Small Blisters Research Articles

Effect of notches on creep–fatigue behavior of a P/M nickel-based superalloy

A study was performed to determine and model the effect of high temperature dwells on notch low cycle fatigue (NLCF) and notch stress rupture behavior of a fine grain LSHR powder metallurgy (P/M) nickel-based superalloy. It was shown that a 90second (s) dwell applied at the minimum stress (“min dwell”) was considerably more detrimental to the NLCF lives than similar dwell applied at the maximum stress (“max dwell”). The short min dwell NLCF lives were shown to be caused by growth of small oxide blisters which caused preferential cracking when coupled with high concentrated notch root stresses. The cyclic max dwell notch tests failed mostly by creep accumulation, not by fatigue, with the crack origin shifting internally to a substantial distance away from the notch root. The classical von Mises plastic flow model was unable to match the experimental results while the hydrostatic stress profile generated using the Drucker–Prager plasticity flow model was consistent with the experimental findings. The max dwell NLCF and notch stress rupture tests exhibited substantial creep notch strengthening. The triaxial Bridgman effective stress parameter was able to account, with some limitations, for the notch strengthening by collapsing the notch and uniform gage geometry test data into a singular grouping.

Congenital intraoral Fordyce spots

A term newborn boy born to primigravida by spontaneous vaginal delivery presented with poor feeding and small blisters in the lower lip and oral mucosa. The mother had an uneventful...

Amoxycillin and clavulanic acid induced Stevens-Johnson syndrome: a case report

Stevens-Johnson syndrome (SJS) is an immune complex mediated hypersensitivity complex that typically involves the skin and the mucous membranes. Various etiologic factors (e.g., infection, drugs and malignancies) have been implicated as causes of Stevens-Johnson syndrome. However, as many as half of the cases are idiopathic. Bastuji and Roujeau proposed that the denomination of Stevens-Johnson syndrome should be used for a syndrome characterized by mucous membrane erosions and widespread small blisters that arise on erythematous or purpuric maculae that are different from classic targets. In this case report, a 6 year old girl who was administered a cough syrup (containing bromhexine, guaiphenesin, diphenhydramine and phenylephrine) and amoxycillin and clavulanic acid dispersible tablet for the treatment of cough developed pruritic skin eruptions all over the body along with painful erosions on the tongue, buccal mucosa, genital and anal mucosa. A diagnosis of Stevens-Johnson syndrome was made. Amoxycillin and clavulanic acid combination was identified as the culprit based on the temporal relationship between the drug administration and the appearance of the rashes and based on a number of SJS reports implicating amoxycillin and clavulanic acid having been published before. The cough syrup and amoxycillin and clavulanic acid combination tablets were immediately stopped. Symptomatic treatment was administered. The child improved and was later discharged. Causality assessment using Naranjo adverse drug reaction probability scale revealed that amoxycillin and clavulanic acid combination was a possible cause for the harmful cutaneous adverse reaction with a score of 4.

Influence of hydrogen fluence on surface blistering of H and He co-implanted Ge

The effect of hydrogen fluence on surface blistering of H and He co-implanted Ge is investigated using atom force microscope, X-ray diffraction and transmission electron microscopy. With a fixed He, we find that for 1×1016cm−2 H implantation fluence, only a few small dome-shaped blisters appear, for 3×1016cm−2 H implantation fluence, large blisters as well as craters are formed, while for 5×1016cm−2 H implantation fluence, no blisters can be observed. The strain evolution and platelet forming tendency are found to be relevant for the different blistering phenomenon. The weak blistering phenomenon for 1×1016cm−2 H implantation fluence may be attributed to less “free” H for the building up of internal pressure of platelets and the sustained growth of platelets. While the absence of blistering phenomenon for 5×1016cm−2 H implantation fluence is likely due to the retarded relief of the decreased uniform compressive stress throughout the damage region.

Retrieval analysis of titanium nitride (TiN) coated prosthetic femoral heads articulating with polyethylene

Data regarding in vivo performance of titanium nitride (TiN) coated prosthetic femoral heads is scarce, and available studies of older generations of implants demonstrated coating wear in vivo. That is why we conducted a retrieval analysis of 11 femoral heads (articulating in vivo for 1–56 months) with TiN film formed using physical vapor deposition (PVD), to verify if coating failure is a problem in contemporary implants. Retrieved implants were examined using scanning electron microscope, coating roughness was evaluated with a contact profilometer and adhesion was tested using a Rockwell HRC test according to VDI 3824 guideline. Although no gross failure of the TiN coating was observed in our retrievals, all implants had defects typical for PVD coatings, such as pinholes, small titanium droplets and blisters with delaminated coating. In some heads the coating was contaminated with small niobium (Nb) droplets uniformly scattered on the entire surface of the film. Presence of Nb contamination was associated with an increased number and area of other types of defects and poorer coating adhesion. In one component, subjected to multiple dislocations we found severe delamination and cracking of the coating, increased roughness and the presence of third bodies. Our results indicate, that although wear of the coating is lower than seen in older generations of implants, inconsistent quality of the TiN film among different implants indicates the need for strict monitoring of the manufacturing process.

Blistering during the atomic layer deposition of iridium

The authors report on the formation of blisters during the atomic layer deposition of iridium using iridium acetylacetonate and oxygen precursors. Films deposited on fused silica substrates led to sparsely distributed large blisters while in the case of silicon with native oxide additional small blisters with a high density was observed. It is found that the formation of blisters is favored by a higher deposition temperature and a larger layer thickness. Postdeposition annealing did not have a significant effect on the formation of blisters. Finally, changing purge duration during the film growth allowed us to avoid blistering and evidenced that impurities released from the film in gas phase were responsible for the formation of blisters.

Deposition and characterization of E-paint on magnesium alloys

Abstract Electrophoretic paint (E-paint) was investigated on four different magnesium substrates: as-extruded AZ61 (AZ61), heat-treated AZ61 (AZ61-H), as-extruded TZ61 (TZ61) and heat-treated TZ61 (TZ61-H), to elucidate the effect of heat treatment and alloying elements on the deposition and characterization of E-paint. It was found that, a rapid increase of voltage, indicating the deposition of E-paint, was observed after an induction time of 0.39 min for AZ61-H, 0.43 min for AZ61, 0.51 min for TZ61-H and 0.58 min for TZ61. The amount of E-paint deposited on the four different samples was approximately similar, but the electrical charge used for the deposition process on the heat-treated samples was smaller than that on the as-extruded samples. Current efficiencies of E-painting on AZ samples (AZ61 and AZ61-H) were higher than those of TZ samples (TZ61 and TZ61-H), and the current efficiencies on the heat-treated samples were higher than those on as-extruded samples. All E-paintings on the four different magnesium substrates had an excellent adhesion without showing any detachment by tape peel test. After immersion test in deionized water (DI water) for 500 h at 40 °C, however, many large blisters were formed on the surface of AZ samples, and none or small blisters were observed on TZ samples. Salt spray test (SST) results showed that blisters were formed adjacent to the scratches on the E-painted AZ samples, while they were formed at the intact areas of E-painted TZ samples. The E-paints on heat-treated samples showed much better corrosion resistance than those on as-extruded samples.

Effects of initial blister radius and shaft diameter on energy release rate of metal–polymer composite coating

Shaft loaded blister tests were performed to study the interfacial fracture behaviour of a polymer composite coating material adhesively bonded to a metal substrate. For this purpose, the energy release rate required to propagate the crack along the polymer composite coating–metal interface was measured. To do this, six different initial blister radii (a), three different loading rates and two different spherical ended shaft sizes were employed. Fresh water conditioning at 55°C for 1000h was also carried out on the blister specimens to study the environmental effect on the total energy release rate (GT) of initial blister debonding. For a 5mm diameter shaft, with the increase of loading rate, the GT values were found to increase for the controlled samples while the loading rate followed the similar trend with lower GT values for the conditioned samples. The GT values obtained using two different shaft sizes showed that the larger shaft diameter had higher GT values than the smaller shaft diameter. Conditioned specimens tested using both of the loading shafts were generally found to have lower GT values than the controlled specimens. A comparison with the linear and nonlinear finite element analyses reveals the application ranges of the solutions for determining the energy release rate based on the plate bending model or the nonlinear membrane model. It is shown that the plate based energy release rate solutions should be used for a small blister and the membrane based solution should be adopted for a large blister.

Exposure of Equal-Channel Angular Extruded Tungsten to Deuterium Plasma**supported by the National Magnetic Confinement Fusion Science Program of China (Nos. 2013GB105001, 2013GB105002, 2015GB109001), National Natural Science Foundation of China (Nos. 11305213, 11405201), Technological Development Grant of Hefei Science Center of CAS (No. 2014TDG-HSC003), and China National Funds for Distinguished Young Scientists (No. 51325103)

Surface morphology and deuterium retention in ultrafine-grained tungsten fabricated by equal-channel angular pressing (ECAP) have been examined after exposure to a low energy, high-flux deuterium (D) plasma at fluences of 3×1024 D/m2 and 1×1025 D/m2 in a temperature range of 100°C-150°C. The methods used were scanning electron microscopy (SEM) and thermal desorption spectroscopy (TDS). Sparse and small blisters (∼0.1 μm) were observed by SEM after D plasma irradiation on every irradiated surface; yet they did not exhibit significant structure or plasma fluence dependence. Larger blisters or protrusions appeared after subsequent TDS heating up to 1000°C. The TDS results showed a single D desorption peak at ∼220°C for all samples and the D retention increased with increasing numbers of extrusion passes, i.e., the decrease of grain sizes. The increased D retention in this low temperature range should be attributed to the faster diffusion of D along the larger volume fraction of grain boundaries introduced by ECAP.

Friction fade-out at polymer-like carbon films slid by ZrO2 pins under hydrogen environment

Friction tests using ceramic pins against fully hydrogenated diamond-like carbon (polymer-like carbon, PLC) film under H2/He mixed gas or pure H2 gas environment were conducted. The test results of ZrO2 (YSZ: yttria-stabilized zirconia) pin slid against PLC film with an applied load of 4.9 N showed that the friction coefficient dropped to the tribometer noise level (friction fade-out, FFO) as low as 0.0002. In another experiment with the same materials and with an applied load of 30.4 N, the friction coefficient dropped to 0.0001–0.0005, which continued more than 4 h. Optical microscope and scanning electron microscopic observations, nano-indentation, surface profiler, X-ray photoelectron spectroscopy, Raman, and time-of-flight secondary ion mass spectrometry measurements were conducted and the mechanism for inviting FFO is investigated. It is found by an optical microscopic observation that the transfer film has small blisters, indicating some gaseous substance is generated at the ZrO2 surface. It is discussed based on the measurements that ZrO2 catalysis plays very important roles for gaseous substances generation and for H-passivation on both PLC and transfer film surfaces, which are closely relating to FFO through gas-lubrication effect, and through reducing adhesive force, respectively.

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN): could retinoids play a causative role?

Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) are overlapping manifestations on a spectrum of acute drug-induced conditions associated with severe blistering, skin peeling, and multi-organ damage. TEN is an eruption resembling severe scalding, with ≥30% skin detachment. SJS is a mild form of TEN, characterized histologically by epidermal keratinocyte apoptosis with dermo-epidermal separation and extensive small blisters with <10% body surface skin detachment. The syndrome can be induced by numerous medications and typically occurs 1–4 weeks after the initiation of therapy. Granulysin is found in the lesions of patients with SJS/TEN and plays a significant pathogenic role in the condition, but the overall mechanisms linking medications, granulysin, and disease manifestations remain obscure. This paper reviews evidence suggesting that the different medications implicated in SJS/TEN have the common property of interacting and synergizing with endogenous retinoids (vitamin A and its congeners), in many instances causing the latter to accumulate in and damage the liver, the main storage organ for vitamin A. It is hypothesized that liver damage leads to the spillage of toxic retinoid compounds into the circulation, resulting in an endogenous form of hypervitaminosis A and cytotoxicity with widespread apoptosis, mediated by granulysin and recognized as SJS/TEN. Subject to testing, the model suggests that symptom worsening could be arrested at onset by lowering the concentration of circulating retinoids and/or granulysin via phlebotomy or plasmapheresis or by pharmacological measures to limit their expression.

&lt;em&gt;Zygostates alleniana&lt;/em&gt; (Orchidaceae: Epidendroideae: Cymbidieae: Oncidiinae): estructura floral relacionada con la polinización

Gomiz, N.E., Torretta, J.P. & Aliscioni, S.S. 2014. Zygostates alleniana (Orchidaceae: Epidendroideae: Cymbidieae: Oncidiinae): Floral structure related to pollination. Anales Jard. Bot. Madrid 71(1): e002. The genus Zygostates Lindl. (Orchidaceae) comprises about 20 species of small Neotropical epiphytic plants, represented in its southernmost limit by the species Z. alleniana. In this paper, we studied morpho- logical and anatomical floral characteristics of this species related to pollination mechanism. We confirmed the presence of the unicellular trichomes on the base of the lip and side lobes secreting oil, constitut- ing a trichomal elaiophore. The oil is deposited beneath the cuticle at the apex of the trichomes forming small blisters. The oil could repre- sent a reward for the species Lophopedia nigrispinis, which would be a potential pollinator of Z. alleniana in a natural area within the geo- graphic range of this plant species. Moreover, we prove that the recon- figuration of the pollinaruim is due to the dehydration of the walls cell. This reconfiguration could favor cross-pollination mechanism already described for other species of the family Orchidaceae. Finally, we dis- cuss the floral characters present in Z. alleniana with closely related species.

Suppression of hydrogen-induced blistering of tungsten by pre-irradiation at low temperature

Blistering of tungsten (W) surfaces due to deuterium (D) implantation was investigated by a sequence of exposures at two different temperatures—230 and 450 K—and by the reversed sequence. A single exposure at 230 K leads to a high areal density of small dome-shaped blisters (up to 3 µm in diameter) together with much smaller flat-topped structures, while a single 450-K exposure produces large dome-shaped blisters up to 40 µm in diameter without the flat-topped structures. Most of the small dome-shaped blisters from 230 K exposure disappeared after annealing at 450 K for 17 h, but survived and even grew in size if the surface was exposed to D plasma during annealing. Sequential exposure at the two temperatures reveals a non-commutative behaviour: after a first exposure at 450 K the second exposure at 230 K leads to superposition of the observed blister structures without changing the large blisters from the first exposure. By contrast, a first exposure at 230 K almost completely suppresses the formation of large blisters during a second exposure at 450 K. Obviously, the presence of the small blisters strongly influences the penetration of D into the W bulk.

Surface morphology and deuterium retention in tungsten and tungsten–rhenium alloy exposed to low-energy, high flux D plasma

Surface topography and deuterium retention in polycrystalline hot-rolled W and W–5%Re have been examined after exposure to a low-energy (76eV), high flux (around 1022D/m2s) deuterium plasma to an ion fluence of 1026D/m2 at various temperatures. The methods used were confocal laser scanning microscopy and the D(3He, p)4He nuclear reaction at 3He energies varied from 0.69 to 4.0MeV. During exposure to the D plasma at temperatures in the range from 348 to 673K, small blisters of size in the range from about 1 to about 15μm, depending on the exposure temperature, are formed on the W and W–5%Re surfaces. In the W–5%Re, the deuterium retention demonstrates its maximum at exposure temperature of 463K, while in the W this maximum is shifted to 523K. A difference in the temperature dependence of the D retention for the W and W–5%Re is explained, as a rough approximation, by temperature dependences of the ductility of these materials.

Influence of particle flux density and temperature on surface modifications of tungsten and deuterium retention

Systematic study of deuterium irradiation effects on tungsten was done under ITER – relevant high particle flux density, scanning a broad surface temperature range. Polycrystalline ITER – like grade tungsten samples were exposed in linear plasma devices to two different ranges of deuterium ion flux densities (high: 3.5–7·1023D+/m2s and low: 9·1021D+/m2s). Particle fluence and ion energy, respectively 1026D+/m2 and ∼38eV were kept constant in all cases.The experiments were performed at three different surface temperatures 530K, 630K and 870K. Experimental results concerning the deuterium retention and surface modifications of low flux exposure confirmed previous investigations. At temperatures 530K and 630K, deuterium retention was higher at lower flux density due to the longer exposure time (steady state plasma operation) and a consequently deeper diffusion range. At 870K, deuterium retention was found to be higher at high flux density according to the thermal desorption spectroscopy (TDS) measurements. While blisters were completely absent at low flux density, small blisters of about 40–50nm were formed at high flux density exposure. At the given conditions, a relation between deuterium retention and blister formation has been found which has to be considered in addition to deuterium trapping in defects populated by diffusion.

Fracture of Zircaloy-4 cladding tubes with or without hydride blisters in uniaxial to plane strain conditions with standard and optimized expansion due to compression tests

Two optimizations of the Expansion Due to Compression (EDC) test, which induces a near uniaxial loading, were proposed and developed to reach higher biaxiality ratios (ratio between mechanical quantities in axial and in circumferential direction). The first optimization, named HB-EDC for High-Biaxiality EDC, allowed to reach transverse plane strain conditions. The second optimization, named VHB-EDC for Very High Biaxiality EDC, was designed to reach higher loading biaxiality ratios. These optimized EDC tests were performed at 25°C, 350°C and 480°C on unirradiated hydrided Cold Worked Stress Relieved (CWSR) Zircaloy-4 samples. First, samples unhydrided or uniformly hydrided up to 1130wppm were tested. Second, samples hydrided at 310wppm with a hydride blister were tested. A large ductility reduction is induced by the increase in biaxiality level in the absence of a hydride blister or with small blisters (<50μm deep). The fracture strain decreases quickly with the blister depth at 25°C, but more progressively at higher temperature. An equation that quantifies the fracture strain reduction with the blister depth is proposed. Eventually, one of the tests developed in the present study, the HB-EDC test, was proven to be a good compromise between the test complexity and the stress state reached. It is a good candidate to characterize the mechanical behaviour of irradiated cladding.

PS-071 Telaprevir-induced Stevens-Johnson Syndrome. A case report

BackgroundThe introduction of triple treatment for the treatment of hepatitis C virus (HCV) has achieved cure rates of 75% in genotype 1 treatment-naïve patients and about 50% in those who...

Mark-Recapture Study of Gnathium minimum (Say) (Coleoptera: Meloidae) Reveals Limited Dispersal Among Helianthus occidentalis Patches

ABSTRACT: Mark-release-recapture provides a technique to estimate population sizes, dispersal, survival, and demographic data. This technique was employed with the small blister beetle, Gnathium minimum, at Spring Green Prairie State Natural Area from 24 July to 16 August 2008. Of 104 marked adults, 54 were recaptured; a maximum of 34 were observed during a single survey and a maximum daily Jolly-Seber population size estimate of 59 individuals was calculated. Most individuals remained within 12 m of their original capture location, suggesting they remained within the same patch of Helianthus occidentalis flowers or an adjacent patch. The furthest movement observed was 601 m.

Quantifying blistering and browning properties of Mozzarella cheese. Part II: Cheese with different salt and moisture contents

Blistering and browning are two important properties when baking Mozzarella cheese on pizza. In this study, the blistering and browning of five Mozzarella cheeses with different salt and moisture contents were evaluated using machine vision and image analysis techniques. Cheese attributes, including meltability, free oil, elasticity and stretching properties, composition, water activity and microstructure, were also evaluated.All Mozzarella samples had similar browning appearances, due to their similar galactose contents. Mozzarella cheeses with higher salt concentration had relatively smaller fat globules and lower water activity, thus higher transition temperature, and elastic and stretching resistances which resulted in smaller blisters on the pizza. It was proposed that cheese with higher transition temperature had a shorter time to flow, and the elastic and stretching resistances of the melted cheese restrained the size of the blisters and impeded the growth of the blisters during heating.

A Comparative Study of Hydrogen Implantation Induced Blistering and Exfoliation in GaN and AlN

GaN and AlN epitaxial layers were implanted with 100 keV H+ ions at implantation temperatures of RT and 300 °C. The GaN and AlN were H-implanted with fluence of 2.5 ×1017 and 1 ×1017 cm-2, respectively, in order to observe the surface blistering. The morphological investigations revealed that post-implantation annealing resulted in the formation of small size surface blisters with lower exfoliation depth in GaN compared to AlN for the implantation at RT. However, for the implantation at 300 °C, blistering occurred in the as-implanted GaN, whereas large area exfoliation was observed in AlN after annealing. Transmission electron microscopy (TEM) images showed formation of narrower damage band in AlN (as compared to GaN) filled with H-induced nanovoids. This comparative study has shown that H-induced damage and depth distribution of the implanted hydrogen was responsible for the nature of surface buckling in H-implanted GaN and AlN.