Effects of time on the magnetic properties of terbium-doped LaMnO3

The magnetic properties of the perovskite form of LaMnO₃ have been shown strong interest in recent years due to its high potential for use in magnetic devices. In this paper, the magnetic properties of a 30% terbium-doped LaMnO₃ (LMTO) perovskite manganite synthesized by a conventional solid-state reaction were investigated. Data on these properties was recorded periodically via SQUID and VSM to reveal it to be best described magnetically as a spin glass system. Thus, the time effect must be taken into consideration in instantaneously determining this material’s spin glass state as well as the overall magnetic properties in the absence of a magnetic field. The results of this paper point to a more in-depth understanding of the change in magnetic properties associated with doped LaMnO₃.     

Corrigendum to “Highly effective and enantioselective phospho-Aldol reaction of diphenyl phosphite with N-alkylated isatins catalyzed by quinine” [Tetrahedron Lett. 52 (2011) 1157-1160]

In our recent published Letter entitled ‘Highly effective and enantioselective Phospho-Aldol reaction of diphenyl phosphite with N-alkylated isatins catalyzed by quinine’, there was an inaccurate structural determination of the final product. We report here the correction of the structure via X-ray diffraction of the single crystal. The product should be α-oxindole-phosphonate, which was derived from the subsequent phospha-Brook rearrangement of the normal phospho-Aldol product.     

Global weak solutions for a two-component Camassa-Holm shallow water system

In this paper, we prove the existence of global weak solution for an integrable two-component Camassa-Holm shallow water system provided the initial data satisfying some certain conditions.     

Ring-Opening Polymerization of γ-(4-Vinylbenzyl)-(L)-Glutamate N-Carboxyanhydride for the Synthesis of Functional Polypeptides

Introducing various pendant functional groups and building blocks of interest to polypeptides in a highly efficient, controlled manner is crucial to access polypeptide materials with desired structures and functions. In this study, we synthesized γ-(4-vinylbenzyl)-(L)-glutamate N-carboxyanhydride (VB-Glu-NCA), which was readily obtained and purified in large quantity. VB-Glu-NCA monomer was subsequently used for the synthesis of polypeptides containing conjugation-amenable, pendant vinyl functional groups. Controlled, living polymerizations of VB-Glu-NCA were achieved by using hexamethyldisilazane (HMDS) as the initiator, catalytic amounts of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the co-catalyst, and nitrobenzene as the inhibitor of radical-induced side reactions on the vinyl group of VB-Glu-NCA. The resulting poly(γ-(4-vinylbenzyl)-(L)-glutamate) (PVBLG) gave rise to polypeptides containing pendant functional groups or moieties through various vinyl chemistries.     

电阻传感器信号测量的自校正方法

本文介绍了电阻传感器在信号测量中采用自校正技术的测量方法     

Structural investigations of nanocrystalline Ti–Al and Ni by PAC

Nanocrystalline Ti-Al and Ni are investigated on an atomic scale by perturbed γγ-angular correlation spectroscopy in combination with X-ray diffraction. Ti-Al compounds produced by mechanical alloying consist of disordered solid solutions. Annealing of the samples effects a transformation into ordered intermetallic compounds, which is observed via the occurrence of characteristic electric field gradients. The local magnetic properties of nanocrystalline Ni, produced by pulsed electrodeposition, are investigated. Besides the local magnetic field known from polycrystalline Ni, a second component is detected, which is attributed to a magnetic perturbation due to grain boundaries. The width of this magnetic boundary is estimated to 3–4 nm. This revised version was published online in August 2006 with corrections to the Cover Date.     

Lelong numbers,complex singularity exponents,and Siu's semicontinuity theorem

In this note, we describe a relation between Lelong numbers and complex singularity exponents. As an application, we obtain a new proof of Siu's semicontinuity theorem for Lelong numbers.     

Rate effect and coupled evolution of atomic motions and potential landscapes

Since rate effect of materials plays a key role in impact engineering, the microscopic mechanism of rate effect is investigated at molecular level in this paper. The results show that rate effect on the strength of atomic system is closely related to the coupled evolution of atomic motions and potential landscapes. Accordingly, it becomes possible to develop a new algorithm of molecular simulation, which could properly and efficiently demonstrate strain rate effect under a wide range of loading rates and unveil the mecha- nisms underlying the strain rate effects.