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This paper presents a novel deep learning-based arterial pulse wave analysis (PWA) approach to diagnosis of peripheral artery occlusive disease (PAD). Naïve application of deep learning to PAD diagnosis can be hampered by the fact that securing a large amount of longitudinal dataset encompassing diverse PAD severity as well as anatomical and physiological variability presents formidable challenge. Training of a deep neural network (DNN) to a small training dataset raises the risk of overfitting the PAD diagnosis algorithm only to the individuals in the training dataset while deteriorating its ability to generalize also to other individuals who may exhibit a large variability in anatomical and physiological characteristics beyond the training dataset. To overcome these obstacles, we propose a continuous property-adversarial regularization (CPAR) approach to robust generalization of a DNN against scarce datasets. Our approach fosters the exploitation of latent features that can facilitate the intended task independently of confounding property-induced disturbances. by regularizing the extraction of disturbance-dependent latent features in the network’s feature extraction layer. By training and testing a deep convolutional neural network (CNN) for PAD diagnosis using scarce virtual datasets, we illustrated that the CNN trained by our approach was superior to a conventionally trained CNN in detecting and assessing the severity of PAD against disturbances originating from diversity in the patients’ height and arterial stiffness: when trained with one-time pulse wave signal measurement at ankle and brachial arteries in a small number of patients, our approach achieved detection accuracy of >90% and severity assessment of 0.83 in r2 value, which were >15% and >40% improvement over conventional approach without CPAR. In addition, we ascertained the advantage of our approach in efficient training and robust generalization of DNN by contrasting it to multi-task learning which promotes the exploitation (as opposed to regularization in CPAR) of disturbance-dependent latent features in fulfilling the intended tasks.

This study examined the electrical and self-sensing capacities of ultra-high-performance fiber-reinforced concrete (UHPFRC) with and without carbon nanotubes (CNTs). For this, the effects of steel fiber content, orientation, and pore water content on the electrical and piezoresistive properties of UHPFRC without CNTs were first evaluated. Then, the effect of CNT content on the self-sensing capacities of UHPFRC under compression and flexure was investigated. Test results indicated that higher steel fiber content, better fiber orientation, and higher amount of pore water led to higher electrical conductivity of UHPFRC. The effects of fiber orientation and drying condition on the electrical conductivity became minor as sufficiently high amount of steel fibers, 3% by volume, was added. Including only steel fibers did not impart UHPFRC with piezoresistive properties. Addition of CNTs substantially improved the electrical conductivity of UHPFRC. Under compression, UHPFRC with a CNT content of 0.3% or greater had a self-sensing ability that was activated by the formation of cracks, and better sensing capacity was achieved by including greater amount of CNTs. Furthermore, the pre-peak flexural behavior of UHPFRC was precisely simulated with a fractional change in resistivity when 0.3% CNTs were incorporated. The pre-cracking self-sensing capacity of UHPFRC with CNTs was more effective under tensile stress state than under compressive stress state.

Abnormal degradation of matrix components due to dysregulated expression of matrix metalloproteinase (MMP)-9 in macrophages has been linked to progression of acute cerebral ischemia and atherosclerosis. We report that lithium chloride (LiCl) or CHIR99021, inhibitors of Wnt signaling pathway, enhance phosphorylation of glycogen synthase kinase-3beta and suppress lipopolysaccharide-mediated upregulation of MMP-9 expression in murine macrophage RAW264.7 cells in a dose-dependent manner. Suppression of MMP-9 expression by LiCl or CHIR99021 did not result after inhibition of kinases involved in NFκB or AP-1 family proteins, but from changes in the activity of histone deacetylases. Beneficial effects on atherosclerosis or cerebral ischemia in animal studies caused by LiCl may be in part explained by the suppression of MMP-9 gene expression.

BMP-9, whose expression is highest in liver cells, has been demonstrated to regulate expression of enzymes involved in glucose homeostasis. However, the underlying mechanism of this effect has yet to be elucidated. We observed that MB109, a recombinant BMP-9 derivative, enhanced brown adipogenesis of human adipose tissue derived stem cells. With this observation of the cell culture system, we hypothesized that MB109 may be able to improve glucose metabolism by regulating expression of brown adipogenic genes. Systemic intraperitoneal injection of MB109 (200 μg/kg/wk) suppressed weight gaining of high fat diet-induced obese mice by reducing sizes of white adipocytes and decreased 16 h fasting blood glucose levels without changing food consumption or apparent behavioral performances. MB109 induced expression of brown adipogenic genes in the subcutaneous but not in the visceral fat tissues from the mice fed with high fat diet. In addition, systematic injection of MB109 enhanced fatty acid synthase expression in the liver of obese mice, which may help attenuate an obesity-associated increase of blood glucose levels. Our results demonstrate a role of BMP-9 in brown adipogenesis and suppressing pathophysiology of high fat diet-induced obesity, presumably through the activin receptor like kinase 1 signaling pathway.

The present paper introduces the manufacturing process and industrial applications of Alantum metal foams having a complete open-pore structure. Wide spectrum of foam products, based on several distinguished properties of metal foams is described. Examples of Alantum foam products, transited to the industrial applications are provided with the roles of foams during their performances.

The application of lightweight aluminum sheets to fabricate automotive components for vehicle weight reduction continues to be limited due to their low formability and high cost. This report summarizes a metallurgical investigation of the influence of various microstructural attributes on the forming and failure characteristics of aluminum sheets produced by lower cost continuous casting processes. The study has identified the combination of microstructural attributes, such as grain size, texture, and second phase particle distribution, in the sheets which make some sheets more formable than others and has traced the origin of these features to the processing history. The results show that the microstructural features present in the sheets have their origin in the casting, rolling, and recrystallization processes involved in their fabrication.

Uniaxial tensile properties influenced by the dynamic recrystallization (DRX) behavior of the partially strain-hardened magnesium AZ31 sheets (H24) containing scores of twins were investigated and compared to those of fully annealed ones (O) with absence of twins. For this purpose, a series of uniaxial tensile tests were carried out for the H24 and O materials at temperatures ranged from room temperature to 300 °C and at strain rates between 10−3 and 10−1 s−1. At 150 and 200 °C, the H24 material exhibited higher yield strength without much loss in elongation compared to those of the O material; this trend was attributed to the continuous DRX along or around grain boundaries as well as extensive twin-aided DRX inside grains. In addition, the post-deformation hardness value of the H24 material showed higher than that of the O material. On the other hand, at higher temperatures of 250 and 300 °C, it was observed that twins shown in the H24 material were disappeared even prior to deformation, resulting in the similar grain structure and mechanical property values to those of the O material, e.g., discontinuous DRX associated with grain boundary bulging. Finally, the initiation of DRX was rationalized in terms of microstructure morphology, deformation temperature and strain rate, and then modeled in the context of strain hardening rate analysis. A comparison of experimental results and predictions for both H24 and O materials showed that the model can provide a reasonable prediction of critical strain to initiate DRX.

The effect of uniaxial tensile prestrain and subsequent annealing on the post-annealing mechanical properties (elongation, yield stress and strain-hardening exponent) of AA5182-O was investigated. Experiments were performed at four prestrain levels (5, 10, 15, and 20%) and three annealing temperatures (300, 350, and 400 °C), with holding times ranging from 5 s to 1 h. Empirical models for the yield stress of post-annealing AA5182-O were developed in terms of the applied prestrain, annealing temperature, and time for static recovery and recrystallization processes. The strain-hardening exponent was shown to have a linear correlation with the logarithm of yield stress. The above models can be used in formability analyses and forming process optimization.

Microstructure and texture evolution of Mg–6Zn–1Mn–1Al (ZMA611) and Mg–6Zn–1Y (ZW61) alloys have been investigated. It is shown that recrystallization occurs through a shear (deformation) band nucleation mechanism. Alloy composition has a significant effect on the nature of the deformation bands formed during rolling, resulting in a difference in the orientation of recrystallized grains between the two alloys: double twin-related in ZMA611 and tension twin-related in ZW61. Such a contrast in microstructure results in the two alloys having different (00.2) pole figures.

The stretch formability of twin-roll cast (TRC) Mg alloys at room temperature has been investigated in relation to their work-hardening capacity. It is shown that there is a linear relationship between stretch formability and the work-hardening capacity, represented by the inverse of the yield ratio. The randomization of texture and the increase in grain size increase the work-hardening exponent, resulting in an improvement in the stretch formability of TRC Mg alloys at room temperature.

Room temperature formability of twin-roll cast Mg alloys has been investigated and correlated with their work hardening behavior. Tensile properties of these alloys were measured and their work hardening behaviour was analysed by using constitutive equations. Room temperature formability of the alloys was evaluated by the limiting dome height (LDH) value, obtained by the Erichsen cupping test. It shows that there is a linear relationship between LDH value and the inverse of yield ratio, which is a function of work hardening exponents. An increase in grain size increases work hardening exponent and concurrently increases LDH.

Magnesium sheet has received increasing interest for automotive body and closure applications. However, implementation of these applications faces many challenges involving room temperature formability. Hemming a closure panel with a magnesium outer panel will be difficult because of the sharp bend radius. Bending behavior of AZ31B-O at elevated temperatures was investigated to approximate the hemming of closure panels with acceptable surface appearance. Surface quality from small-radius bending was quantified as a function of temperature between 180 and 300 °C. Flanging with a 1.5 mm die radius yielded an acceptable surface quality at 210 °C and higher. Hemming required a minimum temperature of 270 °C for an acceptable surface condition with a 2 mm outer radius. The complex pattern of grain size and morphology of the deformed microstructure was documented with respect to the elevated temperature deformation behavior of Mg alloys. These results suggest that Mg can be hemmed at elevated temperatures with a small radius (∼1½ times the sheet thickness) and therefore could be used for vehicle closures.

An AA5083 aluminum alloy was modified with two different levels of Cu additions, cast by direct-chill method, and thermo-mechanically processed to sheet gauge. Copper additions reduced sheet grain size, decreased tensile flow stress and significantly increased tensile elongation under most elevated temperature test conditions. The high-Cu (0.8 wt.%) alloy had the finest grain size 5.3 μm, a peak strain-rate sensitivity of 0.6 at a strain-rate of 1 × 10−2 s−1, and tensile elongation values between 259 and 584% over the temperature range, 400-525 °C, and the strain rate range, 5 × 10−4 to 1 × 10−2 s−1, investigated. In biaxial pan forming tests, only the Cu-containing alloys successfully formed pans at the higher strain rate 10−2 s−1. The high-Cu alloy showed the least die-entry thinning. Comparison of ambient temperature mechanical properties in O-temper state showed the high-Cu alloy to have significantly higher yield strength, ultimate strength, and ductility compared to the base 5083 alloy.

Although BMP-9 has been reported to induce browning of white adipose tissues (WATs) and suppress high fat diet-induced obesity, detailed molecular mechanism needs to be further elucidated. We report here that administration of MB109, a recombinant derivative of human BMP-9, into obese mice enhanced gene expression of fibroblast growth factor 21 (FGF21), a metabolic regulator, and alleviates a spectrum of pathological symptoms due to high fat diet-induced obesity. In addition, periodical injection of MB109 (500 μg/kg/week) reduced an amount of lipid droplets in the liver, serum levels of alanine aminotransferase (ALT), and total cholesterol. These results indicate that MB109 is also effective to treat obesity-mediated non-alcoholic fatty liver disease (NAFLD).

Experimental observations show that the continuous cast (CC) Al–Mg alloy with 0.21 wt% Fe has a considerably lower fracture strain than that of a CC alloy with 0.08 wt% Fe and a direct chill cast (DC) alloy with 0.21% Fe. However, the forming limit strains are almost the same for the three alloys. The similarities and differences are thought to relate with the distribution of hard second-phase particles. In the present paper, the influence of particle distribution characteristics (random vs. stringer pattern) and volume fraction (1.2% vs. 3.5%) is examined in detail with the use of a simple plane stress finite element unit cell model. The model permits extension of the composite stress–strain curve beyond the diffuse necking condition so that the nominally uniform response is followed directly by localized necking. The model results agree very well with tensile tests with respect to the differing behaviour of the three materials in the deformation range between the onset of diffuse necking and that for localized necking.

A study has been made on the superplastic deformation behavior of warm-rolled 6013 Al alloy. A series of load relaxation tests have been carried out on a warm-rolled 6013 Al alloy. They are well interpreted by grain boundary sliding (GBS) and grain matrix plastic deformation (GMD) using the internal variable theory of structural superplasticity. Uniaxial tensile testing shows a maximum elongation of 370% achieved at 560 °C under the initial strain rate of 1 × 10−4 s−1. These conditions of maximum elongation are consistent with the load relaxation results.

A variety of surface observational techniques including full-field strain mapping based on digital image correlation analysis, electron back-scatter diffraction and in situ field emission scanning electron microscopy have been used to follow the patterns of inhomogeneous flow which occur during tensile testing of AA5754. The observations permit the relationships between slip lines, dynamic strain aging, shear localization, diffuse and localized necking to be delineated. In addition, fracture observation and metallographic assessment of damage processes have been conducted to enable an understanding of the relationship between inhomogeneous deformation and ductility to be developed.

Abnormal degradation of matrix components due to dysregulated expression of matrix metalloproteinase (MMP)-9 in macrophages has been linked to progression of acute cerebral ischemia and atherosclerosis. We report that lithium chloride (LiCl) or CHIR99021, inhibitors of Wnt signaling pathway, enhance phosphorylation of glycogen synthase kinase-3beta and suppress lipopolysaccharide-mediated upregulation of MMP-9 expression in murine macrophage RAW264.7 cells in a dose-dependent manner. Suppression of MMP-9 expression by LiCl or CHIR99021 did not result after inhibition of kinases involved in NFκB or AP-1 family proteins, but from changes in the activity of histone deacetylases. Beneficial effects on atherosclerosis or cerebral ischemia in animal studies caused by LiCl may be in part explained by the suppression of MMP-9 gene expression.

Superplastic deformation behavior of a fine grain 5083 Al sheet (Al-4.2 pct Mg-0.7 pct Mn, trade name FORMALL 545) has been investigated under uniaxial tension over the temperature range of 500 °C to 565 °C. Strain rate sensitivity values >0.3 were observed over a strain rate range of 3 × 10−5 s−1 to 1 × 10−2 s−1, with a maximum value of 0.65 at 5 × 10−4 s−1 and 565 °C. Tensile elongations at constant strain rate exceeded 400 pct; elongations in the range of 500 to 600 pct were obtained under constant crosshead speed and variable strain rates. A short but rapid prestraining step, prior to a slower superplastic strain rate, provided enhanced tensile elongation at all temperatures. Under the two-step schedule, a maximum tensile elongation of 600 pct was obtained at 550 °C, which was regarded as the optimum superplastic temperature under this condition. Dynamic and static grain growth were examined as functions of time and strain rate. It was observed that the dynamic grain growth rate was appreciably higher than the static growth rate and that the dynamic growth rate based on time was more rapid at the higher strain rate. Cavitation occurred during superplastic flow in this alloy and was a strong function of strain rate and temperature. The degree of cavitation was minimized by superimposition of a 5.5 MPa hydrostatic pressure during deformation, which produced a tensile elongation of 671 pct at 525 °C.

The recyclability of two commercial nylon 66/PPO [poly(phenylene oxide)] alloys has been investigated by examining the effects of multiple and abusive melt processes upon the impact strength. The loss of performance associated with these exposures has been correlated, in one instance, with the thermal degradation of polybutadiene-based impact modifier. The degradation of the rubber has been quantified using an indirect measurement of rubber mobility obtained from the NMR free induction decay of mobile and rigid protons in the material. Substitution of the unsaturated rubber modifier with a saturated hydrocarbon resulted in improved recyclability. Both formulations provide evidence of changes in morphology related to instability of the dispersed PPO phase. The coalescence of PPO particles, evident in later stages of prolonged thermal exposure, appears to cause further loss of impact strength. Currently the chemical and / or physical changes responsible for the increase in average PPO particle size are not known. It is probable that the thermal stability of the compatibilizer, formed during the reactive extrusion manufacturing process, may be insufficient to provide a durable morphology for repeated recycling of these alloys.

Superplastic forming characteristics of a fine-grained 5083 aluminum sheet have been investigated by means of gas-pressure forming of a rectangular pan. This part geometry lends itself to a simple representation in terms of nearly one-dimensional sheet stretching and permits reasonably rigorous control of strain rate throughout the forming cycle. This study followed a study of the uniaxial tensile properties carried out on this alloy. A two-stage forming cycle, which comprised a short, rapid prestraining stage followed by a stage of slower rate of superplastic straining, was used because the uniaxial tensile work showed enhancement of superplastic response of this alloy under this condition. The study examined the effect of process parameters such as initial gas pressurization rate, level of hydrostatic pressure, and lubricants on the thinning characteristics of the sheet, especially along the die entry radii. The gas pressure/time cycle was suitably modified to avoid premature sheet failure due to excessive sheet thinning or cavitation. Cavitation under the biaxial forming condition and the effect of hydrostatic pressure on cavitation suppression were evaluated. A defect-free pan with sharp corners was formed.

A preliminary investigation of thermomechanical processing of 5083 aluminum plate (Al-4.7%Mg-0.7%Mn) was undertaken to develop a fine-grain sheet for superplastic forming applications. Significant differences in grain size and the extent of superplasticity are seen in hot-rolled vs. cold-rolled sheets, with tensile elongations exceeding 600% for the cold-rolled alloy. Additionally, a separate fine-grain sheet of the same alloy, produced by Alusuisse Co., was studied in greater detail. Superplastic deformation behavior of this sheet was investigated under uniaxial tension over the temperature range of 500–565 °C. Strain rate sensitivity values greater than 0.3 were observed over a strain rate range of (3 × 10−5)–(1 × 10−2) s−1 with a maximum value of 0.65 obtained for strain rate of 5 × 10−4 s−1 at 565 °C. Constant-velocity tension tests consistently show larger strains to failure and lower strain hardening rate than the corresponding “constant-strain-rate” tests for the range investigated. A short but rapid prestraining step, prior to the normal superplastic straining, produced enhanced tensile elongation at all temperatures. Under the two-step schedule, a maximum tensile elongation of 600% was obtained at 550 °C, which was regarded as the optimum superplastic temperature under this condition. This paper and a companion paper are used to provide the details of results obtained to date from this study.

There is considerable worldwide interest in magnesium (Mg) sheet as a replacement for heavier steel and aluminum alloys in vehicle closure components. As Mg gains acceptance in the automotive industry, there will be an increasing demand for accurate material properties for finite element simulations of Mg structures. In this paper, we investigate the extent to which average grain size and postformed tensile properties vary across a Mg AZ31B hood inner component formed at 485°C for 20 min under a constant gas pressure. Tensile specimens were extracted from six regions of the hood inner, which underwent varying degrees of thinning. A state-of-the-art digital image correlation (DIC) algorithm and custom image acquisition software provided true stress-true strain data for each specimen. Tensile data acquired during room temperature testing was compared with that from baseline (undeformed) Mg AZ31B in a fully recrystallized condition (O-temper). Due to its importance in finite element simulations, particular emphasis was placed on the variation of postformed yield strength with specimen thickness and average grain size. Finally, we compute local strain fields during fracture in a tensile specimen with DIC grids positioned in the failure region.

In this work, a novel approach has been proposed to predict shear band formation under uniaxial tension. The approach postulates a heterogeneous distribution of mechanical properties through the starting material. The model is used to study the effect of such heterogeneity on the development of shear localization with increasing strain. A correlation between diffuse and localized necking, and strain‐hardening rate has been found. The predicted force‐displacement curves and the limit strains to failure agree well with experimental observations.

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The laser transformation hardening response of Fe-0.5C-0.8Mn and Fe-0.5C-0.8Mn-0.8Cr steels was examined. A 2 kW CO2 laser was used to scan the steel surfaces at various rates. Complete transformation of pearlite to austenite, and hence to martensite, occurred in the laser heated surface layer of the Fe-C-Mn steel. During equivalent heat treatment of the Fe-C-Mn-Cr steel, incomplete austenitization of the pearlite colonies left the cementite plates largely undissolved. However, the maximum surface hardness was approximately the same for both alloys. Comparison of calculated and measured hardened depths yielded values of the effective coupling coefficient of the laser beam to the steel which varied as a function of beam interaction time. Modeling the process allowed a dis-tinction to be made between the effects of alloying elements and of pearlite spacing upon the depth of complete austenitization. In this case, the effect of the difference in pearlite spacing between the two steels was negligible. In the alloy steel, Cr and Mn were strongly partitioned to the cementite before heat treatment, and remained so after laser processing. Incomplete austenitization of that steel is attributed to partitioning of alloying elements to the cementite and their retarding influence on the diffusion controlled dissolution kinetics of the alloyed carbide.

Successful laser transformation hardening of steel surfaces requires that the absorbed laser energy is sufficient to austenitize the initial microstructure to a depth of 0.5 mm or more. Hardening is accomplished when rapid cooling by conduction of heat away from the surface causes transformation of the austenite layer to martensite. Heating and cooling rates of 10/sup 4/ K/s or greater are typical of the laser hardening process and the entire thermal cycle may be accomplished in less than 0.1 s. In an earlier study, laser surface hardening of commercial plain carbon and chromium alloyed steels was examined. It was shown that in the alloyed steel chromium enrichment of the cementite in the initial microstructure could prevent complete transformation of pearlite to asutenite during the very rapid laser heating cycle. However, interpretation of the results was complicated somewhat by the fact that manganese was also partitioned to the cementite. The purpose of this work was to conduct selected identical laser heating experiments on a high-purity Fe-C-Cr alloy to test the effect of chromium unequivocally, i.e., in the absence of manganese and other elements normally present in commercial steels.

Ferrite/graphite and martensite/graphite interfaces in three commercial cast irons have been analyzed using transmission electron microscopy. Two recurring orientation relationships have been found to account for over 60 pct of the ferrite/graphite interfaces analyzed. A similar pair of relationships discovered in martensitic material strongly suggests that the prior austenite/graphite interface was also ordered. The same relationships were prominent in gray and ductile irons. One of the relationships observed can be transformed through the Kurdjumov-Sachs relationship to a previously-reported austenite/graphite relationship.

Electron probe microanalysis (EPMA) and analytical electron microscopy (AEM) were used to characterize the changes that occur on a vehicle-aged three-way automotive catalyst as a result of two rejuvenation treatments. One treatment involves washing a catalyst with an aqueous solution of oxalic acid followed by calcination. This treatment results in the redistribution of phosphorus- and lead-based poison deposits, but leaves silicon- and sulfur-containing species in place. Noble metal radial profiles within the catalyst appear to be unaffected. Some evidence was found that this washing treatment may reverse the segregation of Pd in multimetallic Pt/Pd particles. The second treatment involves the redispersion of the noble metals by a high-temperature chlorination. This process has little effect on poison or noble metal radial distributions within the catalyst pellet. However, substantial reduction in the noble metal particle size was observed; particle size distributions which are comparable to those observed on fresh catalysts were produced by this treatment. The redispersed noble metal particles were generally multimetallic, indicating little bulk separation of the noble metals from the multimetallic particles originally present on the aged catalyst.

The microscopic details of fresh and vehicle-aged commercial pelleted automotive exhaust catalysts containing Pt, Pd and Rh were studied by employing analytical electron microscopy (AEM). Two different vehicle-aged samples containing similar poison levels but having different catalytic activities (denoted better and poorer) were selected for this study. The general microstructure of the supports and the noble metal particles of the two aged catalysts were found to be similar but the average noble metal particle size on the poorer catalyst (21 nm) was larger than that on the better catalyst (16 nm). These sizes represent a significant increase in particle size over that found on the fresh catalyst (8 nm). The activity of these catalysts decreases as the observed particle size increases. The fresh and better catalyst had a more uniform distribution of particle sizes over the full depth of the pellet impregnation zone while the particle size on the poorer catalyst increased significantly with depth. Nearly all the noble metal particles observed on both the fresh and the two aged catalysts were bi-or trimetallic. For each catalyst, the particle composition was a function of radial position. This radial dependence of composition is a result of the different impregnation profiles of the individual noble metals which were determined by electron probe microanalysis (EPMA). The larger Pt/Pd bimetallic particles on the better catalyst were homogeneous with little, if any, Pd enrichment of the surface. Such particles on the poorer catalyst exhibited non-uniform surface and bulk distribution of Pt and Pd. For all catalysts, the presence of Rh was readily detected by EPMA but was difficult to find in the observable noble metal particles. For both catalysts, the major poison deposits were concentrated in a zone less than 10 μm deep. Major contaminants were P, Pb, Zn, Ca and Si which were present as dense, noncrystalline deposits, often appearing as a shell covering the surface of the catalyst pellet. These observations support the pore mouth blockage model of poisoning. No information concerning the presence of poisons on the surfaces of noble metal particles was obtained.

Automotive catalysts have a general loss of activity during aging, basically due to two principal deactivation mechanisms. One of them is thermally induced “sintering,” which results in catalytic surface area reduction. The other is chemically induced “poisoning,” which in part causes blockage of active metal sites. The conventional bulk techniques have indicated that various catalyst functions were affected differently by poisons and thermal damage; however, they generally did not provide detailed descriptions of the mechanisms of deactivation. Only analytical electron microscopy (AEM) can provide microchemical and microstructural information to gain a more thorough and fundamental understanding of catalytic deactivation.Fresh and vehicle-aged commercial automotive catalysts containing Pt, Pd, and Rh on alumina supports were prepared for AEM by a microtomy technique, which retains the spatial integrity of the catalyst pellet with uniform thickness. Then these AEM specimens were characterized in a transmission electron microscope (TEM) and in a dedicated scanning transmission electron microscope (STEM).