Surface plasmonic resonance sensor by metal strip pair arrays

We present a surface plasmonic resonance sensor composed of Ag strip pairs array embedded in the background material. The calculated results demonstrate that one of the transmission dips of the structure is very sensitive to the background materials. Meanwhile, the structure could achieve the sensitivity (nm/RIU) about 700 nm/RIU, when the slits width of Ag strip pairs is 10 nm.     

双核Ni（Ⅱ）氯醌酸阴离子桥联配合物的合成和磁性

合成了4种以氯醌酸阴离子为桥联配体的Ni(Ⅱ)单核和双核配合物,经元素分析、IR、电子光谱、磁化率测定进行了表征。发现其μeff值随温度降低先出现极大,后又复变小。在考虑到分子间相互作用和单离子零场分裂影响等因素后,用修正的Heisenberg模型进行处理,结果表明分子内Ni(Ⅱ)离子间存在铁磁性磁交换作用,而分子间则为反铁磁性磁交换作用。     

Label free DNA detection based on gold nanoparticles quenching fluorescence of Rhodamine B

A novel and sensitive label free DNA detection method using gold nanoparticles (GNPs) and Rhodamine B (RB) has been developed. The assay is based on the following two properties. One is the different adsorption properties of single-stranded and double-stranded DNA on GNPs in colloidal solution. The other is the different quenching ability of aggregated GNPs and dispersed GNPs on RB. Un-aggregated GNPs could effectively quench the fluorescence of RB. However, the quenching ability greatly decreases after GNPs aggregated. The hybridization of probe DNA and target DNA is monitored by the fluorescence detection after the RB is added to the solution. Under the optimal experimental conditions, the detection limit of this assay is 2.9×10(-13) mol L(-1).     

Numerical investigation on evolution of cylindrical cellular detonation

Cylindrical cellular detonation is numerically investigated by solving two- dimensional reactive Euler equations with a finite volume method on a two-dimensional self-adaptive unstructured mesh. The one-step reversible chemical reaction model is applied to simplify the control parameters of chemical reaction. Numerical results demonstrate the evolution of cellular cell splitting of cylindrical cellular detonation explored in experimentas. Split of cellular structures shows different features in the near-field and far-field from the initiation zone. Variation of the local curvature is a key factor in the behavior of cell split of cylindrical cellular detonation in propagation. Numerical results show that split of cellular structures comes from the self-organization of transverse waves corresponding to the development of small disturbances along the detonation front related to detonation instability.     

Analysis of the HO2 vibrational spectrum on an accurate ab initio potential energy surface

The complete vibrational spectrum of the HO2(X(2)A' ') radical, up to the H + O2 dissociation limit, has been determined quantum mechanically on an accurate potential energy surface (PES), based on approximately 15000 ab initio points at the icMRCI+Q/aug-cc-pVQZ level of theory. The vibrational states are found to be assignable at low energies but become more irregular as the energy approaches the dissociation limit. However, even at very high energies, regularity still exists, in sharp contrast to earlier results based on the double many-body expansion (DMBE) IV potential. Several Fermi resonances have been identified, and the spectrum is fit with a spectroscopic Hamiltonian. In addition, the vibrational dynamics is analyzed using a periodic orbit approach.     

Ti:sapphire laser pumped high average power laser crystal Nd:GGG with high efficiency output

High-quality neodymium doped GGG laser crystals have been grown by Czochralski (Cz) method. Results of Nd:GGG thin chip laser operating at 1.064 μm pumped by Ti:sapphire laser operating at 808 nm were reported. The slop efficiency was as high as 20%.     

Thermo-induced formation of unimolecular and multimolecular micelles from novel double hydrophilic multiblock copolymers of N,N-dimethylacrylamide and N-isopropylacrylamide

Two novel double hydrophilic multiblock copolymers of N,N-dimethylacrylamide and N-isopropylacrylamide, m-PDMAp-PNIPAMq, with varying degrees of polymerization (DPs) for PDMA and PNIPAM sequences (p and q) were synthesized via consecutive reversible addition-fragmentation chain transfer (RAFT) polymerizations using polytrithiocarbonate (1) as the chain transfer agent (Scheme 1), where PDMA is poly(N,N-dimethylacrylamide) and PNIPAM is poly(N-isopropylacrylamide). The DPs of PDMA and PNIPAM sequences were determined by 1H NMR, and the block numbers, i.e., number of PDMAp-PNIPAMq sequences (n), were obtained by comparing the molecular weights of multiblock copolymers to that of cleaved products as determined by gel permeation chromatography (GPC). m-PDMA42-PNIPAM37 and m-PDMA105-PNIPAM106 multiblock copolymers possess number-average molecular weights (Mn) of 4.62x10(4) and 9.53x10(4), respectively, and the polydispersities (Mw/Mn) are typically around 1.5. Block numbers of the obtained multiblock copolymers are ca. 4, which are considerably lower than the numbers of trithiocarbonate moieties per chain of 1 (approximately 20) and m-PDMAp precursors (approximately 6-7). PDMA homopolymer is water soluble to 100 degrees C, while PNIPAM has been well known to exhibit a lower critical solution temperature (LCST) at ca. 32 degrees C. In aqueous solution, m-PDMA42-PNIPAM37 and m-PDMA105-PNIPAM106 multiblock copolymers molecularly dissolve at room temperature, and their thermo-induced collapse and aggregation properties were characterized in detail by a combination of optical transmittance, fluorescence probe measurements, laser light scattering (LLS), and micro-differential scanning calorimetry (micro-DSC). It was found that chain lengths of PDMA and PNIPAM sequences exert dramatic effects on their aggregation behavior. m-PDMA105-PNIPAM106 multiblock copolymer behaves as protein-like polymers and exhibits intramolecular collapse upon heating, forming unimolecular flower-like micelles above the thermal phase transition temperature. On the other hand, m-PDMA42-PNIPAM37 multiblock copolymer exhibits collapse and intermolecular aggregation, forming associated multimolecular micelles at elevated temperatures. The intriguing aggregation behavior of this novel type of double hydrophilic multiblock copolymers argues well for their potential applications in many fields such as biomaterials and biomedicines.     

Syntheses,crystal structures,and magnetic properties of three coordination polymers based on manganese(II) and 2,6-naphthalenedicarboxylate

Three novel coordination polymers, namely, [Mn(ndc)(bpy)] _n  · n(H₂O) (1), [Mn(ndc)(phen)] _n (2), and [Mn₃(ndc)₃(bpy)₂] _n (3) (H₂ndc = 2,6-naphthalenedicarboxylic acid, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been hydrothermally synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction analysis. Complexes 1–3 exhibit three-dimensional metal-organic frameworks (MOFs); 1 and 2 are assemblies of the same secondary building units (SBUs), linear infinite chains {Mn(CO₂)₂} _n , forming one-dimensional channel, while complex 3 is constructed by trinuclear clusters {Mn₃(CO₂)₆} SBUs. Magnetic properties of complexes 1 and 3 are also discussed with respect to the bridging mode of the carboxylate groups.     

Crystallization Behavior of Modified Polyester with Varied Macromolecular Architecture

Several modified polyesters with varied macromolecular architecture, such as branched poly(ethylene terephthalate) (PET) based on glycerol (GL) from 0.004 to 0.05 mol ratio as a branching agent, blocked and branched poly(butylene terephthalate)‐polyether containing poly(tetramethylene oxide) (PTMO) as soft segment and GL as a branching unit, as well as segmented poly(ethylene terephthalate)‐polyether,were prepared. Their crystallization behavior was studied by differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and polarized optical microscopy (POM). It was found that a small extent of branching may enhance the crystallization of poly(ethylene terephthalate), while high degrees of branching (0.035–0.05) could block the development of crystallization. On the other hand, for even a small extent of incorporation of GL in the more flexible poly(butylene terephthalate)‐polyether chains, no enhanced crystallization was observed; blocking of crystallization from a branching defect may play the main role. The introduction of PTMO in poly(ethylene terephthalate) chains to a small degree facilitated the nucleation and speeded crystallization, but decreased the melting points of the polymers. A small number of nuclei and the greater induction time were found for branched PETs. The spherulities developed in branched PETs were larger and more perfect than those in PET due to less truncation of spherulites resulting from fewer nuclei, whereas the size of spherulities in poly(ethylene terephthalate)‐polyether became smaller with the increase of PTMO.     

硅酸钇晶体的生长、腐蚀形貌和光谱性能研究

本文采用中频感应提拉法成功生长了未掺杂的Y2SiO5(YSO)晶体,经过定向、切割、抛光后得到样品.经过腐蚀后,利用大视场显微镜和扫描电镜在样品表面上观察到了菱形和四边形的位错蚀坑、小角晶界和包裹物等缺陷;测试了经过氢气、空气退火前后,辐照前后YSO晶体的透过谱,结果表明:YSO晶体的吸收边大约在202nm,氢气退火后在200～300nm波段透过率增加,空气退火后透过率显著降低;辐照后,氢气退火的样品在200～500nm波段透过率显著降低.