bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dusp-5 and Snrk-1 coordinately function during vascular development and disease
Authors: Pramanik Kallal , Chun Chang Zoon , Garnaas Maija K. , Samant Ganesh V. , Li Keguo , Horswill Mark A. , North Paula E. , Ramchandran Ramani 
Published: October 2008

AbstractMitogen-activated protein kinases play an integral role in several cellular processes. To regulate mitogen-activated protein kinases, cells express members of a counteracting group of proteins called phosphatases. In this study, we have identified a specific role that one member of this family of phosphatases, dual-specific phosphatase-5 (Dusp-5) plays in vascular development in vivo. We have determined that dusp-5 is expressed in angioblasts and in established vasculature and that it counteracts the function of a serine threonine kinase, Snrk-1, which also plays a functional role in angioblast development. Together, Dusp-5 and Snrk-1 control angioblast populations in the lateral plate mesoderm with Dusp-5 functioning downstream of Snrk-1. Importantly, mutations in dusp-5 and snrk-1 have been identified in affected tissues of patients with vascular anomalies, implicating the Snrk-1–Dusp-5 signaling pathway in human disease.
A novel screening protocol for the isolation of hydrogen producing Chlamydomonas reinhardtiistrains
Authors: Rühle Thilo , Hemschemeier Anja , Melis Anastasios , Happe Thomas 
Published: October 2008

Abstract

Background
Sealed Chlamydomonas reinhardtii cultures evolve significant amounts of hydrogen gas under conditions of sulfur depletion. However, the eukaryotic green alga goes through drastic metabolic changes during this nutritional stress resulting in cell growth inhibition and eventually cell death. This study aimed at isolating C. reinhardtii transformants which produce hydrogen under normal growth conditions to allow a continuous hydrogen metabolism without the stressful impact of nutrient deprivation.

Results
To achieve a steady photobiological hydrogen production, a screening protocol was designed to identify C. reinhardtii DNA insertional mutagenesis transformants with an attenuated photosynthesis to respiration capacity ratio (P/R ratio). The screening protocol entails a new and fast method for mutant strain selection altered in their oxygen production/consumption balance. Out of 9000 transformants, four strains with P/R ratios varying from virtually zero to three were isolated. Strain apr1 was found to have a slightly higher respiration rate and a significantly lower photosynthesis rate than the wild type. Sealed cultures of apr1 became anaerobic in normal growth medium (TAP) under moderate light conditions and induced [FeFe]-hydrogenase activity, yet without significant hydrogen gas evolution. However, Calvin-Benson cycle inactivation of anaerobically adapted apr1 cells in the light led to a 2-3-fold higher in vivo hydrogen production than previously reported for the sulfur-deprived C. reinhardtii wild type.

Conclusion
Attenuated P/R capacity ratio in microalgal mutants constitutes a platform for achieving steady state photobiological hydrogen production. Using this platform, algal hydrogen metabolism can be analyzed without applying nutritional stress. Furthermore, these strains promise to be useful for biotechnological hydrogen generation, since high in vivo hydrogen production rates are achievable under normal growth conditions, when the photosynthesis to respiration capacity ratio is lowered in parallel to down regulated assimilative pathways.
Characterization and Putative Role of a Type I Gonadotropin-Releasing Hormone in the Cephalochordate Amphioxus
Authors: Chambery Angela , Parente Augusto , Topo Enza , Garcia-Fernàndez Jordi , D'Aniello Salvatore 
Published: October 2008

GnRH, originally isolated from mammalian hypothalamus, is a key player in the control of vertebrate reproduction. Employing reverse-phase chromatography, we purified a peptide of relative molecular mass of 1182.60 Da from the cephalochordate amphioxus Branchiostoma lanceolatum. We found that its amino acid sequence (pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2) was identical to that of mammalian GnRH. The highest concentrations (4.04 ± 0.3 μg/g tissue), localized in the anterior part of the body, occurred in November, a time when amphioxus gonads prepare for the seasonal spawning. Furthermore, the biological activity of amphioxus GnRH was investigated by examining its capability to elicit LH release from the rodent pituitary gland. The origins of GnRH can be traced back to the origins of chordates. The seasonal variations of amphioxus GnRH also suggest an ancient role of this peptide in the control of reproduction in chordates, even before the evolution of a proper pituitary gland.Data show that the isolation of a GnRH hormone in the cephalochordate Amphioxus could have a pivotal role in reproduction.
To break a coralline: mechanical constraints on the size and survival of a wave-swept seaweed
Authors: Martone Patrick T. , Denny Mark W. 
Published: October 2008

SUMMARY
Previous studies have hypothesized that wave-induced drag forces may constrain the size of intertidal organisms by dislodging or breaking organisms that exceed some critical dimension. In this study, we explored constraints on the size of the articulated coralline alga Calliarthron, which thrives in wave-exposed intertidal habitats. Its ability to survive depends critically upon its segmented morphology (calcified segments separated by flexible joints or `genicula'), which allows otherwise rigid fronds to bend and thereby reduce drag. However, bending also amplifies stress within genicula near the base of fronds. We quantified breakage of genicula in bending by applying known forces to fronds until they broke. Using a mathematical model, we demonstrate the mitigating effect of neighboring fronds on breakage and show that fronds growing within dense populations are no more likely to break in bending than in tension, suggesting that genicular morphology approaches an engineering optimum, possibly reflecting adaptation to hydrodynamic stress. We measured drag in a re-circulating water flume(0.23–3.6 m s–1) and a gravity-accelerated water flume,which generates jets of water that mimic the impact of breaking waves(6–10 m s–1). We used frond Reynolds number to extrapolate drag coefficients in the field and to predict water velocities necessary to break fronds of given sizes. Laboratory data successfully predicted frond sizes found in the field, suggesting that, although Calliarthron is well adapted to resist breakage, wave forces may ultimately limit the size of intertidal fronds.
Hydrodynamics of the escape response in bluegill sunfish,Lepomis macrochirus
Authors: Tytell Eric D. , Lauder George V. 
Published: October 2008

SUMMARYEscape responses of fishes are one of the best characterized vertebrate behaviors, with extensive previous research on both the neural control and biomechanics of startle response performance. However, very little is known about the hydrodynamics of escape responses, despite the fact that understanding fluid flow patterns during the escape is critical for evaluating how body movement transfers power to the fluid, for defining the time course of power generation, and for characterizing the wake signature left by escaping fishes, which may provide information to predators. In this paper, we present an experimental hydrodynamic analysis of the C-start escape response in bluegill sunfish (Lepomis macrochirus). We used time-resolved digital particle image velocimetry at 1000 frames s–1 (fps)to image flow patterns during the escape response. We analyzed flow patterns generated by the body separately from those generated by the dorsal and anal fins to assess the contribution of these median fins to escape momentum. Each escape response produced three distinct jets of fluid. Summing the components of fluid momentum in the jets provided an estimate of fish momentum that did not differ significantly from momentum measured from the escaping fish body. In contrast to conclusions drawn from previous kinematic analyses and theoretical models, the caudal fin generated momentum that opposes the escape during stage one, whereas the body bending during stage one contributed substantial propulsive momentum. Additionally, the dorsal and anal fins each contributed substantial momentum. The results underscore the importance of the dorsal and anal fins as propulsors and suggest that the size and placement of these fins may be a key determinant of fast start performance.
Pore-Water Pressure Buildup in Clean Sands Because of Cyclic Straining
Authors: Ladd RS , Dobry R , Dutko P , Yokel FY , Chung RM 
Published: October 2008

Abstract
The prediction of pore-water pressure buildup in sands caused by undrained cyclic loading is one of the key items in evaluating the potential for liquefaction of sandy sites during earthquakes. Presented herein are data indicating that, in strain-controlled tests, there is a predictable correlation between cyclic shear strain, number of cycles, and pore-water pressure buildup; this correlation is much less sensitive to factors, such as relative density and fabric than comparable results obtained from stress-controlled tests. Also, there is a threshold cyclic shear strain below which there is no sliding at the contacts between sand particles, and essentially no pore-water pressure buildup occurs. The data indicate that, for clean sands, this threshold shear strain, as well as the pore-water pressure buildup for strains slightly above the threshold, are basically independent of relative density, grain size distribution, fabric, and method of testing (triaxial and direct simple shear). However, both threshold shear strain and pore-water pressure buildup do depend on the overconsolidation ratio.
Laboratory Testing of Chemically Grouted Sand
Authors: Christopher BR , Atmatzidis DK , Krizek RJ 
Published: October 2008

Abstract
The effect of 14 parameters, associated with specimen preparation, handling, and testing, and with soil characteristics, was evaluated experimentally for laboratory prepared specimens of chemically grounted sands. Over 200 unconfined compression tests were conducted, and results are presented and comparisons are made in terms of unconfined compressive strength and tangent modulus at 50% of maximum stress. Curing environment, curing time, specimen size, grain size, and grain size distribution are the parameters that affect significantly the observed mechanical behavior of grouted sands. The results of this study were used in the development of ASTM Laboratory Preparation of Chemically Grouted Soil Specimens for Obtaining Design Strength Parameters (D 4320).
Hollow Cylinder Tests on Natural Rock Salt
Authors: Senseny PE , Mellegard KD , Wagner LA 
Published: October 2008

Abstract
Constitutive equations for the thermomechanical behavior of salt must accurately model material behavior when all three principal stresses are independent. Conventional triaxial compression and extension tests measure material response for stress states in which two of the principal stresses are equal. A computer-controlled, servohydraulic system is described for testing hollow cylinder specimens at stress states in which the principal stresses are controlled independently. Results of validation tests are given to show that the test system provides accurate measurements of the behavior of salt.
Studies with Centrifuge Vane and Penetrometer Apparatus in a Normal Gravity Field
Authors: Davies MCR , Almeida MSS , Parry RHG 
Published: October 2008

Abstract
Small vane and penetrometer devices have been developed to measure soil properties in models during centrifuge operation. To aid the interpretation of vane data from centrifuge models a series of tests was conducted in cakes of kaolin clay in a normal gravity field. In the experimental program the effects of disturbance during insertion, delay between insertion and rotation, rate of rotation and geometry of vane blades were investigated. The results were used to devise a scientific method of operation of the vane apparatus. Subsequent tests were all performed with a vane size of 18 mm diameter by 14 mm high. Penetrometer tests were conducted in cakes of kaolin and Gault clays. Vane shear strengths were used to calibrate the apparatus. The ratio of cone resistance to vane strength was found to increase with increasing over-consolidation ratio. The values also differed considerably between the two clays. Thus, while the penetrometer has the advantage of providing a continuous profile of resistance with depth, some care is required in converting this measurement into undrained shear strength.
Catching the Elusive Water-Cement Ratio Using Petrographic Methods—and Their Evaluation
Authors: Erlin Bernard 
Published: October 2008

AbstractPetrographers use a variety of techniques for estimating the w/c and w/cm of hardened concrete. The estimates are routinely accepted by the concrete industry. Generally, four general methods are popular today: (1) water-droplet absorption; (2) scratch hardness; (3) combination of 12 or so microscopical and physical observations of the paste; and (4) methods where thin sections of concrete are impregnated with blue- or fluorescent-dyed epoxy. Sometimes combinations are used. There are few specific details in the literature for assessing the precision of the w/c using these methods except for the fluorescence technique, where there has been controversy about its claimed accuracy. The degree of interpretation of data from each method is based upon the comfort of petrographers in extending their expertise to provide that estimate. The deftness, skill, and experience of the petrographers will usually dictate their comfort zone. However, sometimes confounding that estimate is the existing concrete condition. The acceptability of the petrographic estimates depends on: (1) competency of the petrographer; (2) validity of the technique(s) used; (3) ability of the petrographer to qualify the techniques used; (4) the purpose(s) to which the data will be used; and (5) needs of those who either want to accept the estimates or debunk the estimates—for whatever reason.
Contribution of Thermodynamic Calculations to Metallurgical Studies of Multi-Component Zirconium Based Alloys
Authors: Toffolon-Masclet C. , Brachet J. C. , Servant C. , Joubert J. M. , Barberis P. , Dupin N. , Zeller P. 
Published: October 2008

Abstract
The Zircobase thermodynamic database for zirconium alloys coupled with Thermo-Calc software represents a powerful tool for prediction of thermodynamic and metallurgical data such as activities, formation enthalpies, phase transformation temperatures, solubility limits, existence temperature range, and chemical compositions of second phase precipitates. This database was built up with binary and ternary descriptions assessed according to the CALPHAD methodology. It is sometimes necessary to take into account new systems, but also new versions of binary descriptions as recently experienced. For example, the two binary systems Zr-Fe and Zr-Sn had to be updated in order to fit new experimental results believed to be more accurate than previously available.
This paper aims at showing the improvements of the database taking into account new descriptions of binary systems, as also ternary description such as Zr-Fe-Cr, Zr-Fe-Ni, and Zr-Nb-Fe. For this last ternary system, new experimental data were necessary. New experimental study of the two ternary phases, hexagonal Zr(Nb,Fe)2 and cubic (Zr,Nb)4Fe2, allowed their crystal structures (P63/mmc and Fd3¯m, respectively) to be checked. This was useful to build up a sublattice model giving account of the existence of a composition range for these two intermetallic phases. Moreover, several specific ZrNbFe alloys were fabricated and annealed for times ranging from 1000 h to 10,000 h at 550, 700, 800, and 900°C to determine the equilibrium binary and ternary phase domains as a function of the temperature. All these data were used to obtain an improved thermodynamic modelling of this system. Finally, we illustrate some thermodynamic predictions of the different phases evolutions as a function of the temperature on multi-alloyed industrial type alloys. These examples show quite good agreement between the thermodynamic predictions and the experimental data derived from calorimetric experiments and microstructural observations.
ZIRLOTM Cladding Improvement
Authors: Foster John Paul , Yueh H. Ken , Comstock Robert J. 
Published: October 2008

Abstract
Improvements to fuel design have been made in recent years to meet the challenges of increases in fuel duty in terms of linear power and operating temperature. Improved cladding material is one of these design improvements. Specifically, Westinghouse has developed an improved version of ZIRLOTM called Optimized ZIRLO and denoted as OPT ZIRLO. The Sn level in this improved material is reduced from the nominal standard previous level of about 1 % to a range of 0.6 % to 0.8 %. The reduced Sn level has been optimized to produce a higher corrosion resistance and provide adequate in-reactor creep resistance. Out-reactor diameter creep tests have shown that decreasing Sn increases out-reactor creep, suggesting that decreasing Sn may also increase in-reactor creep. An in-reactor testing program in the Vogtle Unit 2 pressurized water reactor (PWR) was performed to confirm the predicted in-reactor behavior. The test samples were suspended as segmented rods inside fuel assembly thimble tubes. In-reactor diameter creep data confirmed that decreasing Sn increases in-reactor creep. As a result of the correlation between in-reactor and out-reactor creep, an extensive out-reactor diameter creep program was performed in order to develop methods to fabricate OPT ZIRLO with the same in-reactor creep properties as the currently used stress-relief annealed standard ZIRLO (denoted as SRA STD ZIRLO). The level of in-reactor diameter creep of SRA STD ZIRLO was achieved for OPT ZIRLO by two methods. One method involved changing the final microstructure from SRA to partially recrystallized (PRXA). The other method kept the final microstructure as SRA and changed the tube reduction sequence to decrease the final tube area reduction. In order to develop these methods, a series of material variation tests was performed. Some of the material variations included different final heat treatments, different tube reduction sequences, and different pre-charged hydrogen levels. These tests were performed for both out-reactor and in-reactor. In addition, the out-reactor and in-reactor creep were observed to directly correlate for OPT ZIRLO material fabricated with different final anneal temperatures. Thus, out-reactor creep may be used to predict in-reactor creep properties for different final anneal temperatures. These results show that fabrication changes may be used to control in-reactor creep. In this study, fabrication changes were used to compensate for the reduction in in-reactor creep strength associated with lower tin content in OPT ZIRLO.
Computer Simulation of Consecutive Ski Turns
Authors: Mössner Martin , Heinrich Dieter , Kaps Peter , Schretter Herwig , Nachbauer Werner 
Published: October 2008

Abstract
A computer model was developed to simulate consecutive ski turns. The model consists of a segment model for two skis and a single body for the skier. It was implemented in the multibody simulation software LMS Virtual.Lab. The interaction of ski and snow leads to a normal and a shearing force. For the normal force a hypoplastic relation between force and penetration depth was used. Hypoplasticity considers the effect that compacted snow is inelastic and deformations remain. For the shearing force orthogonal metal cutting theory was applied. During turns the skier has to keep balance. He leans inward to compensate centrifugal force. Neglecting angulation the complement of the inward lean angle is the mean value of the edge angles of the left and the right ski. With a suitable choice of the edge angles the skier kept the balance. Using this model the trajectory of the skier was simulated over four and a half turns. The first turn was rather carved, but in the last turn strong skidding was present. Due to increasing speed the centrifugal force considerably exceeded the shearing strength of snow. The hypoplastic force-penetration relation led to a reasonable penetration depth, which is a crucial factor for the shearing force. Based on this reference simulation the influence of edge angle and forward/backward lean was assessed by performing parameter studies. An increased edge angle caused smaller turn radii. Surprisingly, forward lean caused larger and backward lean smaller turn radii. This phenomenon could be explained by the turn moment of the skier. Both effects were more dominant when the skis skidded.
Kinetics and Reaction Products of Ozone and Surface-Bound Squalene
Authors: Wells J. R. , Morrison Glenn C. , Coleman Beverly K. 
Published: October 2008

Abstract
Because of the high occupant density in aircraft, the surface chemistry of ozone and squalene, an important component of skin oil, was evaluated. A reaction probability of (45±14)×10−5 was determined for the reaction of squalene (2,6,10,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene) with ozone (50 parts per billion (ppb)) on a glass plate surface using the Field and Laboratory Emission Cell (FLEC) Automation and Control System (FACS). To more clearly define part of squalene’s indoor environment degradation mechanism, gas-phase and surface-bound products of the squalene+O3 reaction were also investigated. Emitted products were captured in solution, derivatized with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA), and analyzed by gas chromatography and ion trap mass spectroscopy. The identified squalene+O3 reaction products were: 6-methyl-5-hepten-2-one (6MHO, ((CH3)2CCH(CH2)2 C(O)CH3)), glyoxal (ethanedial, HC(O)C(O)H), 4-oxopentanal (4OPA, CH3C(O)CH2CH2 CH(O)), and 6,10-dimethylundeca-5,9-dien-2-one (geranyl acetone). The compound 5,9,13-trimethyltetradeca-4,8,12-trienal is proposed as the other major squalene+O3 reaction product. This compound was determined from mass spectrometry coupled with plausible squalene+O3 reaction mechanisms based on previously published volatile organic compound+O3 gas-phase reaction mechanisms.