bluuebunny/crossref_metadata_2025 huggingface dataset:
The Applicability of Small and Ultra-Small Fracture Toughness Specimens for Material Characterization
Authors: Valo M , Planman T , Wallin K
Published: March 2009

In the study fracture toughness tests were performed with 20% sidegrooved small (10*10*55 mm) and ultra-small (3*4*27,5*5*27 and 5*10*55 mm) specimens. The objective of the study was to experimentally determine the measuring capacity of small specimens and to check the data against the statistical cleavage fracture model developed by VTT. Two pressure vessel steels, an A533B base metal (HSST-3) and a VVER base metal of 15Kh2MFA type were used in the study. Most of the tests were performed in the transition range and cleavage fracture was observed in the tests. Additional tests were conducted in the temperature range of ductile material behavior. The data indicate that the T0 (100 MPa√m) reference temperature can be determined even with 3*4 mm specimens in consistency with larger specimens by applying only the statistical specimen size correction, without any consideration on specimen constraint. The fracture resistance curves measured with 5*10 mm specimens give a good technical estimation for the larger specimen R-curves.
Developing Fracture Assessment Methods for Fusion Reactor Materials with Small Specimens
Authors: Odette GR , Edsinger K , Lucas GE , Donahue E
Published: March 2009

Design and operation of fusion reactors will require a temperature-dependent effective toughness [Ke(T)] data base. Effective toughness is a function of intrinsic metallurgical/microstructural factors, degraded by irradiation, and extrinsic factors, such as size and geometry. Standard fracture mechanics is inadequate, since the presumption of geometrically independent crack tip stress/strain fields does not apply to either small specimens or in thin-walled structures with shallow cracks. More general approaches to measuring and applying Ke(T) data are described for cleavage initiation in steels and vanadium alloys. The critical stress-critical area (σ*/A*) mechanism of cleavage initiation is demonstrated using a confocal microscopy/fracture reconstruction method that can also directly measure Ke. The σ*/A* model is combined with finite element method (FEM) simulations of crack tip fields to: a) predict Ke(T) for F-82H as a function of size; and b) directly adjust Ke(T) data to a common test geometry. A simpler master curve-(temperature) shift method is also described. Changes in yield stress due to irradiation or strain rates can be related to the shifts. Indeed, tensile properties as a function of temperature, strain rate and alloy condition are required by all assessment methods. Physically-based small specimen methods will reduce enormously what would otherwise be a prohibitive amount of testing.
Estimation of Fracture Toughness Values for Titanium Alloy Using Small Centre Notched Round Specimens
Authors: Sarchamy D , Burns MG
Published: March 2009

There are many industries where the materials employed, and the components manufactured, often cannot provide the standard specimens required by current fracture toughness test methods, due to insufficient section thickness. With the growing importance of Damage Tolerance criteria it is evident that reliable data must be available to Design, Production, and, where necessary, Failure Investigation personnel in these areas. This investigation utilised forged ELI-grade titanium -6A1 -4V (wt%) material. Compact Tension specimens and Circumferrentially Notched Round test pieces were extracted from adjacent positions, with identical crack planes, to allow comparison of the results. Miniature test pieces were precracked under rotating bending fatigue. The results obtained from the miniature test pieces are accurate and consistent with those produced by the standard specimens.
Reconstitution of Fracture Toughness Specimen for Surveillance Test
Authors: Tomimatsu M , Kawaguchi S , Iida M
Published: March 2009

Fracture toughness is one of the most important material properties that influences the integrity of reactor pressure vessels (RPVs). Methods for reconstitution of fracture toughness specimen have been developed preliminarily in order to increase the number of fracture toughness data of irradiated RPV steels. The specimen adopted in this study was a 12.5mm thick compact specimen (1/2TCT). The size of insert material, which is removed from the assumed broken specimen, is 13 × 15 × 12.5mm3. Materials used were two kinds of unirradiated RPV steels. Welding procedures investigated were CO2 laser beam welding(LBW) and electron beam welding(EBW). Several welding parameters, such as welding current, speed of travel, etc. were varied parametrically. Then optimum welding conditions of both weldings for reconstitution of CT specimen were investigated. It was found that fracture toughness values obtained from the reconstituted CT specimens of two steels are almost the same as those from original specimens in both the transition and the upper shelf temperature ranges. It turns out that the above methods can be applied for the reconstitution of irradiated fracture toughness specimen in hot cell.
Reconstitution of Charpy Impact Specimens by Surface Activated Joining
Authors: Nishiyama Y , Fukaya K , Onizawa K , Suzuki M , Nakamura T , Kaihara S , Sato A , Yoshida K
Published: March 2009

The method of surface activated joining (SAJ) was applied to reconstitution of Charpy impact specimens. SAJ makes use of friction at material surfaces in a vacuum to achieve joining without melting. This paper describes verification to apply SAJ to reconstitution of Charpy impact specimens with unirradiated reactor pressure vessel plate materials, JRQ and HSST-03. By optimizing joining parameters, heat affected zones induced by friction had a width of about 1 mm to either side of the joint. The original Charpy impact properties in the transition region were reproduced from reconstituted impact specimens with the insert length of 10 mm. The maximum temperature during joining was appreciably low at a given distance from the joining interface, compared with other conventional welding techniques.
Miniature Shear Punch Test with On-Line Acoustic Emission Monitoring for Assessment of Mechanical Properties
Authors: Kasiviswanathan KV , Hotta SK , Mukhopadhyay CK , Raj B
Published: March 2009

This paper describes the use of acoustic emission monitoring during the shear punch tests to reduce the error involved in the estimation of mechanical property data, especially in the yield strength and strain hardening exponent. Tests have been carried out on a range of materials including AISI type 304 stainless steel containing various amounts of cold work. These data from the shear punch test are compared with tensile property measurements on identical materials. The on-line monitoring capability of acoustic emission technique has been successfully utilized for accurate evaluation of mechanical property data from the shear punch tests.
The Use of a Small Punch Test Procedure to Determine Mechanical Properties
Authors: Lee WK , Metzger DR , Donner A , Lepik OE
Published: March 2009

A small ball-punch-on-rectangular-specimen design was developed to test materials such that cracking occurs along a desired orientation. Energy to fracture is determined from the punch load and displacement, which are measured continuously during the test. A three dimensional ¼ finite element model was formulated to simulate the punch test. The calculated load-displacement and stress-strain curves compared reasonably well with the experimental results. The plastic strain distribution was consistent with the observed location of fracture, and the reduction in thickness was also in agreement with measurements taken from deformed test specimens. Room temperature and 250 °C tests were performed on a SA106 grade B steel for two orientations, C-L and L-C. Empirically, the punch test's energy to break results showed a correlation with fullsize JIc results. The test method can also be used to determine the Ductile-to-Brittle-Transition-Temperature (DBTT) behavior of steel. An ASTM A533, grade B material was tested to -180 °C and the typical DBTT behavior, relative to Charpy test results, was observed. Although the technique described in this paper shows some correlations with JIc and the DBTT, the scatter is larger than results for full-size specimens.
The Prediction of Fracture Toughness Properties from 3MM Diameter Punch Discs
Authors: Geary W , Dutton JT
Published: March 2009

A small punch test method has been developed utilising 3mm diameter discs. Experiments have been conducted on three structural steels and one high strength offshore steel. The relationships between data derived from the punch test load displacement curves and uniaxial tensile, fracture toughness and Charpy tests were explored. The work has highlighted a need for standardisation of the test method and of specimen sizes if further progress is to be made.
The Use of Interfacial Test Methods in Composite Materials Development
Authors: Pitkethly MJ
Published: March 2009

Interfacial testing generates physical information about the fiber matrix interface in a variety of forms. In recent years, there has been considerable discussion about the reliability of the tests and the compatibility of the data generated. One question that has only marginally been addressed is what is required from interfacial test methods to support the rest of the composites community in the understanding and development of fiber-reinforced composite materials. In this paper, the requirements of composite developers and designers are evaluated and related to the information generated by existing test methods. Data are presented demonstrating the significant influence that interface has on macroscopic properties. The relationship of this type of data to interfacial test techniques currently used is also addressed. Those interfacial test methods in use fall into three basic types and each generates information under different loading conditions. An attempt has been made to correlate these conditions to failure processes that occur in full-scale composites. This has clarified where there are deficiencies in both the test methods used and the type of data required. If interfacial property evaluation in composite materials is to become an integral part of composite design, then there needs to be an improved correlation between data generated and end-user requirements
Effect of Temperature and Fiber Coating on the Strength of E-Glass Fibers and the E-Glass/Epoxy Interface for Single-Fiber Fragmentation Samples Immersed in Water
Authors: Schultheisz CR , Schutte CL , McDonough WG , Macturk KS , McAuliffe M , Kondagunta S , Huntson DL
Published: March 2009

The effect of absorbed moisture on the strengths of fibers and the fiber/matrix interface for an epoxy reinforced with continuous fibers of E-glass is under investigation. Single-fiber fragmentation tests of glass/epoxy model composites have shown degradation of the strengths of both the fiber and the interface after immersion in water. The fragmentation specimens were tested as-fabricated and after immersion in distilled water at 25 and 75°C for more than 4000 h. Two coatings were applied to the fibers, one epoxy-compatible and the other vinylester-compatible, in an effort to include the initial interfacial shear strength as a variable. Analyses of the fragmentation test results adapting the approach of Wagner and coworkers were used to determine moisture-induced changes in the fiber strength, making it possible to also evaluate changes in the interfacial strength.
Fiber/Matrix Interface Effect on Monotonic and Fatigue Behavior of Unidirectional Carbon/Epoxy Composites
Authors: Large-Toumi B , Salvia M , Vincent L
Published: March 2009

This paper deals with the study of the influence of fiber/matrix interface on the fatigue behavior of unidirectional carbon/epoxy composites. These materials are based on a T300/DGEBA/DDM system and the sizing nature, fiber oxidation, and degree of cure are varied independently. The interfacial properties were evaluated by the microdebonding test. The results show the good adhesion developed in our systems. The epoxy specific sizing increases the interfacial strength and the lack of oxidation treatment slightly decreases it.

In three-point bending, the failures of the composites all appear on the compressive side, due to undesirable fiber kinking phenomena. To overcome these difficulties, which are linked to the compressive effects of the loading nose, a compression bending test was adapted to perform monotonic as well as fatigue tests. Under this configuration, progressive failure initiates on the tensile side and slowly propagates through the thickness of the sample. The Wöhler's curves can be plotted with moderate scattering. They are very flat, in comparison to the GFRP curves, and thus show the excellent fatigue behavior of these materials.

The effect of the interface on both the monotonic and cyclic behaviors is clearly pointed out. The lack of fiber oxidation increases the monotonic properties without changing the fatigue resistance significantly. On the other hand, a slight matrix under-cure leads to a better intrinsic fatigue resistance but to smaller properties-to-failure. The analysis of both monotonic and cyclic properties reveals the existence of different optima depending on the interfacial properties. The “best” interface does not exist; it is a function of both the fiber/matrix system properties and the mechanical performance studied.
Engine Coolant Technology, Performance, and Life for Light-Duty Applications
Authors: Turcotte DE , Lockwood FE , Pfitzner KK , Meszaros LL , Listebarger JK
Published: March 2009

Recently there has been interest by motor vehicle manufacturers in developing longer-lived automotive engine coolants with an emphasis on organic acid technology (OAT) [1]. Paradoxically, the lifetime of conventional technology remains largely undefined. Concerns arising from the depleting nature of silicate have led to modern conservative change recommendations of 30 000 to 50 000 miles (∼48 279 to 80 464 km) [2].

In the present work, laboratory bench test, engine dynamometer and vehicle service data from traditional silicate, hybrid and nonsilicate coolants are compared and contrasted. A new electrochemical test is used to examine passivation kinetics on aluminum. It is shown that performance and lifetime are independent of chemistry and cannot be generalized. Examples include an American silicate coolant with excellent performance on high-heat-rejecting aluminum (80 W/cm2), European and American silicate coolants with performance defined lifetimes in excess of 300 000 miles (482 790 km), and an OAT coolant with laboratory high lead solder protection. It is concluded that the primary benefit of OAT is to meet global specifications that include chemical limitations.
Overview of Used Antifreeze and Industrial Glycol Recycling by Vacuum Distillation
Authors: Frye DK , Chan K , Pourhassanian C
Published: March 2009

A leading method of reclaiming ethylene glycol from both used automotive coolants and waste industrial glycol streams is vacuum distillation. Over 15 million gallons per year of total glycols are recovered by this technology, which are marketed for use in antifreeze and industrial chemicals. It is a robust technology, tolerant of many common feed contaminants, and producing minimum waste. This paper presents an overview of vacuum distillation as one part of a multistep process for recovering glycols from a wide variety of feedstreams. Described are industry practices for laboratory prescreening of feedstreams, process adjustments and pretreatments, distillation technologies and post-distillation polishing methods. In each section, information and data are presented from two independent facilities and for several streams processed at each facility. It is concluded that the facilities participating in this study can reliably produce ethylene glycol suitable for the production of ASTM specification engine coolants.
Development of Mobile, On-Site Engine Coolant Recycling Utilizing Reverse-Osmosis Technology
Authors: Kughn W , Eaton ER
Published: March 2009

This paper presents the history of the development of self-contained, mobile, high-volume, engine coolant recycling by reverse osmosis (R/O). It explains the motivations, created by government regulatory agencies, to minimize the liability of waste generators who produce waste engine coolant by providing an engine coolant recycling service at the customer's location. Recycling the used engine coolant at the point of origin minimizes the generators' exposure to documentation requirements, liability, and financial burdens by greatly reducing the volume of used coolant that must be hauled from the generator's property. It describes the inherent diffculties of recycling such a highly contaminated, inconsistent input stream, such as used engine coolant, by reverse osmosis. The paper reports how the difficulties were addressed, and documents the state of the art in mobile R/O technology. Reverse osmosis provides a purified intermediate fluid that is reinhibited for use in automotive cooling systems. The paper offers a review of experiences in various automotive applications, including light-duty, medium-duty and heavy-duty vehicles operating on many types of fuel. The authors conclude that mobile embodiments of R/O coolant recycling technology provide finished coolants that perform equivalently to new coolants as demonstrated by their ability to protect vehicles from freezing, corrosion damage, and other cooling system related problems.
Silicate Stabilization Studies in Propylene Glycol
Authors: Schwartz SA
Published: March 2009

In most North American and many European coolant formulations, the corrosion inhibition of heat-rejecting aluminum surfaces is provided by alkali metal silicates. But, their tendency towards polymerization, leading to gelation and/or precipitation, can reduce the effectiveness of a coolant. This paper presents the results of experiments which illustrate formulation-dependent behavior of inorganic silicate in propylene glycol compositions. Specific examples of the effects of glycol matrix, stabilizer type, and hard water on silicate stabilization are provided.
Overview of Engine Coolant Testing in Europe with Particular Regard to Its Development in Germany
Authors: Brösel MB
Published: March 2009

Many procedures exist worldwide to develop and to approve coolants for internal combustion engines. This paper discusses the aspects and types of coolant testing in general and the recent development of new test procedures in Europe. The work of the German coolant group is discussed in detail because they are completely revising the well known FVV Test R443/1986, which is the most important test for German car manufacturers.
Evaluation of Subsurface Modeling Application at CERCLA/RCRA Sites
Authors: Lee SB , Ravi V , Williams JR , Burden DS
Published: March 2009

Commonly observed aspects of ground-water model misuse are explored by reviewing twenty model application reports for CERCLA and RCRA sites. The observed aspects of misuse were categorized as: inadequate understanding of (1) the governing differential equations and the associated boundary and initial conditions, (2) conceptualization, (3) input parameter estimation and model calibration, (4) sensitivity and uncertainty analysis, (5) model selection and inherent model limitations, and (6) interpretation of modeling results. Among these identified categories, uncertainty in input parameter value estimation and insufficient sensitivity analysis were observed most frequently. The study results show a greater need for enhanced and continuing education in ground-water model application. It is recommended that stricter guidelines for quality control and quality assurance program for model application be developed. In addition, dissemination of the existing model guidelines should also be enhanced.
Reducing Modeling Uncertainty Using ASTM Ground-Water Modeling Standards
Authors: Brown DM
Published: March 2009

It is impossible to know with certainty that application of a ground-water modeling code to a site-specific problem is producing correct predictions. This paper describes procedures in ASTM standards that can reduce uncertainty associated with a model's predictive capability for use in decision-making. Modeling projects should begin with a clear statement of the objective. The modeler should consider restating the problem in terms of bounded predictions rather than specific numerical predictions to allow conservatism in assumptions. The modeler should develop a conceptual model of applicable hydrogeologic framework and physical processes. The uniqueness problem should be addressed by using measured hydraulic conductivities, calibrating to ground-water flow rates as well as hydraulic heads, and/or calibrating to data collected during multiple distinct hydrologic conditions. Over-calibration can be avoided by performing application verification. A sensitivity analysis should be performed to identify model inputs that meet the calibration criteria but produce fundamentally different predictions. A field audit can be performed to directly test the model's prediction. Sound hydrologic judgement is necessary to perform these procedures and interpret modeling results.
Conceptual Modeling of a Well-Developed Alluvial Basin
Authors: Williams D , Johnson NM , Fowler AC
Published: March 2009

The alluvial basin of northern Santa Clara Valley in central California has undergone extensive ground water development since early this century. Typical of many alluvial basins in the Western United States, the basin consists of coalesced fans deposits with little lateral continuity among individual sand and gravel zones.

The discontinuous lithology of Santa Clara Valley Basin, coupled with the sometimes minimalist lithologic logs provided by water well drillers, frustrate our attempts to use geology as a surrogate for defining the hydrostratigraphy and resultant model layers. Our alternative approach uses well completion data, supplemented by geologic data, to define depths of water-bearing zones. This method of defining hydrostratigraphy assumes that water well drillers typically recognize and successfully locate preferential depths for producing ground water.

We grouped well completion data from approximately 400 wells into basin subareas, based on general basin geology. Within each subarea, well screen abundance was graphed by depth. The screen-interval abundance graphs, supplemented with existing geologic interpretations, provided the basis of our hydrostratigraphic interpretation.

Screen-interval abundance suggested that the previously accepted three layer conceptual model of the Santa Clara Valley Basin could be divided into six hydrogeologic layers. We interpolated the six layers identified in each subarea to form basinwide layers, primarily based on ground water flow patterns and depth, with secondary consideration to geology. Geologic data and aquifer test data provided the basis for zoned hydrologic parameters in each layer. This method of estimating hydrostratigraphy, and subsequent model layers, results in a bias for placing well screens in individual model layers. This bias aids model calibration by associating historical water levels with individual model layers.

This six layer conceptual model provided a basis for a numerical flow model that successfully simulated ground water flow conditions in the Santa Clara Valley. Existing ground water maps showed important flow features that previous model attempts, incorporating simpler conceptual models, could not simulate. By reconciling the simpler conceptual models with our new conceptual model, we demonstrated that the important flow features were simulated, even though no single model layer reproduced the flow features observed on the existing ground water maps.
Verification Tests for Contaminant Transport Codes
Authors: Rowe RK , Nadarajah P
Published: March 2009

The importance of verifying contaminant transport codes and the techniques that may be used in this verification process are discussed. Commonly used contaminant transport codes are characterized as belonging to one of several types or classes of solution, such as analytic, finite layer, boundary element, finite difference and finite element. Both the level of approximation and the solution methodology should be verified for each contaminant transport code. One powerful method that may be used in contaminant transport code verification is cross-checking (benchmarking) with other codes. This technique is used to check the results of codes from one solution class with the results of codes from another solution class. In this paper cross-checking is performed for three classes of solution; these are, analytic, finite layer, and finite element.
Model Validation and Uncertainty Analysis — An Example Using a Nitrate Percolation Model
Authors: Mummert MC
Published: March 2009

Model validation and uncertainty analysis are demonstrated using a model previously developed for estimating nitrate-nitrogen (nitrate) concentrations in percolation water from land application of sewage sludge. The objectives are to demonstrate alternate validation techniques and to analyze uncertainty associated with model use following validation. Field data from three published sludge application studies and two separate methods are used for the validation. The first method, point validation, is accomplished by inserting mean values into the model to make point predictions. Model accuracy is then assessed by calculating coefficient of determination (r2), relative error and standard error. Statistical accuracy is tested using the Wilcoxon Signed Rank Test. The second method, statistical validation, uses Monte Carlo simulation to obtain distributions of model predictions. The hypothesis that field data represent reasonable samples from the distribution of model predictions is tested by checking whether observed values are within a range bounded by the 5 and 95 percent quantiles of the distribution. Both validation methods demonstrate that the land application model generally overestimates nitrate concentrations. Point validation provides quantitative values that can be compared with industry standard values for predictive models. Stochastic validation, on the other hand, allows uncertainty in model input to be considered during the validation process. Monte Carlo simulation is used to identify which model input parameters are the largest contributors to the uncertainty in model predictions. During successive simulations, individual random variables are set equal to their mean values. The decrease in the variance of model predictions is assumed to be the amount of uncertainty attributable to the random variable that had been set constant. This uncertainty analysis demonstrates that the rate of organic mineralization generally accounts for more than 50 percent of the uncertainty in model predictions.
Groundwater Modeling Using an Integrated Large-Capacity Finite-Element Model for Multiple Aquifer Groundwater Flow
Authors: Eddebbarh A , Carlson F , Hemker CJ
Published: March 2009

Groundwater computer codes have been used as a tool in a variety of ways in water resources planning, water rights evaluations, and groundwater contamination investigations and remediations. The use of groundwater models is burdened by the complexity of preparing the data input, evaluating model output, and difficulty in representing complex site physical features.

Micro-Fem is a software package composed of several integrated, well-defined parts and integrated programs. The software offers tremendous capabilities in terms of ease of data input preparation, checking the accuracy of the data, performing operations on the different model parameters, graphics display, and presentation and analysis of modeling results.

The Micro-Fem programs are developed to create and analyze a wide range of multilayer steady- and transient-state groundwater flow models with a maximum of 16 layers, 12,500 nodes, and 25,000 elements. The computer is used to replace the laborious finite-element administration and the file editing tasks by means of graphic screen control. The presentation of model results includes water balance calculations, flowlines, and travel time.

For the Centennial Water and Sanitation District (CWSD), groundwater is a key component in their water supply plans. Therefore, CWSD has undertaken a comprehensive groundwater modeling program to manage their groundwater resources.

The three main aquifers of the Denver Basin (Denver, Arapahoe, and Laramie-Fox Hills) developed by the CWSD were modeled using both Micro-Fem and the U.S. Geological Survey (USGS) finite-difference model, MODFLOW. Results of the two models were compared as well as the time required to prepare data and analyze modeling results. The comparison included model assessment of various scenarios of groundwater development. Also, the models were used to determine well development patterns that minimize water level declines and well replacement costs. Results of the comparison indicated that (1) Micro-Fem predicted heads were close to those predicted by MODFLOW, (2) Micro-Fem predicted pumping well cones of depression were similar to those predicted by MODFLOW, and (3) the time to prepare the input data and to display results was significantly lower than that required by MODFLOW.
Geostatistical Analysis of Hydraulic Conductivity of the Upper Santa Fe Group , Albuquerque Basin, New Mexico
Authors: Ruskauff GJ
Published: March 2009

A regional groundwater flow model has been developed to be used as a management tool for the Albuquerque Basin. It is crucial to recognize the impact of the inherent uncertainty in aquifer hydrogeology when applying the model, and an understanding of the effects of uncertainty can be accomplished using a probabilistic approach to address the role of natural variability of aquifer properties on management strategies.

Statistical analysis shows that the hydraulic conductivity data is moderately skewed to the right, but is not lognormal. Geostatistical analysis revealed zonal anisotropy oriented due north-south, which is directly related to the flow direction of the ancestral Rio Grande which laid down the Upper Santa Fe Group deposits. The presence of multiple depositional environments within the Upper Santa Fe Group violates the assumption of stationarity. This can be circumvented by choosing the simulation search radius so that local stationarity holds, or by separating the basin into two portions to be simulated separately and then combined for flow model analysis.
EIFS: Canadian Field Performance
Authors: Posey JB , Vlooswyk JA
Published: March 2009

Twenty-three installations of EIFS were investigated, located in central and western Canada. The installations ranged from 2 to 13 years old. Most were the soft coat type (Type PB). Each installation was visually examined for signs of distress or deterioration. In many cases, building owners, occupants, and managers were interviewed, the working drawings were examined, and the interior was inspected. In ten cases, representative samples of the insulation and finish were taken for laboratory analysis to determine lamina weight, thickness of finish and base coats, water absorption, polymer type and amount, and reinforcement. More than half of the installations were in good to excellent overall condition, although none were entirely free of defect. Approximately 30% had visible problems serious enough to threaten service life if left uncorrected. Ingress of moisture and impact damage were the most common causes of serious damage or deterioration. The project was funded by Canada Mortgage and Housing Corporation (CMHC) as part of an ongoing study of this exterior finish.
Reduced Tension Sealant Systems — EIFS Joint Design Properties and Lamina Stresses Initiating Substrate Failure
Authors: Baerveldt K
Published: March 2009

Canada Mortgage and Housing Corporation (CMHC) completed during 1994 a research program that investigated, amongst other aspects, joint design and sealant bond to EIF Systems. Eight different joint designs were tested as well as sealant bond strengths to the EIFS lamina (either finish or base coat). Polyurethane and silicone sealants as well as an impregnated expanding foam sealant composite were selected for testing based on the presumption of having either a “low modulus” characteristic, or of being representative of industry wide usage. Bond strength results indicated, that for the uniform samples tested, loads (stress) greater than 670 N (the cohesive strength of the EIFS lamina/EPS foam interface), will initiate substrate failure. Due to over-stressing of the EIFS lamina joint movement may occur without external visual signs. Capillaries or voids may be created either within the lamina or between basecoat and EPS foam that will effect short or long-term life expectancy. Of the joint design configurations tested, several could overly damage the EIFS lamina, even with limited movement. A series of joint designs has emerged based on either a binary sealant configuration or double joint with vented cavity (rain-screen principle) that show low lamina stress values. While these joints may not be fully pressure equalized rain-screen designs, the net effect is to prevent further moisture penetration into the EIF System.
EIFS Resistance to Water Penetration and Evaluation in Accordance with EIMA Test Method 101.02
Authors: Remmele TE
Published: March 2009

EIFS Resistance to water penetration has traditionally been measured in accordance with ASTM Standard Test Method for Resistance to Water Penetration of Windows, Curtain Walls, and Doors by Uniform Static Air Pressure Difference (E 331). EIMA modeled its standard test method for resistance to water penetration on E 331 with several modifications. This paper discusses the EIMA test method and results.
Functional Groups in the Avian Auditory System
Authors: Woolley Sarah M. N. , Gill Patrick R. , Fremouw Thane , Theunissen Frédéric E.
Published: March 2009

Auditory perception depends on the coding and organization of the information-bearing acoustic features of sounds by auditory neurons. We report here that auditory neurons can be classified into functional groups, each of which plays a specific role in extracting distinct complex sound features. We recorded the electrophysiological responses of single auditory neurons in the songbird midbrain and forebrain to conspecific song, measured their tuning by calculating spectrotemporal receptive fields (STRFs), and classified them using multiple cluster analysis methods. Based on STRF shape, cells clustered into functional groups that divided the space of acoustical features into regions that represent cues for the fundamental acoustic percepts of pitch, timbre, and rhythm. Four major groups were found in the midbrain, and five major groups were found in the forebrain. Comparing STRFs in midbrain and forebrain neurons suggested that both inheritance and emergence of tuning properties occur as information ascends the auditory processing stream.
Multiple Parietal Reach Regions in Humans: Cortical Representations for Visual and Proprioceptive Feedback during On-Line Reaching
Authors: Filimon Flavia , Nelson Jonathan D. , Huang Ruey-Song , Sereno Martin I.
Published: March 2009

Reaching toward a visual target involves at least two sources of information. One is the visual feedback from the hand as it approaches the target. Another is proprioception from the moving limb, which informs the brain of the location of the hand relative to the target even when the hand is not visible. Where these two sources of information are represented in the human brain is unknown. In the present study, we investigated the cortical representations for reaching with or without visual feedback from the moving hand, using functional magnetic resonance imaging. To identify reach-dominant areas, we compared reaching with saccades. Our results show that a reach-dominant region in the anterior precuneus (aPCu), extending into medial intraparietal sulcus, is equally active in visual and nonvisual reaching. A second region, at the superior end of the parieto-occipital sulcus (sPOS), is more active for visual than for nonvisual reaching. These results suggest that aPCu is a sensorimotor area whose sensory input is primarily proprioceptive, while sPOS is a visuomotor area that receives visual feedback during reaching. In addition to the precuneus, medial, anterior intraparietal, and superior parietal cortex were also activated during both visual and nonvisual reaching, with more anterior areas responding to hand movements only and more posterior areas responding to both hand and eye movements. Our results suggest that cortical networks for reaching are differentially activated depending on the sensory conditions during reaching. This indicates the involvement of multiple parietal reach regions in humans, rather than a single homogenous parietal reach region.
Spatiotemporal Dynamics of Perfusion and Oximetry during Ictal Discharges in the Rat Neocortex
Authors: Zhao Mingrui , Ma Hongtao , Suh Minah , Schwartz Theodore H.
Published: March 2009

Epileptic events elicit a large focal increase in cerebral blood flow (CBF) to perfuse metabolically active neurons in the focus. Conflicting data exists, however, on whether hemoglobin saturation increases or decreases in the focus and surrounding cortex, and whether CBF increases globally or is decreased in adjacent areas. How these hemodynamic events correlate with actual changes in tissue oxygenation is also not known. Using laser Doppler flowmetry, oxygen microsensors and intrinsic optical imaging spectroscopy, we demonstrate that the dip in hemoglobin in the focus correlates with a profound but temporary decrease in tissue oxygenation despite a large increase in CBF. Furthermore, CBF simultaneously decreases in the cortex immediately adjacent to the focus. These events are then replaced with a longer duration, less focal increase in CBF, cerebral blood volume, and hyperoxygenation, the duration of which correlates with the duration of the seizure. These findings raise the question of whether transient focal hypoxia and vascular steal might contribute to progressive deleterious effects of chronic epilepsy on the adult and developing brain. Possible mechanisms based on recent astrocyte-based models of neurovascular coupling are discussed.
Anticipatory Signatures of Voluntary Memory Suppression
Authors: Hanslmayr Simon , Leipold Philipp , Pastötter Bernhard , Bäuml Karl-Heinz
Published: March 2009

Voluntary memory suppression can keep unwanted memories from entering consciousness, inducing later forgetting of the information. In the present study, we searched for the existence of anticipatory processes, mediating such voluntary memory suppression. Using the think/no-think paradigm, subjects received a cue whether to prepare to think of a previously studied cue–target pair or whether to not let a previously studied cue–target pair enter consciousness. Examining event-related potentials, we identified two electrophysiological processes of voluntary memory suppression: (1) an early anticipatory process operating before the memory cue for a to-be-suppressed memory was provided, and (2) a later process operating after memory cue presentation. Both ERP effects were due to a decreased right frontal and left parietal positivity. They were positively related and predicted later forgetting. The results point to the existence of anticipatory processes, mediating voluntary memory suppression.
The GABRG2 Mutation, Q351X, Associated with Generalized Epilepsy with Febrile Seizures Plus, Has Both Loss of Function and Dominant-Negative Suppression
Authors: Kang Jing-Qiong , Shen Wangzhen , Macdonald Robert L.
Published: March 2009

The GABAAreceptor γ2 subunit mutation, Q351X, associated with generalized epilepsy with febrile seizures plus (GEFS+), created a loss of function with homozygous expression. However, heterozygous γ2(+/−) gene deletion mice are seizure free, suggesting that the loss of one GABRG2 allele alone in heterozygous patients may not be sufficient to produce epilepsy. Here we show that the mutant γ2 subunit was immature and retained in the endoplasmic reticulum (ER). With heterozygous coexpression of γ2S/γ2S(Q351X) subunits and α1 and β2 subunits, the trafficking deficient mutant γ2 subunit reduced trafficking of wild-type partnering subunits, which was not seen in the hemizygous gene deletion control. Consequently, the function of the heterozygous receptor channel was reduced to less than the hemizygous control and to less than half of the wild-type receptors with a full gene dose. Pulse-chase experiments demonstrated that in the presence of the mutant γ2S(Q351X) subunit, wild-type α1 subunits degraded more substantially within 1 h of translation. We showed that the basis for this dominant-negative effect on wild-type receptors was due to an interaction between mutant and wild-type subunits. The mutant subunit oligomerized with wild-type subunits and trapped them in the ER, subjecting them to glycosylation arrest and ER-associated degradation (ERAD) through the ubiquitin proteosome system. Thus, we hypothesize that a likely explanation for the GEFS+ phenotype is a dominant-negative suppression of wild-type receptors by the mutant γ2S subunit in combination with loss of mutant γ2S subunit protein function.
Altered Dendritic Spine Plasticity in Cocaine-Withdrawn Rats
Authors: Shen Hao-wei , Toda Shigenobu , Moussawi Khaled , Bouknight Ashley , Zahm Daniel S. , Kalivas Peter W.
Published: March 2009

Chronic cocaine treatment is associated with changes in dendritic spines in the nucleus accumbens, but it is unknown whether this neuroplasticity alters the effect of a subsequent cocaine injection on spine morphology and protein content. Three weeks after daily cocaine or saline administration, neurons in the accumbens were filled with the lipophilic dye, DiI. Although daily cocaine pretreatment did not alter spine density compared with daily saline, there was a shift from smaller to larger diameter spines. During the first 2 h after an acute cocaine challenge, a bidirectional change in spine head diameter and increase in spine density was measured in daily cocaine-pretreated animals. In contrast, no change in spine diameter or density was elicited by a cocaine challenge in daily saline animals during the first 2 h after injection. However, spine density was elevated at 6 h after a cocaine challenge in daily saline-pretreated animals. The time-dependent profile of proteins in the postsynaptic density subfraction elicited by a cocaine challenge in daily cocaine-pretreated subjects indicated that the changes in spine diameter and density were associated with a deteriorating actin cytoskeleton and a reduction in glutamate signaling-related proteins. Correspondingly, the amplitude of field potentials in accumbens evoked by stimulating prefrontal cortex was reduced for up to 6 h after acute cocaine in daily cocaine-withdrawn animals. These data indicate that daily cocaine pretreatment dysregulates dendritic spine plasticity elicited by a subsequent cocaine injection.
Role of Calcineurin Signaling in Membrane Potential-Regulated Maturation of Cerebellar Granule Cells
Authors: Okazawa Makoto , Abe Haruka , Katsukawa Michiko , Iijima Kouichirou , Kiwada Tatsuto , Nakanishi Shigetada
Published: March 2009

At the early postnatal period, cerebellar granule cells proliferate, differentiate, migrate, and finally form refined synaptic connections with mossy fibers. During this period, the resting membrane potential of immature granule cells is relatively depolarized, but it becomes hyperpolarized in mature cells. This investigation was conducted to examine the role of this alteration in membrane potential and its downstream signaling mechanism in development and maturation of granule cells. Experiments were designed to precisely characterize the ontogenic processes of developing granule cells by combining organotypic cerebellar cultures with the specific expression of EGFP (enhanced green fluorescent protein) in granule cells by use of DNA transfection. Multiple approaches using morphology, electrophysiology, and immunohistochemistry demonstrated that granule cells developed and matured at the physiological KCl concentration in organotypic cultures in a temporally regulated manner. We addressed how persistent membrane depolarization influences the developmental and maturation processes of granule cells by depolarizing organotypic cultures with high KCl. Depolarization preserved the developmental processes of granule cells up to the stage of formation of immature dendrites but prevented the maturation processes for synaptic formation by granule cells. Importantly, this blockade of the terminal maturation of granule cells was reversed by inactivation of calcineurin with its specific inhibitor. This investigation has demonstrated that alteration of the membrane potential and its downstream calcineurin signaling play a pivotal role in triggering the maturation program for the synaptic organization of postnatally developing granule cells.
Rapid quantification of Salmonella Typhimurium inoculated to meat products by real-time PCR
Authors: Cheng Ching-Yang , Chi Jing-Ruei , Lin Sin-Rong , Chou Chi-Chiang , Huang Chin-Cheng
Published: March 2009

The objective of this study was to use a 5′-nuclease (TaqMan) real-time PCR method with primers and probe specific to thespaQgene as a rapid approach to quantitatively determineSalmonellaTyphimurium. The result showed that the correlation coefficient between real-time PCR estimates and bovine serum albumin (BSA) plate counts ofS. Typhimurium was 0.99, independently of 105-fold numbers of bystanderEscherichia coliO157:H7 or total viable counts. The sensitivity of the real-time quantitative PCR assay was 10 CFU/mL for pureS. Typhimurium culture without enrichment. A known number ofS. Typhimurium target cells were inoculated to dumpling fillings and chicken nuggets and DNA was extracted for real-time PCR analysis. The sensitivity was 60 CFU/g forS. Typhimurium inoculated to the food samples without any preceding procedure of enrichment. The duration of the entire experiment from DNA isolation and purification to PCR amplification was less than 12 h. This study demonstrated that realtime PCR is a rapid and reliable technique for quantifyingS. Typhimurium possessing thespaQgene in pure culture and in meat products.