bluuebunny/crossref_metadata_2025 huggingface dataset:
Micromachined Methanol Reformer for Portable PEM Fuel Cells
Authors: Kim Taegyu , Lee Dae Hoon , Park Dae-Eun , Kwon Sejin
Published: February 2008

Fabrication procedures for a micromethanol reformer including catalyst preparation, coating, and patterning on a wafer are described. Cu-based catalyst was prepared by coprecipitation method. The effects of precipitation conditions on the catalytic activity and adhesion of coated catalyst on the substrate were tested to find the optimum precipitation condition. For coating purposes, the prepared catalyst was ground into powder and mixed with binder in the solvent. Simultaneous precipitation of catalyst and binder on the wafer produced catalyst layer that is uniform and rigidly found to the wafer surface. The amount of coated catalyst on the wafer was 5–8mg∕cm2 with a thickness of 30μm. By repetition of coating procedure, catalyst mass up to 15mg∕cm2 was obtained with increased reactivity. Patterned catalyst layer was obtained by novel lift-off process of polyvinyl alcohol sacrificial layer. A micromethanol reformer was fabricated using a typical lithography procedure including catalyst coating and patterning process. Typical methanol conversion was higher than the conventional packed bed reactor.
Improvement of CO Tolerance of Proton Exchange Membrane Fuel Cell by an Air-Bleeding Technique
Authors: Chen Chiun-Hsun , Chung Chen-Chung , Lin Hsiang-Hui , Yan Yi-Yie
Published: February 2008

This study investigates the improvement of proton exchange membrane fuel cell (PEMFC) carbon monoxide by periodic air dosing. The carbon monoxide in the fuel gas leads to a significant loss in power density due to CO poisoning in the anode. The method involves bleeding air into the anode fuel stream (H2–CO), which contains CO in various concentrations (20ppm, 52.7ppm, and 100ppm). In the transient CO poisoning test, air bleeding is performed for four different periodic air dosing and cell voltage is fixed at 0.6V. The result of a dosing of air for 10s in intervals of 10s is similar to that of continuous air bleeding except for 100ppm CO. The CO tolerance of the fuel cell and cell performance recovery from poisoning can be improved by air bleeding.
Fuel Economy and Emission Performance of Fuel Cell-Based Diesel HEVs
Authors: Crunkleton Daniel , Strattan Robert
Published: February 2008

The fuel economy and emission advantages of diesel-electric hybrid powertrain modifications and an auxiliary fuel cell subsystem over those of a conventional midsize crossover SUV are discussed. The vehicle architecture is representative of one selected for the multiyear ChallengeX intercollegiate student design contest. To analyze the fuel economy, a simple “top-level” approach is used to estimate the fuel economy characteristics and performance potential to illustrate the advantages of the hybrid-electric powertrain configuration and the auxiliary fuel cells. Chained energy efficiency assumptions for the powertrain components lead to gasoline equivalent fuel mileage estimates. In the emission analysis, the greenhouse gases, regulated emissions, and energy use in transportation model is used to track the environmental impact of the powertrain on a well-to-wheels basis.
Macroscopic Modeling of a PEFC System Based on Equivalent Circuits of Fuel and Oxidant Supply
Authors: Chrenko Daniela , Péra Marie-Cécile , Hissel Daniel , Geweke Martin
Published: February 2008

In this paper, a polymer electrolyte fuel cell system is modeled in order to investigate the following operational modes: transient and nominal operations and rejuvenation process. As a preliminary investigation, the Ballard NEXA™ power module performances are experimentally characterized. The power consumptions of ancillaries, such as the air fan, are then evaluated to investigate the system. To achieve an overall system model, components, such as the compressor, the pipes, the valves, the expander, and the humidifier, are then simulated. This simulation is based on the same assumption: Fluidic circuits are described by an electrical analogy. The anodic gas management is finally described according to the delivered output current.
Correlation Between Vibration Excitation Forces and the Dynamic Characteristics of Two-Phase Cross Flow in a Rotated-Triangular Tube Bundle
Authors: Zhang C. , Pettigrew M. J. , Mureithi N. W.
Published: February 2008

Two-phase cross flow exists in many shell-and-tube heat exchangers. Flow-induced vibration excitation forces can cause tube motion that will result in long-term fretting wear or fatigue. Detailed flow and vibration excitation force measurements in tube bundles subjected to two-phase cross flow are required to understand the underlying vibration excitation mechanisms. Some of this work has already been done. The distributions of both void fraction and bubble velocity in rotated-triangular tube bundles were obtained. Somewhat unexpected but significant quasiperiodic forces in both the drag and lift directions were measured. The present work aims at understanding the nature of such unexpected drag and lift quasiperiodic forces. An experimental program was undertaken with a rotated-triangular array of cylinders subjected to air/water flow to simulate two-phase mixtures. Fiber-optic probes were developed to measure local void fraction. Both the dynamic lift and drag forces were measured with a strain gage instrumented cylinder. The investigation showed that the quasiperiodic drag and lift forces are generated by different mechanisms that have not been previously observed. The quasiperiodic drag forces appear related to the momentum flux fluctuations in the main flow path between the cylinders. The quasiperiodic lift forces, on the other hand, are mostly correlated to oscillations in the wake of the cylinders. The quasiperiodic lift forces are related to local void fraction measurements in the unsteady wake area between upstream and downstream cylinders. The quasiperiodic drag forces correlate well with similar measurements in the main flow stream between cylinders.
Experimental and Numerical Techniques in Fluids
Authors: Durst Franz
Published: February 2008

The development of fluid mechanics is briefly reviewed, and the importance of fluid flows to heat and mass transport in nature and also in science and engineering is outlined. The early theoretical developments are explained, and it is indicated that the basic equations were already available at the end of the 18th century. Methods to solve these equations for engineering flows were not, however, developed until the second half of the 20th century. This was an important period for fluid flow research during which all the experimental fluid mechanics methods, particularly the optical methods, available today were also developed. The same is true for all the numerical methods that are used very successfully nowadays to solve scientific and engineering fluid flow problems. The Institute of Fluid Mechanics at the University of Erlangen-Nürnberg has contributed extensively to these developments.
Leak Before Break: Studies in Support of New R6 Guidance on Leak Rate Evaluation
Authors: Taggart J. P. , Budden P. J.
Published: February 2008

The concept of leak-before-break (LBB) is often used in safety cases for pressure systems, particularly, in the nuclear industry. An important factor in making a LBB case is in the prediction of the leak rate of fluid through a crack. This paper presents a summary of a program of work, which had the aim of improving guidance on leak rate evaluation for the LBB procedures in the R6 defect assessment methodology. Methods of calculating leak rates have been reviewed, and this has led to a crack morphology model being proposed, which represents single-phase isothermal compressible flow through a crack. In the crack morphology model, the flow is assumed by default to be fully rough turbulent, and the effective roughness to vary between a local roughness value for narrow cracks and a global value (i.e., the overall crack contours) for wide cracks. The effect of pressure drops due to changes in the flow direction at crack turns has also been included. Calculations using the model show that the friction factor relation due to Spence et al. (1991, “Leakage Flow Through Small Cracks—Report of Second Stage of Experimental Work,” unpublished) gives better agreement with measured flow rates than that due to Button et al. (1978, “Gas Flow Through Cracks,” ASME J. Fluids Eng., 100, pp. 453–458), which tends to overestimate the flow rate for the examples studied. The inclusion of an inertial pressure term arising from changes in overall flow direction appears to be justified.
A New Technique for Intergranular Crack Formation in Alloy 600 Steam Generator Tubing
Authors: Lee Tae Hyun , Hwang Il Soon , Chung Han Sub , Park Jang Yul
Published: February 2008

For the integrity management of steam generator (SG) tubes, nondestructive evaluation performed using eddy current test (ECT) is necessary in the assessment. The reliability of ECT evaluation is dependent on the accuracy of ECT for various kinds of defects. For basic calibration and qualification of these techniques, cracked SG tube specimens having mechanical and microstructural characteristics of intergranular cracks in the field are needed. To produce libraries of laboratory-degraded SG tubes with intergranular cracks, a radial denting method was explored for generating inside diameter and outside diameter axial cracks by three-dimensional finite element analysis and experimental demonstration. The technique is proven to be applicable for generating axial cracks with long and shallow geometries as opposed to the semicircular cracks typically obtained by the internal-pressurization method. In addition, a direct current potential drop method with array probes was developed for accurate monitoring and controlling of crack size and shape. By these methods, long and shallow intergranular axial cracks more typical of actual degraded SG tubes were successfully produced.
Failure Mode and Failure Strengths for Wall Thinning Straight Pipes and Elbows Subjected to Seismic Loading
Authors: Hasegawa Kunio , Miyazaki Katsumasa , Nakamura Izumi
Published: February 2008

It is important to assess the failure strengths for pipes with wall thinning to maintain the integrity of the piping systems and to make codification of allowable wall thinning. Full-scale fracture experiments on cyclic loading under constant internal pressure were performed for 4in. diameter straight pipes and 8in. diameter elbow pipes at ambient temperature. The experiments were low cycle fatigue under displacement controlled conditions. It is shown that a dominant failure mode under cyclic loading for straight pipes and elbows is crack initiation∕growth accompanying swelling by ratchet or buckling with crack initiation. When the thinning depth is deep, the failure mode is burst and crack growth with ratchet swelling. In addition, failure strengths were compared with the design fatigue curve of the ASME Code Sec. III. It is shown that pipes with wall thinning less than 50% of wall thickness have sufficient margins against a seismic event of the safety shutdown earthquake.
Evaluating Plastic Loads in Torispherical Heads Using a New Criterion of Collapse
Authors: Camilleri Duncan , Mackenzie Donald , Hamilton Robert
Published: February 2008

In ASME Design by Analysis, the plastic load of pressure vessels is established using the twice elastic slope criterion of plastic collapse. This is based on a characteristic load-deformation plot obtained by inelastic analysis. This study investigates an alternative plastic criteria based on plastic work dissipation where the ratio of plastic to total work is monitored. Two sample analyses of medium thickness torispherical pressure vessels are presented. Elastic perfectly plastic and strain hardening material models are considered in both small and large deformation analyses. The calculated plastic loads are assessed in comparison with experimental results from the literature.
Integrity of Roller-Expanded Tube-to-Tubesheet Joints With Overenlarged Tubesheet Holes
Authors: Shuaib A. N. , Merah N. , Ahmed M. , Al-Nassar Y. N. , Al-Anizi S. S.
Published: February 2008

This paper presents the results of an experimental investigation conducted to evaluate the effect of initial tube-tubesheet diametral clearance on the integrity of roller-expanded tube-to-tubesheet joints in overenlarged tubesheet holes. The criteria of evaluating joint integrity include the pullout force and hydraulic tightness of the joints in which tubes were expanded to 5% wall reduction after metal to metal contact of the tube with the tubesheet hole. The levels of clearance investigated were selected to cover a range that exceeded by ten times that prescribed by the Tubular Exchangers Manufacturers Association (TEMA) standards (Standards for the Tubular Exchanger Manufacturers Association, 1988, 7th ed., TEMA, Tarrytown, NY). The pullout test results showed that, within the investigated range of clearance, the joint strength has not declined below the strength of joints with clearance levels within the TEMA range. In fact, the pullout force exhibited a slight linear increasing trend with the increase in initial clearance, which is attributed to the effect of tube strain hardening. The hydrotest results indicated that all joints within the investigated clearance levels were hydraulically tight when they were tested at 1.5 times the design pressure of the heat exchanger for a duration of 30min. A relationship between rolling specific energy and initial joint clearance has been developed.
Residual Thermal Stresses Induced by Local Heat Treatment on Spherical Vessels and Their Influential Factors
Authors: Ze-jun Wang , Hong-yang Jing
Published: February 2008

For the purpose of finding a way to control effectively the residual thermal stresses induced by local heat treatment on spherical vessels, a thermal tracing program is developed successfully based on the transient thermal analysis and controlling method of average temperature of nodes located in an “observed region.” Typical calculation cases reveal that the local heat treatment process itself does cause obvious residual thermal stress that is high enough to cause yield when concentrated heating on small region is adopted, but decentralized heating on a larger region can lower effectively the residual thermal stresses to a rather desirable level. It can be found through a one by one analysis of ten factors, which are possibly influential on residual thermal stress: arc radius of heated region, holding temperature, volume, and wall thickness of the vessel are primary effective factors. The bandwidth of the annular insulated region, the heating rate, and the size of the observed region are secondary factors. Heating pattern, holding time, and cooling rate can hardly affect the residual thermal stress. Considering the primary factors except holding temperature, and taking 30% of yield stress as the expected residual thermal stress level, the recommended arc radius of heated region should be 2.2Rt in minimum.
Finite Element Modeling of a Lightweight Composite Blast Containment Vessel
Authors: Trabia Mohamed B. , O’Toole Brendan J. , Thota Jagadeep , Matta Kiran K.
Published: February 2008

This paper presents various approaches for finite element modeling of a cylindrical lightweight composite vessel for blast containment purposes. The vessel has a steel liner that is internally reinforced with throttle and gusset steel plates and wrapped with a basalt fiber∕epoxy composite. The vessel design is fairly complex, including many geometric details and several components with different material models. The objective of this work is to determine an accurate and efficient procedure for modeling this type of vessels. This model can be used within an iterative optimization process. Different modeling approaches using various combinations of element types, material models, and geometric details are explored. Results of these models are compared to available experimental data. Accuracy and computational time between all these models are also compared. A suitable modeling method is recommended based on these findings.
Thermal Protection Provided by Impact Limiters to a Containment Seal Within a Truck Package
Authors: Greiner Miles , Chalasani Narayana Rao , Suo-Anttila Ahti
Published: February 2008

The Container Analysis Fire Environment (CAFE) computer code is used to simulate the response of a generic legal-weight-truck package to 3h fires. Simulations are performed with the package centered 1m above a 7.2‐m-diameter JP-8 fuel pool. They are also performed with the package horizontally offset from that location by 1m and 2.5m. Simulations without impact limiters are performed to quantify the level of thermal protection they provide. The minimum fire duration that causes the seal to reach its temperature of concern is determined for each configuration. When the center of the no-impact limiter package is within 2.5m of the pool center, 0.7h fires are capable of causing the seal to reach its temperature of concern. By contrast, the intact package protects the seal in fires that last more than 2h. These results help risk analysts understand the effect of package position and the role of impact limiters on accident consequences.
Steady-State Creep Analysis of Thick-Walled Spherical Pressure Vessels With Varying Creep Properties
Authors: You L. H. , Ou H.
Published: February 2008

Based on basic equations of steady-state creep of spherically symmetric problems, a simple and efficient iterative method is proposed in this paper to determine creep deformations and stresses in thick-walled spherical vessels with varying creep properties subjected to internal pressure. The convergence of the proposed iterative method and the influences of varying and constant material properties on stresses and equivalent strain rate are discussed. How different material parameters involved in Norton’s law affect radial and circumferential stresses together with the equivalent strain rate in thick-walled spherical vessels under internal pressure is investigated.
High Pressure Steel Storage Vessels Used in Hydrogen Refueling Station
Authors: Zheng Jinyang , Li Lei , Chen Rui , Xu Ping , Kai Fangming
Published: February 2008

The storage of hydrogen in a compressed gaseous form offers the simplest solution in terms of infrastructure requirements and has become the most popular and most highly developed hydrogen storage method. Hydrogen storage vessels are the key equipment of hydrogen refueling stations. Seamless pressure vessels made from high strength steel, which are now used in hydrogen refueling stations, are limited in volume, susceptible to hydrogen embrittlement, and difficult for online safety monitoring. In order to solve the aforementioned problems, the authors have developed a multifunctional steel layered hydrogen storage vessel with a volume of 5m3 and a design pressure of 42MPa for the first demonstration hydrogen refueling station in the People’s Republic of China, which is flexible in design, convenient in fabrication, safe in use, and easy for online safety monitoring.
Prediction of Thermoacoustic Vibration of Burner/Furnace Systems in Utility Boilers
Authors: Eisinger Frantisek L. , Sullivan Robert E.
Published: February 2008

Seven burner/furnace systems, three of which vibrated and four of which did not vibrate in operation are evaluated for thermoacoustic oscillations. The evaluation is based on the Rijke and Sondhauss models representing the combined burner/furnace (cold/hot) thermoacoustic systems. Frequency differences between the lowest vulnerable furnace acoustic frequencies in the burner axial direction and those of the systems’ Rijke and Sondhauss frequencies are evaluated to check for resonances. Most importantly, the stability of the Rijke and Sondhauss models is checked against the published design stability diagram of Eisinger (1999, “Eliminating Thermoacoustic Oscillations in Heat Exchanger and Steam Generator Systems,” ASME J. Pressure Vessel Technol., 121, pp. 444–452) and Eisinger and Sullivan (2002, “Avoiding Thermoacoustic Vibration in Burner/Furnace Systems,” ASME J. Pressure Vessel Technol., 124, pp. 418–424). It is shown that thermoacoustic oscillation can be well predicted by the published design stability diagram with the vibrating cases falling into the unstable zone above the stability line and the nonvibrating cases congregating in the stable zone below the stability line. The evaluation suggests that the primary criterion for predicting thermoacoustic oscillations is the stability of the thermoacoustic system and that frequency differences or resonances appear to play only a secondary role. It is concluded, however, that in conjunction with stability, the primary criterion, sufficient frequency separation shall also be maintained in the design process to preclude resonances. The paper provides sufficient details to aid the designers.
Buckling of Externally Pressurized Prolate Ellipsoidal Domes
Authors: Smith P. , Błachut J.
Published: February 2008

Details are given of a numerical and experimental study into buckling of steel ellipsoidal domes loaded by static external pressure. A range of geometries and thicknesses of domes is examined, as is the influence of different boundary conditions. Shells are examined on the basis of having the same mass. The main focus of the study is on prolate domes, i.e., those taller than a hemisphere of the same base radius. Numerical predictions are confirmed by pressurizing six laboratory scale prolate domes to destruction. Details are given of the manufacture and test procedure for the domes. The adverse effects of variations in shape and wall thickness are discussed, and finite element predictions are made for geometrically imperfect domes. Correlation between the two sets of results is good. Numerically and experimentally obtained results are related to the current design codes: ASME Boiler and Pressure Vessel Code, Sec. 8, Division 2 (described hereon as ASME VIII), PD5500, and ECCS recommendations (ASME B&PV Code, 2004 ed., Sec. 8, Division 2, New York, NY; BSI 2003 “Published Document PD5500: Specification for Unfired Pressure Vessels,” BSI London; European Convention for Constructional Steelwork Recommendations, 1988 “Buckling of Stell Shells-European Recommendations,” ECCS-TWG 8.4, 4th ed., Brussels), which at present make no provision for prolate domes. Suggestions are made for the possible inclusion of such domes into the standards.
Resource Letter DEAU-1: Dark energy and the accelerating universe
Authors: Linder Eric V.
Published: February 2008

This Resource Letter provides a guide to the literature on dark energy and the accelerating universe. It is intended to be of use to researchers, teachers, and students at several levels. Journal articles, books, and websites are cited for the following topics: Einstein’s cosmological constant, quintessence or dynamical scalar fields, modified cosmic gravity, relations to high-energy physics, cosmological probes and observations, terrestrial probes, calculational tools and parameter estimation, teaching strategies and educational resources, and the fate of the universe.
Coherent states for the bouncing pendulum and the paddle ball
Authors: Andrews Mark
Published: February 2008

The coherent states of the simple harmonic oscillator with an impenetrable barrier at its center are studied. This half oscillator is the equivalent of a pendulum that bounces elastically off a vertical wall directly below the point of suspension with the angle of swing sufficiently small. The system can also be considered as a paddle ball, where the paddle is fixed and the ball is constrained by a spring attached to the paddle. The coherent states are almost the same as the familiar Gaussian coherent states of the full oscillator, except when they overlap the barrier. The solutions can be easily extended to two and three dimensions and gravity can be included if the impenetrable barrier is vertical. To better understand the form of the expectation values of the position and momentum, we investigate some general aspects of the effect of impenetrable barriers on the dynamics of wavepackets.
A new method to demonstrate frustrated total internal reflection in the visible band
Authors: You Yizhuang , Wang Xiaohan , Wang Sihui , Pan Yonghua , Zhou Jin
Published: February 2008

We describe a new method to demonstrate frustrated total internal reflection in the visible band using the 100nm thick air film near the center of Newton’s rings. Experimental measurements of the light intensity distribution validate the theoretical predictions.
Cue and ball deflection (or “squirt”) in billiards
Authors: Cross Rod
Published: February 2008

A billiard ball struck by a cue travels in the same direction as the cue unless the ball is struck toward one side in order to impart sidespin. In that case the ball deflects or “squirts” away from the line of approach of the cue, typically by a few degrees. Measurements and calculations are presented showing how a cue tip slides across the ball if it is unchalked, resulting in a large squirt angle, and how it grips the ball when it is chalked, resulting in a smaller squirt angle.
Convenience Voting
Authors: Gronke Paul , Galanes-Rosenbaum Eva , Miller Peter A. , Toffey Daniel
Published: February 2008

Forms of convenience voting—early in-person voting, voting by mail, absentee voting, electronic voting, and voting by fax—have become the mode of choice for >30% of Americans in recent elections. Despite this, and although nearly every state in the United States has adopted at least one form of convenience voting, the academic research on these practices is unequally distributed across important questions. A great deal of literature on turnout is counterbalanced by a dearth of research on campaign effects, election costs, ballot quality, and the risk of fraud. This article introduces the theory of convenience voting, reviews the current literature, and suggests areas for future research.
Large-Scale Evaluation of Genetic Variants in Candidate Genes for Colorectal Cancer Risk in the Nurses' Health Study and the Health Professionals' Follow-up Study
Authors: Hazra Aditi , Chanock Stephen , Giovannucci Edward , Cox David G. , Niu Tianhua , Fuchs Charles , Willett Walter C. , Hunter David J.
Published: February 2008

Advances in genomics offer new strategies for assessing the association of common genetic variations at multiple loci and risk of many diseases, including colorectal cancer. Low-penetrance alleles of genes in many biological pathways, such as DNA repair, metabolism, inflammation, cell cycle, apoptosis, and Wnt signaling, may influence the risk of nonfamilial colorectal cancer. To identify susceptibility genes for colorectal cancer, we designed a large-scale case-control association study nested within the Nurses' Health Study (190 cases and 190 controls) and the Health Professionals' Follow-up Study (168 cases and 168 controls). We used a custom GoldenGate (Illumina) oligonucleotide pool assay including 1,536 single nucleotide polymorphisms (SNP) selected in candidate genes from cancer-related pathways, which have been sequenced and genotyped in the SNP500Cancer project; 1,412 of the 1,536 (92%) of the SNPs were genotyped successfully within 388 genes. SNPs in high linkage disequilibrium (r2 ≥ 0.90) with another assayed SNP were excluded from further analyses. As expected by chance (and not significant compared with a corrected Bonferroni P = 0.00004), in the additive model, 11 of 1,253 (0.9%) SNPs had a Ptrend < 0.01 and 38 of 1,253 (3.0%) SNPs had a Ptrend ≥ 0.01 and Ptrend < 0.05. Of note, the MGMT Lys178Arg (rs2308237) SNP, in linkage disequilibrium with the previously reported MGMT Ile143Val SNP, had an inverse association with colorectal cancer risk (MGMT Lys178Arg: odds ratio, 0.52; 95% confidence interval, 0.35-0.78; unadjusted Ptrend = 0.0003 for the additive model; gene-based test global P = 0.00003). The SNP500Cancer database and the Illumina GoldenGate Assay allowed us to test a larger number of SNPs than previously possible. We identified several SNPs worthy of investigation in larger studies. (Cancer Epidemiol Biomarkers Prev 2008;17(2):311–9)
V89L Polymorphism of the 5α-Reductase Type II Gene (SRD5A2), Endogenous Sex Hormones, and Prostate Cancer Risk
Authors: Boger-Megiddo Inbal , Weiss Noel S. , Barnett Matt J. , Goodman Gary E. , Chen Chu
Published: February 2008

We examined the combined effect of circulating sex hormones and SRD5A2 V89L polymorphism on prostate cancer risk in a case-control study (300 cases and 300 controls) nested within the Carotene and Retinol Efficacy Trial. A moderate increase in risk associated with above-median serum levels of androstenedione and dehydroepiandrosterone sulfate (DHEAS) was present irrespective of V89L genotype. However, in L/L or V/L men, above-median DHEAS levels were associated with an increased risk of aggressive tumors [odds ratios (OR), 3.12; 95% confidence interval (95% CI), 1.28-7.63] but not of nonaggressive ones (OR, 0.56; 95% CI, 0.25-1.25). Above-median serum levels of free estradiol were associated with a lower risk, especially for aggressive cancer. The association with aggressive disease was more pronounced in men with a V/V genotype (OR, 0.34; 95% CI, 0.14-0.81), than in men with an L/L or V/L genotype (OR, 0.77; 95% CI, 0.37-1.60). Above-median levels of 3α-diol G were associated with an increased risk, but only in men with the L/L or V/L genotype (OR, 2.16; 95% CI, 1.31-3.56). The increase in risk in L/L and V/L men was restricted to aggressive tumors. Our study observed that only in men with the L/L or V/L genotype were increased serum levels of DHEAS and 3α-diol G positively associated with a higher risk of aggressive prostate cancer. Free estradiol levels were negatively associated with risk of aggressive prostate cancer in men with the V/V genotype. However, the absence of an overall association between V89L genotype and aggressive prostate cancer argues for a cautious interpretation of these observations. (Cancer Epidemiol Biomarkers Prev 2008;17(2):286–91)
Differential Roles of p16INK4A and p14ARF Genes in Prognosis of Oral Carcinoma
Authors: Sailasree R. , Abhilash A. , Sathyan K.M. , Nalinakumari K.R. , Thomas Shaji , Kannan S.
Published: February 2008

Background: Oral cancer patients are found to have poor clinical outcome and high disease recurrence rate, in spite of an aggressive treatment regimen. The inactivation of INK4A/ARF loci is reported to be second to p53 inactivation in human cancers. The purpose of this study was to assess the prognostic significance of the molecular aberrations in the INK4A locus for effective identification of aggressive oral carcinoma cases needing alternate therapy.

Materials and Methods: The study composed of 116 patients freshly diagnosed with oral carcinoma. The genetic and epigenetic status of the p16INK4A and p14ARF genes was evaluated. The relation between these genic alterations and different treatment end points, such as residual disease (initial response), disease recurrence, and overall survival, along with the standard clinical markers, were analyzed.

Results: 62% of the study cases had p16INK4A gene abnormalities, with deletion accounting for 33% and methylation for 29%. Alterations in p14ARF gene either by deletion (12%) and/or methylation (18%) were observed in 30% of the cases. p16INK4A deletion was associated with aggressive tumors, as evidenced by the nodal involvement of the disease. Low or absence of p16INK4A protein adversely affected the initial treatment response. Promoter methylation of p16INK4A was associated with increased disease recurrence and acts as an independent predictor for worse prognosis. Surprisingly, p14ARF methylation associated with lower recurrence rate in oral cancer patients with a good clinical outcome. Overall survival of these patients was associated with tumor size, nodal disease, and p16INK4A protein expression pattern. Our results indicate that p16INK4A and p14ARF alterations constitute a major molecular abnormality in oral cancer cases.

Conclusion: The molecular profile of INK4A/ARF locus, both at DNA and protein level, could be used as a prognostic biomarker for assessing the aggressiveness of disease in oral carcinoma patients. The study further shows the opposing clinical effect of these two genes, transcribed from the same locus, in oral cancer patients. (Cancer Epidemiol Biomarkers Prev 2008;17(2):414–20)
The Effect of Difluoromethylornithine on Decreasing Prostate Size and Polyamines in Men: Results of a Year-Long Phase IIb Randomized Placebo-Controlled Chemoprevention Trial
Authors: Simoneau Anne R. , Gerner Eugene W. , Nagle Ray , Ziogas Argyrios , Fujikawa-Brooks Sharon , Yerushalmi Hagit , Ahlering Thomas E. , Lieberman Ronald , McLaren Christine E. , Anton-Culver Hoda , Meyskens Frank L.
Published: February 2008

Background: Prostate cancer is a major health issue, and prevention of prostate cancer and/or its progression will yield benefits for men. Difluoromethylornithine (DFMO) is an antiproliferative agent, inhibiting ornithine decarboxylase, the first enzyme in the polyamine pathway, and has been studied as a therapeutic and chemopreventive agent. The prostate has high levels of tissue polyamines and has shown sensitivity to DFMO both in vitro and in vivo.

Methods: Eighty-one men participated in a 1-year randomized trial of placebo or DFMO. Prostate volume determination and biopsy of the prostate for histology and polyamine content were done at baseline and after 12 months. Other biomarker variables were assessed, including total and free prostate-specific antigen and prostate-specific antigen doubling time.

Results: Compared with baseline, men receiving DFMO had a smaller increase in prostate volume (0.14 cm3) than those on placebo (2.95 cm3; P = 0.0301) at 1 year. In addition, DFMO caused a 60.8% reduction of prostate putrescine levels compared with a 139.5% increase in the placebo arm (P = 0.0014). Stratification by ornithine decarboxylase genotype showed that DFMO reduced prostate volume (P = 0.029) and putrescine levels (P = 0.0053) in the AA + GA group but not in the GG group. There were no grade 3 or 4 toxicities. There was no clinical ototoxicity, with one subclinical grade 2 hearing decline on audiogram.

Conclusion: In this randomized placebo-controlled trial, DFMO induced a decrease of prostate putrescine levels and rate of prostate growth. The potential of this compound for prostate cancer or hyperplasia should be further studied. (Cancer Epidemiol Biomarkers Prev 2008;17(2):292–9)
A Common 8q24 Variant and the Risk of Colon Cancer: A Population-Based Case-Control Study
Authors: Li Li , Plummer Sarah J. , Thompson Cheryl L. , Merkulova Alona , Acheson Louise S. , Tucker Thomas C. , Casey Graham
Published: February 2008

Three recent studies identified common variants on 8q24 that confer modestly increased susceptibility to colorectal cancer. Here, we replicate the association in a population-based case-control study of colon cancer, including 561 cases and 721 unrelated controls. The rs6983267 marker was significantly associated with colon cancer risk. Compared with those homozygous for the T allele, the heterozygous and homozygous carriers for the G allele had an age-adjusted odds ratio of 1.39 (95% confidence interval, 1.03-1.88) and 1.68 (95% confidence interval, 1.21-2.33), respectively. An additive model showed strong evidence for a gene-dose response relationship (Ptrend = 0.0022). The association remained statistically significant when restricted to Caucasians only (527 cases and 679 controls; Ptrend = 0.0056). Further adjustment for other known risk factors did not alter the results. Stratified analysis revealed no evidence for effect modification by family history of colorectal cancer, age, or gender. These data replicate the association identified from recent studies, providing additional evidence supporting the rs6983267 genetic polymorphism as a marker predisposing to colon cancer. (Cancer Epidemiol Biomarkers Prev 2008;17(2):339–42)
Exfoliated Cells in Stool: A Source for Reverse Transcription-PCR–Based Analysis of Biomarkers of Gastrointestinal Cancer
Authors: Yu Ying Jie , Majumdar Adhip P.N. , Nechvatal Jordan M. , Ram Jeffrey L. , Basson Marc D. , Heilbrun Lance K. , Kato Ikuko
Published: February 2008

Because the colonic mucosa is in direct contact with digesta, luminal exposure to potentially carcinogenic or chemopreventive agents may be important in colorectal carcinogenesis, independently of the effects of systemic exposure through the circulation. To date, few biomarkers for luminal exposure have been identified, and isolation of reasonably good quality fecal human RNA remains difficult. In this study, we assessed the yield and quality of RNA extracted from 10 human stool samples after storage with several commercially available preservatives compared with stool samples immediately frozen in liquid nitrogen. This study shows that careful design of primer pairs which amplify a short length of DNA is key to obtaining interpretable and reproducible results. Moreover, the use of commercially available RNA preservation kits enables investigators to collect usable fecal samples from large populations. Of all the preservative methods tested, RNAlater had the best performance in terms of overall quality, quantity, and level of genomic DNA contamination, and thus deserves further investigation. (Cancer Epidemiol Biomarkers Prev 2008;17(2):455–8)
Psychosocial Outcomes and Health-Related Quality of Life in Adult Childhood Cancer Survivors: A Report from the Childhood Cancer Survivor Study
Authors: Zeltzer Lonnie K. , Lu Qian , Leisenring Wendy , Tsao Jennie C.I. , Recklitis Christopher , Armstrong Gregory , Mertens Ann C. , Robison Leslie L. , Ness Kirsten K.
Published: February 2008

Purpose: Psychological outcomes, health-related quality of life (HRQOL), and life satisfaction are compared between 7,147 adult childhood cancer survivors and 388 siblings from the Childhood Cancer Survivor Study, examining demographic and diagnosis/treatment outcome predictors.

Methods: Psychological distress, HRQOL, and life satisfaction were measured by the Brief Symptom Inventory-18, the Medical Outcomes Survey Short Form-36, and Cantril Ladder of Life, respectively. A self-report questionnaire provided demographic/health information and medical record abstraction provided cancer/treatment data. Siblings' and survivors' scores were compared using generalized linear mixed models, and predictor effects of demographic and cancer/treatment variables were analyzed by multivariate logistic regression.

Results: Although survivors report greater symptoms of global distress (mean, 49.17; SE, 0.12) than do siblings (mean, 46.64; SE, 0.51), scores remain below population norms, indicating that survivors and siblings remain psychologically healthy. Survivors scored worse than siblings on overall physical (51.30 ± 0.10 versus 54.98 ± 0.44; P < 0.001) but not emotional aspects of HRQOL, but effect sizes were small, other than in vitality. Most survivors reported present (mean, 7.3; SD, 0.02) and predicted future (mean, 8.6; SD, 0.02) life satisfaction. Risk factors for psychological distress and poor HRQOL were female gender, lower educational attainment, unmarried status, annual household income <$20,000, unemployment, lack of medical insurance, having a major medical condition, and treatment with cranial radiation.

Conclusion: Compared with population norms, childhood cancer survivors and siblings report positive psychological health, good HRQOL, and life satisfaction. The findings identify targeted subgroups of survivors for intervention. (Cancer Epidemiol Biomarkers Prev 2008;17(2):435–46)
Association between p53 and Human Papillomavirus in Head and Neck Cancer Survival
Authors: Smith Elaine M. , Wang Donghong , Rubenstein Linda M. , Morris William A. , Turek Lubomir P. , Haugen Thomas H.
Published: February 2008

Background: High-risk human papillomavirus (HPV-HR) is a significant risk factor for head and neck cancer (HNC), abrogating normal p53 function. In addition, HPV and p53 have been associated with prognosis of these tumors but the findings have been inconsistent. We examined p53 expression and HPV-HR individually and jointly for differences in predicting HNC survival.

Methods: HNC patients (n = 294) were evaluated for p53 by immunohistochemical staining. HPV was detected by PCR/dot blot hybridization and sequencing.

Results: HNC tumors showed 48% with p53 overexpression and 27% with HPV-HR. Multivariate analyses showed that p53 positivity was significantly associated with higher risk of disease-specific [hazard ratio (HR); 2.0; 95% confidence interval (95% CI), 1.1-3.7] and recurrence-free mortality (HR, 2.8; 95% CI, 1.4-5.3). HPV− cases had significantly worse disease-specific survival (HR, 2.8; 95% CI, 1.3-6.3) compared with HPV-HR cases. When analyzed jointly, with p53−/HPV-HR tumors as the reference group, p53+/HPV− patients had the worst disease-specific (HR, 5.3; 58% versus 15%, P = 0.006) and recurrence-free survival rates (HR, 9.5; 17% versus 89%, P = 0.001), in contrast to the p53−/HPV− and p53+/HPV-HR groups, which had less elevated and different risks for disease-specific survival (HR, 2.5 and 1.7, respectively) and recurrence-free survival (HR, 4.2 and 7.2, respectively).

Conclusion: Joint assessment of p53/HPV status provides different HRs for each clinical outcome in the four biomarker groups that are distinct from the individual biomarkers. These findings suggest that joint assessment of p53/HPV provides a better indicator of prognosis and potentially different types of treatments. (Cancer Epidemiol Biomarkers Prev 2008;17(2):421–7)
Vegetables and Fruits in Relation to Cancer Risk: Evidence from the Greek EPIC Cohort Study
Authors: Benetou Vassiliki , Orfanos Philippos , Lagiou Pagona , Trichopoulos Dimitrios , Boffetta Paolo , Trichopoulou Antonia
Published: February 2008

Introduction: Vegetables and fruits have long been considered as conducive to cancer prevention, but this view has recently been challenged. We investigated the relation of vegetable and fruit intake with total cancer occurrence in the population-based cohort of the Greek component of the European Prospective Investigation into Cancer and nutrition (EPIC), which is characterized by high consumption of these foods.

Materials and Methods: For a median of 7.9 years, 25,623 participants (10,582 men, 15,031 women) were actively followed-up, contributing 188,042 person-years. Cancer at any site was diagnosed in 851 participants (421 men, 430 women). Dietary intakes were ascertained at enrollment through an extensive, validated, interviewer-administered food frequency questionnaire. Data were analyzed through Cox regression, controlling for potential confounders.

Results: An inverse association of cancer incidence with vegetables and fruits (mutually adjusted) was noted, reaching statistical significance for vegetables among women. When vegetables and fruits were combined, the inverse association with cancer occurrence was statistically significant for the entire cohort [hazard ratio per increasing quintile, 0.94; 95% confidence interval (95% CI), 0.88-0.99], as well as among women (hazard ratio per increasing quintile, 0.90; 95% CI, 0.83-0.98), but not among men (hazard ratio per increasing quintile, 0.95; 95% CI, 0.87-1.04).

Conclusions: In a general population-based Greek cohort, we have found evidence that consumption of vegetables and fruits is inversely associated with incidence of cancer overall, although the associations seem to be weaker than expected on the basis of case-control studies previously undertaken in Greece. (Cancer Epidemiol Biomarkers Prev 2008;17(2):387–92)
Diagnostic Tests Based on Human Basophils: More Potentials and Perspectives than Pitfalls
Authors: de Weck A.L. , Sanz M.L. , Gamboa P.M. , Aberer W. , Bienvenu J. , Blanca M. , Demoly P. , Ebo D.G. , Mayorga L. , Monneret G. , Sainte-Laudy J.
Published: February 2008

For the diagnosis of allergy, cellular basophil activation tests (BAT), e.g. histamine or sulfidoleukotriene release tests, have long been introduced, but the expression of basophil activation markers such as CD63 and CD203c detected by flow cytometry has attracted more recent attention. A recent opinion paper in this Journal has stressed not only the potential but also the possible pitfalls of flow-cytometric BAT. We have applied clinical validation of various BAT in various ways for several years, and our experience shows that these new technologies have more potentials and perspectives than pitfalls. A comprehensive review of clinically validated studies on allergy to aeroallergens, insect venoms, latex, food allergens and drugs, e.g. myorelaxants, β-lactams, pyrazolones and non-steroidal anti-inflammatory drugs, as well as chronic urticaria shows clearly that even with different protocols, reproducible and meaningful results can be obtained. Although the available technologies may still be optimized and better standardized, there are no serious reasons to deprive allergic patients of clinically indicated BAT, which can be performed reliably by any laboratory with allergy and flow-cytometric capacity and expertise.
Sensitization and Allergy to Cannabis sativa Leaves in a Population of Tomato (Lycopersicon esculentum)-Sensitized Patients
Authors: de Larramendi Carlos Hernando , Carnés Jerónimo , García-Abujeta José Luís , García-Endrino Ana , Muñoz-Palomino Elena , Huertas Ángel Julio , Fernández-Caldas Enrique , Ferrer Ángel
Published: February 2008

Background: Cases of allergy to Cannabis sativa have occasionally been reported, but both the allergenic profile and eventual cross-reactivity pattern remain unknown. Objective: To analyze the allergenic profile of a population of patients from Spain sensitized to C. sativa and to characterize the C. sativa leaf extract. Methods: A total of 32 subjects were enrolled in the study: group A, 10 individuals sensitized to tomato, reporting reactions by contact or inhalation to Cannabis; group B, 14 individuals sensitized to tomato, without reactions to Cannabis; group C, 8 individuals not sensitized to tomato and without reactions to Cannabis. Sensitivity to Cannabis, tomato and peach peel, Platanus hybrida and Artemisia vulgaris pollen extracts was measured by skin tests and specific IgE. Individual immunoblots and inhibition experiments with a pool of sera were conducted. Results: All tomato-sensitized subjects (and 1 negative) had positive skin tests to C. sativa leaves and hashish. Specific IgE to C. sativa and peach peel was more common than to tomato. Immunoblot experiments showed 2 prominent bands of 10 and 14 kDa and 2 weakly recognized bands of 30 and 45 kDa. Tomato, peach and A. vulgaris extracts inhibited most of the bands present in C. sativa. P. hybrida inhibited only the high-molecular-weight bands. Conclusion: Sensitization to C. sativa with or without symptoms is frequent among patients in Spain sensitized to tomato. C. sativa leaves are a potential allergenic source and their allergens may cross-react with other allergenic sources from plants (fruit peels and pollen).