bluuebunny/crossref_metadata_2025 huggingface dataset:
G‐Probe‐1 ‐ An International Proficiency Test for Microprobe Laboratories ‐ Report on Round 1 : February 2002 (TB‐1 Basaltic Glass)
Authors: Potts Philip J. , Thompson Michael , Wilson Stephen
Published: May 2007

Results are presented for round one of a new international proficiency testing programme designed for microprobe laboratories involved in the routine analysis of silicate minerals. The sample used for this round was TB‐1, a basaltic glass fused and prepared by the USGS. Thirty nine laboratories contributed data to this round, the majority of major element results being undertaken by EPMA and the majority of trace elements by LA‐ICP‐MS. Assigned values were derived from the median of results produced by nine selected laboratories that analysed powdered material by conventional ICP‐MS, INAA and XRF techniques using bulk powders of the sample. Submitted microprobe results were evaluated using a target precision calculated using the Horwitz function, adopting the same criteria as those used for “applied” geochemistry laboratories in the companion GeoPT proficiency testing programme for laboratories involved in the routine bulk analysis of silicate rocks. An evaluation of results from participating microprobe laboratories indicated that overall, data were compatible with this precision function. A comparison between the performance of bulk and microprobe techniques used in the analysis of the basaltic glass showed remarkably good agreement, with significant bias only observed for the major oxide MgO.
Preliminary Results from a New 157 nm Laser Ablation ICP‐MS Instrument: New Opportunities in the Analysis of Solid Samples
Authors: Telouk Philippe , Rose‐Koga Estelle F. , Albarede Francis
Published: May 2007

Preliminary results are given from an excimer 157 nm laser ablation multiple‐collector inductively coupled plasma‐mass spectrometer (LA‐MC‐ICP‐MS), used for the isotopic measurements of solid materials. Elements of geological interest with different volatilities such as Pb and U (e.g. zircon geochronology) and Cu and Zn (as examples of geochemical/biochemical tracers) were analysed. The range of ablation rates of 20‐150 nm s‐1 enabled us to ablate the sample down to a depth of 45 μm for a 50 μm diameter pit. The Cu and Zn isotopic measurements gave values that were very stable with, on average, a 0.01 % standard error, comparable with that achieved in liquid mode measurements.
High Precision Ru, Pd, Ir, Pt, Re and REE Determinations in the Stevns Klint Cretaceous‐Tertiary Boundary Reference Material (FC‐1) by Isotope Dilution Multiple Collector Inductively Coupled Plasma‐Mass Spectrometry
Authors: Jensen Kristine Krogh , Baker Joel , Waight Tod , Frei Robert , Peate David W.
Published: May 2007

We present high precision Ir, Ru, Pt, Pd, Re and rare earth element (REE) determinations by isotope dilution multiple collector‐ICP‐MS on the Cretaceous‐Tertiary boundary sedimentary reference material FC‐1. Samples for platinum‐group element measurements were digested in Carius tubes followed by acid digestion. The platinum‐group elements were subsequently separated by anion exchange chemistry and determined by multiple collector‐ICP‐MS. The accuracy of the platinum‐group element analyses have been verified by comparative analyses of the reference materials WITS‐1 and GP13 (sample size 0.5‐1 g). Replicate analyses of FC‐1 (sample size 0.2 g) exhibit good reproducibility (RSD < 5%) for all the analysed platinum‐group elements. REE data also exhibit excellent reproducibility (RSD < 0.5%), which indicates that this sample is homogeneous for the determination of the platinum‐group elements and REE at the 0.2 g level.
Synthetic Silica Glass for Trace Aluminium Determination in Quartz by Electron Microprobe
Authors: Miyoshi Naoya , Satoh Hisao , Yamaguchi Yoshiaki , Masuda Harue
Published: May 2007

Five synthetic silica glasses have been prepared for microprobe determination of trace aluminium in quartz. The glasses were synthesized from tetraethoxysilane (TEOS) into which between 0 and 1431 μg g‐1 aluminium had been doped. The aluminium concentrations of the glasses were independently determined by ICP‐AES analysis. X‐ray wavelength shift in the Al Kα peak was minimised relative to unknown quartz samples when these glasses were used for calibration. A set of these five glasses yielded a linear calibration line, and are available for trace aluminium analysis of quartz in routine microprobe systems.
International Association of Geoanalysts’Protocol for the Certification of Geological and Environmental Reference Materials
Authors: Kane Jean S. , Potts Philip J. , Wiedenbeck Michael , Carignan Jean , Wilson Stephen
Published: May 2007

This protocol has been developed by the International Association of Geoanalysts to demonstrate procedures for the certification of geological and environmental reference materials to comply to the fullest extent possible with recommendations of the International Organisation for Standardisation (ISO Guide 35). A practical approach is described on the assumption that certifications will be normally be based on collaborative analysis programmes in which participating laboratories are preselected on the basis of performance in a proficiency testing programme or on the basis of other criteria of merit.
Three Cobalt‐Rich Seamount Crust Reference Materials: GSMC‐1 to 3
Authors: Wang Xiaohong , Gao Yushu , Wang Yimin , Andreev S.I.
Published: May 2007

A research project involving the preparation of three Co‐rich crust reference materials (GSMC‐1 to 3) has been preliminarily completed. The samples were collected from the eastern and central Pacific seamount zones and their main chemical composition is MnO2. After the raw materials were dried in ambient air and at low temperature (60‐100 C), they were ground in a ball mill to form a well‐mixed powder. The proportion of particle size fractions of < 74 μm and < 3 μm was over 98% and 50% respectively. The homogeneity of the materials was tested using wavelength dispersive X‐ray fluorescence spectrometry (WD‐XRF). The relative standard deviation (% RSD) of the measurements for all the selected elements in forty sub‐samples randomly taken from the bottles was less than 0.4%. Sixteen laboratories from Germany, Russia, France, Australia and China participated in the collaborative analysis programme. Fifty seven elements or constituents were analysed, and among those, forty six elements were certified in each sample. The sum of contents of the major and minor elements or components was 99.5% for GSMC‐1, 99.6% for GSMC‐2 and 99.2% for GSMC‐3.
Polyatomic Interferences Produced by Macroelements During Direct Multi‐Elemental ICP‐MS Hydrochemical Analysis
Authors: Epov Vladimir N. , Lariviere Dominic , Epova Ekaterina N. , Evans R. Douglas
Published: May 2007

An experimental study of the interferences produced by macroelements (Na, K, Ca, Mg, Sr, S, Cl, Si, N and C) contained in natural waters during inductively coupled plasma‐mass spectrometry (ICP‐MS) is presented. The most significant interferences created by these elements were found to be SO, CO, CAr, SiH, SiO, NaH, NaAr, MgAr, CaO, KO and KAr, the magnitude of which was dependant on the concentration of each macroelement. To reduce these interferences, different approaches, for example, desolvating nebulisation, high resolution and dynamic reaction cell ICP‐MS were applied and compared. All three approaches were found to be useful tools for significantly reducing various polyatomic interferences. Advantages and disadvantages for each approach are discussed.
Application of Atomic Spectrometric Methods Coupled with Gas Chromatography for Geochemical Exploration
Authors: Safronova Nataliya , Mazo Galina , Korobeinik Galina , Shepeleva Elena , Zhiltsova Ludmila
Published: May 2007

This paper presents a scheme of analysis for bottom sediments based on inductively coupled plasma‐atomic fluorescence spectrometry and arc discharge atomic emission spectrometry combined with instrumental pyrolysis and gas chromatographic methods (head space analysis) for determining organic matter. The experimental investigation was performed on bottom sediments of the Kuybyshev and Ivankovo reservoirs on the Volga River, used as a drinking water supply. The selective sample dissolution method followed by the inductively coupled plasma‐atomic fluorescence spectrometry liquid phase analysis and the arc discharge atomic emission spectrometry solid phase analysis was used to obtain quantitative information on heavy metal speciation in bottom sediments. In the present work we have taken the direct extraction scheme for analysis. It is shown that the proposed combination of instrumental methods is highly effective for revealing natural and anthropogenic components in the composition of organic matter, for conducting preliminary estimation of the binding of heavy metals with organic matter and for assessing activity of organic matter biochemical transformation. The proposed approach enlarges the capabilities for prediction and modelling of the processes in environmental‐geochemical investigations.
Geochemical Baselines of Nickel and Chromium in Various Surficial Materials in the Barents Region, NW Russia and Finland
Authors: Salminen Reijo , Bogatyrev Igor , Chekushin Victor , Glavatskikh Sergey P. , Gregorauskiene Virgilija , Niskavaara Heikki , Selenok Lubov , Tenhola Markku , Tomilina Olga
Published: May 2007

The geochemical baselines of nickel and chromium were studied from the data produced by the Barents Ecogeochemistry project, a large international regional geochemical mapping exercise. The project surveyed major and trace element distributions in stream water, organic and mineralogically‐modified soil horizons, and terrestrial moss in the northwestern part of Russia and in Finland. Other materials were collected during the pilot phase and later from thirty special sites. The results on respective materials by XRF, ICP‐MS and ICP‐AES showed that both geological and anthropogenic factors have an influence on the geochemical baseline concentrations of Ni and Cr in organic soil and stream water. The main explanation of the observed distribution patterns in terrestrial moss is human activity, but geological factors can also affect the baselines. The variation of geochemical baselines in the mineral‐rich soil horizon depends only on variations in bedrock. The mineralogy of samples mainly controls the leachability properties of soil samples.
Determination of Lithium Contents in Silicates by Isotope Dilution ICP‐MS and its Evaluation by Isotope Dilution Thermal Ionisation Mass Spectrometry
Authors: Moriguti Takuya , Makishima Akio , Nakamura Eizo
Published: May 2007

A precise and simple method for the determination of lithium concentrations in small amounts of silicate sample was developed by applying isotope dilution‐inductively coupled plasma‐mass spectrometry (ID‐ICP‐MS). Samples plus a Li spike were digested with HF‐HClO4, dried and diluted with HNO3, and measured by ICP‐MS. No matrix effects were observed for 7Li/6Li in rock solutions with a dilution factor (DF) of 97 at an ICP power of 1.7 kW. By this method, the determination of 0.5 μg g‐1 Li in a silicate sample of 1 mg can be made with a blank correction of < 1%. Lithium contents of ultrabasic to acidic silicate reference materials (JP‐1, JB‐2, JB‐3, JA‐1, JA‐2, JA‐3, JR‐1 and JR‐2 from the Geological Survey of Japan, and PCC‐1 from the US Geological Survey) and chondrites (three different Allende and one Murchison sample) of 8 to 81 mg were determined. The relative standard deviation (RSD) was typically < 1.7%. Lithium contents of these samples were further determined by isotope dilution‐thermal ionisation mass spectrometry (ID‐TIMS). The relative differences between ID‐ICP‐MS and ID‐TIMS were typically < 2%, indicating the high accuracy of ID‐ICP‐MS developed in this study.
Use of Chelating Resin YPA4Micro‐Columns for the On‐Line Preconcentration and Separation of Gold(III), Silver(I), Palladium(II) and Platinum(IV) in Geological and Environmental Samples and Their Determination by Inductively Coupled Plasma‐Atomic Emission Spectrometry
Authors: Wu Yiwei , Jiang Zucheng , Hu Bin
Published: May 2007

A simple and selective method of flow injection (FI) using a micro‐column packed with chelating resin YPA4as solid phase extractant was developed for the preconcentration and separation of trace amount of noble metals, Au(III), Ag(I), Pd(II) and Pt(IV), followed by ICP‐AES determination. In HNO3media, the chelating resin was selective towards Au(III), Ag(I), Pd(II) and Pt(IV), and the analysed ions were readily desorbed quantitatively with 5 ml of 2.5% m/v thiourea. Effects of acidity, sample flow rate and concentration, elution solution and interfering ions on the recovery of the analytes were systematically investigated. Under optimum conditions, the adsorption capacities of YPA4for Au(III), Ag(I), Pd(II) and Pt(IV) were 67.2, 43.1, 64.8 and 27.6 mg per gram of resin in HNO3media, respectively. It was found that YPA4could be used for more than eight runs in HNO3media without loss of capacity. The proposed method was used for the determination of trace noble metals in geological and environmental samples, and the analytical results obtained were in good agreement with the recommended values.
The Use of Multiple Reference Samples for the Monitoring of Ion Microprobe Performance During Zircon 207Pb/206Pb Age Determinations
Authors: Black Lance P.
Published: May 2007

Data from a series of extended analytical sessions using a range of different zircon reference samples have been used to investigate the periodic derivation of abnormal 207Pb/206Pb ages during microbeam analysis%For the Canberra SHRIMP II, this phenomenon probably results from the presence of a signal at mass 204 that is alien to the Pb spectrum; isotopic fractionation is unlikely to be a significant contributor. In contrast, abnormal 207Pb/206Pb ages obtained from SHRIMP I at the same research centre require a different, but as yet unknown explanation. Assessment of the reasons for atypical 207Pb/206Pb measurements and the means of correcting for them should therefore be independently assessed for individual analytical instruments. The use of reference samples with very different ages is an effective way of doing this, because older reference samples are more useful for documenting isotopic fractionation, whereas younger ones are more sensitive indicators of isobaric interference.
Determination of Lithium, Beryllium and Boron at Trace Levels by Laser Ablation‐Inductively Coupled Plasma‐Sector Field Mass Spectrometry
Authors: Tiepolo Massimo , Zanetti Alberto , Vannucci Riccardo
Published: May 2007

The analytical capabilities of laser ablation (LA)‐ICP‐MS in determining Li, Be and B at trace levels in geological samples have been tested on a series of glass reference materials and natural samples. The LA‐ICP‐MS instrument used consisted of a sector‐field ICP‐MS coupled with a laser ablation microprobe operating at either 266 or 213 nm wavelength. Reference glasses from NIST (SRM 612, 614 and 616) and MPI‐DING (KL2‐G, ML3B‐G, StHs6/80‐G, GOR128‐G, GOR132‐G, T1‐G and ATHO‐G) were selected to develop the analytical method and to assess the best instrumental configuration. A series of calcic amphiboles with different Li, Be and B concentrations were also analysed using both LA‐ICP‐MS and SIMS to test the applicability of the method to natural minerals. Results indicated that with a spot size of 40 μm the agreement between measured and reference values of Li, Be and B is generally better than 10% for NIST SRM 612 and 20% for NIST SRM 614. Average reproducibility at the 2s level was 10% for Li, 20% for Be and 15% for B. Limits of detection were approximately 100 ng g‐1 for Be and B and 200 ng g‐1 for Li. These results were confirmed by analyses carried out on natural amphiboles and compared well in terms of precision and accuracy with those commonly achieved by SIMS.
The Preparation and Characteristics of the Geochemical Certified Reference Material BEM (Emeishan Basalt)
Authors: Tong Chunhan , Zhou Sichun , Li Juchu , Liu Xiaohui , Wu Jianping
Published: May 2007

A basaltic certified reference material BEM, prepared by Chengdu University of Technology, has recently been approved as a Primary Grade Reference Material (GBW07126) by the General Administration of Quality Supervision, Inspection and Quarantine of China. BEM was sampled from the Emeishan Basalts in China, which is one of the largest basalt provinces in the world. After successfully completing homogeneity and stability tests, collaborative analyses were carried out in seventeen Chinese institutes and laboratories and two American laboratories. More than ten reliable analytical methods based on different principles of measurement were adopted, of which ICP‐MS, NAA and ICP‐AES contributed 60.5% of all results. Fifty‐four elements and oxide components were characterised as certified values, four elements as recommended values and nine elements as information values. A minimum sampling mass of 40 mg for most elements is recommended for use.
Complete Trace Elemental Characterisation of Granitoid (USGS G‐2, GSP‐2) Reference Materials by High Resolution Inductively Coupled Plasma‐Mass Spectrometry
Authors: Pretorius Wilma , Weis Dominique , Williams Gwen , Hanano Diane , Kieffer Bruno , Scoates James
Published: May 2007

The United States Geological Survey granitic and granodioritic reference materials G‐2 and GSP‐2 were decomposed in high‐pressure bombs using both HF‐HNO3 and HF‐HNO3‐HClO4 in order to evaluate the feasibility of characterising the entire suite of geologically relevant trace elements through direct analysis with a high‐resolution inductively coupled plasma‐mass spectrometer (HR‐ICP‐MS). The digested samples were diluted to the appropriate levels and analysed at low, medium and high resolution depending on the required sensitivity and potential interferences for each element. Memory effects during analysis of the high field strength elements (HFSE) were negligible when analysed using an all‐Teflon, uncooled sample introduction system and combined with adequate wash times with 4% v/v aqua regia + 0.5% v/v HF between samples. The concentration of the remaining lithophile elements was determined with a conventional, cooled, Scott‐type spray chamber using a wash solution of 1% v/v HNO3. Total procedural blanks contributed between 0.01 to 0.5% to final sample concentrations and blank subtractions were typically unnecessary. Abundances for Li, Hf, Ba, Zr, Ga, Rb, Sr, La, Ce, Th and U were systematically higher, while those for the heavy rare earth elements (HREEs), Cu and Y were systematically lower in this study compared to USGS values for G‐2 and GSP‐2. This is likely to be related to, respectively, higher recoveries from more efficient digestion of refractory phases (i.e., zircon, tourmaline), and better resolution of interferences when using a HR‐ICP‐MS. Sample digestion experiments also showed that perchloric acid digestion in high pressure bombs resulted in superior recoveries and better precision for the bulk of the trace elements analysed. The concentration of the remaining elements overlapped within uncertainty with recommended reference values and with values determined in other studies using isotope‐dilution TIMS, ICP‐MS and XRF. Concentrations for the elements Cd, Sn, Sb, Ta, Bi, Tb, Ni and Mo are also reported for G‐2 and GSP‐2 reference materials. Our study shows therefore that it is feasible to determine thirty‐nine geologically relevant trace elements accurately and directly in granitoid sample digests when using a HR‐ICP‐MS, thereby negating the need for ion exchange or isotopic spiking.
Effect of a late evening snack on outpatients with liver cirrhosis
Authors: Aoyama Koji , Tsuchiya Masako , Mori Kenji , Kubo Yoshitsugu , Shiraishi Kei , Sakaguchi Eiki , Yamashita Satoyoshi , Sakaida Isao
Published: May 2007

Aims:  We have reported that one‐week administration of a late evening snack (LES) improved not only malnutrition but also glucose intolerance in hospitalized patients with liver cirrhosis. Thus, we investigated whether long‐term LES administration to outpatients for 3 months could reproduce the results obtained from hospitalized patients, especially improved glucose intolerance. If this treatment aggravated glucose intolerance, we tried to find any marker predicting this aggravation before the treatment.

Methods:  Outpatients were prescribed one pack of oral supplementation of a branched‐chain amino acid (BCAA)‐enriched nutrient, Aminoleban EN (210 kCal) as a LES without dietician supervision. Both before LES administration and after 3 months, glucose tolerance and liver function were examined using a 75 g oral glucose tolerance test (OGTT), biochemical parameters in blood and the relationship between glucose tolerance (area under the curve (AUC)) and the following serum markers.

Results:  Branched‐chain amino acid/tyrosine ratio (BTR), the number of red blood cells (RBC), and hematocrit (Ht) significantly increased, with significant reduction of blood NH3 level in patients with a blood glucose level less than 200 mg/dL 2 h after 75 g OGTT. However, the increase of AUC was seen after 3 months of LES administration in patients who had blood glucose higher than 200 mg/dL 2 h after 75 g OGTT. AUC weakly correlated positively with serum 7S collagen and negatively with choline esterase (ChE) and albumin (Alb).

Conclusion:  75 g OGTT is a useful marker to predict the worst outcome and avoid the adverse effect of LES treatment in liver cirrhosis patients if performed without adequate nutrient conduct by a dietician.
Protective effect of interferon‐α on the DNA‐ and RNA‐degrading pathway in anti‐Fas‐antibody induced apoptosis
Authors: Kocic Gordana , Bjelakovic Gordana , Pavlovic Dusica , Jevtovic Tatjana , Pavlovic Voja , Sokolovic Dusan , Basic Jelena , Cekic Snezana , Cvetkovic Tatjana , Kocic Radivoj , Stojanovic Svetlana
Published: May 2007

Aim:  Fas membrane‐associated polypeptide antigen is a receptor molecule responsible for apoptosis‐mediated signals. In animal models of acute viral hepatitis, apoptosis of hepatocytes is mediated by Fas‐death receptors; therefore, the aim of this study was to evaluate the effect of interferon (IFN)‐α on apoptotic markers and nuclease activity against different coding and non‐coding single and double stranded RNAs during Fas‐induced liver apoptosis.

Methods:  An in vivo experiment was performed with simultaneous administration of anti‐Fas (CD95) antibodies and IFN‐α, and an in vitro experiment was performed in hepatocyte cultures treated with anti‐Fas antibodies and IFN‐α.

Results:  Detection of apoptosis using Annexin V‐FITC/propidium iodide, Bcl‐2 and Bax expression in hepatocyte cultures confirmed the appearance of early apoptotic events and progression toward late apoptosis after anti‐Fas antibody treatment. IFN‐α had a tendency to retard the apoptosis process in Fas‐induced apoptosis by increasing the number of viable cells and decreasing the number of cells in late apoptosis, by increasing the percentage of Bcl‐2 positive cells, by decreasing the percentage of Bax positive cells, and by decreasing the nuclease activity compared to the anti‐Fas antibody treated group. Total DNA and RNA concentration was much reduced in the Fas group and DNA fragmentation assay provided evidence for increased DNA degradation. Enhanced nuclease activity against DNA, rRNA, poly(A), poly(C), poly(U), poly(I:C), and poly(A:U) was manifested in the anti‐Fas antibody treated group, except for the inhibitory‐bound alkaline RNase.

Conclusions:  The results demonstrate that the RNA‐degrading pathway in Fas‐induced apoptosis can accelerate the liberation of the latent enzyme from the inhibitor complex. IFN‐α prevented enormous, Fas‐ligand induced degradation of all the substrates used in this experimental study, most probably due to similarities in the signal transduction pathways. Investigations of death receptor‐induced apoptosis may lead to novel treatment combinations for patients with acute or chronic liver diseases.
Downregulated expression of metallothionein and its clinicopathological significance in hepatocellular carcinoma
Authors: Tao Xia , Zheng Jian‐Ming , Xu Ai‐Min , Chen Xin‐Fang , Zhang Shu‐Hui
Published: May 2007

Aim:  Metallothionein (MT) protein is related to different stages of development and progression of various tumors in humans. The aim of the present study was to investigate expression and localization of MT and their association with clinicopathological characteristics in hepatocellular carcinoma (HCC).

Methods:  Histological specimens of 400 HCC with corresponding non‐cancerous liver tissues were stained for MT (E9), P53 and Ki‐67 by immunohistochemical staining using tissue microarrays. RNA expression of MT‐1X and MT‐2A isoforms was determined by real‐time reverse transcription–polymerase chain reaction in a set of independent samples of 161 HCC.

Results:  Downregulated expression of MT at both mRNA and protein levels was detected in HCC, compared with non‐cancerous liver tissues. The frequencies of MT positivity were significantly lower in cases with positive hepatitis B surface antigen than in those with negative hepatitis B surfaceantigen (P = 0.042). The positive rate of MT expression was more frequent in tumors ≤2 cm than in tumors >2 cm in diameter (P = 0.007). There was a tendency for MT expression to decrease with the progression of histological grade. Mainly nuclear expression of MT correlated with poorly differentiated HCC. No statistical correlation was found between P53, Ki‐67 and MT expression.

Conclusions:  Downregulated expression of MT in HCC may play a role in hepatocarcinogenesis and be a marker of hepatocellular differentiation. Hepatitis B virus infection may be correlated to downregulated expression of MT. The mainly nuclear MT immunostaining may reflect an aggressive behavior in poorly differentiated HCC.
DEEP LEVEL DEFECTS IN SILICON CARBIDE
Authors: LEBEDEV A. A.
Published: May 2007

Results obtained in recent studies of deep centers in 6H-, 4H-, and 3C-SiC are analyzed. The ionization energies and capture cross sections of centers formed by doping of SiC with different types of impurities or by irradiation, as well as the corresponding parameters of intrinsic defects, are presented. The involvement of these centers in radiative and nonradiative recombination is examined. Analysis of published data shows that a strong influence is exerted by intrinsic defects in the SiC crystal lattice both on the formation of deep centers and on the properties of the epitaxial layers themselves, such as their doping level and polytype homogeneity.
SECOND-ORDER NONLINEAR OPTICAL PROPERTIES OF CHROMOPHORE-COATED PARTICLES: SYMMETRY CONSIDERATIONS
Authors: BAERT KASPER , WOSTYN KURT , VALLÉE RENAUD A. L. , CLAYS KOEN
Published: May 2007

The second-order nonlinear optical properties of polystyrene particles coated with two well-characterized nonlinear optical chromophores with different molecular symmetry have been studied. From the markedly different depolarization ratio for the hyper-Rayleigh scattering from the molecular scatterers and from the largely different second-harmonic intensity from particles coated with these chromophores, we conjecture that contributions from antisymmetric molecular electronic states are necessary to observe second-order nonlinear effects from centrosymmetrical particles in isotropic solution.
NONLINEAR OPTICS AND LIGHT LOCALIZATION IN PERIODIC PHOTONIC LATTICES
Authors: NESHEV DRAGOMIR N. , SUKHORUKOV ANDREY A. , KROLIKOWSKI WIESLAW , KIVSHAR YURI S.
Published: May 2007

We review the recent developments in the field of photonic lattices emphasizing their unique properties for controlling linear and nonlinear propagation of light. We draw some important links between optical lattices and photonic crystals pointing towards practical applications in optical communications and computing, beam shaping, and biosensing.
COUPLER-LOSS AND COUPLING-COEFFICIENT DEPENDENCE OF BISTABILITY AND INSTABILITY IN A FIBER RING RESONATOR: NONLINEAR BEHAVIORS
Authors: YUPAPIN P. P. , SAEUNG P. , SUWANCHAROEN W.
Published: May 2007

In this paper we demonstrate the dynamic simulation of light traveling in a nonlinear fiber optic ring resonator (FORR) with a single coupler. The mathematical relations describing the nonlinear characteristics of the FORR are derived from light transmission theory in linear optical systems. Optical nonlinear phenomena such as bifurcation and chaos are investigated for optical bistability and the Ikeda instability. It is found that for the Ikeda instability of light inside a FORR, the ring-cavity lifetime is much longer than the Kerr-effect response time of the fiber ring. Transmission curves of bistability and instability are shown as a function of the coupler insertion losses (γ) and the coupling coefficients (κ).
LOW-POWER ALL-OPTICAL SWITCHING USING A FIBER SAGNAC INTERFEROMETER WITH A PUMPED NONLINEAR COUPLER
Authors: LI CHUNFEI , XU GUANGMING , DOU NA , WANG FEI
Published: May 2007

We propose a novel Sagnac interferometer (SI) optical switch consisting of a pumped erbium-doped fiber 3dB coupler for a signal at 1.55 μm and a short fiber loop. The switching between the reflected and transmitted output powers can be accomplished by two approaches: using 980nm-pump power in the cross-pumping mode or using an additional signal power in the self-pumping mode. In the two modes, the switching powers are 40mW and 20mW, and the switching times are sub-nanoseconds and milliseconds, respectively. In the both cases, the switching powers are independent of the fiber-loop length, so that the power-length products for proposed SI switch can be smaller than that of other kind of nonlinear SI switches.
LOCAL WELL-POSEDNESS BELOW THE CHARGE NORM FOR THE DIRAC–KLEIN–GORDON SYSTEM IN TWO SPACE DIMENSIONS
Authors: D'ANCONA PIERO , FOSCHI DAMIANO , SELBERG SIGMUND
Published: May 2007

We prove that the Cauchy problem for the Dirac–Klein–Gordon equations in two space dimensions is locally well-posed in a range of Sobolev spaces of negative index for the Dirac spinor, and an associated range of spaces of positive index for the meson field. In particular, we can go below the charge norm, that is, the L2 norm of the spinor. We hope that this can have implications for the global existence problem, since the charge is conserved. Our result relies on the null structure of the system, and bilinear space-time estimates for the homogeneous wave equation.
THE SET OF CONCENTRATION FOR SOME HYPERBOLIC MODELS OF CHEMOTAXIS
Authors: DERBEL LOBNA , JABIN PIERRE EMMANUEL
Published: May 2007

Chemotaxis models are typically able to develop blow-up in finite times. For some specific models, we obtain some estimates on the set of concentration of cells (defined roughly as the points where the density of cells is infinite with a non-vanishing mass). More precisely we consider models without diffusion for which the cells' velocity decreases if the concentration of the chemical attractant becomes too large. We are able to give a lower bound on the Hausdorff dimension of the concentration set, one in the "best" situation where the velocity exactly vanishes for too large concentrations of attractant. This in particular implies that the solution may not form any Dirac mass.
Palmitate modulates intracellular signaling, induces endoplasmic reticulum stress, and causes apoptosis in mouse 3T3-L1 and rat primary preadipocytes
Authors: Guo Wen , Wong Siu , Xie Weisheng , Lei Tianluo , Luo Zhijun
Published: May 2007

Although fatty acids enhance preadipocyte differentiation in the presence of adequate hormone cocktails, little is known regarding their effects in the absence of these hormones. We have now shown that palmitate, a common long-chain saturated fatty acid, induced apoptosis in both mouse 3T3-L1 and rat primary preadipocytes grown in a normal serum-containing medium. Treatment of preadipocytes with palmitate induced multiple endoplasmic reticulum (ER) stress responses, evidenced by increased protein content of CHOP and GRP78 and splicing of XBP-1 mRNA, as well as altered phosphorylation of eIF2α and increased phosphorylation of JNK and Erk1/2. Intriguingly, palmitate induced an early activation of Akt but diminished both Akt activation and its protein mass after prolonged incubation (>6 h). In association with these changes, palmitate reduced expression of β-catenin and its downstream target, c-Myc and cyclin D1, two key prosurvival proteins. Overexpression of constitutively active Akt did not block the apoptotic effect of palmitate. Cotreatment with unsaturated fatty acids (oleate, linoleate) or with LiCl (a glycogen synthase kinase-3β inhibitor) attenuated the palmitate-induced apoptosis. Subsequent analysis suggested that the unsaturated fatty acids probably counteracted palmitate by reducing, not eliminating, ER stress, whereas LiCl probably improved viability by activating the Wnt signaling pathway. Cotreatment of palmitate with a standard adipogenic hormone cocktail also abolished the apoptotic effect and promoted adipocyte differentiation. Collectively, our results suggest that palmitate causes multiple cellular stresses that may lead to apoptosis in preadipocytes in the absence of adipogenic stimuli, highlighting the importance of exogenous hormones in directing cell fate in response to increased fatty acid influx.
Reversal by relaxin of altered ileal spontaneous contractions in dystrophic (mdx) mice through a nitric oxide-mediated mechanism
Authors: Baccari M. C. , Nistri S. , Vannucchi M. G. , Calamai F. , Bani D.
Published: May 2007

Altered nitric oxide (NO) production/release is involved in gastrointestinal motor disorders occurring in dystrophic (mdx) mice. Since the hormone relaxin (RLX) can upregulate NO biosynthesis, its effects on spontaneous motility and NO synthase (NOS) expression in the ileum of dystrophic (mdx) mice were investigated. Mechanical responses of ileal preparations were recorded in vitro via force-displacement transducers. Evaluation of the expression of NOS isoforms was performed by immunohistochemistry and Western blot. Normal and mdx mice were distributed into three groups: untreated, RLX pretreated, and vehicle pretreated. Ileal preparations from the untreated animals showed spontaneous muscular contractions whose amplitude was significantly higher in mdx than in normal mice. Addition of RLX, alone or together with l-arginine, to the bath medium depressed the amplitude of the contractions in the mdx mice, thus reestablishing a motility pattern typical of the normal mice. The NOS inhibitor NG-nitro-l-arginine (l-NNA) or the guanylate cyclase inhibitor ODQ reversed the effects of RLX. In RLX-pretreated mdx mice, the amplitude of spontaneous motility was reduced, thus resembling that of the normal mice, and NOS II expression in the muscle coat was increased in respect to the vehicle-pretreated mdx animals. These results indicate that RLX can reverse the altered ileal motility of mdx mice to a normal pattern, likely by upregulating NOS II expression and NO biosynthesis in the ileal smooth muscle.
Kinematics of the Rotational Vestibuloocular Reflex: Role of the Cerebellum
Authors: Walker Mark F. , Tian Jing , Zee David S.
Published: May 2007

We studied the effect of cerebellar lesions on the 3-D control of the rotational vestibuloocular reflex (RVOR) to abrupt yaw-axis head rotation. Using search coils, three-dimensional (3-D) eye movements were recorded from nine patients with cerebellar disease and seven normal subjects during brief chair rotations (200°/s2 to 40°/s) and manual head impulses. We determined the amount of eye-position dependent torsion during yaw-axis rotation by calculating the torsional-horizontal eye-velocity axis for each of three vertical eye positions (0°, ±15°) and performing a linear regression to determine the relationship of the 3-D velocity axis to vertical eye position. The slope of this regression is the tilt angle slope. Overall, cerebellar patients showed a clear increase in the tilt angle slope for both chair rotations and head impulses. For chair rotations, the effect was not seen at the onset of head rotation when both patients and normal subjects had nearly head-fixed responses (no eye-position-dependent torsion). Over time, however, both groups showed an increasing tilt-angle slope but to a much greater degree in cerebellar patients. Two important conclusions emerge from these findings: the axis of eye rotation at the onset of head rotation is set to a value close to head-fixed (i.e., optimal for gaze stabilization during head rotation), independent of the cerebellum and once the head rotation is in progress, the cerebellum plays a crucial role in keeping the axis of eye rotation about halfway between head-fixed and that required for Listing's Law to be obeyed.
Altered Corticostriatal Neurotransmission and Modulation in Dopamine Transporter Knock-Down Mice
Authors: Wu Nanping , Cepeda Carlos , Zhuang Xiaoxi , Levine Michael S.
Published: May 2007

Dopamine (DA) modulates glutamate neurotransmission in the striatum. Abnormal DA modulation has been implicated in neurological and psychiatric disorders. The development of DA transporter knock-down (DAT-KD) mice has permitted modeling of these disorders and has shed new light on DA modulation. DAT-KD mice exhibit increased extracellular DA, hyperactivity, and alterations in habituation. We used whole cell patch-clamp recordings from visually identified striatal neurons in slices to examine the effects of DAT-KD on corticostriatal transmission. Electrophysiological recordings from medium-sized spiny neurons in the dorsal striatum revealed alterations in both amplitude and frequency, of spontaneous glutamate receptor-mediated synaptic currents in cells from DAT-KD mice. Furthermore, kinetic analyses revealed that these currents had shorter half-amplitude durations and faster decay times. In contrast, GABA-receptor–mediated synaptic currents were not altered. Striatal neurons from DAT-KD mice also responded differently to amphetamine, cocaine, and DA D2-receptor agonists or antagonists compared with wildtype (WT) littermate controls. In WTs amphetamine and cocaine reduced the frequency of spontaneous glutamate currents and these effects appeared to be mediated by activation of D2 receptors. In contrast, in DAT-KD mice either no changes or only small increases in frequency occurred. D2-receptor agonists or antagonists also had opposing effects in WT and DAT-KD mice. Together, these results indicate that chronically increased extracellular DA produces long-lasting changes in corticostriatal communication that may be mediated by changes in D2-receptor function. These findings have implications for understanding mechanisms underlying attention deficit hyperactivity disorder and Tourette's syndrome and may provide insights into novel therapeutic approaches.
Disruption of insulin-like growth factor-I expression in type IIαI collagen-expressing cells reduces bone length and width in mice
Authors: Govoni Kristen E. , Lee Seong Keun , Chung Yoon-Sok , Behringer Richard R. , Wergedal Jon E. , Baylink David J. , Mohan Subburaman
Published: May 2007

It is well established that insulin-like growth factor (IGF)-I is critical for the regulation of peak bone mineral density (BMD) and bone width. However, the role of systemic vs. local IGF-I is not well understood. To determine the role local IGF-I plays in regulating BMD and bone width, we crossed IGF-I flox/flox mice with procollagen, typeIIαI-Cre mice to generate conditional mutants in which chondrocyte-derived IGF-I was disrupted. Bone parameters were measured by dual X-ray absorptiometry at 2, 4, 8, and 12 wk of age and peripheral quantitative computed tomography at 12 wk of age. Body length, areal BMD, and bone mineral content (BMC) were reduced ( P < 0.05) between 4 and 12 wk in the conditional mutant mice. Bone width was reduced 7% in the vertebrae and femur ( P < 0.05) of conditional mutant mice at 12 wk. Gains in body length and total body BMC and BMD were reduced by 27, 22, and 18%, respectively ( P < 0.05) in conditional mutant mice between 2 and 4 wk of age. Expression of parathyroid hormone related protein, parathyroid hormone receptor, distal-less homeobox (Dlx)-5, SRY-box containing gene-9, and IGF binding protein (IGFBP)-5 were reduced 27, 36, 45, 33, and 45%, respectively, in the conditional mutant cartilage ( P < 0.05); however, no changes in Indian hedgehog, Dlx-3, growth hormone receptor, IGF-I receptor, and IGFBP-3 expression were observed ( P ≥ 0.20). In conclusion, IGF-I from cells expressing procollagen type IIαI regulates bone accretion that occurs during postnatal growth period.
Model-Generated Predictions of Dry Thunderstorm Potential
Authors: Rorig Miriam L. , McKay Steven J. , Ferguson Sue A. , Werth Paul
Published: May 2007

Dry thunderstorms (those that occur without significant rainfall at the ground) are common in the interior western United States. Moisture drawn into the area from the Gulfs of Mexico and California is sufficient to form high-based thunderstorms. Rain often evaporates before reaching the ground, and cloud-to-ground lightning generated by these storms strikes dry fuels. Fire weather forecasters at the National Weather Service and the National Interagency Coordination Center try to anticipate days with widespread dry thunderstorms because they result in multiple fire ignitions, often in remote areas. The probability of the occurrence of dry thunderstorms that produce fire-igniting lightning strikes was found to be greater on days with high instability and a deficit of moisture at low levels of the atmosphere. Based on these upper-air variables, an algorithm was developed to estimate the potential of dry lightning (lightning that strikes the ground with little or no rainfall at the surface) when convective storms are expected. In the current study, this algorithm has been applied throughout the western United States, with modeled meteorological variables rather than the observed soundings that have previously been used, to develop a predictive scheme for estimating the risk of dry thunderstorms. Predictions of the risk of dry thunderstorms were generated from real-time forecasts using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5) for the summers of 2004 and 2005. During that period, 240 large lightning-caused fires were ignited in the model domain. Of those fires, 40% occurred where the probability of dry lightning was predicted to be equal to or greater than 90% and 58% occurred where the probability was 75% or greater.
Possible Misidentification of Rain Type by TRMM PR over Tibetan Plateau
Authors: Fu Yunfei , Liu Guosheng
Published: May 2007

Rain-type statistics derived from Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) standard product show that some 70% of raining pixels in the central Tibetan Plateau summer are stratiform—a clear contradiction to the common knowledge that rain events during summer in this region are mostly convective, as a result of the strong atmospheric convective instability resulting from surface heating. In examining the vertical distribution of the stratiform rain-rate profiles, it is suspected that the TRMM PR algorithm misidentifies weak convective rain events as stratiform rain events. The possible cause for this misidentification is believed to be that the freezing level is close to the surface over the plateau, so that the ground echo may be mistakenly identified as the melting level in the PR rain classification algorithm.
Role of Novel Biomarkers of Inflammation in Patients With Stable Coronary Heart Disease
Authors: Oren Hüseyin , Erbay Ali R. , Balci Mustafa , Çehreli Sengül
Published: May 2007

Atherosclerosis is a dynamic chronic inflammatory process, and some inflammatory biomarkers have roles in this process. The levels of C-reactive protein (CRP) in patients with chronic stable coronary heart disease (CHD) have not been investigated well, and the levels of macrophage colony-stimulating factor (M-CSF) and interleukin-3 (IL-3) in patients with chronic stable CHD and the effects of these cytokines on atherogenesis are not known. To determine whether new inflammatory biomarkers have roles in atherosclerosis, the authors measured the levels of CRP, M-CSF, and IL-3 in patients with chronic stable CHD and in healthy controls. They measured plasma CRP concentrations by using a highly sensitive CRP reagent with immunonephelometric method, and plasma M-CSF and IL-3 concentrations with the help of a commercial enzyme-linked immunoassay test in 31 patients with chronic stable CHD documented by coronary angiography and in 22 age-matched healthy control subjects documented by coronary angiography. Mean plasma CRP, M-CSF, and IL-3 concentrations in patients with chronic stable CHD were significantly higher than those in controls (8.2 vs 4.6 mg/L, 195.3 vs 28.9 pg/mL, 173 vs 118 ng/mL, respectively, pπ.05). CRP, M-CSF, and IL-3 were all increased in patients with chronic stable CHD relative to controls. These findings suggest that these are new inflammatory biomarkers that may have important roles in the development of atherosclerotic lesions.
Coronary Artery Spasm-Related Acute Coronary Syndrome in Patients With Coexisting Spasm of Angiographically Normal Coronary Artery and Fixed Narrowing of the Remaining Vessels
Authors: Yang Ning-I , Hung Ming-Jui , Cherng Wen-Jin
Published: May 2007

Fourteen patients with acute coronary syndrome are presented in this study. During angiography, hemodynamically significant coronary artery disease was demonstrated; however, it was not consistent with the electrocardiographic findings. The coronary artery spasm could be provoked in the rest of the angiographically normal coronary artery. Patient chest pain disappeared after administration of calcium channel blockers and/or isosorbide dinitrite. It is suggested that (1) both coronary artery spasm with no fixed stenosis and coronary atherosclerosis with fixed coronary stenosis can coexist in the same patient and cause symptoms, and (2) it is important to identify the predominant cause of symptoms, which then guides correct management.
Defective Adrenergic Responses in Patients With Arsenic-induced Peripheral Vascular Disease
Authors: Lee Chih-Hung , Chang Huoy-Rou , Chen Jau-Shiuh , Chen Gwo-Shing , Yu Hsin-Su
Published: May 2007

Blackfoot disease is an endemic arsenic-induced peripheral vascular disease in southern Taiwan. The main pathologic feature is atherosclerosis, which may relate to imbalances of the adrenergic system. The purpose of this study is to investigate the peripheral adrenergic responses of patients with blackfoot disease. Eight patients with blackfoot disease and four age-matched healthy controls were enrolled in this study. Baseline cutaneous perfusion was measured with a laser Doppler flowmeter. The response of alpha-adrenoceptors in the cutaneous microcirculation was assessed with laser Doppler flowmetry with iontophoresis of phenylephrine into the nailfold. In vitro binding with 125I-cyanopindolol determined beta-adrenoceptor density in lymphocytes. The cyclic adenosine monophosphate (cAMP) level at baseline and after isoproterenol stimulation reflects lymphocyte beta-adrenergic responsiveness. Results revealed persistently decreased skin perfusion in patients with blackfoot disease. In contrast, there was a transient decrease in skin perfusion in healthy controls after iontophoresis of phenylephrine. Both beta-2 receptor density and isoproterenol-stimulated cAMP levels in lymphocytes decreased. Increased peripheral alpha-adrenergic response and decreased beta-2—adrenergic response are related to increased vascular tone and result in atherosclerosis. Our findings of accentuated alpha-adrenergic response in microcirculation and decreased lymphocyte beta-2—adrenoceptor response play an important role in the pathogenesis of atherosclerosis in blackfoot disease.