Tris(2‐aminoethyl)amine‐based ferrocene‐terminated dendrimers as burning rate catalysts for ammonium perchlorate‐based propellant decomposition

Ferrocene‐based derivatives show potential application as burning rate catalysts (BRCs) for solid composite propellants. However, migration problems of simple ferrocene‐based derivatives limit their application as BRCs in solid composite propellants. To overcome the migration problems of ferrocene‐based BRCs and to enhance the burning rate of ammonium perchlorate (AP)‐based propellants, zero‐ to second‐generation tris(2‐aminoethyl)amine‐based ferrocene‐terminated dendrimers (G0, G1 and G2) were synthesized. The structures of G0, G1 and G2 were confirmed using ¹H NMR, Fourier transform infrared and UV–visible spectroscopies. The electrochemical behavior of G0, G1 and G2 was investigated using cyclic voltammetry. It was found that G0, G1 and G2 showed redox behavior due to the presence of ferrocene and this redox behavior was diffusion controlled over the investigated scan range. The burning rate catalytic effect of G0, G1 and G2 on thermal decomposition of AP was investigated using thermogravimetry and differential thermogravimetry. G0, G1 and G2 showed good catalytic effect on the thermal decomposition of AP. Anti‐migration studies showed that migration of G0, G1 and G2 was much slower than that of 2,2‐bis(ethylferrocenyl)propane (catocene) and ferrocene.     

Isothiocyanates as derivatization reagents in the determination of 1, 1-dimethylhydrazine by gas chromatography coupled with mass spectrometry

Alkyl isothiocyanates were proposed for the determination of 1, 1-dimethylhydrazine (DMH) in the form of 4-alkyl-l, l-dimethylthiosemicarbazides by gas chromatography coupled with mass spectrometry (GC-MS). 4-Alkyl-l, l-dimethylthiosemicarbazides are selectively formed under mild conditions in the absence of catalysts. During the chromatography, these thiosemicarbazides are efficiently resolved from excess of alkyl isothiocyanates. A possibility of identification of DMH derivatives on the basis of the chromatographic retention parameters and fragmentation data under electron ionization conditions was demonstrated.     

Application of two-spinor calculus in quantum mechanical and field calculations

This paper describes Lorentz two-spinors and proposes using them in calculations with Dirac four-spinors and quaternions.     

Penalty Method for Variational Inequalities

In this paper we deal with the existence theory for a problem and give the proof of the existence by a penalty argument. We shall treat the problem for a variational inequality by introducing the penalized differential equation and then taking the limits of the equation resulting from the penalized approximation. We also discuss the error estimate for the difference of the two solutions in an appropriate norm.     

Experimental observation of superradiance in the stimulated scattering of an intense microwave pump wave by a counterpropagating subnanosecond high-current relativistic electron bunch

The generation of ultrashort superradiant pulses in the stimulated scattering of an intense microwave (38 GHz) pump wave by a counterpropagating high-current relativistic electron bunch has been observed. Scattered radiation is a single ～200-ps pulse with a peak power of about 1 MW. Owing to the Doppler shift of the radiation frequency, frequencies up to 150 GHz are present in the spectrum of the scattered pulse.     

Isolation,characterization, and quantification of curcuminoids and their comparative effects in cerebral ischemia

The study reports a rapid and short analytical technique for separation, characterization, and quantitation along with comparative pharmacological effect of curcuminoids in cerebral ischemia. Flash chromatography, using silica and diol columns along with gradient mobile phase, was utilized to separate three curcuminoids, i.e., curcumin (Cur), demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC) for the first time. The separated peaks were monitored at 200–360?nm, whereas the purity of compounds (96.2–97.6%) was determined through qualitative analysis such as infrared and ¹H and ¹³C-nuclear magnetic resonance spectroscopy, mass spectrometry (MS), and differential scanning calorimetry. Furthermore, chitosan nanoparticles (CS-NPs) for curcuminoids were prepared and characterized through zeta sizer, zeta potential, scanning electron microscopy, and transmission electron microscopy. The developed ultra performance of liquid chromatography-electrospray ionization-quadrupole-time of flight-mass spectrometry/mass spectrometry (UPLC-ESI-Q-TOF-MS/MS) method showed simplified automation and shorter run time for Combi flash over conventional separation techniques. The CS-NPs for all the three curcuminoids and combined-curcuminoids (CCr) (combined and administered together for a synergistic effect), following intranasal administration in middle cerebral artery–occluded rats were evaluated for grip strength, locomotor activity, and histopathological examination where the anti-ischemic activity was observed, in terms of potency, for all three CS-NPs and CCr as CCr>Cur>DMC>>BDMC. Cur-CS-NPs exhibited more potency among Cur, DMC, and BDMC, whereas CCr was the more potent anti-ischemic drug compared to Cur, DMC, and BDMC. For Cur the characteristic activity is proposed because of the presence of methoxy group on the phenyl ring whereas for CCr it is synergistic effect of curcuminoids.     

On symmetrized stochastic convexity and the inequalities of Hermite–Hadamard type

Aequationes mathematicae - In this paper the concept of symmetrized convex stochastic processes is introduced. Some characterizations involving Hermite–Hadamard type inequalities and a...