In this work, the encapsulation of rice bran oil extracted using supercritical CO2 has been studied. In the first stage, the emulsification process by high pressure homogenization was studied and ...optimized. The effect of the working pressure (60–150 MPa), the composition of the carrier (mixtures of pea protein isolate (PPI) and maltodextrin (MD), from 50 to 90% of PPI) and the carrier to oil ratio (2–4) on the emulsion droplet size (EDS) was studied. To minimize the EDS, moderate pressures (114 MPa), a carrier composed mainly by PPI (64%) and carrier to oil ratios around 3.2 were required. The emulsion obtained in the optimal conditions (EDS = 189 ± 3nm) was dried using different technologies (spray-drying, PGSS-drying and freeze drying). The supercritical CO2 based drying process (PGSS) provided spherical particles that resulted in the smallest average size (but broader distribution) and lower encapsulation efficiency (53 ± 2%).
Food science; Food technology; Pea protein; Encapsulation; microfluidization; Rice bran oil; Spray drying; PGSS
This paper presents micromachined on-chip RF passive bandpass filters at 1-8 GHz based on utilizing a three-pole LC low-pass filter and two dc-blocking capacitors, which is accomplished with a GaAs ...monolithic-microwave-integrated-circuit process. The microwave design model of the bandpass filters that take into account conductor losses is given and verified. Using this model, the RF bandpass filter with a tunable center frequency and a desirable bandwidth can be realized. Due to only a planar spiral inductor required in the design, the layout size of the filter is less than 700μm × 400μm. Furthermore, in order to minimize the effect of substrate losses caused by the inductor on the bandpass filter, metal shores (MSs) and patterned ground shields (PGSs) are located and inserted between the inductor and the GaAs substrate, respectively, and a cavity on the backside of the inductor substrate is processed by the via-hole etching technique. Measurement results demonstrate that RF bandpass filters without MS and PGS show agreement with the design performance and those with MS and PGS have resulted in the improvement of about 24% insertion loss and a slight effect on the center frequency.
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•PEG 6000/CO2 system was used as a model to investigate thermodynamic and transport data.•Density, viscosity and interfacial tension of CO2 saturated PEG 6000 solution were ...measured.•Interfacial tension and viscosity were correlated with particle size and particle morphology.
In our study, a PEG 6000/CO2 system was used as a model in order to investigate basic thermodynamic and transport data such as density, viscosity and interfacial tension of a CO2 saturated PEG 6000 solution. Additionally, particle size and particle morphology were correlated for the first time with the interfacial tension and viscosity of a PEG 6000 CO2 saturated solution. Binary systems were measured at four temperatures: 333 K, 343 K, 353 K and 363 K from ambient pressure up to pressure of 35 MPa. Density increases linearly with increasing pressure and is significantly reduced with increasing temperature at isobaric conditions. Interfacial tension is reduced when the pressure increases; on the other hand, temperature effect is minimal. Temperature variation has a significant effect on viscosity reduction. The addition of CO2 and consequently increasing pressure result in even lower viscosity.
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A series of biodegradable P(L)LA-PEG1.5kDa-P(L)LA copolymers have been synthesized and compared as processing aid versus Poloxamer 407 (PEO–PPO–PEO), in the formulation of protein ...encapsulated microparticles, using supercritical carbon dioxide (scCO2). Bovine serum albumin (BSA) loaded microcarriers were prepared applying the particles from the gas saturated solutions (PGSS) technique using scCO2 and thus, avoiding the standard practice of organic solvent encapsulation. Four triblock copolymers were synthesized and characterized, particularly in terms of thermal properties and behaviour when exposed to scCO2. The effects of the inclusion of these copolymers in the formulation of poly(α-hydroxy acids) based microparticles – e.g. poly(d,l-lactic-co-glycolic acid) (PLGA) and poly(d,l-lactide) (PLA) – were analysed in terms of yield, particle size, morphology and drug release. The use of P(L)LA-PEG1.5kDa-P(L)LA triblock copolymers were found to increase the yield of the PGSS-based process and to decrease the size of the microparticles produced, in comparison with the formulation containing the Poloxamer 407. Moreover the microparticles formulated with the triblock copolymers possessing the higher hydrophobic character were able to maintain a controlled drug release profile.
The aim of this study was to develop, for the first time, anthocyanin-enriched fractions from black raspberry pomace (BRP) using ultrasound-assisted extraction (UAE) via sonotrode and the Particles ...from Gas-Saturated Solutions (PGSS) process. UAEs with different amplitudes and sonication times were evaluated and showed relevant effects on the yields of target analytes. The raspberry pomace extracts were formulated in a powder form by PGSS using glyceryl monostearate as a carrier at different extract-to-carrier ratios of 1:11, 1:5, and 1:3. The effects of all variables were evaluated in terms of extraction yield, total phenolic content, and encapsulation yield. UAE was strongly affected by amplitude, and the highest amplitude (100%) provided the best results for extraction yield and total phenolics. HPLC of UAE extracts and powders was utilized for quantification of polyphenol compounds, showing cyanidin-3-rutinoside as a main compound, followed by cyanidin-3-glucoside, rutin, ellagic acid, and gallic acid. These results show that these time-efficient and high-performance techniques enable the production of natural fractions from industrial BRP with acceptable characteristics to be used for the development of nutraceuticals and different food formulations.
Peer grading is a natural crowdsourcing application, where dispersed students/peers resources are collected to evaluate others' assignments. Peer grading also offers a promising solution for scaling ...evaluation and learning to large-scale educational systems. A key challenge in peer grading is motivating peers to grade diligently and provide a high-quality evaluation. Spot-checking (SC) mechanisms, allowing instructors to check evaluations, can prevent peer collusion where peers grade arbitrarily and coordinate to report the uninformative grade. However, existing SC mechanisms unrealistically assume that peers have the same grading reliability and cost. This is limiting in practice, where we would expect peers to differ in reliability and cost. This article proposes the general Optimal SC (OptSC) model of determining the probability that each assignment needs to be checked to maximize assignments' evaluation accuracy aggregated from peers and takes into consideration: 1) peers' heterogeneous characteristics and 2) peers' strategic grading behaviors to maximize their own utility. We prove that the bilevel OptSC is NP-hard to solve. By exploiting peers' grading behaviors, we first formulate a single-level relaxation to approximate OptSC. By further exploiting structural properties of the relaxed problem, we propose an efficient algorithm to that relaxation, which also gives a good approximation of the original OptSC. Extensive experiments on both synthetic and real data sets show significant advantages of the proposed algorithm over existing approaches.
•Limonene encapsulation in modified starch via Particle from Gas Saturated Solutions or Suspensions (PGSS).•Study of suspensions with limonene, modified starch and ethanol.•Characterization of ...microparticles via laser scanning confocal microscopy and scanning electron microscopy.•Limonene extraction from particles and quantification using gas chromatography.•PGSS as technological innovation for starch modified encapsulation is feasible and efficient when compared with conventional method.
Supercritical CO2 was studied for impregnation or encapsulation of essential oils in modified starches via Particle from Gas Saturated Solutions or Suspensions (PGSS). Modified starches were choose as function of its low cost. The advantage of this method over conventional encapsulation that use modified starch via spray drier refers to the low temperatures used and absence of water in the process. Modified starch presents hydrophobic elements and this molecules present amphiphilic character. Usually it is employed in the encapsulation of essences as wall material with excellent volatiles retention due to its polar and nonpolar interface. Considering its hydrophobic characteristics, interactions between the modified starch and supercritical CO2 occurred, resulting in two different structural interactions of the limonene and modified starch in the PGSS (50°C and 60°C at 100bar and 120bar). When hydrous ethanol was used in the suspension, impregnation occurred and, when anhydrous ethanol was used, encapsulation occurred. Analysis of particle morphology via scanning electron and confocal microscopy, thermo-oxidative characterization by differential scanning calorimetry and determination of microencapsulated limonene via gas chromatography coupled to mass spectrometry indicated limonene microencapsulation and impregnation occurred despite the highly solubility of limonene in supercritical CO2. The retention of limonene by Purity Gum Ultra® was 86% when encapsulated and, 53% when impregnated, similar values to those obtained in conventional microencapsulation methods via a spray drier or via PGSS-drying.
This paper presents a design approach for improving energy-efficiency and throughput of parallel architectures in near- and subthreshold voltage circuits. The focus is to suppress leakage energy ...dissipation of the idle portions of circuits during active modes, which can allow us to wholly transform the throughput improvement from parallel architectures into energy savings via deep voltage scaling. We begin by investigating the efficacy of parallel and pipeline architectures in the near- and subthreshold circuits. The investigation reveals that active energy dissipation largely undermines the ability of deep voltage scaling to transform excessive throughput into energy savings. Techniques, such as power-gating switches (PGSs), can mitigate active-leakage power dissipation; however, the overhead for entering and exiting sleep modes can offset the energy savings provided by sleep mode, particularly if sleep time is fine grained for suppressing active leakage. Therefore, in this paper, we propose a PGS design technique, inspired by the so-called zigzag supercutoff CMOS, in order to optimize the overheads of mode transitions of PGS in near- and subthreshold circuits. The proposed technique enables to have circuits in sleep mode for as short as a single clock cycle with a negligible amount of energy and delay overheads. We apply our proposed design to parallel multiplier-based test circuits operating at near- and subthreshold voltages. Simulations show a significant improvement in energy-efficiency over baselines at the same throughput.
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•Micronization of the pharmaceutical excipient tristearin by the PGSS process.•Gaining of metastable α-forms of tristearin immediately after the processing.•The lower the ...pre-expansion pressure the higher the degree of crystallinity.•Stabilization of the metastable crystal form α in case of low pressure drops.•Increase of transformation tendency of the metastable α-form by emulsifier.
The bioavailability of a pharmaceutical depends on the crystal structure of a polymorphic active ingredient or excipient. By changing the process parameters of the PGSS (Particles from Gas Saturated Solutions) process i.e. thermodynamic conditions of the solidification process it is possible to vary the crystal modification of polymorphic products. In a series of PGSS experiments microparticles of the polymorphic excipient tristearin as well as of mixtures of tristearin and the emulsifier sorbitan monolaurate were successfully produced. Pre-expansion pressure was varied between 6 and 22MPa. The effects of process dependent parameters on the crystallization were investigated via scanning electron microscopy, differential scanning calorimetry and X-ray powder diffraction.
Metastable α-forms of tristearin were found immediately after the processing for all experiments. Further it was found that it is possible to shift the conversion rate of polymorphic transitions in the product either by varying the process parameters or by adding the emulsifier.
Traditional methods for solids processing involve either high temperatures, necessary for melting or viscosity reduction, or hazardous organic solvents. Owing to the negative impact of the solvents ...on the environment, especially on living organisms, intensive research has focused on new, sustainable methods for the processing of these substances. Applying supercritical fluids for particle formation may produce powders and composites with special characteristics. Several processes for formation and design of solid particles using dense gases have been studied intensively. The unique thermodynamic and fluid-dynamic properties of supercritical fluids can be used also for impregnation of solid particles or for the formation of solid powderous emulsions and particle coating, e.g., for formation of solids with unique properties for use in different applications. We give an overview of the application of sub- and supercritical fluids as green processing media for particle formation processes and present recent advances and trends in development.
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