Appearance Of Pits Research Articles

Hierarchical Significance of Environment Impact Factor on the Sand Erosion Performance of Lightweight Alloys.

This paper addresses the challenge of ranking the factors that affect the erosion resistance of lightweight alloys, with a specific focus on aluminum alloys. A three-factor, four-level orthogonal experimental design was employed to examine the influence of various sand particle sizes, erosion speeds, and sand concentrations on the abrasion qualities of these alloys. Parameters such as mass loss, depth, residual stresses, and failure mechanisms were assessed to determine erosion performance. Analysis of variance (ANOVA) and regression analysis of the three key factors were performed. Our findings resulted in an erosion rate formula: erosion rate = 0.679 sand particle size +0.067 sand concentration -0.002 erosion velocity +0.285. Our findings indicate that particle size is the most significant factor affecting erosion rate, with sand concentration and erosion velocity being secondary factors. The failure mechanism reveals that larger sand particles tend to produce deeper slides, and higher sand concentrations result in an increased number of slides. A lower concentration leads to the appearance of erosion pits. And the test conditions of high concentration and low velocity lead to more serious brittle fractures of the substrate, often accompanied by the appearance of cracks.

Gross Morphological and Scanning Electron Microscopic Study of Abomasum of Sheep (Ovis aries) during Pre-natal Life

Background: The enzymatic digestion occurs in the abomasum of sheep. A systematic comprehensive study on the embryogenesis of abomasums of sheep is lacking due to availability of sporadic information in current literature. So the current research was designed to explain the detail gross ontogenic occurrences along with scanning electron microscopic study of abomasum in sheep. Methods: From the local slaughter house, 12 healthy sheep foeti of non-descript breed were gathered and grouped into Group I (early pregnancy), Group II (mid pregnancy) and Group III (late pregnancy) having 04 foeti in every group. The abdomen of the foetus was incised and opened. The stomach was exposed and the gross observations were recorded. Then tissue samples from the abomasum were processed for scanning electron microscopic study. Result: The abomasums assumed comma shape at the gestational age of 32 to 48 days. At 67 days of foetus, the external constriction between fundus and pylorus of the abomasum was observed distinctly. In foeti of 32 to 48 days age, it was present between 13th rib and 1st lumbar vertebra. This topography changed to 8th rib and 3rd lumbar vertebra by 121 days of foetal age. The outline of the abomasal folds were noted first at 32 days of age. The height of the abomasal folds in fundus was larger than pylorus. The appearance of gastric pits on the mucosal surface was first observed at 63 days of gestation through scanning electron microscope.

Laser Cladding of Layered Ti/Nb/Cu Cathode with Homogeneous Arc Ablation Behaviors

Arc ablation threatens the cathode operating time and restricts the development of high‐power arc heaters. Surface modification is an effective strategy in improving cathode ablation resistance without reducing matrix conductivities. Herein, Nb layer and Ti layer are laser clad on Cu matrix to decrease the arc ablation of Cu cathode. The total thickness of laser‐clad Nb/Ti layer reaches 1850 μm. The Nb layer restrains Cu from diluting into surface cladding and no detrimental Ti–Cu intermetallic is formed. The surface Ti content is as high as 98.34 at%, guaranteeing the arc discharge homogeneity. The arc ablation behaviors of Ti/Nb/Cu cathodes are investigated in air atmosphere. The layered cathode discharges and ablates homogeneously. The arc discharge center is shallow with no appearance of deep pits or craters. The maximum ablation depth (72.1 μm) after 30 s discharging is ≈33.4% lower than that of Cu cathode. Besides, the cathode ablation rate, 1.61 μg C−1, is ≈27.5% lower than Cu cathode. The improved arc ablation resistance is interpreted in the protective effect of refractory TiO2 layer formed during air arc discharging.

Effect of Implantoplasty on Roughness, Fatigue and Corrosion Behavior of Narrow Diameter Dental Implants.

Implantoplasty (IP) is used in dental implants with peri-implantitis and aims to remove threads and polish rough surfaces in order to prevent bacterial colonization. As a result of this procedure, implant strength might be compromised. We tested 20 tapered screw-shaped Ti6Al4V dental implants with a simulated bone loss of 50%. Ten implants underwent IP and 10 served as controls. Surface topography (Sa, Sz, Ssk, and Sdr) was analyzed with a confocal optical microscope. Subsequently, a minimum of four series of cyclic loads were applied with a servo-hydraulic mechanical testing machine (5 × 106 cycles at 15 Hz, between a maximal nominal value-starting at 529 N in the IP group and 735 N in the control group-and 10% of that force). We recorded the number of cycles until failure and the type of failure. Implant failure was analyzed by visual inspection and scanning electron microscopy. Open circuit potential and potenctiodynamic tests were carried out with high precision potentiostat using Hank's solution at 37 °C to evaluate the effect of the implantoplasty on the corrosion resistance. Implantoplasty significantly reduced the surface topography values (median) and interquartile range (IQR); Sa from 1.76 (IQR = 0.11) to 0.49 (IQR = 0.16), Sz from 20.98 (IQR = 8.14) to 8.19 (IQR = 4.16), Ssk from 0.01 (IQR = 0.34) to -0.74 (IQR = 0.53) and Sdr from 18.20 (IQR = 2.26) to 2.67 (IQR = 0.87). The fatigue limits of the control and implantoplasty groups were 551 N and 529 N, respectively. The scanning electron micrographs showed fatigue striations indicating fatigue failure. Besides, the fractographic analysis revealed a typical brittle intergranular fracture mechanism. The infinite life range of the dental implants evaluated was largely above the threshold of usual chewing forces. Implantoplasty seems to render a fairly smooth surface and has a limited impact on fatigue resistance. In addition, implantoplasty produces a decrease in the corrosion resistance of the implant. Corrosion current density from 0.019 μA/cm2 for as-received to 0.069 μA/cm2 in the interface smooth-roughened dental implant. These places between the machining and the rough area of the implant are the most susceptible, with the appearance of pitting.

In-situ Investigation of the Onset of Cavitation Damage from Single Bubbles on Technical Alloys

Cavitation erosion is typically studied with ultrasonic sonotrodes. Only a few attempts have been made to study cavitation erosion of technical alloys on the level of repeated single bubbles. Such single cavitation bubbles can be induced by a focused laser pulse with high spatio-temporal repeatability. In this work, the surface damage caused by series of laser-induced single bubbles in water is observed with a light microscope in-situ between two successive bubbles. Polished samples from pure aluminum, an austenitic steel (316L, X2CrNiMo18-15-3), and a nickel aluminum bronze (CuAl10Ni5Fe5) were subjected to series of bubbles that typically had a maximum diameter of d = 2.5 mm and a non-dimensional stand-off distance γ = 1.4. Via in-situ microscopy, the appearance of individual pits can be assigned to a specific, single bubble collapse event without removing the sample. Consistent with literature, for the chosen parameters the damaged region after many bubbles is circular, with individual pits that are deeper for aluminum than for the bronze and the steel. Additionally, our findings suggest that even high-strength materials can be damaged by the impact of just one single bubble, while not every single bubble causes a pit on the soft aluminum. From series of images after each bubble, the rate of pit accumulation was determined to be 2.6 pits/bubble for aluminum and around 0.3–0.5 pits/bubble for the two technical alloys.

Potential of fruit pits as aggregate in concrete

• Research of potential utilization of cherry/grapepits as aggregate in concrete. • Complete replacement of coarse/fine aggregate in concrete with cherry/grape pits. • Alkali solution treatment of pits to improve adhesion between pits and cement paste. • Testing the mechanical and thermal characteristics of concrete. • Pit aggregate decrease thermal conductivity of concrete. Most of the research dealing with the use of agro-waste as concrete aggregate implement agro-waste as a partial replacement of fine/coarse aggregate without any prior treatment of its surface. This paper investigates the influence of the complete replacement of fine/coarse aggregate with fruit pits (grape or cherry pits) on the properties of hardened concrete. The pits were used as untreated and treated with alkali solutions (2.5 % and 5 % NaOH). For untreated and treated pits, CHNS analysis was carried out while surface properties were detected by a digital microscope, Brunauer-Emmett-Teller (BET) method and computed tomography. There were no differences observed in the elemental composition between untreated and alkali treated pits. Both alkali solutions improved surface appearance of cherry pits but influenced negatively their integrity. In the case of grape pits, both concentrations had a devastating effect on their inner and outer structure. The compressive strength and the density, of the hardened concrete samples prepared with untreated and alkali treated pits, were measured according to the relevant European standards while the thermal conductivity was measured according to ISO standard. Replacing the aggregate with fruit pits decreased the density, influenced the compressive strength negatively and also reduced thermal conductivity of concrete, which results in a reduction of heat transfer and energy consumption of buildings.

HISTOGENESIS OF HUMAN FETAL STOMACH AT VARIOUS GESTATIONAL AGES – AN OBSERVATIONAL STUDY

Objective: Knowledge on timelines of structural and histological development of fetal stomach helps in the diagnosis of abnormalities (duplication cyst of the pylorus, heterotopic pancreatic tissue, etc.,) and weighing interventions as an option. The present study was undertaken to establish the timelines of the developmental process of stomach (e.g., appearance of curvatures, gastric pit, gastric glands, and various cell types) correlating with the gestational age. Methods: Fifty normal, aborted and unclaimed fetuses were obtained from local private and government hospitals observing all formalities. The tissues of 3–5 mm thickness were taken and preserved in 10% formalin for 72 h, followed by tissue processing and staining with hematoxylin eosin and periodic acid Schiff and observations were made under microscope. Results: Lesser and greater curvatures appeared in the first trimester. All the four layers and gastric pits were observed at 16th week, cuboidal epithelium turns columnar and nidus of gastric glands, circular muscular layer submucuosa noted by 18th week, longitudinal layer of muscle appeared at 20th week, parietal, zymogenand mucus neck cells observed by 24th week in fundus, and body oblique muscle was evident by 28th week and near adult pattern seen by 32nd week of gestation. Conclusion: From the available literature, very few studies have reported regarding histogenesis of human fetal stomach in India. The present study is one such to supplement the known data and knowledge regarding histogenesis of human fetal stomach and help in diagnosis and treatment of related congenital anomalies.

Evolution of the Geometric Structure of X39Cr13 Steel upon Thermochemical Treatment Specific to Medical-Grade Steels

This paper presents the results of the multi-aspect surface characterization of X39Cr13 steel samples subjected to technological processes specific to medical instrumentation, such as heat and thermochemical treatment, as well as sterilization, which are implemented in corrosion resistance measurements. The application of numerical methods of fractal analysis to averaged profiles obtained from SEM images resulted in double-log plots of structure function, from which the determination of the fractal parameters of interest was possible. The discussion was focused on the fractal dimension D, which governs relative height variations upon scaling in length, and corner frequency fc, which separates the scaling behavior of different-order structures (particles and their aggregates). The obtained results show that the heat treatment leaves behind a granular structure of steel (D2 = 2.43; fc2 = 1.97 nm), whereas corrosion tests reveal the appearance of pits (D1 = 2.17; fc1 = 0.303 nm; D2 = 2.59; fc2 = 4.76 nm). In turn, the ion nitriding improves the resistance of steel X39Cr13 to local corrosion. The fractal analysis also shows that the structure of the nitrided layer differs insignificantly from that of the untreated material, seen only as a shortening of the radius of the self-similarity area by a factor of two (fc2 = 1 nm).

Understanding Consequences and Tradeoffs of Melt Processing as a Pretreatment for Enzymatic Depolymerization of Poly(ethylene terephthalate).

Melt extrusion pretreatment of poly(ethylene terephthalate) (PET) prior to enzymatic depolymerization with an unpurified leaf branch compost cutinase enzyme cocktail is explored to ascertain the efficiency gained by different processing methods on the enzymatic depolymerization of PET. Specific surface area (SSA) is investigated as a key factor in reducing depolymerization time. Higher SSA substrates (>5.6mm2 mg-1 ) show higher depolymerization rates (≈0.88gL-1 terephthalic acid [TPA] per day) and no induction phase, while lower SSA substrates (≈4.3, 4.4, and 5.6mm2 mg-1 ) show, after an initial induction phase, similar depolymerization rates (≈0.46, 0.45, and 0.44gL-1 TPA per day) despite increases in SSA of up to 30%. The mechanism of enzymatic depolymerization manifests in the appearance of anisotropic pitting. Longer incubation time used to overcome the induction phase in low SSA substrates allows for nearly full recovery of monomeric products, but manual pregrinding of extruded PET sharply increases SSA, depolymerization rate, and substrate crystallinity which may decrease the maximum recycled yield of the product materials. An estimate of the energy cost of increasing SSA is made and its effects on material properties are discussed. This work highlights key material structure and pretreatment aspects influencing the enzymatic recycling of PET.

Micro-action mechanism and macro-prediction analysis in the process of CO2 huff-n-puff in ultra-heavy oil reservoirs

Aiming at the problem of the unclear microscopic interaction mechanisms between carbon dioxide (CO2) and reservoir rocks and fluids during CO2 huff-n-puff in ultra-heavy oil reservoirs. In this study, scanning electron microscope (SEM) and visual displacement experiment were used to understand the mechanisms among them. Then, the interaction experiment and numerical simulation between CO2 and heavy oil were carried out to verify the feasibility of CO2 huff-n-puff to improve the recovery of ultra-heavy oil reservoirs. The results showed that: a) Within a certain range of pressure, the corrosion ability of carbonated water formed by CO2 and formation water gradually increased as pressure increased. When the pressure increased from 6 MPa to 12 MPa, the average corrosion rate increased from 0.36% to 0.49%. b) CO2 can effectively improve the pore structure and permeability of rocks. The injection of CO2 caused hydration expansion, surface particle peeled off, deepening of depression, the appearance of corrosion pits and cracks, and cracks extending as pressure increased. Under the pressure of 6 MPa and 12 MPa, the permeability increased by 14.67% and 41.86%, respectively. c) CO2 injection made the heavy oil form amount of dispersed secondary foam oil, which greatly reduced the viscosity of crude oil and increased the expansion ability of heavy oil. When the pressure increased to 12 MPa, the volume coefficient and viscosity reduction rate reached 1.18 and 99.62%. d) The displacement experiment demonstrated that the displacement efficiency of CO2 was 23.09% higher than water flooding. e) According to the results of numerical simulation, during five cycles of CO2 huff-n-puff, the reservoir pressure rose from 3481 KPa at the end of depletion production to 6187 KPa, which showed that pressure was effectively maintained; The viscosity of the heavy oil decreased from 12825cp to 3280.49cp, and the 10-year recovery factor was 13.08%. The understanding of the micro-action mechanism could have certain guiding significance for improving the development effect of CO2 huff-n-puff in the ultra-heavy oil reservoirs.

Evolution of corrosion on microstructure of ceramic coating produced by plasma electrolytic oxidation in molten salt

Low corrosion resistance in an Al alloy is usually overcome with the help of an Al oxide coating. Plasma electrolytic oxidation (PEO) is a highly promising environment-friendly method to achieve a ceramic surface. Traditionally, PEO is carried out in an aqueous electrolyte; however, in this study, PEO was conducted in a molten salt. This approach conserved more energy and led the formation of a pure oxide coating, as confirmed by subsequent phase analysis. The obtained ceramic coating contained two sublayers: a porous outer sublayer and a dense inner sublayer. A study of corrosion evolution was performed on oxide-coated alloys immersed in a NaCl solution for different durations. The corrosion behavior characterized by electrochemical impedance spectroscopy (EIS) was related to the changes in the surface morphology changes examined by electron microscopy. The appearance of pits on the oxide surface was attributed to the adsorption and incorporation theory, previously described for Al alloys. This study revealed that the progress of the corrosion attack by chloride ions affects both sublayers; the thickness of the outer sublayer decreased, and the inner sublayer became more compact, resulting in high resistance properties.

Synergistic effect of Zr addition and grain refinement on corrosion resistance and pitting corrosion behavior of single α-phase Ti-Zr-based alloys

The synergistic effect of Zr addition and grain refinement on the corrosion resistance and pitting corrosion behavior of single α-phase Ti-Zr-based alloys was evaluated. The corrosion mechanisms of as-cast and hot-rolled Ti-xZr-4Al-0.005B alloys (x = 0, 10, 20, 30, 40 wt%) in 5 M aqueous hydrochloric acid solution are investigated by analyzing their electrochemical and immersion corrosion behavior using scanning electron microscopy, electrochemical analyses, and X-ray photoelectron spectroscopy. Both Zr alloying and grain refinement improve the corrosion resistance; while grain refinement improves the stability of the passivation film, Zr addition increases the pitting sensitivity. Zr alloying and grain refinement greatly affects the pitting corrosion behavior in the alloy. In Ti or Ti-Zr alloys with low Zr content, grain refinement inhibits the appearance of corrosion pits inside the grains. For Ti-Zr alloys with higher Zr content, grain refinement induces small corrosion pits in the alloy. Grain refinement increases the frequency of corrosion pits in the Ti-Zr alloys with higher Zr content but inhibits the growth of the pits by improving the corrosion resistance and stability of the passivation film through the formation of more high-valence oxides and a thicker passivation film.

Exploring the influence of electron beam crosslinking in SEBS/TPU and SEBS‐g‐MA/TPU thermoplastic elastomer blends

AbstractThe effects of electron beam (EB) radiation in thermoplastic elastomers based on SEBS/TPU and SEBS‐g‐MA/TPU are evaluated. 60/40 blend of both the systems were subjected to EB using an ILU type industrial accelerator. Radiation dose was varied from 0 to 100 kGy, and the sol–gel content evaluation along with detailed analysis of mechanical, thermal, rheological, and morphological implications was conducted. The interplay between crosslinking and chain scission was quantified using the Charlesby‐Pinner equation. Both the blends showed the presence of a three‐dimensional cross‐linked network in them after the irradiation. The tensile strength of SEBS/TPU was found to deteriorate with an increase in radiation dose, but an opposite trend was observed in SEBS‐g‐MA/TPU. Improvement in interfacial adhesion between SEBS‐g‐MA and TPU was confirmed. The morphological analysis through atomic force microscopy and scanning electron microscopy clearly showed the appearance of rough ridges and pits due to irradiation along with the cross‐linked networks. From differential scanning calorimetry analysis, the changes in glass transitions and melting endotherm were assessed. Thermogravimetric analysis results indicated an improvement in the thermal stability of the blends. The storage modulus and complex viscosity of the samples enhanced as perceived from the rheological measurements. X‐ray diffraction patterns of the blends also showed considerable variation after irradiation.

Cryptic diversity in non-geniculate coralline algae: a new genus Roseolithon (Hapalidiales, Rhodophyta) and seven new species from the Western Atlantic

ABSTRACT Molecular studies have revealed cryptic diversity and polyphyly in the genus Lithothamnion. In this study we aimed to investigate the diversity and phylogeny of specimens that are morphologically described as Lithothamnion based on extensive collections along the Brazilian coast and an integrative taxonomic approach. Our results led to the proposal of Roseolithon gen. nov. belonging to the subfamily Melobesioideae. This new genus is described from the tropical north-western Atlantic and warm temperate south-western Atlantic specimens, based on phylogenetic analyses of psbA, rbcL-3P, COI-5P and SSU rDNA molecular markers, species delimitation methods, genetic divergence and morpho-anatomical observations. The integrative approach led us to find a set of morphological features that characterize Roseolithon: (i) thallus organization monomerous with plumose hypothallus (non-coaxial); (ii) flared epithallial cells; (iii) subepithallial cells varying in size and may be shorter, approximately equal to or longer than those subtending them; (iv) cells of adjacent filaments linked by fusions; (v) tetra/bisporangial conceptacle chambers multiporate; and (vi) the presence of pore canals bordered by rosette cells in depressions giving the surface a pitted appearance. Depending on the species, this pitted appearance occurs due to the sunken or disintegrated rosette cell roofs. The grade of the degeneration of the rosette cell roofs characterizes the species of this genus. The new genus Roseolithon is composed of at least 18 species, of which we describe seven new species: Roseolithon tupii, R. tamoioi, R. tremembei, R. potiguarae, R. karaiborum, R. purii and R. goytacae. Highlights Phylogenetic analyses revealed Lithothamnion to be a polyFphyletic genus. Integrative taxonomy enabled the description of a new genus Roseolithon. Morpho-anatomy does not reflect molecular phylogeny of non-geniculate coralline algae.

Dense VSiCN coatings deposited by filament-assisted reactive magnetron sputtering with varying amorphous phase precursor flow rates

Phase-modulated VSiCN coatings were deposited with hot filament assistance by magnetron sputtering of a vanadium target in a gas mixture of argon, nitrogen, and hexamethyldisilazane (HMDS). HMDS flow conditions and total working pressure were varied to influence coating amorphous phase content (0 at.% ≤ Si ≤ 9 at.%). Scanning electron microscopy revealed that deposition with HMDS vapor disrupted columnar growth and increased coating growth rate by as much as 27% relative to a VN 0.8 reference. Coating surface morphologies were characterized by atomic force microscopy . A transition from a nodular appearance ( R q = 8.9 nm) for the VN 0.8 coating to a pitted appearance ( R q = 2.7 nm) for the coating containing 9 at.% Si was observed. X-ray diffraction analysis and transmission electron microscopy indicated that the VSiCN coatings contained a nanocrystalline B1-VC x N y phase and an amorphous phase, whose phase fraction increased with HMDS flow. The crystallographic out-of-plane preferred orientation of the VN 0.8 coating was (220) while all VSiCN coatings were (111) textured. Coating hardness and apparent elastic modulus were measured by nanoindentation . The VSiCN coating with 3 at.% Si exhibited the highest hardness of 31.4 GPa, which was 8.8 GPa greater than the VN 0.8 coating. Coating apparent elastic modulus decreased with increasing HMDS flow from 288 GPa to 188 GPa. All coatings exhibited excellent adhesion to stainless steel substrates as evaluated by the Rockwell indentation test . The disruption of columnar growth and incorporation of Si in VSiCN coatings is a possible method of improving the high temperature wear resistance of VN-based coatings. • Deposition of dense, non-columnar VSiCN coatings is demonstrated. • Hexamethyldisilazane (HMDS) vapor is used as an amorphous phase precursor. • Granular and pitted surface topographies are obtained with R q < 3 nm. • Coating preferred orientation is (220) for the VN 0.8 reference and (111) for VSiCN. • Hardness decreases from 31 GPa to 19 GPa with increasing amorphous phase content.

Role of Ti and Y in the nucleation of the primary α-Al of Al7075–Ti–Y natural composites and influence of ultrasonic vibration

Abstract Al7075–Ti–Y natural composites were prepared by using a combination of ultrasonic vibration and casting. The effects of titanium (Ti) and yttrium (Y) on the nucleation of primary α-Al were studied and the influencing mechanism of Y on the TiAl3 formation was analysed. Furthermore, a reaction kinetics model of TiAl3 under ultrasonic vibration was established. The results showed that the uniformly distributed TiAl3 and Al3Y nano-particles resulted in grain refinement. Y changed the morphology of TiAl3 and the appearance of corrosion pits was related to the fact that Y was dissolved within the TiAl3 structure to form Ti(Al,Y)3. The established model revealed that ultrasonic vibration significantly promoted the formation of TiAl3, and that ultrasonic time was the main factor affecting its growth.

Role of Ti and Y in the nucleation of the primary α-Al of Al7075–Ti–Y natural composites and influence of ultrasonic vibration

Abstract Al7075–Ti–Y natural composites were prepared by using a combination of ultrasonic vibration and casting. The effects of titanium (Ti) and yttrium (Y) on the nucleation of primary α-Al were studied and the influencing mechanism of Y on the TiAl3 formation was analysed. Furthermore, a reaction kinetics model of TiAl3 under ultrasonic vibration was established. The results showed that the uniformly distributed TiAl3 and Al3Y nano-particles resulted in grain refinement. Y changed the morphology of TiAl3 and the appearance of corrosion pits was related to the fact that Y was dissolved within the TiAl3 structure to form Ti(Al,Y)3. The established model revealed that ultrasonic vibration significantly promoted the formation of TiAl3, and that ultrasonic time was the main factor affecting its growth.

Exploring the effects of sand impacts and anodic dissolution on localized erosion-corrosion in sand entraining electrolyte

In this work, the initiation of the erosion-corrosion pits on the carbon steel in the flowing slurry is studied using electrochemical measurements in conjunction with surface morphology characterization. Results show that the intense sand impacts and the local anodic dissolution are the two basic requirements for the formation of erosion-corrosion pits. The appearance of erosion-corrosion pits could significantly enhance the synergy between erosion and corrosion. Through the three sets of tests using specially designed two-electrode system, it is found that the incubation sites of the erosion-corrosion pits are the original anodic sites rather than the local deformed areas at the conditions of low flow rate. The occurrence of erosion-corrosion pits is mainly induced by the sand impacts at the local anodic sites.

The dependence of drop evaporation rate and wettability on corrosion kinetics

The effect of corrosion of aluminum alloy on the droplets evaporation kinetics both for superhydrophilic and superhydrophobic surfaces is studied experimentally. The characteristic stages of the drop diameter changes due to corrosion correlate with the evaporation stages. Corrosion controls the drop wettability and the evaporation rate. At high rates of corrosion and with intense gas release, the evaporation rate is shown to decrease due to a reduction in the rate of heat supply to the droplet surface. The performed analysis of limiting factors illustrates that evaluating only electrochemical factors is not sufficient. Modeling the corrosion kinetics also requires taking into account the statistical nature of the corrosion process, which depends on the wettability and diameter of the drop. It has been for the first time demonstrated that the corrosion kinetics is determined by the modes of wetting. Expressions relating the corrosive current to the modes for the contact line of the drop are presented. Pre-temperature annealing of the material leads to an increase in the rate of corrosion and the appearance of large pits.

Ultrastructural Characteristics of DHA-Induced Pyroptosis

Microglial cells are resident macrophages of the central nervous system (CNS) that respond to bioactive lipids such as docosahexaenoic acid (DHA). Low micromolar concentrations of DHA typically promote anti-inflammatory functions of microglia, but higher concentrations result in a form of pro-inflammatory programmed cell death known as pyroptosis. This study used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to investigate the morphological characteristics of pyroptosis in BV-2 microglial cells following exposure to 200 µM DHA. Vehicle-treated cells are characterized by extended processes, spine-like projections or 0.4 to 5.2 µm in length, and numerous extracellular vesicles (EVs) tethered to the surface of the plasma membrane. In contrast to vehicle-treated cells, gross abnormalities are observed after treating cells with 200 µM DHA for 4 h. These include the appearance of numerous pits or pores of varying sizes across the cell surface, structural collapse and flattening of the cell shape. Moreover, EVs and spines were lost following DHA treatment, possibly due to release from the cell surface. The membrane pores appear after DHA treatment initially measured ~ 30 nm, consistent with the previously reported gasdermin D (GSDMD) pore complexes. Complete collapse of cytoplasmic organization and loss of nuclear envelope integrity were also observed in DHA-treated cells. These processes are morphologically distinct from the changes that occur during cisplatin-induced apoptosis, such as the appearance of apoptotic bodies and tightly packed organelles, and the maintenance of EVs and nuclear envelope integrity. Cumulatively, this study provides a systematic description of the ultrastructural characteristics of DHA-induced pyroptosis, including distinguishing features that differentiate this process from apoptosis.