Concentration Of Barium Sulfate Research Articles

Production of Bone Cement Composite from Polymethyl Methacrylate Produced in Laboratory Scale

Bone cement is an indispensable material in orthopedic medicine. In Indonesia, the fulfillment of bone cement needs still depends on imports from other countries. Polymethyl methacrylate (PMMA) is one of the main ingredients of bone cement which can be made from suspension polymerization of methyl methacrylate monomer (MMA). Therefore, this study aims to develop a technique for producing bone cement from PMMA. The production of bone cement consists of (1) the manufacture of PMMA, (2) the mixing of solid mixtures, (3) the mixing of solid mixtures and liquid mixtures, and (4) the molding of bone cement composites. The concentrations of barium sulfate (BaSO4) used were 7%, 9%, and 11% by weight. Composite products were analyzed by Scanning Electron Microscopy (SEM), Proton Nuclear Magnetic Resonance (H-NMR), and Compressive Strength. The increase of BaSO4 can trigger more smooth surface of bone cement composite. The tacticity from H-NMR shows that the bone cement dominantly consists of syndiotactic (58.83-59.91%) molecular arrangement. The highest compressive strength was 84.2 MPa which was obtained in 9% BaSO4 weight.

Microfluidic Fabrication and Characterization of Radiopaque Barium Sulfate Polyethylene Glycol‐Based Hydrogel Microspheres

The objective of this study was to fabricate and characterize monodisperse polyethylene glycol (PEG)‐based barium sulfate hydrogel microspheres for applications in prostatic hyperplasia and prostate cancer treatments. Currently, catheter embolization procedures used in prostatic hyperplasia treatments employ non‐opaque microspheres with a tracer dye, which can result in off‐target embolization. The goal of this study was to fabricate monodisperse, radiopaque microspheres that can be easily tracked via microcomputed tomography (microCT) during embolization procedures. The hydrogel microspheres were fabricated using 4‐arm PEG‐Acrylate macromer and PEG‐dithiol crosslinker solutions in a custom‐designed microfluidic chip that allowed for on‐chip mixing and gelation of a timed‐gelation system, greatly improving bead fabrication throughput and reproducibility. Microspheres were loaded with 1 μm barium sulfate particles and bovine serum albumin to aid in barium suspension. Microspheres were imaged both before and after washing with buffer using an inverted microscope to measure microsphere diameter and degradation. Settling of barium sulfate solutions was measured qualitatively in microcentrifuge tubes. Monodisperse, barium sulfate loaded‐hydrogel microspheres were produced, the size of which could be controlled by modulating the inlet flow rates of the dispersed and continuous phases. Furthermore, the results show that the opacity of the barium sulfate microspheres increased with increased barium sulfate concentration. In conclusion, the results indicate that this study successfully fabricated monodisperse and opaque barium sulfate PEG‐based hydrogel microspheres. Future experiments will evaluate the radiopacity under microCT, swelling and degradation properties, and injectability of the hydrogel microspheres to help further confirm the application of these microspheres in catheter embolization procedures.

Evaluating scale deposition and scale tendency of effluent water mix with seawater for compatible injection water

Water injection technique is contributing millions of oil barrels on a daily basis to the global oil supply; one of the challenges faced by such an important production method is scale buildup due to the different dissolved solids and high salinity of the injected water. For produced water or effluent water, pretreatment is a critical step before the injection process to reduce the risk of scale potential and well formation damage. One of the beneficial treatments of the effluent water is to be mixed in a compatible ratio with seawater, especially for those countries with easy access to seawater. Thus, the objective is to find a compatible mix ratio with seawater as one way of solving effluent water reuse without increasing the risk of scale and formation damage during water injection operation. In this study, effluent water samples were collected from different oilfield geographical locations in Kuwait, and then the samples were analyzed in the laboratory for their physical and chemical properties to select the most compatible one for mixing with seawater. The selected effluent water was then mixed with seawater in 1:1 ratio to evaluate the compatibility of the mix in terms of sulfate formation and scale tendency. The selected North field/seawater was tested under 75 ºC and 1000 PSi in an autoclave. The filtered precipitates were characterized by energy-dispersive spectroscopy (EDS) and scanning electronic microscope (SEM) micrographs. Further, the formations of sulfate were detected by X-ray diffraction (XRD). The OLI ScaleChem software was used to investigate the composition of mineral scales that may occur in the water mix at different ratios ranging from 0 to 100% to compare it with the actual water mix finding. In the effluent waters comparison part, North field water showed low pH (4.6) and alkalinity, as well as moderate TDS (190,000 MG/L). The main constituents of the scale deposited at the selected water mixing ratio were calcium sulfate CaSO4 and silicon oxide detected by XRD. However, the amount of barium sulfate was not presented in the precipitates indicating that all of it went in the liquid phase. The study concludes that at downhole conditions, the compatible mix of North Kuwait effluent water with seawater has high risk of barium sulfate in comparison with other common scale such as calcium sulfate, calcium carbonate and strontium sulfate (SrSO4). Also the study revealed that the prediction of different seawater ratios showed that at 70% seawater concentration, the barium sulfate concentration drops and consequently the scale risk reduced.

The use of Thiel embalmed human cadavers for retrograde injection and visualization of the lymphatic system.

In order to provide an alternative for fresh frozen specimens to map the lymphatic system, the possibility of using Thiel embalmed specimens for this purpose was explored. The thoracic duct was used to investigate if retrograde injection of contrast agent was possible in Thiel embalmed specimens and to verify up to which diameter lymphatic vessels could be reconstructed and rendered in 3D, after CT scanning. 3D renderings were used for digital diameter measurement, to determine the smallest lymphatic diameter that could still be visualized on CT. Finally, the contrast agent concentration was adapted based on the findings during image reconstruction and 3D rendering. All Thiel embalmed specimens proved suitable for retrograde injection of contrast agent into the thoracic duct and all 3D renderings perfectly overlapped with the dissection pictures. The smallest diameter of contrast filled lymphatics that could be reconstructed and rendered in 3D was 0.23 mm. Increasing the concentration of barium sulfate from 10 to 50% reduced the postprocessing time needed to render a "clean" 3D structure, following automatic segmentation based on grey values, by 95%. The authors would recommend the use of Thiel embalmed specimens for mapping the lymphatic system, as these specimens do not show the rapid putrefaction that occurs in fresh frozen specimens, thus greatly facilitating experimental planning.

Synthesis and characterization of a new vertebroplasty cement based on gold-containing PMMA microspheres

There are a number of drawbacks to incorporating large concentrations of barium sulfate (BaSO4) as the radiopacifier in PMMA-based bone cements for percutaneous vertebroplasty. These include adverse effects on injectability, viscosity profile, setting time, mechanical properties of the cement and bone resorption. We have synthesized a novel cement that is designed to address some of these drawbacks. Its powder includes PMMA microspheres in which gold particles are embedded and its monomer is the same as that used in commercial cements for vertebroplasty. In comparison to one such commercial cement brand, VertaPlex™, the new cement has longer doughing time, longer injection time, higher compressive strength, higher compressive modulus, and is superior in terms of cytotoxicity. For augmentation of fractured fresh-frozen cadaveric vertebral bodies (T6-L5) using simulated vertebroplasty, results for compressive strength and compressive stiffness of the construct and the percentage of the volume of the vertebral body filled by the cement were comparable for the two cements although the radiopacity of the new cement was significantly lower than that for VertaPlex™. The present results indicate that the new cement warrants further study.

Concentration modulated skin marker for radiotherapy treatment planning process

Background and purposeFor conformal radiotherapy, it is feasible to achieve high accuracy in contouring the outline of the target volume in treatment planning process. In contouring process, target volume is occasionally defined by means of either surgical clips or skin marker during patient anatomical data acquisition. Treatment planning systems are predicting invalid radiation dose distributions by using surgical clips and skin marker within the patient. Purpose of this study is the production of new skin marker which affects less dose distributions of electron beam. Materials and methodsThe influences of lead and commercial markers on dose calculations in a 3D treatment planning systems were investigated in terms of electron beam energy and dose profile depth. Dose deviation with commercial marker was observed to smaller than lead marker. However this dose deviation was still at big value. In order to reduce of this value, barium sulfate suspension and ultrasound gel were mixed with different volumetric ratio. With the purpose of acception the most suitable marker for radiation therapy, obtained new suspensions were investigated in terms of visibility and dose deviation. ResultsB:G/1:10 marker was determined to cause optimum visibility and the lowest dose deviation on dose calculations in terms of electron beam energy and dose profile depth. ConclusionsAppropriate marker, mixture of substances such as barium sulfate suspension and ultrasound gel can be produced. This marker is both ease of usage and practical and economical. Each clinic can prepare marker which is peculiar to suspension with different concentration of substance for specific visibility. But, it should be taken into account resultant dose deviation to beam calculation depending on barium sulfate concentration.

A Simple Method Based on the Application of a CCD Camera as a Sensor to Detect Low Concentrations of Barium Sulfate in Suspension

The development of a simple, rapid and low cost method based on video image analysis and aimed at the detection of low concentrations of precipitated barium sulfate is described. The proposed system is basically composed of a webcam with a CCD sensor and a conventional dichroic lamp. For this purpose, software for processing and analyzing the digital images based on the RGB (Red, Green and Blue) color system was developed. The proposed method had shown very good repeatability and linearity and also presented higher sensitivity than the standard turbidimetric method. The developed method is presented as a simple alternative for future applications in the study of precipitations of inorganic salts and also for detecting the crystallization of organic compounds.

Barium Sulfate Effects on the Electrochemical Behaviors of Nanostructured Lead Dioxide and Commercial Positive Plates of Lead-Acid Batteries

Positive electrode with uniform lead dioxide nanostructures directly synthesized by cyclic voltammetry (CV) method on the lead substrate in 1 M sulfuric acid solution including different concentration of barium sulfate. The effect of potential scan rate, sulfuric acid and barium sulfate concentration were studied on the morphology and particle size of lead dioxide using scanning electron microscopy (SEM) and X-ray diffraction techniques (XRD). The effect of barium sulfate was studied on the CV parameters including anodic peak current (I p a ), cathodic peak current (I p c ), anodic peak potential (E p a ) and cathodic peak potential (E p c ) during synthesis process. Finally, the effect of barium sulfate on the discharge capacity and cycle life of nanostructured positive electrodes and commercial positive plates was investigated. Both CV and battery test results showed that barium sulfate with concentration of 1 × 10−5 M can be used as suitable additive for positive paste of lead-acid batteries.

Radiation dose in mass screening for gastric cancer with high-concentration barium sulfate compared with moderate-concentration barium sulfate

Recently, high-concentration barium sulfate has been developed and is used in many medical facilities. This study compared radiation dose using high-concentration and moderate-concentration barium sulfate. The dose was evaluated with an experimental method using a gastric phantom and with a clinical examination. In the former, the dose and X-ray tube load were measured on the phantom with two concentrations of barium sulfate. In the latter, the fluoroscopic dose-area product (DAP), the radiographic DAP and their sum, the total DAP, were investigated in 150 subjects (112 males, 38 females) treated with both concentrations of barium sulfate. The effective dose was calculated by the software of PCXMC in every case. The results of the experimental evaluation indicated that the effective dose and X-ray tube load were greater with high-concentration barium sulfate than with moderate-concentration barium sulfate (p < 0.05). The results of the clinical evaluation indicated that the fluoroscopic DAP was greater with moderate-concentration barium sulfate than with high-concentration barium sulfate (p < 0.05), but the radiographic DAP was quite the reverse, so the total DAP and effective dose were almost same with both concentrations of barium sulfate. We conclude that high-concentration barium sulfate does not increase radiation dose in mass screening for gastric cancer.

Performance of polysulfone membrane dialyzers and dialysate flow pattern

It is important to observe the flow pattern of dialysate when evaluating dialyzer function and developing the most appropriate design. We investigated dialysate flow through two polysulfone membrane dialyzers (TS-UL [Toray Medical] and APS-S [Asahi Medical]) by computed tomography (CT), with barium sulfate as the contrast medium. We also performed a clinical comparison of these two dialyzers. For the in vitro experiment, after confirming the steady-state flow of mock blood (xanthan gum solution; 200 ml/min) and dialysate (500 ml/min), fresh dialysate, containing 5% (w/v) barium sulfate was perfused, and longitudinal CT scans of the dialyzer were obtained. Then the concentration of barium sulfate was measured (in Hounsfield units) in three fixed regions of interest. For the in vivo experiment, 12 patients on stable hemodialysis who had been using the APS-S for more than 1 month were switched to the TS-UL for 1 month and changes in various parameters were assessed. The distribution of dialysate was homogeneous on CT scans of the TS-UL, but not on scans of the APS-S. The dialysate concentration curves for the three regions of interest were similar with the TS-UL, but not with the APS-S. Clearance of urea nitrogen and albumin loss were both significantly higher with the TS-UL than with the APS-S. The decrease in alpha 1-microglobulin was larger with the TS-UL than with the APS-S, but not significantly. Clearance of substances over a wide range of molecular weights was higher with the TS-UL than with the APS-S, and differences in the design of the dialysate compartment may have been involved in this feature.

Histological and radiographic evaluation of polymethylmethacrylate with two different concentrations of barium sulfate in a sheep vertebroplasty model

Percutaneous vertebral augmentation with PMMA has been widely performed and usually provides good pain relief and stabilization of fractured vertebrae. Adequate visualization of PMMA during injection is desirable to minimize cement extravasation, so contrast agents such as barium sulfate are commonly added to the PMMA. The aim of this study was to evaluate the differences of histology and radiographic visualization when different concentrations of barium sulfate are mixed with PMMA. Six sheep were utilized in this study. Three vertebrae of each animal were exposed via retroperitoneal approach, and a cavity was created and then filled with either 10% or 30% BaSO4/PMMA, or left empty. Vertebrae were harvested and analyzed radiographically and histologically 12 and 90 days after surgery. Average CT value of the 30% BaSO4/PMMA group was 2.4-fold higher than that of the 10% BaSO4/PMMA group. Foreign-body giant cells were recognized around BaSO4particles at 90 days in the 30% BaSO4 group, whereas few particles were recognized in the 10% group at 90 days, or in either group at 12 days. A very mild giant-cell reaction is induced by a higher concentration of BaSO4 in PMMA, but the marked improvement in cement visualization by increased BaSO4 may be important to minimize more serious complications of cement extravasation during PMMA injection.

Radiographic gastrointestinal contrast study in the ostrich (Struthio camelus).

Ten gastrointestinal contrast studies were performed with barium on seven clinically healthy ostriches. Concentrations of 25-100% w/vol liquid barium sulfate at 7 and 10 ml/kg were administered by stomach tube after withholding food for 16 h. A 6-frame technique for left-to-right lateral views in standing and a 3-frame technique for the dorsoventral views in sternally recumbent adult ostriches were used for survey and contrast radiographs. Objectives were to describe the appearance of the normal gastrointestinal tract with contrast radiography and to provide a guideline for optimal dosage and concentration of barium sulfate as well as a reliable protocol for frequency of radiographs. Structures that were consistently identified included the esophagus, proventriculus, ventriculus, duodenum, jejunum, proximal, and distal rectum. Due to the superimposition of the remainder of the small intestine, individual components were difficult to differentiate. The caeca were inconsistently highlighted and only for a short time. The ventral pouch of the coprodeum never filled with contrast medium.

Modelling temperature and salt concentration distribution in membrane distillation feed channel

The method of Ilias and Govind for modeling ultrafiltration was modified to model a flat sheet air gap membrane distillation module with empty channels. In the membrane distillation process, there is mutual dependence of the momentum and heat transport processes. It complicates the solution of the governing equations and often leads to using simplifications. The developed method allows solving hydrodynamic and heat transport equations without additional assumptions for decoupling the equations with permeation taken into account. Velocity and temperature distributions inside the membrane feed channel were obtained, as well as the concentration profiles of a sparingly soluble salt (barium sulfate). Severe temperature polarization, occurring under poor mixing conditions, has been shown. Supersaturation profiles of barium sulfate are shown to be dependent on the inlet temperature of the membrane channel, and at certain conditions a maximum value of the barium sulfate concentration lies in the bulk of the channel, rather than at membrane surface.

Oral administration of a low-cost negative contrast agent: a three-year experience in routine practice.

A low cost, well tolerated, and effective gastrointestinal contrast agent is needed for abdominal MRI. The authors tested, in vitro and in routine practice, a mixture of 192 g of barium sulfate (Micropaque HD oral, Guerbet, France) diluted in 500 ml of gastric antacid (Maalox, Rohrer, Fort Washington, PA). Its T1 and T2 relaxation times were 324 and 14 msec, respectively (.2 T). This contrast agent was used in routine practice in 789 patients (.5 T). It had a low signal intensity in 86% and 82% of the cases on T1- and T2-weighted sequences, respectively. No side effect due to magnetic susceptibility was seen, even with gradient-echo sequences. The dilution of barium sulfate in gastric antacid, instead of water, causes a low signal intensity on all sequences for a low barium sulfate concentration (38% w/v). This product is an effective and low cost contrast agent in routine practice.

Radical Graft Polymerization of Vinyl Monomers onto Barium Sulfate Initiated by Azo Groups Introduced onto the Surface

To modify the surface of barium sulfate, the radical graft polymerization of vinyl monomers initiated by azo groups introduced onto the surface was investigated. The introduction of azo groups onto the surface was achieved by the direct condensation of carboxyl group of 4,4'-azobis(4-cyanopentanoic acid) with 12-hydroxystearate groups on modified barium sulfate using N,N'-dicyclohexylcarbodiimide as a condensing agent. It was found that the radical polymerizations of methyl methacrylate (MMA), styrene, and N-vinylcarbazole were initiated by the azo groups introduced onto the surface, and the corresponding polymers were grafted onto the surface based on the propagation of grafted polymer from the surface : the percentage of PMMA grafting onto the surface reached 25.3% at 70°C after 1.5 hours and the grafting efficiency was 21.4%. The polymerization rate (R p ) of styrene initiated by the surface azo groups was given by R p = k[styrene][BaSO 4 -Azo] where k is a constant, [styrene] is the styrene concentration, and [BaSO 4 -Azo] is the concentration of barium sulfate having azo groups. The result suggests that in such an initiating system the unimolecular termination of growing polymer radicals from the surface proceeds preferentially at the initial stage of the polymerization.

High density barium sulfate suspension for MRI: Optimization of concentration for bowel opacification

In this in vitro study of a potential oral MRI contrast agent, barium sulfate suspension (BSS), the object was to examine the effect of varying barium sulfate concentration on signal intensity while keeping suspension additives the same; and to optimize the concentration of a specific preparation of BSS. A phantom was used to test suspensions with concentrations of barium sulfate ranging from 90% to 220% w/v. T 1-weighted, T 2-weighted, and gradient echo sequences all showed a decrease in signal as concentration was increased to 170%. Between 170% and 220%, the signal intensity was constant on the T 1-weighted and T 2-weighted sequences. With the proton density and gradient echo sequences, there was a slower rate of decline in the signal intensity in the 170 to 220% range of BSS concentrations. We conclude that BSS with a concentration in the range of 170% to 220% w/v is optimum for the specific preparation used. We speculate that the behavior of the signal-to-noise ratio with changing concentration is explained by factors including proton density, T 1 relaxation enhancement, diffusion effects, and magnetic field inhomogeneity, depending on the particular pulse sequence used.

濃厚分散系の流動学的性質

Using an electrically-recording rotational rheometer, the rheological properties of suspensions of barium sulfate in nonpolar polyisobutylene were measured and compared with those of suspensions in polar linseed oil (thermally polymerized). Measurements of the flow properties at low rate of shear and of the dynamic viscosity and the dynamic modulus were made in the range of very low frequencies.In the former suspensions, with increase of concentration of barium sulfate, the yield value in steady-state flow and the dynamic viscosity and the dynamic modulus become larger, and the frequency-dispersion curve shifts to the lower frequency side. On the other hand, in the latter suspensions concentration dependence of those properties was not so significant.A minute addition of water to the former suspension increase the yield value and also the dynamic viscosity and the dynamic modolus. In the latter suspensions, there are almost no changes in the rheological properties on addition of water.Adsorption of sodium stearate on particles of barium sulfate gives reverse effects on the rheological properties.Anomalous plastic and anti-thixotropic behaviours were observed in the flow properties of the former suspensions.In concentrated suspensions, inter-particle interactions should be considered. A minute amount of substance adsorbed on the surface of particles may induce the coagulation of particles and build up a kind of structure in the system.

Formation and Aging of Precipitates. III. Electron Microscopic Studies on Barium Sulfate Precipitates in Aqueous Alcohol

Abstract 1. The solubilities of barium sulfate in aqueous alcohol were measured. 2. The barium sulfate particles precipitated in aqueous alcohol became smaller with the increasing concentration of alcohol; namely, with the decreasing solubility of barium sulfate. 3. In the case of the aqueous alcohol of the certain percentage (for a definite solubility of barium sulfate) the precipitated particles became larger with the decreasing total concentration of barium sulfate. 4. The barium sulfate precipitates prepared in the aqueous alcohol were practically diamond shaped; and spindle, hexagonal and sphere particles were also found. The shape of the precipitated particles seemed to depend on the induced period of the precipitation. 5. The electron micro-diffraction method was applied to analyze the crystal structure and, of course, the patterns obtained from various types of crystals agreed with those of barium sulfate.

Formation and Aging of Precipitates. I. Electron Microscopic Studies of the Formation of Barium Sulfate Precipitate

Abstract The shape and the size of barium sulfate precipitate prepared within the range of the total concentrations from 1.0000 to 0.0001 m were observed by an electron microscope. The particles were observed to precipitate in various forms (spherical, spindle, diamond and rectangular) in response to the total concentration of barium sulfate. It was confirmed that the precipitation law advocated by von Weimarn was still substantiated so far as the particles of the same shape were concerned.