bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship Between Coating Defects and the Limiting Flux Density a Cooled Laser Mirror Can Withstand
Authors: Palmer JR , Bennett HE
Published: March 2009

The flux density which a cooled laser mirror can handle without catastrophic damage is predicted to be limited in typical situations by absorbing defects on the optical surface rather than by mirror reflectance. In this case, failure is predicted to occur either through coating damage in the vicinity of the defect or by burnthrough of the cooled faceplate following vapor barrier formation at the coolant-faceplate interface. Expressions are developed which predict the limiting defect size for a given flux density as a function of (1) thickness and composition of the faceplate, (2) transport properties and fluid mechanics of the liquid coolant, and (3) conditions generating a hydrodynamic crisis at the liquid coolant stagnation boundary beneath the defect. This parametric analysis can be used to optimize faceplate thickness as a function of mirror material, coolant flow, coating damage threshold, heat exchanger design, and the expected maximum size and absorption of multilayer film coating defects. According to this analysis, for thin faceplates the optimum faceplate thickness may be determined by the coating process rather than by average heat transfer considerations.
Comment on “Intense-field Effects in Solids”
Authors: Vaidyanathan A , Guenther AH
Published: March 2009

Recent theoretical work by Jones and Reiss predict that the effective energy gap of a crystalline solid in the presence of electromagnetic radiation increases with radiation intensity. Thus, at sufficiently great intensities higher order multiphoton processes could become more probable than lower order processes. It is shown that, although this behavior contradicts the well-known perturbative results in the low intensity region, it appears to be confirmed by the experimental data on GaP at 0.694 μm, due to Pyshkin et al. Theoretical and experimental results regarding the intensities needed for the observation of this phenomenon are compared, and its implications for nonlinear optics are discussed.
Nonlinear Refractive Coefficient and Self-Focusing Damage in Glasses
Authors: He D , Fuxi G
Published: March 2009

We have investigated some nonlinear optical effects in a series of optical glasses and laser glasses. Using different methods, we have measured the nonlinear refractive coefficient of these glasses. We have analyzed the possible mechanisms resulting in refractive index change in glass and calculated their nonlinear refractive coefficients. We have also discussed the dependence of laser-induced damage and thermo-optical blooming on nonlinear refractive coefficients.
The Jext-Integral Based on the Concept of Effective Energy Release Rate
Authors: Miyamoto H , Kageyama K , Kikuchi M , Machida K
Published: March 2009

The Jext-integral is introduced as the measure of the effective energy release rate in the process zone, and the expression of the two- and three-dimensional Jext-integrals are obtained. The Jext-integral is the measure of the inhomogeneities caused by the large deformation at the crack tip. The path-independent expression of the Jext-integral is also introduced, which is useful when there are the body force and the eigen stress fields. For the two-dimensional case, some properties of the Jext-integral are discussed and the relation to GΔ is shown. It is pointed out that by considering a finite region like the process zone, Jext can overcome the shortages of the energy concept as the fracture criterion. The Jext-integral is evaluated for some basic problems.
A Criterion Based on Crack-Tip Energy Dissipation in Plane-Strain Crack Growth Under Large-Scale Yielding
Authors: Saka M , Shoji T , Takahashi H , Abé H
Published: March 2009

In order to assess the proper resistance of elastic-plastic materials for stable crack growth in Mode I under plane-strain conditions with large-scale yielding, a fracture criterion based on a rate of the crack-tip energy dissipation with crack extension was proposed. The criterion can be expressed as TW = (TW)c, where TW is a newly developed tearing parameter defined as TW = (1/R)(E/σ02)(dp/da). The parameter TW is a dimensionless representation of the increment of plastic work done, dp/da, in a circular region of characteristic radius R at the growing crack tip, and TW is related directly as the amplitude to the singularity field at a growing crack tip.

A procedure of experimental determination of (TW)c was described, where the crack-tip energy dissipation, Wp, was evaluated by means of the recrystallization-etch technique, and the width of recrystallized region observed parallel to the growing crack surface was used as the characteristic radius R. With special reference to a nonlinearity of the J-resistance curve for a wide range of crack extension, a conventional estimation procedure of the rate of crack-tip energy dissipation in terms of γ[=(½)β2σ02R(TW)c] was also described.

Furthermore, the TW criterion was verified experimentally and numerically in comparison with other candidate tearing parameters TJ[=(E/σ02)(dJ/da)] and Tδ[=(E/σ0) (dδ/da)]. A significant superiority of TW over TJ and Tδ [crack-opening angle (COA)] was emphasized as a characterizing parameter for crack growth. It was shown that the critical value of TW during crack growth was not affected by specimen size, side groove depth, and an amount of crack extension.
Bounds for Fully Plastic Crack Problems for Infinite Bodies
Authors: He MY , Hutchinson JW
Published: March 2009

For cracks in infinite bodies it is shown that modified principles of complementary potential energy and potential energy can be used to generate upper and lower bounds to the J-integral of the deformation theory of plasticity. These principles are used to obtain relatively tight numerical bounds on J for two basic plane strain problems: the finite crack in an infinite plane and the edge-crack in a semi-infinite plane. In both problems the material is incompressible with a pure power relation between stress and strain. Upper bounds for the plane stress problems are also given.
Penny-Shaped Crack in a Round Bar of Power-Law Hardening Material
Authors: He MY , Hutchinson JW
Published: March 2009

A study is made of the deformation of a round bar of pure power-law hardening material under tension containing a central penny-shaped crack. Several important issues related to fracture mechanics are examined, including the near-tip stress and strain field and its relation to the analogous problem in plane strain.
A Superposition Method for Nonlinear Crack Problems
Authors: Yagawa G , Aizawa T
Published: March 2009

The finite-element evaluation of nonlinear cracks in power-hardening materials involves some numerical difficulties: the incompressibility in the plane-strain condition and the representation of the nonlinear crack singularity. In the present paper, the eigenmodes of Hutchinson-Rice-Rosengren (HRR) singularity at the nonlinear crack tip are obtained numerically by the finite-element eigenfunction calculation. Superposing the singularity functions thus obtained on the finite-element displacement, the J-integral values for various structures are determined directly from a coefficient of the superposed function. As for the numerical examples, we take the center-cracked plate, the double-edge-cracked plate, and the single-edge-cracked plate. Several comparison studies are made between the present and the other relevant results.
Evaluation of J-Integral for Surface Cracks
Authors: Shiratori M , Miyoshi T
Published: March 2009

A new finite-element program has been developed in order to analyze the stress-intensity factor K and J-integral for surface cracked plates and shells. The program is composed of the flat shell elements and the line spring elements which are based upon the line spring model proposed by Rice. Summary of results analyzed by this program is as follows:

1. In the analysis of K for surface-cracked rectangular plates, the results have been in good agreement with the three-dimensional finite-element results obtained by Raju and Newman. The computing time is one order less than the three-dimensional finite-element analysis. 2. Nearly the same results as those by Parks have been obtained in the analysis of the J-integral for surface-cracked rectangular plates. 3. As a practical application of this program, K and J have been analyzed for surface-cracked part-circular cylindrical shells. The effect of curvature has been found to lower the values of K and J slightly. Therefore, estimates of K and J by those of flat plates for the equivalent crack configuration give conservative results.
Effects of Thickness on J-Integral in Structures
Authors: Sakata M , Aoki S , Kishimoto K , Kanzawa M , Ogure N
Published: March 2009

The distribution of the Ĵ-integral, an extension of the J-integral, is calculated along the crack front of compact specimens of varying thicknesses by a three-dimensional elastic-plastic finite-element method. The Ĵ-integral takes the maximum value at the midthickness and smaller values near the plate surfaces, and the Ĵ-value at the midthickness coincides with the J-value determined from the computed load versus load-line displacement curve by using the Merkle-Corten formula. These results explain why the plane-strain fracture toughness value JIc can be experimentally determined by using specimens of moderate thickness.

To avoid the expense of three-dimensional computations, an empirical formula based on a two-dimensional finite-element method is proposed to determine the J-value which coincides with the Ĵ-value at midthickness in a cracked structure. Experimental results on compact specimens of 304 and 4340 steels and also on rotating disks of 4340 steel indicate that the onset of crack growth in a structure with finite thickness can be estimated by using the empirical formula and the JIc-value of the compact specimen.
Stable Crack Extension Rates in Ductile Materials: Characterization by a Local Stress-Intensity Factor
Authors: Hart EW
Published: March 2009

A theory is presented for the steady-state propagation of a Mode III crack in a ductile material. The inelastic deformation of the matrix material and the cracking mechanism are both described by real-time rate constitutive laws. The theory leads to realistic nonsingular stresses and relates the crack-tip velocity v to the apparent stress-intensity factor KA that characterizes the remote loading. It is shown that the crack-tip behavior is characterized by a local stress-intensity factor K and that the inelastic deformation is described by a plastic stress-intensity factor KP such that K = KA + KP. These stress-intensity factors are all well defined even though the stress is nonsingular.
Field and Data Compilation Methods Used in the Inventory of the Peatlands of New Brunswick, Canada
Authors: D Keys , Henderson RE
Published: March 2009

The New Brunswick Department of Natural Resources has completed a detailed assessment of the peatlands of the Province. All peatlands exceeding 25 hectares have been investigated, except those within the boundaries of National Parks and military bases.

An airphoto study was followed by the field investigation of 21 000 sites between 1975 and 1981. The methods used are similar to those of the Geological Survey of Finland. Investigation sites were established at 100-m intervals along grid lines. The elevation of each site was determined. A sample core was recovered at each site using a Hiller auger. The botanical constituents and the decomposition (according to the von Post scale) of each interval were determined. Surface vegetation, bottom sediment, and other factors were also recorded at each site. One or two representative sites were selected on most major peatlands for determination of several physical and chemical characteristics. The peat type and decomposition of each sample were recorded to enable grouping of results. The determinations made are dependent on the utilization potential of the site.

Calculations were performed with the aid of a computer. Information can be retrieved at the site, bog, and regional levels. Over 600 variables can be used as grouping parameters at the regional level. Contoured peat isopach and elevation maps are produced for each peatland. Cross sections (profiles) displaying peat type and decomposition are drawn for each grid line. The inventory supplies multi-use information which enables assessment of utilization options by various disciplines and provides the basis for development of a long-term resource management plan.
Relationships Between Dry Density, Moisture Content, and Decomposition of Some New Brunswick Peats
Authors: Klemetti V , Keys D
Published: March 2009

The New Brunswick Department of Natural Resources has carried out a detailed inventory of the peatlands in the Province. The compiled information includes estimates of the in situ volumes of peat in each deposit. When a peat mining development is being considered, it is often desirable to convert these “measured resource” estimates to tonnes of fuel peat or standard bales of horticultural peat. The quantity of dry solids for a given in situ volume (that is, dry density) should be known for reliable conversions to be made. In the present study the relationships between dry density, moisture content, and degree of humification (decomposition) have been investigated to determine the reliability of predicting dry density on the basis of these variables.

Representative sites for sample collection were selected using the inventory information. At each site a sample core was recovered for the entire thickness of the deposit and subdivided into intervals according to changes in botanical composition and degree of humification (von Post scale).

The results obtained were grouped according to dominating peat type and degree of humification. The relationships for both moisture content versus humification and dry density versus humification had relatively weak correlations. A strong correlation between dry density and moisture content was observed, the degree of humification having little influence on the relationship.
A Finite-Element Study of the Asymptotic Near-Tip Fields for Mode I Plane-Strain Cracks Growing Stably in Elastic-Ideally Plastic Solids
Authors: Sham T-L
Published: March 2009

The asymptotic near-tip stress and deformation fields for a Mode I plane-strain crack growing quasi-statically in an elastic-ideally plastic solid under small-scale yielding conditions are analyzed numerically by the finite-element method. The asymptotic analyses of Rice and Sorensen; Rice, Drugan, and Sham; and Drugan, Rice, and Sham predict that the crack opening rate ˙δ at a small distance r from the growing crack tip under contained yielding conditions is given by ˙δ=˙Jσ0+βσ0E˙aℓnRrasr→0 where a is the crack length, σ0 the tensile yield strength, E Young's modulus, J the farfield value of the J-integral evaluated on contours in the elastic region, β = 5.462 (Drugan et al) for Poisson ratio ν = 0.3, and the parameters α and R are undetermined by the asymptotic analysis. The finite-element solutions generated are very detailed, with the maximum extent of the plastic zone being about 100 times the smallest element size. This high resolution in the finite-element solution enables correlation of the finite-element results with the asymptotic crack opening rate to be made and the expressions for the parameters α and R to be determined. Various crack growth histories are simulated by relaxing the nodal force at the crack tip and simultaneously increasing the external applied load in order to investigate the possible dependence of α and R on the crack growth history. The maximum amount of crack growth simulated is about 20 percent of the maximum extent of the plastic zone size. The numerical results reveal that a well-defined elastic unloading sector develops and moves with the advancing crack tip and its location coincides well that predicted by the asymptotic analysis. Estimation from the numerical results gives β = 5.46, which is in very good agreement with the asymptotic result. The parameter α is found to be independent of the crack growth histories examined and has a value of 0.58. An attempt to relate R to the quantity EJ/σ02 is made. However, it is found that the parameter s, defined by s ≡ R/(EJ/σ02), varies in a range 0.113 to 0.133 for the crack growth histories simulated. Thus, the precise definition for R remains unclear.
The Macrophage in Fibrogenesis by Quartz
Authors: Heppleston AG
Published: March 2009

The in vitro interaction of macrophages with ingested quartz led to the formation of a factor which when applied to fibroblasts stimulated their production of hydroxyproline without evidence of proliferation, an effect which titanium dioxide failed to induce. Inhaled quartz, however, also led to a pronounced degree of alveolar lipo-proteinosis, the lipid component of which, when introduced parenterally into other animals, stimulated proliferation of the monocytic line of marrow cells, from which macrophages are derived and populate the lung. The interrelation and implications of these two aspects of the macrophage response to silica are outlined.
Influence of Environment and Specimen Thickness on Fatigue Crack Growth Data Correlation by Means of Elber-Type Equations
Authors: Ewalds HL , van Doorn FC , Sloof WG
Published: March 2009

The effects of environment and specimen thickness on crack closure in 2024 aluminum alloy were investigated by using constant-amplitude fatigue tests. Crack growth rates for all test conditions were correlated with ΔKeff values derived from equations based on the crack closure theory of Elber. Crack closure behavior was confirmed to be independent of environment, except for a small deviation ascribed to corrosion product wedging. Surprisingly, the Elber-type equations worked equally well for all specimen thicknesses; a possible explanation is offered. These results have important implications with respect to fatigue crack growth prediction models based on crack closure effects.
Corrosion-Fatigue Crack Growth Characteristics of Several HY-100 Steel Weldments with Cathodic Protection
Authors: Davis DA , Czyryca EJ
Published: March 2009

The corrosion-fatigue crack growth properties of several types of HY-100 steel weldments were studied, primarily in an environment of seawater with cathodic protection by zinc anode. Shielded metal-arc (SMAW), gas metal-arc (GMAW) of both pulsed and spray are processes, and submerged-arc (SAW) weldments were included. The fatigue crack growth tests were conducted on compact specimens removed from the weldments to confine the path of the growing crack in all-weld metal. Constant-amplitude sinusoidal loads were applied at a frequency of 0.17 Hz with a load ratio (minimum-to-maximum) of 0.10.

In general, fatigue crack growth in weldments was considerably slower than that in HY-100 plate under the same conditions of load and environment, where the applied potential accelerated crack growth rate. The results showed minor differences among the weldments. It was suggested that the residual stress state along the weld centerline, the inhomogeneity of the weld metal with respect to the crack path, defects, and minor porosity all act to retard crack growth, especially at lower stress intensity levels. These factors tend to mask the environmental effects. However, weldments prepared with high heat input showed greater resistance to fatigue crack propagation than weldments prepared at low heat input. The corrosion fatigue crack growth exhibited by the HY-100 weldments was similar to that of HY-80 and HY-130 weldments where weld process, environment, and loading conditions were similar.
Effect of Microstructure and Strength of Low-Alloy Steels on Cyclic Crack Growth in High-Temperature Water
Authors: Shoji T , Nakajima H , Tsuji H , Takahashi H , Kondo T
Published: March 2009

The microstructural variability existing in weld heat-affected zones (HAZ) of SA533 Grade B steel has a strong influence on the fatigue crack growth rate of the material in a simulated nuclear reactor environment. In particular, considerably high susceptibility to environmentally enhanced cracking has been noted in the coarse grains of tempered martensite. This phenomenon is considered to be important not only in connection with predicting the cracking of the weld HAZ structures but also in elucidating the mechanism of crack growth enhancement in the high-temperature water environment. The materials used in the study are primarily SA533 Grade B and several other low-alloy steels including SA387, SA542, SA543, JIS SPV 46Q, and AISI 4340. Different heat treatments were given to these alloys to obtain a variety of microstructures and strengths. The results obtained show a general tendency for the crack growth rates of higher-strength materials to be more substantially accelerated in the simulated boiling-water reactor (BWR) water environment as the stress ratio is shifted from 0.1 to 0.5. In order to explore the operation of the cracking mechanism under dynamic loading, slow strain rate tests (SSRTs) were also performed. As with the cyclic crack growth rate tests, the materials with higher yield strengths exhibited highly enhanced crack growth rates and showed Ji values much reduced compared with those obtained in 288°C air. Furthermore, the crack growth rates under cyclic loading are directly compared with those obtained by the SSRT technique in terms of time-based crack growth rate in the water environment and in air by using plots of (da/dt)E versus (da/dt)air where (da/dt)E is the time-based crack growth rate in an aggressive environment and (da/dt)air is the rate in air. A satisfactory correspondence can be obtained between corrosion-fatigue test crack growth rates and those obtained by SSRTs.
Corrosion Fatigue of Welded Steel Joints under Narrow-Band Random Loading
Authors: Booth GS
Published: March 2009

The object of the work was to provide useful information regarding the fatigue behavior of offshore platforms. Fatigue tests were carried out on welded steel joints under environmental conditions representative of the North Sea. These tests were carried out under narrow-band random loading in an attempt to simulate the variable-amplitude loading experienced by a platform.

The joints were tested in seawater under freely corroding, intermittently immersed, and cathodically protected conditions. Two mean stress levels were studied. The results were assessed using linear cumulative damage procedures based on both the design S-N curve and experimental constant-amplitude data.
Influence of Weld Profile on Fatigue of Welded Structural Steel in Seawater
Authors: Nerolich SM , Martin PE , Hartt WH
Published: March 2009

Welded connections are generally recognized as being fatigue critical in the case of engineering systems such as offshore structures. As part of a research program aimed at better understanding how such connections respond to cyclic stresses, ABS DH32 steel plate specimens were fatigued under conditions that approached those experienced by offshore structures. The component of this study reported herein addresses quantification of the weld geometry for selected specimens employed in the program. Additionally, a finite-element analysis was developed from which the elastic stress concentration factor for the weld toe region was projected. The case of undercutting, which was apparent on one specimen that failed prematurely, was also analyzed. Results of this analysis have been evaluated in terms of notch member fatigue theory, and conclusions have been reached regarding those geometrical parameters of welds and undercuts which are most influential with regard to fatigue and corrosion fatigue.
Fatigue Crack Growth Measurement and Data Analysis
Authors: Hudak SJ , Bucci RJ
Published: March 2009

Description

A comprehensive, authoritative assessment of new developments in fatigue crack growth testing and of problems in the use of fatigue cracks growth rate information in materials’ evaluation, design, and reliability assessment.
Statistical Analysis of Fatigue Data
Authors: Little RE , Ekvall JC
Published: March 2009

Description

The 7 papers contained in this book cover two major areas:

• maximum likelihood analysis as a tool in the statistical analysis of fatigue data and in the study of alternative models

• assessment of fatigue variability using statistically planned test programs with appropriate replication.
Distillate Fuel Stability and Cleanliness
Authors: Stavinoha LL , Henry CP
Published: March 2009

Description

This book contains papers which cover current and future needs for tests to predict and monitor the stability and cleanliness, requirements for various applications; anticipated trends, future fuels, fuel distribution problems, microbiological contamination, test methods for stability and cleanliness, and refinery processes which improve stability.
Avian and Mammalian Wildlife Toxicology: Second Conference
Authors: Kenaga EE , Lamb DW
Published: March 2009

Description

This publication addresses the important wildlife toxicology problems such as: selection of surrogate species; predicting toxicity; matching concentrations of chemicals in various media with concentration in organisms, which cause various toxicological effects or responses.
Fracture Mechanics: Fourteenth Symposium—Volume I: Theory and Analysis
Authors: Lewis JC , Sines G
Published: March 2009

Description

The Fourteenth National Symposium on Fracture Mechanics was held in Los Angeles, Calif., 30 June-2 July 1981. ASTM Committee E24 on Fracture Testing sponsored the symposium. J. C. Lewis, of the TRW Space and Technology Group, and George Sines, of the University of California at Los Angeles, served as symposium chairmen and edited this publication.
Frictional Interaction of Tire and Pavement
Authors: Meyer WE , Walter JD
Published: March 2009

Description

This publication focuses on some of the current technical challenges confronting researchers working in this field. 16 papers comprise this book's contents and look into a number of problems that are inherent in tire and pavement surfaces and their interaction under a broad range of conditions.
Probabilistic Fracture Mechanics and Fatigue Methods: Applications for Structural Design and Maintenance
Authors: Bloom JM , Ekvall JC
Published: March 2009

Description

STP 798 represents the state of the art application of probabilistic aspects of fracture mechanics and fatigue. The papers comprising this publication's contents have been divided into two general categories: probabilistic fracture mechanics and statistical aspects of fatigue.
Properties of Flexible Pavement Materials
Authors: Emery JJ
Published: March 2009

Description

Of great value to the paving engineer, this publication covers a wide range of flexible pavement materials, and their laboratory and field characterization. The themes of the book include: laboratory characterization of soils, aggregates, binders, and additives; characterization of mixes incorporating sulfur and sulfur binders; properties of asphalt mixes; and field characterization of flexible pavements.
Behavior of Polymeric Materials in Fire
Authors: Schaffer EL
Published: March 2009

Description

This publication focuses on the behavior of polymeric materials in high energy of fire environments. The polymeric materials included are both naturally occurring-such as wood and wool-and in many synthetic forms-polyolefins, polyethylene terephthalate, polyvinyl chloride, neoprene, polyethylene and others.
Testing of Peats and Organic Soils
Authors: Jarrett PM
Published: March 2009

Description

The Symposium on Testing of Peats and Organic Soils was held on 23 June 1982 in Toronto, Canada. ASTM Committee D18 on Soil and Rock sponsored the event. The Peatlands Subcommittee of the Associate Committee on Geotechnical Research of the National Research Council of Canada was co-sponsor.
Vitamin D in relation to metabolic risk factors, insulin sensitivity and adiponectin in a young Middle-Eastern population
Authors: Gannagé-Yared Marie-Hélène , Chedid Rima , Khalife Simon , Azzi Emmanuel , Zoghbi Fernand , Halaby Georges
Published: March 2009

Objectives

Several studies suggest a link between circulating 25-hydroxyvitamin D (25(OH)D) and metabolic risk factors. However, this relation has been mainly studied in elderly and/or obese subjects. In addition, the relation between 25(OH)D and adiponectin is unclear. The purpose of this study is to look at these relations in non-obese young individuals.

Design

We investigated the relation between serum 25(OH)D and adiposity, blood pressure, glucose metabolism, lipid profile, and adiponectin in 381 randomly selected university students (201 males and 180 females, mean age 23.9±3.9).

Results

In the overall population, 25(OH)D is significantly inversely correlated with body mass index (BMI), systolic blood pressure (SBP), waist circumference (WC), fasting plasma glucose (FPG), insulin levels, and homeostasis model assessment of insulin resistance (HOMA index) and positively correlated with adiponectin and high density lipoprotein-cholesterol (P<0.01 for all variables). In males, these correlations are still significant for BMI, SBP, WC, and adiponectin (P=0.02,P=0.01,P=0.04 andP=0.01 respectively); also, 25(OH)D is inversely correlated with low density lipoprotein (LDL)-cholesterol (P=0.007). In females, 25(OH)D is only inversely correlated with FPG and HOMA index (P<0.001 andP=0.03 respectively). In multivariate regression analysis models, after adjustment for sex and BMI, 25(OH)D is an independent predictor of FPG and SBP (P=0.032 andP=0.05 respectively) in the overall population, while in males 25(OH)D is a predictor of LDL-cholesterol and SBP independently of BMI (P=0.007 andP=0.035 respectively).

Conclusion

In non-obese young subjects, we observe new relationships between 25(OH)D and several metabolic risk factors and adiponectin. Further research is needed to elucidate the gender differences and to look at the relation between 25(OH)D and adiponectin.
Obestatin/ghrelin cells in normal mucosa and endocrine tumours of the stomach
Authors: Tsolakis Apostolos V , Grimelius Lars , Stridsberg Mats , Falkmer Sture E , Waldum Helge L , Saras Jan , Janson Eva T
Published: March 2009

Objective

Obestatin and ghrelin are derived from the same gene and co-expressed in the same endocrine cells. Vesicular monoamine transporter-2 (VMAT-2), a marker for enterochromaffin-like (ECL) cells, is considered to be expressed in ghrelin cells. The aim was to establish if the two peptides and the transporter are co-expressed, both in normal gastric mucosa and in gastric endocrine tumours.

Design

An immunohistochemical study was performed on gastric biopsy material and on surgical specimens from 63 patients with gastric endocrine tumours and from individuals with normal gastric mucosa. Cells displaying obestatin immunoreactivity were examined regarding co-localization with ghrelin and VMAT-2. Both single- and double-immunostaining techniques were applied. Obestatin concentration in blood was measured in a subgroup of these patients. The results were correlated to various clinico-pathological parameters.

Results

In the normal mucosa, obestatin/ghrelin-immunoreactive cells rarely co-expressed VMAT-2. In most tumour tissue specimens, only a fraction of neoplastic cells displayed immunoreactivity to obestatin, and these cells always co-expressed ghrelin. Neoplastic obestatin-/ghrelin-IR cells invariably expressed VMAT-2, except for two ghrelinomas. The obestatin concentrations in blood were consistently low and did not correlate to clinico-pathological data.

Conclusions

Obestatin and ghrelin immunoreactivity always occurred in the same endocrine cells in the gastric mucosa but these cells only occasionally co-expressed VMAT-2, opposite to the findings in tumours. These results indicate that endocrine cells expressing obestatin and ghrelin mainly differ from VMAT-2 expressing cells (ECL-cells) and can develop into pure ghrelinomas. Plasma concentrations of obestatin did not correlate to cellular expression.
Radiation Damage Theory: Past, Present and Future
Authors: Barashev Alexander V. , Golubov Stanislav I.
Published: March 2009

Efforts of many scientists for more than a half of a century have resulted in substantial understanding of the response of various materials to irradiation. The theory has contributed significantly to this process but has not acquired a status allowing it to play a decisive role in creating radiation-resistant materials. Moreover, some theoretical predictions are in contradiction with observations, which indicates that something important has escaped attention. In the present paper, the current theoretical framework and experimental data are analyzed to elucidate the reasons for such a situation. A way of developing a predictive theory is proposed.
Multicomponent 5V Cathodes for Li-ion Batteries
Authors: Gulbinska Malgorzata K. , Ravdel Boris , Trebukhova Svetlana , Hult Brian N. , Mukerjee Sanjeev
Published: March 2009

In this study, the multicomponent electrode approach was used in an attempt to simultaneously improve the cell's specific energy values by shifting the cathode's voltage up to the 5V-region, combined with the increased specific capacity via addition of the second electrode component. The electrode materials were prepared by variety of synthetic methods (e.g. solid state, sol-gel, mechanical mixing etc.) and tested for lithium-ion intercalation properties. Structural properties and morphology of synthesized materials were characterized by X-ray diffraction (XRD) methods. The prospective 5V cathode materials were investigated as cathodes in the cells with lithium-metal counter electrode.
Formation of GaN Nanocrystal on Si and Its Photoelectrochemical Application
Authors: Fujii Katsushi , Kato Takashi , Sato Keiichi , Im In-Ho , Chang Ji-Ho , Yao Takafumi
Published: March 2009

GaN nanodots and nanorods were successfully grown on Si (111) substrates by molecular beam epitaxy. Photocurrent densities of GaN nanodots were quite small compared with thick GaN layer grown by metal-organic vapor phase epitaxy. The current density, however, increases with GaN nanodot density. The highest photocurrent density of the GaN nanodots was higher than that of the layer structure with similar thickness (up to 10 nm) to the nanodot height. GaN nanorods have much higher photocurrent density than that of GaN nanodots. Enough nanostructure size for light absorption is important to achieve good photoelectrochemical performance.
Nano-structured GeySi1-y:H Films Deposited by Low Frequency Plasma for Photovoltaic Application
Authors: Kosarev Andrey , Torres Alfonso , Zuniga Carlos , Adamo Marco , Sanchez Liborio
Published: March 2009

In this work we present the study of fabrication, Ge incorporation, structure and electronic properties of nano-structured GeySi1-y:H films with y>0.5 prepared by low frequency (LF) PECVD. GeySi1-y:H films were deposited by LF PECVD at a frequency f= 110 kHz from SiH4+GeH4+H2 gas mixture. SiH4 and GeH4 flows were varied to fabricate the films in wide range of 0<y<l. Hydrogen dilution was varied in the range of RH =20 to 80. Structure of the films was studied by AFM and SEM with consequent image processing to extract statistical parameters such as grain distribution and mean values. Composition of the films was characterized by SIMS and EDX. Electronic properties were characterized by temperature dependence of conductivity, spectral dependence of optical absorption. Sub-gap absorption was characterized by Urbach energy, EU; and defect absorption, αD. We observed grain like nano-structure with Gauss distribution of grain diameters by both AFM and SEM measurements. The most interesting films had mean grain diameter = 24.0±0.7 nm, dispersion D=11.0±0.2 nm and fill factor FF=0.313, Ge content y=0.96-0.97(by SIMS and EDS). These films showed also the lowest values of Urbach energy EU = 0.030 eV and low defect absorption αD = 5×102 cm −1 (at photon energy hv = 1.04 eV) indicating on low density of localized states in mobility gap. Doped films have been also fabricated and studied. Finally we shall discuss application of the above films in photovoltaic devices.
Surface Treatment of TiAl with Fluorine for Improved Performance at Elevated Temperatures
Authors: Donchev A. , Masset P.J. , Schütze M.
Published: March 2009

Alloys based on aluminium and titanium are possible materials for several high temperature applications. The use of TiAl would increase the efficiency of e.g. aero turbines, automotive engines and others due to their properties, among others low specific weight and good high temperature strength. The oxidation resistance is low at temperatures above approximately 800°C so that no long term use of TiAl-components is possible without improvement of the oxidation behaviour. Small amounts of halogens in the surface zone of TiAl-samples lead to a dramatic improvement of the oxidation resistance at temperatures up to 1100°C for more than 8000 hours in air. In this paper results of the work on the halogen effect over the last years are presented. The results of thermogravimetric measurements, thermocyclic oxidation tests of small coupons and thermodynamic calculations for different atmospheres (e.g. air, H2O, SO2) are shown and the halogen effect mechanism is discussed. The postulated mechanism is in good agreement with the results of the oxidation tests. The limits of the halogen effect will also be mentioned. Predictions for the halogenation of TiAl-components can be given so that the processing can be planned in advance.
The Potential Use of Vinegar and a Clove Oil Herbicide for Weed Control in Sweet Corn, Potato, and Onion
Authors: Evans G. J. , Bellinder R. R.
Published: March 2009

Natural products might provide an organic means of weed control. Our objective was to evaluate the potential use of vinegar and a clove-oil product with regard to how volume, concentration, and application timing affect weed control and crop response. Treatments included broadcast applications of 200- and 300-grain vinegar at 318 liters per hectare (L/ha), 150- and 200-grain vinegar at 636 L/ha, a 3.4% v/v clove oil mixture in water (318 L/ha), and a 1.7% clove oil mixture in 200-grain vinegar (318 L/ha). Field trials were conducted in sweet corn, onion, and potato. Weed control, weed biomass, crop injury, and yield data were collected. Corn treated at 15 and at 30 to 45 cm was initially burned and stunted by these products. By 4 wk after application much of the initial injury was outgrown. Late applications significantly reduced yields of early-maturing sweet corn ‘Trinity’. With the exception of the 200-grain vinegar (318 L/ha) treatment, early applications to sweet corn ‘Avalon’ did not reduce marketable yield. Two hundred-grain vinegar (636 L/ha) applied to pre-emergence–flag stage onion reduced the duration of the first handweeding by 59 to 67%. All treatments reduced onion yields when treated at the 2-leaf stage. Potato treated early (2 to 10 cm) and late (30 cm) were injured by all vinegar treatments 59 to 83%, 1 d after treatment (DAT). Potato yield losses were insignificant with applications of 3.4% clove oil and with some low-volume (318 L/ha) vinegar treatments. Product efficacy was dependent on the weed species and their size at the time of application. Weed control was greatest (83%, 1 DAT) with 200-grain vinegar (636 L/ha). Broadcast applications of vinegar and clove oil have potential for use on young, actively growing sweet corn, onion, and potato.
U.S. Grower Views on Problematic Weeds and Changes in Weed Pressure in Glyphosate-Resistant Corn, Cotton, and Soybean Cropping Systems
Authors: Kruger Greg R. , Johnson William G. , Weller Stephen C. , Owen Micheal D. K. , Shaw David R. , Wilcut John W. , Jordan David L. , Wilson Robert G. , Bernards Mark L. , Young Bryan G.
Published: March 2009

Corn and soybean growers in Illinois, Indiana, Iowa, Mississippi, Nebraska, and North Carolina, as well as cotton growers in Mississippi and North Carolina, were surveyed about their views on changes in problematic weeds and weed pressure in cropping systems based on a glyphosate-resistant (GR) crop. No growers using a GR cropping system for more than 5 yr reported heavy weed pressure. Over all cropping systems investigated (continuous GR soybean, continuous GR cotton, GR corn/GR soybean, GR soybean/non-GR crop, and GR corn/non-GR crop), 0 to 7% of survey respondents reported greater weed pressure after implementing rotations using GR crops, whereas 31 to 57% felt weed pressure was similar and 36 to 70% indicated that weed pressure was less. Pigweed, morningglory, johnsongrass, ragweed, foxtail, and velvetleaf were mentioned as their most problematic weeds, depending on the state and cropping system. Systems using GR crops improved weed management compared with the technologies used before the adoption of GR crops. However, the long-term success of managing problematic weeds in GR cropping systems will require the development of multifaceted integrated weed management programs that include glyphosate as well as other weed management tactics.
Dose–Response Curves of KIH-485 for Preemergence Weed Control in Corn
Authors: Knezevic Stevan Z. , Datta Avishek , Scott Jon , Porpiglia Peter J.
Published: March 2009

Field experiments were conducted in Nebraska with the experimental herbicide KIH-485 on soils with three different levels of organic matter (OM) to ascertain a dose response for weed control and corn tolerance. Dose–response curves based on the log-logistic model were used to determine the effective dose that provides 90% weed control (ED90 values) for three grasses (green foxtail, field sandbur, large crabgrass) and two broadleaf weeds (velvetleaf, tall waterhemp). The ED90 values for green foxtail control were 143, 165, and 202 g ai/ha for soils with 1, 2, and 3% OM, respectively at 28 d after treatment (DAT). The highest dose of 371 g ai/ha was needed for field sandbur control at 28 DAT, compared with 141 g ai/ha for large crabgrass, 152 g ai/ha for tall waterhemp, and 199 g ai/ha for velvetleaf. There was no significant corn injury observed. Grain yield increased with increasing doses of KIH-485; optimum yield was achieved at about 195 g ai/ha. From the dose–response curves it is clear that the proposed label rate of KIH-485 of 200 to 300 g ai/ha will provide excellent control of most grasses and certain broadleaf weeds in corn for at least the first 4 wk of the growing season on soils up to 3% OM in the state of Nebraska.
Modelling of space–time rainfall for three UK regions
Authors: Segond M.-L. , Onof C.
Published: March 2009

In the context of flood management in urban areas in the UK, the Gaussian displacement spatial–temporal model (GDSTM) is used to generate a continuous rainfall field. The model makes the assumption that storms arrive according to a Poisson process in space and time, triggering another Poisson process of cell arrivals over the storm duration. These cells are displaced from the storm centre according to a normal distribution. Historic rainfall events are identified from a 3·5-year record of Met Office weather radar data from three different radars and the characteristics of the interior of each event are represented by 11 parameters. The process of event arrival is described by six additional parameters. For each month within the radar data record, a library of model parameters is obtained and used to develop simulations of 100 years of continuous, spatially varying rainfall at 5 min intervals and 1 km spatial resolution over three regions: London, Bradford and Glasgow. The objective is to use the synthetic data as input to existing urban drainage models to examine system performance. It is possible to reproduce standard statistics over the London region but the extreme values are underestimated when compared with statistics from the Flood Estimation Handbook (FEH). The mean rainfall is overestimated at the other sites but more agreement in simulating the extremes is observed when compared with the FEH.
Radar-based flood forecasting for river catchments
Authors: Reichel F. , Verworn H.-R. , Krämer S. , Cluckie I. , Rico-Ramirez M. A.
Published: March 2009

Weather radars provide high resolution in space and time and thus deliver distributed rainfall information. They therefore have high potential for exploitation in real-time flood forecasting. However, several aspects limit the accuracy of such data in flood forecasting systems. A major aspect is associated with the error included in the radar data and the limited lead time. To assess real-time flood forecasts and improve their reliable lead times with radar rainfall data, this paper presents a framework for a radar-based flood forecasting model integrating radar rainfall data, geographical information systems, the hydrological model HEC—HMS and a short-term precipitation nowcasting system. The benefit of the radar-based flood forecast is analysed and the limits of predictability due to the meteorological aspects of the rainfall forecast as well as the hydrological model are investigated. The incorporation of the radar-based rainfall forecast demonstrates good potential for successful hydrological modelling and prediction.
Differences in multi-sensor and rain-gauge precipitation amounts
Authors: Westcott N. E.
Published: March 2009

A comparison of multi-sensor (radar and gauge) and gauge precipitation estimates at a monthly temporal resolution and a county spatial resolution was undertaken for the midwestern USA. Precipitation data were collected from February 2002 to October 2006 from two sources: (a) multi-sensor precipitation estimates (MPE) based on the stage III/IV algorithm developed by the US National Oceanic and Atmospheric Administration (NOAA), national weather service (NWS) office of hydrology and NWS river forecast centres; and (b) quality-controlled NWS cooperative rain-gauge (QC_Coop) data from the NOAA national climatic data centre (NCDC). The gauge data were employed as the reference standard. The monthly median of the percentage differences in county-averaged monthly precipitation estimated by MPE and QC_Coop in the midwestern USA, for around 750 counties, was mainly within ±12·5%, with a median percentage difference of +6%. The positive difference indicates that, overall, the MPE values tend to be smaller than the QC_Coop values. ME values more closely correspond with QC_Coop values at all latitudes in the summer months when convective precipitation is dominant, and in the winter months for latitudes where non-frozen precipitation is most prevalent.
Cinrad data quality control and precipitation estimation
Authors: Chen Y. , Zou Q. , Han J. , Cluckie I.
Published: March 2009

Cinrad is the acronym describing China's next-generation weather radar that inherits the technology of the US national weather system Nexrad (WSR-88D) through a joint agreement between the two countries. More than 100 Cinrad systems have currently been deployed in China, but challenges exist for their wider application. The data quality assessment and the development of quantitative precipitation estimation for flood risk management will pose a significant challenge as the national system is both commissioned and further developed. This paper is based on an assessment of the data quality of a Cinrad system deployed in southern China and describes aspects of the initial data quality-control procedure. Precipitation was estimated for the Liuxihe River basin using 11 observed storms. The data quality-control procedure presented in this paper has four components, including volume-scan data, missing-data interpolation, abnormal-reflectivity detection and correction and fine-day reflectivity removal. The results indicate that the radar-estimated precipitation is consistent with that measured by conventional rain-gauge networks; also radar estimated precipitation can provide a better representation of the spatial distribution of the precipitation over the whole basin, and thereby has the potential to improve flood forecasting and warning systems. Given the importance of flooding to China, the continued quantitative development of the radar system is of national importance, particularly in terms of the tropical-cyclone-induced flooding prevalent in south China.