Stirring Apparatus Research Articles

Cellulose hydrolysis reactor incorporating stirring apparatus for use with carbon-based solid acid catalyst

A highly efficient reactor with a stirring device was specially designed with the intent of performing the hydrolysis of pure crystalline cellulose using a carbon-based solid acid catalyst. This catalyst comprised an amorphous carbon-based material bearing –SO3H, –COOH and –OH groups. The stirring apparatus had seven blades coated with polytetrafluoroethylene and arranged axially at regular intervals with a 60° offset. This design proved highly effective, providing double the glucose yield compared with conventional stirring systems. The basic properties of this novel reactor were investigated and analyzed and are discussed herein.

Powder properties of carbon-based solid acid catalyst for designing cellulose hydrolysis reactor with stirring apparatus

The powder properties of a carbon-based solid acid catalyst, an amorphous carbon material bearing SO3H, COOH and OH groups, were investigated for the hydrolysis of cellulose. The Carr flowability and floodability indices, the angle of internal friction (adherence), and the particle size distribution and shape for the powder catalyst were determined. The need to develop a special reactor with a stirring apparatus for the hydrolysis of cellulose was determined based on the Carr flowability index. Insight into the interaction or adherence between the catalyst and crystalline cellulose during the hydrolysis process was gained by measuring the internal friction angle. The optimum moisture content in the catalyst to achieve the maximum adherence was investigated.

Study on dissolution behavior in vitro of an osteoporosis treatment drug: eldecalcitol soft capsule

Objective：To establish a method for the dissolutions profile determination of Eldecalcitol softgels, evaluate the in vitro dissolutions behavior between domestic Eldecalcitol soft capsules and the original preparation。Methods：The effects of different stirring apparatus, different dissolutions medium, different agitation speeds on the dissolutions behavior of Eldecalcitol soft capsules were investigated, cumulative dissolutions were calculated by measuring the dissolutions samples with HPLC-MS/MS method. Results：The dissolutions test of Eldecalcitol soft capsules was carried out by rotating basket method, agitation speed of 75 rpm, temperature of 37℃ in four mediums。Conclusion：This dissolutions method can be effectively applied to the dissolutions test of soft Eldecalcitol capsules. and the selected generics have good dissolution consistency with the original drugs. Keywords：Eldecalcitol soft capsules；dissolutions method；dissolutions behavior；consistency evaluation

ОСОБЕННОСТИ КОНСТРУИРОВАНИЯ, ПУТИ И ПРОБЛЕМЫ СОВЕРШЕНСТВОВАНИЯ АППАРАТОВ С ВИБРАЦИОННЫМ ПЕРЕМЕШИВАНИЕМ

In the article, the general description of components of vibratory stirring apparatus is given, using an apparatus of typical design as an example. Recommended standards for calculations and design are given for the main components. It is noted that in domestic practice, there is currently no unified methodology – that establishes an interrelation between the embodiment and the attained aim of the product – for designing of vibratory devices. In the materials of the work, based on the analysis of data from scattered sources, for the first time in the domestic literature, systematized summary information is provided on the parameters describing the design and operation mode of vibration stirring apparatus. In conclusion, the need is educed to develop integrated recommendations to implement and automate the approach to the design of modern, energy-efficient and promising equipment

Effectively enhancing recovery of fine spodumene via aggregation flotation

The effects of shear strength on aggregation flotation processes for fine spodumene (particle size less than 19 μm) were investigated in this study. Sodium oleate was used as a surfactant and collector. The shear strength was controlled by varying the agitation speed of a self-made stirring apparatus. The aggregation process was studied by measuring the continuous transformations in the size distribution and shape of flocs. The results showed that as the shear strength increased, the distribution of fine spodumene transformed from bimodal to unimodal mode. The flocs tended to bridge more branches with a high shear strength and form globule-like flocs with very high strengths. The parameter “aggregation degree” was introduced to evaluate the aggregation process as a function of shear strength. The flotation rate of flocs formed with different shear strengths was also studied. These results demonstrated that the flotation rate was closely related to shear strength and that there was a close correlation between this and aggregation degree. These results could be used to guide the actual production of fine particles via shear aggregation flotation. Aggregation process was divided into formation, growth, bridge, and breakage stage. A parameter named aggregation degree was proposed to elaborate floc growth under various shear conditions. Optimizing shear strength in aggregation stage further improved flotation efficiency.

Improved cellulosic ethanol production from corn stover with a low cellulase input using a β-glucosidase-producing yeast following a dry biorefining process.

A low-cost and sustainable cellulosic ethanol production is vital for fermentation-based industrial applications. Reducing the expenses of cellulose-deconstruction enzymes is one of the significant challenges to economic cellulose-to-ethanol conversion. Here, we report the improved ethanol production from corn stover after dry biorefining using a natural β-glucosidase-producing strain Clavispora NRRL Y-50464 with a low cellulase dose of 5mg protein/g glucan under separate enzymatic hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) conditions. Strain Clavispora NRRL Y-50464 exhibited a superior ethanol fermentation performance over Saccharomyces cerevisiae DQ1 under both conditions. It produced an ethanol titer of 38.1g/L within 96h at a conversion efficiency of 55.5% with 25% solids loading (w/w) via SSF without addition of extra β-glucosidase supplement. Improved performance of Y-50464 on a bioreactor with a helical stirring apparatus confirmed its advantage over the conventional bioreactors originally designed for liquid fermentations in cellulosic ethanol conversion by SSF. The results of this study suggested that the strain Clavispora NRRL Y-50464 has a potential as a candidate for lower-cost cellulosic ethanol production from lignocellulosic materials.

Efficiency of mixed-flow heat exchangers

It has been shown that studies are aimed at improving existing apparatuses and their elements in the agitating zone of liquids. A great deal of attention is devoted to investigating heat exchange upon stirring, the problem of the intensification of which has not been solved completely. For this reason, apparatuses with vertical heat-exchange units are considered to be promising. A model that allows for the assumption of the effect of the features of the design of agitator and heat-exchange units designed as vertical tubes on the heat-exchange efficiency in the stirring apparatus has been suggested. Results of experimental investigations of hydrodynamics and heat exchange in the apparatuses under study have been given and their high heat effectiveness has been demonstrated. The effectiveness of heat transfer has been compared in the blocks with parallel and series-connected tubes at identical flow rates of the heat carrier in the pipes of each block. No difference in the effectiveness of heat transfer is observed in the entire range of the rotation frequency of a stirrer. At higher water consumption, a block with parallel-connected pipes provides a higher amount of heat flow due to the larger driving force of heat transfer. Experimental data are generalized based on the theoretical dependence for calculating the coefficient of heat withdrawal from the agitated medium. The possibility of increasing coefficients of heat withdrawal from the agitated medium is only restricted by the supplied mechanical energy. An example of the calculation of apparatuses has been given.

Hydrogen Reduction of Hematite Ore Fines to Magnetite Ore Fines at Low Temperatures

Surplus coke oven gases (COGs) and low grade hematite ores are abundant in Shanxi, China. Our group proposes a new process that could simultaneously enrich CH4from COG and produce separated magnetite from low grade hematite. In this work, low-temperature hydrogen reduction of hematite ore fines was performed in a fixed-bed reactor with a stirring apparatus, and a laboratory Davis magnetic tube was used for the magnetic separation of the resulting magnetite ore fines. The properties of the raw hematite ore, reduced products, and magnetic concentrate were analyzed and characterized by a chemical analysis method, X-ray diffraction, optical microscopy, and scanning electron microscopy. The experimental results indicated that, at temperatures lower than 400°C, the rate of reduction of the hematite ore fines was controlled by the interfacial reaction on the core surface. However, at temperatures higher than 450°C, the reaction was controlled by product layer diffusion. With increasing reduction temperature, the average utilization of hydrogen initially increased and tended to a constant value thereafter. The conversion of Fe2O3in the hematite ore played an important role in the total iron recovery and grade of the concentrate. The grade of the concentrate decreased, whereas the total iron recovery increased with the increasing Fe2O3conversion.

The relevancy of controlled nanocrystallization on rifampicin characteristics and cytotoxicity.

PurposeThis article investigated the influence of novel rifampicin nanosuspension (RIF NS) for enhancing drug delivery properties.MethodsRIF NS was fabricated using the antisolvent precipitation technique. The impact of solvent type and flow rate, stabilizer type and concentration, and stirring time and apparatus together with the solvent–antisolvent volume ratio on its controlled nanocrystallization has been evaluated. NSs were characterized by transmission electron microscopy, particle size and zeta potential analysis, solubility, and dissolution profiles. The compatibility between RIF and the stabilizer was investigated via Fourier transform infrared spectroscopy and the differential scanning calorimetry techniques. The shelf-life stability of the RIF NS was assessed within a period of 3 months at different storage temperatures. Cell cytotoxicity was evaluated using 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on lung epithelial cells.ResultsPolyvinyl alcohol at 0.4% w/v, 1:15 methanol to deionized water volume ratio and 30-minutes sonication were the optimal parameters for RIF NS preparation. Nanocrystals were obtained with a nanometeric particle size (101 nm) and a negative zeta potential (−26 mV). NS exhibited a 50-fold enhancement in RIF solubility and 97% of RIF was dissolved after 10 minutes. The RIF NS was stable at 4±0.5°C with no significant change in particle size or zeta potential. The MTT cytotoxicity assay of RIF NS demonstrated a good safety profile and reduction in cell cytotoxicity with half maximal inhibitory concentration values of 0.5 and 0.8 mg/mL for free RIF and RIF NS, respectively.ConclusionA novel RIF NS could be followed as an approach for enhancing RIF physicochemical characteristics with a prominence of a safer and better drug delivery.

Experimental study of molten metal flow and numerical simulation of magnetic field during permanent magnet stirring and its application in continuous casting

Molten metal flow and magnetic field of the permanent magnet stirring (PMS) were investigated by experimental study and numerical simulation, respectively. A laboratory experiment was first performed to study the effects of PMS on the flow velocity of the Sn-20%Pb hypereutectic alloy during solidification. The results showed that the center magnetic flux density and stirring frequency were the two key factors affecting the electromagnetically-driven convection of the molten alloy. The electromagnetic field analysis software Opera-3D was used to develop a materials-saving and highly effective final permanent magnet stirring (FPMS) apparatus comprising a reasonable magnetic field design. Based on the scalar potential formulation, the stationary magnetic fields of the PMS were calculated and the number, arrangement and size of the permanent magnets were optimized. Thereafter, a pair of arc NdFeB permanent magnets with optimally designed geometrical dimensions was developed for industrial use in the FPMS apparatus. Consequently, with the industrial application of the new equipment in continuous casting, an improvement of the macrosegregation and other macro-defects of the rectangular billet were obtained.

Tribological Properities of Oil-Based ZnO Nanofluids

In this research, the friction and wear characteristics of nanofluids were studied through experimental investigation by dispersing ZnO nanoparticles into 60SN base oil. Oleic acid was used as a surfactant for the improved dispersibility and stability of nanofluids. Nanoparticles were dispersed using a magnetic stirring apparatus and ultrasonic bath. The micro/nano mechanics comprehensive test system UNMT- 1 wear testing machine was used to evaluate the friction properties. The wear track was measured by a Zeiss laser confocal microscope and scanning electron microscope (SEM). The effect of ZnO nanoparticles on the friction and wear performance of the nanofluids was investigated, and the optimal ratio between the surfactant and particle concentration was studied. The results showed that oil-based nanofluids with ZnO nanoparticles could reduce friction and wear under certain conditions. The optimally stable concentration of the fluids was that the oleic acid adding quantity was 5wt%～10wt% and ZnO nano-particles was 0.2wt%～0.7wt%. And when the oleic acid adding quantity was 10wt% and ZnO nanoparticles was 0.2 wt%, the nanofluids had best friction-reducing and anti-wear properties.

Ultrasound-assisted preparation of emulsion and its application in 1-naphthol wastewater treatment

A stable emulsion with NaOH as the inner phase, sorbitan monooleate (span80) as the surfactant, and kerosene, cyclohexane, n-heptane, methylbenzene or p-xylene as the organic membrane phase, was prepared successfully by a magnetic stirring apparatus at low stirring speed (720rev min−1) to make the pre-emulsion and then using the ultra-sonication devices. The separation efficiency in emulsion liquid membrane system to remove 1-naphthol was investigated. The parameters that affect the removal efficiency of 1-naphthol were studied systematically. At the optimal conditions, cyclohexane as the solvent phase, 2% NaOH as the inner phase, ultrasound time 5 minutes, the ratio of oil to inner phase 1:2, pH of feed phase without adjusted (pH = 6·4), contact time 15 minutes, ratio of emulsion to water 1:5, 1-naphthol removal can nearly reach 98% with a low level of 1·14% of emulsion leakage at 20 minutes.

Effect of ZrO2 particle on the performance of micro-arc oxidation coatings on Ti6Al4V

This paper investigates the effect of ZrO2 particle on the oxidation resistance and wear properties of coatings on a Ti6Al4V alloy generated using the micro-arc oxidation (MAO) technique. Different concentrations micron ZrO2 particles were added in phosphate electrolyte and dispersed by magnetic stirring apparatus. The composition of coating was characterized using X-ray diffraction and energy dispersive spectrum, and the morphology was examined using SEM. The high temperature oxidation resistance of the coating sample at 700°C was investigated. Sliding wear behaviour was tested by a wear tester. The results showed that the coating consisted of ZrTiO4, ZrO2, TiO2. With ZrO2 particle addition, the ceramic coating's forming time reduced by the current dynamic curve. It was shown that the addition of ZrO2 particles (3g/L, 6g/L) expressed an excellent oxidation resistance at 700°C and wear resistance.

Research on Properties of AROPOL G102 / Clay Nanocomposites

Unsaturated polyester resins are widely used in the manufacture of fiber reinforced plastics and shipbuilding industry. Their undesirable mechanical property may bring about disadvantages. The nanoparticles were added to the polymer material, which will strengthen the performance of the polymer material. AROPOL G102 / Clay Nanocomposites were prepared by magnetic stirring apparatus at room temperature. The result showed that nano-montmorillonite can effectively increase the mechanical property of the material.

Experimental Investigation of Polishing Character of Rotating Magnetic Polishing Fluids

In the face of the mechanical part of shape complex, the surface is difficult to be finished by the automatic and effective methods, but the magnetic fluid mixed with the polishing and cutting particles has motion characteristics in magnetic field. This paper introduces a kind of polishing technology which can rotate magnetic polishing fluid in the influence of magnetic field. The viscosity and hardness of magnetic polishing fluid change under the magnetic field, and the magnetic polishing fluid rotates in the fluence of the magnetic stirring apparatus, when machining magnetic in the liquid in polishing, and fixed in the liquid in proper position. When we select the best position in the magnetic polishing fluids and immerse the workpiece in the magnetic polishing fluids, the magnetic fluids rotate and move relatively to the workpiece. The friction between the magnetic fluid and the surface of workpiece has the finishing efficiency. The experiment is carried out to study the relation of the roughness and polishing and location on the home-made polishing laboratory platform in detail. The experimental results show that the rotating magnetic polishing liquid can be used for polishing the workpiece in super smooth processing, which is much better than polishing abrasive alone in reducing surface roughness. The study opens a new field for the application of the magnetic fluid. However, the direction of the field, the speed of the movement, and the polishing time of the process parameters still needs further research.

Improvement of Photoluminescence Uniformity of Porous Silicon by using Stirring Anodization Process

The electrolyte stirring method of anodization etch ing process for manufacturing porous silicon (PS) is re ported in this work. Two experimental setups of nature air stirring (PS- ASM) and electrolyte stirring (PS-ESM) are employed to clari fy the influence of stirring mechanisms on electrochemical etching proc ess. Compared to traditional fabrication without any stirring appara tus (PS-TM), a large plateau region of PS surface structure is obtained from samples with both stirring methods by the 3D-profiler measurement. Moreover, the light emission response is also improved by both pr oposed electrolyte stirring methods due to the cycling force in electr olyte could effectively enhance etch-carrier distribution while the electrochemical etching process is made. According to the analysis of statistical calculation of photoluminescence (PL) intensity, lo wer standard deviations are obtained from PS-samples with studied stirring methods, i.e. the uniformity of PL-intensity is effectively improved. The calculated deviations of PL-intensity are 93.2, 74. 5 and 64, respectively, for PS-TM, PS-ASM and PS-ESM.

Study of the Effect of Formulation Parameters/Variables to Control the Nanoencapsulation of Hydrophilic Drug via Double Emulsion Technique

Preparation of biodegradable nanoparticles containing active molecule is now taking much attention of researchers. The aim of the present work is to achieve the nanosize particles for the first time by double emulsion (W1/O/W2,) evaporation method to encapsulate hydrophilic substance using high performance stirring apparatus. A fluorescent stable hydrophilic agent (Stilbene derivative) was used as a model drug to be encapsulated. For this purpose, PCL (polycaprolactone) was chosen as polymer in this study. Several kinds of stabilizers [triton-405, tween 80, poloxamer, PVP (polyvinylpyrrolidone), PEG (poly ethylene glycol) & PVA (poly vinyl alcohol)] were investigated and the results indicate that the PVA (0.5% concentration) leads to the most stable double emulsion with the particle size in nano range. Different parameters affecting the size of particles have been studied such as stirring time (for 1st and 2nd emulsion), stirring speed (for 1st and 2nd emulsion), polymer and stabilizer concentrations etc. After duration of one month, the encapsulation efficiency of obtained particles was estimated using U.V. analysis. Transmission Electron Microscopy (TEM) showed that the prepared particles were spherical in shape. The size and size distribution were found to be submicron and ranging from 150 to 400 nm.

Design optimization and standardization of an environmental availability test under both acidic and alkaline conditions

The objective of this study was to design a procedure for an environmental availability test under both acidic and alkaline conditions for solid wastes and recycled materials and products. The procedure was designed on the basis of the Dutch availability test NEN 7371. Bottom ash from a municipal solid waste incinerator and copper slag were used as test materials. The influences of the type and intensity of liquid stirring apparatus and the open area ratio of the top of the leaching vessel were investigated experimentally, and partial least-squares modeling was applied as multivariate data analysis for the simultaneous evaluation of the three leaching conditions. Interlaboratory validation was then carried out with the participation of seven laboratories in accordance with JIS Z 8402-2/ISO 5725-2. Both repeatability and reproducibility were found to be acceptable, but precise calibration of the pH electrode is required. The proposed procedure will provide sufficient accuracy as a standard test method.

A novel knotted cotton-thread carrier: its potential use in achieving the biomass renewal of Phanerochaete chrysosporium in an immobilized growth system

In order to achieve an innovative strategy to renew the biomass of Phanerochaete chrysosporium in an immobilized growth system which can maintain white-rot fungi biomass, a novel knotted cotton-thread carrier was designed and made. By using a high-speed stirring apparatus under the conditions of 1400 r/min stirring speed for 6 min, mycelia immobilized on the knotted cotton-thread carriers were exfoliated completely and homogenized to a proper size. Furthermore, the homogenized mycelia from the immobilized mycelia can resume their growth on the knotted cotton-thread carriers in agitated flask cultures. The average regrowth biomass on the new carriers and the reused carriers was 0.0171 g/carrier and 0.0314 g/carrier, respectively. It proves that the knotted cotton-thread carrier performs perfectly in homogening the immobilized mycelia to achieve the biomass renewal of P. chrysosporium in an immobilized growth system.

Development of dissolution method for benznidazole tablets

The aim of this work was the development of a dissolution method for benznidazole (BNZ) tablets. Three different types of dissolution media, two stirring speeds and apparatus 2 (paddle) were used. The accomplishment of the drug dissolution profiles was compared through the dissolution efficiency. The assay was performed by spectrophotometry at 324 nm. The better conditions were: sodium chloride\hydrochloride acid buffer pH 1.2 with stirring speed of 75 rpm, volume of 900 mL and paddle as apparatus. Ahead of the results it can be concluded that the method developed consists in an efficient alternative for assays of dissolution for benznidazole tablets.