Microwave-Responsive Flexible Room-Temperature Phosphorescence Materials Based on Poly(vinylidene fluoride) Polymer

The development of flexible, room-temperature phosphorescence (RTP) materials remains challenging owing to the quenching of their unstable triplet excitons via molecular motion. Therefore, a polymer matrix with T_g higher than room temperature is required to prevent polymer segment movement. In this study, a RTP material was developed by incorporating a 4-biphenylboronic acid (BPBA) phosphor into a poly(vinylidene fluoride) (PVDF) matrix (T_g=−27.1 °C), which exhibits a remarkable UV-light-dependent oxygen consumption phosphorescence with a lifetime of 1275.7 ms. The adjustable RTP performance is influenced by the crystallinity and polymorph (α, β, and γ phases) fraction of PVDF, therefore, the low T_g of the PVDF matrix enables the polymeric segmental motion upon microwave irradiation. Consequently, a reduction in the crystallinity and an increase in the α phase fraction in PVDF film induces RTP after 2.45 GHz microwave irradiation. These findings open up new avenues for constructing crystalline and phase-dependent RTP materials while demonstrating a promising approach toward microwave detection.     

Efficient racemization of 1-phenylethylamine and its derivatives

We report on simple and efficient procedure for the racemization of 1-phenylethylamine and its derivatives. In the presence of trichloroisocyanuric acid, N-chloroimine derivative is formed as the intermediates, with subsequent hydrogenation catalyzed by Pd-C leading to the racemic product.     

Maximizing DR-submodular+supermodular functions on the integer lattice subject to a cardinality constraint

Journal of Global Optimization - Arising from practical problems such as in sensor placement and influence maximization in social network, submodular and non-submodular maximization on the integer...     

重离子碰撞中熔合位垒的研究

熔合位垒的研究对熔合反应以及超重核合成有重要的意义。在改进的同位旋相关的量子分子动力学(ImIQMD)模型框架下,提取了熔合反应体系40Ca+40Ca,48Ca+208Pb,48Ca+204Pb和16O+154Sm的熔合位垒。研究了壳修正能对熔合位垒的影响、动力学位垒的能量依赖性、同位旋效应以及形变核的方向效应。计算发现壳修正能降低了熔合反应的位垒。在研究动力学位垒的能量依赖性时,发现位垒高度和位垒半径表现出相反的能量依赖行为。在动力学反应中,当两个核距离接近时,缺中子体系的库仑势同样表现出一定的能量依赖性。对于丰中子体系,由于中子屏蔽作用,库仑势基本没有能量依赖性。     

A lateral flow biosensor for detection of single nucleotide polymorphism by circular strand displacement reaction

A lateral flow biosensor for detection of single nucleotide polymorphism based on circular strand displacement reaction (CSDPR) has been developed. Taking advantage of high fidelity of T4 DNA ligase, signal amplification by CSDPR, and the optical properties of gold nanoparticles, this assay has reached a detection limit of 0.01 fM.     

Determination of tobacco-specific N-nitrosamines in rabbit serum by capillary zone electrophoresis and capillary electrophoresis-electrospray ionization-mass spectrometry with solid-phase extraction

In this paper, we propose a new strategy for separation and determination of tobacco-specific N-nitrosamines (TSNAs), a group of strong carcinogens found only in tobacco products, by using CZE and CE-MS associated with SPE. Six TSNAs: N'-nitrosonornicotine, N'-nitrosoanatabine, N'-nitrosoanabasine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol, and 4-(methylnitrosamino)-4-(3-pyridyl)-1-butanol were simultaneously separated by either of two CZE methods, one of which worked with ammonium formate buffer (pH 2.5) and another with citrate buffer (pH 2.4), as well as a CE-MS method. The CZE conditions including pH and concentration of running buffer, capillary length, applied voltage, and capillary temperature were systematically optimized. For CE-MS method, an optimized sheath liquid consisted of methanol-water was used at a flow rate of 10 muL/min. With SPE procedure, our proposed CE-MS method was successfully applied to determine TSNAs after 15 min metabolism in rabbits. A comparison study between CZE and CE-MS methods for quantitative purposes was carried out, showing that both methods provided similar separation efficiency, selectivity, repeatability, linearity, and recovery. However, CE-MS method was better suited for the analysis of TSNAs in complicated biological samples for its sensitivity and extra information on molecular structure. Having good accordance with our previous work by using LC-MS, the new CE-MS method is expected to be an alternative to the LC-MS method and applied to study the metabolism of TSNAs.     

Oxidation of Alkynyl Boronates to Carboxylic Acids,Esters, and Amides

A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)−B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation. Notably, amino acids and peptides can be used as nucleophiles, providing an efficient method for the synthesis and modification of peptides. The practicability of this methodology was further highlighted by the preparation of pharmaceutical molecules.     

A 4-hydroxynaphthalimide-derived ratiometric fluorescent chemodosimeter for imaging palladium in living cells

A highly selective ratiometric fluorescent chemodosimeter derived from 4-hydroxynaphthalimide was designed and synthesized to image palladium species in living cells by virtue of a palladium-catalyzed depropargylation reaction, and it could monitor three typical palladium species (0, + 2 and + 4) without additional reagents.     

Theoretical studies of furoxan-based energetic nitrogen-rich compounds

Density functional theory calculations were performed to study the effects of different substituents and nitrogen-containing heterocyclic rings on the heats of formation (HOFs), energetic properties, and thermal stability for a series of furoxan derivatives. The isodesmic reaction method was employed to calculate the HOFs of the derivatives using total energies obtained from electronic structure calculations. The detonation velocities and pressures were evaluated by using the semiempirical Kamlet–Jacobs equations, based on the theoretical densities and HOFs. The bond dissociation energies and bond orders for the weakest bonds were analyzed to investigate the thermal stability of the furoxan derivatives. These results provide basic information for the molecular design of novel high energy density materials.