Search Results (18)

This study aimed to examine the effects of crude garden cress seed oil (CGCSO) on frozen–thawed boar sperm qualities. Semen ejaculates (n = 12) were collected and further divided into six equal aliquots based on CGCSO concentrations (0, 0.5, 1, 1.5, 2, and 2.5% v/v) in the freezing extender. Semen samples were processed and cryopreserved utilizing the traditional liquid nitrogen vapor technique. Subsequently, semen samples were thawed in a thermos with warm water at 50 °C for 12 s and evaluated for sperm morphology using scanning electron microscopy, sperm motility using a CASA, sperm viability, acrosome integrity, mitochondrial function, MDA level, total antioxidant capacity (TAC), glutathione peroxidase (GSH-Px), and catalase (CAT) activity. The results indicated that 1% CGCSO resulted in superior post-thaw sperm characteristics, including enhanced sperm morphology, motility, viability, acrosome integrity, and mitochondrial function. Particularly, the total motile sperm increased by 16.5%, progressive motile sperm increased by 13.0%, viability improved by 15.1%, acrosome integrity increased by 14%, and mitochondrial function improved by 14.1% compared to the control group. CGCSO treatment at 1% and 1.5% exhibited the lowest level of MDA (45.73 ± 11.2 and 45.73 ± 11.3 µmol/L, respectively) compared to the other groups. The CGCSO-supplemented groups showed higher values of TAC, GSH-Px, and CAT than the control group but not significantly. Full article

Since 2010, huge quantities of Sargassum spp. algae have been proliferating in the Atlantic Ocean and stranding on Caribbean beaches, causing major economic, environmental, and health problems. In this study, an innovative high-density binderless particleboard was developed using uniaxial thermo-compression coupled with a cooling system. The raw material consisted of ground Sargassum seaweeds pre-treated by twin-screw extrusion with water to remove sea salt. The raw material and the particleboards were produced by using various analytical techniques such as Dynamic Vapor Sorption (DVS), Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), or Thermogravimetric Analysis (TGA). The experimental conditions for thermo-compression (temperature, pressure, time) were evaluated. The best thermo-compression conditions tested were 200 °C, 40 MPa pressure for 7.5 min. This resulted in a particleboard with high density (up to 1.63 ± 0.02 g/cm³) and high flexural strength/modulus (up to 32.3 ± 1.8 MPa/6.8 ± 0.2 GPa, respectively), but a low water contact angle of 38.9° ± 3.5°. Thermal analyses revealed the effect of alginates on the mechanical properties of particleboards. This work opens the door to a new way of adding value to Sargassum seaweed, using the whole algae with minimal pre-treatment. Full article

Chondroitin sulfate (ChS), chitosan (Chi), and fish gelatin (FG), which are byproducts of a fish-treatment small enterprise, were incorporated with glycerol (Gly) to obtain dense hydrogel membranes with reduced brittleness, candidates for dressing in wound healing applications. The mechanical properties of all samples were studied via Dynamic Mechanical Analysis (DMA) and tensile tests while their internal structure was characterized using Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Diffraction (XRD) instruments. Their surface morphology was analyzed by ThermoGravimetric Analysis (TGA) method, while their water permeability was estimated via Water Vapor Transmission Rate (WVTR) measurements. Wettability and degradation rate measurements were also carried out. Characterization results indicated that secondary interactions between the natural polymers and the plasticizer create the hydrogel membranes. The samples were amorphous due to the high concentration of plasticizer and the amorphous nature of the natural polymers. The integration of ChS led to decreased decomposition temperature in comparison with the glycerol-free sample, and all the materials had dense structures. Finally, the in vitro endothelial cell attachment studies indicate that the hydrogel membranes successfully support the attachment and survival of primary on the hydrogel membranes and could be appropriate for external application in wound healing applications as dressings. Full article

Bearings are usually used at high-speed and high-load conditions, so the bearing sleeve must be able to withstand large contact stress, which requires heat treatment. However, during the quenching process of the bearing sleeve, a vapor film is formed on the surface. Since the vapor film is not uniform along the axial direction during the process of boiling and breaking, it will cause uneven distortion of the bearing sleeve. This uneven distortion will cause the outer ring of the bearing to have elliptical distortion after heat treatment. However, the mechanism of this problem and how to reduce the elliptical distortion has not been completely solved. In this paper, two points on the inner wall and outer wall of the bearing sleeve in the orthogonal direction are measured by means of experiments, and the mechanism of the ellipticity distortion during the quenching process is revealed. Additionally, through its horizontal placement, oblique placement, and vertical placement, the cooling curve and cooling rate curve changes in the process of entering the quenching agent are studied; based on the cooling curve, the heat transfer coefficient of the bearing sleeve during quenching is obtained by the heat transfer equation. Input the heat transfer coefficient into the CAE heat treatment simulation software COSMAP, according to the Metallo-Thermo-Mechanics theory and the method of multi-field coupling, simulating the quenching process of GCr15 and 16MnCr5 materials. By comparison, the ellipticity value of the bearing placed at a 45° angle is smaller than that of the horizontally and vertically placed bearings, with the 16MnCr5 material having the smallest ellipticity value of 0.00016. The simulation results verified the distortion mechanism of the bearing sleeve during the quenching process and how to reduce the solution of elliptical distortion. Full article

Electricity–water cogeneration power plants are an important tool for advancing sustainable water treatment technologies because they provide a cost-effective and environmentally friendly solution for meeting the energy and water needs of communities. By integrating power and water production, these technologies can reduce carbon emissions and help mitigate the impact of climate change. This work deals with the energy and exergy analysis of a cogeneration plant for electrical power generation and water desalination using real operational data. The power side is a pressurized water reactor (PWR) nuclear power plant (NPP), while the desalination side is a multi-effect distillation (MED) system with a thermo-vapor compressor (TVC) plant coupled with a conventional multi-effect plant (ME-TVC-MED). A mathematical model was implemented in MATLAB software and validated through a comparison with previously published research. The exergy analysis was carried out based on the second law of thermodynamics to evaluate the irreversibility of the plant and the subsystems. In this study, the components of the sub-systems were analyzed separately to identify and quantify the component that has a high loss of energy and exergy. According to the energy and exergy analyses, the highest source of irreversibility occurs in the reactor core with 50% of the total exergy destruction. However, turbines, steam generators, and condensers also contribute to energy loss. Further, the thermodynamic efficiency of the cogeneration plant was obtained as 35.38%, which is more effective than other systems. In the ME-TVC-MED desalination unit, the main sources of energy losses are located in the evaporators and the thermo-compressor (about 50% and 36%, respectively). Moreover, the exergetic efficiency of the ME-TVC-MED unit was found to be low at 6.43%, indicating a high degree of technical inefficiency in the desalination process. Therefore, many opportunities exist to improve the performance of the cogeneration system. Full article

The influence of the method of applying the activating additive ammonium chloride and its concentration on the density and microstructure of zinc oxide ceramic obtained by cold sintering at 244 °C was investigated. The activating agent was applied by two methods: impregnation and subsequent autoclave treatment. When the powder was activated by the impregnation method, the crystal sizes remained at the initial level of 0.17–0.19 μm. After the autoclave treatment, the crystal sizes increased to 0.31–0.53 μm. Samples of cold sintering ZnO with relative density up to 0.96 and average grain sizes 0.29–0.86 μm were obtained. ZnO powders and ceramic samples were analyzed using SEM, TGA/DSC, and XRD to reveal the effect of the powder activation method and cold sintering conditions on the material microstructure. The effect of ammonium chloride concentration on grain growth and microstructure of ceramic samples is shown. It was found that the average grain size of ceramic samples with an increase in additive concentration passes through a minimum. In cold sintering of the autoclave activated powder, the effect of reducing the average grain size was observed. The results of this work are discussed on the basis of the idea of the solid-phase mobility of the crystal structure arising when interacting with an aqueous medium. Full article

Although the activating effect of an acetate medium in the cold sintering process of zinc oxide ceramics is well known, some problems need to be solved on the effect of process conditions and the initial powder’s preparation methods on the ceramic’s density and microstructure. This article describes an effect of the zinc acetate introduction method, its concentration in zinc oxide powder as well as that of the die sealing configuration on the density and microstructure of zinc oxide ceramics obtained by the cold sintering process at 244 °C. The activating additive of zinc acetate was applied in two ways: (1) impregnation in aqueous solution and (2) impregnation with subsequent treatment in water vapor. Zinc oxide powders and ceramics were analyzed using SEM, TGA/DSC/MS and XRD to reveal the effect of powder pre-treatment and sintering conditions on the material microstructure. Cold sintered ZnO ceramics samples with a relative density up to 0.99 and with average grain sizes from 0.28 to 1.71 μm were obtained. The die sealing by two Teflon sealing rings appeared to be the most effective. Full article

During the laser treatment of pigmented dermatosis such as Nevus of Ota, vapor bubbles will be generated by the laser with short pulse width and high energy density. Laser irradiation is efficacious for the clinical treatment of Ota’s Nevus caused by hyperplasia of melanosomes in dermis. Since the mechanism of the laser–melanosome interaction is not yet clear, the clearance rate is generally low and bleeding of irradiated skin frequently occurs. This work conducted a flow visualization experiment to investigate the laser–melanosome interaction mechanism by using high-speed imaging. Pigmented phantom was prepared to simulate the diseased dermis tissue, where agar acted as substrate and synthetic melanin particles was infused as hyperplastic melanosomes. Putting the phantom into water, its thermo-mechanical responses to single-pulse 1064-nm Nd:YAG laser irradiation with energy density of 4–7 J/cm² and pulse duration of 6 ns were recorded. The results indicated that laser-induced bubble formation caused by the gasification of tissue moisture is the key mechanism of laser–melanosome interaction, and an optimal energy density of 6 J/cm² is recommended. Full article

The great prospects for introducing the cold sintering process (CSP) into industry determine the importance of finding approaches to reduce the processing time and mechanical pressure required to obtain dense ceramics using CSP. The introducing zinc acetate into the initial ZnO powder of methods, such as impregnation, thermovapor autoclave treatment (TVT), and direct injection of an aqueous solution into a die followed by cold sintering process using a spark plasma sintering unit, was studied. The effect of the introduction methods on the density and grain size of sintered ceramics was analyzed using SEM, dynamic light scattering, IR spectroscopy, and XRD. The impregnation method provides sintered samples with high relative density (over 0.90) and significant grain growth when sintered at 250 °C with a high heating rate of 100 °C/min, under a uniaxial pressure of 80 MPa in a vacuum, and a short isothermic dwell time (5 min). The TVT and aqueous solution direct injection methods showed lower relative densities (0.87 and 0.76, respectively) of CSP ZnO samples. Finally, the development of ideas about the processes occurring in an aqueous medium with CSP and TVT, which are subject to mechanical pressure, is presented. Full article

In the present study, agro-food waste derived rice straw (RS) was valorized into cellulose microfibers (CMFs) using a green process of combined ultrasound and heating treatments and were thereafter used to improve the physical properties of thermoplastic starch films (TPS). Mechanical defibrillation of the fibers gave rise to CMFs with cumulative frequencies of length and diameters below 200 and 5–15 µm, respectively. The resultant CMFs were successfully incorporated at, 1, 3, and 5 wt% into TPS by melt mixing and also starch was subjected to dry heating (DH) modification to yield TPS modified by dry heating (TPSDH). The resultant materials were finally shaped into films by thermo-compression and characterized. It was observed that both DH modification and fiber incorporation at 3 and 5 wt% loadings interfered with the starch gelatinization, leading to non-gelatinized starch granules in the biopolymer matrix. Thermo-compressed films prepared with both types of starches and reinforced with 3 wt% CMFs were more rigid (percentage increases of ~215% for TPS and ~207% for the TPSDH), more resistant to break (~100% for TPS and ~60% for TPSDH), but also less extensible (~53% for TPS and ~78% for TPSDH). The incorporation of CMFs into the TPS matrix at the highest contents also promoted a decrease in water vapor (~15%) and oxygen permeabilities (~30%). Finally, all the TPS composite films showed low changes in terms of optical properties and equilibrium moisture, being less soluble in water than the TPSDH films. Full article

Analysis of scanning electron microscopy images was used to study the changes in the crystal size distribution of ZnO, which occurred during its processing in an aqueous medium at 220–255 °C and an equilibrium vapor pressure in an autoclave. The results were compared with those of ZnO placed in a die for treatment under similar conditions supplemented with mechanical pressure application in the cold sintering process. In both cases, ZnO was treated in the presence of an activating additive: either zinc acetate or ammonium chloride. During autoclaving, a powder consisting of fine ZnO monocrystals was obtained, while the cold sintering process led to ceramics formation. Under vapor pressure and mechanical pressure, the aqueous medium affected ZnO transformation by the same mechanism of solid-phase mobility activation due to the additives’ influence. The higher the content of additives in the medium, and the higher the mechanical pressure, the more pronounced activating effect was observed. Mass transfer during the cold sintering process occurred mainly by the coalescence of crystals, while without mechanical pressure, the predominance of surface spreading was revealed. In the initial ZnO powder, the average crystal size was 0.193 μm. It grew up to 0.316–0.386 μm in a fine-crystalline powder formed in the autoclave and to an average grain size of 0.244–0.799 μm in the ceramics, which relative density reached 0.82–0.96. A scheme explaining the influence of an aqueous medium on the solid-phase mobility of ZnO structure was proposed. It was found that the addition of 7.6 mol% ammonium chloride to the reaction medium causes the processes of compaction and grain growth similar to those observed in ZnO Cold Sintering Process with the addition of 0.925 mol% zinc acetate. Full article

Different approaches with different clinical outcomes have been found in treating capillary hemangioma (CH), venous lake (VL), or venous malformations (VM) of the lips. This retrospective study aims to assess scar quality, recurrence rate, and patient satisfaction after different surgeries with different laser wavelengths. A total of 143 patients with CH or VM were included. Nd:YAG laser was used for 47 patients, diode 980 nm laser was used for 32 patients (treatments by transmucosal photo-thermo-coagulation), Er,Cr:YSSG laser was used for 12 patients (treatments by excision), and CO₂ laser was used for 52 patients (treatments by photo-vaporization). The Manchester scar scale was used by practitioners to assess the scar quality. The recurrence rate and patients’ satisfaction were noted at different follow-ups during 12 months. Our retrospective study showed that laser-assisted aesthetic treatment of vascular lesions (CH, VL, and VM) of the lips can be considered effective regardless of the wavelength used (Er,Cr:YSGG, CO₂, Nd:YAG, and diode 980 nm) or the treatment procedure (transmucosal photo-thermo-coagulation, photo-vaporization, and surgical excision). There was no significant difference in patient and practitioner satisfaction with aesthetic outcome at 6 months follow-up. Furthermore, the treatments of lip vascular lesions performed using Er,Cr:YSGG and CO₂ lasers did not show any recurrence during the 12 months of follow-up, while recurrence rates of 11% ± 1.4% and 8% ± 0.9% were seen in the diode and Nd:YAG groups, respectively. Full article

Titanium and its alloys are characterized by high mechanical strength, good corrosion resistance, high biocompatibility and relatively low Young’s modulus. For many years, one of the most commonly used and described titanium alloys has been Ti-6Al-4V. The great interest in this two-phase titanium alloy is due to the broad possibilities of shaping its mechanical and physico-chemical properties using modern surface engineering techniques. The high coefficient of friction and tendency to galling are the most important drawbacks limiting the application of this material in many areas. In this regard, such methods as carburizing, nitriding, oxidation, and the synthesis of thin films using physical vapor deposition (PVD) and chemical vapor deposition (CVD) methods may significantly improve the tribological properties of titanium alloys. The influence of thermo-chemical treatment (oxidation, carburizing and nitriding) on tribological properties and corrosion resistance of Ti-6Al-4V alloy is presented in this paper. The results include metallographic studies, analysis of tribological and mechanical properties and corrosion resistance as well. They indicate significant improvements in mechanical properties manifested by a twofold increase in hardness and improved corrosion resistance for the oxidation process. The carburizing was most important for reducing the coefficient of friction and wear rate. The nitriding process had the least effect on the properties of Ti-6Al-4V alloy. Full article

The utilization of charcoal from woody biomass is an efficient way to reduce CO₂ emissions from the metallurgical industry. The main aim of this work is to study the charcoal production process from torrefied biomass. For this purpose, torrefaction (3 °C min⁻¹, 250 °C, 30 min) and carbonization (3 °C min⁻¹, 750 °C, 30 min) experiments of eucalyptus wood were carried out in a 3.5 L tank reactor. In the carbonization experiments, a thermo-catalytic treatment of the vaporized phase was also performed, with the objective of producing less condensates and H₂-rich gases. The results show that the torrefaction pre-treatment does not affect the chemical properties of charcoal but significantly improves the performance of the carbonization process, where more than 50 wt% of charcoal is obtained. In addition, the thermal and thermo-catalytic treatment of the vaporized phase during the carbonization of torrefied biomass yields better results than in the case of fresh biomass. When torrefied biomass is used as raw material and the reforming catalyst is employed to treat the vapors and gases, a proportion of 71 vol% of H₂ in the gases is achieved, together with very low quantities of condensates (8.0 wt%). This allows designing a carbonization process in which, in addition to charcoal, pure H₂ can also be produced. Full article

Recycling carbon fiber from residual carbon fiber reinforced plastics (CFRP) is one of the key aspects of the future in the field of waste management. This work presents the possibility of recovering chemical compounds through the thermo-catalytic treatment of the gases and vapors produced from the decomposition of the polymeric resin that takes place in the recycling of CFRP by pyrolysis. A lab-scale installation consisting of two reactors placed in series has been used for the experiments. In the first reactor, pyrolysis of poly(benzoxazine)-based composite waste has been carried out at 500 °C. In the second reactor, the thermo-catalytic treatment of gases and vapors has been performed at 900 °C in the presence of a commercial and a lab-prepared reforming catalyst. The thermal treatment of gases and vapors leads to a significant reduction in the collected liquids and a H₂-rich gas fraction. When reforming catalysts are used, the organic fraction of the liquids is virtually eliminated and gas fractions containing more than 50% H₂ in volume are generated. The results obtained show that it is possible to valorize the material content of the polymer resin, which represents an important advance in the recycling of CFRP by pyrolysis. Full article