1,5—二羟基蒽醌及其稀土配合物的红外光谱研究

利用同位素取代技术,并比较1,5-二羟基蒽醌及其稀土配合物的光谱变化,归属了它们的红外吸收带。确认了Ln—O键的特征带,分析了配位键的性质。     

对大学物理实验课程的两点考虑

本文根据目前大学物理实验课程有待改革的实际情况，在研究了传统教法的基础上，参照一些前辈对改革的意见，提出了自己对大学物理实验的两点想法。     

Calibration of optical tweezers based on acousto-optic deflector and field programmable gate array

Accurate calibrations of stiffness and position are crucial to the quantitative measurement with optical tweezers. In this paper, we present a new calibration scheme for optical tweezers including stiffness and position calibrations. In our system, acousto-optic deflectors (AODs) are used as laser beam manipulating component. The AODs are controlled by a field programmable gate array (FPGA) connected to a computer using universal serial bus (USB) communication mode. Our results agree well with the present theory and other experimental results.     

Preparation and cell response of bio-mineralized Fe3O4 nanoparticles

Silk fibroin (SF)-coated Fe(3)O(4) nanoparticles (NPs) with good superparamagnetism were successfully prepared via a bio-mineralization process at room temperature. Two cell tests revealed that mineralized SF-coated Fe(3)O(4) NPs presented good cytocompatibility for L929 and osteoblast cells and higher cell density after 5 d with high concentrations of SF-coated Fe(3)O(4) NPs (up to 0.5 mg/mL). These resulted from SF surface coating on NPs, nano-surface morphology and iron ion release of Fe(3)O(4) NPs. The mineralized SF-coated Fe(3)O(4) NPs could be envisioned for various bone orthopedic and therapeutic applications, in which SF-coated NPs location is controlled through an external magnetic field to promoted bone growth.     

Preparation of PLLA/PLGA microparticles using solution enhanced dispersion by supercritical fluids (SEDS).

In this work, poly(L-lactic acid)/poly(lactide-co-glycolide) (PLLA/PLGA) microparticles were prepared using the technique of solution-enhanced dispersion by supercritical fluids (SEDS). For comparison, separate PLLA and PLGA microparticles were also produced by the same SEDS process. The produced microparticles were characterized by scanning electron microscopy, laser particle size analyzer, X-ray diffraction, differential scanning calorimetry, Fourier transform infrared spectroscopy, and gas chromatography. Results indicate that PLLA/PLGA microparticles possess sphere-like shapes with smooth surfaces. The mean particle size of PLLA/PLGA microparticles ranges from 1.76 to 2.15 microm, depending on the feeding ratio of PLLA to PLGA used in the SEDS process. The crystallinity of PLLA/PLGA microparticles decreases after the SEDS processing, so that the produced microparticles are in an amorphous state. Pure PLGA was hard to precipitate in small, fine microparticle form without the presence of PLLA. A model drug, paclitaxel, was encapsulated into PLLA/PLGA microparticles by the same SEDS process, and the in vitro release rate of paclitaxel from these PLLA/PLGA composites could be modulated by variation of the mixing ratio PLLA:PLGA. The prepared microparticles have negligible residual organic solvent. Drug-loaded PLLA/PLGA microparticles produced by SEDS have potential as an advanced colloidal suspension for pharmaceutical applications.     

Toxicological effect of ZnO nanoparticles based on bacteria

Streptococcus agalactiae and Staphylococcus aureus are two pathogenetic agents of several infective diseases in humans. Biocidal effects and cellular internalization of ZnO nanoparticles (NPs) on two bacteria are reported, and ZnO NPs have a good bacteriostasis effect. ZnO NPs were synthesized in the EG aqueous system through the hydrolysis of ionic Zn2+ salts. Particle size and shape were controlled by the addition of the various surfactants. Bactericidal tests were performed in an ordinary broth medium on solid agar plates and in liquid systems with different concentrations of ZnO NPs. The biocidal action of ZnO materials was studied by transmission electron microscopy of bacteria ultrathin sections. The results confirmed that bactericidal cells were damaged after ZnO NPs contacted with them, showing both gram-negative membrane and gram-positive membrane disorganization. The surface modification of ZnO NPs causes an increase in membrane permeability and the cellular internalization of these NPs whereas there is a ZnO NP structure change inside the cells.     

Toeplitz operators with unbounded symbols of several complex variables

In this note we construct a function φ in L²(Bn,dA) which is unbounded on any neighborhood of each boundary point of Bn such that Tφ is a trace class operator on Bergman space for several complex variables. In addition, we also discuss the compactness of Toeplitz operators with L¹ symbols.     

Cation⊗3π: cooperative interaction of a cation and three benzenes with an anomalous order in binding energy

Cation-π or cation-π-π interaction between one cation and one or two structures bearing rich π-electrons (such as benzene, aromatic rings, graphene, and carbon nanotubes) plays a ubiquitous role in various areas. Here, we analyzed a new type interaction, cation?3π, whereby one cation simultaneously binds with three separate π-electron-rich structures. Surprisingly, we found an anomalous increase in the order of the one-benzene binding strength of the cation?3π interaction, with K(+) > Na(+) > Li(+). This was at odds with the conventional ranking of the binding strength which usually increases as the radii of the cations decrease. The key to the present unexpected observations was the cooperative interaction of the cation with the three benzenes and also between the three benzenes, in which a steric-exclusion effect between the three benzenes played an important role. Moreover, the binding energy of cation?3π was comparable to cation?2π for K(+) and Na(+), showing the particular importance of cation?3π interaction in biological systems.