A Comprehensive Review on the Techniques for Extraction of Bioactive Compounds from Medicinal Cannabis

Cannabis is well-known for its numerous therapeutic activities, as demonstrated in pre-clinical and clinical studies primarily due to its bioactive compounds. The Cannabis industry is rapidly growing; therefore, product development and extraction methods have become crucial aspects of Cannabis research. The evaluation of the current extraction methods implemented in the Cannabis industry and scientific literature to produce consistent, reliable, and potent medicinal Cannabis extracts is prudent. Furthermore, these processes must be subjected to higher levels of scientific stringency, as Cannabis has been increasingly used for various ailments, and the Cannabis industry is receiving acceptance in different countries. We comprehensively analysed the current literature and drew a critical summary of the extraction methods implemented thus far to recover bioactive compounds from medicinal Cannabis. Moreover, this review outlines the major bioactive compounds in Cannabis, discusses critical factors affecting extraction yields, and proposes future considerations for the effective extraction of bioactive compounds from Cannabis. Overall, research on medicinal marijuana is limited, with most reports on the industrial hemp variety of Cannabis or pure isolates. We also propose the development of sustainable Cannabis extraction methods through the implementation of mathematical prediction models in future studies.     

The effects of vinylic and allylic fluorine substitution in iso-butylene

Molecular orbital calculations using the 3-21G basis set have been performed for iso-butylene (IB; 2-methyl-1-propene), difluoro-iso-butylene (DFIB; 1,1-difluoro-2-methyl-1-propene), hexafluoro-iso-butylene (HFIB; 3,3,3-trifluoro-2-(trifluoromethyl)-1-propene), and perfluoro-iso-butylene (PFIB; 1,1,3,3,3-pentafluoro-2-(trifluoromethyl)-1-propene). The effects of fluorine substitution were studied by comparison of several calculated quantities of the fluorinated compounds with those of IB. Through an analysis of the computed electron density distributions, it is suggested that a vinylic fluorine acts as a π acceptor, by electron transfer into the C? F bond, and a π repeller, by polarization of the adjacent π electrons. An allylic fluorine acts as a π attractor through electrostatic effects, although in HFIB a minor contribution from hyperconjugation was evident. Finally, electrostatic potentials for the molecules were calculated. These show that fluorine substitution has large effects on the electrostatic potential associated with the π electrons. These effects change the sign of the calculated electrostatic potential in the plane containing the π bond to such an extent that PFIB is quite susceptible to nucleophilic attack.     

Degradation phenomena in gallium aluminium arsenide stripe geometry lasers

Gallium aluminium arsenide cw stripe lasers are capable of operating for at least several years at room temperature. However, both bulk and surface degredation still occur. Point defects incorporated during processing and strain associated with oxide isolation layers can influence bulk degradation; facet protection modifies surface effects. At higher temperatures, bond deterioration and localized bulk effects are more important than at room temperature. In order to justify the validity of temperature overstress testing, degradation mechanisms must be shown to be the same under operational and overstress conditions. Statistical analysis of data suggests that higher temperature degradation data cannot automatically be extrapolated via an Arrhenius-type relationship to yield meaningful operational lives.The authors are grateful to A. R. Goodwin, P. A. Kirkby and B. Wakefield for access to information prior to publication and, together with P. W. Hutchinson and R. B. Plumb, for making available unpublished information. The devices discussed in this paper were fabricated at STL Ltd Harlow, supported, in part, by a BPO Contract. Acknowledgement is made to the Director of Research of the British Post Office for permission to publish this paper.     

Friction parameter of an ion near a metal surface

The force on an ion located near a condensed-matter surface determines its Brownian motion along the surface. We have studied the dissipative component of this force using a model in which the ion interacts with a metal while moving parallel with its surface. We recover the known asymptotic form of the force for large separations when only electron-hole excitations are accounted for but find a different form when damping of collective states is included.     

Dopant patterning in three dimensions during molecular beam epitaxial growth using anin-situfocused ion gun

Conventional molecular beam epitaxial (MBE) growth of III-V semiconductor material systems use a thermal silicon effusion cell as the n-type dopant source. In the technique described here, the thermal source is replaced with a scanning Si focused ion gun. It is therefore possible to directly write dopant patterns into the semiconductor waferit as it is being grown. The precise control over the elemental composition in the growth (z) direction permitted by MBE, combined with high spatial resolution of the focused dopant ion beam in the lateral (xy) plane, allows direct registration of fully integrated, three-dimensional semiconductor structures and devices otherwise unobtainable via conventional lithographic techniques. In this paper, we present electrical measurements of high mobility GaAs/AlGaAs modulation doped heterostructures fabricated using this technique.Fabrication of novel undoped channel FET structures is also discussed, where the dopant beam is used to form extended contacts to the induced electron gas. FET action is demonstrated for the first time using this technique, eliminating the constraint for self-alignment in undoped structures.     

Protonation of CIS-PBO in metanesulfonic acid solutions

A comparative study of the conductivity behavior of methane-sulfonic acid solutions of poly(p-phenylene-cis-benzobisoxazole) or cis-PBO and other compounds, including CH₃SO₃Na (NaMSA), a cis-PBO model compound, and 6,7-dimethyl-2,3-di(2-pyridyl) quinoxaline, a molecule containing four protonating sites, was carried out to determine the degree of protonation of PBO and its model compound. The conductivity dependence with increasing cis-PBO concentration indicates that only two sites per repeat unit are protonated. © 1994 John Wiley & Sons, Inc.     

Photoproduction of eta mesons from hydrogen

The differential cross section for eta photoproductions has been measured for incident photon energies of 4 and 8 GeV and momentum tranfers −t = 0.3 to 0.8 (GeV/c)².