Numerical Analysis of Effects of Specularity Coefficient and Restitution Coefficient on the Hydrodynamics of Particles in a Rotating Drum

Various simulations have been conducted to understand the macroscopic behavior of particles in the solid-gas flow in rotating drums in the past. In these studies, the no-slip wall boundary condition and fixed restitution coefficient between particles were usually adopted. The paper presents a numerical study of the gas-solid flow in a rotating drum to understand the effect of the specularity coefficient and restitution coefficient on the hydrodynamic behavior of particles in the segregation process. The volume fraction, granular pressure, granular temperature and their relationships are examined in detail. The boundary conditions of the no-slip and specularity coefficient of 1 are compared. In the simulations, two different sizes of particles with the same density are considered and the Eulerian–Eulerian multiphase model and the kinetic theory of granular flow (KTGF) are used. The results reveal that the hydrodynamical behavior of the particles in the rotating drum is affected by the boundary condition and restitution coefficient. In particular, the increase of specularity coefficient can increase the active region depth, angle repose, granular pressure for both small and large particles and granular temperature for large particles. With increasing restitution coefficient, the angle of repose decreases and granular pressure and temperature increase at the same volume fraction for both small and large particles.

Microscopic Mechanism Angle of Repose in Friable Loess and Its Relationship With Slope Angle

The angle of repose in soil particles plays a key role in slope stability. There was a need for the investigation on the association between the angle of repose in loess particles and the angle of slopes. The fixed funnel methods with different particle sizes were carried out. The pressure of particle gravity weight was obtained based on the vibration stacking test. Four contact structures in loess particles were put forward including the triangular pyramid contact structure (TS), rectangular pyramid contact structure (RS), pentagonal pyramid contact structure (PS), and hexagon contact structure (HS). The particles transformed successively in four kinds of contact structures. The transformation of entropy value of the particles in different accumulation areas was discussed during the process of accumulation. The relationship between the natural angle of repose and the evolution of the contact structures was established. Combined with the existing experimental conclusion that loess particles transform in four stable states, in turn, the reason that the friction angle of uniform sand particles proposed by Shields in 1936 is 33° was explained. The formation theory of the loess angle of repose was well extended to speculate the formation process of the loess slope system. It is verified that loess slopes were mainly distributed under 30°.

FORMULATION OF EFFERVESCENT GRANULES FROM RED GINGER (ZINGIBERIS OFFICINALE ROSCOE VAR. RUBRUM) EXTRACT AND ITS ANTIOXIDANT ACTIVITY

Objective: Ginger is one of the Indonesian plants that has been used as traditional medicine. The flavonoids and phenols compounds contained high antioxidant activity. This study aimed to formulate effervescent granules (EG) from red ginger (RG) extract and evaluate its antioxidant activity. Methods: The formulation of EG from RG extract was prepared by the wet granulation method using different concentrations of polyvinylpyrrolidone (PVP). Furthermore, the flowability of granules was evaluated, including flow rate, angle of repose, bulk density, tapped density, Carr's index, Hausner ratio, and effervescent time. The physical stability of granules such as organoleptic evaluation, effervescent time, and pH measurement was also evaluated after 28 d of storage, and the antioxidant activity of EG from RG extract was determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH). Results: The result showed that the EG of RG extract was successfully prepared by wet granulation with a concentration of 15%. In addition, the flowability study showed that all formulas of EG from RG extract have good flow properties, and the granules showed excellent flow properties based on Carr′s index results. The effervescent time of granules remained within the acceptable range according to USP, and the physical stability did not change even after 28 d of storage. The IC50 of EG from RG extract was 283.28±3.6 ppm and has moderate in free radicals scavenging activity. Conclusion: EG from RG extract can be used as food supplements to protect the human body from free radicals and inhibit oxidases.

Experimental Study on the Mechanical Properties of Friction, Collision and Compression of Tiger Nut Tubers

The mechanical properties of agricultural materials can provide the basis for the design and optimisation of agricultural machinery. There are currently very few studies on the mechanical properties of tiger nut tubers, which is not conducive to the design and development of machinery for their harvesting and processing. To obtain the mechanical parameters of tiger nut tubers, this study investigated the effects of variety (Zhong Yousha 1 and Zhong Yousha 2), moisture content (8%, 16%, 24%, 32% and 40%), contact material (steel, aluminium, plexiglass and polyurethane), release height (170 mm, 220 mm, 270 mm and 320 mm), loading speed (5 mm/min, 10 mm/min, 15 mm/min and 20 mm/min), compression direction (vertical and horizontal) on the friction, collision and compression mechanical properties of the tubers. The results were as follows: Both moisture content and contact material had a significant effect (p < 0.01) on the sliding friction coefficient (0.405–0.652) of the tubers; both variety and moisture content had a significant effect (p < 0.01) on the angle of repose (27.96–36.09°); contact material, moisture content, release height and variety all had a significant effect (p < 0.01) on the collision recovery coefficient (0.376–0.672) of tubers; variety, loading speed, moisture content and compression direction all had significant effects (p < 0.01) on the damage force (87.54–214.48 N), deformation (1.25–6.12 mm) and damage energy (82.38–351.08 mJ) of the tubers; only moisture content and compression direction had significant effects (p < 0.01) on the apparent elastic modulus (12.17–120.88 MPa) of the tubers. The results of this study can provide a reference for the design and optimisation of machinery for the harvesting and processing of tiger nut tubers.

Numerical evidence of persisting surface roughness when deposition stops

Do evolving surfaces become flat or not with time evolving when material deposition stops? As one qualitative exploration of this interesting issue, modified stochastic models for persisting roughness have been proposed by Schwartz and Edwards (2004 Phys. Rev. E 70 061602). In this work, we perform numerical simulations on the modified versions of Edwards–Wilkinson (EW) and Kardar–Parisi–Zhang (KPZ) systems when the angle of repose is introduced. Our results show that the evolving surface always presents persisting roughness during the flattening process, and sand dune-like morphology could gradually appear, even when the angle of repose is very small. Nontrivial scaling properties and differences of evolving surfaces between the modified EW and KPZ systems are also discussed.

FORMULATION AND INVITRO EVALUATION OF SOLID DISPERSION TABLETS OF SILYMARIN

Objective: The research aims to formulate and evaluate Solid Dispersion tablets of Silymarin. Methods: Solid dispersions of Silymarin were prepared with various concentrations of carriers by using solvent evaporation method. The prepared solid dispersions were compressed into tablets by using 8 mm punch rotary tablet punching machine, with the hardness of 3.5kg /cm2.The formulated tablets were evaluated for various quality control parameters. Results: Silymarin was mixed with various proportions of excipients which showed no drug-excipients interactions. The precompression blend of Silymarin solid dispersions were characterized with respect to angle of repose, bulk density, tapped density, Carrs index and Hausners ratio. The precompression blend of all the batches indicated good to fair flowability and compressibility. Conclusion: The tablet passed all the tests. Among all the formulations F4 formulation containing, Drug and PEG 4000 in the ratio of 1:4 showed good result that is 94.95 % in 60 minutes. As the concentration of polymer increased the drug release was increased. While the formulations containing PEG 6000 showed less release. Hence from the dissolution data it was evident that F4 formulation is the better formulation.

Calibration and Tests for the Discrete Element Simulation Parameters of Fallen Jujube Fruit

Discrete element method (DEM) simulation is an important method to analyze the interaction relationship between materials and equipment, and to develop machinery and/or equipment. However, it is necessary to input specific simulation parameters when establishing a DEM simulation model. In this study, the interval values were measured through angle of repose tests of fallen jujube fruit (FJF), and the simulation angle of repose tests for FJF were established with EDEM software (DEM Solutions Ltd. Edinburgh, Scotland, UK). Then, the Plackett-Burman design, steepest ascent search experiment, and center composite design experimental methods were utilized to obtain the specific values of the simulation parameters from the interval values. The results showed that significant influencing factors in the simulation angle of repose include the Poisson’s ratio, the static friction coefficient between FJF, and the static friction coefficient between FJF and the steel plate, for which the optimal values were 0.248, 0.480, and 0.309, respectively. The angle of repose tests’ results showed that the error was 0.53% between the simulation angle of repose (29.69°) and the angle of repose (29.85°). In addition, the flow rate test results showed that the average error was 5.84% between the physical and simulation tests. This indicated that the calibrated parameters were accurate and reliable, and that the simulation model can accurately represent the physical tests. Consequently, this study provides an EDEM model of FJF that was essential in designing machinery and equipment through the EDEM simulation method.

FORMULASI TABLET HISAP EKSTRAK RIMPANG TEMULAWAK (Curcuma xanthorrhiza Roxb) DENGAN BAHAN PENGISI SORBITOL DAN LAKTOSA

Abstrak Temulawak adalah tanaman yang tumbuh berumpun, yang telah dimanfaatkan oleh sebagian masyarakat Indonesia, baik sebagai obat tradisional, sebagai pewarna maupun sebagai bahan pangan. Perlu dibuat sediaan tablet hisap agar dapat digunakan dengan nyaman dan praktis. Tujuan penelitian ini adalah untuk menguji pengaruh kombinasi bahan pengisi sorbitol dan laktosa terhadap karakteristik granul ekstrak rimpang temulawak dan terhadap mutu fifik tablet hisap ekstrak temulawak. Tablet hisap esktrak rimpang temulawak dibuat dengan campuran bahan pengisi sorbitol dan laktosa dengan konsentrasi berbeda yaitu F1 (sorbitol 5%: laktosa 95%), F2 (Sorbitol 10% dan laktosa 90%), F3 (Sorbitol 15%: Laktosa 85%), F4 (Sorbitol 20% : laktosa 80%), F5 (Sorbitol 25%: laktosa 75%). Tablet dibuat dengan granulasi basah. Penelitian ini menggunakan desain eksperimental laboratorium dengan melakukan pengamatan dan pencatatan hasil dari formulasi tablet hisap ekstrak rimpang temulawak (Curcuma xanthorrhiza Roxb) dengan bahan pengisi sorbitol dan laktosa. Data yang diperoleh dianalisis menggunakan SPSS versi 21 dengan metode ANOVA oneway dengan tingkat kepercayaan 95%. Hasil dari penelitian ini yaitu konsentrasi sorbitol dan laktosa terbaik untuk menghasilkan tablet hisap ekstrak temulawak adalah konsentrasi sorbitol (5%) dan laktosa (95%) dengan kecepatan alir 16,5±0,304 g/detik, persen kompresibilitas 6,57±0,069%, kadar lembab 1,47±0,06%, kekerasan 10,25±0,79 kP. Dari penelitian ini dapat disimpulkan bahwa penambahan konsentrasi sorbitol dapat menurunkan sifat tabletasi dan memperbaiki sifat fisik dari granul, makin tinggi konsentrasi sorbitol kekerasan tablet semakin menurun, dan meningkatkan kerapuhan dan waktu hancur tablet. Sedangkan semakin banyak konsentrasi laktosa meningkatkan sifat alir sudut diam, persen kompresibilitas dan menurunkan kadar lembab. Kata kunci : Temulawak, Tablet hisap, Sorbitol, Laktosa Abstrak Temulawak is a plant that grows in clumps, which has been used by some Indonesian people, both as traditional medicine, as a dye and as a food ingredient. It is necessary to make lozenges so that they can be used comfortably and practically. The purpose of this study was to examine the effect of the combination of sorbitol and lactose as fillers on the granule characteristics of the temulawak rhizome extract and on the physical quality of the lozenges of the temulawak extract. Temulawak rhizome extract lozenges were made with a mixture of sorbitol and lactose as fillers with different concentrations, namely F1 (sorbitol 5%: lactose 95%), F2 (Sorbitol 10% and lactose 90%), F3 (Sorbitol 15%: Lactose 85%), F4 (Sorbitol 20%: lactose 80%), F5 (Sorbitol 25%: lactose 75%). Tablets are prepared by wet granulation. This study used a laboratory experimental design by observing and recording the results of the formulation of lozenges of temulawak rhizome extract (Curcuma xanthorrhiza Roxb) with sorbitol and lactose as fillers. The data obtained were analyzed using SPSS version 21 with the one-way ANOVA method with a 95% confidence level. The results of this study are the best concentrations of sorbitol and lactose to produce lozenges of temulawak extract are concentrations of sorbitol (5%) and lactose (95%) with a flow rate of 16.5±0.304 g/second, percent compressibility 6.57±0.069%, moisture content 1.47±0.06%, hardness 10.25±0.79 kP. From this research, it can be concluded that the addition of sorbitol concentration can decrease the tableting properties and improve the physical properties of the granules, the higher the sorbitol concentration, the lower the tablet hardness, and increase the friability and disintegration time of the tablets. Meanwhile, the more lactose concentration increases the flow angle of repose, the percent compressibility and reduces the moisture content Keywords : Temulawak, Lozenges, Sorbitol, Lactose Keywords : Temulawak, Lozenges, Sorbitol, Lactose

Spreadability of Metal Powders for Laser-Powder Bed Fusion via Simple Image Processing Steps

This paper investigates the spreadability of the spherical CoCrWMo powder for laser- powder bed fusion (PBF-LB) by using image processing algorithms coded in MATLAB. Besides, it also aims to examine the spreadability dependence with the other characteristics such as powder size distribution, apparent density, angle of repose. Powder blends in four different particle size distributions are prepared, characterized, and spreadability tests are performed with the PBF-LB. The results demonstrate that an increase in fine particle ratio by volume (below 10 µm) enhances the agglomeration and decreases the flowability, causing poor spreadability. These irregularities on the spread layers are quantified with simple illumination invariant analysis. A clear relation between powder spreadability and 3D printed structures properties in terms of residual porosity could not be defined since structural defects in 3D printed parts also depends on other processing parameters such as spatter formation or powder size over layer height ratio.

FORMULATION AND DEVELOPMENT OF SUSTAINED RELEASED GLICLAZIDE TABLETS WITH THE DIFFERENT HYDROPHILIC POLYMER BY USING DIRECT COMPRESSION

To effectively manage the diabetic mellitus type-II hyperglycemic problem, Gliclazide tablet is the sustained- release tablet that has been designed and fabricated for years. This research evaluated the effects of different grades of hydrophilic polymers in sustained release of Gliclazide tablets made with direct compression technique. HPC GF GRADE, HPMC K4M, and PARTECK® SRP 80 were used as the polymer, Avicel pH 101 (MCC) was used as the highly compressible diluent and Starch 1500 was used as insoluble tablet filler. Aerosil 300 and Magnesium Stearate was used as a Glidant and lubricant for improving the flow property of powder and to decrease the friction between dying wall and punches. Pre-compression characteristics were evaluated for angle of repose, bulk density, compressibility, tapped density, and Hausner's ratio and DSC, XRD, FT-IR. Tablets were prepared on a rotary tablet press machine (Eliza press) and after compression tablets were evaluated for weight variation, thickness, hardness, friability, drug content, and in-vitro drug release study. The physico-chemical properties of blends were estimated accelerated stability study was also developed formulations were kept for stability study for three months as per ICH guidelines and found to be stable. Advantages of formulating insoluble drugs such as Gliclazide is that if it is used in the preparation of capsules or tablets of the drug,its dose might be reduced which is economically beneficial.