368 research outputs found

    Solubility Measurement Method and Mathematical Modeling in Supercritical Fluids

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    Supercritical fluids technology (SFT) is gaining significance application in the field of food and drug processing. Since supercritical fluid possess dual characteristic of gas and liquid, it exhibits outstanding extraction features such as high penetration ability and able to dissolve materials. To aid the design of processes including extraction, separation, purification, and synthesis, solubility data of compound of interest is required. In addition, with the solubility data, a more environmental friendly and productive operating condition can be resulted. However, there is lack of review that summarizes the method and correlation to gain this data. Thus, the review is accomplished to give concise discussion on the fundamental knowledge of solubility. This review will discuss the solubility measurement method, quantification method and mathematical correlation models for explaining the thermodynamic relationship of solubility

    Solubility of Camphene and Caryophyllene Oxide in Subcritical and Supercritical Carbon Dioxide

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    The solubility of camphene and caryophyllene oxide in subcritical and supercritical carbon dioxide were determined using dynamic off-line analysis method. Under subcritical condition, solubility of camphene and caryophyllene oxide were (1.738 to 18.118) ∙ 10^-3 and (1.84 to 7.872) ∙ 10^-3 respectively at 298.15 K with pressure varied from 50 to 70 bar. At 302.15 K and under same pressure variation, solubility of camphene and caryophyllene oxide were (1.918 to 18.76) ∙ 10^-3 and (14 to 25.624) ∙ 10^-3 respectively. Under supercritical condition, experiments were run from 80 bar to 250 bar. Solubility of camphene was ranged from (54.024 to 151.67) ∙ 10^-3 at 308.15 K and (17.552 to 65.487) ∙ 10^-3 at 313.15 K; while solubility of caryophyllene oxide was ranged from (24.9 to 299.94) ∙ 10^-3 at 308.15 K and (2.542 to 102.359) ∙ 10^-3 at 318.15 K. These solubility data was correlated with three semi-empirical models which were Bartle, Chrastil and Mendez-Santiago-Teja model. Of these three models, Mendez-Santiago-Teja model showed excellent fitting with average absolute relative deviation kept below 2%

    Influence of silica gel in production of diacylglycerol via enzymatic glycerolysis of palm olein

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    Enzymatic glycerolysis was explored in this paper for the production of diacylglycerol (DAG) oils from palm olein. Three commercial enzymes, Lipozyme TL IM, Lipozyme RM IM and Novozym 435 were used for their ability to synthesize DAG in a solvent‐free system. Novozym 435 was found to be the more effective enzyme, resulting in a high DAG production even in the absence of an adsorbent such as silica gel. The yields of DAG were between 43 and 50 wt‐%. Lipozyme TL IM and RM IM, being supported on hydrophilic materials, require an adsorbent to allow slow release of glycerol for reaction with the enzyme and oil. In the absence of silica, no reaction was observed. The success of the reaction is therefore very dependent on the amount of silica used. The yields of DAG using Lipozyme TL IM and RM IM were 52 and 45 wt‐%, respectively. In addition, the degree of reduction in tocopherols and tocotrienols appeared correlated with the efficacy of the glycerolysis reaction. Changes in the slip melting points and solid fat contents of the products are indicative of the reaction occurring

    Fire behaviour of gypsum plasterboard wall assemblies: CFD simulation of a full-scale residential building

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    New trends in building energy efficiency include thermal storage in building elements that can be achieved via the incorporation of Phase Change Materials (PCM). Gypsum plasterboards enhanced with micro-encapsulated paraffin-based PCM have recently become commercially available. This work aims to shed light on the fire safety aspects of using such innovative building materials, by means of an extensive experimental and numerical simulation study. The main thermo-physical properties and the fire behaviour of PCM-enhanced plasterboards are investigated, using a variety of methods (i.e. thermo-gravimetric analysis, differential scanning calorimetry, cone calorimeter, scanning electron microscopy). It is demonstrated that in the high temperature environment developing during a fire, the PCM paraffins evaporate and escape through the failed encapsulation shells and the gypsum plasterboard's porous structure, emerging in the fire region, where they ignite increasing the effective fire load. The experimental data are used to develop a numerical model that accurately describes the fire behaviour of PCM-enhanced gypsum plasterboards. The model is implemented in a Computational Fluid Dynamics (CFD) code and is validated against cone calorimeter test results. CFD simulations are used to demonstrate that the use of paraffin-based PCM-enhanced construction materials may, in case the micro-encapsulation shells fail, adversely affect the fire safety characteristics of a building. © 2015 Elsevier Ltd. All rights reserved

    The Small Muscle-Specific Protein Csl Modifies Cell Shape and Promotes Myocyte Fusion in an Insulin-like Growth Factor 1–Dependent Manner

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    We have isolated a murine cDNA encoding a 9-kD protein, Chisel (Csl), in a screen for transcriptional targets of the cardiac homeodomain factor Nkx2-5. Csl transcripts were detected in atria and ventricles of the heart and in all skeletal muscles and smooth muscles of the stomach and pulmonary veins. Csl protein was distributed throughout the cytoplasm in fetal muscles, although costameric and M-line localization to the muscle cytoskeleton became obvious after further maturation. Targeted disruption of Csl showed no overt muscle phenotype. However, ectopic expression in C2C12 myoblasts induced formation of lamellipodia in which Csl protein became tethered to membrane ruffles. Migration of these cells was retarded in a monolayer wound repair assay. Csl-expressing myoblasts differentiated and fused normally, although in the presence of insulin-like growth factor (IGF)-1 they showed dramatically enhanced fusion, leading to formation of large dysmorphogenic “myosacs.” The activities of transcription factors nuclear factor of activated T cells (NFAT) and myocyte enhancer–binding factor (MEF)2, were also enhanced in an IGF-1 signaling–dependent manner. The dynamic cytoskeletal localization of Csl and its dominant effects on cell shape and behavior and transcription factor activity suggest that Csl plays a role in the regulatory network through which muscle cells coordinate their structural and functional states during growth, adaptation, and repair

    Structure-guided design of purine-based probes for selective Nek2 inhibition

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    Nek2 (NIMA-related kinase 2) is a cell cycle-dependent serine/threonine protein kinase that regulates centrosome separation at the onset of mitosis. Overexpression of Nek2 is common in human cancers and suppression can restrict tumor cell growth and promote apoptosis. Nek2 inhibition with small molecules, therefore, offers the prospect of a new therapy for cancer. To achieve this goal, a better understanding of the requirements for selective-inhibition of Nek2 is required. 6-Alkoxypurines were identified as ATP-competitive inhibitors of Nek2 and CDK2. Comparison with CDK2-inhibitor structures indicated that judicious modification of the 6-alkoxy and 2-arylamino substituents could achieve discrimination between Nek2 and CDK2. In this study, a library of 6-cyclohexylmethoxy-2-arylaminopurines bearing carboxamide, sulfonamide and urea substituents on the 2-arylamino ring was synthesized. Few of these compounds were selective for Nek2 over CDK2, with the best result being obtained for 3-((6-(cyclohexylmethoxy)-9H-purin-2-yl)amino)-N,N-dimethylbenzamide (CDK2 IC50 = 7.0 μM; Nek2 IC50 = 0.62 μM) with >10-fold selectivity. Deletion of the 6-substituent abrogated activity against both Nek2 and CDK2. Nine compounds containing an (E)-dialkylaminovinyl substituent at C-6, all showed selectivity for Nek2, e.g. (E)-6-(2-(azepan-1-yl)vinyl)-N-phenyl-9H-purin-2-amine (CDK2 IC50 = 2.70 μM; Nek2 IC50 = 0.27 μM). Structural biology of selected compounds enabled a partial rationalization of the observed structure activity relationships and mechanism of Nek2 activation. This showed that carboxamide 11 is the first reported inhibitor of Nek2 in the DFG-in conformation

    Extreme sensitivity of the spin-splitting and 0.7 anomaly to confining potential in one-dimensional nanoelectronic devices

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    Quantum point contacts (QPCs) have shown promise as nanoscale spin-selective components for spintronic applications and are of fundamental interest in the study of electron many-body effects such as the 0.7 x 2e^2/h anomaly. We report on the dependence of the 1D Lande g-factor g* and 0.7 anomaly on electron density and confinement in QPCs with two different top-gate architectures. We obtain g* values up to 2.8 for the lowest 1D subband, significantly exceeding previous in-plane g-factor values in AlGaAs/GaAs QPCs, and approaching that in InGaAs/InP QPCs. We show that g* is highly sensitive to confinement potential, particularly for the lowest 1D subband. This suggests careful management of the QPC's confinement potential may enable the high g* desirable for spintronic applications without resorting to narrow-gap materials such as InAs or InSb. The 0.7 anomaly and zero-bias peak are also highly sensitive to confining potential, explaining the conflicting density dependencies of the 0.7 anomaly in the literature.Comment: 23 pages, 7 figure

    Passive Transdermal Systems Whitepaper Incorporating Current Chemistry, Manufacturing and Controls (CMC) Development Principles

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    In this whitepaper, the Manufacturing Technical Committee (MTC) of the Product Quality Research Institute has updated the 1997 Transdermal Drug Delivery Systems Scale-Up and Post Approval Change workshop report findings to add important new product development and control principles. Important topics reviewed include ICH harmonization, quality by design, process analytical technologies, product and process validation, improvements to control of critical excipients, and discussion of Food and Drug Administration’s Guidance on Residual Drug in Transdermal and Related Drug Delivery Systems as well as current thinking and trends on in vitro–in vivo correlation considerations for transdermal systems
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