bluuebunny/crossref_metadata_2025 huggingface dataset:
Helium and Displacement Damage Produced by 600 MeV Proton Beams in High Purity Aluminum
Authors: Gavillet D , Gotthardt R , Martin J-L , Green SL , Green WV , Victoria M
Published: December 2008

Pure aluminium samples (99.9999%) have been irradiated in the Proton Irradiation Experiment (PIREX) installed in the 600 MeV proton beam of the accelerator in the Swiss Nuclear Research Institute (SIN), at temperatures between 400 K and 500 K and displacement doses between 0.9 and 5 displacements per atom (dpa). Average displacement rate is 3.5 × 10-6 dpa/s.

The specimens were analyzed for both 3He and 4He. Measured helium content is 215 atomic parts per million (appm)/dpa. No diffusional spreading of sodium or helium was measured. The helium bubble structure was examined and shows a swelling of 0.16% at ∼5 dpa.
Modeling of Void Swelling in Irradiated Steels
Authors: Glasgow BB , Wolfer WG
Published: December 2008

The theory of void swelling in irradiated steels has been critically re-examined and a model has been developed from first principles for such fundamental parameters as the bias factors for dislocations and voids, relaxation volumes for interstitials and vacancies, and migration and formation energies for interstitials and vacancies. Four types of growth mechanisms are modeled: self-interstitial emission, loop punching, thermal vacancy exchange, and bias driven growth. The net bias of the system is allowed to change continuously with the evolving microstructure. Combining these growth mechanisms has resulted in a swelling model capable of reproducing some important features of the observed swelling behavior in austenitic stainless steels. For austenitic stainless steels, the model predicts bias driven growth for temperatures between 300°C and 600°C. The long-term swelling rate in this temperature range is roughly independent of temperature and helium concentration and is between 0.7%/dpa (displacements per atom) and 1.3%/dpa. For ferrite phase, the model predicts bias driven growth for temperatures between 300°C and 500°C. However, for this class of steel, the swelling rate is at or below 0.3%/dpa. For bias driven growth, it has been shown that the interstitial and vacancy relaxation volumes ultimately determine the maximum possible swelling rate. It is for this reason that the model predicts a much lower swelling rate for ferrite phase than for austenitic stainless steels.
Effect of Microstructure on the Minimum Critical Radius and Critical Number of Gas Atoms for Swelling
Authors: Coghlan WA , Mansur LK
Published: December 2008

It has been shown theoretically that bias-driven cavity swelling can only occur after either a critical cavity radius has been achieved or a critical number of gas atoms has been accumulated in a cavity. These possibilities merge into each other, as increasing the contained gas lowers the critical radius until at the critical number of gas atoms the minimum critical radius is achieved. With the addition of any more gas, the critical radius disappears and cavity swelling is ensured. It is found that these critical quantities are highly sensitive to irradiation conditions and material parameters. Under fixed irradiation conditions, the critical quantities are remarkably strong functions of dislocation density and bias. These results are described and their implications for the design of swelling-resistant materials are discussed.
Methods of Calibration at a National Laboratory
Authors: Anderson RL
Published: December 2008

Methods used in the Metrology Research and Development Laboratory at the Oak Ridge National Laboratory for calibration of radiation thermometers are described. Sample calibration procedures are included as well as a description of the calibration information system.
Mold Temperature Measurement for Glass-Pressing Processes
Authors: Holman RA
Published: December 2008

The largest use of radiation thermometers within Corning Glass Works is for mold temperature measurement for the glass-pressing process. Pressing television panels at today's high quality would be very difficult without a mold temperature measurement system and the computer manipulation of the quality control data to supervise the mold temperature control loop.

The most critical part of a television panel is the inside surface curvature. The ideal surface is usually defined as a spherical surface. The tolerance for a normal TV panel is ±0.30 mm (±0.012 in.). High resolution display panels are more critical, having a dimensional tolerance only one half as large as TV panels. Panel curvature is a direct (but negative) function of mold temperature. Every 1°C increase in mold temperature results in the panel center being 0.025 mm (0.001 in.) shorter (flatter). Random dimensional variations within a panel take up most of the dimensional tolerance. The result is that each mold is controlled to its own individual temperature set point, ±1°C.

Hot panel and cold panel curvature measurements are correlated by a process computer and used to update the mold temperature set points. The same computer adjusts the mold cooling air to maintain the required mold temperatures.

From the temperature measurement standpoint, the significant problem is the changing emissivity of the mold surface when the mold is new or reconditioned. The selection of a radiation thermometer with a short wavelength was an obvious choice to minimize the effect of emissivity variations. On the negative side, the potential interference from reflected ambient light would require careful shielding. A silicon cell thermometer was chosen for this system. The silicon cell thermometer is a very fast response instrument—that attribute is not required in this specific application but is used in high-speed pressing processes such as automotive headlights.
Radiation Thermometry for Semiconductor Crystal Growing Furnaces
Authors: Helgeland W
Published: December 2008

Single crystals of silicon produced by the Czochralski process are used widely in the production of integrated circuits and other electronic devices. Recent advances in automation of industrial equipment for this process have led to the application of a dual wave band radiation thermometer. The instrument system automatically performs certain critical temperature measurements. In nonautomated equipment, these measurements require the judgement of a trained human operator.

The difficulties of measuring and controlling the temperature at the critical location are discussed, especially with regard to detecting the meltdown end point and to initially establishing the correct temperature for seeding. A description is given of the customized temperature measurement system, which is based upon an existing ratio radiation thermometer. Thermometer output characteristics are described.
Closed-Loop Temperature Control for High-Frequency Electric-Resistance Tube and Pipe Welding Mills
Authors: Udall HN
Published: December 2008

A system for closed-loop temperature control of high-frequency welding systems has been sought for over 20 years; however, until recently the available instrumentation for temperature measurement was not capable of operating in the conditions prevailing on a typical tube or pipe mill. The major problems are: 1. A very small available target size. 2. The positional instability of the target due to changes in incoming material dimensions and mill parameters. 3. The presence of large quantities of cooling water in the immediate weld area with attendant smoke and steam. 4. The possibility of an occasional momentary arc occurring in the weld area under certain mill operating conditions. 5. The very small ratio of the heated material to the power available for heating, leading to the possibility of extremely rapid temperature changes. 6. The presence of a small but significant amount of radio frequency (RF) radiation in the immediate vicinity of the weld.

A combination of the latest developments in color ratio pyrometry, in modern digital control techniques, and in coolant control in the weld area has led to the development of a closed-loop control system which will hold the mean weld temperature constant while rejecting the momentary disturbances to the temperature signal which are inevitable in a normal production process.
Recent Advances and Research Activities in Japan
Authors: Iuchi T
Published: December 2008

Stray radiation and emissivity variation are the most significant causes of measurement error inherent in radiation thermometry. Several methods for reducing errors have been developed by utilizing interreflection of radiation. The first three methods discussed are designed to eliminate stray radiation. The first method, using a water-cooled shielding flange, is applicable for a continuously moving object in a furnace in the range between 200 and 800°C. The second method, having a radiator instead of a cooled shield, is convenient for infurnace measurement higher than 1000°C with accuracy comparable to that of the first method. The third method is designed for the measurement of low-emissivity metals at room temperature where stray radiation is so large that radiation thermometry generally is considered to be impractical. Under the circumstance where the emissivity of the object is not assumed to be constant, the second three methods might be very useful because in these methods the emissivity is simultaneously measured to improve the accuracy of temperature measurement. Specularly reflecting characteristics of the object are utilized in the first and the second methods, while multiple reflection of radiation is used in the last method. Several examples of these methods, routinely used in the steel industry, are introduced. The activities of Japanese societies in the field of radiation thermometry are also surveyed.
Fiber-Optic Thermometry
Authors: Kreider KG
Published: December 2008

A sapphire fiber-optic thermometer which was developed at the National Bureau of Standards (NBS) has been evaluated up to 1600 K. The thermometer operates by emitting radiation from a thin-film metal cup on a sapphire light pipe which is immersed in the hot gas to be measured. Characteristic blackbody emission of the thermometer is transmitted through a controlled optical path to a photodiode. Simultaneous measurements at two wavelengths (596 and 702 nm) were made, and their ratio was used to derive two-color radiation measurements. Several tip geometries and platinum thin-film lengths were investigated to verify blackbody conditions. A reference platinum platinum-rhodium thermocouple was used for calibration and comparison, and a discussion of errors in the two-color ratio method is presented.
A Survey of Asbestos-Related Disease in Trades and Mining Occupations and in Factory and Mining Communities as a Means of Predicting Health Risks of Nonoccupational Exposure to Fibrous Minerals
Authors: Ross M
Published: December 2008

A review based on 36 published epidemiological studies is given of disease patterns that have developed among industrial workers, miners, and millers who had been exposed to dusts of one or more of the commercial asbestos minerals or to dusts from minerals perceived to be asbestos-like. Health data are also reviewed for individuals exposed to asbestos dusts in nonoccupational settings. From the published reports it is clear that there are very significant differences in the health effects of the several asbestos or asbestos-like minerals

Of the commercial asbestos utilized in the United States, about 95% has been chrysotile or “white” asbestos, about 2% amosite or “brown” asbestos, and about 2% crocidolite or “blue” asbestos. The common white asbestos has had the least effect on those occupationally exposed, whereas blue asbestos has had the most effect. Despite the wide dissemination of white asbestos in our environment—in schools, homes, public buildings, brake lining emissions, and so forth—there is little evidence that the very frequent non-occupational exposures to this form of asbestos have caused any harm. On the other hand, nonoccupational exposure to blue asbestos has been conclusively proven to have caused significant mortality. The different health effects of the various forms of asbestos require different regulatory responses and remedial actions.
Membrane Filter Method for Estimating Asbestos Fiber Exposure
Authors: Wylie AG
Published: December 2008

Asbestos exposure is usually evaluated by the membrane filter method recommended by the National Institute for Occupational Safety and Health (NIOSH). The method for estimating fiber exposure was originally applied only to environments in which commercially mined asbestos was being used, but it has now been extended to the mining environment and to other environments in which natural materials containing small quantities of asbestos are found. It has been incorporated into state regulations and procedures and adopted by the industrial hygiene community as an appropriate way to evaluate asbestos exposure. Nonetheless, the membrane filter method suffers from the following serious deficiencies: (1) The aspect ratio criterion used to define and count mineral fibers was arbitrarily chosen and has never been shown to have any relevance to the etiology of asbestos-related diseases or to the actual dimensions of airborne asbestos fibers. (2) Common cleavage fragments of many amphiboles are regulated as asbestos. (3) Many fabricated products containing asbestos and many ores that may contain small quantities of asbestos also contain other substances that cannot be distinguished from asbestos by the membrane filter method. (4) Most airborne asbestos fibers are invisible if the membrane filter method is used. (5) There is no predictable relationship between exposure estimates based on the membrane filter method and the total airborne fiber concentration, as established by electron microscopy. The ratio varies between these two estimates of exposure according to (a) the particular asbestos mineral being evaluated, (b) the degree of development of the asbestiform habit, and (c) the degree of processing to which the mineral has been subjected. Therefore, different total exposures are allowed under existing regulations for different minerals, different mineral habits, and different work environments. A revised standard based on electron microscopy and applying appropriate dimensional criteria is recommended.
Fiber Definition in Occupational and Environmental Asbestos Measurements
Authors: Chatfield EJ
Published: December 2008

Determination of asbestos in occupational air samples is performed by phase contrast optical microscopy (PCM). Any particle with an aspect ratio exceeding 3:1 is considered to be a fiber, and in the PCM method, all fibers longer than 5 µm are counted. Asbestos is measured in ambient air by electron microscopy, and all fibers that can be identified as asbestos are counted. The asbestos fibers are identified by using observations of morphology and a combination of selected area electron diffraction (SAED) and energy dispersive X-ray analysis (EDXA) measurements. The cost of absolute fiber identification, in the legal sense, is often prohibitive and, depending on previous knowledge of the situation, a combination of measurements acceptable as adequate identification may be agreed upon before the analysis is made.

The published information about the relative toxicity of fibers as a function of their dimensions indicates that the fiber definition used in PCM fiber counting excludes many fibers known to induce tumors in animals. For asbestos measurement in ambient air samples, no clear definition of an asbestos fiber exists, and all fibers within the toxic size ranges are examined. Those fibers that are compositionally and crystallographically consistent with asbestos are incorporated into the fiber count.

The relevance of fiber definition in both occupational and ambient air measurements is discussed. The author suggests that the best current information on biological effects should be used to define a new carcinogenicity index, thus bypassing the requirement for arbitrary fiber definitions.
What is Talc?
Authors: Clifton RA
Published: December 2008

Talc is a hydrated magnesium silicate produced by the metamorphosis of dolomite and quartzose rocks or by the hydrothermal alteration of ultramafic and mafic rocks. As the changes are rarely complete and uniform, the rocks usually contain one or more other minerals. In pure form it is the softest of minerals. Talc is an extremely useful and economically important mineral and is, like most materials, hazardous to a degree.

This paper takes the position that talc is a victim. It is a victim of the imprecision of mineral terminology, which does not distinguish between the fibrous and nonfibrous varieties of several amphiboles. It is a victim of the terminology of its own industry, which sold “fibrous talc” for many years. It is victimized because precursor minerals in fibrous habit produce pseudomorphic talc fibers. Those same fibers are sometimes unaltered and present in talc in just enough quantity to give a near truth to claims that talc contains asbestos. Talc is a victim of monitoring methods that are totally nonspecific and call each elongate particle of whatever origin a fiber and, by analogy, asbestos. Most especially, talc is a victim of imprecise asbestos definitions, which allow the inclusion of most amphibole particles of some elongation in those definitions.
Consequences of Using Improper Definitions for Regulated Minerals
Authors: Thompson CS
Published: December 2008

Present trends in government activities aimed at regulating mineral dst exposures in the workplace and in the outside environment indicate a future of extremely difficult, if not impossible, operating conditions for producers and users of mineral products. Using inaccurate and simplistic definitions, governmental agencies have unknowingly indicted a large part of the earth's crust as being extremely hazardous and, in the case of asbestos, cancer causing. Using a simplistic definition of what a fiber is, the government has continued to expand the number and variety of minerals suspected of being as hazardous as or worse than asbestos. This is made clear by recent publications of the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA). The NIOSH paper lists, in addition to asbestos varieties, some 40 “nonasbestos” minerals “which may occur in a fibrous state.” MSHA's publication names 152 “minerals that may occur in fibrous habit.”

Talc is one of the nonfibrous minerals that has become a maligned mineral product, partly because of the rather loose use of the term “talc” by industry in referring to a broad variety of minerals, and partly because of definitions applied to associated minerals present in many talc deposits.

Unless the mineral industry, producers, and consumers, as well as mineral scientists, present a united front in demanding participation in the definition of minerals and mineral products by health researchers and scientists, mineral-related businesses will be confronted by regulations that will be, in the author's estimation, not only oppressive and in many cases prohibitive, but also unnecessary.
Rock Fiber in Nonasbestos Mines— A Suggested Program for Canadian Mines
Authors: Knight G
Published: December 2008

A program is given for the detection and assessment of airborne asbestos and other rock fibers in mines. An interpretation of the results and the difficulties of applying asbestos industry workplace standards are discussed briefly. The major problems are the assessment of fibers when present as a low proportion of the total particles, and the lack of knowledge of the degree of hazard of fibers of different lengths and diameters, which leads to difficulty in comparing these fiber concentrations with those of standards developed mainly in asbestos textile workplaces.
A Definition for Talc
Authors: Ross M
Published: December 2008

The author presents a definition for talc, based on discussions held during a workshop on this subject.
Recent Experiences with Corrosion Beneath Thermal Insulation in a Chemical Plant
Authors: Long VC , Crawley PG
Published: December 2008

Corrosion of carbon and stainless steels under wet thermal insulation can be a serious problem and can be especially prevalent in the humid Gulf Coast area. This paper discusses an inspection program that has been in progress since late 1982 at a ten-year old chemical plant located at La Porte, TX. The program is intended to determine the extent of corrosion damage to major pieces of equipment that has occurred under inhibited calcium silicate insulation finished with aluminum jacketing and to recommend remedial action.

Key elements of a successful inspection program are discussed. A series of pictures is presented that correlate visual external telltale signs with corrosion beneath the insulation. At the time of writing, significant localized corrosion of carbon steel has been found, as well as evidence of incipient stress corrosion cracking of austenitic stainless steel.
Multiaxial Fatigue
Authors: Miller KJ , Brown MW
Published: December 2008

Description

Combines international schools of thought on the behavior of materials subjected to multiaxial fatigue. Gives designers simplified methods of analysis that are applicable to practical situations involving complex street cycling. Shows that significant progress has been made in predicating finite fatigue life behavior, namely, that induction of stresses on two or three axes in fatigue experiments provides valuable information on the micro mechanisms of fatigue crack formation and growth and the uses and limitations of multiaxial correlation factors.
Fatigue at Low Temperatures
Authors: Stephens RI
Published: December 2008

Description

Contains basic and applied research results on the fatigue behavior of materials subjects to low temperature, both cryogenic and noncryogenic. Divided into two sections
Delamination and Debonding of Materials
Authors: Johnson WS
Published: December 2008

Description

Discusses the analysis, testing, and detection of the delamination of composite materials and the debonding of adhesive joints. 25 papers examine stress analysis, mechanical behavior, and fractography/NDI.
Corrosion of Metals Under Thermal Insulation
Authors: Pollock WI , Barnhart JM
Published: December 2008

Description

Provides the latest information on the serious corrosion problems that can occur to thermally insulated plant equipment, tankcage and piping components if the insulation becomes wet and reviews the various control and inspection methods being used and under development
Radiation-Induced Changes in Microstructure: 13th International Symposium (Part I)
Authors: Garner FA , Packan NH , Kumar AS
Published: December 2008

Description

STP 955 resulted from a major international forum for the exchange and discussion of both the fundamental and technological aspects of behavior change in materials exposed to radiation environments. 66 papers comprise this book whose contents have been categorized into seven distinct technical areas: radiation-induced defects and their diffusion; neutron-induced swelling; charge particle-induced swelling; theory of swelling and irradiation creep; microstructural evolution; solute segregation and phase stability; and effects of implantation.
Degradation of Metals in the Atmosphere
Authors: Dean SW , Lee TS
Published: December 2008

Description

Paper present current research results on the corrosion of metals in the atmosphere, show current thinking on mechanisms of atmospheric corrosion, and document how changes in the atmosphere have affected the corrosion of metals. This book provides convenient access to technical data from recent tests, long term test programs, and field experience, including data on new materials of construction.
Influences of Fragmentation on Three Species of Native Warmwater Fishes in a Colorado River Basin Headwater Stream System, Wyoming
Authors: Compton Robert I. , Hubert Wayne A. , Rahel Frank J. , Quist Michael C. , Bower Michael R.
Published: December 2008

We investigated the effects of constructed instream structures on movements and demographics of bluehead suckers Catostomus discobolus, flannelmouth suckers C. latipinnis, and roundtail chub Gila robusta in the upstream portion of Muddy Creek, an isolated headwater stream system in the upper Colorado River basin of Wyoming. Our objectives were to (1) evaluate upstream and downstream movements of these three native species past a small dam built to divert irrigation water from the stream and a barrier constructed to prevent upstream movements of nonnative salmonids and (2) describe population characteristics in stream segments created by these structures. Our results indicated that upstream and downstream movements of the three target fishes were common. Fish of all three species moved frequently downstream over both structures, displayed some upstream movements over the irrigation diversion dam, and did not move upstream over the fish barrier. Spawning migrations by some fish into an intermittent tributary, which was not separated from Muddy Creek by a barrier, were observed for all three species. Both the irrigation diversion dam and the fish barrier contributed to fragmentation of the native fish populations, and considerable differences in population features were observed among segments. The instream structures may eventually cause extirpation of some native species in one or more of the segments created by the structures.
Influence of the Moran Effect on Spatiotemporal Synchrony in Common Carp Recruitment
Authors: Phelps Quinton E. , Graeb Brian D. S. , Willis David W.
Published: December 2008

Climatic variation and dispersal are two primary factors thought to induce recruitment synchrony in fish populations. We hypothesized that climate factors correlated across a broad geographical scale (i.e., the Moran effect) would induce synchrony in recruitment for common carp Cyprinus carpio among 18 glacial lakes across a 175‐km2 area in eastern South Dakota. Cross‐correlation analysis indicated that common carp population fluctuations were highly synchronous among lakes. To evaluate the influence of the Moran effect on recruitment, we examined several candidate models using an information‐theoretic approach. The model with the most support included the interaction of temperature, precipitation, and wind during the open‐water period. This model indicated that the effects of any one of these climate variables on recruitment strength depended on the level of each of the other variables in any given year. Our results suggest that common carp populations in the Midwestern United States exhibit synchronous recruitment across regionwide geographic areas as a result of climatic variability.
Factors influencing trends of polychlorinated naphthalenes and other dioxin-like compounds in lake trout (Salvelinus namaycush) from Lake Ontario, North America (1979–2004)
Authors: Gewurtz Sarah B. , Lega Rocsana , Crozier Patrick W. , Whittle D. Michael , Fayez Laila , Reiner Eric J. , Helm Paul A. , Marvin Chris H. , Tomy Gregg T.
Published: December 2008

Concentrations of polychlorinated naphthalenes (PCNs) were determined in archived lake trout (Salvelinus namaycush) from Lake Ontario, North America, collected between 1979 and 2004 to evaluate their temporal trends and the factors influencing their trends. Concentrations of PCNs, as well as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and non- and mono-ortho-substituted polychlorinated biphenyls (DL-PCBs), which were measured for comparative purposes, declined by eight-, seven-, and fivefold, respectively, between 1979 and 2004. Apparent elimination rate constants (k2) were calculated as the slopes of the regression lines of concentration versus time for PCN, DL-PCB, and PCDD/F congeners to compare the rate of decrease among congeners within and between compound classes. The k2 values for PCNs that had two pairs or three adjacent carbons unsubstituted with chlorine (congeners that can be biotransformed by vertebrates) were not significantly different from zero, indicating no decline in fish. For PCN congeners having no adjacent carbons unsubstituted with chlorine, the k2 values generally increased with hydrophobicity and degree of chlorination. This pattern differed from that of PCDD/Fs and DL-PCBs and from previous findings for non-DL-PCBs, for which the rate of contaminant decline decreased with hydrophobicity, and the pattern also differed from expectations based on thermodynamics. Differences in the rate of decline of PCN congeners may be caused by changes in source or mixture formulations over time and/or metabolic dechlorination of the less stable, higher-chlorinated PCNs 73, 74, and 75 to lower-chlorinated congeners. Based on suggested dioxin toxic equivalency factors, PCN concentrations in these whole lake trout may be sufficient to trigger consumption restrictions in Ontario, Canada, and our results suggest that PCNs merit incorporation into monitoring and assessment programs.
Detection of Herpesviruses and Periodontal Pathogens in Subgingival Plaque of Patients With Chronic Periodontitis, Generalized Aggressive Periodontitis, or Gingivitis
Authors: Imbronito Ana Vitória , Okuda Osmar Shizuo , Maria de Freitas Nivea , Moreira Lotufo Roberto Fraga , Nunes Fabio Daumas
Published: December 2008

Background: Herpesviruses may be related to the etiology of aggressive periodontitis (AgP) and chronic periodontitis (CP) by triggering periodontal destruction or by increasing the risk for bacterial infection. This case‐control study evaluated the presence of herpes simplex virus type I (HSV‐1), Epstein‐Barr virus type I (EBV‐1), human cytomegalovirus (HCMV), Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans), Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia (previously T. forsythensis) in patients with generalized AgP (AgP group), CP (CP group), or gingivitis (G group) and in healthy individuals (C group).

Methods: Subgingival plaque samples were collected with paper points from 30 patients in each group. The nested polymerase chain reaction (PCR) method was used to detect HSV‐1, EBV‐1, and HCMV. Bacteria were identified by 16S rRNA‐based PCR.

Results: HSV‐1, HCMV, and EBV‐1 were detected in 86.7%, 46.7%, and 33.3% of the AgP group, respectively; in 40.0%, 50.0%, and 46.7% of the CP group, respectively; in 53.3%, 40.0%, and 20.0% of the G group, respectively; and in 20.0%, 56.7%, and 0.0% of the C group, respectively. A. actinomycetemcomitans was detected significantly more often in the AgP group compared to the other groups (P <0.005). P. gingivalis and T. forsythia were identified more frequently in AgP and CP groups, and AgP, CP, and G groups had higher frequencies of P. intermedia compared to the C group.

Conclusion: In Brazilian patients, HSV‐1 and EBV‐1, rather than HCMV, were more frequently associated with CP and AgP.
Involvement of Interleukin‐1 Genotypes in the Association of Coronary Heart Disease With Periodontitis
Authors: Geismar Karen , Enevold Christian , Sørensen Lars Korsbæk , Gyntelberg Finn , Bendtzen Klaus , Sigurd Bjarne , Holmstrup Palle
Published: December 2008

Background: Epidemiologic studies demonstrated an association between periodontitis (PE) and coronary heart disease (CHD). The coexistence of the two disease entities could be dependent on mutual risk factors, and polymorphism of the interleukin (IL)‐1 gene cluster associated with the severity of PE might also be involved in the pathogenesis of CHD.

Methods: The study consisted of 225 dentate white subjects, including 97 patients with CHD and 128 controls. Patients with confirmed diagnoses of CHD were recruited after being discharged from a cardiology department, and controls without CHD were recruited consecutively from the Copenhagen City Heart Study. Mean alveolar bone level (ABL) was measured on radiographs. ABL was stratified into ABL1 (ABL ≤2 mm), ABL2 (2 mm 4 mm). Genotypes were analyzed by amplifying the polymorphic regions of the IL‐1 gene cluster using polymerase chain reaction, followed by restriction digestion and gel electrophoresis.

Results: In the univariate analysis, allele 2 of IL‐1B+3954 and IL‐1B−511 was associated with ABL (P = 0.040 and P = 0.039, respectively), whereas no association was found with allele 2 of IL‐1A+4845 or IL‐1RN variable number tandem repeat (VNTR) (P = 0.445 and P = 0.375, respectively). A lower ABL was associated with the occurrence of allele 2 of IL‐1B−511. The multiple logistic regression analysis also showed a significant association of allele 1 of IL‐1B−511 with high ABL (P = 0.049) and of allele 2 of IL‐1A+4845 with high ABL among individuals with CHD (P = 0.050). There was no association between any of the polymorphisms of IL‐1 and CHD in the univariate or multiple analyses. However, in a binary multiple logistic regression model, carriage of allele 1 of IL‐1RN VNTR was found to be associated with the occurrence of both CHD and ABL3 (P = 0.016).

Conclusion: Allele 1 of IL‐1RN VNTR may be associated with the coexistence of CHD and PE in a multiple regression model.
Humoral Factors Released From Human Periodontal Ligament Cells Influence Calcification and Proliferation in Human Bone Marrow Mesenchymal Stem Cells
Authors: Mizuno Noriyoshi , Ozeki Yoshitaka , Shiba Hideki , Kajiya Mikihito , Nagahara Takayoshi , Takeda Katsuhiro , Kawaguchi Hiroyuki , Abiko Yoshimitsu , Kurihara Hidemi
Published: December 2008

Background: Transplantation of bone marrow mesenchymal stem cells (MSCs) is believed to be a new modality for periodontal tissue regeneration. However, little is known about the factors that influence the functions of the transplanted MSCs. Periodontal ligament cells may be implicated in regulating MSC functions.

Methods: To examine the effect of humoral factors (HFs) produced by human periodontal ligament (HPL) cells on human MSC (hMSC) gene expression, hMSCs were cocultured separately with HPL cells. The gene expression of the hMSCs was analyzed by microarray. Moreover, the effect of conditioned medium (CM) from cultures of HPL cells (CM‐HPL cells) on the proliferation and mineralizing capacity of hMSCs was examined.

Results: Thirty‐five genes whose expressions were upregulated more than two‐fold and 32 genes whose expressions were downregulated more than two‐fold were identified in hMSCs cocultured separately with HPL cells. CM‐HPL cells prevented calcification in hMSCs cultured with bone morphogenetic protein‐2 but not dexamethasone. CM‐HPL cells stimulated cell proliferation in hMSCs, whereas CM from culture of human osteoblasts did not influence the proliferation.

Conclusions: To the best of our knowledge, this is the first study on the global gene expression of MSCs cocultured with periodontal ligament cells. A particular humoral factor released from periodontal ligament cells is suggested to affect differentiation and proliferation in MSCs.
Association Between Involuntary Smoking and Salivary Markers Related to Periodontitis: A 2‐Year Longitudinal Study
Authors: Nishida Nobuko , Yamamoto Yumiko , Tanaka Muneo , Kataoka Kosuke , Kuboniwa Masae , Nakayama Kunio , Morimoto Kanehisa , Shizukuishi Satoshi
Published: December 2008

Background: Insufficient data exist regarding the longitudinal influence of involuntary smoking on periodontitis progression. This study examined the relationship between involuntary smoking and periodontitis progression and the effects of involuntary smoking on salivary inflammatory and microbiologic markers related to periodontitis.

Methods: Participants were recruited during annual health checkups in 2003 and 2005. In 2005, 200 of 273 (73%) Japanese employees examined at baseline underwent periodontal measurements, including clinical attachment level (CAL) and probing depth (PD). Periodontitis progression was identified when a subject displayed one or more teeth with an increase ≥2.0 mm in CAL and PD during the 2 years. Salivary marker levels, including cotinine, were determined by enzyme assay, including enzyme‐linked immunosorbent assay. The proportions of six periodontal pathogens in saliva were assessed using real‐time polymerase chain reaction methodology. Based on receiver‐operating characteristic analysis, non‐, involuntary, and active smokers were defined as subjects exhibiting salivary cotinine levels of 0, 1 to 7, and ≥8 ng/ml, respectively.

Results: By simple logistic regression analysis, age, alcohol consumption, smoking, breakfast habits, and working hours were related to the risk for significant periodontitis progression. Multiple logistic regression analysis revealed significantly higher periodontitis odds ratios (OR) in involuntary (OR = 2.23; 95% confidence interval [CI]: 1.03 to 4.83) and active (OR = 2.27; 95% CI: 1.02 to 5.04) smokers relative to non‐smokers following adjustment for covariates. Levels of salivary markers, including albumin, aspartate aminotransferase, and lactoferrin, were significantly elevated in involuntary smokers relative to non‐smokers. In contrast, the percentages of periodontal pathogens did not differ between the smoking groups, with the exception of Prevotella nigrescens, which displayed significantly lower levels in involuntary smokers compared to non‐smokers.

Conclusion: Involuntary smoking increased the inflammatory response and was associated with a greater risk for periodontitis progression.
Pain Perception and Anxiety During Scaling in Periodontally Healthy Subjects
Authors: Guzeldemir Esra , Toygar Hilal Uslu , Cilasun Ulkem
Published: December 2008

Background: Dental pain, anxiety, and fear may result in avoiding dental treatment. In this study, we aimed to evaluate patients' pain perception during scaling and its relationship with dental anxiety.

Methods: One hundred thirteen patients (72 women and 41 men; mean age, 35.59 ± 9.28 years) participated. Pain levels after scaling were assessed with a visual analog scale (VAS) and an anxiety questionnaire consisting of seven questions, each with five possible answers.

Results: The patients were asked to indicate their pain level on a 100‐mm VAS, and the mean VAS score was 19.91 ± 17.76 mm. No age and gender differences with regard to pain perception were found. VAS scores were significantly higher in non‐smokers (P <0.001); there was a slightly significant relationship between smoking and pain (0.264; P <0.05). The anxiety score ranged from 7 to 35; the mean anxiety score was 14.00 ± 5.30 (range, 7 to 29). The anxiety score was significantly higher in women (P <0.001). The only question correlated with pain during scaling in men was, “How fearful are you of having your teeth cleaned?” (0.322; P = 0.040). Scores for patients aged 29 to 39 years were significantly higher than scores for those aged 51 to 61 years (P <0.01).

Conclusions: Although most patients experienced limited pain during scaling, a significant relationship was found between pain and smoking. Women and patients aged 30 to 40 years are likely to be more anxious during scaling. The question, “How fearful are you of having your teeth cleaned?” may not adequately cover all aspects of anxiety for patients' experience of pain during scaling. Clinicians should determine individual treatment approaches to reduce patients' fear, pain, and anxiety related to scaling.
Posterior Implant Single‐Tooth Replacement and Status of Adjacent Teeth During a 10‐Year Period: A Retrospective Report
Authors: Misch Carl E. , Misch‐Dietsh Francine , Silc Jennifer , Barboza Eliane , Cianciola Louis J. , Kazor Christopher
Published: December 2008

Background: The purpose of this case series study was to evaluate posterior single‐tooth implant survival and the long‐term conditions of the adjacent teeth.

Methods: A retrospective evaluation of 1,162 consecutive patients with a single missing posterior tooth treated with 1,377 external hex implants supporting 1,365 restorations surrounded by natural teeth over a 1‐ to 10‐year period was reviewed from four private offices. Implant survival data were collected relative to stage I to stage II healing, stage II to prosthesis delivery, and prosthesis delivery to up to 10 years of follow‐up. Long‐term adjacent tooth conditions were assessed, including decay, endodontic therapy (root canal therapy [RCT]), and/or extraction during the follow‐up period.

Results: Of the 1,377 implants inserted, there were 11 surgical failures from stage I to stage II healing. There was one failure from stage II healing to prosthesis delivery. There were two prosthetic‐phase failures. The surgical success rate was 99.2%, whereas the overall survival rate was 98.9% at an average of 61 months of follow‐up (range, 12 to 125 months). A total of 2,589 adjacent teeth were followed during the study. No natural adjacent tooth was lost during this period. Interproximal decay developed in 129 adjacent teeth (5%), and nine adjacent teeth required RCT (0.4%) as a result of decay or restoration.

Conclusions: The use of single‐tooth implants as replacements for posterior missing teeth is a viable long‐term treatment. Adjacent natural teeth complications are minimal for as long as 10 years after implant insertion.
Elements of Fractal Generalization of Dual‐Porosity Model for Solute Transport in Unsaturated Fractured Rocks
Authors: Bolshov Leonid , Kondratenko Peter , Matveev Leonid , Pruess Karsten
Published: December 2008

In this study, new elements were developed to generalize the dual‐porosity model for moisture infiltration and solute transport in unsaturated rocks, taking into account fractal aspects of the percolation process. Random advection was considered as a basic mechanism of solute transport in self‐similar fracture systems. In addition to spatial variations in the infiltration velocity field, temporal fluctuations were also taken into account. The rock matrix, which is a low‐permeability component of the heterogeneous geologic medium, acts as a trap for solute particles and moisture. Scaling relations were derived for the moisture infiltration flux, the velocity correlation length, the average velocity of infiltration, and the velocity correlation function. The effect of temporal variations in precipitation intensity on the infiltration processes was analyzed. It showed that the mode of solute transport is determined by the power exponent in the advection velocity correlation function and the dimensionality of the trapping system, both of which may change with time. Therefore, depending on time, various transport regimes may be realized: superdiffusion, subdiffusion, or classical diffusion. The complex structure of breakthrough curves arising from changes in the transport regimes was also examined. A renormalization of the solute source strength due to characteristic fluctuations of highly disordered media was established.
Predicting Air Permeability in Porous Media with Variable Structure, Bulk Density, and Water Content
Authors: Poulsen Tjalfe G. , Blendstrup Helle
Published: December 2008

Air permeability in unstructured porous media can often be predicted directly from air‐filled porosity based on one or two measurements of air permeability at different air‐filled porosities using existing predictive models. In structured media and media that change their physical characteristics (bulk density, water content, organic matter content, etc.) with time, the relationship between air permeability and air‐filled porosity is often very complex and consequently models for predicting air permeability in such media are not yet well established. We developed a simple model concept for predicting air permeability in porous media with variable structure. Predictions are based on water content, air‐filled porosity, and dry bulk density and the model uses a very limited set of input data. The model is able to predict air permeability throughout the entire water content–bulk density domain. A set of four measurements of air permeability at different values of water content and dry bulk density is required as input. The model was tested against a set of air permeability data from six porous materials (a total of 236 measurements) representing a wide range of material types, organic matter contents, water contents, and dry bulk densities. Excellent agreement between measured and predicted air permeability values was found except at very low values of air permeability for some of the materials.
Near‐Saturated Hydraulic Properties of Macroporous Soils
Authors: Jarvis Nicholas
Published: December 2008

Simulations with dual‐permeability models are sensitive to the description of the hydraulic properties in the near‐saturated region. Yet mostly due to a lack of supporting data, very little is known about the suitability of different approaches or how the parameters describing hydraulic functions in these models can be estimated. In this study, a simple model of macropore hydraulic properties was derived from the generalized Kozeny–Carman equation, the pore‐scale tortuosity factor proposed by Fatt and Dykstra, and the functional form for the soil water characteristic described by Ross and colleagues. The model was fitted to published data on near‐saturation wetting characteristics and hydraulic conductivity for seven soils—five undisturbed soils in the field and two repacked under laboratory conditions. Considering the difficulties involved in measuring small changes in water content in the region close to saturation, the model described the field data quite well providing the tortuosity factor was set to zero. For a small data set consisting of near‐saturated conductivity measurements on 12 Swedish soils, the pore size distribution parameter in the Ross et al. model could be related to clay content and macroporosity. It was concluded that this simple model shows promise, both as a description of macropore hydraulic properties in dual‐permeability models and as a conceptual framework to support the development of pedotransfer functions for near‐saturated and saturated hydraulic conductivity.
Antecedent Hypoglycemia Impairs Autonomic Cardiovascular Function
Authors: Adler Gail K. , Bonyhay Istvan , Failing Hannah , Waring Elizabeth , Dotson Sarah , Freeman Roy
Published: December 2008

OBJECTIVE— Glycemic control decreases the incidence and progression of diabetic complications but increases the incidence of hypoglycemia. Hypoglycemia can impair hormonal and autonomic responses to subsequent hypoglycemia. Intensive glycemic control may increase mortality in individuals with type 2 diabetes at high risk for cardiovascular complications. We tested the hypothesis that prior exposure to hypoglycemia leads to impaired cardiovascular autonomic function.

RESEARCH DESIGN AND METHODS— Twenty healthy subjects (age 28 ± 2 years; 10 men) participated in two 3-day inpatient visits, separated by 1–3 months. Autonomic testing was performed on days 1 and 3 to measure sympathetic, parasympathetic, and baroreflex function. A 2-h hyperinsulinemic [hypoglycemic (2.8 mmol/l) or euglycemic (5.0 mmol/l)] clamp was performed in the morning and in the afternoon of day 2.

RESULTS— Comparison of the day 3 autonomic measurements demonstrated that antecedent hypoglycemia leads to 1) reduced baroreflex sensitivity (16.7 ± 1.8 vs. 13.8 ± 1.4 ms/mmHg, P = 0.03); 2) decreased muscle sympathetic nerve activity response to transient nitroprusside-induced hypotension (53.3 ± 3.7 vs. 40.1 ± 2.7 bursts/min, P < 0.01); and 3) reduced (P < 0.001) plasma norepinephrine response to lower body negative pressure (3.0 ± 0.3 vs. 2.0 ± 0.2 nmol/l at −40 mmHg).

CONCLUSIONS— Baroreflex sensitivity and the sympathetic response to hypotensive stress are attenuated after antecedent hypoglycemia. Because impaired autonomic function, including decreased cardiac vagal baroreflex sensitivity, may contribute directly to mortality in diabetes and cardiovascular disease, our findings raise new concerns regarding the consequences of hypoglycemia.