Blistered Surface Research Articles

Ageing processes of coil-coated materials: Temperature-controlled electrochemical impedance analysis

In the present work, an industrial polyester coil-coated steel was characterized by electrochemical impedance spectroscopy (EIS) during immersion in a 0.5 M NaCl solution for different temperatures (30, 40, 50 and 60 °C). The objective was to propose a methodology to follow the ageing of the coil-coated system, from the first stage of water uptake until the blistering appearance. Relevant parameters were extracted from the EIS diagrams to analyse ageing processes of the polymer and of the metal/polymer interface. Water uptake was determined from the high-frequency part of the impedance diagrams using a linear rule of mixtures. By increasing the temperature, both the water uptake kinetics and the water content in the coating increased. The effect of water uptake on the physical structure of the coating (plasticization) was discussed through the analysis of a time constant corresponding to the dielectric manifestation of the polymer glass transition.At 40, 50 and 60 °C, appearance of corrosion was detected on the impedance spectra by a decrease, at low frequency, of the impedance modulus and of the phase angle. For 60 °C, the corroded surface area as a function of time, was assessed from the EIS data analysis with adapted equivalent circuits. The corroded surface areas followed similar trend as blister surface areas determined from images analysis.

Bullous pemphigoid and dipeptidyl peptidase-4 inhibitors: Evaluation of the clinical course and treatment response.

Dipeptidyl peptidase-4 inhibitors (DPP4is), drugs used to treat type 2 diabetes mellitus (DM2), show a significant association with bullous pemphigoid (BP) development. In this retrospective cohort study, we evaluated the clinical course and development of BP among patients with DM2 treated with DPP4is. This retrospective cohort study included all the patients with BP and comorbid DM2 who visited Sheba hospital during 2015-2020. Among 338 patients with BP, 153 were included in our study. In 92 patients, BP diagnosis was attributed to the use of DPP4is. DPP4i-associated BP patients had fewer neurological and cardiovascular comorbidities and higher blistered body surface area (BSA) at first presentation, with noticeable upper and lower limb involvement. These patients were younger and more responsive to treatment, with a greater reduction in the BSA score after two months of treatment. The clinical features of patients with BP treated with DPP4is were initially more severe; however, during follow-up, a marked clinical improvement was noticed, especially among patients who had ceased the drug. Therefore, although withdrawal of the drug may not impose disease remission, it can alleviate the disease course and avert the need for treatment escalation.

Degradation of Polyfurfuryl Alcohol-Based Biopolymer by Soil-Burial and Photo-Degradation Methods

Recently, polyfurfuryl alcohol (PFA) based material has been gaining attention. Despite its use as an intermediate in various industries, the degradation process of PFA has rarely been reported. In this study, neat PFA (PF) and polylactic acid (PLA) incorporated PFA (PF-PL) based thermoset biopolymers were prepared by casting method. The degradation of the prepared biopolymer specimens was carried out under environmental conditions via soil-burial test and photo-degradation method for 21-months. The extent of degradation of PF and PF-PL was assessed by evaluating weight loss, variation in mechanical properties and change in complex viscosity. Structural and morphological changes of degraded PF and PF-PL samples were evaluated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. Weight loss percentage in case of photo-degraded samples was found to be much higher compared to soil buried specimens. SEM micrographs showed a blistered surface and visible cracks on the surface of soil buried and photo-degraded samples, respectively. FTIR spectra of photo-degraded samples showed a new peak at 673 cm−1 indicating the furan ring opening during the degradation process. Significant variation in mechanical properties of PF and PF-PL specimens after soil-burial test also indicated biodegradable nature of the biopolymers. Approximately 45% and 63% of loss in tensile strength was obtained in PF and PF-PL soil buried specimens, respectively. Complex viscosity was lowest for PF and PF-PL samples after 21 months of degradation compared to undegraded specimens thus indirectly indicating the decrease in molecular weight after degradation. All the obtained data revealed the fragmentation of biopolymers, hence supporting the biodegradable nature of PFA-based biopolymer.

Fracture morphology and mechanical properties of blisters in poly- and single crystal tungsten irradiated by MeV protons

The mechanical properties and the fracture morphology of the inner surface of blisters formed in polycrystalline and single crystal tungsten under MeV proton irradiation, were studied.The tungsten samples were irradiated at Soreq Applied Research Accelerator Facility (SARAF) by 2.2 MeV protons, at various samples temperatures and proton doses. The morphology of the irradiated samples was observed by examining cross sections of blisters obtained by focused ion beam (FIB). The thickness of the blister cap was found to be in good agreement with the irradiating protons stopping range, regardless of sample structure, temperature or total dose. Increased curvature of the surfaces was observed with increased temperature for polycrystalline and single crystal blisters and was interpreted as increased ductility of the blister growth process. The ductility is more substantial in single crystal blisters, pointing to the role of grain boundaries in blisters growth mechanism. The cap of one blister was removed, exposing the inner fracture surface of a blister and supporting the validity of the cross sectional observations.The mechanical properties in the vicinity of a blister formed in a single crystal sample were characterized by nano-indentation. The hardness near the irradiated surface was found to increase both in the vicinity of the blister and beyond. This observation suggests that the elevation of the blister cap does not cause significant strain hardening. For the blister cap, the hardness was found to increase with increasing depth from the irradiated surface, correlating with increased irradiation damage.

Properties of Blisters Formed on Polymer Films and Differentiating them from Nanobubbles/Nanodrops.

When studying surface nanobubbles on film-coated substrates, a class of bubble-like domains called blisters are probably forming at the solid-liquid interface together with nanobubbles. This may easily lead to a misunderstanding of the characteristics and applications of surface nanobubbles and thus continue to cause problems within the nanobubble community. Therefore, how to distinguish surface nanobubbles from blisters is a problem. Herein, the morphology and properties of blisters are investigated on both smooth and nanopitted polystyrene (PS) films in degassed water. The morphology and contact angle of blisters are similar to those of surface nanobubbles. However, blisters were observed to be punctured under the tip-blister interaction and be torn broken by an atomic force microscope tip during the process of scanning. At the same time, nanopits on the surface of blisters that formed on a pitted PS film can be seen clearly. These provide direct and visual evidence for distinguishing blisters from surface nanobubbles. In addition, surface nanobubbles and blisters on smooth and pitted PS films in air-equilibrated water are studied. No punctured surface nanobubble was observed, and the force curves obtained on surface nanobubbles and the change in height of blisters and surface nanobubbles under a large scanning force show that surface nanobubbles are much softer than blisters.

Pénfigo Vulgar y Lupus Eritematoso Sistémico. Reporte de caso

El Lupus Eritematoso sistémico (LES) es una enfermedad autoinmunitaria, multisistémica y episódica, caracterizada por la inflamación vascular generalizada y del tejido conectivo, además por la presencia de anticuerpos antinucleares (ANA) y anticuerpos anti-DNA de doble cadena. El término pénfigo; enfermedad ampollar poco frecuente, de etiología autoinmune, que afecta la piel y mucosas. Define un grupo de enfermedades autoinmunes de la piel caracterizadas por la presencia de inmunoglobulina G (IgG) dirigida a la superficie de los queratinocitos y ampollas debidas a acantólisis (separación intercelular). Paciente femenina de 16 años de edad, con historia de presentar edema en rodilla derecha, manos y pies acompañada de artralgias de un año de evolución. Además, dificultad para la deambulación de 3 días de evolución. Presentó lesiones ampollosas en mucosa oral y labio superior confluyentes y se extienden a piel circundante. Las articulaciones metacarpofalángicas de manos estaban edematizadas, dolorosas, con leve deformidad y limitación funcional. Lasampollas inicialmente localizadas en cara y extremidades inferiores se fueron extendiendo a miembros inferiores, acompañado de eritema palmar bilateral. Se le diagnosticó Pénfigo Vulgar y Lupus Eritematoso Sistémico. Este último, por presentar criterios laboratoriales compatibles con LES: leucopenia, ANA positivo, nefropatía y artritis. Se inició tratamiento con prednisona 50 mg vía oral cada día (1 mg/kg/día). Palabras clave Enfermedades Autoinmunes, Lupus Eritematoso Sistémico, Péngo

Laser-driven high-frequency vibrations of metal blister surface

Time-resolved interferometric microscopy was applied to investigate laser-induced blistering of a titanium film on a silica substrate. Ablation of the titanium/silica interface by single 0.7 ns pulses within a certain fluence range results in local exfoliation of the metal film from the substrate avoiding, however, complete film destruction. Time-dependent transformation of the metal surface profile was reconstructed from the interference patterns within 0–13 ns time delay range. Transverse annular waves with typical amplitude of one hundred of nanometers and estimated traveling speed of few kilometers per second were revealed on the blister surface. The wave occurrence was attributed to fast inhomogeneous bending of the film covering the expanding blister. The resultant high-frequency (∼1 GHz) vibrations of the metal surface provide intensive inertial forces when such metalized target is used for blister-based laser-induced forward transfer of nanopowders and organic molecules.

MIXING CHARACTERISTICS OF RICE BY TRACER TECHNIQUE IN AN AGITATED CYLINDRICAL PRECONDITIONER DEVELOPED FOR PUFFED RICE PRODUCTION SYSTEM

ABSTRACTUniform heating and drying of salt‐solution diffused rice grain (preconditioning) is an essential prerequisite for obtaining good puffing quality of rice when roasted on hot sand bed or in hot air. Possibility of uniform heating of rice grains inside an externally heated agitated cylindrical vessel (developed mechanized rice preconditioner) has been concluded by estimating the mixing indices using tracer grain technique. Effects of initial positions (top, middle and bottom layers in the bed moisture contents [15.59 ± 0.88, 20.34 ± 0.68, 25.30 ± 0.77, 29.78 ± 0.27% wet basis] and mass [50, 100 and 200 g] of the tracer grains) on mixing indices have been studied while agitation continued up to 90 min at 12 ± 2 rpm. The mixing indices with the designed agitated system attained the maximum value of about 1.0 (i.e., uniform distribution of tracer particles throughout the bed) within 5 min and remained almost unaltered thereafter up to 90 min of mixing. Sample size of the tracer or its initial position on the bed showed no significant change on the mixing trends, and uniform distribution of tracer grains at different locations along vertical and lateral directions in the bed have been observed for the entire period of mixing. Moisture contents did not show any effect on the mixing behavior of the grains in the bed.PRACTICAL APPLICATIONSImportance of preconditioning of rice before puffing is fully recognized by various authors to produce good quality puffed rice. This is a slow and uniform heating process of the grains. But, this is usually practiced traditionally by soaking the parboiled milled rice with water, adding 2.5–5.0% common salt, tempering for about 6–8 h for diffusion of salt and moisture into the kernel, and following it by slow heating (70–90C). Uniform heating of the grains are a major prerequisite as nonuniform heating of grain at this stage severely impairs the quality of product with less expansion ratio in addition to rough and blistered surface. Besides, traditional method of production of puffed rice is a tedious and laborious process which can easily be replaced by a mechanical system to increase the quantum of production, decrease the cost and improve the quality of the product through uniform heat and mass transfer in the grain. The uniform heat and mass transfer in the grains can be ensured by providing continuous agitating system to constantly turn the grains and expose each grain to the contact of the heated surface. Therefore, conducting mixing study of the rice grains inside an agitated cylindrical vessel will be very much useful in order to ascertain whether conditioning of grain is proper by uniform and thorough mixing of grains and uniform exposure to heat. This study will have further practical implications in designing and development of a proper mixing system for commercial production of good quality puffed rice.

Investigation of the influence of textiles and surface treatments on blistering using a novel simulant

Friction blisters occur when shear loading causes the separation of dermal layers. Consequences range from minor pain to life-threatening infection. Past research in blister formation has focused on in vivo experiments, which complicate a mechanics-based study of the phenomenon. A Synthetic Skin Simulant Platform (3SP) approach was developed to investigate the effect of textile fabrics (t-shirt knit and denim cottons) and surface treatments (dry and wet lubricants) on blister formation. 3SP samples consist of bonded elastomeric layers that are surrogates for various dermal layers. These layers display frictional and mechanical properties similar to their anatomical analogues. Blistering was assessed by the measurement of deboned area between layers. Denim caused greater blistering than did the t-shirt knit cotton, and both lubricants significantly reduced blister area and surface damage. A triglyceride-based lubricant had a more pronounced effect on blister reduction than corn starch. The triglyceride lubricant used with t-shirt knit cotton resulted in no blisters being formed. The performance of the 3SP approach follows previously reported frictional behavior of skin in vivo. The results of textile and surface treatment performance suggest that future 3SP iterations can be focused on specific anatomical sites based on application type.

Study on effect of filler loading on the flow and swelling behaviors of polypropylene‐kaolin composites using single‐screw extruder

AbstractMelt flow and extrudate swelling behavior of polypropylene‐kaolin (PP‐Kaolin) composites were investigated using a single‐screw extruder. Kaolin was mixed with polypropylene (PP) using a heated two‐roll mill at 185°C and the filler loading were varied from 5 to 30 wt %. Subsequently, flow behavior of the compounded formulations were evaluated through Melt Flow Index (MFI) measurement at various temperatures ranging from 190 to 230°C. The extrudate swelling ratio was also measured by using an image analysis instrument and software. It was proven that the MFI decreased with increasing loading of kaolin for test temperatures of 190 and 200°C. However, for temperatures exceeding 200°C, the MFI value rose slightly at 5 wt % of kaolin content then seemed to reduce as more kaolin was added. This is also detected in rheological measurement where the apparent visosity, ηapp, appear to be lowered at 5 wt % loading of kaolin. Further increase in kaolin loading resulted in increasing value of the composites ηapp. The swelling ratio decrease with increasing filler loading for composites below 20 wt %. However, at 30 wt % of kaolin content, the extrudate swelling ratio increased and noticeable blistered surface texture was observed on the extrudate surface. Furthermore, at this level of filler loading, shrinkage occurence due to the existence thermal gradient between the surface and the inner core of the extrudate caused void formation in the middle section of the extrudate. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Surface Patterning Using Blister Exfoliation Induced by Electron Irradiation

The exfoliation of surface blisters was investigated as a candidate for a novel surface patterning method. Surface blisters were prepared by H ion implantation into a Si(100) surface. After blister formation, the surface was oxidized. The oxidized blistered surface was irradiated using a focused electron beam. Electron irradiation for 10 min. at an insident energy of 5 keV caused the exfoliation of the blisters. Local exfoliation of the oxidized blistered surface allowed surface patterning of both the bare and oxidized surfaces; that is, the patterning of both Si and Si oxide. This technique thus makes it possible to fabricate surface patterns.

High-Z Dust Generation on Tungsten Surfaces due to Synergetic Erosion of Deuterium/Helium Plasma Exposures

Low-energy and high-flux plasma exposures on tungsten surfaces result in blister/hole formation. Subsequent He plasma exposure at 2,000 K on the blister-rich surface forms a hole structure on the surface, including the blister surface, and some blisters collapse due to recrystallization and bubble formation on the blister skin. Grain ejections were observed after deuterium plasma exposure at 550 K on a W surface on which a hole structure had formed due to He pre-exposure at 1,600 K.

Transmission electron microscopy study of blisters in high-temperature annealed He and H co-implanted single-crystal silicon

Transmission electron microscopy has allowed us to draw the three-dimensional structure of blisters formed after high-temperature annealing of He-H co-implanted silicon by combining the unique capability of site-selective cross sectioning of the focused ion beam with conventional plan view images. It has been shown that blisters are formed by crystalline lamellae strongly bended, plastically deformed, and suspended over buried empty cavities. The volume of the protruding blister surface is almost equal to the buried empty volumes, thus suggesting a mechanism for blister formation based on H and He precipitation and migration of silicon atoms toward the surface.

The role of different surface damages in corrosion process in alkaline sour media

By applying different electrochemical methodologies to 1018 carbon steel/different electrolytic media interfaces, surfaces with generalised and blistered damages, commonly present in the oil refinery catalytic plants, were obtained. Afterwards, a freshly polished carbon steel surface as well as the damaged surfaces were characterised by electrochemical impedance spectroscopy and scanning electronic microscopy (SEM). The SEM results reveal that the damaged surfaces present films with different physical properties. In spite of the surface modification, the corrosion mechanism of these interfaces in a medium simulating catalytic plants condensates of the refineries in Mexico (0.1 M (NH 4) 2S, 0.4 mM NaCN (10 ppm CN −), pH=8.8) turned out to be the same. It was also found that the corrosion process presents the following steps: charge transfer resistance of steel oxidation in the metal/corrosion product film interface and the diffusion processes of Fe 2+ and H o ions through the corrosion product film. It was demonstrated that when there was no damage on the surface (freshly polished surface), a homogeneous film was formed instantaneously upon introducing carbon steel into the sour media. The corrosion process in this film occurs in three stages. On the surface with generalised corrosion the three stages are favoured, particularly that of atomic hydrogen process (inducing blistering). Meanwhile, the blistered surface presents a higher charge resistance of steel oxidation and the Fe 2+ and atomic hydrogen diffusions through the corrosion products are slower than those presented on the other surface states.

Friction and wear of nitrogen-implanted glassy carbon

Scratch friction and wear behavior of a glassy carbon (GC) implanted with a high dose of nitrogen as studied when in contact with a steel ball and with diamond indenter. A sliding velocity of V = 0.2 mm s −1 and loads from 0.5 to 4 N during 50–300 cycles were applied in laboratory air (humidity ~50%). Smoother and more closely compacted surfaces than in the virgin state were obtained at doses of 1 × 10 16–1 × 10 17 ions cm −2, but surfaces became heavily blistered at higher ion dose levels (1–1.5 × 10 18 ions cm −2). It was shown that the enhancement of wear resistance is associated with the amorphization of the implanted layer, which leads to a rise in strength of implanted GC and to a decrease in the rate of crack propagation in a hostile environment. Crescent-shaped cracks were observed on the surface of virgin GC subjected to friction with a steel ball. At higher doses of implantation, steel wear particles adhered to the rough blistered surface in contact with the steel ball, and bubbles burst following contact with the diamond indenter. The implant dosage needed for maximum wear resistance was found to be in the vicinity of 1 × 10 16 ions cm −2. The influence of the gradual change in the bonding mode with the of implantation dosage (from sp 2, characteristic for graphite and GC, to sp 3, characteristic for diamond) on the tribological properties of the carbon materials is discussed. The synergetic influence of implantation and environmental humidity was adduced to explain the observed behavior of GC in friction and wear.

An electron microscopic study of clinical and laboratory-derived strains of teicoplanin-resistant Staphylococcus haemolyticus.

Staphylococcal resistance to glycopeptides (which involves more teicoplanin than vancomycin) is uncommon and largely confined to Staphylococcus haemolyticus, an emerging nosocomial pathogen with a tendency to develop antibiotic resistance. In this study, six S. haemolyticus strains, including two isogenic pairs of teicoplanin-susceptible/-resistant strains and two resistant clinical isolates, were used in a morphologic and morphometric electron microscope investigation. Cells from both clinical and laboratory-derived teicoplanin-resistant strains exhibited abnormally roughened, irregular outlines when observed by transmission electron microscopy. However, no significant differences in cell wall thickness resulted from morphometric analysis when the susceptible/resistant cells of the two isogenic pairs were compared. By scanning electron microscopy, an abnormally roughened, blistered surface was associated with teicoplanin-resistant cocci. A certain variability was noted between strains, not clearly related to the resistance level. In freeze-fracture investigations, a higher number per square micrometer of intramembrane particles, more significant in the E than in the P membrane fracture face, was observed in the laboratory-derived resistant clones as compared to susceptible parent strains. Further studies are needed to understand the cause-effect relation between these ultrastructural alterations and staphylococcal resistance to teicoplanin (but not to vancomycin).

Synergistic effects between helium and hydrogen isotopes on gas detrapping in polycrystalline nickel

The thermal desorption and SEM techniques have been used to study the effects of the presence of deuterium and hydrogen atoms on the retention of implanted helium in polycrystalline nickel. For samples pre-implanted with 40 keV helium to a dose of 1 × 10 21 ions/ m 2 the ratio of trapped deuterium atoms to the implanted helium was found to be about 0.4 D/He and an effective trapping energy ~ 0.5 eV was found. For samples pre-implanted with 10 keV He to doses from 1.5 × 10 21 to 4 × 10 21 ions/ m 2, low temperature helium release stages were observed, and resulted in a decrease of deuterium trapping efficiency to as low as 0.0075 D/He. Both deuterium and hydrogen charging were found to enhance the helium release and to decrease the release temperature. For the high dose samples, deuterium or hydrogen gas charging and thermal desorption were also found to induce blister growth and surface exfoliation.

Evaluation of the effect of azapropazone on neutrophil migration in anaesthetized swine using a multichamber blister suction technique

1. The purpose of this study was to determine the in vivo inhibitory efficacy of azapropazone on neutrophil migration. The effects of azapropazone given at a dose of 100 mg kg-1 i.v. every 2 h on the neutrophil migration into skin inflammation sites (blister fluid) as well as into an autologous serum (+/- chemoattractant) placed above the blister surface (2nd chamber) were determined. 2. Azapropazone treatment schedule maintained blood levels at 70-100 micrograms ml-1 throughout the time course (360 min) of the experiment. 3. Azapropazone significantly inhibited (48 +/- 6%) neutrophil migration into the blister fluid (as evident from the decrease in myeloperoxidase activity). 4. Azapropazone significantly inhibited the neutrophil migration into the autologous serum either with (65 +/- 5%) or (35 +/- 6%) without the chemoattractant, formyl-methionyl-leucyl-phenylalanine (FMLP). The chemoattractant, FMLP, markedly increased neutrophil migration into the autologous serum by approximately 1.5 to 2 times the non-FMLP treated group. Azapropazone was more efficacious in inhibiting the neutrophil migration in the presence of FMLP than in its absence. 5. We conclude that azapropazone is an effective inhibitor of neutrophil migration into topically inflamed sites in anaesthetized swine.

Formation of blisters in molybdenum bombarded with helium

THE formation of surface blisters on metals bombarded with low energy inert gas ions was first observed by Primak1 but only recently, when the potential importance of blistering in the first wall of a fusion reactor became recognised, has much further attention been paid to the phenomenon2,3. Most of this work has used scanning electron microscopy to examine the blistered surface although considerable information has also been obtained from gas release measurements both during bombardment and in post-bombardment anneals. Transmission electron microscopy has been used to a lesser extent but nevertheless has yielded important information on the substructure within the layer where the gas atoms came to rest—normally some hundreds of Angstroms from the metal surface. For example, several workers have shown that gas bubbles form in thin foils irradiated with low energy (<300 keV) helium or argon ions4–6. One interesting fact (D. J. Mazey, unpublished) is that over a wide temperature range from 600 °C down to 20 °C, 36 keV helium bombardment of molybdenum produces a fine distribution of helium bubbles crystallising on to a body-centred-cubic (b.c.c.) lattice analogous to the void lattice4,7. Here I describe an extension of transmission microscopy to view the blisters themselves and suggest some details of the blister formation mechanism.

Rates of transfer of Rb 86, K 42, K 39, Cl 36, Cl 35, Na 22, and Na 23 across a blister surface on the forearm of normal man and patients with chronic congestive heart failure

The base of a cantharides blister on the forearm of man was utilized as a living membrane for the study of kinetics of electrolyte transfer. This preparation provided a readily reproducible and reliable model for such studies. Studies were made of transfer of Na 23, Na 22, Cl 35, Cl 36, K 39, K 42 and Rb 86 both into and out of the experimental extracorporeal compartment. Since the electrolytes and radioisotopes entered and left the extracorporeal compartment by way of capillaries, this model provided an approach to the study of transfer across capillary walls without the limitations of circulation and mixing which interfere with such studies from within the vascular tree. Transcapillary transfer of electrolytes was found to be very rapid. Estimation of the amount of electrolytes crossing the capillaries of man per day revealed enormous amounts: sodium chloride 60,000 lb and potassium 1900 lb at normal seral concentrations.