Semi-solid State Research Articles

Particle phase state and aerosol liquid water greatly impact secondary aerosol formation: insights into phase transition and its role in haze events

Abstract. The particle phase state is crucial for reactive gas uptake, heterogeneous, and multiphase chemical reactions, thereby impacting secondary aerosol formation. This study provides valuable insights into the significance of particle-phase transition and aerosol liquid water (ALW) in particle mass growth during winter. Our findings reveal that particles predominantly exist in a semi-solid or solid state during clean winter days with ambient relative humidity (RH) below 30 %. However, a non-liquid to liquid phase transition occurs when the ALW mass fraction exceeds 15 % (dry mass) at transition RH thresholds of 40 %–60 %. During haze episodes, the transformation rates of sulfate and nitrate aerosols rapidly increase through phase transition and increased ALW by 48 % and 11 %, respectively, resulting in noticeable increases in secondary inorganic aerosols (SIA). The presence of abundant ALW, favored by elevated RH and higher proportion of SIA, facilitates the partitioning of water-soluble compounds from the gas to the particle phase, as well as heterogeneous and aqueous processes in liquid particles. This leads to a substantial increase in the formation of secondary organic aerosols and elevated aerosol oxidation. Consequently, the overall hygroscopicity parameters exhibit a substantial enhancement, with a mean value of 23 %. These results highlight phase transition as a key factor initiating the positive feedback loops between ALW and secondary aerosol formation during haze episodes over the North China Plain. Accurate predictions of secondary aerosol formation necessitate explicit consideration of the particle phase state in chemical transport models.

Chemical composition and storage temperature influence on textural characteristics of bakery fats derived from plant sources

Abstract Edible fats obtained from plant sources, characterized by their higher proportion of saturated fatty acids, typically exist in solid or semi-solid states and present different physical properties. The quality of solid or semi-solid vegetable edible fats plays a crucial role in the food production sector and for consumers alike. Attributes such as fat hardness and spreadability are significant factors for both industry and consumers, as these textural properties are directly influenced by the constituents of the fats. The chemical composition and fatty acid content of fats derived from plant sources correlated with textural characteristics such as hardness, plasticity, adhesiveness, viscosity, and also spreadability properties were investigated. The total color differences of fat samples varied from 7.06 to 45.50. Among the saturated fatty acids, palmitic acid occurred as the predominant one across palm oil, and margarine samples, while the most abundant monounsaturated fatty acid was oleic acid with an average of 36.41% for palm oil and 26.46% for margarine samples. The puncture test performed with three different penetrometers, and the spreadability test, conducted at two different temperatures, showed a differentiation of the analyzed fat samples.

Sulfonated hydrogel electrolyte enables dendrite-free zinc-ion batteries

Metallic Zn anode is plagued by severe side reactions and dendrite growth, preventing the commercial development of Zn-ion batteries (ZIBs). Semi-solid state hydrogel electrolyte has received immense attention in aqueous Zn-ion batteries due to their intrinsic advantages (e.g., wider electrochemical windows, good interfacial compatibility, and multi-functional applications). However, their inferior ionic conductivity and mechanical deformation tolerance are the main barriers to realizing the true application in ZIBs. Herein, a hydrogel electrolyte with high ionic conductivity and high flexibility is fabricated through sulfonated chitosan and further cross-linking with polyacrylamide. Accordingly, the ion conductivity of the hydrogel electrolyte increases from 28.2 to 38.1 mS cm−1, whilst tensile strength is elevated from 19.1 to 54.2 kPa. With this hydrogel electrolyte, the Zn||Zn symmetric cells show exceptional cycle stability over 2600 h at the current density of 1 mA cm−2, and the Zn||Cu asymmetric cells demonstrate nearly 100 % coulomb efficiency over 1200 cycles. In addition, NH4V4O10||Zn full cells enable capacity retention of as high as 96.1 % even over 500 cycles, and the as-assembled flexible batteries can stand bending, twisting, and cutting operation without comprising the electrochemical performance.

Comparative analysis of Chrysoporthe cubensis exoproteomes and their specificity for saccharification of sugarcane bagasse

The phytopathogenic fungus Chrysoporthe cubensis is a relevant source of lignocellulolytic enzymes. This work aimed to compare the profile of lignocellulose-degrading proteins secreted by C. cubensis grown under semi-solid state fermentation using wheat bran (WB) and sugarcane bagasse (SB). The exoproteomes of the fungus grown in wheat bran (WBE) and sugarcane bagasse (SBE) were qualitative and quantitatively analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC–ESI–MS/MS). Data are available via ProteomeXchange with identifier PXD046075. Label-free proteomic analysis of WBE and SBE showed that the fungus produced a spectrum of carbohydrate-active enzymes (CAZymes) with exclusive characteristics from each extract. While SBE resulted in an enzymatic profile directed towards the depolymerization of cellulose, the enzymes in WBE were more adaptable to the degradation of biomass rich in hemicellulose and other non-lignocellulosic polymers. Saccharification of alkaline pre-treated sugarcane bagasse with SBE promoted glucose release higher than commercial cocktails (8.11 g L−1), while WBE promoted the higher release of xylose (5.71 g L−1). Our results allowed an in-depth knowledge of the complex set of enzymes secreted by C. cubensis responsible for its high lignocellulolytic activity and still provided the identification of promising target proteins for biotechnological applications in the context of biorefinery.

Optimization of the Media and Plant Growth Regulators for Clonal Propagation of Adansonia digitata L.: An Endangered Tree

This research carried out to evaluate the influence of different nutrient media, specifically Murashige and Skoog (MS), Anderson medium (AM), and Woody Plant Medium (WPM), in both liquid and semisolid forms, on the in vitro growth of shoots and roots in Adansonia digitata (baobab) using nodal segments as the starting explants. These media were supplemented with varying concentrations of two plant growth regulators, NAA (0.1-1.0 mg/l) and BAP (0.2-2.0 mg/l).The results of the study demonstrated that Adansonia digitata explants exhibited the highest increase in both the number and length of shoots when cultured on MS medium with a combination of NAA (0.3 mg/l) and BAP (0.5 mg/l) in a semisolid state. The average number of shoots reached 3.8±2.33, and their average length was 2.3±2.00 cm. Plantlets grown on MS medium exhibited well-developed leaves and shoots.Further experiments were conducted with in vitro shoots, exploring various concentrations of the auxin NAA and cytokinins BAP, TDZ, and KN on MS medium. The findings indicated that BAP and NAA were more effective in promoting shoot proliferation compared to the other tested hormones. The combination of BAP (0.5 mg/l) and NAA (0.2 mg/l) significantly improved the shoot proliferation rate, with the highest percentage (60.4%) and the greatest number of regenerated shoots (4.8±2.33) observed on MS medium.In contrast, plantlets cultured in both AM and WPM media displayed lower averages for shoot and root numbers and lengths compared to those grown on MS medium. The maximum number of roots (3.1±1.66) was obtained when MS medium was augmented with IBA at a concentration of 1.0 mg/l.Subsequently, the produced plantlets were gradually transferred to pots filled with a mixture of perlite and cocopeat in a 1:3 ratio and placed in a greenhouse for further growth.

Palm oil as an alternative bio lubricant: A review

Lubrication in mechanical operations involving relative motions of machine elements have been known to facilitate longer techno-economic life span of machine and its components. Lubrication reduces wear and tear of contacting surfaces in relative motion by creating a lubricous layered gap of fluid, powder or semi-solid like grease. Lubricant has also been proven to move heat away from rubbing surfaces to enhance thermal stability of their operations. Various methods, substances and technologies have been adopted to achieve the desired smooth running, minimize frictional losses and improve the thermal stability in the machine members. Mineral oils of long chain hydrocarbon as base oil have really gained ground as an extremely popular choice either in liquid or semi-solid state as lubricant. Recent research has however revealed that mineral oils are non-biodegradable, prone to pollution and hence constitute enormous risks to the environment. This observation and the need for a friendly environment have aroused the curiosity of researchers in the field of tribology and material engineering to the onerous challenge of finding alternative lubricants that will be harmless to the ecosystem and easy disposal of after use. Chief amongst the suggestions made towards the discovery of an environmentally friendly lubricant is the use of vegetable oils of distinct species. The identification of the potential available in vegetable oils has been demonstrated in certain classical operations requiring moderate temperature such as machining and few other cold working operations. This review examines the previous studies regarding the discovery of an alternative machine lubricant from the available vegetative seed oils, particularly palm oil, and suggests ways to improve previous findings and potentials.

Predicting Atmospheric Particle Phase State Using an Explainable Machine Learning Approach Based on Particle Rebound Measurements.

The particle phase state plays a vital role in the gas-particle partitioning, multiphase reactions, ice nucleation activity, and particle growth in the atmosphere. However, the characterization of the atmospheric phase state remains challenging. Herein, based on measured aerosol chemical composition and ambient relative humidity (RH), a machine learning (ML) model with high accuracy (R2 = 0.952) and robustness (RMSE = 0.078) was developed to predict the particle rebound fraction, f, which is an indicator of the particle phase state. Using this ML model, the f of particles in the urban atmosphere was predicted based on seasonal average aerosol chemical composition and RH. Regardless of seasons, aerosols remain in the liquid state of mid-high latitude cities in the northern hemisphere and in the semisolid state over semiarid regions. In the East Asian megacities, the particles remain in the liquid state in spring and summer and in the semisolid state in other seasons. The effects of nitrate, which is becoming dominant in fine particles in several urban areas, on the particle phase state were evaluated. More nitrate led the particles to remain in the liquid state at an even lower RH. This study proposed a new approach to predict the particle phase state in the atmosphere based on RH and aerosol chemical composition.

Quantifying the Viscosity of Individual Submicrometer Semisolid Particles Using Atomic Force Microscopy.

Atmospheric aerosols' viscosities can vary significantly depending on their composition, mixing states, relative humidity (RH) and temperature. The diffusion time scale of atmospheric gases into an aerosol is largely governed by its viscosity, which in turn influences heterogeneous chemistry and climate-relevant aerosol effects. Quantifying the viscosity of aerosols in the semisolid phase state is particularly important as they are prevalent in the atmosphere and have a wide range of viscosities. Currently, direct viscosity measurements of submicrometer individual atmospheric aerosols are limited, largely due to the inherent size limitations of existing experimental techniques. Herein, we present a method that utilizes atomic force microscopy (AFM) to directly quantify the viscosity of substrate-deposited individual submicrometer semisolid aerosol particles as a function of RH. The method is based on AFM force spectroscopy measurements coupled with the Kelvin-Voigt viscoelastic model. Using glucose, sucrose, and raffinose as model systems, we demonstrate the accuracy of the AFM method within the viscosity range of ∼104-107 Pa s. The method is applicable to individual particles with sizes ranging from tens of nanometers to several micrometers. Furthermore, the method does not require prior knowledge on the composition of studied particles. We anticipate future measurements utilizing the AFM method on atmospheric aerosols at various RH to aid in our understanding of the range of aerosols' viscosities, the extent of particle-to-particle viscosity variability, and how these contribute to the particle diversity observable in the atmosphere.

Mechanical properties and micro-structural of Al-Zn-Mg-Cu alloy by semi-solid SIMA processed

This paper investigates the microstructure and mechanical behavior of 7050 aluminum alloy during semi-solid process. The semi-solid process involves multi-directional forging at 300 °C, and followed by semi-solid treatment at 590–630 °C for 10–30 min. The microstructure was characterized by scanning electron microscopy, X-ray diffraction, electron back scattered diffraction and transmission electron microscopy. There are many copper enriched at grain boundaries during isothermal treatment. It also can be seen that the reduce of Mg, Zn and Cu are inside the grain clearly. The mechanical properties of different treated samples in semi-solid state were studied by tensile test. The results show that the tensile strength and yield strength of the material decrease with the increase of holding time and due to its internal solid-liquid changes.

Optimized V‐Doped Defective TiO2/α‐(Fe2O3)1‐x(Cr2O3)x Heterojunctions for Photo‐Assisted Supercapacitor Devices: Insights on the Materials Integrity and Dual Conversion‐Storage Mechanism

AbstractEnergy conversion and storage integrated power units suffer from multiple engineering issues. Replacing two devices (solar cell and supercapacitor assembly) with one device (photo‐enhanced supercapacitor‐ PSC) requires materials with emerged dual solar‐electrochemical storage attributes. Herein, a propitious approach is developed to fabricate all visible light‐enhanced semisolid flexible PCS. Nanoflakes‐based p‐n junction α‐(Fe2O3)1‐x(Cr2O3)x photocathode is synthesized directly on industrial waste stainless steel mesh (316L‐SS). Alongside, three TiO2‐based electrodes are utilized as positive photoactive electrodes. Tuning the optical properties of TiO2 is displayed via doping with mixed valence vanadium (V4+/V5+) together with thermal hydrogen annealing. This is revealed via the reduction of the bandgap energy from 2.89 to 2.15 eV, which can be ascribed to the induced oxygen vacancies. The device can sustain up to 1.6 V potential window with 91% stability after 350 successive charge/discharge cycles with the possibility of performance regeneration to its 100% retention. An illustration of the photo‐storage mechanism is proposed based on the X–ray photoelectron spectroscopy, X–ray crystallography, and band position/alignment results. Quasi‐reversible water splitting/formation is concluded as the main storage mechanism in the semisolid state electrolyte under illumination conditions.

Nonequilibrium Behavior in Isoprene Secondary Organic Aerosol.

Recent studies have shown that instantaneous gas-particle equilibrium partitioning assumptions fail to predict SOA formation, even at high relative humidity (∼85%), and photochemical aging seems to be one driving factor. In this study, we probe the minimum aging time scale required to observe nonequilibrium partitioning of semivolatile organic compounds (SVOCs) between the gas and aerosol phase at ∼50% RH. Seed isoprene SOA is generated by photo-oxidation in the presence of effloresced ammonium sulfate seeds at <1 ppbv NOx, aged photochemically or in the dark for 0.3-6 h, and subsequently exposed to fresh isoprene SVOCs. Our results show that the equilibrium partitioning assumption is accurate for fresh isoprene SOA but breaks down after isoprene SOA has been aged for as short as 20 min even in the dark. Modeling results show that a semisolid SOA phase state is necessary to reproduce the observed particle size distribution evolution. The observed nonequilibrium partitioning behavior and inferred semisolid phase state are corroborated by offline mass spectrometric analysis on the bulk aerosol particles showing the formation of organosulfates and oligomers. The unexpected short time scale for the phase transition within isoprene SOA has important implications for the growth of atmospheric ultrafine particles to climate-relevant sizes.

Effects of Heating Rates on Microstructural Evolution of Hot Extruded 7075 Aluminum Alloy in the Semi-Solid State and Thixotropic Deformation Behavior.

The non-dendritic microstructure plays a crucial role in determining the rheological properties of semi-solid alloys, which are of the utmost importance for the successful industrial application of the thixoforging process. To further understand the impact of the reheating process on the evolution of microstructure and thixotropic deformation behavior in the semi-solid state, a hot extruded and T6 treated 7075 aluminum alloy was reheated to the selected temperature ranges using varying heating rates. Subsequently, thixo-compression tests were performed. The study found that during reheating and isothermal holding, the elongated microstructure of the as-supplied alloy can transform into equiaxed or spherical grains. The presence of recrystallized grains was found to be closely linked to the penetration of the liquid phase into the recrystallized grain boundaries. Furthermore, it was observed that higher heating rates resulted in smaller grain sizes. The thixotropic flow behavior of the alloy with various microstructures was analyzed using the true stress-strain curves obtained by thixo-compression experiments, which exhibited three stages: a rapid increase in true stress to a peak value, followed by a decrease in true stress and a steady stress until the end of compression. The stress fluctuated with strain during the formation of the slurry at a strain rate of 10 s-1, indicating the significant role of strain rate in material flow during semisolid formation.

Evaluation of Quality Parameters of Light Sensitive Drugs Marketed in Nepal.

Photosensitivity is the response of drug or drug product to the exposure of solar, UV and visible light in the solid, semisolid, or liquid state that leads to a physical or chemical change. Exposure to light is a concern with numerous medications due to the potential for photo degradation or other chemical reactions that affect drug stability. Out of all the registered brands in Department of Drug Administration, 9 brands of Rabeprazole tablets, 5 brands of Promethazine tablets and 5 brands of methylcobalamin tablets were selected and were subjected for testing and analysis for various quality parameters as per pharmacopoeia. The labels of the collected medicine were analyzed. The obtained data were entered and analyzed in Microsoft office excel 2019. Eleven products did not comply with the existing regulatory requirement on labeling system of medicine as per Regulation of Standard of drugs. There was no uniformity in mentioning the self-life. Similarly, large variation was seen on price of same generic drugs. Information regarding storage conditions, direction for use and category of the drug were lacking in the label of some brands of medicines.Upon Laboratory analysis, two brands of promethazine tablets and three brands of Rabeprazole tablets were found substandard. Drug content of all the brands of Methylcobalamin was found to contain overage. The result of this study indicates that substandard medicines are abundant in Nepalese market. There is weak regulation monitoring which have resulted in no uniformity in similar pharmaceutical products too. Hence, stringent regulatory monitoring is required to assessthe quality of pharmaceutical products in the Nepalese market.

Isotropic Pressure Membrane Sensor to Establish Shrinkage Stress Evolution in Clayey Soil

Abstract The shrinkage behavior of clay has been identified to have a significant influence on many geotechnical problems that include foundation failure, slope instability, damages in buried pipelines, crack formation in liner systems, etc. In this context, researchers have focused on understanding and quantifying the effect of shrinkage behavior of fine-grained soils in terms of volumetric shrinkage and crack propagation. But it has been realized that shrinkage stresses would also develop in fine-grained soil mass in tandem with volumetric shrinkage owing to tensile stresses and particle rearrangement. This necessitates mapping shrinkage stress evolution in clayey soils of distinct mineralogical and plasticity characteristics. Under these circumstances, the authors have developed a novel isotropic pressure monitoring device (I-PMD) and test protocols to measure shrinkage stress in clayey soil. The results obtained from the present study demonstrate the efficacy of employing I-PMD for establishing (i) soil shrinkage stress curve and (ii) maximum shrinkage stress σsmax of clayey soils while drying. From the present study, it has been inferred that the shrinkage stress initiation point is dependent on its liquid limit, and also, a steady increase in stress generation has been identified in its semisolid state. The result obtained from the experimental studies has been utilized to establish the empirical relationship to estimate shrinkage stress from clay characteristics.

Constructing a core-shell structure in Ti-based alloys with exceptional mechanical properties through semi-solid sintering

In this work, we developed a semi-solid sintering method for constructing a core-shell architecture in Ti68.8Nb13.6Co6.8Cr5.1Al6.5 alloy and revealed the underlying mechanism of microstructure evolution and deformation behavior. Fundamentally, the semi-solid state was achieved by sintering amorphous powders at temperatures between the melting point of the CoTi2 phase and the β-Ti matrix. During the process, the liquid CoTi2 phase was squeezed towards the β-Ti boundaries due to the sintering pressure and the growth of β-Ti grains. Subsequently, it transformed into a hard ultrafine CoTi2 phase distributed along the β-Ti boundaries, constructing a core-shell structure. The resulting core-shell structure exhibited a high compressive yield strength of 1560 MPa, an ultimate strength of 3006 MPa, and a remarkable compressive strain of 40.1%, surpassing typical Ti-based alloys under compressive loading. The high strength was attributed to dislocation-impeding effect of the CoTi2 phase, while the activation of multiple slip systems triggered by the CoTi2 shell contributed to plasticity. The results provide fundamental insights into the fabrication of Ti-based alloys with exceptional mechanical properties for structural materials applications.

High Speed Roll Casting of Al-5%Mg Strip at Semisolid Condition

Semisolid Al–Mg alloy strips were cast using high-speed twin-roll casting under very low roll loads to investigate the effect of low roll loads on surface cracking and center segregation of Mg. In the conventional twin-roll caster for aluminum alloys, the roll speed is usually less than 2 m/min, and the roll load is typically greater than 1 kN/mm to solidify the aluminum alloy and reduce casting defects. In the vertical type high-speed twin-roll caster, the roll speed can range from 10 to 90 m/min, and strips can be cast at roll loads below 500 N/mm, down to loads as low as 2 N/mm. Strips cast at 2 N/mm in this study did not completely solidify when released from the rolls; this means that the strips were semisolid. Al–Mg strips can be continuously cast without breaking when they are semisolid. The surface cracking and center segregation of these strips were compared with those of strips cast at a higher load of 88 N/mm. The effect of the small load on the presence of Mg at cross sections of the strip was investigated using etching with Weck’s reagent.

Flow Length Influence of Cores Made of High-Temperature Composite in Semi-Solid AZ91 Produced in Thixomolding

Die casting of metallic materials is a highly economical manufacturing process for producing complex functionally integrated components close to the final shape. Thixomolding of magnesium alloys is a special process of die casting. In this process, the magnesium alloy granulate is brought to a semi solid state in a screw conveyor and then injected into the mould. The production of the casting material in the Thixomolding screw allows the temperature conditions to be set for thermally controlled solid content. These are produced by heating the Mg granulate above solidus temperature and have significantly lower casting temperature compared to conventional die casting.In this study, a flow length tool for semi solid AZ91 is designed and flow length tests are performed. Also the general use of a composite material cores in semi-solid magnesium Thixomolding and their influence on flow length are investigated. Cast-in cores allow the reproduction of complex internal hollow geometries of castings or the integration of special materials.

Rheological Behavior in the Semisolid State of Al-Si-Cu Alloys Produced by ECAP

It is fundamental in thixoforming to have a refined microstructure that, when heated to the semisolid state, consists of a mixture of small spheres immersed in liquid as this ensures the best rheological properties. The present work therefore aims to analyze the rheological behaviour of aluminum-silicon-copper alloys, namely, Al5Si2.8Cu, Al6Si2.8Cu and Al7Si2.8Cu. The alloys were produced by conventional casting and then deformed by ECAP in one pass in a die containing two channels of the same cross-sectional area forming an angle of 120°. After being processed by ECAP, the alloys were heated to semisolid temperatures, i.e., temperatures corresponding to a solid fraction of 45 %, and kept in the semisolid state for 0, 30 and 90 s, after which they were subjected to hot compression tests. The structures of the three alloys had an excellent response to recovery and recrystallization mechanisms, with refined microstructures that led to the formation of very fine spheres immersed in liquid in the semisolid state. The best rheological behaviour was obtained for the Al5Si2.8Cu alloy, which had an apparent viscosity of the order of 103 Pa.s. The findings suggest that this simple ECAP process is a promising route for the production of semisolid feedstock for use in thixoforming.

Rheological Behaviour of Secondary AlSi7Mg Alloy for Semi-Solid Processing

Semisolid castings are usually produced using primary Al alloys to ensure significant mechanical performances. However, the need to increase the use of secondary alloys is becoming more and more urgent to reduce the carbon footprint of the manufacturing process. In fact, it is well known that the production of primary alloys is far more demanding in terms of energy and emissions than the recycling route. To extend the use of secondary alloys to semisolid processing, it is necessary to thoroughly understand their properties and how they can influence a material with peculiar properties as the semisolid one. Besides microstructural and mechanical features, the rheological behaviour also plays a major role when dealing with processing metals in the semisolid state. Therefore, in the present study, a rheological characterization of secondary AlSi7Mg commercial alloy was carried out and compared to that of the conventional primary alloy. In details, a different content of Fe, Cu and Mn was considered, as these impurities easily form primary intermetallic particles, which can remain dispersed in the liquid matrix of the semisolid metal. The aim of this work is to understand if this can affect the rheological properties of the considered semisolid alloy. Flow curves and yield stresses were obtained from the experimental results to compare the behaviour of the different alloys.

Semi-Solid Deformation Behavior, Flow Stress Prediction and Deformed Microstructure of GH3536 Superalloy

In current work, the deformation behavior and deformed microstructures of GH3536 superalloy in semi-solid state were investigated, and the semi-solid flow stress was predicted by artificial neural network (ANN) model. The semi-solid compression deformation was carried out at 1320-1350 °C, and the solid deformation behavior at 1200 °C was tested for comparison. The peak stress under 0.01-1 s-1 semi-solid deformation was 45.6-161.9 MPa. The peak stress decreased with the increase of deformation temperature and the decrease of strain rate. The ANN model could well describe semi-solid flow stress. During semi-solid deformation, the apparent viscosity dropped as shear rate increased. At high temperature and low strain rate, more liquid phase was distributed at grain boundaries. The solid grains coarsened as deformation temperature increased.