Highly conductive pristine graphene electrodes were fabricated by inkjet printing using ethyl cellulose-stabilized ink prepared from pristine graphene. Pristine graphene was generated by exfoliation from graphite using ultrasound-assisted supercritical CO2. The ink, at concentrations up to 1 mg/mL, was stable for more than 9 months and had compatible fluidic characteristics for efficient and reliable inkjet printing. The inkjet printing patterns of the graphene on diverse substrates were uniform and continuous. After 30 printing passes and annealing at 300 °C for 30 min, the printed films developed a high conductivity of 9.24 × 103 S/m. The resistivity of the printed electrodes on the flexible substrates increased by less than 5% after 1000 bending cycles and by 5.3% under a folding angle of 180°. The presented exfoliated pristine graphene and the corresponding efficient methods for formulating the ink and fabricating conductive electrodes are expected to have high potential in applications involving graphene-based flexible electronic devices.

Highly flexible transparent conductive films with a sandwich structure consisted of graphene/silver nanowires (AgNWs)/graphene (GAG) were fabricated by a facile method of combining vacuum filtration with acetone vapor treatment. This approach involves two processes: the vacuum filtration of the dispersion solution of the graphene, the AgNWs, and the graphene in turn through a porous mixed cellulose esters membrane (MCEM); the treatment of MCEM using acetone vapor to form a transparent GAG film. The GAG film has sheet resistances of as low as ∼4.6 Ω/□ at the transmittance of ∼81% at 550 nm, and exhibited impressive mechanical robustness against bending, scratching and adhering. This excellent performance can be attributed to the superior properties of the high-quality graphene and its roles of not only connecting the discrete AgNWs but also binding them tightly by its restacking characteristic in a sandwich-structured form. The results suggest that the GAG film has potential applications in flexible electronic and optoelectronic devices.

•A two-step method was developed to enrich beta-carotene from 10 g/100 g beta-carotene concentrate.•Supercritical CO2 extraction was an effective way to remove impurities like oil and wax fraction.•Solvent extraction further boosted the pretreated beta-carotene concentrate from 16.5 g/100 g to 58.7 g/100 g.•Extraction and purification mechanisms by supercritical CO2 and solvent extraction were explained.Enriching natural 10 g/100 g β-carotene concentrate further is both meaningful and challenging issue. In this paper, a two-step technique has been reported to boost the concentration of natural β-carotene. Supercritical carbon dioxide (SC-CO2) was utilized to preconcentrate 10 g/100 g β-carotene made from crude palm oil followed with a solvent extraction. In the first step, the β-carotene concentration was preconcentrated to 16.7 g/100 g from 10 g/100 g when pretreating conditions were as follows: extraction temperature 60 °C, extraction pressure 20 MPa, extraction time 3 h, and CO2 flow rate 22 kg/h, In the second step, the β-carotene was boosted to 58.7 g/100 g from 16.7 g/100 g when the ratio of the preconcentrated sample and n-hexane solvent was 4:200 (g:mL), and the processing temperature was −5 °C. This is attributed to that SC-CO2 was able selectively to remove the impurities such as oil fraction. Removing impurities enable further purification of the beta-carotene with hexane extraction. The pretreatment of removing oil fraction using supercritical (SC-CO2) plays a vital role in the enrichment of β-carotene from 10 g/100 g β-carotene concentrates to higher content.

•Solubility of Quinine in Supercritical CO2 is reported for the first time•Solubility data have been correlated using five different approaches•Physical properties of Quinine are estimated by group contribution methods.•Interaction parameters are estimated for Quinine-SCCO2 system using PENG-ROBINSON et al. equations of stateSolubility of quinine in supercritical carbon dioxide (SCCO2) was experimentally measured in the pressure range of 8 to 24 MPa, at three constant temperatures: 308.15 K, 318.15 K and 328.15 K. Measurement was carried out in a semi-dynamic system. Experimental data were correlated by iso-fugacity model (based on cubic equations of state, CEOS), Modified Mendez–Santiago–Teja (MST) and Modified Bartle semi-empirical models. Two cubic equations of state: Peng–Robinson (PR) and Dashtizadeh–Pazuki–Ghotbi–Taghikhani (DPTG) were adopted for calculation of equilibrium parameters in CEOS modeling. Interaction coefficients (kij & lij) of van der Waals (vdW) mixing rules were considered as the correlation parameters in CEOS-based modeling and their contribution to the accuracy of model was investigated. Average Absolute Relative Deviation (AARD) between correlated and experimental data was calculated and compared as the index of validity and accuracy for different modeling systems. In this basis it was realized that the semi-empirical equations especially Modified MST can accurately support the theoretical studies on phase equilibrium behavior of quinine–SCCO2 media. Among the cubic equations of state DPGT within two-parametric vdW mixing rules provided the best data fitting and PR within one-parametric vdW mixing rules demonstrated the highest deviation respecting to the experimental data. Overall, in each individual modeling system the best fitting was observed on the data points attained at 318 K, which could be perhaps due to the moderate thermodynamic state of supercritical phase.

•Pristine graphene was prepared and could be uniformly distributed in PVA aqueous assisted with SDBS.•A vacuum dead-end micro-filtering method was developed to prepare graphene-PVA composite film.•The film had a layer-aligned structure in which conductivity network was formed well.•The film had excellent thermal conductivity, flexibility and heat dissipation performance.The graphene-based composite paper with high thermal conductivity has attracted increasing attention for many potential applications in thermal management systems. In this paper, we reported a pristine-graphene based poly vinyl alcohol (PVA) composite film with high thermal conductivity. Firstly, a concentration of the PVA aqueous solution was mixed with the pristine-graphene made by a green way of supercritical CO2 exfoliation to form the composite solution via non-covalent. Then, the composite solution was filtered through a porous cellulose filter membrane (CFM) by using a vacuum dead-end micro-filtration method. Finally, the film was obtained by peeling from CFM after drying. The characterization results indicate that the as-produced film had a layer-aligned structure and well flexibility. The graphene content of the films varied from 20 wt% to 65 wt%, and their thermal conductivity varied between 10.15 and 36.81 W/mk. The results of dissipating heat indicated the film with 20 μm thickness and 50 wt% graphene loading enabled the temperature of heat source to reduce by 8 °C, suggesting it can be potentially applied in thermal management system.

•Biocompatiable chitosan–graphene oxide hybrid was prepared using ultrasound.•The synthesis process is green and simple without organic solvent and catalyst.•Roles of ultrasound and supercritical CO2 in forming amidation were explained.Ultrasound-induced synthesis of chitosan-modified nano-scale graphene oxide (CS-NGO) hybrid nanosheets, which has great potential pharmaceutical applications, in supercritical CO2 without catalyst was presented for the first time. The preparation process does not require organic solvent and post-processing, and CO2 easily escapes from the product. The morphology and structure of the CS-NGO, characterized using scanning electron microscopy, transmission electron microscopy, infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis, confirms that it was combined via the amide linkage, and had excellent dispersibility and stability toward acidic and physiological aqueous solution, which implies that it could be used as a drug-carrier. The sonication power played a crucial role in inducing forming amidation, and the conversion rate increased with the sonication time. The mechanism of this reaction was explained.

•Curcumin proliposomes were prepared by SAS assisted with ultrasound.•Curcumin release could be controlled from the prepared proliposomes.•Curcumin proliposomes are highly stable under low temperature storage.Curcumin proliposome (CPL) was prepared using supercritical antisolvent technique assisted with ultrasound. The effects of the process parameters, such as weight ratio of starting material, pressure, temperature, and ultrasound power, on the entrapment efficiency (EE) and the drug loads were investigated. The latter three parameters were optimized using response surface methodology in terms of their effects on EE. The morphology and structure of the generated CPL were characterized by SEM, XRD and DSC. The in vitro release of the curcumin proliposome (CL) formed via hydration of the CPL was studied. The results indicated that the release of the curcumin could be controlled by manipulating the morphology of the CPL including the precipitation form of the starting materials, the particle size, and the particle fusion. The CPL was stable for at least 3 months at low temperature storage.

•Ultrasound gave significant help in controlling curcumin morphology and size.•The mixing state was analyzed by optical photographs of the jet flow.•Supersaturation and mixing speed determined shape and uniformity, respectively.Controllable morphology and size of crystal materials prepared by using a supercritical antisolvent (SAS) technique is still challenge. In this study, ultrasound was introduced into the SAS process to produce the particles of curcumin, a model compound. The effects of ultrasound power on the particle morphology and size were investigated in the range of 0 and 240 W at three different pressures. The observation of jet flow indicated ultrasound could accelerate the mixing speed between the liquid solution and the CO2, and thus reduced the gaseous region and the local saturation gradient. Mixed polymorphic and uniform particles of the curcumin were produced at a low and high mixing speed, respectively, confirmed by scanning electron microscopy. The needle- or rod-like particle, irregular lumpy particle and nano spherical particle were generated with the increase of the ultrasound power, attributed to the changes of the degree of supersaturation. Therefore, the ultrasound can be potentially applied to adjust the morphology and size of the crystal materials in supercritical CO2 antisolvent.

•Supercritical solvothermal synthesis of TiO2–pristine-graphene hybrid was presented.•TiO2 particles with around 5–10 nm were dispersed uniformly on the graphene sheets.•The hybrid enabled methyl orange dye to degrade almost completely in 180 min.•Excellent photocatalytivity of the hybrid is attributed to the effect of the graphene.A continuous supercritical solvothermal technique was developed for synthesizing TiO2–graphene hybrids, with the pristine graphene sheets used as the crystallization sites and the TiO2 nanoparticles crystallized on the graphene, forming the hybrids simultaneously. The structure and morphology of the fabricated hybrids were characterized via X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy. The uniform hybrids were obtained at different concentrations of graphene while the temperature, pressure and resident time were fixed at 350 °C, 23 MPa, and 30 s, respectively. The TiO2 particles formed on the hybrids were approximately 5–10 nm in size and dispersed uniformly. Compared with the pure TiO2 and the commercial P25, the photocatalytic efficiency of the hybrids was greatly enhanced. The hybrid enabled methyl orange dye to degrade almost completely in 180 min, while only 78% and 82% of the methyl orange dye was degraded separately by the pure TiO2 and P25. This enhanced photocatalytic performance of the hybrids is attributed to the well distributed-TiO2 and the rapid transfer of the photo-generated electrons from the surface of the catalyst to the graphene, thereby preventing a photo-generated electron–hole recombination.

The solubility of glycyrrhizin in supercritical carbon dioxide (SCCO2) with cosolvent ethanol at the mole fraction of (0, 0.02, and 0.04) was measured, respectively, at pressures of (9 to 21) MPa and temperatures of (308, 318, and 328) K. The results revealed that the glycyrrhizin solubility depended on the pressure, temperature, and cosolvent mole fraction. The glycyrrhizin solubility in pure SCCO2 was well correlated with Chrastil, Bartle, and Mendez-Santiago and Teja models with the average absolute relative deviation (AARD) below 6.82 %. The glycyrrhizin solubility in SCCO2 with cosolvent was correlated by Chrastil modified by González (Chrastil-G), and MST modified by Sauseau (MST-S) models with satisfactory AARD below 3.85 %. The results provide fundamental data in designing extraction of glycyrrhizin from the licorice or preparation of its particle using SCCO2 techniques.

•Insulin/PLGA–HPMC nanoparticle was prepared using modified supercritical antisolvent method.•High product yield and high insulin loading were obtained.•Influences of operating factors on the insulin/PLGA–HPMC characteristic were elucidated.•The insulin showed a controlled-release in gastric and intestinal simulating fluids.•Release profiles of the insulin were well correlated with the Katzendler kinetic mode.Nanoparticles of insulin/hydroxy-propyl-methylcellulose (HPMC)–poly-lactic-co-glycolic acid (PLGA) were successfully prepared by a modified supercritical CO2 anti-solvent technique. The particle size, yield and insulin content were significantly influenced by the mass ratio of PLGA to HPMC and the mass ratio of insulin to the blend of PLGA–HMPC as well as by the operating pressure, temperature and ultrasonic vibration power. Uniform particles were obtained with the smallest size of 35 nm, the maximum product yield of 88%, and the highest insulin loading of 55.2%. X-ray powder diffraction patterns and Fourier transform infrared spectra revealed that the insulin and the polymers were uniformly combined in the matrix, and no new chemical group was formed. An in vitro assessment of the insulin/HPMC–PLGA depicted a controlled release of insulin in both the gastric and the intestinal simulating fluids. Release profiles were accurately fitted to the Katzendler–Hoffman kinetic model with regression parameters of 0.9856 and 0.9771 for the intestinal and gastric simulating liquids, respectively.

A modified supercritical antisolvent method, aiming at high yielding and high loading, is developed for preparation of drug-loaded polymeric nanoparticles. The modified method consists of three alternate stages: injecting solution via a nozzle into a precipitation vessel filled with supercritical CO2, static agitation, and washing of precipitated particles with supercritical CO2. The process stages are continuously repeated until ending injection of a desired amount of solution. The ultrasound operates during the entire process. Poly(lactic-co-glycolic acid) (PLGA) and curcumin are model components. The influences of the process parameters on the yielding and loading are investigated. The maximum yield of the curcumin–PLGA nanoparticles 50 nm in size and the curcumin loading in it reach 96% and 45%, respectively. High yield, high loading, and uniform size are attributed to the efficient mixing between solution droplets and antisolvent, and sequential washing using an antisolvent under ultrasonic agitation. Experimental data are fitted and optimized by neural network simulation.

This study demonstrates a new route for converting bio-oil, prepared from the hydrothermal liquefaction of cornstalks, to diesel- and jet-fuel-range hydrocarbons over Ni/ZrO2 in supercritical cyclohexane. Under relatively mild conditions (573 K, 5 MPa H2), we obtained a high yield (81.6 C%) of hydrocarbons with an excellent quality (90% of diesel- and jet-fuel-range hydrocarbons and 7% of gasoline-range hydrocarbons). Ni/ZrO2 efficiently and stably catalyzed all types of compounds in the bio-oil to the corresponding alkanes via hydrogenation, dehydration, hydrogenolysis, decarbonylation, and isomerization, without polymerizations among the different reactive compounds in bio-oil. The activity and selectivity for diesel- and jet-fuel-range hydrocarbons of Ni/ZrO2 showed no obvious changes after three cycles. Ni/ZrO2 was fairly stable in supercritical cyclohexane after 72 h of reaction time. This strategy provides a novel high-efficiency pathway for the preparation of high-quality hydrocarbons from bio-oil.

A simple, cost-effective approach is presented for producing exfoliated films of pure graphene or polymer–graphene composite with high yield, high conductivity, and processability. The approach combines supercritical CO2 with ultrasonics. Characterization by Raman spectroscopy combined with atom force field microscopy demonstrates that the graphene sheets were obtained with 24% as monolayers, 44% as bilayers, and 26% as trilayers. The layer number and lateral size of graphene sheets can be controlled by adjusting the process parameters. The yield of graphene sheets with a lateral size of about 0.5–5.0 μm is about 16.7 wt % under optimum conditions, which can be easily raised to 40–50 wt % by repeated exfoliation of the sediment that remained in the reactor. The resultant pure graphene film made by filtration has a high electrical conductivity of 2.8 × 107 S/m. The electrical conductivity of the film of polyvinyl alcohol–graphene composite is 300 S/m.

•Method of supercritical antisolvent combined with fluidization was developed.•PLGA-coated nanocurcumin particles were produced with enhanced loading efficiency.•Profile of sustained release of curcumin in vitro accorded with the Higuchi model.Nano-curcumin was coated by poly(lactic-co-glycolic acid) (PLGA) using a novel fluidization assisted supercritical anti-solvent procedure. PLGA solution was sprayed into supercritical CO2 media, in which nano-curcumin particles were fluidized by ultrasonic vibration. The influences of process parameters, such as solvent types, solution concentrations, CO2 flow rates, the ratio of PLGA to curcumin, and ultrasonic power on the particles size and the curcumin loading were investigated. Scanning electron microscopy, laser particle size analyzer, and differential scanning calorimetry were used to characterize as-produced samples in terms of the structure, morphology and particle size distribution. The PLGA-curcumin nano-capsules were obtained with the average size of 63 nm and the loading of 38%, under the ultrasonic power of 210 W, and with the average size of 40 nm and 36% loading, at the ultrasonic power of 350 W. In vitro studies prove that proposed method is successful in preparing sustained release systems.

•Preparation of graphene by ultrasonic in supercritical CO2 is developed.•Single- and few-layer graphene sheets are exfoliated from graphite directly.•Ultrasonic power affects the number of graphene layers and their lateral sizes.•As-exfoliated graphenes heighten electrochemical performance of LiFePO4 cathode.•The specific capacity of the LiFePO4/graphene composite cathode achieves 160 mAh/g.This study reports a novel strategy using ultrasound in supercritical CO2 for exfoliating graphite directly into single and few-layer graphene sheets. The mutually complementary characterizations of the as-exfoliated samples via atomic force microscopy, transmission electron microscopy and Raman spectroscopy indicate that the ultrasonic power greatly affects the number of layers and the lateral size of the graphene. Single-layer graphene with a lateral size of 50–100 nm and two-layer graphene with a lateral size of 0.5–10 μm are obtained using an ultrasonic power of 300 and 120 W, respectively. As-exfoliated graphene sheets heighten the electrochemical performance of LiFePO4 cathode materials, demonstrating graphene's remarkable electrical conductivity. The specific capacity of the LiFePO4/graphene composite cathode achieves 160 mAh/g and displays stable cycling for more than 15 cycles. This technique will enable cost-effective mass production of graphene sheets with good quality, and the as-exfoliated graphene will find wide applications, including lithium-ion batteries.

•A continuous solvothermal route for producing ZnO-graphene composites is developed.•Two different structures of ZnO-graphene, a film-grain and a cobweb, are obtained.•The synthesis mechanism of ZnO-graphene in solvothermal media is illustrated.•ZnO-graphene exhibits excellent photocatalytic activity in degrading methyl orange.A continuous solvothermal approach is presented for fabricating ZnO-graphene hybrid nanoparticles with enhanced photocatalytic activity. The approach combines continuously delivering the graphene ethanol solution and the ZnO precursor ethanol solution simultaneously into the reactor. It takes only seconds to forming ZnO-graphene composites. The structure and morphology of the fabricated samples are characterized via X-ray diffraction, scanning electron microscopy, transmission electron microscope and scanning transmission electron microscope. Two types of the hybrid composites, a film-grain and a cobweb composite, are obtained at the different concentrations of the precursor while the temperature, the pressure and the resident time are 160 °C, 7 MPa, and 30 s, respectively. The synthesis mechanism is illustrated. The resultant hybrids exhibit excellent photocatalytical activity in degrading methyl orange dye in water. The degradation rate reaches almost 100% in 200 min. The degradation increases 30% compared with the bare ZnO. This enhanced photocatalytical performance of the ZnO-graphene hybrids attributes to the rapidly transfer of the photo-generated electrons from the surface of the catalyst to the graphene, preventing the photo-generated electron–hole pairs from the recombination. We believe that this continuous solvothermal approach can be a general way to prepare metal oxide-graphene composites with unique properties.

A facile and general approach was developed to exfoliate layer materials to produce two-dimensional atomic crystals. A single and few layers of BN, MoS2, and WS2 were obtained via directly exfoliating their powder materials using supercritical CO2 assisted with ultrasound. The effects of supercritical CO2 coupled with ultrasound play a key role in the exfoliation process. The layer numbers and sizes of the BN, MoS2, and WS2 can be easily controlled by adjusting the power and the time of ultrasonication. The AFM images suggest single-layered BN, MoS2, and WS2 were produced, respectively. Their lateral sizes are about 0.5–2 μm, and almost 90% of the BN sheets are less than five layers. The electric diffraction patterns demonstrate that the crystallinities of the produced samples remained the same as that of the raw material during the exfoliating process. This novel technique is cost-effective and scalable, and can be widely used in the production of two-dimensional atomic crystals with high quality.

Ultrasonic pretreatment was developed to increase conversion of cellulose to bio-oil in hot-compressed water. The physical structures of cellulose were greatly changed by ultrasonic pretreatment, resulting in excellent swelling and dispersion of cellulose in the water. With the increased surface area and decreased crystallinity and degree of polymerization of cellulose, the bio-oil yield was increased remarkably. The highest bio-oil yield (61.5%) was obtained at 260 °C with a residence time of 0 min for the 1 h pretreated cellulose. Under the optimum reaction conditions, ultrasonic pretreatment increased the bio-oil yield by 22.1% and reduced residence time by 5 min. GC-MS analysis results showed that ultrasonic pretreatment affected the chemical compositions of bio-oils and significantly improved the content of 5-hydroxymethylfurfural in heavy oils.

An ultrasonic pretreatment method was developed to enhance the yield of bio-oil obtained from the liquefaction of cornstalks in hot-compressed water at different reaction temperatures (260–340 °C) and residence times (0–40 min). Influences of ultrasonic pretreatment on the physicochemical properties of cornstalks and bio-oil yields were investigated. The results show that ultrasonic pretreatment obviously increases surface areas of cornstalks, decreases crystallinities, and erodes the structures of lignin, leading to more exposure of cellulose and hemicellulose. The yield of bio-oil was increased remarkably by 10.1% for 40 min sonicated cornstalks under the optimum liquefied conditions (300 °C for 0 min of residence time). Carbon balance indicates that ultrasonic pretreatment increases the carbon conversion of cornstalks to heavy oil and water-soluble oil. Energy balance indicates that the sonicated cornstalks have positive energy efficiencies. GC-MS analyses demonstrate ultrasonic pretreatment increases the contents of the phenols in heavy oil and water-soluble oil.

•ZnO nanoparticles with controllable size and morphology were synthesized in the continuous hot compressed water method.•The size and morphology of ZnO nanoparticles are temperature dependent.•Tubular ZnO nanostructures were synthesized when oleic acid was added to the reaction.•A scaled-up process (output of ZnO: 1 kg/h) produced ZnO nanocrystals of a similar size to those produced on the small scale.ZnO nanocrystals were synthesized using the continuous hot compressed water technique at different temperatures and reaction times. The size, crystallinity and morphology of the ZnO nanocrystals were characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction techniques. Star-like, spherical nanoparticles with diameters varying from 10 to 200 nm and rod-like structures with lengths up to 300 nm were obtained. Tubular ZnO nanocrystals were obtained when oleic acid was added in situ into the feeding solutions during the reaction. The corresponding growth mechanisms were elucidated. A scaled-up process (output of ZnO: 1 kg/h) produced ZnO nanocrystals of a similar size to those produced on the small scale.Graphical abstract

A modified supercritical antisolvent technique (solution enhanced dispersion with enhanced mass transfer using ultrasound in supercritical CO2, SEDS-EM) has been applied in preparation of PEG loaded PLA nanoparticles. The hydrophilicity of polylactic acid (PLA) nanoparticles has been increased by adding polyethylene glycol (PEG) in order to improve PLA as a controlled release drug system. Uniform distribution of solution tiny droplets by the SEDS-EM method in supercritical CO2 prevents particle agglomeration as well as intensifies the effect of mass transfer. The effects of PEG amount in the PLA/PEG polymer mixture and ultrasonic system on the formation of PLA-PEG nanoparticles have been studied. Operational parameters, such as temperature, pressure, ultrasound power supply and solution flow rate have been also investigated in the current paper. The morphology of PLA-PEG nanoparticles changed from hollow combined structure to nearly spherical form by decreasing the amount of PEG in the PLA/PEG polymer mixture. In addition, particle size reduction has been achieved by decreasing temperature, solution flow rate as well as by increasing pressure and providing ultrasound treatment.The solution can be generated into extremely small droplets during SEDS-EM, which induces the enhanced mass transfer in the supercritical CO2 and the prevention of agglomeration of particles.Highlights► A novel method, solution enhanced dispersion in supercritical CO2 with enhanced mass transfer (SEDS-EM), is established to prepare PLA-PEG nanoparticles. ► In this new technique, the solution can be generated into very small droplets, which induces the enhanced mass transfer between supercritical CO2 and solvent. ► Compared with SEDS techniques, SEDS-EM can provide smaller and more uniform particles.

Thalidomide treats multiple myeloma and protracts life-span of patient, but its bioavailability is limited as it is poorly water soluble. Thalidomide nano-flakes are produced to improve the drug dissolution rate. Two nanoflake production methods are utilized for a comparative study: a supercritical antisolvent (SAS) method and a supercritical antisolvent with enhanced mass transfer (SAS-EM). SAS-EM utilizes ultrasonication to improve dispersion upon injection within the supercritical carbon dioxide. Comparative study of SAS and SAS-EM thalidomide confirmed that the application of ultrasonication improved the micro/nano particles produced by SAS. The effects of ultrasound power on the formation of thalidomide particles are examined. The particle size and morphology were characterized by SEM. The thalidomide nano-flakes produced by SAS-EM were smaller than the particles produced by SAS. Dissolution rates of the produced particles, evaluated by HPLC, demonstrated an increase in the thalidomide dissolution rate for the SAS-EM produced particles. The polymorphs and crystallinity of thalidomide particles (flakes) were observed by FTIR and XRD. In this research, the supercritical processing significantly modified the crystal formation of thalidomide from an original state of a β-polymorph to the amorphous state α-polymorph after supercritical processing.Comparative study confirmed that supercritical antisolvent with enhanced mass transfer (SAS-EM) can produce smaller and more uniform thalidomide nano-flakes with increased dissolution rate in water than with SAS.

In recent years, the solution enhanced dispersion in supercritical fluids (SEDS) technique is widely applied to produce fine and small particles of drugs and other active ingredients. However, this technique still cannot be used to generate particles in the submicrometer range for specific compounds, such as carotenoids. In this study, a modified SEDS technique is explored and applied in the preparation of β-carotene nanoparticles with relatively narrow size distribution. This novel technique, termed SEDS-EM, combines a traditional SEDS technique with ultrasonication from the supercritical antisolvent with enhanced mass transfer precipitation technique (SAS-EM). For this new technique, the β-carotene solution is premixed with the antisolvent (supercritical CO2) in a coaxial nozzle; then the mixed solution is sprayed from the coaxial nozzle onto a surface vibrating at an ultrasonic frequency. The solution jet is dispersed by the coaxial nozzle and further atomized into very small droplets by the ultrasonic vibrating surface. This combination of a coaxial nozzle and the ultrasound field enhances the mass transfer between the solution and the antisolvent. The resultant β-carotene particles decreased in size from the micrometer range (2–5 μm) by SEDS to the nanometer range (20–205 nm) by SEDS-EM. This smaller particle size can be controlled by the power supplied from the attached ultrasound transducer utilized in SEDS-EM. The size and morphology of the particles are observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of the process parameters on the β-carotene yield are discussed. The crystallography transformation of the processed and unprocessed β-carotene is characterized by XRD and FTIR. The particle precipitation in sub and near critical regions of the DCM-CO2 binary system is also discussed.

Experimental data for the phase behavior of system n-hexane (C6H14) + ethanol (EtOH) + carbon dioxide (CO2) at temperatures from (308.5 to 328.5) K are presented. Bubble point and cloud point pressures were measured using a variable-volume view cell as functions of temperature, ratio between C6H14, EtOH, and CO2. The effect of temperature and CO2 concentration on bubble point pressure was investigated. In addition, the Peng–Robinson equation of state (PR-EOS) with one binary interaction parameter was used in correlating the experimental data of bubble point at 313.5 K. The results show that the PR-EOS can correlate the experimental data of the bubble point pressure.

The scavenging ability of alpha-lipoic acid (ALA) towards superoxide anions, hydroxyl radicals and hydrogen peroxide was evaluated by means of chemiluminescence (CL). In neutral or acid conditions, ALA could scavenge superoxide anions and its scavenging efficiency depended on its concentration. In neutral or alkaline conditions, the CL intensity of the reaction of ALA with hydroxyl radical (OH radicals) decreased after the first 10 min and then increased with time, suggesting that ALA could scavenge OH radicals at the beginning, but yielded unknown intermediate products that could lead to the increase of CL intensity at later stages. The increase of CL intensity in the reaction of hydrogen peroxide with ALA may also be due to these products.

A rapid and continuous method for production of LiFePO4/C nanoparticles in super heated water is described, wherein soluble starch was used as carbon precursor. The effects of pH, flow rate, temperature, and pressure on the formation of LiFePO4/C particles were investigated. Results showed that the pH value was the key factor on the formation of phase pure LiFePO4, which only formed at pH = 7; the LiFePO4/C occurred as particles with about 70-200 nm size and LiFePO4 was covered by a thin carbon layer; higher flow rate, higher pressure, and lower temperature led to smaller particles of LiFePO4/C.

Vitamin D3 (VD3) proliposomes (VDP), consisted of hydrogenated phosphatidycholine (HPC) and VD3, were prepared using supercritical anti-solvent technology (SAS). The effects of operation conditions (temperature, pressure and components) on the VD3 loading in VDP were studied. At the optimum conditions of pressure of 8.0 MPa, temperature of 45°C, and the mass ratio of 15.0% between VD3 and HPC, the VD3 loading reached 12.89%. VD3 liposomes (VDL) were obtained by hydrating VDP and the entrapment efficiency of VD3 in VDL reached 98.5%. The morphology and structure of VDP and VDL were characterized by SEM (scanning electron microscope), TEM (transmission electron microscope) and XRD (X-ray diffractometer). The structure of VD3 nanoparticles in HPC matrix was formed. The size of VDL with an average diameter of about 1μm was determined by dynamic light scattering instrument (DLS). The results indicated that VDP can be made by SAS and VDL with high entrapment efficiency can be formed easily via the hydration of VDP.

The submicroparticles of β-sitosterol were produced by using an aerosol solvent extraction system (ASES) and characterized by scanning electronic microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) analysis. The effects of operational parameters including pressure, temperature, solution concentration, and ratio of flow rate (CO2/solution, r) on particle size (PS), yield, and morphology were investigated. The results showed that microparticles of β-sitosterol (less than 1000 nm size and larger than 70% yield) could be obtained at 10-15 MPa, 35–50°C, 15 mg·ml−1, 10/1(r); β-sitosterol particles were found to occur as three mophologies: flakes, rods, and spheres by varying ratio of flow rate or solution concentration. In contrast, the crystallinity of β-sitosterol decreased, whereas its molecular structure remained almost unchanged after being ASES-treated. Therefore, ASES was an effective method to produce submicroparticles of β-sitosterol.