广义加权极大Morrey空间中次线性算子的有界性质

该文给出定义在R~n上的一类广义加权极大Morrey空间.证明一类次线性算子,包括分数次积分算子,在该类空间中的有界性质.同时还研究该类次线性算子的交换子在广义加权极大Morrey空间中的有界性质.     

Fermionic-mode entanglement in non-Markovian environment

We evaluate the non-Markovian effects on the entanglement dynamics of a fermionic system interacting with two dissipative vacuum reservoirs. The exact solution of density matrix is derived by utilizing the Feynman–Vernon influence functional theory in the fermionic coherent state representation and the Grassmann calculus, which are valid for both the fermionic and bosonic baths, and their difference lies in the dependence of the parity of the initial states. The fermionic entanglement dynamics is presented by adding an additional restriction to the density matrix known as the superselection rules. Our analysis shows that the usual decoherence suppression schemes implemented in qubits systems can also be achieved for systems of identical fermions, and the initial state proves its importance in the evolution of fermionic entanglement. Our results provide a potential way to decoherence controlling of identical fermions.     

Predicting Polymorphism of Electrospun Polyvinylidene Fluoride Membranes by Their Morphologies

Although electrospinning of polyvinylidene fluoride (PVDF) has been studied for more than 10 years, the crystalline phase differentiation of the electrospun mats is still normally through the combination of different characterization techniques, and the relationship between polymorphism and morphology of the fibers in electrospun PVDF membranes has never been reported. Here, we show their close relationships by conducting room-temperature electrospinning experiments on various polymer/solvent systems. The electrospun membranes full of bead-free fibers have a very high fraction of β-phase, F(β), over 90%, and high orientation, whereas the membranes comprising beads and/or a large number of beaded fibers most often result in a low fraction of β-phase (F(β) normally below 50%) and low orientation. On the other hand, electrospun membranes consisting of both bead-free fibers and a very limited number of beaded fibers showed a medium high fraction of β-phase, F(β) more than 70% but less than 90%. These findings suggest the feasibility of intuitively predicting the crystalline phase of electrospun PVDF membranes directly by their morphologies, which is obviously simple, inexpensive and convenient for future investigations.     

Self-Assembly of Trisiloxane-Tailed Sugar Surfactant in Aqueous Solution

Abstract

A lactobionamide-based trisiloxane surfactant (Si3N2–LA) was prepared via a two-step method. Structure characterization of Si3N2–LA was performed by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (¹H NMR). Surface activity and aggregation behavior in aqueous solution of Si3N2–LA were investigated by surface tension measurements, dynamic light scattering (DLS) and negative-stained transmission electron microscopy (TEM). The results show that the surfactants can self-assemble into spherical vesicles with diameters in the range from 50 to 150 nm due to the introduction of trisiloxane tail.     

A Novel Reduction of Azides to Amines with Tellurium Metal in Near-Critical Water

Tellurium metal in near-critical water (275°;C) provides a novel and efficient method for the reduction of azides, producing amines in good yields.     

SUBSTITUTED 4,5-DIOXO-1,3-DIAZA-2λ3,4λ4-DIPHOSPHOLANE AND RELATED COMPOUNDS

Abstract

Cyclization of 1 with 2 yielded the title compound 3, which was transformed into the corresponding 1,3,2,4-diazadiphospholanes 4 and 5 by using DMSO or sulfur respectively. The addition reaction of 3 with butanedione gave 3,4-di-oxo-1-phenyl-2,5-diaza-6,9-dioxa-1λ⁵,3λ⁴-diphosphaspiro[4,4]nonane 6. The structures of 3, 4 and 5 were confirmed by elemental analysis, IR, NMR and GC-MS. Although 6 could not be isolated in pure form because of its rapid decomposition, the ₃₁P NMR data indicated its existence. It was found that there were cis- and trans-isomers in 3, 4, 5 and 6.     

STUDIES ON ORGANOPHOSPHORUS COMPOUNDS XXX. MASS SPECTROSCOPIC INVESTIGATION OF 2-ALKYL-2-OXO-1,3,2-DIOXA-PHOSPHORINANE AND-PHOSPHEPANE

Abstract

The mass spectra of 2-alkyl-2-oxo-1,3,2-dioxa-phosphorinane and-phosphepane showed that the ring opening was in competition with the cleavage of the P[sbnd]C bond. According to the fragmentation pathway, which was dependent on the structure of exocyclic substituents on phosphorus, the 2-alkyl-2-oxo-1,3,2-di-oxa-phosphorinanes can be classified in two categories. The main process in category A was the ring opening and/or C[sbnd]C bond cleavage. While in category B the cleavage of P[sbnd]C bond was predominant. However, for 2-alkyl-2-oxo-1,3,2-dioxa-phosphepane. no matter how the structure of 2-alkyl group was, the ring opening was a dominant process.     

Gas-Phase Reactivity of Peptide Thiyl (RS•), Perthiyl (RSS•), and Sulfinyl (RSO•) Radical Ions Formed from Atmospheric Pressure Ion/Radical Reactions

In this study, we demonstrated the formation of gas-phase peptide perthiyl (RSS?) and thiyl (RS?) radical ions besides sulfinyl radical (RSO?) ions from atmospheric pressure (AP) ion/radical reactions of peptides containing inter-chain disulfide bonds. The identity of perthiyl radical was verified from characteristic 65 Da (?SSH) loss in collision-induced dissociation (CID). This signature loss was further used to assess the purity of peptide perthiyl radical ions formed from AP ion/radical reactions. Ion/molecule reactions combined with CID were carried out to confirm the formation of thiyl radical. Transmission mode ion/molecule reactions in collision cell (q2) were developed as a fast means to estimate the population of peptide thiyl radical ions. The reactivity of peptide thiyl, perthiyl, and sulfinyl radical ions was evaluated based on ion/molecule reactions toward organic disulfides, allyl iodide, organic thiol, and oxygen, which followed in order of thiyl (RS?) > perthiyl (RSS?) > sulfinyl (RSO?). The gas-phase reactivity of these three types of sulfur-based radicals is consistent with literature reports from solution studies.