Powder Dissolution Research Articles

Insight into Flufenamic Acid Cocrystal Dissolution in the Presence of a Polymer in Solution: from Single Crystal to Powder Dissolution.

Effects of three polymers, polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and copolymer of vinylpyrrolidone/vinyl acetate (PVP-VA), on the dissolution behavior of the cocrystals of flufenamic acid with theophylline (FFA-TP CO) and nicotinamide (FFA-NIC CO) were investigated at multiple length scales. At the molecular level, the interactions of crystal surfaces with a polymer were analyzed by observing etching pattern changes using atomic force microscopy. At the macroscopic scale, dissolution rates of particular faces of a single crystal were determined by measurement of the physical retreat velocities of the faces using optical light microscopy. In the bulk experiments, the FFA concentration in a dissolution medium in the absence or presence of a polymer was measured under both sink and nonsink conditions. It has been found that the dissolution mechanisms of FFA-TP CO are controlled by the defect sites of the crystal surface and by precipitation of the parent drug FFA as individual crystals in the bulk fluid. In contrast, the dissolution mechanisms of FFA-NIC CO are controlled by surface layer removal and by a surface precipitation mechanism, where the parent drug FFA precipitates directly onto the surface of the dissolving cocrystals. Through controlling the dissolution environment by predissolving a polymer, PVP or PVP-VA, which can interact with the crystal surface to alter its dissolution properties, improved solubility, and dissolution rates of FFA-TP CO and FFA-NIC CO have been demonstrated.

Performance comparison between crystalline and co-amorphous salts of indomethacin-lysine

The introduction of a highly water soluble amino acid as co-amorphous co-former has previously been shown to significantly improve the dissolution rate of poorly water soluble drugs. In this work, dry ball milling (DBM) and liquid assisted grinding (LAG) were used to prepare different physical forms of salts of indomethacin (IND) with the amino acid lysine (LYS), allowing the direct comparison of their solid-state properties to their in vitro performance. X-ray powder diffraction and Fourier-transformed infrared spectroscopy showed that DBM experiments led to the formation of a fully co-amorphous salt, while LAG resulted in a crystalline salt. Differential scanning calorimetry showed that the samples prepared by DBM had a single glass transition temperature (Tg) of approx. 100°C for the co-amorphous salt, while a new melting point (223°C) was obtained for the crystalline salt prepared by LAG. Intrinsic dissolution and powder dissolution studies demonstrated an increased dissolution rate of the drug in the co-amorphous salt compared to pure amorphous IND and also the crystalline drug-LYS salt. Furthermore, the co-amorphous IND-LYS salt presented long term physical stability in dry conditions at 25°C and 40°C. Overall, it has been shown that the co-amorphous form of a salt has a superior performance in comparison to a crystalline salt.

On the bubble-surfactant interaction

Surfactants play an important role in numerous chemical applications. Their effects on dispersion systems, as emulsions and colloids, are vastly studied. Yet, the dissolution (kinetics) of surfactants themselves has not received much scientific attention, despite the high implications for industrial applications. Nevertheless one can acknowledge the rapid growth of new technologies which are being considered to enhance various chemical processes, one being cavitation–the rapid growth and collapse of vapor bubbles, which results in the formation of shockwaves, streaming, free radicals, high local temperatures etc.In this paper, we investigate the influence of cavitation on the dissolution rate of Sodium Dodecyl Benzene Sulfonate. Using a high-speed camera, we determined the physics of the dissolution process. We have shown that the presence of cavitation greatly enhances the dissolution rate of surfactant in water through a process comparable to cavitation erosion.Finally, based on our findings, we also present the newly developed cavitation reactor, which could be potentially used for enhancing the process of washing powder dissolution in home appliances.

Fabrication and Compression Properties of Functionally Graded Copper Foam Made Using Friction Powder Sintering and Dissolution

Functionally graded (FG) metal foams have properties that vary with the position, giving them controlled compression deformation behavior with the desired plateau stresses. In this contribution, bilayer FG Cu foams consisting of a high-porosity layer and a low-porosity layer were fabricated and their compression properties were demonstrated. A friction powder sintering process based on the sintering and dissolution process was employed to fabricate the FG Cu foams. X-ray computed tomography observations revealed that the porosity markedly changed around the boundary between the layers of the FG Cu foam with NaCl volume fractions of V f = 80% (high porosity) and V f = 60% (low porosity), and the two layers exhibited almost constant porosities and were bonded seamlessly. From compression tests on the fabricated FG Cu foams, it was found that the V f = 80% layer first deformed while the V f = 60% layer hardly deformed at the beginning of the compression. Thereafter, the V f = 60% layer started to deform. From the compression stress–strain curves, the FG Cu foams exhibited two plateau regions with low and high plateau stresses corresponding to the deformation behavior. The first plateau stress and second plateau stress obtained from the FG Cu foams exhibited similar values to those obtained from uniform Cu foams with V f = 80% and V f = 60%, respectively. Moreover, Cu foams consisting of simply stacked uniform Cu foams with V f = 80% and V f = 60% without bonding exhibited almost the same deformation behavior and compression properties except for slightly larger dispersion than that in the FG Cu foams, which is considered to be due to the lack of bonding and the discontinuity between the pores at the boundary between the V f = 80% and V f = 60% layers.

Особенности растворения высокодисперсных порошков иридия в кислых средах

Особенности растворения высокодисперсных порошков иридия в кислых средах

Phosphor–silicone interaction effects in high power white light emitting diode packages

As a widespread application of high power phosphor-converted white light emitting diodes (pc-WLEDs) with long lifetime and color-consistence, the highly reliable phosphor/silicone composite, one of core materials used for light-conversion, working under severe operation conditions has become increasingly necessary. This paper selects three widely used monochromatic phosphors (Aluminates, Silicates and Nitrides based) as well as a pristine silicone to determine the potential interaction effects in their phosphor/silicone composites operated under different environments. Firstly, the transient thermal quenching and long-term high temperature ageing tests are used to investigate the thermal stabilities of both monochromatic phosphor powders and phosphor/silicone composites. Furthermore, the degradation mechanisms of phosphor/silicone composites aged under the high temperature & blue light exposure and high temperature & high humidity conditions are studied by considering the interaction effect. The results show that: (1) the thermal stabilities of different phosphors are different and the phosphor/silicone composites have more severe thermal quenching effects than those of their corresponding phosphor powders, but with the similar degradation trends; (2) the blue light irradiation can deteriorate silicone which is related to the photolysis effect; (3) the moisture can accelerate the degradation of phosphor/silicone composites because the change of pH condition, owing to the dissolution of phosphor powders in moisture, can degrade both phosphors and silicone.

Effect of cationic structure of ionic liquids on dissolution and regeneration of white hide powder

3-methyl-1-ethoxycarbonylimidazolium chloride ([EtMIM]Cl), was synthesized for white hide powder dissolution. White hide powder was successfully dissolved in [EtMIM]Cl, and regenerated from methanol. The dissolution data and thermodynamic parameter of white hide powder in [EtMIM]Cl and [BMIM]Cl were studied. Hydrogen bond basicity (β) and general polarizability (π*) of ILs were determined. The white hide powders were characterized by FT-IR, XRD, and TGA. The results showed that the maximum solubility of white hide powder in [EtMIM]Cl was higher than that in [BMIM]Cl at same dissolution temperature. At same temperature and same solid content, the dissolution time of white hide powder in [EtMIM]Cl was shorter than that in [BMIM]Cl. Density functional theory (DFT) simulation showed that two kinds of hydrogen bonds (C-H/O and C-H/Cl) and eight strong hydrogen bonds are found in [EtMIM]Cl/GPH, while seven hydrogen bonds are found in [BMIM]Cl/GPH. The carboxylic acid ester cationic group in [EtMIM]+ has more electronegative ester groups and stronger electronic cloud density oxygen atoms than alkyl group in [BMIM]+, [EtMIM]Cl is easier to destroy the intermolecular or intramolecular hydrogen bonds in white hide powder, so as to accelerate the dissolution of white hide powder in [EtMIM]Cl. The molecular simulation results indicated that both Cl− anions and [EtMIM]+ cation played important roles in the white hide powder dissolution.

Spinodal decomposition of tungsten-containing phases in functional coatings obtained via high-energy implantation processes

We have studied structural and phase transformations in tungsten-containing functional coatings of carbon steels obtained during the high-energy processes of implanting tungsten carbide micropowders by the method of complex pulse electromechanical processing and micropowders of tungsten by technology of directed energy of explosion based on the effect of superdeep penetration of solid particles (Usherenko effect). It has been shown that, during thermomechanical action, intensive steel austenization occurs in the deformation zone with the dissolution of tungsten carbide powder, the carbidization of tungsten powder, and the subsequent formation of composite gradient structures as a result of the decay of supercooled austenite supersaturated by tungsten according to the diffusion mechanism and the mechanism of spinodal decomposition. Separate zones of tungsten-containing phases of the alloy are in the liquid-phase state, as well as undergo spinodal decomposition with the formation of highly disperse carbide phases of globular morphology.

Dissolution and interaction of white hide powder in [Etmim][C12H25SO4

Ethyl chloroacetate, 1-methylimidazole and sodium dodecyl sulfate as raw materials, ester-functionalized surface active ionic liquid 3-methyl-(ethoxycarbonylmethyl)-imidazolium dodecylsulfate ([Etmim][C12H25SO4]) was synthesized for white hide powder dissolution. The structure of [Etmim][C12H25SO4] was ascertained by 1H NMR. The solubility of white hide powder in [Etmim][C12H25SO4] was measured from 60°C to 140°C with 20°C interval. Compared to [Etmim]Cl, [Etmim][C12H25SO4] was superior to dissolve white hide powder. The physicochemical performances of white hide powder/[Etmim][C12H25SO4] was measured by tensiometry, electrical conductivity and fluorimetry. The tensiometry results showed that the cmc of [Etmim][C12H25SO4] was 1.41mmol/L at 298.15K, indicating that [Etmim][C12H25SO4] exhibited higher surface activity than traditional anionic surfactants. The regenerated white hide powder was characterized by FT-IR, TGA, DSC, and XRD. Thermodynamics profiles demonstrated that the secondary structure of white hide powder was slightly destroyed during dissolution. The interaction mechanism between white hide powder and [Etmim][C12H25SO4] was studied by DFT computation using triple peptide Gly-Pro-Hyp (as GPHyp) as model. Seven hydrogen bonds were found between GPHyp and [Etmim][C12H25SO4]. The simulation results suggested that the formation of hydrogen bonds accelerated the dissolution of white hide powder in [Etmim][C12H25SO4].

Use of Triflic Acid in the Recycling of Thoria from Nuclear Fuel Production Scrap

The complexity in the dissolution of thoria (ThO2) and thorium-based fuels at an industrial scale is one of the limiting factors for the implementation of the thorium fuel cycle. In this study, we investigated the dissolution of unirradiated thoria powder, simulating thoria from nuclear fuel production scrap, in trifluoromethanesulfonic acid (triflic acid) solutions. The dissolution method was compared with the standard thorium uranium extraction (THOREX) dissolution process. The viability of the conversion of thorium(IV) triflate into thoria via oxalic acid precipitation and calcination was demonstrated, and the obtained thorium(IV) oxalate intermediate was characterized. Spent triflic acid could be recycled and reused for dissolution of a new batch of thoria. A triflic acid-based route could hence be considered a viable alternative for the standard THOREX-reagent-based process.

Modulating the Dissolution and Mechanical Properties of Resveratrol by Cocrystallization

Resveratrol (RSV), a dietary polyphenol found in red wine, has renewed interest in recent years due to a broad range of in vitro evidence that indicate cardioprotective effects. Herein, we have synthesized four RSV cocrystals with the objective to improve the physicochemical and mechanical properties. Single crystal structures were illustrated and comprehensive characterization of the cocrystals were performed. In addition, powder dissolution of RSV cocrystals in different buffer medium containing different surfactants were conducted, and the result revealed that PVP K30 is an effective surfactant to maintain the supersaturation. Then pharmacokinetic experiments suggested that RSV cocrystals showed shorter Tmax, and RSV–NA exhibited higher Cmax and AUC0–24 values. Furthermore, RSV cocrystals exhibited superior mechanical properties compared to RSV pure component. These results may provide an alternative formulation for RSV.

Ammonio methacrylate copolymer as a carrier for water-insoluble drug, preparation and characterization of an oral controlled-release matrix tablet

The use of ammonia methacrylate copolymer as a carrier for the preparation of oral controlled-release matrix tablets containing water-insoluble drugs and investigating the effect of curing conditions. Tablets were cured at 40 °C with or without 75% relative humidity (RH). The crystalline structures were analyzed with powder X-ray diffractometry and dissolution studies were performed in USP dissolution apparatus type II. With increasing the ethanol content (0–20%, w/w) in the granulation fluid, the drug release was decreased. The drug release from the tablets cured at 70 °C/24 h was similar to those that cured at 40 °C with 75% RH/24 and the drug release kinetic was fitted with the zero-order release mechanism. The x-ray study showed no change in the crystalline structure of carbamazepine. As the curing duration, compression force and granule size were increased, the drug release was decreased. The drug release was proportionally changed with surface area/volume ratio, agitation rate, and polymer permeability; meanwhile, the release was unchanged with increased drug content from 30% to 50% w/w. Ammonio methacrylate copolymer could be used as a carrier for water-insoluble drugs and to prepare controlled-release matrix tablets.

Controlled Suspensions Enable Rapid Determinations of Intrinsic Dissolution Rate and Apparent Solubility of Poorly Water-Soluble Compounds

PurposeTo develop a small-scale set-up to rapidly and accurately determine the intrinsic dissolution rate (IDR) and apparent solubility of poorly water-soluble compounds.MethodsThe IDR and apparent solubility (Sapp) were measured in fasted state simulated intestinal fluid (FaSSIF) for six model compounds using wet-milled controlled suspensions (1.0% (w/w) PVP and 0.2% (w/w) SDS) and the μDISS Profiler. Particle size distribution was measured using a Zetasizer and the total surface area was calculated making use of the density of the compound. Powder and disc dissolution were performed and compared to the IDR of the controlled suspensions.ResultsThe IDR values obtained from the controlled suspensions were in excellent agreement with IDR from disc measurements. The method used low amount of compound (μg-scale) and the experiments were completed within a few minutes. The IDR values ranged from 0.2–70.6 μg/min/cm2 and the IDR/Sapp ratio ranged from 0.015 to 0.23. This ratio was used to indicate particle size sensitivity on intestinal concentrations reached for poorly water-soluble compounds.ConclusionsThe established method is a new, desirable tool that provides the means for rapid and highly accurate measurements of the IDR and apparent solubility in biorelevant dissolution media. The IDR/Sapp is proposed as a measure of particle size sensitivity when significant solubilization may occur.

A portable RGB sensing gadget for sensitive detection of Hg2+ using cysteamine-capped QDs as fluorescence probe

A facile one-pot method was proposed to synthesis cysteamine capped CdTe QDs with a high quantum yield 30%. In the synthesis process, nitrogen protection, ultrasonic treatment, and light irradiation were unnecessary. Additionally, potassium tellurite was used instead of Te powder as Te source, avoiding of the time-consuming Te powder dissolution process. The prepared QDs were found to be Hg2+ sensitive. The detection linear range for Hg2+ was from 5 to 300nM, and the detection limit was calculated to be 1nM. The detection mechanism was mainly ascribed to the electron transfer from cysteamine capped QDs to Hg2+, resulting in a fluorescence quenching phenomenon. In addition, we developed a portable RGB sensing gadget with the QDs as fluorescence probe for Hg2+ detection, and the linear range was from 5 to 200nM. Furthermore, the gadget was applied for Hg2+ detection in tap water sample. The results showed that the average recoveries in real tap water sample were in the range from 97.2% to 115.3%, which indicated that accuracy and precision were satisfactory for practical application requirements.

The effects of processing parameters on the properties of micro-scale porous surface for a micro-channel reactor

To improve the performance of hydrogen production via a microchannel reactor with a porous surface, the process of layered powder sintering and dissolution method is optimized, and the effects of processing parameters on the morphological and mechanical properties of the porous surface structure are studied. Based on the preliminary experiments, three key parameters in the process are the size of the NaCl particle, the compaction pressure, and the sintering temperature. Besides, the porous surface structures are evaluated by the specific surface area and compression strength to optimize the influencing variables. Results show that the specific surface area of porous surface structure is determined mainly by the size of NaCl particle, while the pressure and temperature have little influence unexpectedly within the range of experimental condition. With the increase of temperature and pressure, the compression strength will be enhanced, but the increase of the size of NaCl particles will cause the decrease of compression strength. The optimum compaction pressure, sintering temperature, and size of the NaCl particle are obtained respectively. Finally, the optimum parameters have been used to manufacture the micro-channel catalyst support with a porous surface, and its hydrogen production can be maximumly enhanced by 90% compared with the surface fabricated with NaCl particles of 125–150 µm.

Effects of calcium chelating agents on the solubility of milk protein concentrate

The aim of this study was to determine the effects of calcium chelating agents on the dissolution and functionality of 10% (w/w) milk protein concentrate (MPC) powder. MPC powder dissolution rate and solubility significantly (P > 0.05) increased with addition of sodium phosphate, trisodium citrate (TSC) and sodium hexametaphosphate (SHMP), compared to MPC dispersions alone. Trisodium citrate and SHMP addition increased viscosity as a result of micelle swelling. However, dispersions containing SHMP showed a decrease in viscosity after prolonged time due to micelle dissociation. Overall, MPC powder dissolution was aided by the addition of calcium chelating agents.

Characterization and Leaching of Neodymium Magnet Waste and Solvent Extraction of the Rare-Earth Elements Using TODGA

The rare-earth elements (REEs) are considered as some of the most critical elements in the EU and the USA today. E-scrap, such as end-of-life neodymium magnets, could be a viable secondary source for the recovery of these elements. Neodymium magnets (NdFeB) consist of considerable amounts of Nd, Dy, Pr, and some other REEs, depending on the specific application. Apart from REEs, neodymium magnets are made up of around 60% iron, which can pose a challenge in their recycling. For example, iron can be dissolved along with other elements during leaching or co-extracted during solvent extraction. In this work, extraction of REEs with TODGA (tetraoctyl-diglycolamide) from a real leachate, obtained by neodymium magnet powder dissolution in nitric acid, was studied. The goal was to selectively extract the REEs from other elements in the solution. TODGA was used as the extracting agent due to its selective extraction properties for REEs and other f-block elements. The influence of the diluent on the overall extraction and the selectivity of the extraction was studied in order to determine application feasibility of future processes. To this end, experiments using Solvent 70 (hydrocarbons C11–C14, ≤0.5 wt% aromatics), hexane, toluene, cyclohexanone and 1-octanol as the diluents were performed. TODGA has shown good selectivity between REEs and other elements in solution under almost all conditions, reaching the highest distribution ratios of REEs in the aliphatic diluents, while the distribution ratios of other non-REEs reach a mere value of 0.1. An exception was cyclohexanone, which has the ability to extract small amounts of ions itself. The highest separation factors between Dy and the light REEs (Nd and Pr) were observed with a 0.01 M solution of TODGA in Solvent 70. REEs, as group, were extracted with 0.1 M solutions of TODGA in all diluents except for cyclohexanone, which led to extraction of Al and B at amounts greater than 10%. Stripping with over 98% efficiency was achieved using MQ water in one step.

Dissolution behavior of CaO-MgO-SiO2-based bioceramic powders in simulated physiological environments

Abstract In this study, the dissolution behavior of CaO-MgO-SiO 2 -based bioceramics was investigated in vitro by using a stage-by-stage simulating physiological environment method. Preliminary dissolution rules of CaO-MgO-SiO 2 -based bioceramics are presented by soaking akermanite, bredigite, and diopside powders in saline solution. Dissolved Ca and Mg ion concentrations were proportional to the chemical composition of the bioceramics, while the dissolution of Si ion was more affected by their crystal structure. The analysis of zeta potential indicated that ions (possibly including both the dissolved and intrinsic ions) would be adsorbed on the surface of bioceramic powders during soaking in saline solution. Further studies of the dissolution of akermanite powder was performed using different solid-liquid ratios in simulated body fluid (SBF) and α-MEM culture medium. It was found that hydroxyapatite was formed on the surface of akermanite in SBF and amino-containing compounds attracted to the surface of the powders in α-MEM culture medium would impede the diffusion of ions to delay ions release and weaken hydroxyapatite formation. When akermanite powders were co-cultured with BMSCs, HUVECs, or L929 cells, the concentrations of Ca, Mg and Si ions in the solution were lower than that in cell-free medium. Additionally, the pH value gradually decreased with soaking time, unlike what occurs when the materials are soaked in cell-free media, suggesting effects due to the cellular intake of related ions and the release of acidic cellular metabolites. The akermanite extracts in a certain concentration range could promote cell proliferation via cellular intake of related ions. In turn, this ion consumption would affect the dissolution behavior of bioceramics in simulated physiological environments.

Cocrystals of Baicalein with Higher Solubility and Enhanced Bioavailability

Baicalein (Bai) is one of the most important bioactive flavonoids isolated from the well-known traditional Chinese medicine called “Huang Qin”. Though it has broad therapeutic capability, the bioavailability is limited due to its poor solubility. In this study, we aimed to modulate its solubility through cocrystallization. Cocrystals of Bai with isoniazide (Inia), isonicotinamide (Inam), caffeine (Caf), and theophylline (Tph) were obtained. And different cocrystallization methods lead to different cocrystal phases for Inam and Tph. These cocrystals were characterized using powder X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, dynamic vapor sorption, and Fourier transform infrared spectroscopy. Among all the cocrystals studied, BaiCaf is found to be superior in powder dissolution and pharmacokinetic behavior. Area under the curve values of BaiCaf is improved by a factor of 4.1, and the bioavailability of baicalein is thus expected to be accordingly increased. Given that C...

Crystal characterization and transformation of the forms I and II of anticoagulant drug rivaroxaban

The crystal forms I and II of rivaroxaban were characterized by powder X‐ray diffraction (PXRD), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. Powder dissolution testing was carried out at 310.15 K in the dissolution media at pH = 1.0 and pH = 6.8, respectively. The solution‐mediated phase transformation from form II to form I was investigated under different temperature, slurry density and stirring speed, respectively, by use of the FTIR spectroscopy. The results showed that, the two forms were monotropically‐related, and in the both dissolution media the concentration of form II was obviously higher than that of form I at the same time which demonstrated that form II was the metastable form. Among the evaluated solid‐state kinetic models the Prout‐Tompkins and Avrami‐Erofeev (n = 3) equations gave a satisfactory correlation of the phase transformation process from form II to form I. The activation energy of phase transformation was calculated as 19.151 kJ·mol−1 by means of Arrhenius analysis. In addition, the phase transformation rate increased with increasing temperature, slurry density and stirring speed.