bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence that Corticotropin-Releasing Hormone Modulates Myometrial Contractility during Human Pregnancy
Authors: Tyson Elisa K. , Smith Roger , Read Mark
Published: October 2009

As human pregnancy advances, CRH increases exponentially and is hypothesized to trigger the transition from myometrial quiescence to active contractions at labor. Paradoxically, CRH stimulates cAMP production, suggesting it should cause relaxation. To evaluate CRH as a mediator of quiescence, the effect of CRH on contractions in preterm and term myometria with concurrent progesterone (P4) was determined. In late gestation, we hypothesized that high concentrations of CRH down-regulate agonist-activated-cAMP relaxatory pathways and that increased phosphodiesterase (PDE) activity induces heterologous down-regulation of agonist-activated-cAMP pathways. CRH caused dose-dependent relaxation of spontaneously contracting myometrial strips of 31 ± 8% (mean ± sem; n = 12) and 35 ± 20% (n = 3) in term and preterm samples, respectively. CRH with P4 pretreatment caused a 40 ± 13% (n = 4) reduction in contractility, whereas in matched samples, CRH alone exerted a 26 ± 6% (n = 4) reduction, with a shift of CRH dose-response curves (P < 0.01, ANOVA). Pretreatment of strips with 10−7m CRH did not attenuate relaxation induced by subsequent CRH (n = 3) or salbutamol (β2-agonist) treatment (n = 9). PDE inhibition by rolipram showed a 2.2- and 1.5-fold increase in maximal relaxation induced by CRH and salbutamol, respectively, with a shift of both dose-response curves (P < 0.05 and P < 0.01, ANOVA). In conclusion, CRH at physiological concentrations acts synergistically with P4 contributing to myometrial quiescence. P4 withdrawal may reduce CRH-mediated relaxation. Our functional model does not support homologous or heterologous down-regulation of agonist-stimulated-cAMP pathways by high CRH concentrations. PDE inhibition potentiates CRH and salbutamol-induced relaxation. Up-regulation of PDEs, through chronic cAMP elevation by CRH, could provide a mechanism for down-regulation of agonist-stimulated-cAMP pathways at term.
The Spontaneous Ala147Thr Amino Acid Substitution within the Translocator Protein Influences Pregnenolone Production in Lymphomonocytes of Healthy Individuals
Authors: Costa Barbara , Pini Stefano , Gabelloni Pamela , Da Pozzo Eleonora , Abelli Marianna , Lari Lisa , Preve Matteo , Lucacchini Antonio , Cassano Giovanni B. , Martini Claudia
Published: October 2009

The de novo production of steroids and neurosteroids begins in mitochondria by the conversion of cholesterol to pregnenolone through cytochrome P450 side-chain cleavage (CYP11A1) enzymatic activity. The C-terminal amino acid domain of the translocator protein (TSPO) has been demonstrated to bind cholesterol, thereby determining its mitochondrial translocation. The goal of the present study was to investigate the effect of the Ala147Thr single-nucleotide polymorphism localized in this TSPO region on pregnenolone production in healthy volunteers. Pregnenolone production was evaluated in a peripheral cell model, represented by circulating lymphomonocytes. First, CYP11A1 expression, both at mRNA and protein level, was demonstrated. Pregnenolone production varied among genotype groups. Comparison of pregnenolone mean values revealed that Thr147 homozygous or heterozygous individuals had significantly lower pregnenolone levels compared with Ala147 homozygous individuals. These findings suggested a dominant effect of the minor allelic variant Thr147 to produce this first metabolite of the steroidogenesis pathway. Interestingly, Ala147 homozygous individuals exhibited significant higher levels of circulating cholesterol-rich low-density lipoproteins with respect to heterozygous individuals. In conclusion, our results demonstrate that the Ala147Thr spontaneous amino acid substitution within TSPO is able to affect pregnenolone production; this should encourage further studies to investigate its potential role in polygenic dyslipidemias.
Circulating and Adipose Tissue Gene Expression of Zinc-α2-Glycoprotein in Obesity: Its Relationship with Adipokine and Lipolytic Gene Markers in Subcutaneous and Visceral Fat
Authors: Ceperuelo-Mallafré V. , Näf S. , Escoté X. , Caubet E. , Gomez J. M. , Miranda M. , Chacon M. R. , Gonzalez-Clemente J. M. , Gallart L. , Gutierrez C. , Vendrell J.
Published: October 2009

Context: Zinc-α2-glycoprotein (ZAG) is a soluble protein similar to the class I major histocompatibility complex heavy chain, which has been implicated in lipid catabolism. We hypothesized that ZAG mRNA expression in adipose tissue may be linked with lipolytic and adipokine gene expression and have a close relationship with clinical phenotype.

Objectives: The objective of the study was to analyze ZAG gene expression in human adipose tissue from lean and obese subjects. ZAG circulating plasma levels and its relationship with cardiometabolic risk factors were also studied.

Design: Seventy-three Caucasian (43 male and 30 female) subjects were included. Plasma and adipose tissue [sc (SAT) and visceral (VAT)] from the same patient were studied. mRNA of PPARγ, hormone-sensitive lipase (HSL), adipose triglyceride lipase, adiponectin, omentin, visfatin, and ZAG were quantified. Plasma concentrations of ZAG were determined with ELISA.

Results: ZAG plasma levels showed a negative correlation with insulin (r = −0.39; P = 0.008) and the homeostasis model assessment for insulin resistance index (r = −0.36; P = 0.016). No differences in ZAG circulating levels according to body mass index classification were observed.

ZAG expression in SAT was significantly reduced in overweight and obese individuals compared with lean subjects (P < 0.001 and P = 0.007, respectively). ZAG mRNA expression in both SAT and VAT depots were negatively correlated with many clinical and metabolic cardiovascular risk factors. After multiple linear regression analysis, SAT ZAG was mainly predicted by adiponectin mRNA expression (B = 0.993; P < 0.0001) and plasma triglyceride levels (B = −0.565; P = 0.006). VAT ZAG expression was predicted by adiponectin expression (B = 0.449; P < 0.0001), and HSL VAT expression (B = 0.180; P = 0.023).

Conclusions: The present study provides evidence of a role of ZAG gene in adipose tissue metabolism, with a close association with adiponectin gene expression in sc and visceral fat.
Prenatal Determinants of Uterine Volume and Ovarian Reserve in Adolescence
Authors: Hart Roger , Sloboda Deborah M. , Doherty Dorota A. , Norman Robert J. , Atkinson Helen C. , Newnham John P. , Dickinson Jan E. , Hickey Martha
Published: October 2009

Context: Adequate uterine volume and ovarian reserve are essential for reproductive health. Antenatal events such as restricted fetal growth and maternal tobacco smoking are hypothesized to impact on reproductive function in later life, although not studied in a large prospective normal pregnancy population to date.

Objective: The objective of the study was to determine the relationship between intrauterine growth, birth weight, and maternal tobacco smoking on uterine volume and ovarian reserve in adolescence.

Design and Setting: This was a prospective study in which half the cohort underwent intensive ultrasound monitoring in utero.

Participants: Intrauterine growth was measured using ultrasound at 18, 24, 28, and 34/36 wk gestation (n = 115 girls). Maternal smoking data were prospectively collected at 18 and 34/36 wk from the whole cohort. Uterine (n = 229) and early follicular ovarian volume and antral follicle count (n = 225) were measured using transabdominal ultrasound (n = 230). Ovarian reserve was estimated using early follicular phase anti-Mullerian hormone, inhibin B, and FSH (n = 213).

Main Outcome Measures: The relationship between maternal tobacco smoking, intrauterine growth trajectories, and markers of ovarian reserve and uterine size in adolescence was measured.

Results: Linear regression showed that daughters of mothers who smoked had a significantly smaller uterus compared with nonsmokers (P = 0.019). No significant relationship between maternal tobacco smoking and ovarian volume (P = 0.164) or markers of ovarian reserve (antral follicle count, plasma FSH, anti-Mullerian hormone, and inhibin B) in adolescence was determined.

Conclusions: Our findings indicate that maternal smoking, but not variations in fetal growth, may lead to a reduction in uterine volume and does not appear to impact ovarian reserve.
Regulation of GPR54 Signaling by GRK2 and β-Arrestin
Authors: Pampillo Macarena , Camuso Natasha , Taylor Jay E. , Szereszewski Jacob M. , Ahow Maryse R. , Zajac Mateusz , Millar Robert P. , Bhattacharya Moshmi , Babwah Andy V.
Published: October 2009

Kisspeptin and its receptor, GPR54, are major regulators of the hypothalamic-pituitary-gonadal axis as well as regulators of human placentation and tumor metastases. GPR54 is a Gq/11-coupled G protein-coupled receptor (GPCR), and activation by kisspeptin stimulates phosphatidy linositol 4, 5-biphosphate hydrolysis, Ca2+ mobilization, arachidonic acid release, and ERK1/2 MAPK phosphorylation. Physiological evidence suggests that GPR54 undergoes agonist-dependent desensitization, but underlying molecular mechanisms are unknown. Furthermore, very little has been reported on the early events that regulate GPR54 signaling. The lack of information in these important areas led to this study. Here we report for the first time on the role of GPCR serine/threonine kinase (GRK)2 and β-arrestin in regulating GPR54 signaling in human embryonic kidney (HEK) 293 cells, a model cell system for studying the molecular regulation of GPCRs, and genetically modified MDA MB-231 cells, an invasive breast cancer cell line expressing about 75% less β-arrestin-2 than the control cell line. Our study reveals that in HEK 293 cells, GPR54 is expressed both at the plasma membrane and intracellularly and also that plasma membrane expression is regulated by cytoplasmic tail sequences. We also demonstrate that GPR54 exhibits constitutive activity, internalization, and association with GRK2 and β- arrestins-1 and 2 through sequences in the second intracellular loop and cytoplasmic tail of the receptor. We also show that GRK2 stimulates the desensitization of GPR54 in HEK 293 cells and that β-arrestin-2 mediates GPR54 activation of ERK1/2 in MDA-MB-231 cells. The significance of these findings in developing molecular-based therapies for treating certain endocrine-related disorders is discussed.
Synergistic effect of aptamers that inhibit exosites 1 and 2 on thrombin
Authors: Nimjee Shahid M. , Oney Sabah , Volovyk Zoya , Bompiani Kristin M. , Long Steve B. , Hoffman Maureane , Sullenger Bruce A.
Published: October 2009

Thrombin is a multifunctional protease that plays a key role in hemostasis, thrombosis, and inflammation. Most thrombin inhibitors currently used as antithrombotic agents target thrombin's active site and inhibit all of its myriad of activities. Exosites 1 and 2 are distinct regions on the surface of thrombin that provide specificity to its proteolytic activity by mediating binding to substrates, receptors, and cofactors. Exosite 1 mediates binding and cleavage of fibrinogen, proteolytically activated receptors, and some coagulation factors, while exosite 2 mediates binding to heparin and to platelet receptor GPIb-IX-V. The crystal structures of two nucleic acid ligands bound to thrombin have been solved. Previously Padmanabhan and colleagues solved the structure of a DNA aptamer bound to exosite 1 and we reported the structure of an RNA aptamer bound to exosite 2 on thrombin. Based upon these structural studies we speculated that the two aptamers would not compete for binding to thrombin. We observe that simultaneously blocking both exosites with the aptamers leads to synergistic inhibition of thrombin-dependent platelet activation and procoagulant activity. This combination of exosite 1 and exosite 2 inhibitors may provide a particularly effective antithrombotic approach.
Solving the Order-Preserving Submatrix Problem via Integer Programming
Authors: Trapp Andrew C. , Prokopyev Oleg A.
Published: October 2009

In this paper we consider the order-preserving submatrix (OPSM) problem. This problem is known to be NP-hard. Although in recent years some heuristic methods have been presented to find OPSMs, they lack the guarantee of optimality. We present exact solution approaches based on linear mixed 0–1 programming formulations and develop algorithmic enhancements to aid in solvability. Encouraging computational results are reported both for synthetic and real biological data. In addition, we discuss theoretical computational complexity issues related to finding fixed patterns in matrices.
Freedom of Privacy: Anonymous Data Collection with Respondent-Defined Privacy Protection
Authors: Kumar Rajeev , Gopal Ram , Garfinkel Robert
Published: October 2009

The massive amount of sensitive survey data about individuals that agencies collect and share through the Internet is causing a great deal of privacy concerns. These concerns may discourage individuals from revealing their sensitive information. Existing data collection techniques have serious downsides in terms of both efficiency and the levels of protection they offer against various realizations of threats. Moreover, they do not provide any flexibility to the users to be able to specify acceptable levels of privacy protection before deciding whether to participate in the surveys. In this paper, we propose a two-pronged privacy protection model corresponding to these two privacy concerns: these are a new efficient anonymity preserving data collection technique and a method to incorporate heterogeneous privacy constraints. Together, they help preserve the privacy of respondents both during and after data collection.
Riemann Problem Resolution and Godunov Scheme for the Aw-Rascle-Zhang Model
Authors: Mammar Salim , Lebacque Jean-Patrick , Salem Habib Haj
Published: October 2009

Recently, Aw and Rascle and Zhang introduced a new second-order macroscopic model, following the theoretical investigations on the Payne-Whitham second-order modelling by Daganzo. The conserved variables in this model are the density and the relative flow. The aim of this paper is to solve the Riemann problem for the Aw-Rascle-Zhang (ARZ) model for all possible initial conditions, using an extended fundamental diagram. The resolution of the Riemann problem provides the user of the model with a set of nontrivial analytical solutions; it is also a prerequisite for the construction of numerical solution schemes. Some examples are given in which analytical solutions of the Riemann problem are discussed and compared to numerical solutions. The ARZ model shows better fit to real data than the embedded Lighthill-Whitham-Richards (LWR) model for the same set of physical parameters.
Computing Time-Dependent Bid Prices in Network Revenue Management Problems
Authors: Kunnumkal Sumit , Topaloglu Huseyin
Published: October 2009

We propose a new method to compute bid prices in network revenue management problems. The novel aspect of our method is that it naturally provides dynamic bid prices that depend on how much time is left until departure. We show that our method provides an upper bound on the optimal total expected revenue and that this upper bound is tighter than the one provided by the widely known deterministic linear programming approach. Furthermore, it is possible to use the bid prices computed by our method as a starting point in a dynamic programming decomposition-like idea to decompose the network revenue management problem by the flight legs and to obtain dynamic and capacity-dependent bid prices. Our computational experiments indicate that the proposed method improves on many standard benchmarks.
The effectiveness of routinely delivered cognitive behavioural therapy for obsessive‐compulsive disorder: A benchmarking study
Authors: Houghton Simon. , Saxon Dave. , Bradburn Mike. , Ricketts Tom. , Hardy Gillian.
Published: October 2009

Objectives. There is often difficulty in generalizing the results of randomized controlled trials (RCTs) to routine clinical practice given the rigid design features of such studies. The purpose of this study is to describe the effectiveness of routinely delivered, formulation‐based cognitive behavioural therapy (CBT) within a publicly funded clinic for adults with obsessive‐compulsive disorder (OCD) and offer a comparison against the outcomes achieved in efficacy studies for the same population.

Method. Practice‐based prospective study. Routine data collected from a National Health Service out‐patient clinic for adult clients with OCD is benchmarked against the findings of RCTs. The comparison RCTs were identified using a systematic review methodology.

Results. The mean (95% confidence interval) change in Yale–Brown Obsessive Compulsive Scale score pre‐ to post‐therapy in the Sheffield clinic was 10.2 (7.1 – 13.3), which compares well with changes of 11.4 (10.5 – 12.2) for exposure and response prevention trials, 12.9 (11.2 – 14.7) for cognitive therapy trials, and 10.6 (8.5 – 12.8) for CBT trials. The Sheffield results fell within the benchmarks derived from the included RCTs.

Conclusion. These results indicate that CBT for adults with OCD delivered outside the constraints of a clinical trial is equivalently effective but that this conclusion should be tested further on a larger group of patients.
Does time reduce resistance to out‐group critics? An investigation of the persistence of the intergroup sensitivity effect over time
Authors: Hiew Danika N. , Hornsey Matthew J.
Published: October 2009

Group‐directed criticism typically arouses greater defensiveness when it stems from an out‐group member as opposed to an in‐group member (the intergroup sensitivity effect). In light of work on the sleeper effect, the current research examines whether this defensiveness persists over time. Students received criticism of their faculty area from either a member of the same faculty area (in‐group condition), or a member of a different faculty area (out‐group condition), or they received no criticism (control condition). Despite relatively poor recall of the content of the criticism, the intergroup sensitivity effect (ISE) found immediately after presentation of the criticism had not significantly decreased 3–4 weeks later. However, the heightened intergroup bias found immediately after the out‐group criticism did dissipate with time. Implications of these results for those who wish to initiate social change as outsiders are discussed.
Crossover and stability of victim type in child molesters
Authors: Sim Daphne J. , Proeve Michael
Published: October 2009

Purpose. This study examined the degree to which child sex offenders demonstrated crossover in victim choice, as defined by age, gender, and relationship to the offender. It also aimed to explore the direction of the shift in victim type with repeated offending within each of the three domains and to identify variables predictive of crossover behaviour.

Method. The sample comprised 128 adult male child sexual offenders. All had offended against multiple victims and were attending a community‐based assessment and treatment service for sexual offenders at the time of data collection. Variables were gathered, coded, and de‐identified from a manual search through clinical casenotes, from client assessment reports as well as from supplementary information consisting of sentencing remarks or other professional reports.

Results. More than half of the sample (63.3%, N = 81) demonstrated crossover in victim type across at least one domain. Crossover was 48.0% (N = 59) in the age domain, 22.0% (N = 28) in the gender domain, and 25.8% (N = 33) in the relationship to victim domain. Crossover offending was associated with number of victims but unrelated to frequency of offending or to recidivism risk as assessed by a standard risk assessment instrument. Transitional matrices showed general stability in victim type across offences within the gender and relationship domains, but lower stability within the age domain.

Conclusions. Crossover offending behaviour was found to be frequent in the age domain, but the high frequency of crossover in this domain may be artifactual. Crossover offending was less frequent in the gender and relationship domains, but should be taken into account in risk assessment. Victim type shows stability across multiple offences in the gender and relationship to victim domains. Analysis of victim type across multiple offences should be replicated under conditions where disclosure of offending is maximized.
Preliminary Proficiency Testing Results for Succinylacetone in Dried Blood Spots for Newborn Screening for Tyrosinemia Type I
Authors: Adam Barbara W , Lim Timothy H , Hall Elizabeth M , Hannon W Harry
Published: October 2009

Background: Succinylacetone (SUAC) is the primary metabolite accumulated in tyrosinemia type I—an inborn error of metabolism that, if untreated, can cause death from liver failure during the first months of life. Newborn screening laboratories measure SUAC in dried blood spot (DBS) samples to detect asymptomatic tyrosinemia type I. We used panels of SUAC-enriched DBSs to compare and evaluate the performance of these screening tests.

Methods: We prepared sets of DBS materials enriched with predetermined SUAC concentrations and distributed samples of these materials, along with a screening practices questionnaire, to laboratories that perform SUAC tests. We compared their reported SUAC concentrations and questionnaire responses to identify screening practices that affect SUAC test outcomes.

Results: Data from 2 pilot surveys showed large differences among laboratories in SUAC recoveries, reproducible within-laboratory recoveries, and stable performance of the DBS materials. Results from 257 proficiency test analyses contained a total of 6 false-negative misclassifications. Reported recoveries of added SUAC ranged from 0 to >200%. Low-biased SUAC recoveries were associated with 1 method used by 5 laboratories. All laboratories that reported SUAC recoveries ≥100% used DBS matrix calibrators.

Conclusions: The wide ranges of SUAC concentrations reported for pilot and proficiency testing specimens demonstrate a need to harmonize quantitative results among laboratories. Although DBS matrix calibrators are important for optimizing SUAC recoveries, the preparation of these calibrators is not standardized among laboratories. Certified DBS-based SUAC calibrators are needed for accuracy and harmonization.
Hydrogen Embrittlement Test Methods: Current Status and Projections
Authors: Raymond Louis
Published: October 2009

This paper reviews the current standardized test methods for controlling the possibility of hydrogen embrittlement in high-strength steels as a result of different manufacturing and processing variables such as the use of maintenance chemicals or plating processes. The standards are addressed from the point of view of: (1) basic concepts for acceptance; (2) type of loading; (3) significance of time-to-failure and magnitude of stress; (4) future trends, which include the use of fracture mechanics concepts and methods for small-specimen, accelerated testing. Finally, newly proposed standards and new areas requiring hydrogen embrittlement controls are identified.
Electrochemical Aspects of Hydrogen in Metals
Authors: DeLuccia John J.
Published: October 2009

This is a review of the electrode kinetics of the hydrogen evolution reaction and the entry of electrolytic hydrogen into metals as it affects hydrogen embrittlement. Basic electrochemical parameters (for example, exchange current density, activation and concentration polarization, and coverage) are described for the determination of a rate and mechanism for the hydrogen evolution reaction. Hydrogen coverage dependence on overpotential and current is discussed with reference to the Langmuir adsorption isotherm. Reactions responsible for the electrolytic production of hydrogen in aqueous solutions are described for corrosion processes that occur in occluded regions on or below the surface of the metal. Hydrogen adsorption-absorption processes and electrochemical hydrogen permeation test techniques for the determination of the susceptibility of metals to internal hydrogen embrittlement are presented.
Other ASTM Committees and ISO Committees Involved in Hydrogen Embrittlement Test Methods
Authors: Grobin Allen W.
Published: October 2009

Current standards documentation, concerned with the testing or prevention of hydrogen embrittlement, under development by other ASTM committees and by International Standards Organization (ISO) committees is briefly described.
The Barnacle Electrode Method to Determine Diffusible Hydrogen in Steels
Authors: Berman David A. , Agarwala Vinod S.
Published: October 2009

An electrochemical method to determine diffusible hydrogen in steels is described. It is a simple but very sensitive device which is capable of measuring hydrogen concentrations of less than 1 weight ppm. The method makes use of nickel/nickel oxide as a polarizing electrode, which is coupled to a hydrogen-containing steel part. The hydrogen is oxidized at the specimen surface, and the current measured is related to the hydrogen concentration. The method demonstrates a high precision in the measurements. It is shown that the measured hydrogen concentration resulting from cadmium plating is a function of specimen bulk. Results from experiments with plated/baked/stressed 300M steel are reviewed.
The Development of an In-Situ Sensor for Measuring the Hydrogen Content of Liquid Iron
Authors: Ohtsubo Takashi , Kawase Hirahisa , Yamazaki Shu-ichi
Published: October 2009

For in-situ measurement of the hydrogen content of liquid iron, a new inert gas probe technique has been developed which consists of injection of inert gas into molten iron through a nozzle, collection of the ascending bubbles in which hydrogen partial pressure is in equilibrium with the iron, instantaneous determination of hydrogen concentration in the gas using a mass spectrometer, and conversion of the concentration to hydrogen content in iron by Sievert's law. The experimental result is in good agreement with the theoretically calculated hydrogen content. Response is quite rapid (̃ 1.5 min). The efficiency of hydrogen recovery by a bubble is affected by the bubble size, the hydrogen concentration, and the ascending distance. The bubble size is determined by the flow rate and the nozzle size.
A Study of the Effect of Voids on Hydrogen Diffusion Through Electroslag Refined Steel
Authors: Wang Mingmei , Shewmon Paul G.
Published: October 2009

Disk-shaped thin specimens made of electroslag refined (ESR) carbon steel were treated with hydrogen at 758 kPa (450 psi) at 600°C for 120, 240, or 432 h to produce microvoids (from methane bubbles) with a diameter of about 0.1 γm and a volume fraction up to 0.2%. Using the two-step replica technique, the size and density of voids were measured. The hydrogen diffusion coefficients of these specimens were determined by an electrochemical permeation method. Different charging current densities were used. The microvoids serve as traps for hydrogen as indicated by the hydrogen diffusion coefficient decreasing as the current density and the void density increased.
The Present Status of the Disk Pressure Test for Hydrogen Embrittlement
Authors: Fidelle Jean-Pierre
Published: October 2009

This paper is an update of an enormous amount of work done since STP 543. Accept/reject criteria are illustrated as well as numerous parameters examined such as: (1) strain rate, (2) interfacial and geometrical factors, (3) metallurgical factors, and prior embrittlement from other sources or combined mechanisms, for example, gaseous hydrogen embrittlement on previously embrittled titanium or steel.

Applications to sustained load, rising load, cyclic loads and small alternating loads on sustained loads are illustrated.

A large amount of new test results on a variety of material is presented, including welded Inconel 718.
Ranking Materials for Extreme Sour Gas Service Using the Slow Strain Rate Method
Authors: Mclntyre Dale R.
Published: October 2009

Equipment for use in sour gas wells is exposed to high-chloride brines saturated with hydrogen sulfide (H2S) and carbon dioxide (CO2) at temperatures up to 260°C (500°F). Both hydrogen-induced cracking and stress corrosion cracking are possible. However, traditional methods for testing environmental cracking resistance, such as the National Association of Corrosion Engineers (NACE) tension test or the magnesium chloride (MgCl2) test, have limited applicability to this service. The slow strain rate method overcomes many of the disadvantages of more traditional test methods, while posing some unique questions of its own. Apparatus and procedure are described. The theoretical interaction between slowly rising dynamic strain and hydrogen-related cracking is discussed. Selection of appropriate strain rate and sample size will be described. The possible evaluation criteria will be compared, including: time to failure, percent reduction in area, loss of ductile fracture surface area, and the appearance of secondary cracking. Certain ambiguous features in the transition zones between cracking and noncracking environments will be described. The strengths of the method (rapidity, positive results) will be balanced and compared with its limits of use.
Selection of Petroleum Industry Materials Through Use of Environmental Cracking Tests
Authors: Ciaraldi Stephen W.
Published: October 2009

Four environmental cracking problems experienced by the petroleum industry are described. These problems warrant the use of laboratory environmental cracking tests as an aid to materials selection. Test methods used at the Amoco Research Center include tensile-type (static load and slow strain rate), U-bend, bent-beam, and fracture mechanics techniques. Choice of method is shown to depend upon service conditions, alloy system, and product form. Typical test results for carbon and low-alloy steels, stainless steels, and nickel-base alloys are presented. In particular, methods of utilizing test results to provide specific materials selections are described.
In Situ Measurement of Hydrogen in Weld Heat Affected Zones Thru Mass Spectrometry and Computer Analysis
Authors: Pressouyre Gerard M. , Lemoine Veronique , Dubois Daniel J. M. , Leblond Jean-Baptiste , Saillard Patrick R. , Faure Francois M.
Published: October 2009

This paper proposes a new mass spectrometry technique to measure hydrogen evolution in the heat affected zone (HAZ) of a welded material while welding. Square block specimens are used, with a small-diameter hole drilled parallel to the surface to be overlaid at such a depth that the hole will be seated in the future HAZ. This hole is connected to a mass spectrometer that will detect hydrogen evolution in the HAZ during welding; also recorded are the evolutions of temperature in the HAZ and bead deposit advance. Parallel to such experiments, hydrogen diffusion and solubility characteristics have been determined versus temperature using mass spectrometry on base metal and HAZ microstructures.

Results show that hydrogen evolves in the HAZ during welding with characteristic humps and maxima, which may be attributed to variations in diffusion coefficients with temperature and phase changes in the HAZ. These observations were confirmed by computer modelling. Thus, this technique, together with the numerical simulation, is powerful in qualitatively and/or quantitatively evaluating various welding parameters such as: nature of the welding material, the welding process, preheating, and postheating.
Testing of Welding Electrodes for Diffusible Hydrogen and Coating Moisture
Authors: Siewert Thomas A.
Published: October 2009

For the last 35 years the American welding industry has placed limits on electrode coating moisture to control the hydrogen content of shielded metal arc (SMA) welds in order to minimize weld cracking in steels. Within the past several years, however, various tests have been proposed or developed for the direct measurement of diffusible hydrogen in welds. This report compares many of these tests with each other and with the coating moisture test.

The methods of measuring diffusible hydrogen that were compared were the International Institute of Welding (IIW) test (collection over mercury), the American Bureau of Shipping test (collection over glycerin), collection over silicone oil, a gas chromatographic technique, and several variations of the above. The gas chromatographic technique produced results that agreed within 15% with the IIW method, while the other test methods produced results that were often 50% smaller than the IIW value. The lower values were attributed to solubility of hydrogen in the collection media. It was therefore concluded that these two methods also produced the most reliable measure of the diffusible hydrogen content. The coating moisture was measured in the electrodes used and had a poor correlation with the diffusible hydrogen content.
The Effect of Weld Metal Diffusible Hydrogen on the Cracking Susceptibility of HY-80 Steel
Authors: Wong Richard J.
Published: October 2009

An investigation was conducted to characterize the influence of welding variables, such as weld metal diffusible hydrogen content, on the hydrogen cracking resistance of HY-80 steel. The moisture pickup characteristics of several shielded metal-arc welding products were measured by the standard combustion technique. The weld metal diffusible hydrogen level corresponding to the electrode coating moisture was measured by gas chromatography.

Implant weldability tests were performed to quantify the cracking resistance of HY-80 steel under different combinations of weld metal diffusible hydrogen level and welding preheat/inter-pass temperature. Implant lower critical stress values were found to increase with a decrease in weld metal diffusible hydrogen content.

Self-restrained weldability tests (rigidly restrained cracking specimens) were performed at selected conditions determined on the basis of implant testing. The dimensions of rigidly restrained cracking specimens were varied between different tests in order to produce restraint levels that would result in cracking or no cracking situations based on implant lower critical stress values. The results of rigidly restrained cracking tests at reduced preheat temperatures (that is, 0° and 16°C) agreed with anticipated critical stress levels required for cracking as determined by implant lower critical stress values.
Hydrogen Embrittlement and Relief Treatment Study of Zinc Phosphate-Coated Submunitions
Authors: Voorhis Gerard P.
Published: October 2009

The effect of various zinc phosphating treatments on the hydrogen embrittlement susceptibility of high-strength steel artillery submunitions and the effect of subsequent thermal relief treatments were evaluated in this study.

The submunitions were two types of grenade bodies fabricated from AISI 4140 steel and AISI 15B41 steel. The first type of grenade body contained an embossed inside wall and was heat treated to a hardness Rockwell “C” (HRC) range of 38 to 45 HRC. The second type of grenade body contained a smooth inside wall and was heat treated to a hardness range of 44 to 50 HRC.

Test specimens, machined from the heat treated and zinc phosphate-coated components, were in the form of rings that were stressed to 65% of the nominal breaking load for 200 h. Specimens that failed the 200-h test were considered embrittled; specimens that did not fail were considered nonembrittled. Failed specimens were examined with a scanning electron microscope for the evidence of intergranular fracture, which substantiated that hydrogen embrittlement had occurred.

It was shown that the zinc-phosphated material was susceptible to hydrogen embrittlement. The susceptibility increased when the exposure time and the acid concentration of the zinc phosphate process increased. Thermal bake-out treatments at ambient and at elevated temperatures were effective in reducing the embrittlement effect. Thirty days at ambient temperature or 3 h at 93°C (200°F) were found to be adequate in eliminating hydrogen embrittlement. These relief treatments are not effective when the acid concentrations in the zinc phosphate-coating process are abnormally high.
Quantitative Analysis of Critical Concentrations for Hydrogen-Induced Cracking
Authors: Pressouyre Gerard M. , Faure Frangois M.
Published: October 2009

The purpose of this paper is to show how to evaluate the sensitivity of a given material to hydrogen-induced cracking through the use of a conventional electrochemical permeation technique. Prior to the cracking test itself, the permeation cell is used to compute the diffusion, solubility, and trapping characteristics of the material under study; then, hydrogen cracks are created in the disk-shaped specimen and the critical value at which damage appears is found from computed concentration profiles. Because of the numerous underlying theoretical assumptions for the calculation of critical concentrations, the obtained results are finally compared to data gathered from more conventional techniques (chemical analysis, mechanical testing). Critical concentration data for various materials and the use of this data to assess hydrogen embrittlement sensitivity are also discussed.
The Hydrogen Embrittlement Susceptibility of Ferrous Alloys: The Influence of Strain on Hydrogen Entry and Transport
Authors: Scully John R. , Moran Patrick J.
Published: October 2009

The influence of strain and strain rate on hydrogen entry, transport, and trapping in high-strength ferrous alloys and the subsequent effects on hydrogen embrittlement are being investigated in this research program. Most hydrogen permeation measurements reported in the literature presume surface absorption kinetics to be sufficiently fast as to not influence observed changes in the permeation flux. It is interesting that hydrogen recombination poisons (enhancing absorption) are frequently used to observe permeation currents. It is also interesting that environmental slow-strain-rate plastic loading and cyclic loading at low frequency, possibly enhancing either absorption or bulk diffusion of hydrogen, have been observed to increase tendencies towards hydrogen embrittlement. In the present investigation a series of slow-strain-rate measurements, electrochemical measurements to investigate adsorption-absorption kinetics and eventually a combination of these, are being performed and will be described. A discussion of electrochemical techniques being utilized for adsorption-absorption studies is included. It is anticipated that once this program is completed, the influence of plastic deformation on the hydrogen absorption and apparent hydrogen diffusion rate for a high-strength steel will be assessed. Once the effects of surface absorption and bulk diffusion are differentiated, the influence of each will be correlated with the degree of hydrogen-stimulated environmental damage observed for AISI 4340 steel in chloride environments.
Effect of FSH on testicular morphology and spermatogenesis in gonadotrophin-deficient hypogonadal mice lacking androgen receptors
Authors: O'Shaughnessy P J , Monteiro A , Verhoeven G , De Gendt K , Abel M H
Published: October 2009

FSH and androgen act to stimulate and maintain spermatogenesis. FSH acts directly on the Sertoli cells to stimulate germ cell number and acts indirectly to increase androgen production by the Leydig cells. In order to differentiate between the direct effects of FSH on spermatogenesis and those mediated indirectly through androgen action, we have crossed hypogonadal (hpg) mice, which lack gonadotrophins, with mice lacking androgen receptors (AR) either ubiquitously (ARKO) or specifically on the Sertoli cells (SCARKO). Thesehpg.ARKO andhpg.SCARKO mice were treated with recombinant FSH for 7 days and testicular morphology and cell numbers were assessed. In untreatedhpgandhpg.SCARKO mice, germ cell development was limited and did not progress beyond the pachytene stage. Inhpg.ARKO mice, testes were smaller with fewer Sertoli cells and germ cells compared tohpgmice. Treatment with FSH had no effect on Sertoli cell number but significantly increased germ cell numbers in all groups. Inhpgmice, FSH increased the numbers of spermatogonia and spermatocytes, and induced round spermatid formation. Inhpg.SCARKO andhpg.ARKO mice, in contrast, only spermatogonial and spermatocyte numbers were increased with no formation of spermatids. Leydig cell numbers were increased by FSH inhpgandhpg.SCARKO mice but not inhpg.ARKO mice. Results show that in rodents 1) FSH acts to stimulate spermatogenesis through an increase in spermatogonial number and subsequent entry of these cells into meiosis, 2) FSH has no direct effect on the completion of meiosis and 3) FSH effects on Leydig cell number are mediated through interstitial ARs.
Population Density and Instream Habitat Suitability of the Endangered Cape Fear Shiner
Authors: Hewitt Amanda H. , Kwak Thomas J. , Cope W. Gregory , Pollock Kenneth H.
Published: October 2009

The Cape Fear shinerNotropis mekistocholasis an endangered minnow endemic to the Cape Fear River basin of North Carolina; only five populations remain, all of which are declining. Determining the population densities and habitat requirements of the species is critical to its survival and restoration planning. We conducted population surveys (four sites) and instream microhabitat suitability analyses (six sites) on the Rocky and Deep rivers to (1) estimate the population density of Cape Fear shiners, (2) quantify the use, availability, and suitability of microhabitats, and (3) determine whether physical habitat alterations were a likely cause of local extirpations and whether instream habitat limits the occurrence and density of this species. Density ranged from 795 fish/ha to 1,393 fish/ha (4,768–7,392 fish/km) at three of the sites surveyed and was too low to be estimated at the fourth site. The fish most frequently occupied riffles and velocity breaks at moderate depths over gravel substrates. It occupied microhabitats nonrandomly with respect to availability; the microhabitats occupied were similar between spawning and postspawning seasons but shallower during spawning. Comparisons of suitable habitat among sites where the fish is extant, rare, or extirpated suggest that suitable substrate (gravel) is lacking where the fish is rare and that suitable microhabitat combinations, especially with respect to water velocity, are rare at all sites. Potential reintroduction sites where the species is rare or extirpated were shallower than extant sites, and one site where the fish is extirpated contained suitable physical habitat but lacked adequate water quality. Another site where the species is rare would require substrate alteration to improve conditions. The survival and recovery of the Cape Fear shiner is dependent on the protection of remaining suitable physical habitat with approaches that consider instream habitat, water quality, and biotic interactions as well as human uses and alterations of the river, riparian zone, and watershed.
Quantifying Predation on Galaxiids and Other Native Organisms by Introduced Rainbow Trout in an Ultraoligotrophic Lake in Northern Patagonia, Argentina: A Bioenergetics Modeling Approach
Authors: Vigliano Pablo H. , Beauchamp David A. , Milano Daniela , Macchi Patricio J. , Alonso Marcelo F. , Asorey Martín I. García , Denegri María A. , Ciancio Javier E. , Lippolt Gustavo , Rechencq Magali , Barriga Juan P.
Published: October 2009

Exotic rainbow trout Oncorhynchus mykiss support an economically valuable recreational fishery in Patagonia but also create concern for impacts on native organisms. These concerns are intensified by the possibility of hatchery release programs in this region. We estimated losses of different prey from predation by rainbow trout in Lake Moreno, Río Negro Province, Argentina, using a bioenergetics model combined with input data from directed sampling on growth, seasonal diet, distribution, and thermal experience. The fish community was sampled seasonally using gill nets, hydroacoustics, and ichthyoplankton nets. Pelagic galaxiid larvae and benthic juvenile and adult small puyen Galaxias maculatus were the most important components of the diet. Bioenergetics simulations showed that over a 6‐year life span in the lake (ages 1–7), rainbow trout attained a body mass of 2.3 kg and consumed 74.7 kg of food, of which 20% consisted of galaxiid larvae and 16% consisted of adult small puyen. Based on an estimated abundance of 29,000 rainbow trout of ages 1–7, this predator exerted significant but sustainable mortality on the native prey populations, consuming 44 metric tons or an estimated 23% of the annual larval galaxiid production and 35 metric tons of adult small puyen, which represented an unknown fraction of the postlarval population. Galaxiids supported the estimated predation demand under current conditions. However, simulations of stocking strategies normally proposed for this region showed that consumption demands on prey would increase to unsustainable levels, reducing native fish populations and likely reducing growth of rainbow trout. It is also probable that the fish community composition would shift further in response to the increased demand for prey by stocked predators. This implies that in some cases, stocking could jeopardize sport fisheries; stocking strategies should be evaluated on a case‐by‐case basis to be consistent with specific objectives for native fish conservation and sustainable food web interactions.
Spawning Site Selection and Potential Implications of Modified Flow Regimes on Viability of Gulf Sturgeon Populations
Authors: Flowers H. Jared , Pine W. E. , Dutterer A. C. , Johnson K. G. , Ziewitz J. W. , Allen M. S. , Parauka Frank M.
Published: October 2009

Rapid human population growth and an associated increase in consumptive water demands within the ecologically diverse Apalachicola–Chattahoochee–Flint (ACF) River basin of the southeastern United States have led to a series of highly publicized water wars, exacerbated by recent drought conditions, between the states of Alabama, Georgia, and Florida. A key issue is how managing riverine flows to meet human water needs will affect the viability of species that are federally listed as threatened or endangered, including the Gulf of Mexico sturgeon Acipenser oxyrinchus desotoi. Our present understanding of Gulf sturgeon ecology within the Apalachicola River basin indicates that altered riverine flow regimes may affect spawning success and possibly the recruitment patterns of the population. Through intensive field work, we documented Gulf sturgeon spawning site selection in the Apalachicola River and then evaluated the relationship between river stage and the available spawning habitat at these sites. We then used an age‐structured simulation model to assess the effects of changes in recruitment patterns on population viability using hypothetical scenarios based on changes in flow regime and its effect on available spawning habitat. Over 3 years we were able to collect almost 500 Gulf sturgeon eggs in the Apalachicola River at three different spawning sites. We observed that the depths and flows where eggs were found were similar across years and sites despite varying river conditions. River discharges of less than 142 m3/s at Jim Woodruff Lock and Dam significantly reduced the spawning habitat available to Gulf sturgeon at all known spawning sites, potentially affecting recruitment. Gulf sturgeon populations are probably sensitive to changes in recruitment, and if extreme low‐flow events occur with increasing frequency owing to water management policy choices or climatic events, population recovery could be impaired and the risk of extirpation could increase. Managers should consider the potential effects on Gulf sturgeon recruitment when determining future flow regime policies within the ACF.