Search Results (2,375)

Chlortetracycline hydrochloride (CTC) is a broad-spectrum tetracycline antibiotic with a wide range of antibacterial activities. Due to low solubility, poor stability, and low bioavailability, clinical preparation development is limited. We sought to improve these solubility and dissolution rates by preparing solid dispersions. A hydrophilic polymer was selected as the carrier, and a solid dispersion was prepared using a medium grinding method, with samples characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), and particle size distribution (PSD). To maximize CTC solubility and stability, different polymer types and optimal drug-to-polymer ratios were screened. The solubility of optimized povidone K30 (PVPK30) (1/0.75, w/w)-, hydroxypropyl-β-cyclodextrin (HP-β-CD) (1/2, w/w)-, and gelatin (1/1, w/w)-based solid dispersions was 6.25-, 7.7-, and 3.75-fold higher than that of pure CTC powder, respectively. Additionally, in vitro dissolution studies showed that the gelatin-based solid dispersion had a higher initial dissolution rate. SEM and PS analyses confirmed that this dispersion had smaller and more uniform particles than PVPK30 and HP-β-CD dispersions. Therefore, successful solid polymer dispersion preparations improved the CTC solubility, dissolution rates, and stability, which may have potential as drug delivery systems. Full article

The liner is a wear-prone component in ball mills, subject to continuous impacts, squeezing, and abrasion from the grinding media during operation. Its service performance directly affects the working efficiency of the ball mill. The service life of mining ball mill liners is about 8 months, and frequent downtimes occur due to liner wear and loss of effectiveness, with liner replacement accounting for about 6% of the total cost, resulting in huge economic losses. This paper focuses on a Φ305 mm × 150 mm experimental ball mill, using the discrete element software Rocky Discrete Element Method (DEM) (software version number Rocky 2022 R2) for simulation modeling analysis. With Φ10 mm and Φ20 mm mono-size particle simulations serving as reference groups, this study investigates the motion states and liner abrasion patterns under different liner heights for both sizes of grinding media in Equilibrium Quality Manufacturer (EQM) and Original Equipment Manufacturer (OEM) gradations. The results indicate that the impact of liner height on the wear of the ball mill liners is related to the size and gradation of the grinding media. The degree of liner wear from highest to lowest is as follows: EQM > Φ20 mm > OEM > Φ10 mm. Due to the effect of the cylinder end cap, the wear at the axial center of the ball mill liner is more severe than at both ends, and the wear on the facing side of the liner is more severe than on the backside. A thorough study of the influence of ball mill grinding media gradation on the wear pattern of liners is of great theoretical significance for optimizing liner structures, improving grinding efficiency, and promoting energy saving and cost reduction in ball mills. This study provides theoretical guidance for understanding the mechanisms behind liner wear in ball mills and predicting the liner lifespan. Full article

This study aimed to utilize the hydration characteristics of cement through wet grinding techniques to efficiently and conveniently prepare a stable C-S-H seed suspension, providing key parameters and a scientific basis for their large-scale production, which ensures the stability of the C-S-H suspension during production, transportation, and application. This preparation aimed to mitigate the adverse effects of high-volume silica fume on the early mechanical properties of high-performance cement concrete. The properties of C-S-H seed were characterized in detail by SEM, XRD, and TD. In the concrete performance test, silica fume was used to replace part of the cement, and different contents of C-S-H seed were added to test its effect on the compressive strength of concrete, with XRD and SEM used to analyze the performance differences. The results show that the particle size and hydration degree of cement no longer developed after 90 min of wet grinding. Polycarboxylate ether (PCE) superplasticizer can increase the fluidity of the crystal C-S-H seed suspension when the content exceeds 1.5%. When the content of PCE exceeded 2%, the C-S-H seed suspension precipitated. Adding 5% C-S-H seed can increase the compressive strength of cement concrete by 10% under the condition of reducing the amount of cement and increasing the amount of silica fume. And Ca(OH)₂ (CH) was produced by cement hydration consumed by silica fumes to generate C-S-H gel, by which the concrete became denser with more strength. However, when the amount of C-S-H seed exceeded 7%, the compressive strength of the concrete decreased. Full article

Helical grinding is crucial for manufacturing small holes in hard-to-machine composite ceramics. This study introduces a geometric model of undeformed chips to analyze the cutting characteristics of abrasive grains on both the bottom and side edges of the tool. It reveals for the first time that the distribution of cutting grains—pure bottom-edge, pure side-edge, and mixed-edge—is influenced by the tool diameter and eccentricity. A novel calculation method for the distribution range (D_p) of pure bottom-edge grains is proposed, demonstrating that using a tool diameter at or below two-thirds of the target hole diameter effectively eliminates pure bottom-edge grains, improving chip evacuation, reducing chip adhesion, and optimizing cutting performance. Experimental validation on small holes in SiC_p/Al composites (65% volume fraction) confirmed these findings and provides practical guidance for optimizing cutting parameters and tool design. Full article

Hard–brittle materials are widely used in the optics, electronics, and aviation industries, but their high hardness and brittleness make it challenging for traditional processing methods to achieve high efficiency and superior surface quality. This study aims to investigate the application of ultrasonic local resonant grinding to sapphire to improve the efficiency and meet the requirements for the optical window in the surface roughness of the material. The resonant frequency of a piezoelectric ultrasonic vibration system and the vibration amplitude of a grinding head’s working face were simulated and tested, respectively. The results of ultrasonic grinding experiments showed that the local resonant system reduced the surface roughness parameter (Ra) of sapphire to 14 nm and improved its surface flatness to 44.2 nm, thus meeting the requirements for the ultra-precision grinding of sapphire. Compared with a conventional resonant system, the surface roughness of the sapphire ground with the local resonant system was reduced by 90.79%, its surface flatness was improved by 81.58%, and the material removal rate was increased by 31.35%. These experimental results showed that ultrasonic local resonant grinding has better effects than those of conventional ultrasonic grinding in improving surface quality and increasing the material removal rate. Full article

6-thioguanine (6-TG) is an antimetabolite drug of purine structure, approved by the FDA for the treatment of acute myeloid lesukemia, and it is of interest in treating other diseases. The interaction of drugs with matrices is of interest to achieving a delayed, sustained, and local release. The interaction of 6-TG with an aluminum metal–organic framework (Al-MOF) DUT-4 is studied using a novel experimental approach, namely, mechano-chemistry by liquid-assisted grinding (LAG). The bonding of 6-TG to the DUT-4 matrix in the composite (6-TG)(DUT-4) was studied using ATR-FTIR spectroscopy and XRD. This interaction involves amino groups and C and N atoms of the heterocyclic ring of 6-TG, as well as the carboxylate COO⁻ and (Al)O-H groups of the matrix, indicating the formation of the complex. Next, an in vitro delayed release of 6-TG was studied from composite powder versus pure 6-TG in phosphate buffered saline (PBS) at 37 °C. Herein, an automated drug dissolution apparatus with an autosampler was utilized, and the molar concentration of the released 6-TG was determined using an HPLC–UV analysis. Pure 6-TG shows a quick (<300 min) dissolution, while the composite gives the dissolution of non-bonded 6-TG, followed by a significantly (factor 6) slower release of the bonded drug. Each step of the release follows the kinetic pseudo-first-order rate law with distinct rate constants. Then, a pharmaceutical shaped body was prepared from the composite, and it yields a significantly delayed release of 6-TG for up to 10 days; a sustained release is observed with the 6-TG concentration being within the therapeutically relevant window. Finally, the composite shows a time-dependent (up to 9 days) stronger inhibition of leukemia MV-4-11 cell colonies than 6-TG. Full article

Background/Objectives: Supported by a comparative study between conventional, grinding, and microwave techniques, a mild and versatile method based on the [1 + 3] cycloaddition of 2-((3-nitrophenyl)diazenyl)malononitrile to tether pyrazole and pyrimidine derivatives in good yields was used. Methods: The newly synthesized compounds were analyzed with IR, ¹³C NMR, ¹H NMR, mass, and elemental analysis methods. The products show interesting precursors for their antiproliferative anti-breast cancer activity. Results: Pyrimidine-containing scaffold compounds 9 and 10 were the most active, achieving IC₅₀ = 26.07 and 4.72 µM against the breast cancer MCF-7 cell line, and 10.64 and 7.64 µM against breast cancer MDA-MB231-tested cell lines, respectively. Also, compounds 9 and 10 showed a remarkable inhibitory activity against the Hsp90 protein with IC₅₀ values of 2.44 and 7.30 µM, respectively, in comparison to the reference novobiocin (IC₅₀ = 1.14 µM). Moreover, there were possible apoptosis and cell cycle arrest in the G1 phase for both tested compounds (supported by CD1, caspase-3,8, BAX, and Bcl-2 studies). Also, the binding interactions of compound 9 were confirmed through molecular docking, and simulation studies displayed a complete overlay into the Hsp90 protein pocket. Conclusions: Compounds 9 and 10 may have apoptotic antiproliferative action as Hsp90 inhibitors. Full article

Animal bones, particularly from cattle after slaughter, are commonly discarded, posing environmental challenges and highlighting the need for sustainable valorization. This study investigated the effect of enzyme and organic acid treatment on physicochemical properties, particle size, microstructure and safety of meat-bone paste (MBP). Two samples were prepared: a control (MBP-C) without enzyme treatment and an experimental sample (MBP-E) treated with pepsin and ascorbic acid. Results showed that the enzyme reaction rate increased from 0.004 mmol/min at 60 min to 0.014 mmol/min at 120–180 min before declining to 0.006 mmol/min at 480 min, suggesting substrate depletion or product inhibition. Temperature greatly influenced reaction rates, peaking at 0.0129 mmol/min at 30 °C, with significant declines at higher temperatures due to enzyme denaturation. The enzyme’s kinetic performance was proportional to the pepsin concentration, demonstrating enhanced catalytic efficiency at higher enzyme concentrations. Particle size analysis revealed that enzyme treatment significantly reduced bone particle size, with 86.33% of particles measuring between 0.05 and 0.2 mm, compared to 86.4% between 0.25 and 0.75 mm in the untreated sample. Microscopy confirmed these findings, showing an average particle size reduction from 0.21 mm to 0.052 mm after enzyme treatment. Physicochemical analysis revealed no significant differences in chemical composition between the two samples. However, enzyme-treated MBP-E exhibited a lower pH (5.9) compared to MBP-C (7.02), attributed to the addition of ascorbic acid. Water-binding capacity significantly increased in MBP-E (82.54% vs. 77.28%), indicating enhanced hydration and collagen loosening during enzymatic action. Enzyme treatment significantly reduced the total viable count and eliminated pathogenic bacteria (E. coli, Listeria, Salmonella), improving MBP safety. These findings highlight the potential of this approach for valorizing animal bones as a valuable food ingredient while promoting sustainable waste management practices. Full article

Energy savings and consumption reduction of ball mills are crucial for industrial production. The grinding medium is an important component of a ball mill. In theory, using higher-density grinding media can yield better grinding results. However, for materials with varying grindability, employing grinding media of different densities can reduce energy consumption while maintaining the same grinding effect. This study simulates the motion of the grinding media in the mill using three different densities of balls and the same material (iron ore). The results reveal that balls with densities of 5.8 g/cm³ and 7.8 g/cm³ achieve faster grinding of materials into finer particles, but balls with a density of 5.8 g/cm³ consume less energy. Therefore, replacing a ball with a density of 5.8 g/cm³ in a ball mill can significantly reduce energy consumption. This study will assist in selecting the optimal grinding medium density for different materials, ultimately contributing to energy savings and reduced carbon emissions. Full article

Nickel is an important raw metal material in industry, which has been identified as a strategic mineral resource by the Chinese Ministry of Land and Resources. Nickel sulfide ore accounts for 40% of all nickel ores worldwide. However, magnesium silicate gangue minerals in sulfide nickel ores, particularly serpentine, pose significant challenges to the flotation of nickel sulfide ores. The presence of magnesium silicate gangue leads to a series of issues, including increased energy consumption in subsequent smelting processes, accelerated equipment wastage, and increased SO₂ emissions, which severely impact the comprehensive utilization of nickel resources in sulfide nickel ores. In this regard, flotation depressants are the most direct and effective method to reduce adverse influences caused by magnesium silicate gangue in the flotation of nickel sulfide ore concentrate. Based on the characteristics of the typical magnesium-containing nickel sulfide ore, this review illustrates the difficulties of the depression of magnesium silicate gangue during the flotation of nickel sulfide ore and gives an overview of the common depressants from six aspects (chelation depressants, dispersion depressants, flocculation depressants, depressants for grinding, depressants for slurry adjustment and combination depressants). Each section summarizes the relevant depression mechanisms and analyzes the advantages and disadvantages of various reagents, providing a reference for designing depressants specifically targeting serpentine. Full article

This study evaluated the changes in physicochemical properties and appearance quality of long-grain rice during the grinding process using image technologies and aimed to provide reference for future research. The brown rice milling process was divided into three stages, and flatbed scanning, scanning electron microscopy (SEM), X-ray micro-computed tomography (micro-CT), low-field nuclear magic resonance (LF-NMR), and headspace–gas chromatography–ion mobility spectrometry (HS–GC–IMS) were employed to examine the physicochemical and volatile properties of the samples. Results revealed a continuous increase in the degree of milling, with a broken rice rate and a whiteness value increasing by 50.84% and 21.13%, respectively, compared with those during the initial stage; dietary fiber and vitamin B1 contents were reduced by 54.41% and 66.67%, respectively. The image results visualized showed that the cortex of brown rice was gradually peeled off with the increase in milling degree; the cortical thickness was gradually reduced, the endosperm was gradually exposed, and the surface was smoother and shinier. T₂ populations exhibited a shift toward longer relaxation times, followed by a decrease in relaxation time during the milling process. Additionally, 31 target compounds impacting rice flavor, mainly ketones, alcohols, and esters, were identified, and the concentration of volatile substances in the B region decreased with the reduction in the bran layer; the concentration of volatile substances in the C region provided rice flavor, which increased with the milling process. This study showed changes in the physicochemical properties and appearance quality of long-grain brown rice during milling. Furthermore, the use of various image processing techniques offers significant insights for optimizing processing parameters and enhancing overall quality and taste. Full article

Coffee flavor is profoundly influenced by numerous factors, including the origin’s terroir and variety, as well as post-harvest processing, drying, and sorting. Even specialty coffee beans, carefully selected for their high quality, can exhibit a wide range of flavor profiles depending on how they are roasted and ground. Traditionally, the coffee industry has used the Brewing Control Chart, which considers total dissolved solids (TDS) and extraction (E), to guide professionals toward achieving consistent flavors. However, this chart has limitations in representing the complex chemical composition and its influence on the sensory attributes of coffee. This study explores a more comprehensive approach to evaluating coffee quality by utilizing a taste sensing system (electronic tongue) to measure acidity and bitterness for full-immersion brewing. We investigate the impact of brew ratio and grind size on these taste attributes, while also considering the influence of roast level. Our findings demonstrate that finer grind sizes significantly affect TDS and E, while roast level and grind size significantly affect sensory attributes, as measured by the taste sensing system. This approach complements the traditional Brewing Control Chart by providing a more nuanced understanding of how roast level and grind size influence coffee flavor. Full article

Three novel Zn(II) mononuclear complexes with the general formula ZnL₂Cl₂ (L = 2-(4-R-phenylmethylene)benzimidazol-2-hydrazines; R-H (1), R-CH₃ (2), and R-OCH₃ (3)) were synthesized and fully characterized by various means. These complexes demonstrate excitation-dependent emission, which is detected by a change in the emission color (from blue to green) upon an increase in the excitation wavelength. Moreover complex 1 shows reversible mechanochromic luminescence behavior due to the reversible loss of solvated methanol molecules upon the intense grinding of crystals. In addition, 1 exhibits vapochromic properties, which originate from the adsorption methanol vapor on the crystal surface. The strengthening of anthelmintic activity at the transition from free hydrazones to zinc-based complexes is shown. Full article

This research investigates the mechanical activation of kaolin as a supplementary cementitious material at the laboratory scale, aiming to optimize milling parameters using the response surface methodology. The study evaluated the effects of rotation speed and milling time on the amorphous phase content, the reduction in crystalline kaolinite, and impurity incorporation into the activated clay through the Rietveld method. The results demonstrated that adjusting milling parameters effectively enhanced clay activation, which is crucial for its use in low-carbon cements. High rotation speeds (300/350 rpm) and prolonged grinding times (90/120 min) in a planetary ball mill increased the pozzolanic activity by boosting the formation of amorphous phases from kaolinite and illite and reducing the particle size. However, the results evidenced that intermediate milling parameters are sufficient for reaching substantial degrees of amorphization and pozzolanic activity, avoiding the need for intensive grinding. Exceedingly aggressive milling introduced impurities like ZrO₂ from the milling equipment wear, underscoring the need for a balanced approach to optimizing reactivity while minimizing impurities, energy consumption, and equipment wear. Achieving this balance is essential for efficient mechanical activation, ensuring the prepared clay’s suitability as supplementary cementitious materials without excessive costs or compromised equipment integrity. Full article

Hydrogen permeation resistance in the welded region of 06Cr18Ni11Ti steel is relatively weak due to surface defects, which need high integrity surface machining. The parameters of the welding material for 06Cr18Ni11Ti steel are currently unavailable, which causes some inconvenience for simulation studies. To fill the lack of 06Cr18Ni11Ti steel weld material parameters in the relevant literature at the present stage, the quasi-static tensile test at different strain rates and notch specimen tensile tests were conducted in this paper and determined the Johnson–Cook (J-C) constitutive model parameters and Johnson–Cook failure model parameters. Subsequently, a multi-grain grinding simulation model was built based on W-M fractal dimension theory by using the determined material parameters. The influence of processing parameters on grinding heat was analyzed. Grinding experiments were conducted to analyze the influence of processing parameters on grinding heat and grinding force. By comparing the simulation and experimental results, it is revealed that the average error is 9.37%, indicating relatively small discrepancy. It is demonstrated that the grinding simulation model built in this paper could efficiently simulate the grinding process, and the determined weld material parameters of 06Cr18Ni11Ti steel have been verified to possess high accuracy and reliability. Full article