Two new quinones from Iris bungei

Two new benzoquinone derivatives, bungeiquinone (1) and dihydrobungeiquinone (2), and two known derivatives, 3-hydroxyirisquinone (3) and 3-hydroxydihydroirisquinone (4), were isolated from the roots of Iris bungei. The structures of the new compounds were established on the basis of spectroscopic methods.     

Modified solutions of some oscillators by iteration procedure

The modified solutions of some nonlinear oscillators have been obtained based on the classical iteration procedure. In this article we have used the Fourier series and utilized all of its terms (sometimes approximately) in each iterative step. The third and fourth approximate frequencies of different nonlinear problems show good agreement with the exact values.     

Anomalously Large Antiphase Signals from Hyperpolarized Orthohydrogen Using a MOF-Based SABRE Catalyst

Hyperpolarized orthohydrogen (o-H₂) is a frequent product of parahydrogen-based hyperpolarization approaches like signal amplification by reversible exchange (SABRE), where the hyperpolarized o-H₂ signal is usually absorptive. We describe a novel manifestation of this effect wherein large antiphase o-H₂ signals are observed, with ¹H enhancements up to ≈500-fold (effective polarization P_H≈1.6 %). This anomalous effect is attained only when using an intact heterogeneous catalyst constructed using a metal–organic framework (MOF) and is qualitatively independent of substrate nature. This seemingly paradoxical observation is analogous to the “partial negative line” (PNL) effect recently explained in the context of Parahydrogen Induced Polarization (PHIP) by Ivanov and co-workers. The two-spin order of the o-H₂ resonance is manifested by a two-fold higher Rabi frequency, and the lifetime of the antiphase HP o-H₂ resonance is extended by several-fold.     

Accessing Dihydropyrrolo[3,4-b]indol-1(2H)-ones via Pd-Catalyzed Intramolecular Aminocarbonylative Ring Closure

Present in a number of small molecule derivatives that display a wide range of biological activities, the dihydropyrrolo[3,4-b]indol-(2H)-one (DHPI) core represents an underexplored heterocyclic scaffold. Given the pharmaceutical potential of the DHPI motif, the development of synthetic methodologies that permit their expedient assembly would be highly desirable. Herein, we describe a novel strategy for the construction of the DHPI core from 3-iodo-1H-indolyl substrates, employing an unprecedented Pd-catalyzed intramolecular aminocarbonylative ring closure. The compatibility of our optimized protocol with various functional groups is highlighted through the synthesis of a range of diversely substituted DHPI derivatives in up to 90 % isolated yield.     

Geometric deduction of the solutions to modular equations

The Ramanujan Journal - In his notebooks, Ramanujan presented without proof many remarkable formulae for the solutions to generalized modular equations. Much later, proofs of the formulae were...     

Forecasting the impact of environmental stresses on the frequent waves of COVID19

Nonlinear Dynamics - A novel approach to link the environmental stresses with the COVID-19 cases is adopted during this research. The time-dependent data are extracted from the online repositories...     

Novel Indole-Pyrazine Alkaloid: Synthesis,Characterization, and Crystal Structure

Crystallography Reports - A heterocyclic molecule of a novel class with a multiple ring system has been synthesized using a new and simple strategy and acetic acid as catalyst. The structure of the...     

New structures for closed-form wave solutions for the dynamical equations model related to the ion sound and Langmuir waves

This treatise analyzes the coupled nonlinear system of the model for the ion sound and Langmuir waves.The modified(G'/G)-expansion procedure is utilized to raise new closed-form wave solutions.Those solutions are investigated through hyperbolic,trigonometric and rational function.The graphical design makes the dynamics of the equations noticeable.It provides the mathematical foundation in diverse sectors of underwater acoustics,electromagnetic wave propagation,design of specific optoelectronic devices and physics quantum mechanics.Herein,we concluded that the studied approach is advanced,meaningful and significant in implementing many solutions of several nonlinear partial differential equations occurring in applied sciences.