Mixture Of Paraffin Wax Research Articles

Design and Development of an Indigenous in-house Tissue-Equivalent Female Pelvic Phantom for Radiological Dosimetric Applications

Introduction: The present study is aimed to design and develop a tissue-equivalent pelvic phantom, mimicking the Indian female pelvic dimensions by means of locally available and cost-effective tissue substitutes having equivalent radiological properties. Materials and Methods: For the purpose of the study, the real female pelvic bones were embedded for preparation. Paraffin wax, Aloe-vera powder, purified borax, and sodium benzoate, were used to obtain the proper density and effective atomic number. A hollow three-dimensional outer surface and the internal organs moulds were fabricated using gypsona bandage. The internal organs moulds were filled with semi-solid paraffin wax mixture, stabilized, and then embedded with pelvic bones and internal organs at the right anatomical positions. The surface mould, along with the bones and internal organs, were stabilized in their position in the final form, and verified with computed tomography (CT). Results: The physical dimensions of the given female pelvic phantom were comparable with the mean dimensions of the Indian female pelvis. Furthermore this tissue-equivalent phantom was radiologically equivalent to the Indian human female pelvis in all respects. The CT numbers of the uterus, bladder, rectum, muscles, fats, bone, and cavities were 39.9, 30.5, 24.7, 34.6, -86.8, 578.6, and -220.9 HU, respectively. Furthermore, the relative electron densities of the muscle, fat and bones were 1.035, 0.913, and 0.779 in the phantom. Conclusion: The dimensions and physico-radiological properties of the tissue substitutes provided a good inhomogeneous female pelvic phantom differing in dimensions with imported pelvic phantoms. Therefore, this phantom can be used for radiological dosimetric applications.

INVESTIGATING THE USE OF PHASE-CHANGE MATERIALS FOR TEMPERATURE CONTROL DURING FAST FILLING OF HYDROGEN CYLINDERS

This paper explores the use of phase-change materials in the process of fast filling of hydrogen cylinders in order to limit the rise in the gas temperature by enhancing heat transfer from the gas. It is necessary to limit the temperature rise because the structural performance of the cylinder materials can be degraded at higher temperatures. Initially, two computational approaches for modeling the fast filling of hydrogen cylinders are presented and validated; the first is an axisymmetric computational fluid dynamics simulation and the second is a single-zone approach with one-dimensional conjugate heat transfer through the cylinder walls. The models are applied to study fast filling of a hydrogen-powered passenger car. The predictions show that the minimum safe fill time for Type III cylinders with aluminum liners is generally shorter than for Type IV cylinders with plastic liners, for given ambient and precooling temperatures. Alternatively, Type III cylinders require less precooling for a given fill time. Introduction of a phase-change material heat sink is assessed as a means of reducing the fill time for Type IV cylinders. Paraffin-based phase-change materials are considered. The predictions show that the use of pure paraffin wax does not help in reducing the gas temperature due to its low thermal conductivity, however materials with improved thermal conductivity, for example, mixtures of paraffin wax and graphite, can facilitate reduced fill times. Without use of phase-change material it is not possible to reduce the fill time of Type IV cylinders below three minutes unless the gas supply is precooled. While the fill time can be reduced by precooling the gas supply, the phase-change material reduces the degree of precooling required for a given fill time by 10–20 K, and reduces the minimum theoretical power consumption of the cooler by 50–100%, depending on the ambient temperature.

Determination of effective atomic numbers from mass attenuation coefficients of tissue-equivalent materials in the energy range 60 keV-1.33 MeV

The main aim of this study was to establish a cost-effective tissue-equivalent material for phantom fabrication. Effective atomic numbers (Zeff) and effective electron densities (Neff) were calculated based on mass attenuation coefficient values. The linear and mass attenuation coefficients of two samples of paraffin wax and NaCl compositions were measured using Si detector for NaI (Tl) detector of 1.5” resources. Radioactive source was placed in front of detector and the sample was placed between the source and the photomultiplier tube (PMT) of the detector. The real time was set for 6000 seconds. The photopeak, full width at half maximum (FWHM) and net area of photopeak were measured using Meastro software. The attenuation coefficient values obtained from this study were used to calculate Zeff and Neff of paraffin wax and NaCl compositions. The measured results were compared with the theoretical values from XCOM and ICRU Report 44. The relative percentage difference of mass attenuation coefficients between experimental and human tissue for both paraffin wax and NaCl mixture are below 5%, whereas the relative percentage difference of Zeff and Neff are above 5%. The measured values of Zeff and Neff of paraffin wax and NaCl help us to establish the optimal mixtures to fabricate a cost-effective tissue-equivalent material.

Theoretical and experimental study of aluminum foils and paraffin wax mixtures as thermal energy storage material

This study analyzes the effect of increased thermal conductivity in energy storage, using paraffin wax with 8% w/w of aluminum foils, obtained from waste materials. Three configurations previously not published of the aluminum foil were tested: stripes, horizontal perforated disks and vertical perforated foils. The aluminum foils doubled the thermal conductivity, achieving values of 0.63 W/mK, without significant statistical influence of the metallic configuration inside this material. Solidification time depended on the configuration of the aluminum foils, where differences of up to 38% were detected between horizontal perforated disks and stripes. The equations for the solidification process were numerically solved in Matlab using the finite volume method, finding good agreement for the simulated output air temperature when compared with experimental values (relative error <10 %). Later, a thermal energy accumulator was designed and assessed, which consisted of 12 cans with paraffin wax, using the horizontal perforated disks configuration. The energy stored by the phase change material was removed with air velocities between 0.5 − 1.5 m/s, reaching efficiencies close to 90% for the maximum air velocity.

Metal Injection Moulding of Superelastic TiNi Parts

TiNi shape-memory properties are successfully used today for the fabrication of various technical devices. The limited machinability and high cost of TiNi encourage the use of near-net shape production techniques such as metal injection moulding. In this work TiNi alloys tensile test specimens are produced by metal injection moulding from pre-alloyed powders. A binder based on a mixture of polyethylene, paraffin wax and stearic acid is used. Parts with a density of about 96.6% of theoretical density are obtained. Scanning electron microscopy coupled with EDX measurements reveals a microstructure consisting of a TiNi matrix with small Ti4Ni2Ox and TiC inclusions. DSC and X-ray diffraction observations indicate the presence of additional Ni4Ti3 precipitates. The parts exhibit full superelasticity at room temperature even for strains of up to 4%, without the need for additional thermal post-treatments. Ultimate tensile strengths up to 980 MPa are obtained.

Experimental study of rotating dry slag granulation unit: Operating regimes, particle size analysis and scale up

Blast furnace slag is a high-value by-product of the iron and steel industry. It leaves the plant at a very high temperature and possesses a large quantity of high-grade energy. One of the promising methods to extract this energy is dry slag granulation. In this study, the effectiveness of dry slag granulation was studied using a mixture of rosin and paraffin wax as an analogue for blast furnace slag. The effects of various parameters such as rotational speed of the disc, diameter of the disc and flow rate of the molten liquid have been studied. Different ranges of operating conditions in terms of non-dimensional numbers for fiber formation and particle formation were determined. This helps us determine the operating conditions under which particle formation is ensured. The study shows that with an increase in the rotational speed or disc diameter the average particle diameter decreases whereas with an increase in the flow rate the average particle diameter increases. The design of a granulation unit for a commercial plant utilizing the data from lab scale experiments is discussed.

A TCD-based technique for experimental study of mass transfer in a gas–solid fluidized bed with liquid injection

A technique using the measurement of gas phase concentrations for the study of mass transfer in gas–solid fluidized beds has been developed. This method uses thermal conductivity detectors (TCDs) to measure local concentrations of a gaseous species as it evolves from a continuously sprayed binary liquid into the system. The binary liquid, a mixture of paraffin wax and n-heptane, was chosen to be a low temperature analogue of bitumen, which is thermally converted into lighter liquid products using the FLUID COKING™ process. In both the commercialized process and the low temperature analogue, the volatile fraction of the liquid feed is released into the gas phase, while the heavy components remain in the bed and eventually solidify. The n-heptane vapor concentration was continuously measured using three TCDs, sampling from different locations in a 4-m tall, 0.4m×0.1m fluidization column. By varying operating conditions such as the superficial gas velocity, bed temperature, and air-to-liquid ratio, the present work successfully demonstrated the ability to measure changes in mass transfer conditions in a fluidized bed continuously and accurately with fast response.

Electrode for Voltammetric Evaluation of Insoluble Particles

A working electrode was developed to test the electrochemical behavior of insoluble particles in aqueous acidic and basic electrolytes. The hydrogen evolution reaction (HER), oxygen reduction reaction (OER), and pseudocapacitive behavior of nickel phosphide, nickel oxide, and cobalt oxide were evaluated. The electrode consists of a coiled copper wire in a (55:45 wt. %) mixture of graphite and paraffin wax, housed in either glass or polyvinyl fluoroethylene (PTFE) tubing. The malleability of the electrode surface allows for particles to be directly embedded into the surface without the use of binder materials such as Nafion or PTFE. The electrochemical behavior of modified and unmodified electrodes of both the developed carbon-wax electrode and a commercially available glassy carbon electrode (GCE) is presented. Cyclic voltammetry, linear sweep voltammetry, and chronopotentiometry were employed for electrochemical investigation into the hydrogen evolution reaction, oxygen evolution reaction, and pseudocapacitive behavior of nickel phosphide (NiP2), nickel oxide (NiO) and cobalt oxide (Co3O4) on both working electrode types. The PTFE electrodes performed well in both acidic and basic media and their performance is comparable to the GCE. The newly developed electrodes displayed reproducible electrochemical behavior and provide a method to evaluate insoluble particles voltammetrically.

Analogue experimental study on centrifugal-air blast granulation for molten slag

Blast furnace slag is a by-product in iron and steel production process which has a high yield with extremely high discharge temperature. Aiming at energy and water saving as well as emission reduction, dry granulation technique appears to be a good application for the treatment of blast furnace slag. In this study, a granulation technique combining a high-speed rotating cup with air blast is proposed. The performance of this design was investigated by adopting a mixture of rosin and paraffin wax as the analogue of blast furnace slag. The effects of rotating speed of the atomizer, liquid flow rate and blast air flow rate on particle size, particle mass distribution and fiber mass fraction were studied. The effect of the function of air blast on the granulation performance was particularly discussed. The results showed that at a higher rotating speed and a smaller liquid flow rate, smaller particles can be easily obtained, yet the fiber mass fraction also increases. However, the increasing blast air leads to the increase of particle size and fiber mass fraction. For the operating conditions tested in this study, over 60% of total mass of particles fall within the size range of 0.5–1 mm, which means that the present system has a good performance in centrifugal granulation.

SU‐F‐BRE‐04: Construction of 3D Printed Patient Specific Phantoms for Dosimetric Verification Measurements

Purpose:To validate a method to create per patient phantoms for dosimetric verification measurements.Methods:Using a RANDO phantom as a substitute for an actual patient, a model of the external features of the head and neck region of the phantom was created. A phantom was used instead of a human for two reasons: to allow for dosimetric measurements that would not be possible in‐vivo and to avoid patient privacy issues. Using acrylonitrile butadiene styrene thermoplastic as the building material, a hollow replica was created using the 3D printer filled with a custom tissue equivalent mixture of paraffin wax, magnesium oxide, and calcium carbonate. A traditional parallel‐opposed head and neck plan was constructed. Measurements were performed with thermoluminescent dosimeters in both the RANDO phantom and in the 3D printed phantom. Calculated and measured dose was compared at 17 points phantoms including regions in high and low dose regions and at the field edges. On‐board cone beam CT was used to localize both phantoms within 1mm and 1° prior to radiation.Results:The maximum difference in calculated dose between phantoms was 1.8% of the planned dose (180 cGy). The mean difference between calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was 1.9% ± 2.8% and −0.1% ± 4.9%, respectively. The difference between measured and calculated dose was determined in the RANDO and 3D printed phantoms. The differences between measured and calculated dose in each respective phantom was within 2% for 12 of 17 points. The overlap of the RANDO and 3D printed phantom was 0.956 (Jaccard Index).Conclusion:A custom phantom was created using a 3D printer. Dosimetric calculations and measurements showed good agreement between the dose in the RANDO phantom (patient substitute) and the 3D printed phantom.

Taurine-EVA copolymer-paraffin rods dosimeters for EPR high-dose radiation dosimetry

Abstract Taurine/EPR rods (3 × 10 mm) have been prepared by a simple technique in the laboratory where taurine powder was mixed with a molten mixture of paraffin wax and an ethylene vinyl acetate (EVA) copolymer. The binding mixture EVA/Paraffin does not present interference or noise in the EPR signal before or after irradiation. The rods show good mechanical properties for safe and multi-use handling. An EPR investigation of radiation induced radicals in taurine rods revealed that there are two types of radicals produced after exposure to gamma radiation (60Co). EPR spectra were recorded and analyzed - also the microwave power saturation and modulation amplitude were studied and optimized. Response of taurine to different radiation doses (1.5-100 kGy) was studied and found to follow a linear relationship up to 100 kGy. Radiation induced radicals in taurine persists and showed a noticeable stability over 94 days following irradiation. Uncertainities associated with the evaluation of radiation doses using taurine dosimeters were discussed and tabulated. It was found that taurine possesses good dosimetric properties using EPR spectroscopy in high doses in addition to its simple spectrum.

Microstructures induced microwave resonance peak shift of Co/Al2O3 nanocomposites prepared by ball milling

Microstructures play an important role in materials’ functional performances. In this work, the microstructures including interfaces induced microwave resonance peak shift of Co/Al2O3 nanocomposites is studied. Nanosized Co/Al2O3 composites were successfully fabricated via direct ball milling. The hcp and fcc Co phases coexist for a long milling duration and the interface effect is prominent in the nanocomposites. The measured relative complex permittivity of the Co/Al2O3 nanocomposite–paraffin wax mixture indicates that a high electrical resistivity and a dielectric loss exist in the Co/Al2O3 nanocomposites. The dielectric loss mainly arises from the polarization of the metal/insulator interfaces. The imaginary part of the relative complex permeability of the mixture exhibits a broad resonance peak centered at 8.3GHz which originates from the natural resonance of Co. In comparison to the reported value 6.5GHz, the shift of the resonance peak to higher frequency can be attributed to the surface anisotropy induced by prominent interface effects, which was confirmed by NMR. The position of the resonance peak results from the competition between the surface anisotropy and the dipolar coupling interaction of the Co grains. The calculated reflection loss curves show that the reflection loss value of the Co/Al2O3 nanocomposite–paraffin wax mixture can reach −10dB in a broad frequency range. The improved microwave characteristics are closely related to the microstructures, and can be tailored by controlling the content of Co and the thickness of the sample.

Magnesium lactate mixed with EVA polymer/paraffin as an EPR dosimeter for radiation processing application

The dosimetric characteristics of γ-radiation-induced defects in magnesium lactate (ML) rods (3.5mm×10mm) formulated by mixing ML with molten mixtures of paraffin wax and EVA copolymer have been investigated using electron paramagnetic resonance (EPR). The EPR spectrum of irradiated ML rods was characterized by a quartet signal with the spectroscopic splitting g-factor of 2.0048±0.0003 at 0.4mT. The useful dose range of the rod dosimeter was 100Gy to 80kGy. The mass attenuation coefficient, μ/ρ, and the mass energy-absorption coefficient, μen/ρ, versus energy in the range of 10keV to 20MeV indicate that the prepared ML dosimeter is typically adipose tissue equivalent overall this energy range. The overall combined uncertainties (at 2σ) associated with routine dose monitoring in the dose range of 0.1–10kGy and 10–80kGy were found to be 6.14% and 6.36%, respectively.

Novel fabrication of pressure-less sintering of translucent powder injection molded (PIM) alumina blocks

A new method of fabricating translucent alumina brackets using powder injection molding (PIM) is reported. Alumina powder was mixed with MgO, La 2O 3, and Y 2O 3 to control grain size and porosity. The powders were mixed with a binder consisting of a mixture of paraffin wax and polyethylene in a 1:1 ratio to make feedstock for injection molding. The total amount of binder was limited to 14 wt% to minimize shrinkage and cracking after sintering. After injection molding, debinding was performed using the wicking method and samples were sintered in a vacuum at 1700 °C to achieve high density. Ultimately, translucent corundum was fabricated. The sintering additives resulted in a decrease in porosity and an improvement in translucency by promoting grain growth during pressure-less sintering. After sintering, Vickers hardness, bending strength, density, and transmittance of the fabricated parts were measured to show that those values were comparable to those of the commercially available dental brackets. Therefore, the translucent alumina block was successfully fabricated using PIM method to be potentially used as a dental bracket.

Magnetic and electromagnetic properties of composites of iron oxide and Co–B alloy prepared by chemical reduction

Magnetic and electromagnetic properties were investigated on the composites of iron oxide and Co–B alloy, which were prepared by a modified chemical reduction method. The composites are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). The complex electromagnetic parameters (permittivity ε r= ε r′+j ε r″ and permeability μ r= μ r′+j μ r″) of paraffin mixed composite samples (paraffin:composites=1:1 in mass ratio) were measured in the frequency range 2–18 GHz by vector network analyzer. The measured real part ( ε r′) and imaginary part ( ε r″) of the relative permittivity show two resonant peaks in the range of 2–18 GHz. The imaginary parts of relative permeability ( μ r″) of all samples exhibited one broad resonant peak over the 2–8 GHz range. The μ r″ of samples with higher molar ratio of Co to Fe (C and D) shows negative values within 13–18 GHz, which exhibit resonant and antiresonant permeabilities simultaneously. Calculation results indicated that the reflection loss values of the composites and paraffin wax mixtures are less than −10 dB with frequency width of about 6 GHz at the matching thickness.

Paraffin wax mixtures as phase change materials

Melting of the binary mixture system of tetradecane and hexadecane in Differential Scanning Calorimetry (DSC) cell has been investigated experimentally and numerically. Different concentrations of tetradecane–hexadecane paraffin mixture were studied. It is found that the phase change process of the binary mixture takes place over a temperature range and the temperature range depends on both the heating rate and the mixture composition. The proposed study shows also that for the same concentration of tetradecane and using various heating rates, we will be able to predict the solidus and liquidus temperature of the binary mixture from DSC curves.

An in situ heater for a phase-change-material-based actuation system

This paper reports efforts to develop paraffin actuators that rely on a phase change to achieve actuation. While paraffin phase-change actuators have existed for some time, this work relies on heating the paraffin in situ, rather than using external heaters. Graphite is used to create an in situ heater that utilizes resistive heating as a voltage is applied across the graphite–paraffin wax mixture. The main motivation behind this work is to reduce the actuation time and power required. An added advantage of the developed in situ heater is the use of printed circuit board technology to fabricate the prototypes rapidly and in a cost-effective manner. A video microscope and IR camera are used to characterize the performance of the actuators built in this work. Different compositions of graphite in paraffin wax are used to measure the actuator performance characteristics such as actuation time, actuation height and power required. Both dc and a pulsed power input are used to test the prototypes. Comparison with a similar actuator that utilizes a thin film heater shows a 90% reduction in actuation time for similar power usage. The actuator developed as part of this work resulted in 0.577 mm dot height at 0.69 W power input in 6 s translating to ∼4 J/actuation for an actuator chamber of 2.82 µL. A new performance metric, ‘effective actuation time (W s−1 mm−4)’, is used to compare the performance of this technology with other phase-change-material-based actuators, and the actuator developed in this work is found to be 10 to 200 times better.

Microwave characteristics of Co/TiO2 nanocomposites prepared by mechanochemical synthesis

Abstract Co/TiO 2 nanocomposites were prepared by mechanochemical synthesis. The microwave characteristics of the Co/TiO 2 nanocomposite–paraffin wax mixture were studied in the 0.1–18 GHz frequency range. The measured relative complex permittivity of the Co/TiO 2 nanocomposite–paraffin wax mixture indicates a higher electrical resistivity of the Co/TiO 2 nanocomposites compared to the pure Co. The imaginary part of the relative complex permeability of the mixture exhibits a broad resonance peak at 5.1 GHz which results from the natural resonance of Co. The Henkel plots confirm that the magnetic dipolar coupling interaction between the Co grains in the nanocomposites leads to the shift of resonance peak to a lower frequency. The calculated reflection loss curves show that the minimum reflection loss value of the Co/TiO 2 nanocomposite–paraffin wax mixture can reach −27 dB at 3.5 GHz with 3 mm sample thickness.

Magnetic and microwave properties of cobalt nanoplatelets

The Co nanoplatelets of 120 nm in diameter and 10 nm in thickness exist in both fcc and hcp crystal structures at room temperature. The saturation magnetization of the Co nanoplatelets is lower than that of the bulk Co because of the existence of the oxide layer. The coercivity is higher than that of the bulk Co. The equilibrium magnetic configuration of a single Co nanoplatelet without external magnetic field is a vortex structure, regardless of hcp or fcc crystal structure. The Co nanoplatelets were coated by MnO 2. The microwave properties of the MnO 2-coated Co nanoplatelet composites and paraffin wax mixtures were measured in the 0.1–18 GHz frequency range. The complex permeability of the sample shows two broad resonance peaks and the complex permittivity of the sample shows one resonance peak in the frequency range of 0.1–18 GHz. The numerical simulations show that the reflection loss values of the MnO 2-coated Co nanoplatelet composites and paraffin wax mixtures are less than −12 dB in the 2–11.5 GHz frequency range.

Dose mapping of complex-shaped foods using electron-beam accelerators

Obtaining a uniform dose in inherently irregularly shaped foods, such as an apple, is very difficult, and development of accurate dose calculation methodologies is needed. The objective was to determine the most uniform irradiation treatment on apple surrogates and GAFCHROMIC ® HD-810 films using electron beams from a 2 MeV Van de Graaff (VDG) accelerator, a l0 MeV Linear Accelerator (LINAC), and X-rays from a 5 MeV LINAC. We manufactured a solid 3-D apple-surrogate from a mixture of paraffin wax, chloroform, and methyl yellow biological indicator. The surrogate showed electron interaction characteristics very similar to an actual apple. Evaluation of food positioning strategies in front of the e-beam source of the VDG demonstrated that tilting axial rotation ensure uniform dose distribution of the entire surface of the surrogate, even reaching the critical regions of the stem and calyx ends. Irradiation with 10 MeV dual e-beam showed uniform penetration (top to bottom) in the HD-810 film and surrogates. X-ray irradiation completely penetrated the apple surrogate (top to bottom) showing excellent lateral uniformity at different penetration depths. The measured dose distributions in the surrogate showed good agreement with the calculated doses. These results support the validity of using chemical surrogate techniques for accurate planning of food irradiation treatments.