Search Results (60)

The presented study illustrates the use of photoelasticity as an effective tool for validating the results of finite element method (FEM) simulations of auxetic structures. This research focuses on comparing stress distributions in planar auxetic models under symmetrical and asymmetrical loading conditions. Experimental measurements, conducted using an optically sensitive material (PSM-1), were found to align closely with FEM predictions, with deviations within 5%. This agreement highlights the accuracy of both methods, though discrepancies were noted in areas with lower stress levels due to fringe order reading precision. The experimental process makes it possible to take into account real conditions and inaccuracies in production, while numerical modelling is based on ideal conditions. The findings affirm the value of photoelasticity for stress field analysis in complex geometries, particularly for auxetic structures, and underscore its role in verifying and refining computational models. The study concludes that photoelasticity can be a valuable tool for designers and engineers in verifying FEM simulations, even without the use of digital processing and the evaluation of measured data. Full article

Rapid prototyping has a wide range of applications across various fields, both in industry and for private use. It enables the production of individual parts in a short time, independent of supply chains, which is particularly important in remote locations. Among all 3D printing technologies, stereolithography using photo resins is the most accessible and offers the highest printing quality. However, the strength properties of parts made from photo resins remain a critical concern. In this study, we conducted experimental research to investigate the effect of load vector orientation under uniaxial compression on the elastic and mechanical properties of 3D-printed cylindrical samples. The results revealed that samples with layers oriented at 60° to the load vector exhibited the highest strength, while those with layers at 30° to the load vector showed the lowest strength. Samples with layers aligned parallel or perpendicular to the load vector demonstrated similar strength properties. Under quasi-elastic loading, samples with layers parallel to the load vector exhibited the highest Young’s modulus and the lowest Poisson’s ratio. Conversely, samples with layers oriented at 30° to the load vector displayed the highest Poisson’s ratio. Microstructural analysis revealed that the anisotropy in the mechanical properties of the 3D-printed samples is attributed to the layered, heterogeneous structure of the photoresin, which exhibits varying degrees of polymerization along the printing axes. The upper part of each layer, with a lower degree of polymerization, contributes to the ductile behavior of the samples under shear stresses. In contrast, the lower part of the layer, with a higher degree of polymerization, leads to brittle behavior in the samples. Full article

The European Society for Laser Dermatology (ELSD) has established recommendations for safe and effective photo epilation; however, short-term common adverse effects occur as a result of laser treatment, such as edema and perifollicular erythema. Post-inflammatory hyperpigmentation also appears in certain skin types. Very few clinical studies have been conducted on the topical application of cosmetic skin care products aimed at decreasing the adverse effects on the skin epidermis following laser-assisted epilation procedures. Stem cells are found in plant and animal organisms and are responsible for the growth and restoration of damaged tissues. Plant stem cells divide throughout the life of the plant, creating new plant parts. Our aim was to develop a new cosmetic cream to decrease the intensity of some of the side effects of laser epilation and thus reduce the administration of topical medication. We developed a formulation with the active substance Olea europaea (Olive) Callus Culture Lysate (OLEA VITAE™ 02), which is derived from plant stem cells of the Mediterranean wild variety of Olea europaea, for application following laser epilation with an Nd:YAG 1064 nm laser. The new skin care cream was tested for its physicochemical and microbiological stability, according to the European Pharmacopoeia. The impacts of this substance on the potential side effects of Nd:YAG 1064 nm application, i.e., trans-epidermal water loss, keratin hydration, melanin, erythema, and skin elasticity, in comparison with the appropriate placebo, were investigated using biophysical measurements and a self-assessment questionnaire. Skin biopsies were also performed to evaluate the influence of the procedure and the application of the products on the epidermis and papillary dermis thickness. According to our findings, the incorporation of the plant stem cell extract of Olea europaea into our cream resulted in a stable cream with an appealing texture. Furthermore, the activity of erythema and hyperpigmentation was decreased when the cream was applied after Nd:YAG 1064 nm laser epilation. Full article

Introduction: Gold threads became widely used in esthetic surgery in the early 1990s. Produced in Spain, these threads consisted of a gold thread (5/0) with a diameter of 0.1 mm, composed of 99.99% pure gold, which was combined with a polyglycolic thread. Since then, discussions about their effectiveness have continued, which is the focus of our study. Patients and Methods: Gold thread implantation was performed on 11,062 patients in four clinics in Moscow over the course of 28 years. This study used a comparative analysis of photo collages created for the visual representation of data and changes before and after the procedure, as well as patient satisfaction assessments using the Patient Satisfaction Scale (PSS). We examined the results of 492 patients who underwent gold thread implantation in the face between 1996 and 2024. Of these patients, 86% were women aged 30 to 60 years, 11% were women aged 20 to 30 years, and 3% were men aged 25 to 60 years. Results: One year after thread implantation, the PSS assessment showed a 91% success rate with minimal complications. Patient satisfaction was high, with an average score of 4.8 out of 5 after one month, 4.7 after six months, and 4.6 after one-year post-procedure. Discussion: Gold thread implantation is a minimally invasive procedure that has demonstrated a high level of safety, making it an effective option for facial rejuvenation. Histological studies have shown that gold threads stimulate the production of collagen and elastin and activate angiogenesis, thereby improving skin nourishment and hydration, as well as enhancing the skin tone, elasticity, and turgor. To improve the qualitative characteristics of the skin, it is necessary to work in the subcutaneous layer. Conclusions: Gold thread implantation strengthens the connective tissue framework at the implantation site, thus improving skin nourishment and hydration. Gold threads provide a long-term rejuvenating effect, slowing the ptosis of the soft tissue of the face and neck. Gold thread implantation does not interfere with tissue dissection during surgical interventions or the performance of any cosmetic procedures, including hardware-based treatments. Full article

Metabolites resulting from the bacterial fermentation of dietary fibers, such as short-chain fatty acids, especially butyrate, play important roles in maintaining gut health and regulating various biological effects in the skin. However, butyrate is underutilized due to its unpleasant odor. To circumvent this organoleptic unfavorable property, phenylalanine butyramide (PBA), a butyrate precursor, has been synthesized and is currently available on the market. We evaluated the inhibition of mushroom tyrosinase by butyrate and PBA through in vitro assays, finding IC₅₀ values of 34.7 mM and 120.3 mM, respectively. Docking calculations using a homology model of human tyrosinase identified a putative binding mode of PBA into the catalytic site. The anti-aging and anti-spot efficacy of topical PBA was evaluated in a randomized, double-blind, parallel-arm, placebo-controlled clinical trial involving 43 women affected by photo-damage. The results of this study showed that PBA significantly improved skin conditions compared to the placebo and was well tolerated. Specifically, PBA demonstrated strong skin depigmenting activity on both UV and brown spots (UV: −12.7% and −9.9%, Bs: −20.8% and −17.7% after 15 and 30 days, respectively, p < 0.001). Moreover, PBA brightened and lightened the skin (ITA°: +12% and 13% after 15 and 30 days, respectively, p < 0.001). Finally, PBA significantly improved skin elasticity (Ua/Uf: +12.4% and +32.3% after 15 and 30 days, respectively, p < 0.001) and firmness (Uf: −3.2% and −14.9% after 15 and 30 days, respectively, p < 0.01). Full article

Plasmin is a serine protease induced by UV-irradiation in skin that contributes to inflammation. We showed that plasmin is upregulated in photo-exposed facial skin and that this correlates with increased transepidermal water loss (TEWL). Plasmin activity upregulates downstream pathways such as pro-inflammatory cytokines and matrix-metalloproteinases (MMPs). In addition, the plasminogen system modulates cutaneous melanogenesis. In this study, we investigated potential skin-aging effects of plasmin with a dual inhibitor of plasmin and its activator urokinase (uPA). We established a range of in vitro and ex vivo assays to investigate inflammation, MMP-9 activation, and collagen modulation, and the melanogenesis modulation activity of plasmin. A specific plasmin inhibitor, Amidinobenzyl Benzylsulfonyl D-Seryl Homophenylalaninamide Acetate (ABSHA), was used in these assays to downregulate these effects. We found that ABSHA was able to down-regulate UV-irradiation-induced MMP-9 expression, and subsequent collagen IV degradation, ex vivo. In addition, the increased melanin synthesis in epidermal melanocytes was reduced significantly by ABSHA. Furthermore, dermal fibroblasts treated with the plasmin inhibitor showed increased collagen I synthesis. We further investigated these effects in a two-month, monocentric, placebo-controlled human study on female Chinese volunteers. We found a significant increase in collagen density by ultrasound measurement and an increase in elasticity by cutometer assessment in the group using a formulation consisting of a 10 ppm ABSHA solution. This resulted in decreased wrinkle volumes on both the forehead and crow’s feet as shown by Primos CR. Looking at age spots, there was a decrease in overall ITA° and melanin density as well as in the total age spot area. Our results establish plasmin as a skin-aging enzyme. Using specific inhibitors against plasmin shows promise against age-induced skin conditions. Full article

This article primarily focuses on the study of image-based localization technology. While traditional methods have made significant advancements in technology and applications, the emerging field of visual image-based localization technology demonstrates tremendous potential for research. Deep learning has exhibited a strong performance in image processing, particularly in developing visual navigation and localization techniques using large-scale visual models. This paper introduces a sophisticated scene image localization technique based on large models in a vast spatial sample environment. The study involved training convolutional neural networks using millions of geographically labeled images, extracting image position information using large model algorithms, and collecting sample data under various conditions in elastic scene space. Through visual computation, the shooting position of photos was inferred to obtain the approximate position information of users. This method utilizes geographic location information to classify images and combines it with landmarks, natural features, and architectural styles to determine their locations. The experimental results show variations in positioning accuracy among different models, with the most optimal model obtained through training on a large-scale dataset. They also indicate that the positioning error in urban street-based images is relatively small, whereas the positioning effect in outdoor and local scenes, especially in large-scale spatial environments, is limited. This suggests that the location information of users can be effectively determined through the utilization of geographic data, to classify images and incorporate landmarks, natural features, and architectural styles. The study’s experimentation indicates the variation in positioning accuracy among different models, highlighting the significance of training on a large-scale dataset for optimal results. Furthermore, it highlights the contrasting impact on urban street-based images versus outdoor and local scenes in large-scale spatial environments. Full article

This study explores the previously uncharted territory of the effects of ultraviolet (UV) radiation on diabetic skin, compared to its well-documented impact on normal skin, particularly focusing on carcinogenesis and aging. Employing hairless SKH-hr2, Type 1 and 2 diabetic, and nondiabetic male mice, the research subjected these to UV radiation thrice weekly for eight months. The investigation included comprehensive assessments of photoaging and photocarcinogenesis in diabetic versus normal skin, measuring factors such as hydration, trans-epidermal water loss, elasticity, skin thickness, melanin, sebum content, stratum corneum exfoliation and body weight, alongside photo documentation. Additionally, oxidative stress and the presence of hydrophilic antioxidants (uric acid and glutathione) in the stratum corneum were evaluated. Histopathological examination post-sacrifice provided insights into the morphological changes. Findings reveal that under UV exposure, Type 1 diabetic skin showed heightened dehydration, thinning, and signs of accelerated aging. Remarkably, Type 1 diabetic mice did not develop squamous cell carcinoma or pigmented nevi, contrary to normal and Type 2 diabetic skin. This unexpected resistance to UV-induced skin cancers in Type 1 diabetic skin prompts a crucial need for further research to uncover the underlying mechanisms providing this resistance. Full article

Secondary aluminum dross containing a large amount of active substance can be used to prepare concrete. The mechanical strengths, the mass loss rate (MR) and the relative dynamic modulus of elasticity (RME) of ultra-high-performance concrete with secondary aluminum dross are researched. The NaCl freeze–thaw cycles (F-Cs) and dry–wet alternation (D-A) effects with NaCl and Na₂SO₄ are considered. The corresponding permeability of chloride ions and the carbonation depth (D_c) are obtained. The scanning electron microscope (SEM) photos are researched to reveal the variation of the mechanical mechanism. Results show that after specimens’ suffering from the action of 20 NaCl D-As, the MR of ultra-high-performance concrete is the highest. Specimens exposed to 200 NaCl F-Cs show the lowest MR and CMC. The RME of UHPC under salt actions increase in the order of 20 NaCl D-As < 20 Na₂SO₄ D-As < 200 NaCl F-Cs. After suffering 200 NaCl F-Cs, 20 Na₂SO₄ D-As and 20 NaCl D-As, the corresponding D_c values are 1.86 mm to 2.31 mm, 1.79 mm to 2.23 mm and 2.11 mm to 2.76 mm. The flexural strength decreases at the rates of 0.99%–25%, 3.92%–27.84% and 1.47%–21.59% respectively. The MR increases and the RME decreases as the cubic function changes with the amount of salt erosion. After the secondary aluminum dross is added, the CMC decreases at the rates of 0% to 11.53%, 0% to 33.17% and 0% to 8.41% during the process of the salt action. The SAD can reduce the D_c with the decreasing rates of 19.48%, 23.55% and 19.73%. The SAD can increase the compactness of ultra-high-performance concrete. Ultra-high-performance concrete suffering from 20 NaCl D-As shows the largest number and the highest width of cracks. However, when the specimens are exposed to 20 Na₂SO₄ D-As, the number of cracks is the lowest and the width is the narrowest. Full article

7-MEGA^TM is a food product made from purified Alaska pollack fish oil containing palmitoleic acid (16:1), commonly referred to as omega-7. We sought to quantitatively evaluate whether this substance inhibits skin aging. A total of 101 middle-aged females were randomly allocated to the intervention (N = 50) or placebo group (N = 51). Each participant was advised to take either 500 mg of 7-MEGA^TM or a placebo twice daily for 12 weeks. The primary outcomes were the degree of improvement in wrinkles and the degree of moisture filling after consumption for 12 weeks compared to baseline. The secondary outcomes were improvement in skin wrinkles; moisture changes at 4 and 8 weeks from baseline; changes in transdermal water loss, skin elasticity, the melanin index, the erythema index, and the Global Photo Damage Score. We found a significant improvement in skin wrinkles and elasticity at 12 weeks in the 7-MEGA^TM-consuming group compared to that in the placebo group; skin moisture, elasticity, and the melanin index were also improved. No supplement-related adverse reactions were observed and 7-MEGA^TM was identified as safe. 7-MEGA^TM was effective for human skin function in terms of wrinkles, moisture, elasticity, and melanin production and may be useful as a skin nutritional supplement. Full article

A relevant problem in the development and improvement of numeric analytical methods for the research of structures, buildings and construction is studying the stress–strain state of structures and construction with boundaries that have complex shapes. Deformations and stresses arise in a domain with a geometrically non-linear shape of the boundary (cut-outs and cuts). These stresses and deformations have great values and gradients. Experiments carried out using the photoelasticity method show a change in the deformation order ratios for different subareas of the boundary cut-out area depending on proximity to the apex of the angular cut-out. Areas with minor deformations are observed, and areas where linear deformations and shears are more significant than rotations are also observed. In addition, areas where section rotations are more significant than linear and shear deformations are observed. According to the experimental data, the mathematical model of the SSS in the area of the apex of the cut-out of the domain boundary should take into account non-linear deformations. Hence, it is necessary to formulate the boundary value problem of the theory of elasticity, taking into account the geometrical non-linearity. The research aim of this paper is to formulate the problem of the elasticity theory taking into account the geometrical non-linearity in furtherance of the proposed mathematical model justified by the experimental data obtained using the photoelasticity method. The obtained formulation of the elasticity theory problem allows analyzing the form of the system of equations of the boundary value problem depending on the proximity of the considered area to the irregular point of the boundary, i.e., taking into account the difference in the effect of linear and shear deformations, rotations and forced deformations on the solution to the geometrically non-linear elastic problem dealing with forced deformations in the area of an angular cut-out of the boundary of the plane domain. Full article

In order to meet the requirements of dynamic monitoring from a bird’s eye view for typical rapidly changing processes such as mechanical rotation and photoresist exposure reaction, we propose a vertical high-speed Mueller matrix ellipsometer that consists of a polarization state generator (PSG) based on the time-domain polarization modulation and a polarization state analyzer (PSA) based on division-of-amplitude polarization demodulation. The PSG is realized using two cascaded photoelastic modulators, while the PSA is realized using a six-channel Stokes polarimeter. On this basis, the polarization effect introduced by switching the optical-path layout of the instrument from the horizontal transmission to the vertical transmission is fully considered, which is caused by changing the incidence plane. An in situ calibration method based on the correct definition of the polarization modulation and demodulation reference plane has been proposed, enabling the precise calibration of the instrument by combining it with a time-domain light intensity fitting algorithm. The measurement experiments of SiO₂ films and an air medium prove the accuracy and feasibility of the proposed calibration method. After the precise calibration, the instrument can exhibit excellent measurement performance in the range of incident angles from 45° to 90°, in which the measurement time resolution is maintained at the order of 10 μs, the measurement accuracy of Mueller matrix elements is better than 0.007, and the measurement precision is better than 0.005. Full article

The degree of quality of thermoplastic injection-molded parts can be established based on their weight, appearance, and defects. However, the conditions of the injection process may induce effects on the mechanical performance of the injected parts, and the residual stresses can cause cracks or early failures when an external load or force is applied. To evaluate these mechanical behaviors, different experimental techniques have been reported in the literature, where digital photoelasticity has stood out both for being a non-contact technique and for achieving quantitative results through sophisticated computational algorithms. Against this background, our proposal consists of analyzing the overall residual stress distribution of parts injected under different molding conditions by using digital photoelasticity. In this case, the specimens are subjected to bending strength tests to identify possible effects of the injection process conditions. The findings show that, at mold temperatures of 80 °C, flow-induced residual stresses increase with packing pressure. However, these internal stress levels do not affect the external load applied by the mechanical bending test, while the mass injected at higher levels of packing pressure helps to increase the bending strength of the injected part. At lower mold temperatures (50 °C), the mechanical strength of the injected part is slightly reduced, possibly due to a lower effect of the packing pressure. Full article

In order to study the effect of TiB₂ particles on the mechanical properties of TiB₂/6061Al composites, a series of 3D TiB₂/6061Al representative volume elements (RVEs) were established based on SEM photos. This model took into account the ductile damage of the matrix and the traction separation behavior of the interface, and the linear damage evolution law was introduced to characterize stiffness degradation in the matrix elements. Mixed boundary conditions were used in the RVE tensile experiments, and the accuracy of the predicted result was verified by the agreement of the experimental stress-strain curve. The results showed that the addition of TiB₂ particles can effectively promote the load-bearing capacity of the composite, but elongation is reduced. When the weight fraction of TiB₂ increased from 2.5% to 12.5%, the elastic modulus, yield strength, and tensile strength increased by 8%, 10.37%, and 11.55%, respectively, while the elongation decreased by 10%. The clustering rate of the TiB₂ particles is also an important factor affecting the toughness of the composites. With an increase in the clustering rate of TiB₂ particles from 20% to 80%, the load-bearing capacity of the composites did not improve, and the elongation of the composites was reduced by 8%. Moreover, the high-strain region provides a path for rapid crack propagation, and particle spacing is a crucial factor that affects the stress field. Full article

Biopolymer hydrogels have become an important group of biomaterials in experimental and clinical use. However, unlike metallic or mineral materials, they are quite sensitive to sterilization. The aim of this study was to compare the effects of gamma irradiation and supercritical carbon dioxide (scCO₂) treatment on the physicochemical properties of different hyaluronan (HA)- and/or gelatin (GEL)-based hydrogels and the cellular response of human bone marrow-derived mesenchymal stem cells (hBMSC). Hydrogels were photo-polymerized from methacrylated HA, methacrylated GEL, or a mixture of GEL/HA. The composition and sterilization methods altered the dissolution behavior of the biopolymeric hydrogels. There were no significant differences in methacrylated GEL release but increased methacrylated HA degradation of gamma-irradiated samples. Pore size/form remained unchanged, while gamma irradiation decreased the elastic modulus from about 29 kPa to 19 kPa compared to aseptic samples. HBMSC proliferated and increased alkaline phosphatase activity (ALP) particularly in aseptic and gamma-irradiated methacrylated GEL/HA hydrogels alike, while scCO₂ treatment had a negative effect on both proliferation and osteogenic differentiation. Thus, gamma-irradiated methacrylated GEL/HA hydrogels are a promising base for multi-component bone substitute materials. Full article