bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensing Glass Transitions in Thin Polymer Films on Acoustic Wave Microsensors
Authors: Grate JW
Published: March 2009

Acoustic wave microsensors are capable of sensing transition behaviors of homogeneous amorphous polymers applied as thin films to the surface of the sensor. The device and wave characteristics of four such microsensors, and examples of their uses in monitoring polymer properties, are described. The devices are the thickness-shear mode (TSM), surface acoustic wave (SAW), flexural plate wave (FPW), and shear horizontal acoustic plate mode (SH-APM) devices. Using the FPW device, the change in the polymer coefficient of thermal expansion at the static glass transition temperature is sensed as a change in slope of the frequency-temperature plot. This behavior reflects the fact that the frequency measures acoustic velocity, which decreases as the polymer modulus decreases. Modulus decreases as the polymer volume increases. Frequency-dependent relaxation properties are detected with a sigmoidal change in slope of the frequency-temperature plot and a minimum in signal amplitude. The minimum in signal amplitude is analogous to the maximum in the loss tangent in dynamic mechanical analysis, or the maximum in sound damping in bulk-wave ultrasonic studies.
Plasticization of Polystyrene by High Pressure Gases: A Calorimetric Study
Authors: O'Neill ML , Handa YP
Published: March 2009

A Tian-Calvet type heat-flow calorimeter has been modified for use at pressures up to 400 bar, and has been used for studying the glass transitions in the systems polystyrene (PS)-methane (CH4), -ethylene (C2H4), and -carbon dioxide (CO2). All three gases plasticize PS leading to lowering of the glass transition temperature Tg. The low-solubility gas CH4 induces somewhat weak plasticization; the Tg decreases gradually, with a dTg/dP value of about — 0.2 K bar-1, for pressures up to 150 bar after which the Tg remains almost constant for pressures up to 350 bar. At higher gas pressures, CH4 acts more like a hydrostatic-pressure generator than as a plasticizer such that the hydrostatic effect, which tends to raise the Tg, cancels out any additional plasticization effect. The moderately soluble gases, C2H4 and CO2, show rather strong plasticization effects with a dTg/dP value of about — 0.9 K bar-1 for both gases. The highest pressures at which the glass transition in the two-phase polymer-gas systems PS-C2H4 and PS-CO2 could be measured were 88.0 and 60. 0 bar, respectively. For the PS-CO2 system where gas solubility data are available, the measured Tg's agree very well with the values calculated from the model proposed by Chow [25].
Glass Transition(s) of Ionomers
Authors: Weiss RA
Published: March 2009

Ionomers are predominantly nonpolar polymers that contain a small amount of bonded salt groups. Microphase separation of ion-rich microdomains occurs as a consequence of the thermodynamic incompatibility of the salt groups and the polymer matrix and associative interactions between salt groups. Associations of the salt groups usually increase the glass transition of the continuous matrix phase, presumably as a consequence of the inhibition of chain mobility that accompanies physical crosslinking. The central question raised in this paper is whether the dispersed ion-rich microphase exhibits a glass transition. Although no glass transition for the microphase is detected by calorimetry, a dynamic mechanical relaxation is commonly observed above the Tg of the matrix phase. This transition has some of the attributes of a glass transition, but it is not clear what is the actual relaxation process that is measured. This paper discusses the effect of the ionic groups on the matrix glass transition, the origin of the high-temperature dynamic mechanical transition, and the effects of the addition of plasticizers on the Tg of the matrix and the higher temperature mechanical relaxation.
The Glass Transition Temperature of Glassy Polymers Using Dynamic Mechanical Analysis
Authors: Rodriguez EL
Published: March 2009

Dynamic Mechanical Analysis (DMA) is presented for four glassy polymers. Poly(vinyl acetate), poly(vinyl chloride), poly(styrene), and poly(carbonate) were studied as a function of the heating rate using ramp and step heating programs and a constant frequency of 1 Hz. The effect of frequency on the dynamic mechanical parameters was also examined from 0.01 Hz to 10 Hz. The dynamic elastic storage modulus (E'), the dynamic elastic loss modulus (E'') and the tanδ (E"/E') were affected by both the heating rate and the frequency. Apparent activation energies for the glass transition were also determined for the four polymers which were in the range from 98 of 194 kcal/mol.
Measuring the Glass Transition Temperature of EPDM Roofing Materials: Comparison of DMA, TMA, and DSC Techniques
Authors: Paroli RM , Penn J
Published: March 2009

Two ethylene-propylene-diene monomer (EPDM) roofing membranes were aged at 100°C for 7 and 28 days. The Tg of these membranes was then determined by dynamic mechanical analysis (DMA), thermomechanical analysis (TMA), and differential scanning calorimetry (DSC) and the results compared. It was found that: (1) Tg data can be obtained easily using the DMA and TMA techniques. The DSC method requires greater care due to the broad step change in the baseline which is associated with heavily plasticized materials. (2) The closest correspondence between techniques was for TMA and DSC (half-height). The latter, within experimental error, yielded the same glass transition temperature before and after heat-aging. (3) The peak maxima associated with tanδ and E“ measurements should be cited with Tg values as significant differences can exist. (4) The Tg(E") values were closer to the Tg(TMA) and Tg(DSC) data than were the Tg(tanδ) values. Data obtained at 1 Hz (or possibly less) should be used when making comparisons based on various techniques. An assessment of Tg values indicated that EPDM 112 roofing membrane is more stable than the EPDM 111 membrane. The Tg for EPDM 112 did not change significantly with heat-aging for 28 days at 130°C.
Evaluation of Upper Use Temperature of Toughened Epoxy Composites
Authors: Jankowsky JL , Wong DG , DiBerardino MF , Cochran RC
Published: March 2009

Traditionally, the glass transition temperature (Tg), as determined by thermal analysis, has been used to calculate the material use threshold. The main drawback to the use of Tg as a measure of upper use temperatures is that it results in use temperatures that are significantly higher than the use temperatures developed through mechanical testing. This study compared operating limits obtained from mechanical tests to glass transition temperatures obtained by several methods of thermal analysis.

A toughened epoxy composite, IM7/977-3 from ICI Fiberite, was tested in this study, along with the corresponding neat resin. The mechanical tests performed were interlaminar shear, resin compression, and material operating limit (MOL) testing (a modified open-hole compression test). Specimens were tested over a range of temperatures to determine the upper use temperature.

Thermal analysis testing included differential scanning calorimetry (DSC) and thermal mechanical analysis (TMA). Two types of dynamic mechanical spectroscopy (DMS) tests were performed: dynamic mechanical analysis (DMA) and Rheometrics dynamic analysis (RDA). The effects of moisture, heating rates, and test frequency on the measured Tg were examined.

The DMS tests were found to give more reproducible results than either the DSC or TMA. Higher heating rates and test frequencies resulted in higher measured Tg's. Shift factors were developed to allow comparison between data obtained at various heating rates and tests frequencies. Results from the mechanical testing corresponded more closely to the storage modulus measurements of the DMS tests than the values obtained from the tan delta curves.
Gait Dynamics with Step Height Alterations
Authors: Schieb DA
Published: March 2009

Walking ground reaction forces (GRF) were recorded from a quartz force plate, whose surface was positioned above, below, and level with respect to a level walkway grade. Significant differences in selected GRF measures were found between the level condition and step-up heights >25 mm and step-down heights >-14.7 mm. No differences were found between the level condition and a step-up height of 6.7 mm. Implications were discussed regarding alterations in gait dynamics, and suggestions were provided regarding additions of suprastructures to quartz force plates.
Slip Resistance Needs of the Mobility Disabled During Level and Grade Walking
Authors: Buczek FL , Cavanagh PR , Kulakowski BT , Pradhan P
Published: March 2009

Slip resistance needs were compared between mobility disabled and able-bodied individuals. Subjects walked across a level piezoelectric force plate at slow and fast speeds, and the ratio of the total shear force to the normal force was used as the required coefficient of friction (μr) Near touchdown,μr was found to be significantly greater (p < 0.05 for all significance values) for the mobility disabled (0.64 ± 0.19) than for the able-bodied (0.31 ± 0.07), regardless of the speed of walking. In contrast, slip resistance needs for these two groups were not different near push-off (disabled and able-bodied were each 0.41 ±0.17), although for both groups walking fast required significantly greater slip resistance (0.48 ± 0.19) than walking slow (0.34 ± 0.11). Required coefficient of friction was also calculated as disabled subjects walked up and down a ramp of 1:12 grade. At touchdown, no significant differences among the mean μr values were found for level, uphill, and downhill walking at slow or fast speeds. At push-off, slow-speed walking uphill required significantly greater slip resistance (0.46 ± 0.20) than level (0.34 ± 0.14) or downhill (0.34 ± 0.17) walking. No difference was found among the three grades for the fast speed. It was concluded that the mobility disabled do require greater slip resistance than the able-bodied, and that this puts them at increased risk for falling.
Improved Tribometry on Walking Surfaces
Authors: English W
Published: March 2009

In an effort to bring practical tribometry closer to a standard floor traction tester, improvements to the Horizontal Pull Slipmeter (HPS) designed to overcome major objections to its adoption as a standard testing device are discussed. There is a need for a standard test method for evaluating slipperiness of walking surfaces that are wet or contaminated with other lubricants in a wide variety of environments. Portability and utility on actual walkway surfaces under a wide range of environmental conditions are as important as precision and consistence in practical tribometric devices. The validity and practical limitations in the use of traditional coefficient of friction testing appliances are discussed in comparison with the improved HPS.
Forensic Engineers Look at Slip and Fall Accident Investigations
Authors: McNeill JG
Published: March 2009

A forensic engineering investigation of slip and fall accidents has its own unique set of problems and trends. The National Academy of Forensic Engineers (NAFE) conducted a Slip and Fall Accident Workshop on 27 July 1989 in Minneapolis, Minnesota. The function of the Workshop was to bring together experienced speakers and NAFE participants to hear presentations on slip and fall subjects and then to exchange comments and to discuss local forensic investigation and reporting practices.

The Workshop was concerned with presenting an understanding of the mechanics of walking and falling; the techniques of forensic investigations and reporting; the available means of measurement and testing of the accident site; the codes, standards, and reference sources; the law of slip and fall; written and oral discovery procedures; and the trial process. Each participant brought examples of their reports and prepared a listing of the problems and trends in their slip and fall practice.

The purpose of this paper is to review the results of the Workshop discussions by listing the slip and fall forensic problems, trends, and reporting practices. From this discussion came a list of recommendations for the forensic engineer.
Development of SATRA Slip Test and Tread Pattern Design Guidelines
Authors: Wilson MP
Published: March 2009

Measurement of dynamic friction at a sliding speed of approximately 10 cm/s has been found to correlate more closely with slip resistance, as assessed in wear tests, than measurement of either static friction or high speed dynamic friction (1.5 m/s) or both. A new friction test for footwear and floorings is described which measures dynamic friction at 10 cm/s under conditions simulating those in walking when slip occurs.

Three areas of application of the test are discussed: (a) Development of standards for slip-resistance testing: the SATRA Friction Test conforms to a proposed ISO Safety Footwear test method recently drafted; (b) Development of sole tread pattern design guideline; good shoe sole design is important in achieving slip resistance on lubricated or contaminated surfaces. The effective characteristics of tread pattern design have been investigated and the findings are summarized in a set of sole design guidelines. (c) Product development: progress in developing new heel top-piece materials for women's shoes having improved slip-resistance is reported.
Assessing the Slip Resistance of Flooring Materials
Authors: James DI
Published: March 2009

A standard rubber for assessing slip resistance is specified and recommended. This Standard Simulated Shoe Sole (Four S rubber) is available from Rapra Technology Limited. When it is used in the British Portable Pendulum Test it gives increased sensitivity on smooth floors in wet conditions. This rubber is additional to that used for measuring the skid resistance of roads and exterior paved areas.

A new approach to slip resistance measurement is suggested. In a prototype apparatus, it is arranged that the normal load diminishes as a sled is propelled by a constant force. The time taken for the sled to travel a set distance then gives a measure of the slip resistance of the surface. Fractional force and velocity both change during measurement in a manner thought to be similar to the changing parameters in a slipping accident. The measured time is related to the reaction time of the person who slips, making it possible to allow for age, infirmity, or other impairment. A few preliminary results are given, but no comparison with other tests has yet been made.
Irradiated Dynamic and Arrest Fracture Toughness Compared to Lower-Bound Predictions
Authors: Server WL , Mager TR
Published: March 2009

Pressure-temperature operating curves for nuclear reactor pressure vessels are based upon a lower-bound fracture toughness curve which bounds rapid load dynamic initiation and crack arrest fracture toughness data. The ASME Boiler and Pressure Vessel Code defines the reference toughness (KIR) curve as this lower bound, and this KIR curve was developed solely from unirradiated dynamic and arrest fracture toughness data from one heat of SA533B-1 steel (HSST Plate 02) and two heats of SA508-2 steel. The effects of radiation embrittlement on the shape and shift of the KIR curve to account for the increase in reference temperature is thought to be conservative, but this conservatism has not been fully verified. This study reviews available data from past dynamic and arrest toughness tests on irradiated vessel steels from test reactor irradiations and compares the data to the shifted KIR curve using the transition temperature shift approach detailed in Regulatory Guide 1.99, Revision 2. Dynamic initiation and crack arrest fracture toughness data are available from only a few irradiated large specimen tests (that is, test specimens with thicknesses greater than about 51 mm [2 in.]); small specimen tests (including precracked Charpy) are used for the other comparisons. The limited results indicate that the Regulatory approach for shifting the KIR curve is very conservative even when the Regulatory Guide 1.99, Revision 2 “margin term” is not used and a correction for fluence rate is ignored. No change in shape for the dynamic toughness and arrest data (in particular for low upper shelf materials) was observed.
Using Small Specimens to Measure Dynamic Fracture Properties of High-Toughness Steels
Authors: Conque H , Dexter RJ , Hudak SJ
Published: March 2009

The use of coupled pressure bars (CPB) to induce dynamic fracture in tough materials using small specimens is investigated. CPB experiments were performed with a nuclear pressure vessel steel, A533 Grade B Class 1, over the temperature range 37 to 100°C. The dynamic fracture initiation toughness at a stress intensity loading rate, KI, of 2 × 106 MPa∙m½ s−1 was deduced from the simulation of the fracture experiment with a dynamic viscoplastic finite-element fracture code. At 100°C, no cleavage fracture was observed for either dynamic crack initiation or subsequent propagation and arrest. A procedure to measure initiation, propagation, and arrest toughnesses of nuclear pressure vessel steels up to service temperature with CPB specimens is introduced.
Fracture Resistance of a Pressure Vessel Steel Under Impact Loading Conditions
Authors: Böhme W
Published: March 2009

Impact experiments were performed with Charpy specimens and with large bend specimens made from a ferritic pressure vessel steel. All specimens were side-grooved and fatigue-precracked. Different amounts of ductile crack extension up to 16 mm were achieved by varying the available impact energy. The measured hammer load signals were evaluated to calculate J integral values.

The determined dynamic J-resistance curves of the bend specimens are significantly above the Charpy data. Examinations of the fracture surfaces and metallographic sectioning perpendicular to the crack front showed that behind the stretched zone the ductile main crack is accompanied by side cracks with a length up to about 3 mm for the large specimens, whereas such side cracks are hardly found in Charpy specimens. The additional energy needed for the formation of side cracks might explain higher J-resistance curves for larger specimens.

Further results indicate that with increasing loading rate and specimen size the tendency to develop side cracks increases in correlation with higher J-resistance curves. Finally, an attempt is made to discuss the relevance of this effect for the behavior of components.
Dynamic Crack-Tip Opening Displacement (CTOD) Measurements with Application to Fracture Toughness Testing
Authors: Tregoning RL , Shapiro JM , Sharpe WN
Published: March 2009

Crack-tip opening displacement (CTOD) measurements were made 100 üm behind the crack tip on standard three-point bend specimens using a laser-based interferometric technique. Four materials (SAE-01 steel, 4340 steel, HY-100 steel, and tungsten) were tested at loading rates ranging from quasi-static (K ≈ 1 MPa∙ m½/s) to dynamic (K ≈ 106 MPa ∙ m½/s).

The quasi-static and intermediate rate tests and analyses were conducted according to the guidelines specified in ASTM Test for Plane-Strain Fracture Toughness of Metallic Materials (E 399). In these lower rate tests, load was applied by a servohydraulic testing machine and a clip gage was used to record the crack-mouth opening displacement (CMOD). From these data, the stress intensity factor, K, and the fracture toughness can easily be determined from the standard methodology.

In the high rate tests, inertial effects are prevalent and K is not as easily measured. The initial measurements of CTOD, however, can be used to provide a calibration between the static and dynamic tests if K is assumed to increase linearly with time during the 10 to 15 μs before the crack starts to propagate. If this assumption holds, dynamic time-CTOD results can be converted to K-CTOD curves using a companion specimen technique. Further, the dynamic fracture toughness can then be found by superimposing static and dynamic K-CTOD results and employing a reduced slope technique to locate the onset of crack propagation.

This dynamic technique has been modeled after existing practices defined in ASTM Test E 399 and leads to experimental scatter comparable to that found in static fracture-toughness tests. The results show that there is no dramatic change in the fracture toughness over this range of loading rates for any of the materials studied.
A New Method to Test Crack-Arrest Toughness by Using Three-Point Bend Specimens
Authors: Varga T , Schneeweiss G
Published: March 2009

This paper demonstrates the applicability of small and simple specimens to measure crack-arrest toughness, KIa. Specimens used up to now were large or of complicated geometry. Using small instrumented three-point bend specimens of simple geometry, possibilities and limitations were investigated. KIa values measured on compact crack arrest specimens and, respectively, by using three-point bend specimens have been compared. The results of such investigations on steel A 533 grade B class 1 are shown.
Lime Used for Precipitated Calcium Carbonate (PCC) for the Paper Industry
Authors: Clark EB
Published: March 2009

Various factors in the paper marketplace are catalyzing an accelerating trend toward alkaline papermaking technology. These factors include the development of synthetic sizing (water penetration resistance) chemicals, the on-site precipitated calcium carbonate (PCC) plant concept, functional improvements in process control chemicals, a decrease in the availability and corresponding increase in the cost of high quality wood fiber and key mineral fillers, and heightened customer sensitivity to paper permanence (storage longevity). The total lime required for manufacturing PCC to be used by the paper industry in fine papers in 1994 is forecast to be 1 430 000 metric tons.
Comparison of In-Situ Resilient Moduli of Aggregate Base Courses With and Without Low Percentages of Lime Stabilization
Authors: Little DN
Published: March 2009

Six pavement sections were tested using a falling weight deflectometer (FWD). The six pavement sections were all in the Phoenix, AZ area. All six pavements have the same pavement structural cross-section: 3 to 4 in. (76.200–101.60 mm) of hot mix asphalt concrete surface supported by 10 to 13 in. (254.00–330.20 mm) of aggregate base course and underlain by a granular subgrade. Three of the six pavements possess aggregate base courses which have been stabilized with 1 % hydrated lime. The other three pavements incorporate the same aggregate base course but without lime stabilization.

Resilient moduli of all pavement layers were back-calculated based on the FWD data. The moduli of all pavement layers are analyzed statistically. The addition of the same percentage of lime is shown to make a substantial difference in the stiffness of the layers and the structural contribution of the base layer to the pavement system. The effect of the stabilization with small percentages of lime on pavement performance and pavement life is discussed.
Calcium Hydroxide Treatment of Construction Aggregates for Improved Cementation Properties
Authors: Graves RE , Eades JL , Smith LL
Published: March 2009

Laboratory studies have shown beneficial effects from calcium hydroxide (Ca(OH)2) treatment of crushed aggregate materials commonly utilized in construction. Two contrasting cementation systems were investigated which demonstrate how Ca(OH)2 treatment of aggregates may be effectively used to improve the cementing properties of construction materials.

Highway base course materials composed of crushed limestone aggregates have been observed to increase in strength with time after compaction and is thought to be due to natural carbonate cementation processes. Addition of Ca(OH)2 to crushed limestone base course materials before compaction caused significant increases in laboratory bearing strength values after continuous soaking in water. It is believed this is due to carbonation of the Ca2+ ions, producing additional calcium carbonate cementation of the particles. The amount of strength developed is a function of calcite/quartz ratios for the compacted materials. Scanning electron microscope (SEM) investigations suggest this is due to the better bonding properties of carbonate cement-carbonate particle systems versus carbonate cement-silicate particle systems.

In portland cement concrete, carbonate aggregates appear to react chemically with the cement hydration products, forming a good interfacial bond. In contrast, cracks are often more prominent at the cement paste-silicate aggregate interface, suggesting this is a weak link in both strength and durability of concrete. Treatment of crushed granite aggregates with a Ca(OH)2 solution, followed by the subsequent drying of the aggregates, resulted in increased compressive strength for 28 day moist cured portland cement concrete mixes. SEM studies of concrete prepared with untreated and treated granite aggregates suggest this is due to improved interfacial bonding between the cement paste and treated granite aggregates. The proposed mechanism for improved bonding is disruption of the hydrated silicate surface by drying, allowing for stronger adsorption of Ca2+ ions onto negative charge sites. This appears to provide a bridging mechanism for bonding cement hydration products to the silicate aggregate surface.
High Surface Area Hydrate—WUELFRAsorp®—Commercial Production and Application
Authors: Schwarzkopf F , Hennecke HP , Roeder A
Published: March 2009

Hydrated lime is an important chemical and sorbent for the removal of sulfur dioxide (SO2), hydrochloric acid (HCl) and hydrofluoric acid (HF) from waste gases of utility and industrial boilers, municipal and industrial waste incinerators, and aluminum and glass melting furnaces. Commercially produced conventional hydrates normally have specific surface areas of 15 to 17 m2/g. Using water-alcohol mixtures for hydration, specific surface areas of 40 m2/g and higher are achieved. Rheinische Kalksteinwerke GmbH, Wuelfrath, Federal Republic of Germany (FRG), developed and patented a commercial process for the manufacture of high surface area hydrate (WUELFRAsorp®) and, since early 1989, operates a six metric tons per hour (TPH) plant, providing sorbent to several flue gas cleaning installations. The manufacturing steps in the commercial plant are described and results of industrial applications are given.
Environmental Effect on a Thermoplastic Elastomer (TPE) for Use in a Composite Intervertebral Disc Spacer
Authors: Hawkins MV , Zimmerman MC , Parsons JR , Langrana NA , Lee CK
Published: March 2009

Four durometers of a modified copolymer of styrene-ethylene/butylene-sty-rene were evaluated after in-vitro exposure to saline at 37°C (3, 6, 9, or 12 months) or in-vivo subcutaneous implantation (3 months). Specimens were evaluated for changes in mass, chemistry, and mechanical behavior. In-vitro exposure resulted in minimal moisture uptake by all durometers, no chemical alterations in any durometer, and slightly increased stiffness of the 90A durometer. All changes occurred within the first three months. In-vivo exposure resulted in a greater increase in mass, particularly of the 70A durometer. Chemical alteration in the form of an exaggerated carbonyl was observed in the 70A durometer only. These changes are indicative of possible lipid absorption. Mechanical changes included decreased stiffness of the 35A and 50A durometers, increased stiffness of the 90A durometer, and no change in the 70A durometer. These changes do not reflect the physical and chemical changes and are attributed to a balance between lipid and fluid absorption along with possible absorption of biological antiplasticizing agents or mineral oil leaching, or both.
In Vitro Studies on the Electrochemical Behavior of Carbon-Fiber Composites
Authors: Kovacs P
Published: March 2009

Using potentiodynamic polarization and electrochemical impedance techniques, the electrochemical behavior of carbon-fiber/polyetheretherketone (C/PEEK) composite material was studied primarily in lactated Ringer's solution with and without a stable, fast reacting redox couple (0.01M K4[Fe(CN)6] + 0.01M K3[Fe(CN)6]), at 37°C. For comparison, the spontaneous passivation of stainless steel 316L, Co-Cr-Mo alloy, and Ti-6Al-4V was also investigated in these electrolytes. It was found that the rate of total electrochemical interaction (corrosion + electron exchange) between a spontaneously passivated metal and the environment can be considerably smaller than the rate of simple electron exchange between the carbon-fiber composite and the environment. Considering the excellent biocompatibility of carbon, this finding seems to indicate the important role of protective passive films on metals, rather than the clinical significance of higher electron exchange rates in general. When the protective passive layer on the metals is damaged or removed mechanically, the undesirable effect of substantially increased corrosion rates can be observed, particularly in environments with low redox activity. While galvanic corrosion may also occur between the mechanically depassivated and the passive sites of implant metal surfaces, more considerable galvanic corrosion can be expected if the metal undergoing fretting wear is in contact with a carbon-fiber composite, depending on the anodic/cathodic surface area ratio and on the redox properties of the environment. Additionally, the repassivation of the damaged metal surface may not take place effectively. Being the most susceptible to localized corrosion, stainless steel 316L, even in the passivated condition, may show accelrated pitting corrosion if coupled with carbon-fiber composites.
The Effect of Interfacial Bonding Upon Compressive Strength and Fracture Energy of Carbon Fiber Reinforced Polymer (CFRP) Composite: A Theoretical Investigation
Authors: Latour RA , Zhang G
Published: March 2009

Under compression, polyacrylonitrile (PAN) based carbon fiber reinforced polymer (CFRP) composites fail by fiber microbuckling. The compressive strength of CFRP is known to be dependent upon the properties of the matrix and the fiber/matrix interfacial bond. Two-dimensional analytical models can not properly model interfacial stress distributions to address this relationship. An approximate three-dimensional micromechanics model for compressive behavior has therefore been developed and applied to carbon fiber/polysulfone and carbon fiber/polyetheretherketone (CF/PEEK) composites to predict the composite component responsible for initiating compressive failure, and the dependence of theoretical compressive strength and fracture energy upon interfacial bond strength. Results indicate that interfacial debonding or matrix shear yielding will occur well before fiber fracture and will thus be the initiator of fiber microbuckling instability, underscoring the importance of high interfacial bond strength and environmental resistance for the development of CFRP composite for structural orthopaedic implant applications. Design concepts for maximizing CFRP implant compressive strength and fracture energy are proposed.
A Life Prediction Model for Fatigue Loaded Composite Femoral Prosthesis
Authors: Liao K , Reifsnider KL
Published: March 2009

A life prediction model for fatigue loaded femoral prosthesis made from fiber-reinforced composite materials is presented. The model is developed based on a strength of materials approach/classical laminate analysis, and a critical element model, where biaxial mechanical and environmental loadings are taken into consideration. The model is shown to be capable of predicting the remaining strength and life of a composite femoral prosthesis.
Intraoperative Impact: Characterization and Laboratory Simulation on Composite Hip prostheses
Authors: Maharaj GR , Jamison RD
Published: March 2009

Impact force measurements and energy calculations were performed on five embalmed cadaveric femora and an intact cadaver undergoing composite hip stem insertion using standard surgical methods. In addition, the number of impacts required to fully seat each stem was recorded.

The mean hammer velocity at the instant of impact was 5.15 ± 0.14 m/s and six impacts were required to fully seat the stem in all cases. The mean impact force was 6.20 ± 0.15 kN for the isolated femurs and 5.83 ± 0.67 kN for the cadaver. The mean impact energy was calculated to be 4.50 ± 0.54 J for the isolated femurs and 4.55 ± 0.43 J for the cadaver. Microscopic examination of the stems revealed no evidence of surface damage in any of the tests.

The forces and energies associated with intraoperative impact as measured in this study are sufficiently large to be of concern when considering the introduction of composite materials as replacements for metals in hip femoral components. Impact testing should be woven into the test scheme for both candidate composite materials and for different hip designs using these materials.
Characterization and Optimization of Small Particle Dental Composites
Authors: Vaidyanathan TK , Vaidyanathan J , Waknine S
Published: March 2009

The properties of commercial and experimental small particle dental composite formulations and selected unfilled resins have been evaluated in a systematic way. The unfilled resins were evaluated for percent conversion, molar heat of cure and microhardness as a function of resin composition, and ambient temperature of cure. The results show that the ambient temperature and resin composition may significantly influence these properties. Moderately higher ambient temperature of cure in the range 40 to 60°C and proper resin selection was found to significantly improve the resin properties studied. The diametral tensile strength, top hardness, bottom hardness, thermal expansion (TE) coefficient, watersorption (WS), and average surface roughness of composite resins were also evaluated as a function of filler particle size (PS) and volume fraction (VF) in a series of experimental composites and in selected commercial systems. The results show a dominant contribution of filler VF to all the composite properties and additional significant PS and VF-PS interactive effects in some composite properties.
A Survey of Practicing Anesthesiologists on Auditory Alarms in the Operating Room
Authors: Griffith RL , Raciot BM
Published: March 2009

Electronic monitoring equipment appears to have advanced measurably the safety of anesthesia care by extending the human senses of the anesthetist beyond his native sight, touch, smell, and hearing. Yet electronic vigilance of an anesthetized patient is effective only when information receives the attention of the anesthetist for analysis and action. Auditory signaling has been used commonly to alert the anesthetist to unusual measurements made by a monitoring device. While there is general acceptance that auditory signaling or auditory alarms may be suboptimal in the operating room, there may not be sufficient quantification of the acceptability of alarms for rational selection of remedies.

Five hundred anesthesiologists in active practice in the United States of America were selected at random from the directory of the American Society of Anesthesiologists. A letter and a questionnaire were mailed to each anesthesiologist with a stamped envelope to facilitate a reply. The number of responses and the frequency of comments indicates a high degree of interest in the issue of operating room alarms. Alarms appear to be viewed as a contributor to stress in the operating room. Anesthesiologists want their alarms to be clearly different than alarms on other equipment in the operating suite. There appears to be good support for distinctive alarm sounds, graded alarms, and intermittent alarms, although there are differences in opinion on the optimal type of alarm between voice, central displays, or distinctive tones.
The Man/Machine Interface in the Operating Room: An Ergonomic Approach to a Rational Alarm System
Authors: Blum LL
Published: March 2009

We discuss the ergonomics of the man/machine interface in relation to the administration of an anesthetic. We describe the cognitive activities of the anesthesiologist, the limitations of attention, and its effect on patient monitoring. We propose the use of a device which notifies only the anesthesiologist of an alarm message, without disturbing the patient or otherwise interfering with the routine of the operating room. A visual monitor placed next to the patient can centralize and coordinate all alarm signals, thereby improving patient safety.
Intelligent Monitoring and Symbolic Representation of Clinical Knowledge: An Application in Acute Ventilatory Management
Authors: Moret-Bonillo V , Alonso-Betanzos A , Truemper EJ , Searle JR
Published: March 2009

Patient monitoring in intensive care units (ICUs) is a difficult task. This is due, in part, to the important role that the dynamic and static contexts play in the interpretation of the measurements. Classical approaches dealing with this problem usually consist of: (a) building systems for massive acquisition of data and display of the information, and (b) building expert systems. In the first approach the data are not interpreted. In the second approach the use of heuristic techniques is useful to obtain conclusions based on the analysis of the information already available. These conclusions, however, do not take into account the particular characteristics of the patient under consideration. In other words, these systems do not include “common sense” either for interpreting measurements or to prescribe therapies. In this paper we explain the nature of a different procedure, in which a patient-oriented symbolic approach is followed in order to define some particular circumstances that may modify the criteria for the interpretation of the corresponding variables. These interpretations are adapted to the particular case under consideration. The approach is illustrated with an application in acute ventilatory management.
Problems in Designing Studies for Pharmaceutical Development: Patients, Prescriptions, and Physicians
Authors: Fishken D
Published: March 2009

More palatable pharmaceuticals mean easier administration, better compliance with prescription requirements, and less unpleasantness associated with illness. Developing the best possible taste, smell and texture for a pharmaceutical product requires the presence of the active ingredient; its taste or smell has to be masked or mitigated. With an active ingredient present, the respondent must be a “patient,” someone who uses this product when needed.

Some of the factors that determine the research design are: (1) the status of the product, is it “over the counter” (OTC) or prescription, and (2) the need to conduct tests among symptomatic patients versus asymptomatic individuals. In the case of OTC products, research designs must often be submitted to an Institutional Review Board (IRB), so that an independent group of specialists, including a physician, can determine that the project is conducted in an ethical manner. IRBs are required when nonphysicians administer pharmaceuticals. In the case of prescription drugs, physicians must be employed to place products with their patients when illness calls for the particular drug under investigation.

With regard to the presence or absence of symptoms, consider that tests of liquid cold remedies or nasal decongestants require symptomatic individuals since sensory acuities are altered by nasal decongestion. On the other hand, antacid tests do not require the presence of symptoms when the issues are taste and texture.

Case studies are presented to demonstrate the complexities of sensory research for OTC and prescription products.
A Comparison of Acceptability Scaling Methods for Use with Children
Authors: Spaeth EE , Chambers E , Schwenke JR
Published: March 2009

Few studies concerning product testing by children have been published. Authors have previously suggested the use of verbal or facial scales to measure product acceptability with children. In a previous test comparing scales, one author concluded that a nine-point scale was marginally better than a seven-point scale. Verbal scales were slightly more discriminating for acceptability than the facial scale. In this study, the three-, five-, and nine-point lengths were tested as verbal, facial, and end-anchored box scales. Three different commercially available beverages were presented to the children. Results indicated that most scales could discriminate acceptability among the beverages. No one type or length of scale appeared to be more advantageous. Apparently, children do not use the facial scales or the short scales better than other scales and, therefore, do not need special scaling techniques.
The Evaluation of a Health and Beauty Aid Product by a Hispanic Population: A Case Study by Client and Supplier
Authors: Wong M , Beckley JH , Schraidt MF
Published: March 2009

Traditional procedures for marketing research need to be reviewed when working with a specialized population. This study's Hispanic test group is distinct from the typical population and diverse internally, with societal and attitudinal idiosyncrasies as well as differing language and cultural backgrounds, that can hamper the execution of basic methodology; for example, a mall intercept. This article explores alternative procedurers necessary to conduct consumer testing among Hispanic women. It is based on a substantial study conducted by a major consumer products company, and a major independent research firm and documents the planning and implementation of the study. It draws conclusions about Hispanics as a marketing and sensory research target, offers general direction for researchers approaching the Hispanic market for the first time and discusses such details as the need for over recruitment, nuances of language and various Spanish dialects, the need to simplify directions and the target audience's difficulty in dealing with the concept of quantifying the degree of liking and disliking.
Spectral Characteristics of Longitudinal Highway Profiles as Related to Ride Quality
Authors: Hayhoe GF
Published: March 2009

The spectral characteristics of 162 pavement profiles are examined and compared with subjective ratings of the ride quality of the profile sections in a search for explanations of certain apparent anomalies in the relationship between ride quality and profile characteristics. Many of the profiles are found to contain large numbers of pulse-like disturbances, with the pulses contributing a significant proportion of the energy in the profiles at high frequencies. It is argued that the presence of pulses in pavement profiles could be a significant factor in subjective response to road roughness, but no firm evidence could be found to support the proposal. The synthesis of pavement profiles for use in computer simulations is also discussed, and there is reason to suppose that the simple random process frequently used to describe pavement surfaces is a poor model of profile characteristics for many pavements.
Impact Factors for Highway Bridges
Authors: GangaRao HVS
Published: March 2009

This paper deals with the review of impact or dynamic allowance factors for highway bridges that are being implemented by various countries around the world. This review has specifically emphasized the field results of other researchers and concluded that most of the studies have noted that the current American Association of State Highways and Transportation Officials (AASHTO) Specifications grossly underestimate the impact factors for highway bridges. The review of impact factors herein has concluded further that the AASHTO Specifications on impact for highway bridges are a function only on the span length, even though many other important parameters (for example, road roughness, vehicle and bridge dynamics) play a major role in terms of bridge dynamics.

Test results of two medium span steel stringer concrete deck bridges (span length approx. 100 ft.) on West Virginia's highway systems are reported herein for varying truck speeds, and for various bridge natural frequencies, dynamic strains on stringers, concrete slabs, and abutments.

A deterministic procedure, based on the orthotopic plate theory that was developed at West Virginia University, has been used to compute frequencies, deformations and stresses. In addition, I-D beam theory has been used to compute natural frequencies. A comparison of these theoretical results with the experimental is found to be satisfactory.
ASTM Reformulated Gasoline Standards for a Clean Environment
Authors: France WD
Published: March 2009

ASTM has a 90-year history of providing an open forum for representatives from industry, government, academia, and the general-interest sector to develop high-quality, voluntary consensus standards. At this time, there is an urgent need for ASTM Committee D-2 on Petroleum Products and Lubricants to develop standards for automobile gasolines reformulated to reduce emissions, along with new methods to measure fuel composition and properties rapidly and with good precision. The result will be ASTM fuel standards for cleaner air.
Initial Results from the Auto/Oil Air Quality Improvement Research Program
Authors: McCabe LJ
Published: March 2009

The Auto/Oil Air Quality Improvement Research Program (AQIRP), a cooperative effort by the three major U.S. auto companies and fourteen oil companies, is the most comprehensive research effort ever undertaken to develop data on the air quality effects of the use of various motor fuels in various automotive systems and the relative cost-effectiveness of various fuel/vehicle combinations. Phase I of the Program, at a cost of about $15 million, is examining emissions and air quality impacts from current and older vehicles using reformulated gasolines with widely different values of aromatics content, olefin content, oxygenate content and type, sulfur content, vapor pressure (RVP) and 90% distillation temperature (T90). Emissions from Flexible and Variable Fuel vehicles using methanol/gasoline mixtures are also being examined. A second phase with a $25 million budget over three years has also been approved. Initial findings from the Phase I study and Phase II plans will be presented.
Diesel Fuel Modification for Reduced Exhaust Emissions
Authors: Winsor RE , Larkin DE
Published: March 2009

Modified diesel fuels have the potential to reduce engine-out exhaust emissions. Detroit Diesel has been testing diesel fuels with low sulfur and aromatics and higher cetane number, synthetic diesel fuels, and commercial fuels with various additives. Other industry programs have generated similar data. These results have led to the conclusion that a significant contribution toward reduced emissions can be made by modifying future diesel fuels. While more work needs to be done to properly specify a low emission diesel fuel, this paper is intended to stimulate interest in this subject and encourage engine manufacturers and fuel suppliers to work together to define an improved future fuel.
Experience and Initiatives in Replacing Ozone Depleting Chemicals for Precision Cleaning at the U.S. Air Force's Aerospace Guidance and Metrology Center
Authors: Hunt DE , Milholen CV
Published: March 2009

The Aerospace Guidance and Metrology Center has historically been a major user of Ozone Depleting Chemicals (ODCs) for precision cleaning operations. The Center has developed aqueous processes to the point where they are being implemented as alternatives for the vast majority of its precision cleaning requirements. Included in the materials and assemblies being cleaned with aqueous processes are beryllium and precision instrument bearings. The Center has also developed a method to quantitatively compare the cleaning effectiveness of one process to another. The method involves the use of stable isotopes and has proven to be effective for measuring organic contaminant removal in parts and assemblies with complicated geometries such as hidden cavities, dead end screw holes, small diameter fill tubes, etc.