Preparation of pillared layered antimony hydroxide and its flame retardancy in thermoplastic polyurethane

Journal of Thermal Analysis and Calorimetry - In this article, a pillared layered antimony hydroxide (Sb-LH) material has been prepared by the hydrothermal method. X-ray diffraction,...     

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.     

One-step method for preparing the experimental pure state in nuclear magnetic resonance

Quantum computing is an emerging and promising research field in modern quantum physics and is committed to accelerating traditional calculation processes using the principle of quantum mechanics[1,2].Several computation models have been proposed,including the circuit model[3],topologic quantum computation[4],adiabatic quantum computing[5],and duality quantum computing[6-8].Universal quantum computation generally includes a system initialization,evolutionary control,and a final-state readout[9],where the preparation of the initial state is a key step in the entire process.     

Catalytic benzene mono-alkylation over three catalysts: improving activity and selectivity with M-Y catalyst

Modified Y type catalyst (M-Y) shows great potential for the preparation of toluene attribute to catalyst topology and synergistic effect of Lewis acid and Brönsted acid in the alkylation reaction. However, it still remains a big challenge to build a reaction mechanism. Thereby, based on the study of HZSM-5, H-beta and M-Y catalysts structure and physical properties, a plausible reaction mechanism was proposed. The samples were characterized by X-ray diffraction, N₂ adsorption/desorption, Fourier transform infrared absorption spectra and Pyridine adsorption infrared. The activity of catalysts was tested in benzene alkylation with methanol and was found to be in the following increasing order: Na-Y (no effect)?<?H-Y?<<?HZSM-5?<?H-beta?<?M-Y.     

Offline Arbitrated Quantum Blind Dual-Signature Protocol with Better Performance in Resisting Existential Forgery Attack

In this paper, we present an offline arbitrated quantum blind dual-signature protocol by using four-particle entangled Greenberger-Horne-Zeilinger(GHZ) states. By using the special relationship of four-particle GHZ states, we can not only support the security of quantum signature, but also guarantee the anonymity of the message owner. In our protocol, the authority of the arbitrator has been reduced, i.e., he will not help the receiver verify the signature in the verification. Compared with the previous quantum blind signature protocols, the presented arbitrator is offline. Finally, the security analysis and discussion are proposed.     

Semidiscrete finite element Galerkin approximations to the equations of motion arising in the Oldroyd model

In this paper, a semidiscrete finite element Galerkin methodfor the equations of motion arising in the 2D Oldroyd modelof viscoelastic fluids with zero forcing function is analysed.Some new a priori bounds for the exact solutions are derivedunder realistically assumed conditions on the data. Moreover,the long-time behaviour of the solution is established. By introducinga Stokes–Volterra projection, optimal error bounds forthe velocity in the L(L²) as well as in the L(H¹)-norms andfor the pressure in the L(L²)-norm are derived which are validuniformly in time t > 0.     

New results on quadratic stabilization of switched linear systems with polytopic uncertainties

^** Corresponding author. Email: longwang{at}pku.edu.cn^*** Email: jizj{at}mech.pku.edu.cn In this paper, the quadratic stabilization of switched linearsystems with polytopic uncertainties is considered. Comparedwith the existing result, a more general switching control methodis proposed to guarantee the quadratic stabilization. This switchingcontrol method is based on the partition of the vertex matrixset of each subsystem. By this method, the matrix inequalitiesneeded to be solved are always less than those needed to besolved before except one extreme case; for this case, it isequal. The switched control synthesis problem is also studiedfor both switched state feedback and output feedback. Severalbilinear matrix inequality based conditions are derived forboth cases.     

On sums of powers of inverse complete quotients

For an irrational number , let denote its -th continued fraction inverse complete quotient, obtained by deleting the first partial quotients. For any positive real number , we establish the optimal linear bound on the sum of the -th powers of the first complete quotients. That is, we find the smallest constants such that for all and all irrationals .