Milled Samples Research Articles

Could the small molecules such as amino acids improve aqueous solubility and stabilize amorphous systems containing Griseofulvin?

Griseofulvin (GSF) is an antifungal drug that has low aqueous solubility and low oral bioavailability. Amorphous systems are capable to promote rapid drug dissolution, usually affording concentrations above drug solubility in the gastrointestinal tract (supersaturation) in order to promote better absorption. Thus, the aim of this work was to evaluate the ability of amino acids, as hydrophilic carriers, to improve drug kinetic solubilization and to stabilize GSF supersaturated solutions, as well as to stabilize GSF amorphous systems at solid-state. The effect of 5 amino acids on GSF precipitation behavior was investigated by solvent shift method. Amorphous systems were developed by ball milling (GSF + amino acid 1:1 M ratio) and Quench Cooling (to obtain GSF QC) techniques. The samples were characterized by solid-state techniques, submitted to in vitro kinetic solubility studies and evaluated under stability tests. Aspartic acid, methionine, valine and tryptophan demonstrated similar anti-precipitant abilities in phosphate buffer pH 6.5. However, in FaSSIF biorelevant medium, tryptophan was only one able to slow down the drug precipitation. The characterization of milled samples showed that an amorphous system was obtained just using the combination of the drug with tryptophan (GSF-TRYP BM). At the higher dose tested (0.850 mmol L−1) during in vitro kinetic solubility studies, this amorphous system increased the AUC in FaSSGF (88.6%) and FaSSIF (58.2%) media when compared to GSF QC. Thus, the ability of this amino acid to inhibit GSF precipitation appears to be dependent on its concentration in solution and could be optimized. During the stability study, TRYP inhibited GSF recrystallization in the solid-state for a period of 12 months, whereas GSF QC recrystallized in 1 week.

Influence of high-energy ball milling on structural, microstructural, and optical properties of Mg2TiO4 nanoparticles

In this paper, we report the impact of mechanical activation on structural, microstructural, thermal, and optical properties of Mg2TiO4 (MTO) nanoparticles prepared by high-energy ball milling. Williamson–Hall (W–H) method was carried out in order to understand the origin of the broadening in the X-ray diffraction (XRD) peaks and for the estimation of crystallite size of MTO nanocrystalline powder. It is revealed that the peak broadening is not only due to reduced coherently diffracting domain size but also due to a significant strain distribution. The calculated strain was 9.0 × 10−3 and the average crystallite sizes are 40–60 nm for 35-h milled powder and this result is consistent with transmission electron microscopy (TEM) analysis. To examine the nature of lattice fringes for the 35-h milled samples, high-resolution TEM study was carried out. It revealed that the as-prepared samples are highly crystalline in nature. The surface morphological studies were carried out by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Further, MTO nanoparticles showed a strong absorption at ~ 356 nm, and the bandgap values ranged between 3.26 and 3.78 eV with an increase of milling time from 0 to 35 h. The photoluminescence (PL) spectrum measured at room temperature showed the bands which are belong to the near band edge emission at 357 nm. The MTO nanoparticles prepared by mechanical alloying method exhibited promising optical properties which are suitable for commercial optoelectronic applications.

The surface modification of aluminum by mechanical milling of Pb coating and high current pulsed electron beam irradiation

This paper reports the surface morphology and properties of Al substrates with Pb coating, which was deposited by mechanical milling and then treated by high current pulsed electron beam (HCPEB) irradiation. After HCPEB irradiation treatment, some previously formed defects such as micro-pits, craters, and bulged nodules were eliminated, resulting in significant reduction of surface roughness of initial Pb/Al sample, and the formation of a dense and adherent Pb/Al alloying layer. Notably, when the number of irradiation pulses reached 30, there was uniform distributions of Pb in the mixture of Pb and Al elements in the milled samples, which resulted in the formation of gray layers with thickness of 12 μm (milling for 1 h) and 8 μm (milling for 2 h). These formed layers effectively improved the wear resistance. Moreover, the hardness of Pb/Al sample also improved after HCPEB irradiation due to structure defect strengthening and ultra-fine Pb-rich particles reinforcement. The above results demonstrate that HCPEB treatment is an effective method to obtain high-quality alloy coating layer, resulting in the formation of an excellent alloy.

Differences in physicochemical properties of commercial rice from urban markets in West Africa.

Rice consumers in West Africa (WA) have an acquired preference for imported rice. Enhancing consumption of local rice requires matching the grain quality attributes of the imported benchmarks in addition to increasing productivity of local rice cultivars. Thus, there is a need to develop screening tools that will aid breeding programs select for high-yielding and stress-tolerant cultivars whose grain quality are at par with imported rice. Hence, this study evaluated various grain quality characteristics of 316 commercial milled rice samples from urban markets in three WA countries (Benin, Cameroon, and Ghana) and developed linear discriminant models (LDAs) to classify rice according to their origins and to predict the imported rice classification of local germplasm based on their grain quality attributes. More than half of the commercial rice samples that were collected originated from Thailand (60%); in contrast, only a small fraction was locally grown (2%). The commercial rice from different origins were distinguishable based on the quality attributes evaluated, contributing to the relatively high classification rates achieved by the fitted LDAs. These results indicate that multivariate models could be useful during varietal improvement as tools for screening for cultivars that can match the quality of imported rice.

Influence of the milling conditions on the thermal decomposition of Bayer gibbsite

A synthetic gibbsite (Al(OH)3) produced by the Bayer process was mechanically activated by attrition milling for 24 h with various grinding ball-to-powder ratios (BPR = 5, 10 and 20). Changes in its structure were studied by thermal analysis and X-ray diffraction. As a result of increasing ball-to-powder ratio, the grain size of gibbsite decreased while its specific surface area increased. Only for these materials, the formation of nanocrystalline boehmite (AlO·OH) and amorphous aluminium hydroxides was also observed. Upon having been heat treated between 200 and 1200 °C (2 h), boehmite was detected at the temperature range of 200 and 350 °C for the BPR10 sample, while the boehmite of BPR20 was transformed to γ- Al2O3 at 500 °C. Further, only α-Al2O3 was detected at 1200 °C for all samples. Finally, combining the TG-DSC, XRD and SEM results, it was proposed a mechanism for the thermal decomposition of the non-milled and milled samples.

Effect of solid state ball milling on wear and structural properties of polytetrafluoroethylene/alumina nanocomposite coatings

The aim of this study was to investigate the effect of ball milling at different time periods on wear resistance and structural changes of polytetrafluoroethylene (PTFE)/nano-alumina coatings. For this purpose, PTFE/nano-alumina composite powders containing 10 wt% of the nanofillers were milled at 0, 8, 16, and 20 h and coated on a steel substrate using powder electrostatic technique, followed by sintering. Wear mass loss and coefficient of friction (COF) of the coatings were evaluated by a pin-on-disk tribometer. The morphology and structural properties of the unmilled and milled powders and the coatings were explored using scanning electron microscopy (SEM) and X-ray diffraction analysis. In addition, the chemical structure of the samples was tested using Fourier-transform infrared spectroscopy. The results showed that the wear rate of the 16 h milled sample showed tenfold decrease compared to the neat PTFE. However, the COF of the milled samples did not change significantly after milling. Also, less damage was observed for the worn surface of the 16 h milled sample which confirmed the obtained values for the wear rates. Therefore, the ball milling process was effective in enhancing the wear resistance of the coatings.

Impact of Amorphization Methods on the Physicochemical Properties of Amorphous Lactulose.

The influence of the amorphization technique on the physicochemical properties of amorphous lactulose was investigated. Four different amorphization techniques were used: quenching of the melt, milling, spray-drying, and freeze-drying, and amorphous samples were analyzed by differential scanning calorimetry, NMR spectroscopy, and powder X-ray diffraction analysis. Special attention was paid to the tautomeric composition and to the glass transition of amorphized materials. It was found that the tautomeric composition of the starting physical state (crystal, liquid, or solution) is preserved during the amorphization process and has a strong repercussion on the glass transition of the material. The correlation between these two properties as well as the plasticizing effect of the different tautomers was clarified by molecular dynamics simulations.

Room temperature ferromagnetism in ball milled Cu-doped ZnO nanocrystallines: an experimental and first-principles DFT studies

Experimental and theoretical studies on the room temperature ferromagnetism of ball milled Zn0.95Cu0.05O nanocrystalline, were reported. X-ray diffraction analysis reveals that the most dominant crystalline phase is hexagonal wurtzite with presence of weak peaks due to Cu and CuO. Rietveld analysis indicated that the crystallite size decreases with increasing milling time, while the strain enhanced with milling time. Magnetic measurements using SQUID expose remarkable room temperature ferromagnetic ordering for milled samples. The physical origin of the ferromagnetism order has been explained using a bound magnetic polaron model. Theoretical calculations based on First principles methods were employed to calculate the electronic structures and magnetic properties of Cu doping and zinc and oxygen vacancies behavior of Zn1−xCuxO. It was found that a Cu dopant leads to induce magnetism and exhibits an increasing of magnetic moment when Zn vacancy are introduced.

Lithium recovery from mechanically activated mixtures of lepidolite and sodium sulfate

ABSTRACT Mixtures of lepidolite ore and sodium sulfate (Na2SO4) at mass ratios of 1:0.5 and 1:1 were prepared and milled using zirconia media in a planetary ball mill for 5 h. The 5 h milled samples were heated in a furnace at temperatures of 700°C or 800°C for one h under an air atmosphere. XRD results showed the formation of new phases such as LiKSO4, LiNaSO4 and Li2NaK(SO4)2 in the calcine. Unmilled samples showed no such reactions. The presence of well crystalline Li2NaK(SO4)2 phase in the calcine after heating at 700 indicated that chemical reactions between the lepidolite and Na2SO4 occur at lower temperatures after 5 h milling. Hot water leaching of the calcines showed that phases such as LiKSO4, LiNaSO4 and Li2NaK(SO4)2 were responsible for the increase in solubility of lithium. Increasing the calcination temperature had a more significant effect on the lithium dissolution than increasing the fraction of Na2SO4.

Combined use of a near-infrared spectrometer and a visible light grain segregator for accurate non-destructive determination of amylose content in rice

Amylose content contributes to the texture and the eating quality of rice. Industrial non-destructive measurement of the amylose content in rice using a near-infrared (NIR) spectrometer remains inaccurate. In this study, we analyzed whether using an NIR spectrometer along with a visible light (VIS) grain segregator improved the accuracy of conventional model for non-destructive determination of rice amylose content. NIR spectra collected from the NIR spectrometer and physical properties were collected from the VIS grain segregator from 603 milled samples of 10 varieties of rice produced between 2010 and 2016 in various regions of Hokkaido, Japan. Data were analyzed by partial least squares regression (PLS) and multiple linear regression (MLR) to develop a dual-step model. Our dual-step model was validated using production year samples (2016) that were different from the calibration set (2010–2015). Our method improved accuracy compared to the conventional method developed using data from an NIR spectrometer, with a standard error of prediction (SEP) = 0.94% and ratio of performance deviation (RPD) = 2.46. Our dual-step model also had the highest robustness when increasing the production year samples of the calibration set, enabling a more precise, accurate, and efficient rice quality screening in Japanese industry.

Dry and Wet Ball Mill Syntheses of Sb2Se3 from Its Constituent Elements

Binary antimony selenide (Sb2Se3) compound was synthesized by the mechanical alloying of constituent elements. Both dry and wet mill syntheses methods were applied. Dry milling was done in Ar atmosphere. Wet milling was done using toluene and n-butyl alcohol as a process control agent (PCA). It was found that Sb2Se3 phase was formed using toluene as PCA, whereas usage of n-butyl alcohol led to the formation of mixed phases consisting of Sb2Se3 and unreacted antimony and selenium. Single phase Sb2Se3 was obtained in 6 h and 13 h, respectively, through dry and wet milling, which was confirmed by x-ray diffraction (XRD) and Raman spectroscopy studies. Diffused reflectance spectroscopy studies of as-milled Sb2Se3 yielded direct band gap values of 1.10 eV and 1.18 eV for dry and wet milled samples, respectively. Particle-induced x-ray emission studies revealed that there is no impurity present in the compound and confirmed near stoichiometry. High-resolution transmission electron microscopy observations showed d spacing values of 0.28 nm for dry and toluene milled samples that corresponds to the (221) plane. The milled Sb2Se3 was used as source material and thin films were grown using the e-beam evaporation method. The as-grown films were characterized using XRD, Raman spectroscopy that showed a single phase nature of the films and optical transmission spectra analysis yielding a band gap of 1.29 eV. Electrical resistivity of the films was measured using a two probe method showing a resistivity of 1.6 × 107 Ω cm. Hot point probe measurement indicated that the as-grown Sb2Se3 films are p-type in nature.

FeGa2O4 nanowires preparation after milling and annealing of Fe doped GaN samples

In this work, FeGa2O4 nanowires were prepared using high-energy ball milling and subsequent annealing from GaN samples doped with Fe. The structural and chemical characterization were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC-TGA), and transmission electron microscopy (TEM). The XRD patterns showed that GaN samples doped with Fe reach nanocrystalline sizes after the process of high-energy ball milling. The DSC-TGA studies confirmed the GaN thermal decomposition and weight loss of the milled samples. XRD patterns reveal the formation of the FeGa2O4 compound with an fcc crystal lattice in GaN: Fe milled and subsequently annealed at 1100 °C. The TEM analysis of annealed powders showed the formation of FeGa2O4 nanowires with diameters of around 50 to 60 nm and lengths up to 2 μm. High-resolution transmission electron microscopy (HRTEM) images provide additional evidence of the fcc lattice structure of the nanowires. The decomposition of GaN produced FeGa2O4 nanowires since molten Ga at high temperature is combined with the doping element of Fe and then with the O2 in the air.

Effect of Milling Speed and Time on Ultrafine ZnO Powder by High Energy Ball Milling Technique

The particle size of commercial zinc oxide (ZnO) powder has been found in micron scale. For the improvement of ZnO properties, size reduction in nanoscale is required. In this work, the particle size of ultrafine ZnO powder was reduced by high energy ball milling technique. commercial grade ZnO powder with average size 0.8 μm was used as starting material. Milling speed and time of high energy milling process are considered as crucial parameters affecting size reduction of ZnO particles. Crystalline structure, surface morphological and particle size of the milled samples were investigated by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and particle analyzer, respectively. The results suggested that ZnO patterns after milling process with various milling speed and time were identically in hexagonal crystalline phase affirmed by XRD result. SEM images indicate that size of ZnO products distinctly decrease according to the increase of milling time and speed. ZnO particle size after milling process was found in ultrafine power in range of 200-400 nm. These results suggest that particle size of the commercial ZnO powders can be effectively minimized to few hundred nanometer range depending on force attraction and suitable rotation during milling process with specific speed and time. Moreover, the significant milling parameters will be studied to find the optimum condition for the production of ZnO particles in nanoscale.

Characterization of industrial aluminum trihydrate-filled poly(methyl methacrylate) composite powder

Aluminum trihydrate-filled poly(methyl methacrylate) (PMMA/ATH) is composite waste powder generated during the production of PMMA/ATH solid-surface composite sheets. It is estimated that 85,500 tons of this waste is being produced every year on a global scale. Since the information about it is scarce, this paper examines the physical characteristics of PMMA/ATH powder and the influence of milling upon its surface characteristics in order to determine its recycling and adhesion potentials. Non-milled powder particles show more irregular shape with more porous structure in comparison to milled powder. Milling causes the breaking of ATH particles in the PMMA matrix which leads to average particle size reduction and increased surface free energy. IGC results show higher values for than results derived by contact angle measurement. Nevertheless, the difference in values between non-milled and milled samples is even more obvious in IGC measurements than in contact angle measurements. The DSC curve of PMMA/ATH powder shows a typical thermal decomposition of aluminum hydroxides up to about 320 °C when an exothermic reaction is observed up to 445 °C, which is attributed to the burning of PMMA.

Impact of high energy ball milling on densification behaviour of magnesium aluminate spinel evaluated by master sintering curve and constant rate of heating approach

The present study investigates the influences of high energy ball-milling on densification of a commercial sub-micron magnesium aluminate spinel powder. High energy milling decreases the crystallite size and modifies the particle size distribution of powder resulting in better compaction of green bodies. Milling, also, increases the number of structural defects.The concept of master sintering curve (MSC) and the constant rate of heating (CRH) approach were employed to evaluate the activation energy of sintering. It was demonstrated that, according to MSC, the milled samples exhibit lower densification activation energy compared to the as-received powder (530 kJ mol−1 vs 750 kJ mol−1). Analysing the densification using CRH approach reveals that the sintering activation energy of milled samples remains constant during the sintering process, while that of as-received samples increases with densification. The estimated activation energy using MSC method is thus an average value of the values measured over the whole process of sintering.

Effect of advanced milling on carbothermal reduction of pyrolusite (MnO2) by carbonized tea plant waste

This study examined the effect of advanced milling on carbothermal reduction of oxidized manganese ore using carbonized tea plant waste as reductant.For the carbothermal reduction of manganese oxide, the ratios of Mn/Fe, C/(MnO2+Fe3O4) and ball/mixture were 8/1, 2/1 and 10/1, respectively. Samples were subjected to advanced milling in an attritor mill for 10, 15, 20, 30, 60, 90 and 120 h. The rotation speed of the mill shaft was 350 rpm during the processes performed in the attritor. DTA-TG, SEM and XRD analyses were carried out to characterize the samples. When XRD peaks were compared for different grinding times, it was seen that all of the diffraction peaks gradually decreased in parallel with the increase in grinding time. The DTA-TG analysis of the samples subjected to mechanical activation for 120 h shows a symmetrical change, which is similar to the Gaussian function. The activated samples obtained from advanced milling were treated at 1000, 1100, 1200 and 1300 °C for 30, 60, 90 and 120 min in an argon atmosphere. The results of the experimental studies indicate that a 58.76% reduction occurred in the 120 h advanced milled samples subjected to treatment at 1300 °C for 2 h.

Phase-structural and morphological features, dehydrogenation/re-hydrogenation performance and hydrolysis of nanocomposites prepared by ball milling of MgH2 with germanium

Ball milling of magnesium hydride with germanium additives in argon for up to 10 h was shown to result in the formation of nanocomposites of α- and γ-modifications of MgH2 together with individual Ge phase. When the as milled samples are heated-up, Ge interacts with MgH2 to form Mg2Ge at T = 350–400 °C; the phase transformation overlaps with MgH2 decomposition and Mg2Ge phase remains in the material after its re-hydrogenation at T = 300 °C and P(H2)∼15 bar.The ball milled Ge-MgH2 nanocomposites were found to be characterised by an improved hydrogen release via hydrolysis in organic acid solutions as compared to pure MgH2 prepared and tested at the same conditions. It was found that the composite containing 5 wt% of Ge and ball milled for 5 h showed the best hydrogen generation performance, with total hydrogen release exceeding 1.55 NL/g (yield close to 100%) in one minute.

Magnetocaloric Effect of Micro- and Nanoparticles of Gd5Si4

Materials exhibiting a large magnetocaloric effect (MCE) at or near room temperature are critical for solid-state refrigeration applications. The MCE is described by a change in entropy (ΔSM) and/or temperature (ΔTad) of a material in response to a change in applied magnetic field. Ball milled materials generally exhibit smaller ΔSM values compared to bulk; however, milling broadens the effect, potentially increasing the relative cooling power (RCP). The as-cast Gd5Si4 is an attractive option due to its magnetic transition at 340 K and associated MCE. Investigation of effect of particles size and transition temperature in the binary material, Gd5Si4, can lead to development of functionally graded bulk material with higher MCE and RCP than the traditional bulk materials. A two-step ball-milling process, in which coarse powder of Gd5Si4 was first milled with poly(ethylene glycol) followed by milling in heptane was used to produce fine particles of Gd5Si4 that showed a broad distribution in particle size. Magnetic measurement on the milled sample obtained after washing with water show a decrease in Curie temperature and significant broadening of the magnetic transition. Compared to bulk Gd5Si4, the maximum MCE of the milled samples is also reduced and shifted down by close to 30 K, but the MCE remains substantial over a broader temperature range. The RCP of both milled samples increased 75% from the bulk material.

Investigate the effects of synthesizing techniques on the particle size reduction and thermal behaviors of carbon-based material from natural wood charcoal

In this research work, a novel investigation of the carbon-based material from natural wood charcoal synthesized with various top-down techniques on the particle size reduction and thermal behaviors. First, three powder samples were synthesized using manually by hand. Second, two powder samples were synthesized using ball milling. The particle size (length and width) were analysed using SEM micrographs. Furthermore, the thermal characterization had been carried out using thermogravimetric analysis. The results showed that the length and width of the ball milled sample are smaller than the manually milled samples (53, 74 and 105 μm) due to the higher energy mill between the ball mill and the charcoal powder. The thermogravimetric analysis showed that the samples takes places in four steps of decomposition. First stage occurred at 49.9-50°C, second at 72.58-83.69 °C, third at 268-319 °C and fourth at 689-738 °C. The ball milled samples exhibited the lower weight loss total (23.3 and 59.12%) than the manually milled samples (29.58, 34.9 and 36.39%) which is affected by the chemical composition (lignin, cellulose and hemicellulose) and inorganic substances present in the samples. As a conclusion, the ball milling gave the optimum results in terms of particle size reduction and thermal behaviors.

Effects of various radio frequency treatment protocols on physicochemical properties and sensory quality of packaged milled rice

Many studies have shown that non-chemical radio frequency (RF) disinfestation method can maintain the original quality of grains. But there is a lack on developing effective RF treatment protocols based on physical and sensory quality of commercially packaged milled rice for industrial applications. A pilot-scale, 27.12 MHz, 6 kW RF system was used to study the physicochemical properties and eating quality of packaged milled rice under three sample weights (2.5, 5, and 10 kg) and treatment protocols (6, 11, and 26 min exposures to 54, 52 and 50 °C, respectively). The results showed that the same bottom area packaging was feasible based on the cooling time and the suitable electrode gaps of 9, 10 and 14 cm were chosen to develop the RF treatment protocol for 2.5, 5, and 10 kg samples, respectively. Although some influence on moisture content, water activity and amylose content, the RF treatment had no significant effect on fat, fatty acid, protein content, color, fissure ratio, and broken rate for packaged milled rice samples, and the overall score of the cooked rice. This study provides valuable information about the physicochemical properties and sensory quality of packaged milled rice under different RF treatment protocols.