Search Results (58)

Background: Existing therapies for xerostomia are primarily symptomatic, providing temporary mucosal hydration without addressing underlying pathological changes in the oral cavity. In this context, medicated chewing gums containing ascorbic acid and lysozyme hydrochloride offer a promising approach, combining antimicrobial, antioxidant, and trophic effects with physiological salivary stimulation and prolonged local delivery. Methods: For the development of compressed chewing gum formulation, the physicochemical (particle size distribution, moisture absorption capacity, and microscopic characteristics) and technological (flowability, angle of repose, bulk and tapped density, Carr’s index (CI), and Hausner ratio (HR)) properties of the active substances and their formulations with excipients were evaluated. Pharmacological activity was assessed in an atropine-induced xerostomia rat model. Results: The physical mixture of all components showed inferior flow properties compared with the formulation containing pre-granulated lysozyme hydrochloride, as evidenced by higher Carr’s index and Hausner ratio values (CI = 17, HR = 1.20 vs. CI = 13, HR = 1.14), indicating improved processability after pre-granulation. The effect of relative humidity during formulation was also assessed, with an optimal level of 40% required to ensure process stability due to the hygroscopic nature of the components. Based on these data, technological approaches ensuring processability were established, including wet pre-granulation of lysozyme hydrochloride and premixing of ascorbic acid to reduce oxidation risk. These approaches resulted in an optimized compression mass with excellent flowability (CI = 8, HR = 1.09), suitable for the preparation of medicated chewing gum. An optimal compression force (7 kN) ensured suitable rheological and textural properties, resulting in rapid and nearly complete release of the active ingredients from the medicated chewing gum, consistent with kinetic analysis. In vivo studies using an atropine-induced xerostomia rat model demonstrated that the combination of ascorbic acid and lysozyme hydrochloride significantly increased salivary secretion (2.17-fold vs. control pathology group) and reduced salivary gland mass coefficients (by 13–18% compared with the control pathology group and groups receiving individual active ingredients), alongside improvement of oxidative stress markers, including a reduction in TBA-reactants (by 51.6%) and an increase in catalase activity (by 51.0%). Conclusions: The developed medicated chewing gum showed favorable technological properties, efficient release of active ingredients, and anti-xerostomic activity in vivo, indicating its potential for xerostomia relief and oral health support. Full article

As an efficient dry separation technology, electrostatic separation exhibits significant potential for application in the sorting and recovery of carbon-rich resources from coal gasification fine slag (CGFS). The small particle size and high moisture content of CGFS particles are the main factors affecting the efficiency of separation. This study proposes a method integrating particle moisture reduction and charging promotion based on molecular sieves, with the aim of investigating its feasibility in improving the electrostatic separation efficiency of CGFS particles. The results indicate that molecular sieves can effectively adsorb moisture from the ambient humid air and the surface of particles, allowing for rapid drying of wet particles. The reduction in moisture content on the particle surfaces significantly promotes their charging capability, creating favorable conditions for electrostatic separation. After molecular-sieve-assisted charging enhancement, the carbon content in the ash-enriched positive plate product decreased by 4.96%, while the carbon content in the carbon-enriched negative plate product increased by 12.15%, indicating a significant improvement in carbon–ash separation efficiency. Correspondingly, the decarbonization efficiency of the positive plate and carbon recovery efficiency of the negative plate were increased by 21.30% and 52.17%, respectively. Furthermore, when the moisture content exceeds 10%, the phenomenon of inter-particle agglomeration can adversely affect the separation of carbon and ash particles. The most suitable operating conditions are a moisture content no higher than 10%, an electric field density of 30 kV/m, a filling molecular sieve of 400 g, and a gas velocity of 12 m/s (volumetric flow rate 84.78 m³/h). In practical industrial applications, it is advisable to consider pre-treating the particles for drying or employing secondary separation to enhance sorting accuracy. Full article

Increasing constraints related to water consumption and operational complexity have intensified interest in dry coal beneficiation as an alternative to conventional wet cleaning, particularly for low-calorific coals used in thermal power plants. In this study, the performance of a gravity-based dry beneficiation process using an air table was experimentally investigated for run-of-mine coals from the Soma Coal Basin, utilized in the Soma A Thermal Power Plant. The coal was crushed to −10 mm and classified into three size fractions, 5–10 mm, 3–5 mm, and 1–3 mm, before beneficiation. A pilot-scale air table with a capacity of 10 t/h was employed, and operating parameters including table inclination, airflow rate, and vibration frequency were optimized for each size fraction. Clean coal yields of 86.8–88.7% were achieved, while the ash content was reduced from 32 to 35% in the feed to 27.8%–29.7% in the clean coal (dry basis), remaining within the acceptable ash limits of the boiler design. The reject fractions exhibited high ash contents of approximately 71%–72%, indicating effective de-stoning and removal of high-density gangue minerals. Low and consistent E_p values (0.05–0.06) together with nearly constant cut-point densities (D₅₀ ≈ 1.82%–1.83 g/cm³) demonstrated sharp and stable density-based separation. The dust fraction remained limited (1.4%–2.1%), confirming mechanically stable operation. The removal of approximately 10% of the feed as high-density reject was found to reduce coal milling energy demand and lower the energy consumption of ash handling and disposal systems. Overall, the results show that air table-based dry beneficiation enables water-free and energy-efficient pre-concentration of low-calorific coals, offering strong potential for application in water-scarce regions. Full article

To elucidate the modification and pre-swelling mechanisms of instant bituminous modifiers and their contribution to bituminous materials’ performance, this study investigates an instant ultra-high-performance bitumen modifier (SHVE-M). Fluorescence microscopy (FM), gel permeation chromatography (GPC), physical property tests, viscoelastic properties tests, dynamic shear rheometer (DSR), and mixture pavement performance tests were employed to systematically characterise the instant modified bitumen (SHVE-MB) and its mixture (SHVE-MBM). The results indicate that SHVE-M forms a stable “bitumen phase–polymer spherical phase” structure. ImageJ-win64 analysis revealed that SHVE-M exhibits a modifier area fraction of 46.68% and an average area fraction of 0.22‰, while SHVE-MB achieves a modifier area fraction of 17.54% and an average area fraction of 0.18‰. This morphology is supported by a large molecular size (LMS) content of 43% in SHVE-M. In terms of physical properties, the SHVE-MB (prepared via 10 min shearing) exhibited a penetration of 46.2 dmm, a softening point of 91.7 °C, and a ductility of 34.3 cm. These values are highly comparable to the conventional wet-process HVE-MB (prepared via 4 h maturation), with negligible differences of 0.5 dmm, 1.7 °C, and 1.4 cm, respectively. Quantitatively for viscoelasticity, SHVE-MB achieved a dynamic viscosity of 425,283.4 Pa·s at 60 °C and an elastic recovery rate of 92.1%, paralleling the 414,623.7 Pa·s and 93.6% of HVE-MB. Regarding mixture performance, the high-temperature dynamic stability (DS) of SHVE-MBM reached 7974 times/mm, approaching the 8256 times/mm of HVE-MBM. The water stability was excellent with a splitting tensile strength ratio (TSR) of 97.4% (vs. 98.0% for HVE-MBM). Furthermore, the low-temperature fracture toughness (K_IC) reached 39.8 N/mm^1.5, significantly outperforming SBS-MBM (27.9 N/mm^1.5) and remaining close to HVE-MBM (43.9 N/mm^1.5). These findings indicate that SHVE-MB effectively bridges the performance gap between instant and traditional high-viscosity modified bitumen, and the pre-swelling mechanism of SHVE-M is well characterized in this study. Full article

Biofouling, the undesirable deposition of microorganisms on surfaces, is ubiquitous in aqueous systems. This is no different for systems running with water-miscible metalworking fluids (MWFs), which additionally contain many organic chemicals that create favorable conditions for growth and metabolism. Biofilm formation is thus inevitable, as there is no shortage of wetted surfaces in metalworking systems. MWF manufacturers tried in vain to offer resistance by using biocides and biostatic compounds as ingredients in concentrates and as tank-side additives. We report here that such elements, alone or as components of MWFs, did not prevent biofilm formation and had negligible effects on pre-established laboratory biofilms. Moreover, biofilms in metalworking systems are interwoven with residues, sediments, and metal swarfs generated during machining. Again, co-incubation of such “real” biofilms with MWFs had no significant effect on population size—but on population composition! The implications of this finding are unclear but could provide a starting point for the treatment of biofouling, as biofilm population structure might be of importance. Finally, we show that bacteria gain function in biofilms and that they were able to degrade a toxic amine in MWFs, which the same bacteria were unable to do in planktonic form. Full article

The characterization of historical tailings bodies is crucial for optimizing environmental management and resource recovery efforts. This study investigated the Bielatal tailings dam (Altenberg, Germany), examining its internal structure, material distribution influenced by historical flushing technology, and the spatial distribution of valuable elements. To evaluate the tailings resource potential, drill core sampling was conducted at multiple points at a depth of 7 m. Subsequent analyses included geochemical characterization using sodium peroxide fusion, lithium borate fusion, X-ray fluorescence (XRF), and a scanning electron microscope with energy dispersive X-ray spectroscopy (SEM-EDX). Particle size distribution analysis via a laser particle size analyzer and wet sieving was conducted alongside milieu parameter (pH, Eh, EC) analysis. A theoretical assessment of the tailings’ potential for geopolymer applications was conducted by comparing them with other tailings used in geopolymer research and relevant European standards. The results indicated average concentrations of lithium (Li) of 0.1 wt%, primarily hosted in Li-mica phases, and concentrations of tin (Sn) of 0.12 wt%, predominantly occurring in cassiterite. Particle size analysis revealed that the tailings material is generally fine-grained, comprising approximately 60% silt, 32% fine sand, and 8% clay. These textural characteristics influenced the spatial distribution of elements, with Li and Sn enriched in fine-grained fractions predominantly concentrated in the dam’s central and western sections, while coarser material accumulated near injection points. Historical advancements in mineral processing, particularly flotation, had significantly influenced Sn distribution, with deeper layers showing higher Sn enrichment, except for the final operational years, which also exhibited elevated Sn concentrations. Due to the limitations of X-ray fluorescence (XRF) in detecting Li, a strong correlation between rubidium (Rb) and Li was established, allowing Li quantification via Rb measurements across varying particle sizes, redox conditions, and geological settings. This demonstrated that Rb can serve as a reliable proxy for Li quantification in diverse contexts. Geochemical and mineralogical analyses revealed a composition dominated by quartz, mica, topaz, and alkali feldspars. The weakly acidic to neutral conditions (pH 5.9–7.7) and reducing redox potential (Eh, 570 to 45 mV) of the tailings material indicated a minimal risk of acid mine drainage. Preliminary investigations into using Altenberg tailings as geopolymer materials suggested that their silicon-rich composition could serve as a substitute for coal fly ash in construction; however, pre-treatment would be needed to enhance reactivity. This study underscores the dual potential of tailings for element recovery and sustainable construction, emphasizing the importance of understanding historical processing techniques for informed resource utilization. Full article

Chert gravel, a byproduct of sand quarrying, remains an underutilized material in construction due to its low microwave (MW) absorption and high mechanical strength. The present study deals with the potential of MW irradiation as a novel, energy-efficient method for processing chert gravel into high-quality aggregates, reducing reliance on virgin materials. The research systematically examines MW exposure duration (1–2.5 min), rock size (150–800 g), moisture conditions, and cooling methods (air vs. water quenching) to optimize fragmentation. Experimental results indicate that larger rock sizes (600–800 g) yield coarser, less uniform aggregates, while prolonged MW exposure (>2 min) induces extensive micro-fracturing, producing finer, well-graded particles. Water quenching significantly intensifies fragmentation, generating irregular but highly fragmented aggregates, whereas pre-wetted samples exhibit finer and more uniform breakage than dry samples. The findings introduce a novel approach for optimizing chert gravel fragmentation, a material previously considered unsuitable for MW treatment. The study proposed a customizable methodology for tailoring aggregate properties through precise control of MW parameters, offering a sustainable alternative to conventional crushing. The results contribute to resource conservation, reduced energy consumption, and climate change mitigation, paving the way for more sustainable construction practices. Full article

The marketability of fresh granadilla (Passiflora edulis) fruit is significantly reduced by oxidation reactions occurring in its exocarp, which is not directly linked to the organoleptic quality of its arils. However, organic means of mitigating this are not topical in research. This study investigated the potency of moringa (Moringa oleifera)-based coating to preserve antioxidant compounds in granadilla. Physiologically mature fruit of equal size were assigned to a completely randomized design experiment at the North-West University Farm Laboratory. The fruit samples were coated with 2% xanthan gum (commercial coating), 2% moringa, or 2% rosemary coating and kept at shelf-life conditions (25 ± 2 °C; 40 ± 5%RH) for 5 weeks while sampling at weekly intervals. Correlations between the measured parameters were confirmed prior to regression analysis. Significant (p < 0.05) differences were observed in weekly changes in the exocarp pH, total antioxidant compounds (TAO), tartaric acid (TA), malic acid (MA), and citric acid (CA). At the end of storage, the moringa- and xanthan-coated fruit had the highest exocarp pH (7.8) and TAO (0.87 mg/g). Moringa-coated fruit had higher TA and MA (6.0 and 5.36 µg/g, respectively) as well as a significantly higher CA (0.51 µg/g) preserved than the other coatings. Strong correlations between MA and TAO (r > 0.82), as well as TA and TAO (r > 0.86), indicated the potency of developing TAO estimation models using multivariate data from the organic acids. Pre-processed data regression models were developed but were limited by the amount of data collected. Models developed similarly can be used for sustainable TAO assessment as a latent variable to minimize toxic waste that results from wet chemistry analyses. Full article

Granulation is a size enlargement process that involves the movement of feed within the granulator (e.g., drum) to produce granules of desirable attributes for the subsequent processes. To produce good quality granules, the right operating parameters need to be tested, optimised, and benchmarked for future granulation test works or potential scale-up for pilot test works. Thus, in this paper, the effects of feed residence time (FRT), pre-wetting moisture content (PWMC), mixing and granulation moisture content (GMC), drum volume loading (DVL), and rotational speed (DOS) on the granulation of iron ore sinter feed blends (SFBs) containing a high content of magnetite concentrate were studied by using a rotary drum granulator. The resultant granules were characterised by bed permeability, particle binding strength, bulk density, porosity, and size distribution. From the results, pre-wetting the SFB with 80% of the GMC for 2 min mixing of the feed generated better results. The batch-wise drum loading of 4 and 12% at a 15 rpm drum speed produced granules of optimum pre-ignition bed permeability, strength, and uniform size distribution. Although the higher drum speeds (e.g., 40 rpm) showed a higher pre-ignition bed permeability of about 54 JPU due to the production of coarse size granules, the granules were weak, hence showed a higher bed shrinkage of 2.2 mm. Additionally, granulation kinetics studies indicated 5–7 min of granulation to be the optimum residence time. It was established that the optimum granulation moisture content strongly depended on the nature of SFBs, more importantly, the mineralogy and particle size distribution. Granulation moisture content increased with increasing magnetite concentrate levels in the SFBs. These established optimum drum operating parameters could be applied for the granulation of SFBs containing higher levels of magnetite concentrate, as it is essential to operate the drum at the right operating conditions when there is a significant variation in feed mineralogy and particle size distribution. Full article

Exploiting novel crosslinking chemistry, this study pioneers the use of waterborne polyurethane (WPU) to chemically crosslink porcine-derived gelatin, producing enhanced gelatin hydrogel films through a solvent-casting method. Our innovative approach harnesses the reactive isocyanate groups of WPU, coupling them effectively with gelatin’s hydroxyl and primary amino groups to form robust urea and urethane linkages within the hydrogel matrix. This method not only preserves the intrinsic elasticity of polyurethane but also significantly augments the films’ tensile strength and strain. Comprehensive characterizations of these hydrogel films and pre-formed hydrogel reaction mixtures were conducted using viscosity measurements, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), and the universal testing machine (UTM) for tensile-recovery assessments, alongside evaluations of their biocompatibility. The results demonstrated a reduction in pore size with an increase in WPU concentration from 2 to 6% in the developed hydrogels with a decrease in the equilibrium swelling ratio from 15% to 9%, respectively. Further, hydrogels with 6% WPU exhibited the highest tensile stress in both a dry and wet state. The gelatin hydrogel formed with 6% WPU blend also demonstrated the growth and proliferation of CCD-986K (fibroblast) and CCD-1102 (keratinocyte) cells for up to 5 days of co-culturing. The results indicate a notable enhancement in the mechanical properties and biocompatibility of gelatin hydrogels upon the introduction of WPU, positioning these films as superior candidates for biomedical applications such as tissue engineering and wound dressing. Full article

Non-sintered lightweight aggregate (NSLA) produced by pelletizing and autoclaved curing has received widespread attention due to its environmental protection. However, the effect law of its characteristics, such as particle gradation and water absorption, on the performance of concrete still lacks clear understanding. In this study, seven different gradation types of concrete were designed to investigate the influence of the particle gradation (particularly particle size) of NSLA on the mechanical properties, especially the axial compressive performance, of alkali-activated slag non-sintered lightweight aggregate concrete (AN-LAC). Meanwhile, the different pre-treatment methods for NSLA were also studied to reduce the drying shrinkage of AN-LAC caused by the high water absorption of NSLA. The results showed that the compressive strength, splitting tensile strength, and flexural strength of AN-LAC at 3 d, 7 d, and 28 d showed an increasing trend when the average particle size decreased. The compressive strength of AN-LAC containing 3~5 and 6~10 mm NSLA at 28 days reached the maximum value of 56.7 MPa. AN-LAC containing NSLA with a small particle size exhibited improved elastic modulus. And the modified elastic modulus prediction model of AN-LAC was established considering the effect of particle size of NSLA. The NSLA, which was modified by using a silicone hydrophobic agent and pre-wetted by soaking in water, respectively, could enhance the strength of AN-LAC at 28 days. Combined with the analysis of the microscopic morphology of the ITZ, the shrinkage rate of the concrete with pre-wetted NSLA and modified NSLA at 90 days decreased by 17.7% and 10.3%, respectively. Full article

Known for their compact size, mobility, and off-road capabilities, motorcycles are increasingly used for logistics, emergency rescue, and reconnaissance. However, due to their two-wheeled nature, motorcycles are susceptible to instability, heightening the risk of tipping during cornering. This study includes some research and exploration into the following aspects: (1) The design of a front-wheel steering self-balancing controller. It achieves self-balance during motion by adjusting the front-wheel steering angle through manipulation of handlebar torque. (2) Trajectory tracking control based on preview control theory. It establishes a proportional relationship between lateral deviation and lean angle, as determined by path preview. The desired lean angle then serves as input for the self-balancing controller. (3) A pre-braking controller for enhanced active safety. To prevent lateral slide on wet and slippery surfaces, the controller is designed considering the motorcycle’s maximum braking deceleration. These advancements were validated via a joint BikeSim and Matlab/Simulink simulation, which included scenarios such as double lane changes and 60 m-radius turns. The results demonstrate that the intelligent motorcycle equipped with the proposed control algorithm tracks trajectories and maintains stability effectively. Full article

Previous studies have shown that over-wet soil is challenging to compact and exhibits large creep deformation. The consolidation test of small specimens cannot accurately reflect the compression law, and creep is underestimated owing to size effects, which affects the engineering quality. In order to accurately analyze the compression process of over-wet soil and establish its settlement calculation method, this study focuses on over-wet soil in Anhui Province, China, and uses a large-sized tester to load and analyze its compression law. The thermogravimetric analysis method was employed to investigate the changes in water with different binding forces during the compression process, and the settlement calculation method for over-wet soil was explored. The results show that the creep of over-wet soil is large and long-lasting, and the three-stage consolidation division method based on the $d-t$ curve is more effective in analyzing its regularity. The creep of over-wet soil is directly proportional to its water content. When the load exceeds the pre-consolidation pressure, the creep deformation becomes more significant, accounting for about 60% of the deformation under a single level load. It is recommended to use the creep coefficient ($\lambda$) for calculation. The results of the thermogravimetric analysis indicate that during the primary consolidation stage, free water is discharged, and weakly bound water is mainly discharged during the third consolidation stage, which is the main cause of creep. Finally, based on the relationship between the creep strain and water content of large samples, a calculation method for the settlement of over-wet soil foundations based on the layered summation method was established, which had a higher prediction accuracy than the conventional layered summation method. The results of this study will help clarify the deformation process and principle of over-wet soil and improve the quality of engineering. Full article

Embedding quantum dots into porous matrices is a very beneficial approach for generating hybrid nanostructures with unique properties. In this contribution we explore strategies to dope nanoporous SiO₂ thin films made by atomic layer deposition and selective wet chemical etching with precise control over pore size with CdSe quantum dots. Two distinct strategies were employed for quantum dot deposition: in situ growth of CdSe nanocrystals within the porous matrix via successive ionic layer adsorption reaction, and infiltration of pre-synthesized quantum dots. To address the impact of pore size, layers with 10 nm and 30 nm maximum pore diameter were used as the matrix. Our results show that though small pores are potentially accessible for the in situ approach, this strategy lacks controllability over the nanocrystal quality and size distribution. To dope layers with high-quality quantum dots with well-defined size distribution and optical properties, infiltration of preformed quantum dots is much more promising. It was observed that due to higher pore volume, 30 nm porous silica shows higher loading after treatment than the 10 nm porous silica matrix. This can be related to a better accessibility of the pores with higher pore size. The amount of infiltrated quantum dots can be influenced via drop-casting of additional solvents on a pre-drop-casted porous matrix as well as via varying the soaking time of a porous matrix in a quantum dot solution. Luminescent quantum dots deposited via this strategy keep their luminescent properties, and the resulting thin films with immobilized quantum dots are suited for integration into optoelectronic devices. Full article

Indirect evaporative coolers (IECs) for air conditioning rely on liquid water being sprayed into the exhaust stream of used air to induce evaporation and cool down the incoming stream of fresh air in an indirect heat exchanger. This paper describes a computational fluid dynamics analysis that makes use of the particle transport model to simulate the evaporation of the water droplets at the exhaust side of an IEC using a pre-implemented spray dryer model. Critical parameters include the average size of the droplets and the amount of water sprayed into the system. In addition to droplet evaporation, the evaporation of water from the wet wall on the exhaust side is accounted for. The results show the calculated temperature field in both air streams, the pressure distribution, the relative humidity distribution at the exhaust side and the particle tracks. The predicted wet bulb efficiency of around 30–35% is moderate but in agreement with the literature to date, and it can be attributed to the small heat exchanger size. A parametric study investigated the effect of the droplet size and mass flow rate. At an average size of 50 microns and below, the effect of the mass flow rate is quite strong, while at a higher droplet size the mass flow effect is small. Overall, the model can be used to shed fundamental understanding in order to increase the performance of the IEC while maintaining its compactness. Full article