrogen receptor‐α (ERα) and ERβ. In contrast, 17β‐estradiol counteracted masculinization of the genetic females by tamoxifen or high water temperature treatment, up‐regulated P450arom mRNA expression, and down‐regulated MIS mRNA expression. These results strongly suggest that estrogen signaling through ERs dramatically influences the gonadal sex differentiation by regulating P450arom and MIS mRNA expression. Mol. Reprod. Dev. 74: 1171–1177, 2007. © 2007 Wiley‐Liss, Inc.
Antocholinergics in patients with overactive bladder: Assessment of ambulatory urodynamics and patient perception
Authors: Oh Seung‐June , Son Hwancheol , Jeong Jeong Yun , Ku Ja Hyeon
Published: June 2007

Aims

The aim of this study was to evaluate whether ambulatory urodynamic monitoring (AUM) may reflect patient perception of bladder condition and treatment benefit in patients with overactive bladder (OAB).

Methods

A total of 33 women and 7 men 23 to 72 years old who were undergoing AUM were included in this study. At baseline, patients were asked to complete the following information in the micturition chart for 3 consecutive days. Patients were given anticholinergics once daily for the 2 weeks. Two weeks after the treatment, all patients received an identical repeat study.

Results

Most parameters of AUM, micturition chart and patient perception were improved 2 weeks after treatment. However, when Spearman correlation coefficients were performed, all AUM parameters did not correlate with patient perception of bladder condition after treatment although some AUM parameters regarding incontinence were associated with patient perception of bladder condition at baseline. In addition, when patients were divided as the ‘no or some benefit’ group (n = 25) and the ‘much benefit’ group (n = 15), all AUM parameters except total voided volume (P = 0.004) were not significantly different in the two groups.

Conclusions

Because patients with pelvic floor dysfunction have widely varying expectations from treatment, the patient's goal for treatment is highly subjective. Our findings suggest that AUM does not take into account the patient perception of disease severity, and correlations between the patient view of treatment outcome and objective measures are poor. Therefore, strategies for assessing OAB should incorporate self‐perceived disease condition. Neurourol. Urodynam. 26:789–793, 2007. © 2007 Wiley‐Liss, Inc.
From expert opinion to evidence‐based: changes in the gold standard of primary brain tumour diagnosis
Authors: Kros JM
Published: June 2007

Since 1997, significant progress has been made in the WHO guidelines for the diagnosis of primary tumours of the central nervous system. A large group of international experts was involved in editing the content; consensus on definitions and classifications was sought; and updated findings of genomic investigations were included. Nevertheless, significant inter‐observer variability still exists in the histopathological diagnosis of several tumour types. The challenge for the near future is to identify histological and genotypic characteristics with prognostic or predictive value. With that aim, testing histological or molecular parameters in prospective clinical studies is indicated. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Segmentierte Mikrochip‐Falle für kalte Ionen
Authors: Schulz Stephan , Schmidt‐Kaler Ferdinand
Published: June 2007

Die Speicherung von kalten Ionenkristallen in einer Paul‐Falle gilt als ein erfolgversprechender Ansatz für die experimentelle Realisierung eines zukünftigen Quantencomputers. Nachdem das Funktionsprinzip für eine geringe Anzahl Ionen demonstriert werden konnte, steht nun die Skalierbarkeit dieser Methode auf eine große Zahl von Ionen im Brennpunkt der Forschung. Unsere Gruppe an der Universität Ulm hat kürzlich eine mikroskopische und in eine Vielzahl von Segmenten aufgeteilte Paul‐Falle gebaut.
Die Ramsey‐Methode in der Präzisions‐Massenspektrometrie
Authors: George Sebastian , Blaum Klaus , Kretzschmar Martin , Schweikhard Lutz
Published: June 2007

Jedes Atom ist auf einzigartige Weise durch seine Masse und damit die Bindungsenergien in Kern und Hülle charakterisiert. Durch die Verwendung der Ramsey‐Methode ist es kürzlich gelungen, bei gleichbleibender Genauigkeit eine Messzeitreduzierung von einer Größenordnung zu erreichen. Damit werden Präzisionsmassenmessungen an sehr kurzlebigen Kernen möglich.
Formschinken à la de Gennes
Authors: Vilgis Thomas
Published: June 2007

Mit dem Begriff Formschinken verbinden die meisten Menschen nichts Gutes. Das muss aber nicht sein. Außerdem hat Formschinken viel mit Physik und biophysikalischer Klebetechnik zu tun. Wir ergründen und genießen die Physik an einem selbst geformten Petersilienschinken, der sich auf französisch vornehmer “jambon persillé” nennt.
Comparative proteomic study of acute pulmonary embolism in a rat model
Authors: Li Sheng‐qing , Qi Hao‐wen , Wu Chang‐gui , Zhang Xiao‐jun , Yang Shu‐guang , Zhao Xin , Wu Zhe , Wang Yu , Que Hai‐ping , Liu Shao‐jun
Published: June 2007

Pulmonary embolism (PE) is a common, potentially fatal disease, whose blood clots originate from the deep venous system of the lower extremities. PE is of clinical importance because of the considerable mortality and morbidity. In this study, at first we established a rat PE model by injecting 3–4 emboli into the left jugular vein. Before collecting the lung tissues, we perfused them with saline through the right jugular vein and at the same time cut off the right carotid to remove the blood. Then we separated and identified differentially expressed proteins in lung tissues at different time points using the techniques of 2‐DE and MS. After image analysis of 2‐DE gels, 46 protein spots of interest were excised from the gels and identified by MALDI‐TOF‐MS. Thirty‐two protein spots of them found their corresponding protein candidates in the database. These proteins are associated with distinct aspects of PE such as the contractive function of smooth muscles, metabolism of energy, collagen and toxicant, cellular differentiation, apoptosis and injury, blood pressure adjustment, maintaining of acid–base balance, and so on. Ten of the identified proteins were validated by semiquantitative RT‐PCR, and three of them were further validated by Western blot analysis. The differential expression patterns of these proteins suggest the distinct roles they may play in different stages of the rat PE model, and information from this study may be helpful to uncover the pathophysiologic molecular mechanisms involved in PE.
Effects of non‐invasive pressure support ventilation (NI‐PSV) on ventilation and respiratory effort in very low birth weight infants
Authors: Ali Nabeel , Claure Nelson , Alegria Ximena , D'Ugard Carmen , Organero Roberto , Bancalari Eduardo
Published: June 2007

Background

Nasal continuous positive airway pressure (NCPAP) is used to provide support to non‐intubated infants, but it often fails. Pressure support ventilation (PSV) is a mode of synchronized ventilation that can supplement the spontaneous breathing effort, but it is unknown if it is effective in non‐intubated very low birth weight (VLBW) infants.

Objectives

To compare the acute physiological effects of non‐invasive PSV (NI‐PSV) versus NCPAP on tidal volume (VT), minute ventilation (VE), gas exchange, breathing effort, and chest wall distortion in VLBW infants.

Methods

Stable preterm infants of birth weight less 1,250 g were studied during consecutive 2 hr periods of NCPAP and NI‐PSV in random sequence. VT, VE, and thoraco‐abdominal synchrony were measured using respiratory inductance plethysmography. Breathing effort was measured by esophageal manometry. Gas exchange was measured by pulse oximetry and transcutaneous PCO2.

Results

Fifteen infants of birth weight (mean ± SD) 808 ± 201 g and 25.9 ± 1.8 weeks gestational age were studied while on NCPAP 5.3 ± 0.6 cm H2O and on NI‐PSV with 7.9 ± 1.3 cm H2O above NCPAP of pressure support. There were no differences in VT, VE, PCO2 or hypoxemia episodes. Peak and minute inspiratory effort were significantly reduced in NI‐PSV mode as compared to NCPAP. There was a significant reduction in indices of chest wall asynchrony in NI‐PSV mode.

Conclusion

When compared to NCPAP, NI‐PSV did not increase minute ventilation, but it effectively unloaded the patient's respiratory pump as indicated by a lower inspiratory effort and reduced chest wall distortion. Pediatr Pulmonol. 2007; 42:704–710. © 2007 Wiley‐Liss, Inc.
Defects in N+ion‐implanted ZnO single crystals studied by positron annihilation and Hall effect
Authors: Brauer G. , Anwand W. , Skorupa W. , Kuriplach J. , Melikhova O. , Cizek J. , Prochazka I. , von Wenckstern H. , Brandt M. , Lorenz M. , Grundmann M.
Published: June 2007

High quality ZnO single crystals of dimensions 10 x 10 x 0.5 mm3, grown by a hydrothermal approach, have been implanted by 40 keV N+ions to a fluence of 1 x 1015cm–2at room temperature. Their properties revealed by positron annihilation and Hall effect measurements are given in the as‐grown and as‐irradiated states, and after post‐implantation annealing in an oxygen ambient at 200 °C and 500 °C. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tunnel detrapping of self‐trapped positronium in SrF2 single crystal
Authors: Bondarev I. V. , Inoue K. , Suzuki N. , Hyodo T.
Published: June 2007

We develop a model to explain the temperature dependence of the delocalized Ps fraction in SrF2. The model accounts for both classical and tunnel detrapping mechanisms. We show that it is this model that reproduces the available experimental data well throughout the entire temperature range, thus demonstrating an important role of the temperature activated tunnel detrapping for the self‐trapped Ps in SrF2. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Applications of positron annihilation to dermatology and skin cancer
Authors: Liu Guang , Chen Hongmin , Chakka Lakshmi , Gadzia Joseph E. , Jean Y. C.
Published: June 2007

Positronium annihilation lifetime experiments have been performed to investigate the interaction between skin cancer and positronium for human skin samples. Positronium annihilation lifetime is found to be shorter and intensity is found to be less for the samples with basal cell carcinoma and squamous cell carcinoma than the normal skin samples. These results indicate a reduction of free volume in the molecular level for the skin with cancer with respect to the skin without cancer. Positron annihilation spectroscopy may be potentially developed as a new noninvasive and external method for dermatology clinics, early detection of cancer, and nano‐PET technology in the future. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Verifying the RTE model: ortho‐positronium lifetime measurement on controlled pore glasses
Authors: Thraenert S. , Hassan E. M. , Enke D. , Fuerst D. , Krause‐Rehberg R.
Published: June 2007

In porous media, the vacuum lifetime of ortho‐positronium (o‐Ps) of τ = 142 ns can be reduced markedly by pick‐off annihilation (interaction with electrons of the host material). So the o‐Ps lifetime is determined by the pore size which can be extracted by utilising approved models like the Tao‐Eldrup model for pore sizes smaller than 1 nm and the Tokyo model or RTE model for larger pore sizes. The RTE model contains an explicit temperature dependence of the o‐Ps lifetime. Experiments on controlled pore glasses (CPG) with different pore sizes (2‐70 nm) at different temperatures (50‐500 K) were performed to verify the RTE model. A general agreement for T = 300 K could be found. The temperature dependence of the lifetime, especially for low temperatures, could not be approved sufficiently. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantitative chemical analysis of vacancy‐solute complexes in metallic solid solutions by coincidence Doppler broadening spectroscopy
Authors: Folegati P. , Dupasquier A. , Ferragut R. , Iglesias M. M. , Makkonen I. , Puska M. J.
Published: June 2007

Low background measurements of 1D momentum spectra of the positron annihilation radiation by the coincidence Doppler broadening (CDB) method are currently used to obtain the quantitative chemical analysis of the environment of vacancy‐like defects in supersaturated solid solution of metals. Fractional concentrations are obtained by fitting the CDB spectra with linear combination of reference spectra. Examples regarding Al‐based alloys are presented to show the quality of the fitting and the consistency of the CDB analysis with positron lifetime measurements. The appropriate choice of the references is considered a key factor for reducing systematic errors. Nevertheless the method still awaits a theoretical validation. Preliminary first‐principles calculations regarding Cu‐decorated vacancies in aluminium are presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Small accelerator based intense positron beam sources
Authors: Weber M. H. , Pilant L. , Lynn K. G.
Published: June 2007

In order to progress positron and antimatter related research, it is highly desirable to develop options for intense sources of positrons capable of fueling positron beams with >107 positrons/sec. At the Center for Materials Research at Washington State University, we are investigating 13N as a positron source based on the nuclear reaction 12C(d,n)13N. Based on cross section data and earlier tests a source activity of about 11 mCi per μA of 3 MeV deuterons can be achieved. At 300 μA a 3 (4) MeV Van de Graaff accelerator will generate 1.2 (2.0) × 1011 positrons/sec in a graphite target. Several methods of utilizing this production rate for moderated positron beams have been tried. These include single crystal CVD diamond, high and low density graphite, frozen source gases, tungsten foil moderation and solid gas moderation. To date, the most successful approach yielded ∼105 moderated positrons per second – efficient moderation of the source flux has not been accomplished. We will present the current status and discuss possible reasons for the poor performance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of hydrogen peroxide treatment on Au/n‐ZnO contact
Authors: Chen X. D. , Gu Q. L. , Ling C. C. , Brauer G. , Anwand W. , Skorupa W. , Reuther H. , Djurišić A. B.
Published: June 2007

The Au/n‐ZnO contact behavior was investigated as a function of hydrogen peroxide pre‐treatment of the ZnO sample by current‐voltage (IV) measurement. The change from non‐rectifying to rectifying performance upon etching was discussed in connection with sample characterization by positron annihilation spectroscopy (PAS), Auger electron spectroscopy (AES) and scanning electron microscopy (SEM). It was concluded that the gain of the rectifying property was properly associated with the formation of a defective interfacial region at the Au/n‐ZnO contact. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermalization of positronium in helium
Authors: Engbrecht J. , Kolan A. , Johnson C. , Legard A. , Lund S.
Published: June 2007

A new Age‐Momentum Correlation apparatus has been built for the purpose of studying Positronium‐Gas scattering. This apparatus uses a HPGe detector to perform time‐resolved Doppler Broadening Studies on positronium in a gas environment. With this information, the thermalization process can be studied by observing the energy as a function of time. Modelling the rate of thermalization can then be used to extract a momentum transfer cross‐section. Improved data rate and energy resolution over previous measurements that used Doppler broadening methods have been obtained. More importantly, the simultaneous acquisition of both time and energy spectra allow for systematic checks that were not available to previous experiments. Preliminary results are presented. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of the surface and volumetric positron techniques for the assessment of material damage in operational conditions
Authors: Urban‐Klaehn Jagoda , Ritchie Scott , Hunt Alan W.
Published: June 2007

Positron Systems, Inc. applies surface and volumetric positron techniques to investigate damage in metal components in operational conditions. The width and shape of Doppler Broadening gamma peak (S‐parameter) is used for defect analysis. Two techniques are commonly used: the Induced Positron Analysis ‐ Surface technique (IPA‐S) to investigate a surface and near‐surface effects and the Induced Positron Analysis‐ Volumetric technique (IPA‐V) that penetrates through the volume of the examined materials. Positron Annihilation measurements have been successfully performed in many applications. Presented below are cases demonstrating successful applications in assessing damage in gas generator fuel injector stems, aerospace parts that underwent strain and fatigue treatment, and residual stress effects in shot‐peened specimens and steel plates with cracks. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Resolution deconvolution method applied to 2D‐ACAR measurements
Authors: Chiba T. , Toyama T. , Nagai Y. , Hasegawa M.
Published: June 2007

An inexpensive way to achieve high resolution 2D‐ACAR measurements is to utilize resolution deconvolution techniques. We developed a resolution deconvolution method which avoids noise amplification and is applicable to the 3D reconstruction method using Fourier‐Bessel transforms. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fermi surface of ErGa3
Authors: Kontrym‐Sznajd G. , Samsel‐Czekała M. , Grechnev G. E. , Sormann H.
Published: June 2007

The Fermi surface (FS) in paramagnetic ErGa3 is estimated by various band structure methods: linear muffin‐tin orbital (LMTO) in the atomic sphere approximation (ASA) and three new codes contained full potential (FP) instead of ASA, namely FP‐LMTO, FP linear augmented plane wave (FLAPW), and FP local orbitals (FPLO) methods. Three dimensional (3D) electron‐positron (e‐p) momentum densities ρ (p) are reconstructed from two dimensional (2D) angular correlation of annihilation radiation (ACAR) spectra measured for paramagnetic ErGa3. Reconstructed densities in the extended p‐space, folded into the reduced k‐space, are compared with the theoretical results. Unfortunately, none of these modern FP codes is able to give satisfying description of the experimental data that are in perfect agreement with previous LMTO‐ASA results. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Composition dependence of positron annihilation lifetime for Al‐Pd‐Re‐Ru quasicrystal and 2/1‐AlPdRu approximant crystal
Authors: Takagiwa Y. , Kobayashi J. , Matsushita Y. , Kanazawa I. , Nagata T. , Kimura K. , Kobayashi Y.
Published: June 2007

Quaternary icosahedral Al‐Pd‐Re‐Ru (i ‐Al71Pd20(Re1–xRux)9 (X = 0.4, 0.55, 0.7, 0.85)) quasicrystals and its 2/1‐AlPdRu approximant crystal, 2/1‐Al71Pd20Ru9, were investigated by positron annihilation lifetime spectroscopy. The positron annihilation lifetimes measured here are significantly longer than those of defect‐free states estimated by compositionally weighting the constituent elements. This result suggests that high densities of structural vacancies exist in both i ‐Al‐Pd‐Re‐Ru quasicrystals and 2/1‐AlPdRu approximant crystal. For i ‐Al‐Pd‐Re‐Ru quasicrystals, composition dependence of the positron annihilation lifetime is compared with that of the electrical conductivity. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The investigation of swollen process in gelatin gel by using positron annihilation spectroscopy
Authors: Akiyama Yoko , Shibahara Yuji , Takeda Shin‐ichi , Izumi Yoshinobu , Honda Yoshihide , Nishijima Shigehiro
Published: June 2007

The change of free volume hole radius and bound state of water in the biopolymer gel swollen with water were investigated by positron annihilation lifetime spectroscopy (PALS) and differential scanning calorimetry (DSC). In this study, gelatin with multiple helix structure of polypeptide (MW ∼100,000) was used as biopolymer. To examine into bound state of water in gelatin gel, the weight percentage of freezing and non‐freezing water against total water in gelatin gels were calculated from fusion enthalpy of DSC curves. Accompanied with the increase of gelatin concentration, the percentage of non‐freezing water increased while that of freezing water decreased, and above 60%(w/w) of gelatin concentration, percentage of non‐freezing water reached approximately 100%(w/w). Since the change in bound state of water results from network structure of gelatin gel, free volume hole radius of gelatin gels with different concentrations were characterized from positron annihilation lifetime spectra using PATFIT‐88 program. The lifetime of o‐Ps became longer or the size of free volume hole increased accompanied with the increase of water content. It is considered that the hydrophilic sites, carboxyl groups in gelatin molecules, locate inside of the helix and hydrophobic groups locate outside of the helix. This means that once the water molecules penetrate into the gelatin network, they are attracted by carboxyl groups inside the helix structure and the hydrogen bonds are formed between water and carboxyl groups. The water molecules localized inside the helix expand the helix surface outward by the thermal motion, leading to the increase of free volume hole radius. This idea assumes localization of positrons in the vicinity of the hydrophilic group and the influence of local potential on lifetimes of positron and positronium. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron states in polypropylene and polystyrene at low temperature
Authors: Djourelov N. , Dauwe C. , Palacio C. A. , Laforest N. , Bas C.
Published: June 2007

The increase of the positronium (Ps) yield as a function of the positron (e+) source exposure time at 20 K was monitored in polypropylene and polystyrene by positron annihilation lifetime (PAL) and Doppler broadening (DB) spectroscopy. The contributions of the different e+ and Ps states as extracted from the PAL analysis were used to reproduce the behaviour of the sharpness parameter (S) as a function of the wing parameter (W) of the annihilation line as measured by DB spectroscopy. We find a remarkable non‐linearity in the S ‐W plots, which seems to be related to the existence of a third component (C3) in a four‐component exponential analysis. We discuss the origin of C3 in the frame of a “blob” analysis of the PAL spectra. It is shown that the simulated S‐W dependence can satisfactorily fit the observed non‐linearity only on the assumption that C3 characterizes a e+‐molecule complex. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A PALS and DSC study on SBR/NR blends
Authors: Salgueiro W. , Somoza A. , Consolati G. , Quasso F. , Marzocca A.
Published: June 2007

A PALS study on the behaviour of the o‐Ps lifetime with the vulcanization temperature for styrene butadiene rubber (SBR), natural rubber (NR) and a SBR/NR blend was carried out. These elastomers were characterized by means of torque curves in a rheometer. From these measurements the time to get the maximum torque (t100) for each sample was determined. The specimens investigated were cured at 433 K during a time t100. Using DSC and PALS techniques, the glass transition temperatures (Tg) for the elastomers mentioned were obtained. The results are discussed in comparison to those obtained studying pure SBR and NR samples, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural characterization and porosity analysis in spin coated silica thin films as gas selective membranes
Authors: Mariazzi S. , Patel N. , Toniutti L. , Checchetto R. , Miotello A. , Brusa R. S.
Published: June 2007

Microporous silica films with thickness in the 200 nm range, were deposited by spin coating technique on (111) oriented n‐Si substrate changing the acid and water concentration in the sol solution and by the inclusion of porogen (polyvinylpyrrolidone). We have investigated how the different silica sol preparation can affect the structure and porosity of the thermally annealed thin films. The structural characterization was carried out by Fourier Transform Infrared Spectroscopy while the porosity was studied by 3γ‐annihilation of ortho‐positronium (o‐Ps) and Doppler broadening of the positron annihilation line. Infrared spectroscopy and positron annihilation spectroscopy show that thermal annealing at temperatures higher than 400 °C gives rise to a progressive reconstruction of the SiO2microstructure and an increase of the nanopores size as shown byo‐Psformation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ratio of positron annihilation into three photons versus two
Authors: Pevovar S. C. , Weber M. H. , Lynn K. G.
Published: June 2007

Rare and exotic annihilations of free positrons have been investigated extensively since the first discovery of positrons. The annihilation into three photons, however, has been neglected following theoretical work by Øre and Powell and several experimental studies using radioactive sources. Øre and Powell predicted that only one in 372 annihilations would result in the emission of three photons due to the parallel spin alignment of the electron‐positron pair. A number of approximations were made to make the calculation tractable most notably the assumption of low momentum. No material dependence was expected. Subsequent experiments showed some dependence on material properties, notably on Z and density. We have set up an experiment to measure the annihilation into two and three photons with a five detector coincidence technique. Our results for low Z targets of Kapton, silicon and carbon, indicate no material dependence. The simplicity of the experiment and the high sensitivity for three photon annihilations render this method suitable for the characterization of porosity particularly when the concentration of pores is small. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
RFID research and testing for packages of apparel, consumer goods and fresh produce in the retail distribution environment
Authors: Singh S. P. , McCartney M. , Singh J. , Clarke R.
Published: June 2007

Radio frequency identification (RFID) is a term used for any device that can be sensed at a distance by radio frequencies with few problems of obstruction. The origins of the term lie in the invention of tags that reflect or retransmit a radio‐frequency signal. According to a recent article by Forrester Research, the minimal ‘Slap and Ship’ approach to RFID compliance will cost an individual company between $2 million and $20 million. Because retailers like Wal‐Mart plan to share with their suppliers all the RFID‐generated data points (from when a case/pallet enters their distribution centre until it leaves their stockroom), suppliers will eventually be able to use this data as a powerful forecasting tool. RFID is an enabling technology that can potentially facilitate a real‐time, end‐to‐end supply chain visibility system. Suppliers who integrate full‐scale RFID systems will realize efficiencies in time, material movement, inventory planning, shipping and warehousing both internally and externally. This paper provides a brief overview of the RFID technology, mandates by retailers and federal agencies, advances towards global standardization and typical consumer level RFID applications, and discusses RFID initiatives taken by some of the global leaders in apparel, consumer goods and fresh produce industries. Copyright © 2007 John Wiley & Sons, Ltd.
Molecular transport characteristics of poly (ethylene‐co‐vinyl acetate) membranes in the presence of normal alkanes
Authors: Anilkumar S. , Thomas Sabu
Published: June 2007

Solvent transport into poly (ethylene‐co‐vinyl acetate) membranes exposed to n‐alkanes has been studied in the temperature interval of 30–60°C. Pure and cross‐linked membranes were prepared. Membranes with different loading of cross‐linking agent were also prepared. It was found that for all liquids, the equilibrium penetrant uptake was influenced by the introduction of cross links. The mechanism of transport has been found to deviate from the regular Fickian behaviour. Transport parameters such as diffusion coefficient, sorption constant and permeability coefficient have been calculated. The influence of temperature on transport was analysed. Transport parameters and activation parameters for the process of diffusion have been calculated. The transport coefficients and the activation parameters showed a dependence on cross‐link density. The Van't Hoff's relationship was used to compute the entropy change. The values of polymer–solvent interaction parameters have been used to calculate the molar mass between cross links of the network polymer. The phantom and affine models were used to analyse the deformation of the networks during swelling. A correlation between theoretical and experimental results was also done. Copyright © 2007 John Wiley & Sons, Ltd.
Alpine gravity waves: Lessons from MAP regarding mountain wave generation and breaking
Authors: Smith Ronald B. , Doyle James D. , Jiang Qingfang , Smith Samantha A.
Published: June 2007

The two‐month special observing period of the Mesoscale Alpine Programme (MAP) in autumn 1999 included a variety of complex mountain wave events. Seven wave events were carefully analyzed, compared with numerical models and described in published papers. These detailed investigations revealed some common dynamical elements, i.e. the importance of low‐level processes involving the slow‐moving boundary layer, low‐level wind shear causing either wave absorption or decoupling/spilling, upstream blocking, and latent heat release. Based on these studies, it is clear that any quantitative prediction of mountain wave generation must take full account of these lower troposphere processes. The newest numerical models show significant skill in simulating these effects. Using these models, the climatology of waves over the Alps can be studied. Copyright © 2007 Royal Meteorological Society
An iterative time‐stepping scheme for the Met Office's semi‐implicit semi‐Lagrangian non‐hydrostatic model
Authors: Diamantakis Michail , Davies Terry , Wood Nigel
Published: June 2007

A predictor–corrector time‐stepping algorithm is used by the Met Office's semi‐implicit semi‐Lagrangian non‐hydrostatic Unified Model. This scheme is here extended to include an iterative option, improving performance when large time steps are used in highly nonlinear situations. The scheme is described, and results from global model tests, which show improvements in forecast accuracy, are presented. Copyright © 2007 Royal Meteorological Society
Hydrological aspects of the Mesoscale Alpine Programme: findings from field experiments and simulations
Authors: Ranzi Roberto , Zappa Massimiliano , Bacchi Baldassare
Published: June 2007

The Mesoscale Alpine Programme (MAP) was a unique initiative to improve the understanding of processes involved in orographically influenced precipitation events and in the related emergence and mitigation of floods in the Alps. This study presents a summary of the results from investigations of hydrological relevance in areas to the south (Lago Maggiore watershed) and north (Ammer watershed) of the Alps. A special focus is given to the 1999 Special Observing Period (SOP) experiment. MAP has been an important dialogue platform between the hydrological and meteorological communities. A common goal has been the verification and the assessment of errors and sources of uncertainty of new coupled techniques for flood forecasting in mountainous environments. The ensemble multi‐model error in the hydrometeorological forecast, two days in advance, was 30% of the observed peaks and 15% of the observed runoff volumes, on average. To provide some insight on the relative importance and priority of observation strategies of hydrological factors such as soil moisture and reservoir volume in contributing to the flood intensity, the MAP project ‘Hydrology’ focused also on the role and magnitude of water storage in reservoirs. The presented analyses indicate that for the investigated basins and flood events, the storage reservoirs may retain, on average, up to 10% of the event runoff volume and are key elements contributing to the mitigation of peak runoff. The observed variability of soil moisture is large and therefore it has been confirmed that severe difficulties remain in instrumental monitoring of soil moisture in mountainous environments. The sensitivity of floods to soil moisture in the physio‐geographic context analysed here seems, however, to be minor, due to the shallow soil layer covering the underlying rocks and the relatively high permeability of soils which reduce the ‘hydrological memory’ of the soil cover in the mountain basins investigated. Copyright © 2007 Royal Meteorological Society
Föhn in the Rhine Valley during MAP: A review of its multiscale dynamics in complex valley geometry
Authors: Drobinski Philippe , Steinacker Reinhold , Richner Hans , Baumann‐Stanzer Kathrin , Beffrey Guillaume , Benech Bruno , Berger Heinz , Chimani Barbara , Dabas Alain , Dorninger Manfred , Dürr Bruno , Flamant Cyrille , Frioud Max , Furger Markus , Gröhn Inga , Gubser Stefan , Gutermann Thomas , Häberli Christian , Häller‐Scharnhost Esther , Jaubert Geneviève , Lothon Marie , Mitev Valentin , Pechinger Ulrike , Piringer Martin , Ratheiser Matthias , Ruffieux Dominique , Seiz Gabriela , Spatzierer Manfred , Tschannett Simon , Vogt Siegfried , Werner Richard , Zängl Günther
Published: June 2007

This paper summarizes the findings of seven years of research on föhn conducted within the project ‘Föhn in the Rhine Valley during MAP’ (FORM) of the Mesoscale Alpine Programme (MAP). It starts with a brief historical review of föhn research in the Alps, reaching back to the middle of the 19th century. Afterwards, it provides an overview of the experimental and numerical challenges identified before the MAP field experiment and summarizes the key findings made during MAP in observation, simulation and theory. We specifically address the role of the upstream and cross‐Alpine flow structure on föhn at a local scale and the processes driving föhn propagation in the Rhine Valley. The crucial importance of interactions between the föhn and cold‐air pools frequently filling the lower Rhine Valley is highlighted. In addition, the dynamics of a low‐level flow splitting occurring at a valley bifurcation between the Rhine Valley and the Seez Valley are examined. The advances in numerical modelling and forecasting of föhn events in the Rhine Valley are also underlined. Finally, we discuss the main differences between föhn dynamics in the Rhine Valley area and in the Wipp/Inn Valley region and point out some open research questions needing further investigation. Copyright © 2007 Royal Meteorological Society
On the boundary‐layer structure over highly complex terrain: Key findings from MAP
Authors: Rotach Mathias W. , Zardi Dino
Published: June 2007

Within MAP, one of the scientific projects was devoted to ‘Boundary Layers in Complex Terrain’. In a number of subprojects, boundary‐layer issues were addressed and detailed high‐resolution multi‐sensor observations were combined with simulation by models allowing for adequate parametrization of turbulence processes. In this contribution, the projects are briefly introduced and an attempt is made to summarize their key findings and to put them into a joint perspective. Spatial variability is found to be large but strictly related to topography and therefore allowing for possible parametrization. Traditional boundary‐layer scaling approaches cannot simply be applied over highly complex topography, but some of the MAP findings suggest the potential for suitable extensions of those scaling relations to cover various cases of complex terrain. The mean boundary‐layer structure and thermally driven flows in narrow valleys are found not to be generally in line with previous results from larger valleys elsewhere. Furthermore, local circulations are reported to contribute considerably to exchange between valley and free troposphere. In particular, the range of their effects on the lower atmosphere seems to be larger than just turbulent transport within the planetary boundary layer would suggest. Thus in larger‐scale numerical models where the topography is not resolved, possible sub‐grid parametrizations for local exchange seem to be in order. Copyright © 2007 Royal Meteorological Society