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Cannabis research is challenging since the plant is illegal in most countries. There are also other difficulties in researching the effects of cannabis. Many people who smoke cannabis also smoke tobacco. Another difficulty researchers have is in recruiting people who smoke cannabis into studies. Because cannabis is an illegal drug in many countries, people may be reluctant to take part in research, and if they do agree to take part, they may not say how much cannabis they actually smoke.
A review found that the use of high CBD-to-THC strains of cannabis showed significantly fewer positive symptoms such as delusions and hallucinations, better cognitive function and both lower risk for developing psychosis, as well as a later age of onset of the illness, compared to cannabis with low CBD-to-THC ratios.
Cannabis use started to become popular in the United States in the s. Private use of cannabis was legalized in September after a unanimous decision by the Constitutional Court in Johannesburg. Media related to Cannabis at Wikimedia Commons. From Wikipedia, the free encyclopedia. Cannabis A flowering cannabis plant. Medical cannabis from state-controlled production: Anlage III , other cannabis: Schedule I legal in 9 states for recreational use UN: Entheogenic use of cannabis.
Long-term effects of cannabis. History of cannabis and Timeline of cannabis law. Prohibition of drugs and Drug liberalization. Illegal but often unenforced. Marijuana and the Cannabinoids.
Retrieved 13 December Retrieved 12 January Retrieved 28 September Retrieved 9 October Retrieved 17 July American Heritage Dictionary of the English Language. See also article on Marijuana as a word. Spanish Word Histories and Mysteries: Pharmacology, Toxicology, and Therapeutic Potential. National Institute on Drug Abuse. Retrieved 19 April Retrieved 12 July Manual of forensic emergency medicine: Jones and Bartlett Publishers.
World Drug Report Retrieved 26 June Retrieved 9 September Retrieved 30 October National Conference of State Legislatures. Retrieved 3 July Retrieved 19 October National Institute of Drug Abuse. The term medical marijuana refers to using the whole unprocessed marijuana plant or its basic extracts to treat a disease or symptom.
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Cannabinoid function in learning, memory and plasticity. Handbook of Experimental Pharmacology. Marijuana Cannabis sativa L. Medical Toxicology of Drug Abuse: Synthesized Chemicals and Psychoactive Plants. Retrieved 14 July The American Journal on Addictions. Retrieved 1 November Are All These Hoops Necessary? Brazilian Archives of Biology and Technology. Drugs and the Making of the Modern World. Greater Than the Sum of Their Parts? Retrieved 7 April There is clear evidence that recreational cannabis can produce a transient toxic psychosis in larger doses or in susceptible individuals, which is said to characteristically resolve within a week or so of absence Johns European Archives of Psychiatry and Clinical Neuroscience.
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Psychiatry and Clinical Neurosciences. The most consistently reported brain alteration was reduced hippocampal volume which was shown to persist even after several months of abstinence in one study and also to be related to the amount of cannabis use Other frequently reported morphological brain alterations related to chronic cannabis use were reported in the amygdala the cerebellum and the frontal cortex These findings may be interpreted as reflecting neuroadaptation, perhaps indicating the recruitment of additional regions as a compensatory mechanism to maintain normal cognitive performance in response to chronic cannabis exposure, particularly within the prefrontal cortex area.
Evidence from Studies of Adult Users". Neuroscience and Biobehavioral Reviews. This may reflect the multitude of cognitive tasks employed by the various studies included in these meta-analyses, all of which involved performing a task thereby requiring the participant to reorient their attention and attempt to solve the problem at hand and suggest that greater engagement of this region indicates less efficient cognitive performance in cannabis users in general, irrespective of their age.
Cannabis, cognition and addiction" PDF. Journal of Neuroimmune Pharmacology. A systematic review of human and animal evidence". Experimental and Clinical Psychopharmacology. Therefore, results indicate evidence for small neurocognitive effects that persist after the period of acute intoxication As hypothesized, the meta-analysis conducted on studies eval- uating users after at least 25 days of abstention found no residual effects on cognitive performance These results fail to support the idea that heavy cannabis use may result in long-term, persistent effects on neuropsychological functioning.
Journal of Clinical Pharmacology. Cannabis appears to continue to exert impairing effects in executive functions even after 3 weeks of abstinence and beyond. While basic attentional and working memory abilities are largely restored, the most enduring and detectable deficits are seen in decision-making, concept formation and planning.
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Office for Official Publications of the European Communities. A year prospective study of young Australians". Retrieved 5 November The Journal of School Health. In these recent years, the development of flavor and fragrance industries are remarkably fast due to the rapid development of food, cosmetics, and perfume industries.
Thousands of new artificial flavor and fragrance compounds have also been produced to fulfill high demand for food, cosmetics, and perfume industries.
Different flavor substances can be found in natural products, and most of them have high economic value. One of them is acetophenone. Collin, "Aroma extraction dilution analysis of Sauternes wines. Key role of polyfunctional thiols", J.
There are numbers of natural products contain acetophenone such as apple, apricot, banana, and cauliflower [ 2 P. Gutierrez, "Phenolic-compound-extraction system for fruit and vegetable samples", J. The extraction process using organic solvent may be the most commonly used methods to obtain the acetophenone from natural products.
However, this method possesses several disadvantages such as low purity and requires several stages of purification of the resulting product [ 4 C. Patent 2,, , Extraction using supercritical CO 2 is one of viable alternatives that can be used in aroma and fragrance industries. The working procedures are relatively straightforward and produce high extraction yields with high purity, and shorter extraction time [ 4 C.
Another advantage of using supercritical fluid is the elimination of subsequent separation processes such as distillation and crystallization.
For the design of the supercritical extraction process of acetophenone from the natural matrices, the equilibrium or solubility data of acetophenone-supercritical CO 2 is needed. Currently, several literatures [ 5 A. Maurer, "High-pressure vapor liquid equilibria in binary mixtures of carbon dioxide and aromatic hydrocarbons: Sharafeev, "Waste management in propylene epoxidation process with the use of supercritical fluid media", Am.
Bamberger and Maurer [ 5 A. The determination of the solubility of aromatic hydrocarbons in supercritical carbon dioxide was conducted gravimetrically. The measurements were performed at temperatures between K and K at pressures up to 18 MPa. Recently, Gumerov et al. They used dynamic flow method to extract and to obtain the solubility those hydrocarbons, and one of the hydrocarbons was acetophenone.
Since all of the previous studies emphasized on the dynamic system, in the current study we focused on the combination of static system and gravimetrically method.
Therefore, one of the objectives of this study is to obtain the solubility data of acetophenone on supercritical carbon dioxide at various pressures and temperatures.
To obtain the solubility data of compounds in the supercritical fluid SCF in a wide range of pressures and temperatures, is tedious, expensive, and time consuming work. In most cases, the data obtained from the experiments usually only valid in a narrow range of pressures and temperatures. To overcome this problem, usually a mathematical model which valid for a wide range of pressures and concentrations is needed. This mathematical model is usually developed from the limiting number of experimental data.
In this paper, we employed density based models Chrastil and Del Valle — Aguilera and equation of state EoS approach Peng-Robinson to correlate the experimental solubility data of acetophenone in supercritical carbon dioxide.
The solubilities of acetophenone in supercritical carbon dioxide were measured at four different temperatures Acetophenone C 8 H 8 O is a yellow liquid with a boiling point of Acetophenone used in this study was obtained as analytical standard and supplied by Sigma-Aldrich CAS no: Food grade carbon dioxide with the purity of Analytical grade ethanol was used to dissolve the acetophenone in the sample collector.
In order to control and maintain the temperature, oven memmert Germany was used. Another part of the system was equilibration column Swagelok, USA. The entire components, fittings, and tubing used in the system were made of stainless steel Swagelok, USA.
The maximum working pressure and temperature of the supercritical system was 30 MPa and The solubility of acetophenone in supercritical CO 2 was obtained in the static mode. Brief descriptions of the experimental procedure are described as follow [ 7 S. Ismadji, "Solubility of methyl salicylate in supercritical carbon dioxide at several temperatures", J. The oven was turned on, and the system was heated until the desired temperature was reached After the thermal equilibrium condition had been reached, the liquid CO 2 was pumped to the equilibration column using a high pressure pump.
Since the static method was used in this study, during the processes, valves V-2 was closed, while valves V-1 was kept open. After the equilibrium condition had been achieved, then the sampling tube was disconnected from the system by closing valve V The sample in the sampling tube was released by opening valve V-2 to the collector containing a known amount of ethanol to fully separate acetophenone and carbon dioxide.
At least three replicated samples were taken at the experimental condition, and equilibrium composition was determined by averaging the replications. The concentration of acetophenone in ethanol was determined by means of a Shimadzu gas chromatograph GC provided with a flame ionization detector. Gas chromatography was calibrated externally using acetophenone solutions with different concentrations.
Schematic diagram of supercritical apparatus. Liquid CO2 cylinder; 2. High pressure pump; 3. Digital pressure indicator; 5. The operational conditions for GC are described as follows: DB Wax; 2 oven: The solubilities of acetophenone in supercritical CO 2 were measured at temperatures ranging from The experimental solubility data of acetophenone in supercritical carbon dioxide are given in Table 1 and also plotted in Fig. The densities of carbon dioxide at several pressures and temperatures were predicted using Stryjek and Vera modification of the Peng-Robinson equation of state [ 8 R.
An improved peng-robinson equation of state for pure compounds and mixtures", Can. Experimental solubility of acetophenone in supercritical CO 2 as a function of pressure at different temperatures: Where P and V are pressure and molar volume, respectively, R is the gas constant; T c and P c are the critical temperature and critical pressure of the pure component, respectively.
From the experimental data shown in Fig. This phenomenon can be explained by the effect of the solvent density on the solubility of the solute at supercritical condition: The solubility data of acetophenone in supercritical CO 2 expressed in mole fraction are ranging from 0. Below crossover region, the solubility of acetophenone in supercritical carbon dioxide decreases with increasing temperature, but above the crossover region, the opposite phenomenon is observed.
The crossover region was observed at a pressure range between 11 and 16 MPa. This phenomenon can be explained by two crucial factors density of the SCF and the solute vapor pressure which affected by the change of temperature. As the temperature increases, the density of SCF decreases but the solute vapor pressure increases. These two factors have the tendency of opposite effects on the solubility curve. The effect of density seems to be dominant in the low pressure region and cause the decrease of the solute solubility as the temperature increases, while, the solute vapor pressure seems to be dominant in the high pressure region hence the solute solubility increased as the temperature increases [ 9 M.
Krukonis, Supercritical Fluid Extraction: Principles and Practices , Butterworths: Huang, "Kawl, and Y. The density-based equations, are the most widely used models to correlate the solubility of various compounds in supercritical fluids, due to its simplicity and do not require any critical physical properties.
The earliest known of the density based model was developed by Chrastil [ 12 J. Chrastil, "Solubility of solids and liquids in supercritical gases", J. He developed the model based on the theory of the solvato complex formation in equilibrium, one molecule of solute A associates with k molecules of solvent B to form a solvato complex AB k.
His semiempirical model has the mathematical form as follows:. Parameter a is a constant, which depends on the heat of vaporization and solvation enthalpies of the solute. Parameter b is a function of the association number and the molecular weights of the solute and supercritical fluids. This parameter is not affected by changing of temperature [ 12 J.
In order to obtain the parameters k, a , and b , the fitting of the solubility experimental data was conducted for all temperatures simultaneously using a nonlinear least square method by minimizing the following sum of squared errors as the objective function. Where C exp is the experimental solubility of acetophenone in supercritical CO 2 , C cal is the calculated solubility, and N is the number of experimental data.
Table 2 represents the fitting parameters values and the sum of squared errors of Chrastil equation. Table 2 and Fig. The sum of the squared error value of the data fitting is 0.
Chrastil plot of acetophenone solubility in scCO 2 as a function of temperature and density. From the value of parameter a in the Table 2 , the total enthalpies of vaporization and solvation of the solute can be estimated to be The negative value of the parameter a means that the associating process is an endothermic process.
Limonene was the principal component extracted, the optimum conditions for limonene Furthermore, the effect of CO2 flow rate and particle size of orange peel was studied in the range Do you want to read the rest of this article? of particle size and the effect of mass flow of CO 2 on the extraction rate of essential oil. This Dissertation is brought to you for free and open access by DigitalCommons @URI. properties of supercritical C02 are summarized in Table 2. 4. to an uniform condition within the nucleating medium, and hence in principle to narrow . Table The density of carbon dioxide from the Bender equation and .. Supercritical CO2 is the most commonly used solvent in extraction processes, .. make use of the RESS process to reduce the particle size and narrow the.