在分子自旋量子系统中的可控多体纠缠态

在由N＋1个相互作用的反铁磁分子环构成的量子自旋系统中,可以调控1种多体纠缠态。N个周边分子环的电子自旋和1个中心分子环的电子存在相互交换,从而在分子间形成可调的相互作用。通过整个系统的有效自旋哈密顿量解析得出系统的量子动力学行为。研究发现在量子涨落的条件下,1种高精度的形纠缠态可以被制备出来。通过控制分子间的相互作用,这种多体纠缠态也可以从一些分子环传输到其他分子环上。     

支化高分子链穿孔行为的研究

采用Langevin dynamics 方法对支化高分子链的穿孔行为进行了研究.通过研究一条高分子链上各个单体的进孔时间来判断支点的位置,从而预测出支化高分子链的支链位置.模拟研究发现：支化高分子链的平均穿孔时间τ与主链的长度N满足标度关系τ~N^α,其中标度系数α随着外场力F的增大而增大.同时还研究了支链数n对穿孔时间的影响,发现标度系数α的值随着n的增大有减小的趋势.通过对支化高分子链穿孔行为的研究从而加深对生物大分子穿孔行为的了解.     

Mean-field and high temperature series expansion calculations of some magnetic properties of Ising and XY antiferromagnetic thin-films

In this work,the magnetic properties of Ising and XY antiferromagnetic thin-films are investigated each as a function of N’eel temperature and thickness for layers(n = 2,3,4,5,6,and bulk(∞)) by means of a mean-field and high temperature series expansion(HTSE) combined with Pad’e approximant calculations.The scaling law of magnetic susceptibility and magnetization is used to determine the critical exponent γ,ν eff(mean),ratio of the critical exponents γ/ν,and magnetic properties of Ising and XY antiferromagnetic thin-films for different thickness layers n = 2,3,4,5,6,and bulk(∞).     

Avidin conjugation to up-conversion phosphor NaYF4:Yb3+, Er3+ by the oxidation of the oligosaccharide chains

NaYF₄:Yb³⁺, Er³⁺ nanoparticles were successfully prepared by a polyol process using diethyleneglycol (DEG) as solvent. After being functionalized with SiO₂–NH₂ layer, these NaYF₄:Yb³⁺, Er³⁺ nanoparticles can conjugate with activated avidin molecules (activated by the oxidation of the oligosaccharide chain). The as-formed NaYF₄:Yb³⁺, Er³⁺ nanoparticles, NaYF₄:Yb³⁺, Er³⁺ nanoparticles functionalized with amino groups, avidin conjugated amino-functionalized NaYF₄:Yb³⁺, Er³⁺ nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR), UV/Vis absorption spectra, and up-conversion luminescence spectra, respectively. The biofunctionalization of the NaYF₄:Yb³⁺, Er³⁺ nanoparticles has less effect on their luminescence properties, i.e., they still show the up-conversion emission (from Er³⁺, with ⁴S_3/2 → ⁴I_15/2 at ~540 nm and ⁴F_9/2 → ⁴I_15/2 at ~653 nm), indicative of the great potential for these NaYF₄:Yb³⁺, Er³⁺ nanoparticles to be used as fluorescence probes for biological system.     

Crystal and magnetic structure of single-crystal La<Subscript>1-x</Subscript><Emphasis Type="Bold">Sr</Emphasis><Subscript>x</Subscript><Emphasis Type="Bold">MnO</Emphasis><Subscript>3</Subscript><Emphasis Type="Bold">(x ≈ 1/8)</Emphasis>

A neutron powder diffraction (NPD) study on the crystal and magnetic structure of a crushed La_1-xSr_xMnO₃ (x ≈ 1/8) single crystal has been performed. The sample belongs to orthorhombic (Pnma, O) above the Jahn-Teller (JT) transition temperature (T_JT) and monoclinic (P12₁/c1, M^′) in the JT regime. We have also refined the NPD data below the charge/orbital ordering (CO/OO) temperature (T_CO/OO) with a monoclinic (P12₁/c1, M^′′) model because the experimental resolution was insufficient to clearly identify a triclinic structure. The refined lattice parameters show an obvious breathing-mode distortion between T_CO/OO and T_JT, accompanied by a large deviation of the monoclinic angle β from 90°, signifying a very strong cooperative JT distortion. A ferromagnetic (FM) moment of 3.43(5)μ _B/Mn besides an A-type antiferromagnetic (A-AFM) moment of 0.54(2) μ _B/Mn is directed mainly along the b axis in P12₁/c1 symmetry at 5 K. With increasing temperature, the A-AFM domains transform into FM ones above ~100 K and the FM spin orientation turns from the b to the c axis in crystallographic b-c plane below T_c = 187(1) K. The magnetization measurements show typical anomalies around T_CO/OO and T_JT. The measured saturation moment of 3.9(1)μ _B/Mn at 70 kOe and 5 K is well consistent with the sum 3.97(5)μ _B/Mn of the refined FM and A-AFM moments at 5 K, implying the A-AFM spins are aligned in field direction at 70 kOe. The applied magnetic field can affect the paramagnetic insulating (PMI) state in the range of magnetic polarons. Based on the size of JT distortion and the bond-valence sums (BVS’s), the CO/OO phenomenon is being discussed.     

硫化汞纳米组装链的诱导合成及其光学性能

选择一种高活性模板剂通过简单的诱导组装工艺, 合成了结构均一有序的硫化汞一维纳米组装链, 该纳米链由直径约为30 nm的粒子组装而成, 长度约0.6-1.0 μm. 通过XRD、TEM、FT-IR、UV-Vis光谱等手段对产物结构进行了表征. UV-Vis实验结果发现, 产物具有良好的紫外吸收性能. 产物对荧光素具有灵敏的荧光猝灭效应, 预计在微观修饰、纳米器件、样品检测等领域具有潜在的应用价值. 同时还对产物的形成机理做了初步探讨.     

含长碳链间隔臂结构的强碱性阴离子交换树脂的合成及热稳定性

研究了一种含长碳链间隔臂结构的强碱性阴离子交换树脂的新合成方法.评价了该树脂在水中的热稳定性.结果表明,以苯乙烯-二乙烯基苯共聚白球和1,3-噁嗪-2-酮为原料,季铵型离子液体为催化剂,得到带有胺丙基的苯乙烯-二乙烯基苯共聚珠体,再用甲酸和甲醛N-甲基化,溴乙烷季铵化,可以生成强碱交换量为1.86mmol/g强碱阴离子交换树脂.含长碳链间隔臂结构的OH~-型阴离子交换树脂在100℃去离子水中保持720h交换量仅下降11.83%,好于商业通用的强碱阴离子交换树脂.     

Synthesis and photovoltaic properties of poly(p-phenylenevinylene) derivatives with two triphenylamine and bithiophene conjugated side chains

Two soluble poly(p-phenylenevinylene) derivatives (PPVs) with two bithiophenes as conjugated side chains, P1 and P2, were synthesized and characterized for application in polymer solar cells (PSCs). The thermal, photophysical, electrochemical and photovoltaic properties of the PPVs were investigated and compared with those of the PPVs without conjugated side chains. Bulk heterojunction solar cell devices are fabricated using the copolymers as the electron donor and PCBM ([6,6]-phenyl-C₆₁-butyric acid methyl ester) as the electron acceptor. The power conversion efficiencies (η) based on the P1 and P2 are 1.1% and 1.41% under AM 1.5 illumination (100 mW/cm²), respectively.     

1-D Open-channeled 3-D Supramolecular Frameworks Built with 2,3-Dihydroxybutanedioic Acid (H4dhbd) and 2,2':6,2"-Terpyridine (tpy)

The complex [Cu2(H2dhbd)2(tpy)2]·CH3OH·4H2O1 (H4dhbd=2,3-dihydroxybutane-dioic acid, tpy=2,2":6',2"-terpyddine) has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis. The crystal is of triclinic, space groups P1 with a=8.6859(17), b=11.223(2), c=12.275(2)A,α=112.454(3), β=98.435(3),γ=105.593(3)°, V=1022.5(3) A3, Z=1, C38H42Cu2N6.O18, Mr=997.86, Dc=1.621 g/cm3,μ=1.127 mm-1, F(000)=514, T=293(2) K, the final R=0.0539 and wR=0.1394 for 3550 observed reflections with 1 >20(1). In the dinuclear unit, two CuⅡ atoms are bridged by two H2dhbd chelate anions, forming a 14-membered ring, in which the distance of Cu…Cu atoms is 7.0526(12)A. Adjacent dinuclear units are constituted through π-π interactions and C-H…O hydrogen-bonding interactions, fashioning the final 3-D supramolecular framework with 1-D open channels. Variable-temperature magnetic susceptibility measurement indicates the presence of weak antiferromagnetic exchange interactions between CuⅡ ions.     

Approximate analysis and optimization of batch ordering policies in capacitated supply chains

Devising manufacturing/distribution strategies for supply chains and determining their parameter values have been challenging problems. Linking production management to stock keeping processes improves the planning of the supply chain activities, including material management, culminating in improved customer service levels. In this study, we investigate a multi-echelon supply chain consisting of a supplier, a plant, a distribution center and a retailer. Material flow between stages is driven by reorder point/order quantity inventory control policies. We develop a model to analyze supply chain behavior using some key performance metrics such as the time averages of inventory and backorder levels, as well as customer service levels at each echelon. The model is validated against simulation, yielding good agreement of robust performance metrics. The metrics are then used within an optimization framework to design the supply chain so as to minimize expected total system costs. The outcome of the optimization framework specifies how to move inventory throughout the supply chain and how to set inventory control parameters, i.e., reorder levels and replenishment batch sizes.