P2O5-Promoted Efficient and Diastereoselective Synthesis of Substituted 5-Methylene-dihydropyran-2,6-diones and 3-Methylene-3,4-dihydropyran-2-ones

A simple, efficient, and diastereoselective synthesis of 5-methylene-dihydropyran-2,6-diones and 3-methylene-3,4-dihydropyran-2-ones from substrates afforded by the S_N2 reaction between the acetyl derivatives of the Baylis–Hillman adducts and methylacetoacetate or acetylacetone or benzoyl acetone via saponification followed by P₂O₅-mediated cyclization is described.     

Synthesis of spirooxindolocarbamates based on Betti reaction: antibacterial,antifungal and antioxidant activities

Molecular Diversity - A series of new spirooxindolocarbamates 4a–l and 6a–d were synthesized by using the Betti reaction. All the target compounds were well characterized by IR, NMR and...     

Transferability of optical bowing parameters between binary and ternary group-IV alloys

We present a detailed analysis of the compositional dependence of the average of the E₁ and E₁+Δ₁ transition energies in Ge_1−x−ySi_xSn_y alloys. We show that this dependence can be explained in terms of three bowing parameters—b^SiGe, b^GeSn, and b^SiSn—which scale with the product ΔχΔR of the Phillips electronegativity and size mismatches between Si, Ge, and Sn.     

High-field magnetoresistance and magnetothermal e.m.f. in many-valley semiconductors with ellipsoidal energy surface

Thermomagnetic coefficients appropriate to a many-valley model of a semiconductor of the n -Germanium type are evaluated in the framework of the density matrix formalism developed earlier. These coefficients are determined for arbitrary values of the magnetic field, within the effective mass approximation. The phonon-drag contribution is not included in this work. An application is made to the four-ellipsoidal model of n-Ge under the conditions where elastic-acoustic phonon scattering is the predominant mechanism of scattering and the high-temperature limit of the phonon distribution is valid. The thermoelectric power (magneto-Seebeck effect) is found to increase with increasing values of the magnetic field except for a small region of low magnetic field values where it decreases in the longitudinal configuration only.     

Synthesis of polymer-supported Brønsted acid-functionalized Zn–porphyrin complex,knotted with benzimidazolium moiety for photodegradation of azo dyes under visible-light irradiation

Research on Chemical Intermediates - A polymer-supported Brønsted acid-functionalized Zn–porphyrin complex, knotted with benzimidazolium moiety (PSBAZnPP), has been synthesized and...     

Benchtop NMR analysis of piperazine-based drugs hyperpolarised by SABRE

Piperazine-based drugs, such as N-benzylpiperazine (BZP), became attractive in the 2000s due to possessing effects similar to amphetamines. Herein, BZP, in addition to its pyridyl analogues, 2-, 3-, and 4-pyridylmethylpiperidine (2-PMP, 3-PMP, and 4-PMP respectively) was subjected to the hyperpolarisation technique Signal Amplification By Reversible Exchange (SABRE) in order to demonstrate the use of this technique to detect these piperazine-based drugs. Although BZP was not hyperpolarised via SABRE, 2-PMP, 3-PMP, and 4-PMP were, with the ortho- and meta-pyridyl protons of 4-PMP showing the largest enhancement of 313-fold and 267-fold, respectively, in a 1.4-T detection field, following polarisation transfer at Earth's magnetic field. In addition to the freebase, 4-PMP.3HCl was also appraised by SABRE and was found not to polarise, however, the addition of increasing equivalents of triethylamine (TEA) produced the freebase, with a maximum enhancement observed upon the addition of 3 equivalents of TEA. Further addition of TEA led to a reduction in the observed enhancement. SABRE was also employed to polarise 4-PMP.3HCl (~20% w/w) in a simulated tablet to demonstrate the forensic application of the technique (138-fold enhancement for the ortho-pyridyl protons). The amount of 4-PMP.3HCl present in the simulated tablet was quantified via NMR using D₂O as a solvent and compared well to complimentary gas chromatography–mass spectrometry data. Exchanging D₂O for CD₃OD as the solvent utilised for analysis resulted in a significantly lower amount of 4-PMP.3HCl being determined, thus highlighting safeguarding issues linked to drug abuse in relation to determining the amount of active pharmaceutical ingredient present.     

Rotating Detonation Combustor Research at the University of Cincinnati

Rotating detonation combustors (RDC) are at the forefront of pressure gain combustion (PGC) research. The simplicity in design and the ease of assembly makes it a promising technology that could be integrated into existing combustor architectures. This is, however, coupled with the considerable complexities of the detonation-based flow field, and the associated modes and coupling mechanisms. The current paper is an overview of the research done at the University of Cincinnati to address some of the challenges and questions pertaining to the physics of RDC operation. Issues such as combustor geometry, injection schemes and mixing, varied reactants behavior and modes of RDC operation are discussed. The effects of pressurization of the combustor, along with other detonation enhancement strategies are also deliberated upon. When appropriate, parallels are drawn to the phenomena of high frequency combustion instabilities to address the similarities in observations between the two fields.     

Approximation by the Complex form of a Link Operator Between the Phillips and the Szász–Mirakjan Operators

Results in Mathematics - The link operator $${P_{\alpha}^\rho(f,x)=\sum_{k=1}^\infty s_{\alpha,k}(x)\int_0^\infty \theta_{\alpha,k}^\rho(t)f(t)dt+e^{-\alpha x}f(0)}$$ , $${\alpha, \rho >...