Decrease In Thickness Research Articles

Creep failure mechanism of -oriented thin-wall Ni3Al-based single crystal superalloys

Currently, thin-wall structures are widely employed in aviation engine turbine blades to enhance cooling efficiency. However, the mechanical properties of thin-walled structures exhibit significant sensitivity to thickness. This study investigates the creep behavior of a <111>-oriented Ni3Al-based single-crystal superalloy with different thicknesses (0.3, 0.5, 0.8 mm) at 1100 °C/137 MPa. The results indicate a significant reduction in creep life with a decrease in wall thickness. The mechanism of various influencing factors on different creep stages was analyzed from both microscopic and macroscopic perspectives combined with finite element modeling. The alteration in stress state from thick-wall to thin-wall influences the number of slip systems that are activated, which mainly affects the primary and steady-state creep stages. Surface oxidation as time-dependent damage leads to non-invasive crack formation, somewhat increasing the steady-state creep strain rate of thin-wall samples. The accumulation and propagation in varying wall thicknesses of cleavage microcracks primarily influence the steady-state and tertiary creep stages, respectively, thereby exacerbating the thickness debit effect.

In vivo assessment of early effects of diamond-tipped microdermabrasion through the lens of line-field confocal optical coherence tomography.

Microdermabrasion is a cosmetic procedure that has gained popularity for skin rejuvenation by causing repetitive intraepidermal injury to stimulate the proliferation of fibroblasts and collagen production. Various clinical studies have demonstrated microdermabrasion's effectiveness in skin rejuvenation; however, most of these studies rely on clinical observation and scoring by observers rather than histologic or microscopic analysis. In our single-center prospective study, we used line-field confocal optical coherence tomography (LC-OCT), to non-invasively visualize the early effects of one microdermabrasion treatment on the facial epidermal and dermal structure. Using LC-OCT, this study aims to elucidate the microscopic and histological effects of microdermabrasion on epidermal and dermal structures, including epidermal thickness, as well as collagen and vascular patterns. Eight volunteers (Fitzpatrick skin types II-V) underwent one treatment of microdermabrasion. LC-OCT and VISIA imaging were performed before and 10 min after microdermabrasion, and at 48-h follow-up. Subjective evaluations of skin texture and adverse reactions were assessed 1 week posttreatment via a telephone call. Compared to LC-OCT images before treatment, images captured after one treatment of microdermabrasion showed a decrease in thickness and number of undulations in the stratum corneum. In the superficial dermis, enhancement in fibrillar collagen, as demonstrated by an increased prominence of crisscrossing hyper-refractile strands, was visualized. This was consistent with subjective and objective improvement in facial rhytids calculated by VISIA skin analysis. Treatment monitoring with LC-OCT demonstrated consistent histopathological changes with clinical visual improvement. Therefore, LC-OCT, has the potential to enable long-term histopathological monitoring of microdermabrasion and other cosmetic procedures without biopsy.

Electromagnetic and Thermal analysis of an Intra-layer no-insulation coil during Quench

The intra-layer no-insulation (LNI) layer-wound REBCO coil has been widely studied for its excellent high thermal stability in the research of nuclear magnetic resonance superconducting magnets. Due to the complex structure of the LNI layer-wound coil and the numerous factors that affect thermal stability, its quench characteristics are not clear. In this paper, a numerical multiphysics coupling model is established to study the transient electromagnetic and thermal behaviors of the LNI layer-wound coil during quench. The results indicate that temperature follows the diffusion law, while the currents evolve through electrical connection and electromagnetic induction. Due to the high contact resistance, the azimuthal current and axial current vary almost in units of the entire coil layer. The direction of the radial current upstream of the turn where a quench occurs is positive due to the bypassing behavior, while the radial current direction is negative downstream. The insulation material inside the LNI layer-wound coil strongly affects the quench propagation. When its thickness decreases, the equivalent radial thermal conductivity increases, thereby increasing the quench propagation velocity and current peak, and shortening the duration of the current response during quench.

Immediate implant placement in the anterior mandible: a cone beam computed tomography study

BackgroundThe placement of implants into the alveolar socket right after tooth extraction is called immediate implant placement (IIP). This approach has its particularities depending on which region of the jaws is involved. The anterior mandible region is peculiar due to the presence of mandibular incisors, which have the shortest roots among all permanent teeth.PurposeThis study aimed to investigate the factors that could be associated with the risk of either cortical bone wall perforation or invasion of the 2 mm secure distance from the surrounding anatomical structures (defined as unsafe implant placement), with IIP in the maxillary aesthetic zone, in a cone-beam computed tomography (CBCT) virtual study.Materials and methodsCBCT exams from 239 eligible subjects were investigated. Implants were virtually placed in two distinct positions: prosthetically-driven (along the long axis of the existing tooth) and bone-driven position (according to the available bone and with regard to nearby anatomical structures). Correlation between several variables was tested, and binary logistic regression analysis in order to assess of the possible associations between covariates and unsafe placement was performed.ResultsSafe placing implants was significantly higher for the bone-driven in comparison to the prosthetically-driven position (22.2% vs. 3.3%, respectively), and the 2-mm secure distance from anatomical structures was not possible to respect in the majority of cases (77.6% vs. 82.9%, respectively). Covariates associated with a higher risk of unsafe placement were tooth region (CI in relation to IL and CA), decrease of labial concavity angle (LCA), decrease of mandible basal bone height (MBBH), and decrease in mandibular bone thickness at the tooth apex level (MBT0).ConclusionThe possibility of safely placing immediate implants in the anterior mandible is significantly higher for bone-driven than in prosthetically driven position. Presurgical virtual planning with CBCT is a great tool for minimizing the risk of implant unsafe placement with regards to the anatomical conditions in the mandible.

Cortical morphology variations during the menstrual cycle in individuals with and without premenstrual dysphoric disorder

BackgroundPremenstrual dysphoric disorder (PMDD) is hypothesized to stem from maladaptive neural sensitivity to ovarian steroid hormone fluctuations. Recently, we found thinner cortices in individuals with PMDD, compared to healthy controls, during the symptomatic phase. Here, we aimed at investigating whether such differences illustrate state-like characteristics specific to the symptomatic phase, or trait-like features defining PMDD. MethodsPatients and controls were scanned using structural magnetic resonance imaging during the mid-follicular and late-luteal phase of the menstrual cycle. Group-by-phase interaction effects on cortical architecture metrics (cortical thickness, gyrification index, cortical complexity, and sulcal depth) were assessed using surface-based morphometry. ResultsIndependently of menstrual cycle phase, a main effect of diagnostic group on surface metrics was found, primarily illustrating thinner cortices (0.3 < Cohen's d > 1.1) and lower gyrification indices (0.4 < Cohen's d > 1.0) in patients compared to controls. Furthermore, menstrual cycle-specific effects were detected across all participants, depicting a decrease in cortical thickness (0.4 < Cohen's d > 1.7) and region-dependent changes in cortical folding metrics (0.4 < Cohen's d > 2.2) from the mid-follicular to the late luteal phase. LimitationsSmall effects (d = 0.3) require a larger sample size to be accurately characterized. ConclusionsThese findings provide initial evidence of trait-like cortical characteristics of the brain of individuals with premenstrual dysphoric disorder, together with indications of menstrual cycle-related variations in cortical architecture in patients and controls. Further investigations exploring whether these differences constitute stable vulnerability markers or develop over the years may help understand PMDD etiology.

Effects of Heat Transfer Characteristics of R32 and R1234yf with Al2O3 Nanoparticle through U-Bend Tube Evaporator

This study used the Ansys Fluent® computational fluid dynamics code in conjunction with a volume of fluid multiphase model and phase-change model to analyze the flow boiling evaporation heat transfer coefficient and flow patterns of R32 and R1234yf with Al2O3 nanoparticle through the U-bend tube with a curvature ratio for downward-oriented flow. The volume of fluid (VOF) model was used to follow the patterns at the interface, while the SST k-omega model was used to simulate the gas-liquid flow. This work has been validated by utilizing a R134a refrigerant. Simulations were performed at various mass fluxes, vapor qualities, and temperatures to determine the effects of these variables on heat transfer and frictional pressure decrease in the tube. R1234yf shows much better performance than the other pure refrigerants in terms of heat transfer and vaporization. The addition of nanoparticle Al2O3 with the refrigerants R32 and R1234yf significantly improved the heat transfer coefficient and increased the vapor fraction. The frictional pressure drop increases with increasing mass flux and decreases with increasing vapor quality due to a significant decrease in the liquid film thickness. The heat transfer coefficient, on the other hand, increases with increasing mass flux and decreases with vapor quality up to a point. There are certain changes in the heat transfer coefficient at the bend. After the bend, the frictional pressure drop increased at a higher rate than before the bend, and the vapor fraction increased at a higher rate.

Apparent color and Raman vibrational modes of the high-temperature superconductor Bi2Sr2CaCu2O 8+δ exfoliated flakes

Studying and controlling the properties of individual exfoliated materials is one of the first steps towards the fabrication of complex van der Waals systems. In this work, we present a systematic study of optical properties and micro-Raman spectroscopy on exfoliated flakes of the high-temperature superconductor Bi2Sr2CaCu2O 8+δ (BSCCO-2212). We demonstrate that these are quick and non-invasive techniques for studying air sensitive materials. The apparent color of BSCCO-2212 exfoliated flakes on SiO2/Si has allowed a rough and fast identification of the number of layers. By analyzing the optical contrast of different flakes we determined the complex refractive index in the visible range and found the optimal combination of illumination wavelength and substrate properties for the identification of flakes with different thickness. In addition, we report the hardening of the most characteristic Raman modes as flake thickness decreases, possibly caused by strain in the BiO and CuO2 planes. Moreover, the evolution of the Raman modes establishes a second approach to determine the thickness of BSCCO-2212 thin flakes. As BSCCO-2212 is a challenging material due to its sensitivity to ambient conditions, the present work provides a guide for the fabrication and characterization of complex van der Waals systems paving the way for studying heterostructures based on unconventional superconductors in the 2D limit.

Effects of quercetin on gentamicin-induced experimental testicular injury in rats.

The purpose of this study was to investigate the effects of gentamicin (GEN) on the testis and whether quercetin (QUE) has any protective effect. Twenty-four adult male Sprague-Dawley rats were divided into equal four groups: control (0.9% saline solution), GEN (80 mg∕kg GEN), QUE (50 mg∕kg QUE) and GEN+QUE (80 mg∕kg GEN + 50 mg∕kg QUE). Histopathological (HP) evaluation of testis was performed, epididymal sperm parameters were analyzed and oxidative status was evaluated. The use of QUE improved the HP findings, such as decrease in the germinal epithelial thickness in the testicular tissue of the GEN group, decrease in the Johnsen's tubular biopsy score (JTBS), increase in the rate of immature cell shedding tubules, and the apoptotic index (AI). In the GEN group, sperm count, and abnormal morphology increased compared to the control group; the viability and motility decreased according to the sperm analysis results. In the GEN+QUE group, QUE was found to improve sperm viability and morphology. In the GEN group, tissue malondialdehyde (MDA) levels increased while superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels decreased. Compared with the GEN+QUE group, it was found that the tissue MDA level decreased, while the levels of SOD, CAT and GPx increased. The results demonstrate that GEN impairs testicular structure and function, and QUE treatment can prevent this adverse effect.

The impact of treatment on endometrium ultrasound findings in reproductive age women with chronic endometritis

Purpose: to evaluate the dynamics of ultrasound parameter of structural changes of endometrium in B-mode before and after therapy in reproductive age women with chronic endometritis.Material and methods. A retrospective cohort study of 158 reproductive age patients (34.5 ± 6.5 years) with a established diagnosis of chronic endometritis was carried out. Ultrasound was performed twice prior and after comprehensive etiotropic therapy in the proliferative phase of the menstrual cycle with measurements of uterus volume, endometrium thickness and volume, with calculation of endometrial/uterine volume percentage ratio. Echogenicity and structure, including the presence of polyps, liquid in the uterine cavity, gas in the endometrial layer or on midline, the line of endometrial layers closure and the contour of endometrial midline were assessed.Results. There was no complete regress of any of pathological signs after treatment, but the frequency of most of them decreased significantly (p &lt; 0.05). At the same time, there was no significant changes in such signs as heterogeneous structure and increased echogenicity of the endometrium (p &gt; 0.05). In addition, a statistically significant decrease of endometrium thickness and volume, as well as endometrial/uterine volume ratio was obtained with a constant uterus volume (p &lt; 0.05).Conclusion. The dynamic decrease in the frequency of revealing of the ultrasound signs in chronic endometritis on the background of comprehensive etiotropic therapy allows to assess a positive therapeutic benefits.

Комбинированный метод лечения рефрактерного диабетического макулярного отека

Purpose. To determine the effectiveness of the anatomical and functional results of treatment of refractory diabetic macular edema after removal of the inner limiting membrane using the latest generation anti-VEGF drug. Material and methods. We examined 6 patients with 1st type and 2nd type diabetes mellitus. The average age of the subjects was 47.45 ± 27.15 years. Of these, there were 4 women and 2 men. 1st type diabetes mellitus was detected in 2 people, in other patients — 2nd type. 3 patients had previously undergone pan-retinal photocoagulation (from 1st to 2nd stages). All patients received intravitreal injections (anti-VEGF) of Eylea (4–5 injections) during the last year. According to the optical coherence tomogram (OCT), macular edema was recorded, recurring on average after 1.36 ± 0.85 months. All patients underwent surgical treatment. In the presence of lens opacity, surgical treatment was started with phacoemulsification of cataracts. A microinvasive subtotal vitrectomy was performed with the removal of the posterior layers of the vitreous body and proliferative membranes fixed to the retina. The removal of the inner boundary membrane was performed after its staining in the size of two to three diameters of the optic disc without any tamponade. After 2 months, two patients had an increase in retinal thickness in the fovea. These patients received one injection of Vabismo. Results. The compared groups did not differ in morphofunctional characteristics. In the postoperative period, there was a tendency to increase visual acuity and decrease retinal thickness, regression of hard exudates in 4 patients. In 2 patients, an increase in retinal thickness in the fovea was noted after 2 months. After intravitreal injection of the latest generation anti-VEGF drug (Vabismo), these patients also showed an increase in visual acuity, regression of solid exudates and a decrease in retinal thickness. Conclusion. Microinvasive subtotal vitrectomy with removal of the inner limiting membrane in combination with intravitreal injection of the latest generation anti-VEGF drug (Vabismo) is an effective method of treating refractory diabetic macular edema. Keywords: anti-VEGF, Vabismo, diabetic macular edema, intravitreal injections, optical coherence tomogram, subtotal vitrectomy, inner boundary membrane

Пилинг-ассоциированные тракции в хирургическом лечении диабетического макулярного отека

Vitreoretinal surgical treatment is indicated for diabetic macular edema (DME) in combination with vitreomacular interface abnormalities. Peeling of the retinal internal limiting membrane (ILM) is often used as part of the treatment. Tight adhesion of the posterior hyaloid membrane and the ILM may be the cause of the intraoperative retinal tractions development. Purpose. To assess the prevalence and impact of transient peeling-associated traction (tPAT) on the results and incidence of complications of surgical treatment of DME using ILM-peeling. Material and methods. As part of the study, a group of 40 patients was divided into 2 comparable subgroups according to the presence of tPAT (1st group — with tPAT, 2nd group — without tPAT). Patients in both groups received surgical treatment — three-port 27 Ga vitrectomy with ILM-peeling in a rounded area with a diameter of up to 2 DD centered on the fovea. ILM-peeling was performed using intraoperative tomographic control (optical coherence tomography). Results. In both groups, anatomical improvement was noted in the form of a decrease in foveal retinal thickness. At the same time, in 1st group there was no improvement in visual acuity, while in 2nd group its statistically significant increase was revealed. The presence of tPAT is associated with a higher incidence of postoperative neurodegenerative changes development of long-term follow-up period — disorganization of retinal inner layers and the formation of lamellar breaks in the fovea. According to correlation analysis, tPAT negatively affects the final value of visual acuity. Conclusion. It has been established that tPAT is a predictor of lower postoperative visual acuity, and is also a risk factor for retinal neurodegenerative changes in the long-term follow-up period. It is promising to evaluate the prevalence of tPAT in larger studies, reveal predictors of tPAT development and measures for their intraoperative prevention. Keywords: vitreoretinal surgery, ILM peeling, dosed fovea-sparing ILM peeling, optical coherence tomography, lamellar macular hole, disorganisation of retinal inner layers, peelingassociated tractions photocoagulation of the retina; long-term results

Methods to Increase Fatigue Life at Rib to Deck Connection in Orthotropic Steel Bridge Decks

Orthotropic steel bridge decks (OSDs) are very popular all over the world because of the low dead load, high stiffness in the longitudinal direction, high strength ratio to weight, and can be used in various types of bridges. The life of these bridges is affected by fatigue cracks in different portions. One of major areas where the fatigue cracks appear in these bridges is rib-to-deck connection. In this research finite element analysis is carried out by using ABAQUS/CAE 2022 software to determine the ways to increase the fatigue life at rib to deck connection in OSDs. In the first part, smaller models are simulated; stress concentration is analyzed and hot spot stress (HSS) is calculated according to International Institute of Welding (IIW) and Det Norske Veritas (DNV) recommendations. In the second part, a parametric analysis is carried out to analyze the effect of weld penetration, thickness of deck, thickness of rib and rib to deck connection type. In the third part, simulation of models similar to the real field is carried out to determine whether the double welded connections are better than single welded connections. Different models are analyzed for different load cases like single wheel load, double wheel load and also the position of the wheels is changed. The boundary conditions are changed to analyze whether the boundary condition has any significant effect on the result obtained. It is found that thicker decks, thinner ribs, and low penetrated welded connections reduce the stress concentrations at rib to deck connections which ultimately increase fatigue life. Among the parameters examined, deck thickness is the most important parameter. It is found that the percentage of stress increase with percentage decrease in deck thickness follows a power relation. The overall fatigue life of double welded connection is excepted to be lower since the stress concentration is maximum at the weld toe at deck on the outer side of the closed stiffener; however, if the cracks initiate on the inner side of closed stiffener, the cracks at the weld root of single welded connection can propagate much rapidly than the cracks initiating on the inner side of the closed stiffener at the weld toe, thereby reducing the fatigue life of the single-welded specimen significantly.

Ultrasonographic evaluation of diaphragm thickness and excursion: correlation with weaning success in trauma patients: prospective cohort study.

Prolonged mechanical ventilation (MV) subjects multiple trauma patients to ventilator-induced diaphragmatic dysfunction. There is limited evidence on the predictive role of diaphragm ultrasound (DUS) for weaning success in multiple trauma patients. Therefore, we evaluated Ultrasound of the diaphragm as a valuable indicator of weaning outcomes, in trauma patients. This prospective cohort study included 50 trauma patients from September 2018 to February 2019. DUS was performed twice: upon ICU admission and the first weaning attempt. The diagnostic accuracy of indexes was evaluated by ROC curves. The study included patients with a mean age of 35.4 ± 17.37, and 78% being male. The median injury severity score was 75 (42-75). The failure group exhibited significantly lower right diaphragmatic excursion (DE) compared to the success group (P = 0.006). In addition, the failure group experienced a significant decrease in both right and left DE from admission to the first attempt of weaning from MV (P < 0.001). Both groups showed a significant decrease in inspiratory and expiratory thickness on both sides during weaning from MV compared to the admission time (P < 0.001). The findings from the ROC analysis indicated that the Rapid shallow breathing index (RSBI) (Sensitivity = 91.67, Specificity = 100), respiratory rate (RR)/DE (Right: Sensitivity = 87.5, Specificity = 92.31), and RR/TF (Thickening Fraction) (Right: Sensitivity = 83.33, Specificity = 80.77) demonstrated high sensitivity and specificity in predicting weaning outcome. In the context of patients with multiple trauma, employing DUC and assessing diaphragmatic excursion, thickness, RR/DE index, RR/TF index, and RSBI can aid in determining successful ventilator weaning.

Investigation on microstructure and high-temperature wear properties of high-speed laser cladding Inconel 625 alloy

Inconel 625 alloy cladding layer was prepared by high-speed laser cladding (HLC) on Q245R steel substrate to improve the service performance of the structural components in the power industry in this work. A comprehensive study on the HLC Inconel 625 coating with different scanning speeds was conducted utilizing Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Laser Scanning Confocal Microscope (LSCM), X-Ray Diffraction (XRD), a microhardness tester, and an SRV-4 high-temperature friction and wear testing machine. The results show that the cladding layer's thickness and surface roughness decrease with the scanning speed increase. The cladding layers with different scanning speeds contain different microstructures. The phases mainly consist of γ-Ni and NbC. The microhardness of HLC coatings is generally higher than that of substrate, but decreased as the scanning speed increased. After the friction wear test at 500 °C, the cladding layer at the scanning speed of 2 m/min showed the best high-temperature wear resistance. The grain boundary area increases due to the formation of small-sized equiaxed dendrites, which resists dislocation slip and crack propagation, thereby enhancing high-temperature wear resistance. For the cladding layers at the higher scanning speed, the abrasive wear and the fatigue wear occur due to the precipitation of solid soluble elements such as Nb and Mo and the columnar crystal structures prone to deformation.

Large room temperature magnetoelectric response in quasi 1–2 nanocomposite films on mica substrate

AbstractA novel quasi 1–2 type magnetoelectric (ME) nanocomposite films composted of one‐dimensional CoFe2O4 nanofibers and two‐dimensional PbZr0.2Ti0.8O3 films on flexible mica substrate have been designed and fabricated. The ME coupling effects have been greatly enhanced due to the release of the clamping effect and the high strain transfer efficiency between the large aspect ratio of the nanofibers and ferroelectric thin films. The release of the clamping effect was confirmed by reducing the thickness of the mica substrate, in which the piezoelectric coefficient and ME coupling coefficient of the nanocomposite films have been greatly boosted by the decrease in the mica thickness. A large direct ME coupling coefficient of 630 mV/(cm Oe) and a converse ME coupling coefficient of 1.43 × 10−8 s/m have been achieved in the quasi 1–2 nanocomposite film with a substrate thickness of 25 µm. Furthermore, the stain‐mediated ME coupling was revealed by magnetic field/electric field‐induced local ferroelectric/magnetic domain switching dynamics.

Materials Science Analysis of RCCA Structural Materials and Calculations for Lifetime Extension

The paper considers the possibility of lifetime extending of the rod control cluster assemblies in operation by determining their residual lifetime using an approach that takes into account the actual position of the rod control cluster assembly in the core. Excessive conservatism was introduced by assuming that the immersion of the 10th working group in the core during all fuel campaigns is 70 %, while the actual position is 85-90 %. Taking into account the actual position of the rod control cluster assemblies indicates much less irradiation of the lower, most loaded part of control rod cladding and much less burnup of the 10B compared to 70 % immersion of the rod control cluster assemblies, since they are in the area of lower neutron flux density.&#x0D; The results of a comprehensive analysis of available studies and test results to determine the phenomena that can potentially approach the achievement of the boundary state of the structural components or limit the lifetime of control rods and rod control cluster assemblies in general are presented. Such phenomena include general corrosion of structural materials (42CrNiMo, Cr18Ni10Ti) (decrease in wall thickness, increased transfer of radioactive corrosion products the coolant); radiation resistance (degradation of mechanical characteristics) of control rod cladding materials (42CrNiMo) and other structural components of the rod control cluster assemblies (42CrNiMo, CrKh18Ni10Ti); radiation resistance of neutron-absorbing materials (B4C, Dy2O3∙TiO2); compatibility of absorbing materials with the control rod cladding.&#x0D; Based on the results of post-irradiation examinations of control rods tested in research reactors as dummy rods or rod control cluster assembly rods operated in the VVER-1000 core, the following boundary values were established that can be used as criteria for maintaining the integrity of the control rod cladding: maximum fast neutron fluence in the lower, most loaded part of the control rod cladding (in the weld area of the lower end plug and the cladding) should not exceed 34×1021 n/cm2; maximum burnup of the 10B isotope should not exceed 45 %. If these two criteria are met, the possibility of other potentially damaging phenomena is too low.&#x0D; According to the calculations that use the schedule of changes in the position of the rod control cluster assemblies of the control group and the power of one of the power units during one fuel cycle, one can preliminary conclude that the proposed approach will extend the lifetime of almost all rod control cluster assemblies from 25500 to 38000 hours in the automatic control group and from 75600 to 113500 hours in the shutdown group. The residual lifetime should be assessed for a particular power unit and each rod control cluster assembly separately, since each rod control cluster assembly has its own operating history.

Modeling and analysis of 3D mixed lubrication in marine cam–tappet pair

During the operation of the marine cam–tappet pair, affected by periodic dynamic load, transient velocity, and micromorphology, it usually operates in a mixed lubrication state. Under extreme operational conditions, contact is likely to occur at the asperity of the interface, leading to problems such as stress concentration and dry contact. Considering the transient dynamics and three-dimensional roughness of cam–tappet pair, a mixed-elastohydrodynamic lubrication model is developed in this article, while the effects of surface waviness on the lubrication state are also investigated. The results show that the film thickness can be increased by 0.098 μm, and the coefficient of friction can be reduced by 10.6% when the wavelength ratio ranges from 1/6 to 6. However, when the amplitude exceeds 0.6 μm, the coefficient of friction may reach 0.10. Under conditions of low speed and high load, the film thickness decreases and contact load ratio increases. And about 30% reduction in film thickness is achieved on cam–tappet pair, potentially leading to increased wear or scuffing failure.

Effect of annealing in air on the properties of carbon-rich amorphous silicon carbide films

Thermal stability of thin carbon-rich Si carbide films was studied. Air anneals at the temperatures up to 700 °C were used to model the operation thermal conditions of the films in photoelectronic devices such as solar cells covered by Si carbide antireflection coatings. Si carbide films with different carbon-to-silicon ratios were studied. Annealing in air was shown to lead to consecutive film oxidation and transformation from Si carbides to oxidized Si carbide composites. The oxidized composites demonstrated the changes in thickness, element composition and optical properties as compared to the non-annealed films. At this, the films with higher Si content showed better stability of the optical properties at increased temperatures. During annealing, the increase of the film thickness by Si oxide formation competed with the thickness decrease by formation and evaporation of carbon oxide.

MAPLE deposition of hybrid PLGA-Fe3O4- Cypress-PEDOT: PSS coatings

We report on the Matrix Assisted Pulsed Laser Evaporation, laser technology for depositing biocompatible, antimicrobial, hydrophilic, and biodegradable complex hybrid polymeric system loaded with essential cypress-oil and magnetite nanoparticles as resorbable implants, capable of targeting possible hyperthermia applications, an anticancer moderate field heating therapy. Magnetite nanoparticles based on iron oxide (Fe3O4) coated with Cypress essential oil (denoted: Fe3O4- Cypress) and embedded in PLGA (poly(lactic-co-glycolic acid) (denoted: PLGA-Fe3O4- Cypress-) and PLGA - poly(3,4-ethylene dioxythiophene) doped with poly(styrene sulfonate) anions) (PEDOT: PSS) mixture (denoted: PLGA-Fe3O4- Cypress- PEDOT: PSS) were used as MAPLE targets. The controlled drug delivery of the active Cypress oil, an antimicrobial therapeutic agent from Fe3O4- Cypress nanoparticles could be possible by applying an external radio frequency (RF) magnetic field. The Fe3O4-Cypress-based powders as well as the final hybrid coatings have been characterized in terms of stoichiometry, morphology, magnetic, antimicrobial properties, biocompatibility, and response to external physical stimuli. FTIR analyses confirmed the quasi-stoichiometric laser transfer of organic compounds while the XRD evidenced the semicrystalline structure of deposited thin films. SEM and AFM images evidence that conductive polymer addition led to the films' relief flattening and a decrease in the coatings' thickness and roughness by changing the polymeric packaging. The samples containing conductive polymer exhibited 3 times higher current and corrosion rate values. All coatings are hydrophilic and revealed enhanced cellular viability when cultured with osteoblast-like MG-63 cells. The composite structures exhibited significant antimicrobial activity against Gram-positive (Staphylococcus aureus), and Gram-negative (Escherichia coli) bacteria, as well as to the opportunistic yeast Candida albicans.

СЕЗОННЫЕ И МЕЖГОДОВЫЕ ИЗМЕНЕНИЯ ВОЗРАСТНОЙ СТРУКТУРЫ ЛЕДЯНОГО ПОКРОВА ГРЕНЛАНДСКОГО МОРЯ В ЗИМНИЙ ПЕРИОД

Seasonal and interannual changes in the Greenland Sea ice age composition during winter months for seven standard age categories are analyzed. To estimate the amount of the ice of different age categories, the digital archive of the region’s ice charts for the period 1997-2022 produced by the Arctic and Antarctic Research Institute is used. Statistical insignificance of linear trends has been revealed for the main age categories of the Greenland Sea ice. A comparison of the obtained estimates of the variability in the amount of the ice of different age categories and earlier studies shows that the quantitative changes in the Greenland Sea ice age composition started before 1997. The data on the ice age composition over a 25-year observation period alone are insufficient to draw an unambiguous conclusion about a decrease in the Greenland Sea ice thickness.