bluuebunny/crossref_metadata_2025 huggingface dataset:
An Exposure‐Response Threshold for Lung Diseases and Lung Cancer Caused by Crystalline Silica
Authors: Cox, Jr. Louis Anthony (Tony)
Published: April 2011

Whether crystalline silica (CS) exposure increases risk of lung cancer in humans without silicosis, and, if so, whether the exposure‐response relation has a threshold, have been much debated. Epidemiological evidence is ambiguous and conflicting. Experimental data show that high levels of CS cause lung cancer in rats, although not in other species, including mice, guinea pigs, or hamsters; but the relevance of such animal data to humans has been uncertain. This article applies recent insights into the toxicology of lung diseases caused by poorly soluble particles (PSPs), and by CS in particular, to model the exposure‐response relation between CS and risk of lung pathologies such as chronic inflammation, silicosis, fibrosis, and lung cancer. An inflammatory mode of action is described, having substantial empirical support, in which exposure increases alveolar macrophages and neutrophils in the alveolar epithelium, leading to increased reactive oxygen species (ROS) and nitrogen species (RNS), pro‐inflammatory mediators such as TNF‐alpha, and eventual damage to lung tissue and epithelial hyperplasia, resulting in fibrosis and increased lung cancer risk among silicotics. This mode of action involves several positive feedback loops. Exposures that increase the gain factors around such loops can create a disease state with elevated levels of ROS, TNF‐alpha, TGF‐beta, alveolar macrophages, and neutrophils. This mechanism implies a “tipping point” threshold for the exposure‐response relation. Applying this new model to epidemiological data, we conclude that current permissible exposure levels, on the order of 0.1 mg/m3, are probably below the threshold for triggering lung diseases in humans.
No change in hemoglobin mass after 40 days of physical activity in previously untrained adults
Authors: Eastwood A. , Bourdon P. C. , Norton K. I. , Lewis N. R. , Snowden K. R , Gore C. J.
Published: April 2011

A high hemoglobin mass (Hbmass) is associated with a high maximum aerobic power (VO2max), however, the extent to which Hbmass is influenced by training is currently unclear. Accordingly, this study monitored changes in Hbmass and VO2max in 12 previously untrained adults (aged 18–25 years) following 40 days of regular physical activity. Hbmass and VO2max were assessed at the start and end of a 40‐day physical activity program, which comprised of approximately 40 min of daily, moderate‐intensity physical activity. Relative VO2max increased by 11.3%, yet there was no significant change in relative Hbmass (1.7%) and body mass (0.2%) during the 40‐day period. There was a significant correlation between Hbmass and VO2max at the start of the study (r=0.58, P=0.05), but not between the change in relative VO2max and the change in relative Hbmass (r=−0.07, P=0.83). Our results support the concept of relative stability in Hbmass with approximately 1 month of moderate‐intensity physical activity suggesting that Hbmass may be used for talent identification and possibly for anti‐doping purposes.
Early Hardness of Self‐Adhesive Resin Cements Cured under Indirect Resin Composite Restorations
Authors: GIRÁLDEZ ISABEL , CEBALLOS LAURA , GARRIDO MIGUEL A. , RODRÍGUEZ JESÚS
Published: April 2011

Purpose:  To determine the influence of curing mode on the surface hardness of seven resin cements used to lute indirect composite restorations.

Materials and Methods:  Seven commercial dual‐curing resin cements were tested: two were total‐etch (RelyX ARC [3M ESPE, St. Paul, MN, USA] and Variolink II [Ivoclar Vivadent, Schaan, Liechtenstein]); one was self‐etch (Multilink Automix [Ivoclar Vivadent]), and four were self‐adhesive (RelyX Unicem [3M ESPE], Maxcem Elite [Kerr Corp., Orange, CA, USA], SmartCem2 [Dentsply, Detrey, GmbH, Konstanz, Germany], and G‐Cem [GC CORPORATION, Itabashi‐Ku, Tokyo, Japan]). Three specimens (0.5 × 6.5mm) of each material were prepared for each of three experimental groups: Group 1 (cements allowed to self cure); Group 2 (cements light‐cured for 40 seconds); and Group 3 (cements light‐cured for 80 seconds). All specimens were cured through a 4‐mm‐thick composite cylinder (Filtek Z250‐A3). Surface microhardness numbers were determined at 20 min after preparation. Results were analyzed by two‐way analysis of variance and Student–Newman–Keuls tests (p < 0.05).

Results:  Superficial hardness was significantly influenced by the resin cement tested (p < 0.0001), the curing mode (p < 0.0001), and their interaction (p < 0.0001). RelyX ARC exhibited the highest mean microhardness values regardless of the curing mode. Light‐curing significantly increased the microhardness of all resin cements studied, and these values increased even further with a doubling of irradiation time. Self‐adhesive cements exhibited different behavior according to the curing mode. RelyX Unicem was highly sensitive to light irradiation, showing the lowest mean values in the self‐curing mode. After light irradiation for 40 or 80 seconds, Maxcem Elite exhibited the lowest mean hardness values of all the resin cements tested.

Conclusion:  The microhardness of resin cements is highly dependent on the brand. Dual‐curing resin cements should always be light irradiated for longer periods than that recommended by manufacturers.

CLINICAL SIGNIFICANCE

Dual‐curing resin cements should always be light‐cured for longer irradiation times, as light irradiation for 80 seconds yields the highest microhardness values in comparison with self‐curing or light irradiation for 40 seconds. However, some self‐adhesive resin cements exhibit low microhardness values when used to cement 4‐mm‐thick indirect composite restorations regardless of the curing mode applied.

(J Esthet Restor Dent 23:116–125, 2011)
Fair‐ranking properties of a core selection and the Shapley value
Authors: Chun Youngsub , Park Boram
Published: April 2011

The fair‐ranking principle states that if all the underlying outside data of some coalition are the same in two games, then the relative positions of the players in the coalition should be the same in the two games. We investigate the implications of the principle in the context of transferable utility games. Our first axiom, coalitional fair‐ranking, requires that if the worth of a given coalition changes while the worths of other coalitions remain fixed, then the relative positions of all players in the given coalition should not be affected. We show that for games with at least three players, there is no core selection satisfying coalitional fair‐ranking. If the change is limited to the worth of the grand coalition, then there is a core selection satisfying the requirement. In addition, we present a new axiomatic characterization of the Shapley value on the basis of strong coalitional fair‐ranking: it requires that if a game is added to another game with two symmetric players, then the relative positions of the symmetric players should not be affected. The Shapley value is the only value satisfying strong coalitional fair‐ranking together with efficiency, the null player property and strategic equivalence.
When is an antitrust authority not aggressive enough in fighting cartels?
Authors: Harrington, Jr Joseph E.
Published: April 2011

If an antitrust authority chooses an enforcement policy to maximize the number of successfully prosecuted cartels, when does that policy minimize the number of cartels that form? When the detection and prosecution of cartels is inherently difficult, it is found that an antitrust authority’s policy minimizes the number of cartels, as is socially desirable. However, when the detection and prosecution of cartels is not too difficult, an antitrust authority is not aggressive enough in that it prosecutes too few cartel cases.
Functional Cortical and Subcortical Abnormalities in Pedophilia: A Combined Study Using a Choice Reaction Time Task and fMRI
Authors: Poeppl Timm B. , Nitschke Joachim , Dombert Beate , Santtila Pekka , Greenlee Mark W. , Osterheider Michael , Mokros Andreas
Published: April 2011

Introduction

Pedophiles show sexual interest in prepubescent children but not in adults. Research into the neurofunctional mechanisms of paraphilias has gathered momentum over the last years.

Aim

To elucidate the underlying neural processing of sexual interest among pedophiles and to highlight the differences in comparison with nonparaphilic sexual interest in adults.

Methods

Nine pedophilic patients and 11 nonpedophilic control subjects underwent functional magnetic resonance imaging (fMRI) while viewing pictures of nude (prepubescents, pubescents, and adults) and neutral content, as well as performing a concomitant choice reaction time task (CRTT).

Main Outcome Measures

Brain blood oxygen level-dependent (BOLD) signals and response latencies in the CRTT during exposure to each picture category.

Results

Analysis of behavioral data showed group differences in reaction times regarding prepubescent and adult but not pubescent stimuli. During stimulation with pictures displaying nude prepubescents, pedophiles showed increased BOLD response in brain areas known to be involved in processing of visual sexual stimuli. Comparison of pedophilic patients with the control group discovered differences in BOLD responses with respect to prepubescent and adult but not to pubescent stimuli. Differential effects in particular occurred in the cingulate gyrus and insular region.

Conclusions

The brain response of pedophiles to visual sexual stimulation by images of nude prepubescents is comparable with previously described neural patterns of sexual processing in nonpedophilic human males evoked by visual stimuli depicting nude adults. Nevertheless, group differences found in the cingulate gyrus and the insular region suggest an important role of these brain areas in pedophilic sexual interest. Furthermore, combining attention-based methods like CRTT with fMRI may be a viable option for future diagnostic procedures regarding pedophilia.
Ultrastructural and Quantitative Study of Clitoral Cavernous Tissue from Living Subjects
Authors: Caruso Salvatore , Cianci Antonio , Malandrino Chiara , Cavallari Lidia , Gambadoro Orazio , Arena Grazia , Pispisa Letterio , Agnello Carmela , Romano Mattea , Cavallari Vittorio
Published: April 2011

Introduction

There has never been an investigation about the in vivo clitoral structure.

Aim

To study the “in vivo” age-related structural changes of the clitoris in healthy women and in those affected by metabolic disorders.

Methods

Forty-three women subgrouping in (i) five teenagers, aged 14–18; (ii) eight young premenopausal women, aged 23–32; (iii) 10 premenopausal women, aged 38–47; (iv) nine diabetic premenopausal women, aged 27–43; and (v) 11 naturally postmenopausal women aged 51–55. Each woman underwent microbiopsy of the clitoral body by means of an 18G needle, length 100 mm, using a semiautomatic gun during total anesthesia for a benign gynecological pathology. The tissue removed was processed for electron microscopy. A morphometric procedure was used on electron micrographs.

Main Outcome Measure

Micro ultrastructure observation of clitoral tissue.

Results

The cavernous tissue from the teenagers and young women showed large amounts of smooth muscle cells (SMCs). The intercellular connective tissue showed scanty, small isometric collagen fibers and amorphous extracellular matrix. In the premenopausal diabetic women, ultrastructural abnormalities of SMCs were observed, consisting of increase of glycogen deposits, infolding cell borders, and cytoplasmic vacuoles. Moreover, the intercellular connective tissue was increased by densely packed collagen fibers. Finally, in the healthy, natural postmenopausal women, the SMCs were moderately reduced in number. We observed age-related structural changes of the vascular spaces and of the vascular lacunae. The SMC mean thickness was reduced with age; vascular abnormalities appeared to be correlated with the presence of metabolic diseases, such as diabetes.

Conclusion

Our “in vivo” study could help to understand some aspects of the physiology of the clitoris and its role in sexual response. Apart from data obtained by studying healthy women and women affected by diabetes, other investigations are needed to study subgroups of otherwise healthy sexually dysfunctional women.
Painful Love—“Hispareunia” After Sling Erosion of the Female Partner
Authors: Mohr Stefan , Kuhn Peter , Mueller Michael D. , Kuhn Annette
Published: April 2011

Introduction

Sling erosion/extrusion is a complication after suburethral sling insertion for female stress urinary incontinence that occurs in approximately 6% of patients. Symptoms may include vaginal discharge, infections, postcoital bleeding, and alterations of the sexual function. Little is known about the effect of sling erosion on the sexual function of the male partner.

Aim

The aim of this study was to determine male sexual function in partners of women who had undergone sling insertion for stress urinary incontinence and who developed sling erosion postoperatively.

Main Outcome Measures

Main outcome measures were the Brief Male Sexual Function Inventory (BMSFI) and visual analog scale (VAS) scores.

Methods

Male partners of patients who presented with sling erosion for various reasons were addressed and asked to fill in the BMSFI and assess sexual pain using the VAS before and 6 months after the sling erosion of their female partners was treated. Participants gave informed consent and those who had undergone prostate surgery during the past 12 months were excluded. For statistical analyses, SPSS version 10.0 (SPSS Inc., Chicago, IL, USA) was used.

Results

Thirty-two males were included in the study and produced a full set of data. VAS scores as a measurement for “hispareunia” improved from a median score of 8 before to a median score of 1 after intervention. Some domains of male sexual function (sexual interest, sexual drive, ejaculation, and erection) were significantly improved whereas the strength of erection, problems with ejaculation, and problems with lack of interest were not statistically significantly changed.

Conclusions

Changes of male sexual function and particularly pain after sling insertion in their female partners may be due to sling exposure. Sexual interest and drive may be negatively influenced. Male dyspareunia is a complaint that can be treated effectively by correcting the sling exposure.
The Ability of the General Male Public to Assess Their Suitability to Take 50-mg Sildenafil: An Assessment of the Comprehension of Patient Information Materials via Internet Survey
Authors: Symonds Tara , Coyne Karin S. , Margolis Mary Kay , Schnetzler Gabriel
Published: April 2011

Introduction

Erectile dysfunction (ED) is the most common male sexual dysfunction and has a negative impact on masculinity and self-esteem. Phosphodiesterase type 5 inhibitors, including sildenafil, are the first-line treatment option for ED. Providing appropriate information regarding suitability for using sildenafil is important.

Aim

The purpose of this study was to assess whether a broad spectrum of men could appropriately evaluate their suitability for 50-mg sildenafil after reviewing patient information materials.

Main Outcome Measures

Patient information (Pack) on appropriate use of 50-mg sildenafil and patient information leaflet (PIL), a Web survey including demographics, self-assessed suitability for sildenafil use, and suitability screener.

Methods

A randomly selected, population-representative Web-based panel of males in the UK was recruited for this study. Eligible men answered a brief sociodemographic questionnaire and then were presented with the Pack. If a participant desired additional information, he could also review the PIL. The participants then rated the Pack and PIL (if reviewed), self-assessed their suitability for sildenafil use, and completed a previously validated screener for suitability.

Results

A total of 1,275 men aged 40 and above were included in these analyses; the mean age was 57.8 ± 9.9 years. A total of 1,054 men reported ED; 517 men (40.5%) deemed themselves suitable for sildenafil; 504 men (39.6%) deemed themselves unsuitable; and 254 (19.9%) were unsure. The concordance rate between screener-assessed suitability and self-assessed suitability was 70.9% (95% confidence interval [CI] = 68.1–73.7%). When accounting for men who would not take sildenafil even though they were suitable or would seek additional information from a healthcare professional prior to using sildenafil, the concordance rate was 84.2% (95% CI = 82.2–86.2%).

Conclusion

The results of this study suggest that men in the general population are capable of using written sildenafil patient education materials to accurately assess their suitability for treatment with 50-mg sildenafil.
Localized HI 21-cm absorption towards a double-lobed z= 0.24 radio galaxy
Authors: Curran S. J. , Whiting M. T. , Webb J. K. , Athreya R.
Published: April 2011

We present the results of a mini-survey for associated HI 21-cm absorption at z≤ 0.42 with the Giant Metrewave Radio Telescope. Our targets are radio galaxies, selected on the basis that the γ ≈ 1216 Å luminosities are below LUV∼ 1023 W Hz-1, above which there has never been a detection of 21-cm absorption. Of the three sources for which we obtained good data, two are unclassified active galactic nuclei (AGNs) and one is type-2. Being a non-detection, the type-2 object is consistent with our previous result that 21-cm absorption in radio sources is not dictated by unified schemes of AGN. In the case of the detection, the absorption only occurs towards one of the two resolved radio lobes in PKS 1649-062. If the absorption is due to another intervening galaxy, or cool HI gas in the intergalactic medium, covering only the south-west (SW) lobe, then, being at the same redshift, this is likely to be gravitationally bound to the optical object identified as PKS 1649-062. If the absorption is due to an inclined disc centred between the lobes, intervening the SW lobe while being located behind the north-east (NE) lobe, by assuming that it covers the emission peak at ≈150 kpc from the nucleus, we estimate a dynamical mass of ≈3 × 1012 M⊙ for the disc.
Astaxanthin Preparation by Lipase‐Catalyzed Hydrolysis of Its Esters from Haematococcus pluvialis Algal Extracts
Authors: Zhao Yingying , Guan Feifei , Wang Guili , Miao Lili , Ding Jing , Guan Guohua , Li Ying , Hui Bodi
Published: April 2011

Abstract:  Five of 8 fungal lipases screened were found to effectively hydrolyze astaxanthin esters from Haematococcus pluvialis algal cell extracts. Among these, an alkaline lipase from Penicillium cyclopium, expressed in Pichia pastoris, had the highest enzymolysis efficiency. Tween80 was shown to be an effective emulsifier in this lipase hydrolysis system for the 1st time. A series of experiments were performed to find optimal conditions for hydrolysis (pH, temperature, reaction time, lipase dosage). In the optimal reaction system, Tween80 and H. pluvialis extracts (mass ratio 1:1) were emulsified and added to the above lipase at a dosage of 4.6 U/μg (relative to total carotenoids), in phosphate buffer (0.1 M, pH 7.0), and incubated at 28 °C for 7 h, with agitation at 180 rpm. The free astaxanthin recovery ratio under these conditions was 63.2%.

Practical Application:  The chemical hydrolysis of astaxanthin esters from both H. pluvialis and Adonis rarely produced astaxanthin but always astacene and was therefore not considered applicable for industrial use. We would expect that our effort in this study was able to make a contribution to construct a new procedure apart from chemical methods.
Transient Pressure Loss in Compressor Station Piping Systems
Authors: Brun Klaus , Nored Marybeth , Tweten Dennis , Kurz Rainer
Published: April 2011

“Dynamic pressure loss” is often used to describe the added loss associated with the time varying components of an unsteady flow through a piping system in centrifugal and reciprocating compressor stations. Conventionally, dynamic pressure losses are determined by assuming a periodically pulsating 1D flow profile and calculating the transient pipe friction losses by multiplying a friction factor by the average flow dynamic pressure component. In reality, the dynamic pressure loss is more complex and is not a single component but consists of several different physical effects, which are affected by the piping arrangement, structural supports, piping diameter, and the level of unsteadiness in the flow stream. The pressure losses due to fluid-structure interactions represent one of these physical loss mechanisms and are presently the most misrepresented loss term. The dynamic pressure losses, dominated at times by the fluid-structure interactions, have not been previously quantified for transient flows in compressor piping systems. A number of experiments were performed by Southwest Research Institute (SwRI) utilizing an instrumented piping system in a compressor closed-loop facility to determine this loss component. Steady and dynamic pressure transducers and on-pipe accelerometers were utilized to study the dynamic pressure loss. This paper describes the findings from reciprocating compressor experiments and the various fluid modeling studies undertaken for the same piping system. The objective of the research was to quantitatively assess the individual pressure loss components, which contribute to dynamic pressure (nonsteady) loss based on their physical basis as described by the momentum equation. Results from these experiments were compared with steady-state and dynamic pressure loss predictions from 1D and 3D fluid models (utilizing both steady and transient flow conditions to quantify the associated loss terms). Comparisons between the fluid model predictions and experiments revealed that pressure losses associated with the piping fluid-structure interactions can be significant and may be unaccounted for by advanced 3D fluid models. These fluid-to-structure losses should not be ignored when predicting dynamic pressure loss. The results also indicated the ability of an advanced 1D Navier–Stokes solution at predicting inertial momentum losses. Correspondingly, the three-dimensional fluid models were able to capture boundary layer losses affected by 3D geometries.
The Design of an Ambient Neutron Dose-Equivalent Meter
Authors: Wenming Xia , Mingchun Jia , Zhirong Guo
Published: April 2011

At present, most of the developed neutron dosimeters used to measure the neutron ambient dose-equivalent that has a moderator with a single counter, applied in neutron radiation fields within large range energies from thermal to MeV neutrons, are not a satisfaction to energy response. The purpose of this article is to design a suitable neutron dosimeter for radiation protection purpose. In order to overcome the disadvantage of the energy response of the neutron dosimeters combining a single sphere with a single counter, three spheres and three H3e counters were combined for the detector design. The response function of moderators with different thicknesses combined with SP9 H3e counters were calculated with Monte Carlo code MCNP 4C. The selection of three different thicknesses of the moderating polyethylene sphere was done with a MATLAB program. A suitable combination of three different thicknesses was confirmed for the detector design. The electronic system of the neutron dosimeter was introduced. The results of ambient dose-equivalent per unit fluence in different radiation areas were calculated, analyzed, and compared with the values recommended in the ISO standard. The calculated result explains that it is very significant to this design of neutron dosimeter; it may be applied to the monitor of the ambient dose in the neutron radiation fields, improving at present the status of the energy response of neutron dosimeters.
Trajectory Tracking via Independent Solutions to the Geometric and Temporal Tracking Subproblems
Authors: Ambike Satyajit , Schmiedeler James P. , Stanišić Michael M.
Published: April 2011

Trajectory tracking is accomplished by obtaining separate solutions to the geometric path-tracking problem and the temporal tracking problem. A methodology enabling the geometric tracking of a desired planar or spatial path to any order with a nonredundant manipulator is developed. In contrast to previous work, the equations are developed using one of the manipulator’s joint variables as the independent parameter in a fixed global frame rather than a configuration-dependent canonical frame. Both these features provide significant practical advantages. Furthermore, a strategy for determining joint velocities and accelerations at singular configurations is provided, which allows the manipulator to approach and/or move out of a singular configuration with finite joint velocities without sacrificing the geometric fidelity of tracking. An example shows a spatial six-revolute robot tracking a trajectory using the developed method in conjunction with resolved-acceleration feedback control.
Hydrodynamic Analysis of a Horizontal Axis Marine Current Turbine With a Boundary Element Method
Authors: Baltazar J. , Falcão de Campos J. A. C.
Published: April 2011

A low order potential based panel code is used to analyze the flow around the blades of a horizontal axis marine current turbine. An empirical vortex model is assumed for the turbine wake, which includes the variation of pitch of the helicoidal vortices trailing behind the blades. The analysis is carried out for uniform inflow conditions in steady flow for a turbine with controllable pitch for two different pitch settings in a wide range of tip-speed-ratios. Grid convergence studies carried out to verify the accuracy of predicted pressure distributions and integrated forces show a fast convergence with grid refinement for this geometry. The effect of the helicoidal wake model parameters used in the analysis is found to have a strong influence in the performance curves. The results are compared with experimental data from literature and with the lifting line theory. A discussion of viscous effects is also provided to help explaining the main discrepancies with the data.
Natural Convection in a Rocking Square Enclosure: Experimental Results
Authors: Chávez R. , Solorio F. J. , Cervantes J. G.
Published: April 2011

Experimental results for the natural convection in a rocking enclosure are presented. A square closed cavity heated from below and cooled from above periodically turns around of its horizontal symmetry central line. The oscillation amplitude was from −15 deg to 15 deg, and four time periods were employed (30 min, 60 min, 90 min, and 120 min) for three established Rayleigh numbers (3×104, 6×104, and 1×105). High purity glycerin was used as the working fluid, and particle image velocimetry (PIV) was employed to obtain the velocity fields. The obtained flow patterns have a strong dependence on the Rayleigh number.
Bejan’s Constructal Theory Analysis of Gas-Liquid Cooled Finned Modules
Authors: Lorenzini Giulio , Moretti Simone
Published: April 2011

High performance heat exchangers represent nowadays the key of success to go on with the trend of miniaturizing electronic components as requested by the industry. This numerical study, based on Bejan’s Constructal theory, analyzes the thermal behavior of heat removing fin modules, comparing their performances when operating with different types of fluids. In particular, the simulations involve air and water (as representative of gases and liquids), to understand the actual benefits of employing a less heat conductive fluid involving smaller pressure losses or vice versa. The analysis parameters typical of a Constructal description (such as conductance or Overall Performance Coefficient) show that significantly improved performances may be achieved when using water, even if an unavoidable increase in pressure losses affects the liquid-refrigerated case. Considering the overall performance: if the parameter called Relevance tends to 0, air prevails; if it tends to 1, water prevails; if its value is about 0.5, water prevails in most of the case studies.
Distribution of Vapor Inside a Cylindrical Minichannel With Evaporative Walls and Its Effect on Droplet Growth by Heterogeneous Nucleation
Authors: Anand Sushant , Lee Jae Yong , Veettil Deepak , Son Sang Young , Jog Milind A.
Published: April 2011

The present study aims to understand the dynamics of particle growth inside a minichannel where evaporation from heated wet wall column generates supersaturated conditions. Such multiphase flow with phase-change is encountered in condensation particle sensors where nanoscale particles grow to micrometer size and can be measured optically. To develop condensation particle sensors that are miniscale and highly portable, we have computationally modeled the flow, heat, and mass transfer in a minichannel and determined parameters that facilitate particle growth. The mass, momentum, energy, and species conservation equations are solved, and particles are tracked and their growth through condensation is determined. Variation of thermophysical properties as a function of temperature and species concentration is incorporated for accurate determination of particle growth. The results show that the size of condensation sensors can be decreased by employing minichannels where conditions can be created, which enhance supersaturation region inside the channel where condensation occurs on the nanoparticles by heterogeneous nucleation and cause them to grow to micron sizes. The effects of inlet humidity, inlet temperature, inlet flow rate, and wall temperature on the operation of the miniscale sensor are investigated. The numerical framework provides solution to optimal working of the sensor.
Modeling Hydraulic Conductivity and Swelling Pressure of Several Kinds of Bentonites Affected by Salinity of Water
Authors: Tanaka Yukihisa , Hasegawa Takuma , Nakamura Kunihiko
Published: April 2011

In case of construction of repository for radioactive waste near the coastal area, the effect of salinity of water on hydraulic conductivity as well as swelling pressure of bentonite as an engineered barrier should be considered because it is known that the hydraulic conductivity of bentonite increases and swelling pressure decreases with increasing salinity of water. Though the effect of salinity of water on hydraulic conductivity and swelling pressure of bentonite has been investigated experimentally, it is necessary to elucidate and to model the mechanism of the phenomenon because various kinds of bentonites may possibly be placed in various salinities of ground water. Thus, in this study, a model for evaluating hydraulic conductivity as well as swelling pressure of compacted bentonite is proposed considering the effect of salinity of water as follows: a) Change in number of flakes of a stack of montmorillonite because of cohesion. b) Change in viscosity of water in interlayer between flakes of montmorillonite. Quantitative evaluation method for hydraulic conductivity and swelling characteristics of several kinds of bentonites under saline water is proposed based on the model mentioned above.
Planning of Large-Scale In-Situ Gas Generation Experiment in Korean Radioactive Waste Repository
Authors: Kim Juyoul , Kim Sukhoon , Park Jin Beak , Lee Sunjoung
Published: April 2011

In the Korean LILW (Low- and Intermediate-Level radioactive Waste) repository at Gyeongju city, the degradation of organic wastes and the corrosion of metallic wastes and steel containers would be important processes that affect repository geochemistry, speciation and transport of radionuclides during the lifetime of a radioactive waste disposal facility. Gas is generated in association with these processes and has the potential threat to pressurize the repository, which can promote the transport of groundwater and gas, and consequently radionuclide transport. Microbial activity plays an important role in organic degradation, corrosion and gas generation through the mediation of reduction-oxidation reactions. The Korean research project on gas generation is being performed by Korea Radioactive Waste Management Corporation (hereafter referred to as “KRMC”). A full-scale in-situ experiment will form a central part of the project, where gas generation in real radioactive low-level maintenance waste from nuclear power plants will be done as an in-depth study during ten years at least. In order to examine gas generation issues from an LILW repository which is being constructed and will be completed by the end of December, 2012, two large-scale facilities for the gas generation experiment will be established, each equipped with a concrete container carrying on 16 drums of 200 L and 9 drums of 320 L of LILW from Korean nuclear power plants. Each container will be enclosed within a gas-tight and acid-proof steel tank. The experiment facility will be fully filled with ground water that provides representative geochemical conditions and microbial inoculation in the near field of repository. In the experiment, the design includes long-term monitoring and analyses for the rate and composition of gas generated, and aqueous geochemistry and microbe populations present at various locations through on-line analyzers and manual periodical sampling. A main schedule for establishing the experiment facility is as follows: Completion of the detailed design until the second quarter of the year 2010; Completion of the manufacture and on-site installation until the second quarter of the year 2011; Start of the operation and monitoring from the third quarter of the year 2011.
Structural Intergrity Evaluation Approach for PWR Spent Nuclear Fuel
Authors: Nam Y. S. , Kim Y. H. , Jeon K. L. , Lee S. K. , Choi K. S. , Cho C. S.
Published: April 2011

PWR fuel assembly (FA) experiences many changes from the time it is manufactured, loaded in the reactor and removed from the reactor for reprocessing or stroage etc. Any of these alterations which impact spent nuclear fuel (SNF) integrity should be considered to design a cask/canister. Regarding the cask/canister design, there could be a freedom to design a system that mitigates the forces transmitted to SNF and fuel rods. If the cask/canister design prevents or mitigates forces transmitted to its contents such that structural integrity is not significantly compromised, the detailed SNF properties are necessary to make a decision of the elaborated design parameters. An approach to those work formations is to analyze mechanical characteristics of structural components. Those informations are also used to evaluate hypothetical accident, to select limiting FA for cask/canister to accommodate various kinds of SNFs and to design transportation/storage system for SNFs. Especially, FA structural properties are a sort of essential data. Thus, in this paper, some approaches to evaluate SNF mechanical characteristics are suggested through the existing technical information review, some test data and the analysis methodology, and also closely study the mechanical characteristics of a representative SNF for its general comprehension.
A Structural Reliability Approach to Management of Defective Spiral Welding in a ‘Legacy’ Pipeline
Authors: Gardiner Michael , Michie Ross , Douce Gerardo
Published: April 2011

Metrogas SA operates a natural gas distribution concession within the Greater Buenos Aires region of Argentina. In August 2007 a failure occurred on a section of the 22-bar system that dates from the early 1960s and, as such, was ‘inherited’ by Metrogas at privatization. The line pipe in this part of the system is spirally welded and at the failure point the spiral weld root was found to have been incomplete. Subsequent investigations showed that incomplete spiral welds were also present at other locations in the same section of the system. This paper describes some of the steps taken to investigate the incident of 2007 and to manage the threat from other defective spiral welds in the same pipeline section. We present a limit state model for through-wall failure of such features and show how this was used to help understand the incident. We also discuss modeling of uncertainties in parameters of the model and look at results from a probabilistic structural reliability implementation of the limit state function, which allowed the failure frequency of other defective spiral welds in this section to be predicted for various reductions of the operating pressure. Metrogas was then able to use these quantified reliability data to make a responsible, informed decision to keep the affected section in downrated service.
Robotic Inspection of Unpiggable Natural Gas Transmission and Distribution Pipeline
Authors: Laursen Paul , D’Zurko Daphne , Vradis George , Swiech Craig
Published: April 2011

The present paper presents the development effort and pre-commercial deployment of Explorer II — a semi-autonomous, self-powered, tetherless robotic platform, carrying a Remote Field Eddy Current (RFEC) sensor, for the inspection of unpiggable natural gas transmission and distribution pipelines in the 6 to 8 inch (152 to 203 mm) range, including those that feature multiple diameters, short radius and mitered bends, and tees. The system is based on a modular design that allows the system to be deployed in various configurations to carry out visual inspection and/or non-destructive evaluation (NDE) of a pipeline. The heart of this system is a RFEC sensor able to measure the pipeline’s wall thickness. In addition, two fisheye cameras at each end of the robot provide high quality visual inspection capabilities for locating joints, tee-offs, and other pipeline features. The system can operate, including launching and retrieval, in live pipelines with pressures up to 750 psig (50 bars). The system is currently being offered for pre-commercial deployments and is expected to be commercially available in the Fall of 2010.
A New ILI Tool for Metal Loss Inspection of Gas Pipelines Using a Combination of Ultrasound, Eddy Current and MFL
Authors: Willems Herbert , Jaskolla Beate , Sickinger Thorsten , Barbian Alfred , Niese Frank
Published: April 2011

The two prevailing technologies in in-line inspection (ILI) of pipelines used for metal loss detection are magnetic flux leakage (MFL) and ultrasonic testing (UT). The ultrasonic method provides a more precise depth sizing as a direct measurement of the remaining thickness of the pipe wall is obtained. The advantage of providing more precise defect data leads, in turn, to a more accurate and reliable defect assessment thus reducing follow-up costs for the pipeline operator. As conventional ultrasonic tools, which are based on piezoelectric transducers, require a liquid coupling medium to couple the ultrasonic energy into the pipe wall, this technology is readily applicable to the majority of liquids pipelines, but not to gas pipelines (unless a batch of liquid is used). In order to apply ultrasonic ILI technology for metal loss inspection to gas pipelines directly, a new tool was developed based on the EMAT (electro-magnetic acoustic transducer) principle by which ultrasound is generated in the surface of the pipe wall through electromagnetic interaction. EMAT sensors utilize coils for sending and receiving ultrasound. Since coils can also be used to pick up MFL signals and eddy current signals, the sensors were designed such that, apart from the ultrasonic signals, these additional signals are recorded simultaneously. The availability of three simultaneous, independent measurements allows for considerable improvement with regard to both defect sizing and feature discrimination. In the paper, the new sensor concept and the setup of the ILI tool are described. First results are presented and discussed.
Effects of Cathodic Protection on Cracking of High-Strength Pipeline Steels
Authors: Elboujdaini M. , Revie R. W. , Attard M.
Published: April 2011

A comparison was made between four strength levels of pipeline steels (X-70, X80, X-100 and the X-120) from the point of view of their susceptibility to hydrogen embrittlement under cathodic protection. The main aim was to determine whether the development of higher strength materials led to greater susceptibility to hydrogen embrittlement. This was achieved by straining at 2×10−6 s−1 after cathodic charging in a simulated dilute groundwater solution (NS4) containing 5% CO2/95% N2 (pH approximately 6.7). The results showed quantitatively the loss of ductility after charging, and the loss of ductility increases with strength level of the steel. All four steels exhibited a loss of ductility at overprotected charging potential and an increasing amount of brittleness on the fracture surface. Ductility in solution was measured under four different levels of cathodic protection, ranging from no cathodic protection to 500 mV of overprotection with respect to the usually accepted criterion of −850 mV vs. Cu/CuSO4 reference electrode. Experiments were carried out by straining during cathodic polarization in a simulated dilute ground water solution (NS-4 solution). Strain rates used were 2×10−6 s−1. After failure, the fracture surfaces were characterized by examination using scanning electron microscopy (SEM). Under cathodic protection, all four steels showed loss of ductility and features of brittle fracture. The loss of ductility under cathodic polarization was larger the greater the strength of the steel and the more active (i.e., more negative) the applied potential. The Ductility Reduction Index (DRI) was defined to quantify the reduction in ductility.
A New Model for Dynamic Crack Propagation and Arrest in Gas Pipelines
Authors: Misawa Kei , Imai Yasuhito , Aihara Shuji
Published: April 2011

A new model of unstable ductile crack propagation and arrest of pressurized gas pipeline is presented. The model couples pipe deformation and fracture with gas decompression. The model also takes account of backfill effect. Pipe deformation and pressure changes are obtained by solving one-dimensional differential equations. Validity of the model was checked by comparing with published full-scale burst test data. The model can predict history of crack velocity and arrest crack length with fairly good accuracy. The model can be applied to wide ranges of gases, pipe grades and pipe sizes because it does not rely on parameter adjustment by experimental data sets but is based on physical assumptions.
Effective Pipeline Integrity Management in the Magallanes Region of Chile
Authors: Salinas E. , Mun˜oz A. , Wilde A. , Healy J. , Bakayeva M.
Published: April 2011

Empresa Nacional del Petro´leo (ENAP) is an energy company, wholly owned by the Chilean Government. With regards to overall management, the company comprises of two Business Divisions: Exploration and Production (Up-stream) and Refining and Logistic (Down-stream), complemented by corporate managerial structures. The objective of ENAP’s Exploration and Production (UpStream) business line is the exploration and exploitation of hydrocarbons (oil and natural gas) in the South of Chile (Magallanes) and abroad, as well as geo-thermal energy, in this case, associated with private entities in areas of Northern Chile. Within the Magallanes region ENAP operates approximately 2,200 km of natural gas, crude oil and refined product pipelines. These pipelines range in diameter from 4 to 20 inch and the majority of pipelines are over 30 years old. Due to operational reliability reasons, since 1998 ENAP has been regularly inspecting its pipelines using intelligent in-line inspection tools. Furthermore, since 2006, as part of an overall pipeline integrity management plan ENAP has been conducting Fitness for Service assessments on selected pipelines including a risk-based assessment considering pipeline condition and the impact on the continuity of operation. The Integrity Management Plan implemented by ENAP in the Magallanes region has been applied to all pipelines transporting gas, crude oil and refined products, including those built after 1990. This plan comprises the construction phase, from which invaluable information is gathered for later use. The primary aims of ENAP’s integrity management plan are: - To protect the public; - To protect the surrounding environment by preventing pipeline failures; - To ensure efficient usage of the budget available to conduct maintenance tasks; - To prevent damage to the pipelines, e.g. due to corrosion activity; - To provide clarity of activities being performed by ENAP in order to ensure an efficient, safe and reliable pipeline system. This paper provides a description of the integrity management strategy adopted by ENAP and includes a review of a number of the challenges encountered during its implementation.
Numerical Investigation of Oblique Pipeline/Soil Interaction in Sand
Authors: Daiyan Nasser , Kenny Shawn , Phillips Ryan , Popescu Radu
Published: April 2011

Energy pipelines pass through various environmental and geotechnical conditions. They are usually buried and can be subjected to geohazards like landslides, fault movements or large subsidence resulting in large permanent ground deformations along part of their length. The effect of large permanent ground deformations on buried pipelines can be critical for their integrity and safety. Understanding this effect is important for pipeline designers. In the current engineering guidelines the pipeline/soil interaction has been idealized using structural modeling which evaluates the soil behavior using discrete springs with load-displacement relationships provided in three perpendicular directions (longitudinal, lateral horizontal and vertical). These springs are usually independent and during a 3D pipe/soil relative displacement they can not account for cross effects due to shear interaction between different soil zones along the pipe. Some studies in the past including an experimental study by the authors have shown the importance of cross effects between axial and lateral soil restraints on the pipeline during oblique axial/lateral pipeline/soil relative movements. In this numerical study a three-dimensional continuum finite element model is developed using ABAQUS/Standard software. The model has been calibrated against the centrifuge tests conducted by the authors. The numerical model successfully reproduces the ultimate loads and also the shape of failure surfaces observed during physical tests. The numerical model will be used to extend the physical investigation results by parametric studies in future works.
Strain Measurement in Composite Materials Using Microstrip Patch Antennas
Authors: Daliri Ali , John Sabu , Galehdar Amir , Rowe Wayne S. T. , Ghorbani Kamran
Published: April 2011

In this paper the feasibility of using a circular microstrip patch antenna to detect strain in composite plates and the effects of different materials on sensitivity of the patch antenna are investigated. Also the effect of strain direction on the frequency shift is studied. The theoretical model shows a linear relationship between strain and the shift in the resonant frequency of the antenna in any material. A circular microstrip patch antenna is designed and fabricated to work at 1.5GHz and attached to three different materials for testing. Both Finite Element Analysis (FEA) and experimental tests have been undertaken to corroborate the relationship between strain and frequency shift. The ultimate intention of this work is to configure antennas for the detection of relatively small damage zones in structures and to do so wirelessly.