Constituents of cannabis sativa L. XII—mass spectral fragmentation patterns for some. Cannabinoid acid as their TMS derivatives

Fragmentation schemes for a number of TMS derivatized cannabinoid acids are described. Specific fragmentation pathways and rearrangement mechanisms were determined based on the ion composition of deuterium labeled derivatives. Significant differences in the mode of fragmentation of the two isomeric Δ⁹-tetrahydrocannabinolic acids are described. These results are based on information obtained from deuterium labeling and high resolution data or by the extension of previously reported mechanisms for neutral cannabinoids. Comparisons of the fragmentation schemes between the neutral and acidic cannabinoids are used to confirm many of the fragmentation mechanisms.     

Efficient access to some new pyrimidine derivatives and their antimicrobial evaluation

1-[4-(3-Hydroxyphenyl)-6-methyl-2-thioxo-1,2,3,4-tetrahydropyrimidin-5-yl]ethanone ( 1 ) was used as a precursor for heterocyclic synthesis. Condensation of compound 1 with monochloroacetic acid and benzaldehyde gave thiazolopyrimidine 2 which in turn underwent cyclization with malononitrile dimmer to afford malononitrile derivative 3 . Also, the reaction of compound 1 with benzaldehyde under a basic condition produced chalcone 4 . Chalcone 4 can be used as a key intermediate for further preparation of heterocyclic compounds. In addition, compound 1 was allowed to react with malononitrile dimmer and/or ethyl chloroacetate to give pyrimidines 8 and 9 , respectively. Alkylation of compound 8 with ethyl chloroacetate afforded S-alkylated product 10 which was treated with hydrazine hydrate to yield the hydrazino derivative 11 . Alternative synthesis of compound 10 was taken place through reaction of compound 9 with malononitrile dimmer. The biological activity of the synthesized compounds was investigated. Compounds 1 , 4 , 5 , and 8 recorded high activities against Gram positive bacteria (S. aureus). Structures of the new synthesized compounds were elucidated by elemental analysis and spectral data.     

Effect of confined LO-phonons interactions on polarons in quantum well wires

Summary  The energy of an electron interacting with the confined longitudinaloptical (LO) phonons in a rectangular quantum well wire is calculated as a function of the length of one size of the wires by a modified Lee-Low-Pines variational method. It is shown that in a very small wire the electron self-energy has a peak. But for larger wires, the self-energies increase monotonically. It is also found that the energies of the quasi-one-dimensional polaron are related to the sizes of the crosssection rather than to the cross-sectional area of the wire. The authors of this paper have agreed to not receive the proofs for correction.     

Direct Observation of Dissipation in Dynamical Search Algorithm using Transmon Qubits

Following recent work [Fortschritte der Physik 66, 1700080 (2018)], the dissipation effect of the dynamical quantum search algorithm (DQSA) is investigated. Such an algorithm is realized with the interaction of multi superconducting transmon qubits inside a 3D bus cavity. The dissipation of such system is caused by managing the sensitivity to charge noise via tuning the qubit frequency by employing Josephson energy. The probabilities of marked and unmarked states for the present algorithm have been calculated analytically and numerically. Such probabilities of marked states are sensitive to any change in the dissipation parameter. A deficiency causes the dissipation for the marked states, and that deficiency is added to the unmarked states. It is interesting to mention that one of the datasets at large dissipation rates gives an observation of the marked states probabilities which is related to the decoherence free subspace. It is predicted that the algorithm can be successfully implemented in the current experiments.     

Sulfur stable isotope distribution of polysulfide anions in an (NH4)2Sn aqueous solution

Methylation of polysulfides [(NH4)2Sn)] by reaction with CF3SO3CH3 followed by separation of the produced dimethylpolysulfides by liquid chromatography and subsequent highly accurate stable isotope analysis by a continuous-flow isotope ratio mass spectrometer shows that polysulfide anions in an aqueous solution exchange isotopes with the other sulfur species in the system. It demonstrates for the first time that polysulfide anions are 34S-enriched in equilibrium relative to total sulfur as a function of their sulfur chain length.     

Computational Studies of Atmospheric-Pressure Methane–Hydrogen DC Micro Glow Discharges

Atmospheric-pressure methane–hydrogen micro glow discharges were computationally investigated using a 2-D hybrid model. The plasma model was solved simultaneously with a model for the external circuit. Simulations were conducted for a pin-to-plate electrode configuration with an interelectrode separation of 400 ${rm mu}hbox{m}$. The spatiotemporal evolutions of electrons, species densities, electric field, and electron and gas temperatures were studied. A total of 81 reactions were considered, which included electron–neutral, electron–ion, ion–neutral, and neutral–neutral reactions. An 84-step reaction mechanism consisting of 15 surface species and four deposited bulk species was considered. A time-stepping technique was employed to address the time scales of plasma transport (in microseconds) and neutral and fluid transport (in milliseconds) in 2-D simulations with detailed volume and surface chemistry. The simulations indicated $hbox{H}_{3}^{+}$ and $hbox{CH}_{5}^{+}$ ions to be the most prominent hydrogen and hydrocarbon ions. The gas temperature predictions suggested the discharge to be operating as a nonthermal glow discharge. The effect of discharge current on both plasma and deposition characteristics was studied. The simulations predicted a flat voltage–current characteristic, indicating the discharge to be operating in normal glow mode. The predicted voltage–current characteristic was found to be in favorable agreement with the experimental measurements. With an increase in discharge current, the deposition rate profile expanded in the lateral direction, suggesting that deposition occurred at the cathode spot.      

Dissipative solitons compounds in a fiber laser. Analogy with the states of the matter

We investigate experimentally ordered and disordered pattern formation of solitons in a double-clad fiber laser. We point out an analogy between the different states of matter and the states of a set of dissipative solitons. In particular, we have identified a gas, a supersonic gas flow, a liquid, a polycrystal and a crystal of solitons. The different states are obtained only by adjustment of the intracavity phase plates.