Size Of Precipitated Particles Research Articles

Calcium Chloride in Neonatal Parenteral Nutrition: Compatibility Studies Using Laser Methodology

IntroductionWe have previously reported results of precipitation studies for neonatal parenteral nutrition solutions containing calcium chloride and sodium phosphate using visual methods to determine compatibility. The purpose of this study was to do further testing of compatibility for solutions containing calcium chloride using more sensitive methods.MethodsSolutions of Trophamine (Braun Medical Inc, Irvine, CA) and Premasol (Baxter Pharmaceuticals, Deerfield, IL) were compounded with calcium chloride and potassium phosphate. Controls contained no calcium or phosphate. After incubation at 37° for 24 hours solutions without visual precipitation were analyzed to determine mean particle size using dynamic light scattering from a laser light source.ResultsParticle sizes were similar for control solutions and those without visual precipitation and a mean particle size <1000 nm. Compatible solutions were defined as those with added calcium and phosphate with no visual evidence of precipitation and mean particle size <1000 nm. In solutions containing 2.5–3% amino acids and 10 mmol/L of calcium chloride the maximum amount of potassium phosphate that was compatible was 7.5 mmol/L.ConclusionMaximum amounts of phosphate that could be added to parenteral nutrition solutions containing Trophamine and calcium chloride were about 7.5–10 mmol/L less for a given concentration of calcium based upon laser methodology compared to visual techniques to determine compatibility. There were minor differences in compatibility when adding calcium chloride and potassium phosphate to Premasol versus Trophamine.

Removal of As(III) and As(V) by ferric salts coagulation – Implications of particle size and zeta potential of precipitates

This study investigates the removal of As(III) and As(V) by ferric salts coagulation under solution chemistry influences with particular emphasis on the role of zeta potential and size of the precipitates. The results indicate that As(III) removal efficiency increased with increase of solution pH, but there was almost no correlation with zeta potential of the precipitates. In contrast, the highest As(V) removal occurred in the pH range of positive zeta potentials and the removal efficiencies declined significantly as the precipitates became more negatively charged at high pH values. The relative importance of the two coagulation removal mechanisms, co-precipitation and adsorption, was found to be dependent on the solution pH. The sizes of the early-formed precipitates were in the colloidal range, with the largest size being at the isoelectric point (IEP). Precipitate sizes affected the residual Fe level at certain pH values after microfiltration and sand filtration, but showed much less effect on the arsenic removal. Electrolyte concentrations showed a noticeable effect on the precipitate size, but only a small effect on the arsenic removal. Humic acid exhibited profound influences both on zeta potential, size of the precipitates and arsenic removal.

Preparation and characterization of azithromycin nanodrug using solvent/antisolvent method

Nanoparticles of azithromycin are prepared using solvent/antisolvent precipitation method. The solubility of drug in water and the oral bioavailability are increased with decreasing particle size. The effect of type and concentration of surfactant and feed drug concentration are evaluated on the precipitated particle size. The nano-azithromycin in range 200–400 nm is obtained by the addition of absolute ethanol as solvent, water as antisolvent in presence of Tween® 80 as surfactant. The prepared nanoparticles are characterized by infra-red spectra, particle size distribution, scanning electron microscopy, X-ray diffraction and differential scanning calorimetry. The chemical structure of nanosized azithromycin does not show any change but the crystallinity reduces in comparison with raw drug. Dissolution of azithromycin nanoparticles in purified water and buffer phosphate (pH of 6.0) is 2.93 and 3.36, respectively, times of raw drug in 30 min.

Precipitation Simulation of AZ91 Alloy

Precipitation simulation of AZ91 (Mg-9Al-1Zn; all compositions are in wt.% unless otherwise stated.) magnesium alloy is carried out in this work using the PanPrecipitation module of Pandat™ software. In addition to the software, the thermodynamic database, mobility database, and precipitation database for AZ91 were developed to perform the simulation. The simulated results, such as the number density and particle size of the γ-Mg17Al12 precipitate, showed good agreement with the experimental data. Moreover, the simulated results were then used as input for the prediction of yield strength and micro-hardness of AZ91 aged at different temperatures, which also agreed well with experimental results. To demonstrate the applicability of the databases developed for AZ91, simulations were also carried out for two compositions with lower and higher Zn content. The simulated hardness showed reasonable agreement with the published experimental data.

Effects of expansion parameters on characteristics of gemfibrozil powder produced by rapid expansion of supercritical solution process

Micronization of gemfibrozil particles was carried out by the rapid expansion of a supercritical solution process with CO2 as the solvent. In this work, effects of spray distance (2.5, 5.5, 10.5 and 15cm), nozzle type (capillary and orifice nozzles), nozzle diameter (0.25 and 0.5cm for orifice diameter) and temperature of expansion vessel (10, 26, 30 and 65°C) on the characteristics of gemfibrozil particles were studied. In addition to traditional sampling methods, an electrostatic precipitation was also carried out as sampling method for collection of the RESS produced particles. Based on our knowledge, this study on the effect of charged plate sampling method (electrostatic sampler) in the RESS process is the first study of this kind. The smallest mean size of gemfibrozil particles produced by orifice nozzle with 0.25mm inner diameter, 10.5cm spray distance and 65°C temperature of expansion vessel was about 0.6μm. The largest mean particle size of gemfibrozil particles was 2.1μm produced by a capillary nozzle with a spray distance of 5.5cm. The results showed that the spray distance and the nozzle type were the efficient parameters on the morphology of precipitated particles but nozzle diameter had little effect on the mean size of precipitated particles.

Elevated Small Dense Low-Density Lipoprotein Cholesterol as a Predictor for Future Cardiovascular Events in Patients with Stable Coronary Artery Disease

The aim of the present study was to investigate how small dense low-density lipoprotein cholesterol (sdLDL-C) compared with LDL-C affect the long-term prognosis in patients with stable coronary artery disease (CAD). sdLDL-C measured by heparin magnesium precipitation and LDL particle size measured by non-denatured gradient-gel electrophoresis were compared in 190 consecutive CAD patients who underwent coronary arteriography between 2003 and 2004 who did or did not develop cardiovascular events during a seven-year follow-up period. Cardiovascular events were death caused by cardiovascular diseases(CVDs), onset of acute coronary syndrome, need for coronary and peripheral arterial revascularization, hospitalization for heart failure, surgical procedure for any CVDs, and/or hospitalization for stroke. First-time cardiovascular events were observed in 72 patients. Those who experienced cardiovascular events were older and had higher prevalence rates of hypertension and diabetes; significantly higher Gensini coronary atherosclerotic scores; significantly higher levels of sdLDL-C, sdLDL-C/LDL-C, and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratios; and greater glycated hemoglobin(Hb)A1c and brain natriuretic peptide (BNP) levels. They also had significantly smaller LDL particle sizes, HDL-C, apolipoprotein A-1, and estimated glomerular filtration rate (GFR) compared with patients without cardiovascular events. Conversely, LDL-C, non-HDL-C, apolipoprotein B, remnantlike particle cholesterol, and high-sensitivity C-reactive protein (hs-CRP) levels were similar between the two groups. A Kaplan-Meyer event-free survival curve demonstrated that patients with sdLDL-C≥35 mg/dL (median level) had significantly poorer prognosis compared with those with lower sdLDL-C levels, while patients with LDL-C ≥100 mg/dL had a non-significantly lower survival rate. These results confirm that sdLDL-C is a very promising biomarker to predict future cardiovascular events in the secondary prevention of stable CAD.

Manipulation of key parameters in RESS process for attapulgite particles utilizing in drilling mud and investigation on its rheological characteristics

Abstract The crucial role of drilling mud in the petroleum industry could be considered as a stimulus force to conduct profound investigation on this issue. Drilling mud can be composed of various types of clay. All the clays have their unique properties and when prepared with water, they will exhibit different viscosities, gel strengths, and most importantly, the rheological characteristics. Attapulgite clay for drilling is also known as salt water clay which does not show any significant signs of swelling. This paper presents an evaluation of the most significant parameters in the rapid expansion of supercritical solutions (RESS) process on the size and morphology of the precipitated attapulgite particles based on the Taguchi method and also investigates the rheological characteristics of drilling mud. The average particle size of unprocessed attapulgite particles was about 15 µm, while the average particle size of the ultrafine precipitated attapulgite particles was between 0.1 µm and 1.35 µm based on different experimental conditions. Regarding the rheological characteristics, findings indicate that the attapulgite particle size distribution affects yield point (YP), while it does not affect plastic viscosity (PV). This means that an excellent achievement in order to improve the carrying capacity of drilling mud during drilling operations is obtained.

Technology of phosphorus slag processing for preparation of precipitated silica

The article presents the results of studying the determination of the influence of the nature of a number of mineral reagents (solutions of hydrochloric, nitric, sulfur and phosphoric acids, as well as sodium hydroxide and carbonate) on silicon extraction in solution upon he leaching of phosphorus production slags. The results of studying the process of the breakdown of phosphorus production slag with sodium carbonate solutions depending on various physicochemical parameters are provided. The optimum conditions of main technological operations were found and the main parameters that influence the morphological structure and size of precipitated silica particles were established. The influence of the conditions of washing of carbonate-silicate cake on its chemical, phase, and granulometric composition has been studied. Scaled-up laboratory tests have been carried out and a technology for processing phosphorus production slags to produce mineral fillers was developed on their basis. Conclusions on the applicability of pilot batches of white soot in tire and paint industries and carbonate-silicate fillers in construction industry and agriculture were obtained.

Effect of ammonium nitrate on precipitation of Ammonium Di-Uranate (ADU) and its characteristics

Scanning Electron Microscopic (SEM) images of ADU prepared with gaseous ammonia, (a) in presence of excess ammonium nitrate (80 g/L) as well as (b) in absence of excess ammonium nitrate at different magnification. Effect of ammonium nitrate on precipitation of Ammonium Di-Uranate (ADU) from nitric acid medium via gaseous ammonia route had been investigated. Studies on effect of ammonium nitrate on precipitation time, particle size, shape, surface morphology , flowability , oxygen/uranium (O/U) ratio and tap density of calcined ADU were carried out at various ammonium nitrate concentrations. It was observed that, the presence of excess ammonium nitrate influences the precipitation time, particle size distribution and surface morphology of the ADU. ADU and uranium oxide were characterized with Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD). Presence of ammonium nitrate during precipitation leads to the formation of bigger, porous and uniform particles as compared to the ADU prepared without ammonium nitrate additions.

Interaction of Sr(II) and Np(V) with potassium ferrate(VI) reduction products in aqueous solution

The interaction of Sr(II) and Np(V) with potassium ferrate(VI) reduction products in aqueous solution at pH 4–8 was studied by liquid scintillation spectrometry. The ferrihydrite precipitate formed by reduction of ferrate ions quantitatively sorbs Sr(II) and Np(V) from 0.1 M NaClO4. The precipitate particle size determined by scanning electron microscopy is in the nanometer range. The degree of recovery of the radionuclides from simulated liquid radioactive wastes containing such complexing agents as acetate, citrate, and nitrate ions is 70 ± 5 and 84 ± 2%, respectively.

Counter-current extraction and separation of U(VI) from a mixture of U(VI)–Th(IV)–Y(III) using tris-2-ethyl hexyl phosphate (TEHP)

Evaluation of tris-2-ethyl hexyl phosphate (TEHP) for counter-current extraction and separation of U(VI) from a mixture of U(VI)–Th(IV)–Y(III) from nitric acid medium was carried out under wide experimental conditions. Batch extraction studies were carried out to investigate the effect of nitric acid concentration in feed solution, U(VI)/Th(IV) ratio and extractant concentration and the results were compared with established solvent such as tri-n-butyl phosphate (TBP) for separation of U(VI) from nitric acid medium. McCabe–Thiele diagrams for extraction as well as stripping of U(VI) were constructed under simulated conditions. Based on batch experiments, six stage counter-current extraction studies were conducted under various TEHP concentration and it was observed that 0.1 M TEHP/n-paraffin was most suitable for selective recovery of U(VI) from a mixture of U(VI)–Th(IV). An optimized condition, 0.1 M TEHP/n-paraffin, 2 M HNO3 in feed and six number of stages was evaluated for selective extraction and stripping of U(VI) from a solution containing mixture of U(VI)–Th(IV)–Y(III) in nitric acid medium. The U(VI) in strip solution was precipitated using 30 % H2O2 at pH ~3. Average particle size of the final precipitate was found to be ~33 μm.

Characterization of the microstructures and mechanical properties of 25CrMo48V martensitic steel tempered at different times

The microstructures of 25CrMo48V martensitic steel quenched (Q) at 900°C and tempered (T) at 650°C for 5–105min were characterized by transmission electron microscope (TEM). The tensile and impact properties were evaluated from the Q–T treated samples. The results indicate that the precipitate size is increased with the prolonged soaking time and the dependence of volume fraction of precipitated particles on the tempering time follows the classical Johnson–Mehl–Avrami (JMA) model. The refinement precipitated particle could induce the enhancement of yield strength. The dependence of the yield strength of 25CrMo48V martensitic steel tempered at 650°C for different times on the lath width and the precipitated particle size can be described as σy=645+145w−1+1.27×10−17Dp−13.

Process variables in the formation of nanoparticles of megestrol acetate through rapid expansion of supercritical CO2

Submicron particles of megestrol acetate (MA) were precipitated by rapid expansion of supercritical solution (RESS) method, using CO2 as supercritical solvent in the presence of menthol as solid co-solvent. The effects of extraction temperature, extraction pressure and weight fraction of menthol on the mean particle size of precipitated particles were investigated using full factorial design. The experiments were carried out at three temperature levels from 40 to 60°C, three pressure levels from 15 to 25MPa, and 2 to 6wt.% of co-solvent. Megestrol acetate nanoparticles were formed with mean particle sizes between 102.8 and 516.3nm and statistical analysis showed that pressure had the most considerable effect on the size of nanoparticles. Increasing the temperature and pressure, and decreasing the amount of solid co-solvent resulted in the formation of finer particles.

Precipitation of AlN and MnS in Low Carbon Aluminium-Killed Steel

The precipitation kinetics of AlN and MnS in low carbon aluminium-killed steel was calculated. Transmission electron microscopy (TEM), energy disperse spectroscopy (EDS) and phase analyses have been used to investigate the morphology, compositions and particle size distribution of AlN and MnS precipitates in three positions of the coil. The particles of AlN and MnS precipitates in the ferrite region after coiling and distributes along and adjacent to the ferrite grain boundaries. The shapes of AlN are plate-like, the precipitates size is about 10 to 60 nm; the shapes of MnS are spherical, the precipitates size is about 200 to 600 nm. The precipitation behavior of AlN is sensitive to the isothermal temperature and holding time, the precipitation quantity and particle size distribution of AlN in different positions of coil are unequal.

EFFECT OF CONTROLLED ROLLING PROCESSING ON NANOMETER-SIZED CARBONITRIDE OF Ti-Mo FERRITE MATRIX MICROALLOYED STEEL

Single nanometer-sized particles, which are smaller than 10 nm, can significantly en- hance the precipitation strengthening in microalloyed steels, thus causing their strength to be promoted greatly. In order to improve the strength of the steel, it is quite necessary to get a large amount of single nanometer-sized particles through optimizing rolling technology. In this work, the effects of two different kinds of controlled rolling technologies on the size and distribution of precipitated particles in the Ti-Mo ferritie matrix microalloyed steel have been researched using SEM, TEM and small-angle X-ray scattering. The results show that with the same total rolling reduction, the steel rolled only in phase crystallization zone can obtain a higher portion of single nanometer-sized particles than that rolled respectively in phase recrystallization and nonrecrystallization zones, in which those single nanometer-sized particles account for about 75% (mass fraction) of whole precipitated particles. In order to study the effect of deformation potency in phase zone on the amount of precipitates in phase and the micro-crystal size, nucleation rate and incubation time of following precipitates in ! � transformation and ferritie matrix after ! � transformation, some thermodynamics and kinetics calculations and analysis on precipitation are also conducted.

우라늄 오염 동전기 침출액의 재이용을 위한 침전-여과 방법

우라늄 오염토양을 동전기제염 시 많은 양의 동전기 침출액이 발생한다. 발생된 우라늄 침출액을 재이용하기 위한 처리기술이 개발되었다. 동전기제염 시 발생된 우라늄침출액 내의 우라늄농도는 180 ppm이었고, Mg(II), K(I), Fe(II), Al(III) 농도는 20 ppm~1,210 ppm이었다. 우라늄침출액의 최적 처리공정은 혼합, 응집, 침전, 농축, 그리고 여과로 구성된다. 침전액의 pH를 11로 맞추기 위해, calcium hydroxide는 3.0g/100ml 그리고 sodium hydroxide는 2.7g/100ml이 필요했다. 여러 침전실험 결과 NaOH+0.2g alum+0.15g magnetite가 여과를 위한 최적 침전혼합제로 선정되었다. NaOH+0.2g alum+0.15g magnetite 투입 시 침전입자의 평균크기는 <TEX>$600\;{\mu}m$</TEX>이었다. pH=9에서 침전 후 상등액에 총 금속농도가 가장 낮았기 때문에, 최적 침전을 위하여 먼저 0.2g/100ml alum와 0.15g/100ml magnetite 투입한 후 pH=9일 때까지 sodium hydroxide을 투입하여야 한다. A large volume of uranium electrokinetic leachate has been generated during the electrokinetic decontamination to remove uranium from contaminated soil. The treatment technology for the reuse of the uranium leachate was developed. The concentration of uranium in the generated uranium leachate was 180 ppm and concentrations of Mg(II), K(I), Fe(II), and Al(III) ions ranged from 20 ppm to 1,210 ppm. The treatment process for uranium leachate consisted mainly of mixing and cohesion, precipitation, concentration, and filtration. In order to obtain the pH=11 of a precipitate solution, the calcium hydroxide needs to be 3.0g/100ml and the sodium hydroxide needed to be 2.7g/100ml. The results of several precipitation experiments showed that a mixture of NaOH+0.2g alum+0.15g magnetite was an optimal precipitant for filtration. The average particle size of precipitate with NaOH+alum+0.15g magnetite was <TEX>$600\;{\mu}m$</TEX>. Because the total value of metal concentrations in supernatant at pH=9 was the smallest, sodium hydroxide should be added with 0.2g alum and 0.15g magnetite for pH=9 of leachate.

The development of precipitation-filtering technology for uranium electrokinetic leachate

A great volume of uranium electrokinetic leachate has been generated during the operation of the electrokinetic decontamination experiment to remove uranium from radioactive soil. Treatment technology for the reuse of the generated uranium leachate was developed. The concentration of uranium in the generated uranium leachate was 180 ppm and concentrations of Mg(II), K(I), Fe(II), and Al(III) ions were high. When sodium hydroxide was put in the uranium leachate as a precipitant, the precipitation velocity was shorter and the precipitate particle size was larger than those of calcium hydroxide. The treatment process for uranium leachate consists mainly of mixing and cohesion, precipitation, concentration, and filtration. In order for the pH of a precipitate solution to reach 11, the amount of sodium hydroxide and calcium hydroxide needs to be 2.7–3.0 g/100 ml. In several respects, sodium hydroxide is more efficient as a precipitant than ammonium hydroxide and calcium hydroxide. The results of precipitation experiments show that a mixture of NaOH + 0.2 g alum + 0.15 g magnetite is an optimal precipitant for filtration. The average particle size of precipitate with NaOH + alum + 0.15 g magnetite was 600 μm. Because a pH level of 9 provides the lowest total amount of metal concentrations in the supernatant, sodium hydroxide should be added to 0.2 g alum and 0.15 g magnetite for optimal filtration until the pH of the leachate reaches 9.

Ti-Mo FERRITE MATRIX MICRO-ALLOY STEEL WITH NANOMETER-SIZED PRECIPITATES

The morphology, size, distribution and types of precipitate particles were studied by using OM, SEM, TEM, EDS and SAEDP for Ti-Mo low-carbon ferrite matrix micro-alloy steel with four different titanium contents. Experimental results indicated that there were two kinds of particles with obvious different sizes in ferrite matrix, one was nanometer sized particles, which were smaller than 10 nm, the composition of these particles was compound carbonitride of Ti and Mo. These particles precipitated in chains or dispersed in the interior of grains. Dislocation nodes and the dislocation network were preferential nucleation sites for these particles. Another kind of particles was titanium carbonitride larger particles with a cap and few in number in ferrite matrix. Their size was about 200 to 300 nm and morphology was square. Tensile experimental results at room temperature and high temperatures showed that ferrite matrix micro-alloy steel with nanometer sized had good mechanical properties. No.4 steel had good performance at 600 with a yield strength of about 300 MPa.

Investigation of Ti inclusions in wire cord steel

Ti content in specimens of 80 grade wire cord steel was measured by laser ablation inductively coupled plasma mass spectrometry. It was found that the average Ti content increased and then decreased during electrical arc furnace (EAF) tapping→refining→continuous casting. Under current control condition of 80 grade wire cord steel in Nanjing Iron and Steel United Co. Ltd (NISUCL), the calculation results in several aspects such as formation thermodynamics, solidification segregation and growth kinetics of TiN particles showed that the formation of TiN only took place in the two‐phase region where the solidification ratio is greater than 98%, or in solid phase region; both solidification segregation of Ti and N increased with increasing cooling rate and the segregation tendency was greater with increasing solidification fraction. The greater the cooling rate during solidification, the smaller the size of precipitated TiN particles. The size of precipitated TiN particles is 3–7 μm, which accorded with the size measured in metallographic image of TiN inclusions found in wire rod specimens.

Preparation of porous particles by liquid–liquid interfacial crystallization

Liquid–liquid interfacial crystallization was proposed as a novel method of controlling crystal shape and size of precipitated solute particles. The crystallization was performed at interface forming two separate phases of aqueous solution and organic solvent in the present study, and progressed by increase of supersaturation caused by the slightly mutual diffusion at the liquid–liquid system. This crystallization process is possible to precipitate particles at room and constant temperature without cooling or heating sources. The liquid–liquid interfacial crystallization method was able to carry out in changing the shape of the interface. A spherical shape was made by droplets in the present liquid atomization process. Crystallization started when the droplets of the solution sprayed into the organic liquid. Our research involved producing glycine porous particles by atomizing glycine solution into 1-butanol and other organic solvent with 3-fluid nozzle. The collision between the solutions in compressed air produced the micro-size droplets of glycine solution. In using 1-butanol liquid, the glycine crystallized at the glycine solution/1-butanol interface. The spherical aggregated particles were obtained in this spray granulation process. In addition, the transformation occurred from unstable β-structure to metastable α-structure with changing crystallization condition, and it was found that α- and β-structure of glycine coexist in the obtained particles from observation by X-ray powder diffraction.