Ultrasonic Stirrer Research Articles

INVESTIGATION OF SHIELDING PARAMETERS TO FABRICATED SHIELDS FROM POLYMER WITH NANO-BARIUM OXIDE MATERIALS

Researchers have long been involved in improving new and effective radiation-protection materials. In this study, we will verify the measurement of the attenuation coefficient of gamma rays, which is considered one of the most important points of protection from ionizing radiation, by fabricating a radiation-protective shield made by combining pol unsaturated polyester as a base material for the shield and reinforced by varying concentrations of the nano- barium oxide (BaO) in different proportions (15,25,35 and 45) %. Making use of an ultrasonic stirrer, and the radiation shielding properties of gamma rays are presented for the energies shown in this article. The results reveal that nanostructured samples are preferable at the linear and mass attenuation coefficients (LAC and MAC), the value of the shield's electronic density(Ne), and the value of radiation protection effectiveness (PRE) increased with the increase of reference material, which are considered good materials in radiation protection, but decreased with the increase in gamma ray energy. Keywords: BAO, LAC, MAC, NE, PRE

The effect of sedimentation phenomenon of the additives silver nano particles on water pool boiling heat transfer coefficient: A comprehensive experimental study

Nowadays, the increase in the number of nanoparticles in base fluids is considered as one of the most significant causes of change in thermodynamic properties and boiling heat transfer coefficient. Hence, the present study aims to examine the effects of different concentrations of silver nanoparticles on pool boiling inside deionized water. Five different nanoparticle concentrations were tested, namely (0.2, 0.4, 0.6, 0.8, 1) gr/lit. The nanoparticles were synthesized using the two-step method in an aqueous base fluid. A magnetic stirrer was first used to suspend the nanoparticles, and then the stabilization was performed using an ultrasonic stirrer. The average diameter of the nanoparticles is approximately 20 nm, and the stability results indicate that the nanofluids are highly stable. The stability results from the DLS test show that changing the pH of the base fluid by 9 at a concentration of 0.4 gr/lit results in stability of −40 mV. The boiling results of the deionized water were recorded in three steps and were compared to the Rohsenow curve. The variations were very similar to the Rohsenow curve, and the change in the wall superheat and the shifting of the curve can be due to the different conditions of the experimental apparatus. The results indicate that adding silver nanoparticles leads to a decrease in the boiling heat transfer coefficient provided that the roughness parameter is smaller than or equal to unity. Increasing the concentration can reduce the deviation in the boiling heat transfer coefficient at low heat fluxes and increase it at high heat fluxes. Furthermore, boiling heat transfer on sedimentation surfaces was examined in three sedimentation steps. The results show that an increase in sedimentation and a decrease in the roughness parameter cause a reduction in the boiling heat transfer coefficient.

Improving the impact resistance of the multilayer composites using nanoparticles

The application of composites in various industries has grown considerably. The relatively high cost of Low-Velocity Impact (LVI) tests and the limitation in data collection due to the short time of this test, on one hand, and previous reports of the conformity of Quasi-Static Indentation (QSI) test results to LVI test results, on the other hand, have convinced researchers to use QSI instead of LVI. The present research investigates the effect of various percentages of nanoclay (because of their cost-effectiveness) on the impact properties of glass-epoxy composite and has used the QSI test to predict the behavior of this nano-composite. For the homogeneous distribution of nanoclay in the resin, a mechanical and an ultrasonic stirrer were used, and the EDAX image of the nano-resin cross-section confirms the success of this process. The QSI test results showed that adding 3% nanoclay to the glass-epoxy composite improves energy absorption by 18%. Moreover, the SEM images indicated that the samples containing 7% nanoclay had deteriorated mechanical properties due to nanoparticle agglomeration. In the end, experimental and numerical LVI tests were performed on the samples containing zero and 3% nanoclay to evaluate the agreement between QSI and LVI test results. The increase in the maximum force and elastic energy and the decrease in the damping ratio and residual deflection all indicate the positive effect of clay nanoparticles on impact-resistance. Numerical results were also very well matched with experimental ones.

A bio-based epoxy resin from rosin powder with improved mechanical performance

Today, with the increasing sensitivity to environmental issues, bio-based materials are needed as an alternative to traditional materials. Rosin is used for biomaterial production due to its abundance in nature and cheapness. This study aims to produce bio-epoxy using powdered rosin with enhanced mechanical properties. Powdered rosin was used at 1, 3 and 5 wt.% to study the effect of additive ratios. Three different mixing methods were used to make the mixture homogeneous. A magnetic stirrer was used in the first method, an ultrasonic stirrer was used in the second method and both were used in the third method. Bio-epoxy was successfully synthesized, and mechanical properties were examined by tensile, compression, density and hardness tests. As a result, it was determined that the best mixing method was the third mixing method, and the best results in additive ratios were obtained at 1 wt.% for tensile strength (5.63%) and hardness (14.41%) and at 5 wt.% for compression strength (8.28%).

Tourmaline Nanoparticles Doped Polyvinylidene Fluoride (PVDF) Nanofibers

The aim of this work is to produce tourmaline (TM) doped polyvinylidene fluoride (PVDF) nano-composite fibers. TM-containing PVDF nanofibers were produced via a horizontally located electrospinning unit. N,N-dimethylformamide (DMF) and acetone were used as solvents. The amount of PVDF or PVDF/TM in the polymer solution was 20 wt.%. PVDF was dissolved in DMF in presence of heat by using a magnetic stirrer while TM powder was dispersed in Acetone in absence of heat by using an ultrasonic stirrer. These two solutions were then mixed for TM/PVDF nanocomposite fiber production. Pristine PVDF nanofibers were also electrospun as control samples. Produced nano-surfaces were analyzed under scanning electron microscopy (SEM), Fourier-transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD). Voltage generation capacities were investigated by recording the voltage outputs of samples under an applied rotational impact. The peak voltage produced by the TM doped PVDF nanocomposite fibers was higher than the PVDF nanofibers.

Effect of carbon nanotube reinforcement on the natural frequencies and damping ratios of nanocomposite beams

In this study, the effect of carbon nanotube (CNT) reinforcement on the natural frequencies and damping ratios of nanocomposite beams are examined. Three nanocomposite plates reinforced with different CNT weight ratios (0% neat epoxy-glass fiber composite beam, 0.25%, 0.5%) are produced. Multi Walled Carbon Nanotubes (Purity>96%, outside diameter < 8nm) are mixed into the epoxy resin with an ultrasonic stirrer. The plates also contain glass fibres as an additional reinforcement. Test specimens are cut parallel and perpendicular to the direction of the fibres to obtain two different sets of specimens. Free vibration tests are performed by a wireless accelerometer sensor (WAS), a wireless data acquisition system (WDA) and a PC. Natural frequencies and damping ratios are determined from the acceleration data obtained from the experiments. For both the 0° and 90° specimens an increase in natural frequency is observed. However, while the damping ratio of the 0° specimen increases, the damping ratio of 90° one decreases.

Effect of h-BN solid nanolubricant on the performance of R134a–polyolester oil-based vapour compression refrigeration system

The interest in the use of hexagonal boron nitride (h-BN) nanoparticles as solid nanolubricant for R134a–polyolester oil-based vapour compression refrigeration system was arisen because of its self-lubricating property, thermal and chemical stability. The present investigation analyzes the consequence of different volume concentrations of h-BN solid nanolubricant in the polyolester oil-based lubricant, on its density, viscosity and tribological aspects, as well as on the coefficient of performance of a vapour compression refrigeration system using R134a (1,1,1,2-tetrafluoroethane) refrigerant as the working fluid. Different samples of nanolubricants were prepared based on the volume percentage of h-BN nanoparticles using magnetic stir, low-intensity ultrasonic bath and high-intensity ultrasonic stirrer method. The tribological test results reveal that there is a momentous enhancement in antifriction behaviour in the nanolubricant compared to base polyolester oil. The nanolubricant containing 3 vol% h-BN nanoparticles shows a sixty percentage improvement in the energy saving as compared to base POE oil system.

Effects of dispersed added Graphene Oxide-Silicon Carbide nanoparticles to present a statistical formulation for the mixture thermal properties

This study experimentally investigated the preparation method, stability, measurement, and modeling of the thermal conductivity of water/graphene oxide-silicon carbide nanofluid. In this study, the nanofluid was prepared via a two-stage method. Moreover, the SEM and XRD tests were used to investigate surface and atomic structure of nanoparticles. A probe-type ultrasonic stirrer was used to achieve stability and homogenized distribution of particles in the base fluid. Then, the nanofluid stability was assessed using the DLS test. According to the results, the base fluid contained nano-sized particles. Moreover, the thermal conductivity measurement of the hybrid nanofluid was carried out in the temperature and volume concentration ranges of 25–50 °C and 0.05–1 vol%, respectively. The experimental variables were the nanofluid’s temperature and volume concentration. Results showed that the thermal conductivity of the nanofluid increased with increasing volume concentration and temperature. Although nanoparticle concentration has a greater impact than temperature, changes in thermal conductivity are greater at higher temperatures. The greatest increase in thermal conductivity of nanofluid was 33.2% at the concentration of 1 vol% and temperature of 50 °C. To calculate thermal conductivity of this nanofluid, a highly accurate experimental equation was developed using the laboratory data curve fitting method.

Influence of extraction method on antioxidant properties of Rheum ribes root extract

Abstract Rheum species are important medicinal herbs, often used in pharmacological research, due to the presence of anthracene derivatives in the subterranean parts of the plant. In this study, we intended to assess its antioxidant capacity, in correlation with the method of extraction. For this purpose, Rheum ribes extraction was realized with four solvents of different polarities (50% methanol, 70% ethanol, 80% acetonitrile, and petroleum ether). We used different extraction techniques, such as orbital shaker, ultrasonic stirrer, microwave, and Soxhlet extraction, and the total phenolic content of the Rheum ribes extracts was determined by modified Folin–Ciocalteu method. The reducing power and radical scavenging activity of the extracts were also evaluated. The results shown that the antioxidant activity of the extracts depends on the extraction methods especially through the used solvent and decreases in the order: ethanol &gt; methanol &gt; acetonitrile &gt; petroleum ether.

SYNTHESIS, CHARACTERIZATION AND ELECTROCHEMICAL PERFORMANCE OF ACTIVATED CARBON SUPPORTED MnO2 FOR ELECTROCHEMICAL CAPACITOR

MnO2 was synthesized by adding activated carbon into KMnO4 solution and stirred in a magnetic or ultrasonic stirrer. The obtained MnAC samples were characterized by means of XRD, TGA, TPR-H2, SEM and BET. All samples are amorphous and have porous structure. MnAC-M prepared by magnetic stirring have higher manganese content, earlier reduction temperature, smoother surface area while MnAC-U prepared by ultrasonic stirring have larger specific surface area and pore volume.

Investigation of the influence of ultrasonic stirring on mass transfer in the through-mask electrochemical micromachining process

Surface texturing is a widely accepted approach for friction reduction between mechanical components. Through-mask electrochemical micromachining is a simple and reliable process for metal surface texturing in which mass transport conditions have profound influence on final machined quality. An ultrasonic stirrer is usually adopted for mass transfer enhancement. However, understanding of the effects of ultrasonic stirring on mass transfer is limited, and is far from sufficient for developing guidelines for its practical application. In this work, the influences of ultrasonic stirring parameters on mass transfer have been investigated numerically and experimentally. With the numerical method, periodic pressure change in the electrolyte over time has been obtained, showing that ultrasonic stirring results in drastic transient pressure change in electrolyte fluid fields. Parameters related to ultrasonic frequency, vibration amplitude, and the depth of anode surface immersed in the electrolyte solution influence pressure amplitude. Validation experiments have been conducted and etched surface profile and morphology characterized, which show that the experimental observations are in agreement with numerical predictions. With the optimized mass transfer, well-defined micro-pits array of 30 μm and a smooth etched surface on tin-bronze substrate in large scale have been demonstrated.

Preparation and investigation of sodium alginate nanocapsules by different microemulsification devices

ABSTRACTNumerous techniques of preparation have been reported for the encapsulation of the core material, but the microemulsion technique is the most effective and commonly used for encapsulation. In this article, three microemulsification devices including ultrasonic stirrer, labo ratory reactor, and mechanical stirrer were used to produce the alginate nanocapsules containing peppermint oil. The effect of different parameters on surface morphology, mean particle size, and size distributions were investigated. The results indicated that the ultrasonic stirrer is the best device to make the nanocapsules containing essential oils prepared by microemulsion method, so that the size of nanocapsules prepared by ultrasonic stirrer was about 56 nm. Also, the results of GC‐MS, FTIR, and TGA show that quantities of the remaining compounds in nanocapsules prepared by ultrasonic stirrer are higher than other devices. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41904.

Effect of nanoclay addition on mechanical and thermal behavior of vinyl ester based nanocomposites obtained by casting

This paper presents the experimental study of mechanical and thermal properties of organically modified montmorillonite clay (Nanoclay) (0, 1, 2, 3, 4 and 5 wt.%) in the vinyl ester matrix by ultrasonic stirrer. The changes in mechanical properties are investigated by using tensile and impact testing machine. It was found that the addition of nanoclay particles significantly improved tensile properties of pure vinyl ester, but impact properties of pure vinyl ester were affected negatively with the nanoclay content in the nanocomposite. It was found that the absorbed energy and impact resistance of the nanocomposites decreased with increasing the nanoclay content. DSC curves showed the glass transition temperature change in the nanoclay reinforced vinyl ester nanocomposites as compared to the pure vinyl ester. XRD analysis was performed to identify the structure of nanocomposites. SEM results showed the change in fracture surface morphology of nanoclay reinforced vinyl ester nanocomposite. Also, homogeneous distribution of nanoclays in the matrix was showed by SEM micrographs. This observation helped in identifying the morphology of the nanocaly in the vinyl ester matrix.

Use of a stable carbon isotope to assess the efficiency of a drinking water treatment method with CO2

CO₂ gas with a special isotopic signature (δ¹³C = -35.2‰ vs. VPDB) was used as a marker to evaluate the efficiency of a drinking water treatment method and the effect of an ultrasonic (US) stirrer. This treatment was developed to prevent precipitation and corrosion effects in water-supply systems. The research work was performed using a laboratory-scale pilot plant that was filled with tap water. The stable isotope analyses of δ¹³C-DIC (Dissolved Inorganic Carbon) in the water samples indicated that the maximum content of added CO₂ gas in DIC was in the range of 35 to 45%. The use of the US stirrer during the entire experiment decreased the method's overall efficiency by 10%, due to degassing at a late stage of the experiment but accelerated the dissolution process in the early experimental stage.

Production of Natural Bioceramic from Land Snails

There are thousands of land snail species, ranging in size from 1 mm to the Giant African Snail growing up to a foot long. Two species, known as escargot, helix aspersa and helix pomatia, are commercially important. Helix pomatia is abundant in Turkey. Those snails are exported usually without shells. Shells are damped to trash sites or used as substitute food for animals. The shell is rich in calcium carbonate and some other minor minerals. Thus, snails’ shells can be used as a source for bioceramic production. So far, in the literature there are lot of papers about converting calcite and aragonite structures to hydroxyapatite (HA), like corals, sea shells, sea urchin and other sea creatures. However, there is very limited information about converting land snail shells to HA and other bioceramic phases. The aim of this work was to produce various phases of bioceramic materials from land snails’ shells which are left as a residue waste after their export procedures. Empty local land snails’ shells (helix pomatia) were collected in Istanbul. They were washed, dried, crushed and ball milled until a powder of 100 µm particles size was obtained. Raw powders were stirred at 80°C for 15 min on a hotplate. A second part of the raw powder was stirred with an ultrasonic stirrer at 80°C for 15 min in an ultrasonic equipment. Equivalent amount of H3PO4 was added drop by drop into the solution. The reaction lasted for 8h. Then, to evaporate the liquid part, the mixtures were put into an incubator at 100°C for 24 h and the resultant dried sediments were collected. The produced powders were analyzed with X-ray diffraction, IR and scanning electron microscope (SEM). The experimental results confirmed the formation of various Ca-phosphates, specifically monetite, fluorapatite and some other minor calcium phosphate phases. Bioceramic production from land snail is a reliable and economic way comparing to other tedious methods of producing synthetic HA and other various bioceramics phases.

Template synthesis of nanocomposite CdS with nonlinear optical properties

Nanoparticles of CdS were isolated by the treatment of thereaction mixture followed by the precipitation of CdS ina centrifuge, and the precipitate was washed with ether.Nanoparticles of CdS in pyridine were mixed in an ultrasonic stirrer with poly(methyl methacrylate) (PMMA) inan amount of 7% of the polymer weight. Then the suspension obtained was poured on a quartz support and dried at60 °C. The resultant sample was a film 0.3 mm thick. Theabsorption spectrum of the nanocomposite СdS—PMMAexhibits a shift to the blue region compared to that ofa single crystal of CdS. This shift is due to the quantumdimensional effect characteristic of nanoparticles of semiconductor crystals.

Precipitation-stripping of yttrium oxalate powders from yttrium-loaded HDEHP organic solutions using an ultrasonic stirrer

In previous papers, a kinetic study on the precipitation-stripping of yttrium oxalate powders from yttrium-loaded HDEHP solution had been conducted using a Lewis-type cell. In the present work, the precipitation-stripping of yttrium oxalate has been investigated in a reactor with an ultrasonic stirrer. This study shows the influence of several parameters on the precipitation yield, the solubility of yttrium in the aqueous phase, the nature, and the size distribution of the precipitated salt. The parameters which could vary were: initial concentrations of nitric (0–5 mol L −1) and oxalic (0.15–0.75 mol L −1) acids in the aqueous phase, initial concentrations of Y(HL 2) 3 (0.075–0.10 mol L −1) and HL (0.8–2.2 mol L −1) in the organic phase, nature of the organophosphorus acid used ((RO) 2PO 2H, R(RO)P0 2H with R = 2-ethylhexyl), temperature (24–60°C), ratio of the volumes of phases ( r = V o V a varying from 0.5 to 4). The nature of the precipitated salt depended on the concentrations of oxalic and nitric acids. At ambient temperature, neutral salt Y 2(C 2O 4) 3 · 10H 2O(s) was precipitated as aggregated platelets, the median diameter of which could vary from I to 4 μm according to the experimental conditions. Acidic salt YH(C 2O 4) 2 · 3H 2O(s) was precipitated in concentrated acidic aqueous media as platelets with a median diameter which could vary from 4 to 7 μm.