Search Results (12,936)

Eye disorders affect a substantial portion of the global population, yet the availability of efficacious ophthalmic drug products remains limited. This can be partly ascribed to a number of factors: (1) inadequate understanding of physiological barriers, treatment strategies, drug and polymer properties, and delivery systems; (2) challenges in effectively delivering drugs to the anterior and posterior segments of the eye due to anatomical and physiological constraints; and (3) manufacturing and regulatory hurdles in ocular drug product development. The present review discusses innovative ocular delivery and treatments, encompassing implants, liposomes, nanoparticles, nanomicelles, microparticles, iontophoresis, in situ gels, contact lenses, microneedles, hydrogels, bispecific antibodies, and gene delivery strategies. Furthermore, this review also introduces advanced manufacturing technologies such as 3D printing and hot-melt extrusion (HME), aimed at improving bioavailability, reducing therapeutic dosages and side effects, facilitating the design of personalized ophthalmic dosage forms, as well as enhancing patient compliance. This comprehensive review lastly offers insights into digital healthcare, market trends, and industry and regulatory perspectives pertaining to ocular product development. Full article

New environmentally friendly methods for extracting vegetable oils are in development, with a focus on pressurized liquid extraction (PLE) in an intermittent process. Ethanol, a renewable and generally recognized as safe (GRAS) solvent, is gaining prominence in this process. It is crucial for these methods to maintain the physicochemical characteristics of the extracted oils and be economically viable on a large scale. Using SuperPro Design software v 8.5, a simulation of PLE scaled up to industrial levels was conducted. Measurements of oils extracted with pressurized hexane and ethanol showed minimal density variations, with slightly higher viscosity for ethanol-extracted oil. Accelerated oxidative degradation revealed a longer induction period for hexane-extracted oil, indicating that ethanol-extracted oil degrades more easily. The antioxidant activity of the oil extracted with hexane was lower than that with ethanol. In the differential scanning calorimetry analysis, the oils extracted with hexane and ethanol presented onset melting point temperatures of −43.2 and −36.1 °C, respectively. The economic assessment considered 16 scenarios, showing a return on investment ranging from 9.0 to 133.5% in the first year and payback times from 0.7 to 11.1 years. Scenario 8, involving two 5000 L extractors, ethanol recycling, and an annual production of 3,325,300 L of soybean oil at USD 1.25/L, demonstrated the best return on investment (133.5%) in less than one year. Overall, this study suggests that industrial-scale soybean oil extraction via PLE in an intermittent process can be more cost-effective than conventional methods, making implementation feasible. Full article

Glass is one of the most common materials in society, and the float glass process is the main production method of glass used at present, which involves adopting a melting furnace with a single cooler. However, this structure has been difficult to fit to the requirements of modern glass production, such as producing multiple types of glass and large-scale production. Therefore, a large-tonnage float glass melting furnace with a double cooler is studied, which is rising in popularity in the glass sector. The aim of this paper is to clarify the characteristics of the new glass furnace. A numerical simulation technique is applied to analyze the thermal and flow characteristics of molten glass in the new structure so as to clarify the feasibility of production by checking the temperature distribution and flow field of the molten glass. The results show that the new structure also exhibits flow behavior similar to the original structure in the branch line. Due to the addition of the branch line, the stability of the temperature is improved, with a 60 K and 43 K difference between the surface and bottom in the main and branch lines, respectively. Similar stability is shown in the flow field, specifically low acceleration in the cooler (0.006 m/s²). The bubble clarification time is about 2700 s, less than the 3000 s required for flow. The parameters of the branch line meet the requirements of glass production. In theory, a glass-melting furnace with a double cooler has the capacity to produce two types of glass. Full article

In this study, we utilized Selective Laser Melting (SLM) technology to fabricate a magnesium alloy, and subsequently subject it to micro-arc oxidation treatment. We analyzed and compared the microstructure, elemental distribution, wetting angle, and corrosion resistance of the SLM magnesium alloy both before and after the micro-arc oxidation process. The findings indicate that the SLM magnesium alloy exhibits surface porosity defects ranging from 2% to 3.2%, which significantly influence the morphology and functionality of the resulting film layer formed during the micro-arc oxidation process. These defects manifest as pores on the surface, leading to an uneven distribution of micropores with varying sizes across the layer. The surface roughness of the 3D-printed magnesium alloy exhibits a high roughness value of 180 nanometers. The phosphorus (P) content is lower within the film layer compared to the surface, suggesting that the Mg₃(PO₄)₂ phase predominantly resides on the surface, whereas the interior is primarily composed of MgO. The micro-arc oxidation process enhances the hydrophilicity and corrosion resistance of the SLM magnesium alloy, thereby potentially endowing it with bioactivity. Additionally, the increased surface roughness post-treatment promotes cell proliferation. However, certain inherent defects present in the SLM magnesium alloy samples negatively impact the improvement of their corrosion resistance. Full article

In the North Atlantic and the Northern Ocean, from the second half of 2010 to 2014, satellite imagery data showed increased surface water temperatures (in the Icelandic Depression area in September–October 2010, it was 1.3 °C higher than in 2009). The peak of the annual sum of mean monthly ocean surface temperatures near the Icelandic Depression in 2010 (109.3 °C), as well as the negative values of the monthly averaged North Atlantic Oscillation (NAO) indices, estimated in the second half of 2010 and until March 2011, can be explained by the appearance of an additional film of oil origin on the water surface, formed after an oil spill accident at the Deepwater Horizon drilling rig in the Gulf of Mexico. Insufficient evaporative cooling of surface waters near the Icelandic Depression related to the formation of an additive film due to the influence of pollution of the North Sea by oil can explain the earlier peak in the annual sum of mean monthly ocean surface temperatures near the Icelandic Depression in 2003 (107.2 °C). Although global warming is usually ascribed to increased greenhouse gases in the atmosphere, ocean surface water pollution could increase the heat content of the ocean and explain the steady temperature stratification and desalination of these waters due to the melting of Greenland’s glaciers. Thus, when analyzing the concept of global warming, it is necessary to take into account the aspects of pollution of the ocean surface waters to assess the changes in their capacity to accumulate solar radiation, as well as the changes in the heat content of the ocean mixing zone (~200 m). Full article

Introduction of biomass-based nanofillers into the polyamide matrix may represent a sustainable approach for the development of high-performance engineering plastics. From this standpoint, nanocellulose, derived from various cellulosic sources, has attracted a great deal of attention because of is exceptional mechanical properties, lightweight nature, and biodegradability, which presents significant advantages over conventional inorganic fillers. However, a technical challenge arises in the industrially favorable melt processing of polyamides and nanocellulose. This challenge is associated with the thermal degradation of nanocellulose at high processing temperatures, as well as the strong tendency of nanocellulose to aggregate within the polymer matrix. This review examines recent developments to address these issues. Key approaches based on the surface treatment of nanocellulose as well as optimization of processing conditions are discussed in detail, which can provide insights on the development of nanocellulose-reinforced polyamide composites. Full article

The injection molding process is one of the most widely used methods for polymer processing in mass production. Three critical factors in this process include the type of polymer, injection molding machines, and processing molds. Polypropylene (PP) is a widely used semi-crystalline polymer due to its favorable flow characteristics, including a high melt flow index and the absence of a need for a mold temperature controller. Additionally, PP exhibits good elongation and toughness, making it suitable for applications such as box hinges. However, its tensile strength is a limitation; thus, glass fiber is added to enhance this property. It is important to note that the incorporation of glass fiber increases the viscosity of PP. Multi-cavity molds are commonly employed to achieve cost-effective and efficient mass production. The filling challenges associated with geometrically balanced layouts are well documented in the literature. These issues arise due to the varying shear rates of the melt in the runner. High shear rate melts lead to high melt temperatures, which decrease melt viscosity and facilitate easier flow. Consequently, this results in an imbalanced filling phenomenon. This study examines the impact of runner size, gate size, polymer viscosity, and molding process on the filling imbalanced problem in multi-cavity injection molds. Tensile bar injection molding was performed using conventional injection molding (CIM) and microcellular injection molding (MIM) techniques. The tensile properties of the imbalanced multi-cavity molds were analyzed. Flow length within the cavity served as an indicator of the filling imbalance. Additionally, computer simulations were conducted to assess the shear rate’s effect on the runner’s melt temperature. The results indicated that small runner and gate sizes exacerbate the filling imbalance. Conversely, glass fiber-filled polymer composites also contribute to increased filling imbalance. However, foamed polymers can mitigate the filling imbalance phenomenon. Full article

The blast furnace smelting of vanadium–titanium ore plays a crucial role in the efficient utilization of vanadium-titanium resources. In this research, a detailed numerical simulation study of the temperature, velocity, and concentration fields during the smelting process in a vanadium–titanium blast furnace was conducted. The actual production data from a 1750 m³ vanadium–titanium blast furnace was utilized, combined with softening and dripping parameters and material balance calculations, to develop a two-dimensional blast furnace model. This model was employed to analyze the effects of varying smelting intensities on the internal operating conditions of the furnace. The study found that as smelting intensity increased, significant changes occurred in the temperature fields and CO concentration fields within the furnace, thereby affecting the reduction efficiency of the burdens. Additionally, this research also shows that increasing the proportion of Baima pellets in the furnace will lead to the expansion of the soft melting zone and the upward movement of the soft melting zone. This investigation not only revealed the variations in the internal physical fields of the blast furnace under different operating conditions but also provided theoretical foundations and references for optimizing the design and operation of vanadium–titanium blast furnaces. By comparing the velocity field under different smelting intensities, it was found that the difference was small, which was mainly related to the expansion behavior of the pellets. These findings provide an important scientific basis for further improving the efficiency of blast furnace smelting and reducing costs. Full article

The growing demand for more sustainable routes and processes in the mixture separation and purification industry has generated a need to search for innovations, with new solvent alternatives being a possible solution. In this context, a new class of green solvents, known as deep eutectic solvents (DESs), has been gaining prominence in recent years in both academic and industrial spheres. These solvents, when compared to ionic liquids (ILs), are more environmentally friendly, less toxic, low-cost, and easier to synthesize. In addition, they have significantly lower melting points than their precursors, offering a promising option for various applications in this industrial sector. Understanding and studying the thermodynamic behavior of systems composed of these substances in purification and separation processes, such as liquid–liquid extraction and azeotropic distillation, is extremely important. This work aimed to study the phase behavior of liquid–liquid equilibrium (LLE) and vapor–liquid equilibrium (VLE) of water + 1-butanol + DES (choline chloride + glycerol) systems with a molar ratio of 1:2. Experimental LLE data, obtained at 298.15 K and 101.3 kPa, and VLE data, obtained at 101.3 kPa and in the temperature range of 364.05 K–373.85 K, were submitted to the thermodynamic quality/consistency test, proposed by Marcilla et al. and Wisniak, and subsequently modeled using the gamma–gamma approach for the LLE and gamma–phi for the VLE. The non-random two-liquid (NRTL) model was used to calculate the activity coefficient. The results are presented for the VLE in a temperature–composition phase diagram (triangular prism) and triangular phase diagrams showing the binodal curve and tie lines (LLE). The separation and distribution coefficients of LLE were determined to evaluate the extractive potential of the DES. For the VLE, the values of the relative volatility of the system were calculated, considering the entrainer free-basis, to evaluate the presence or absence of azeotropes in the range of collected points. From these data, it was possible to compare DES with ILs as extracting agents, using data from previous studies carried out by the research group. Therefore, the results indicate that the NRTL model is efficient at correlating the fluid behavior of both equilibria. Thus, this study serves as a basis for future studies related to the understanding and design of separation processes. Full article

The synthesis of zeolites from natural aluminosilicate minerals has drawn extensive attention due to its significant utility in greening the zeolite manufacturing process. In this study, pure-phase NaX zeolite was synthesized via a low-temperature hydrothermal method, utilizing natural, low-quality attapulgite clay as the raw material. Acidified clay was fully activated through alkali fusion at 200 °C, and the impact of alkali fusion temperature, H₂O/Na₂O ratio, aging temperature, and crystallization time on the resulting crystalline NaX zeolite was investigated. The optimal conditions for obtaining pure NaX zeolite were determined to be alkali melting at 200 °C for 4 h, an H₂O/Na₂O ratio of 50, aging at 40 °C, and a crystallization period of 11 h at 90 °C. With a large BET surface area of 328.43 m²/g, the obtained NaX zeolite was used to adsorb Pb²⁺ from wastewater with a removal rate of 95%. This research provides a valuable method for the extensive and efficient utilization of low-grade natural attapulgite clay. Moreover, this is the first report on the synthesis of pure-phase NaX zeolite using only low-quality natural attapulgite clay as raw material through an atmospheric pressure water bath method. Full article

Aimed at the problem of gas flurries in carbon dioxide (CO₂) geologic sequestration in the wellbore, this paper proposes a sealing method in which the downhole casing is processed with threaded grooves and then plugged with a low-melting-point alloy plug. Based on this method, a small-scale experimental setup was developed for alloy plug molding and gas sealing in this study. Molding and gas sealing experiments with Sn58Bi alloy plugs inside casings with different surface morphologies were carried out. The gas leakage pathway was determined. The microstructure of the interface between the alloy plug and casing was analyzed using an optical microscope. The influence of the inner surface roughness, threaded groove, length-to-diameter ratio, and ambient temperature on the gas sealing performance of the alloy plugs was analyzed. The experimental results show that, with an increase in ambient temperature, the gas sealing performance of the casing increases significantly; when the inner surface of the casing is processed through threaded grooves, the gas sealing performance is better than with smooth hole casing; the gas sealing performance of the alloy plug presents an obvious linear positive correlation with their length-to-diameter ratio. This research provides theoretical support for downhole CO₂ plugging using Sn58Bi in the casing. Full article

This work reports the synthesis method and various properties of four rod-like antiferroelectric (R) laterally substituted enantiomers, with or without fluorine atoms used as substituents in the benzene ring. The influence of fluorine substitution on the mesophase temperature range was determined. The synthesized compounds are three-ring rod-like smectics with a chiral center based on (R)-(−)-2-octanol. Their chemical and optical purity was checked using high-performance liquid chromatography (HPLC). Two newly synthesized enantiomers and three previously reported (R) enantiomers were used to formulate two antiferroelectric mixtures. The mesomorphic behavior was characterized by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction (XRD). The helical pitch and tilt angle measurements were done using the selective light reflection phenomenon and the electro-optical method, respectively. All the enantiomers exhibit a wide temperature range of the antiferroelectric phase, with a high tilt angle. Furthermore, the enantiomer with lateral fluorine substitution in the ortho position has a very long helical pitch (more than 2.0 µm), relatively low enthalpy of melting point, and a tilt angle close to 45 degrees. The designed (R) enantiomers can be useful for formulating eutectic mixtures for further use in various devices, including photonics and optoelectronics. Full article

Waste slag and rubber particles are commonly used to modify concrete, offering benefits such as reduced cement consumption and lower greenhouse gas emissions during cement production. In this study, these two environmentally friendly, sustainable waste materials were proposed for the preparation of mortar intended for snow-melting pavements. A series of experiments were conducted to evaluate the performance of the material and to determine whether its compressive and flexural strengths meet the requirements of pavement specifications. The mortar’s suitability for snow-melting pavements was assessed based on its thermal conductivity, impermeability, and freeze–thaw resistance. The results indicate that slag, when used in different volume fractions, can enhance the compressive and flexural strength of the mortar. Slag also provides excellent thermal conductivity, impermeability, and resistance to freeze–thaw cycles, contributing to the overall performance of snow-melting pavements. When the slag content was 20%, the performance was optimal, with the compressive strength and flexural strength reaching 58.5 MPa and 8.1 MPa, respectively. The strength loss rate under freeze–thaw cycles was 8.03%, the thermal conductivity reached 2.2895 W/(m * K), and the impermeability pressure value reached 0.5 MPa. Conversely, the addition of rubber particles was found to decrease the material’s mechanical and thermal properties. However, when used in small amounts, rubber particles improved the mortar’s impermeability and resistance to freeze–thaw cycles. When the rubber content was 5% by volume, the impermeability pressure value reached 0.5 MPa, which was 166.7% lower than that of ordinary cement mortar. Under freeze–thaw cycles, the strength loss rate of the test block with a rubber content of 25% volume fraction was 9.83% lower than that of ordinary cement mortar. Full article

Personal thermal management materials integrated with phase-change materials have significant potential to satisfy human thermal comfort needs and save energy through the efficient storage and utilization of thermal energy. However, conventional organic phase-change materials in a solid state suffer from rigidity, low thermal conductivity, and leakage, making their application challenging. In this work, polyethylene glycol (PEG) was chosen as the phase-change material to provide the energy storage density, polyethylene oxide (PEO) was chosen to provide the backbone structure of the three-dimensional polymer network and cross-linked with the PEG to provide flexibility, and carbon nanotubes (CNTs) were used to improve the mechanical and thermal conductivity of the material. The thermal conductivity of the composite fiber membranes was boosted by 77.1% when CNTs were added at 4 wt%. Water-resistant modification of the composite fiber membranes was successfully performed using glutaraldehyde-saturated steam. The resulting composite fiber membranes had a reasonable range of phase transition temperatures, and the CC₄PCF-55 membranes had melting and freezing latent heats of 66.71 J/g and 64.74 J/g, respectively. The results of this study prove that the green CC₄PCF-55 composite fiber membranes have excellent flexibility, with good thermal energy storage capacity and thermal conductivity and, therefore, high potential in the field of flexible wearable thermal management textiles. Full article

The geometric shape, symmetry, and topology of colloidal particles often allow for controlling colloidal phase behavior and physical properties of these soft matter systems. In liquid crystalline dispersions, colloidal particles with low symmetry and nontrivial topology of surface confinement are of particular interest, including surfaces shaped as handlebodies, spirals, knots, multi-component links, and so on. These types of colloidal surfaces induce topologically nontrivial three-dimensional director field configurations and topological defects. Director switching by electric fields, laser tweezing of defects, and local photo-thermal melting of the liquid crystal host medium promote transformations among many stable and metastable particle-induced director configurations that can be revealed by means of direct label-free three-dimensional nonlinear optical imaging. The interplay between topologies of colloidal surfaces, director fields, and defects is found to show a number of unexpected features, such as knotting and linking of line defects, often uniquely arising from the nonpolar nature of the nematic director field. This review article highlights fascinating examples of new physical behavior arising from the interplay of nematic molecular order and both chiral symmetry and topology of colloidal inclusions within the nematic host. Furthermore, the article concludes with a brief discussion of how these findings may lay the groundwork for new types of topology-dictated self-assembly in soft condensed matter leading to novel mesostructured composite materials, as well as for experimental insights into the pure-math aspects of low-dimensional topology. Full article