Extinction Time of a Metapopulation Driven by Colored Correlated Noises

The simplified incidence function model which is driven by the colored correlated noises is employed to investigate the extinction time of a metapopulation perturbed by environments. The approximate Fokker-Planck Equation and the mean first passage time which denotes the extinction time （Tex） are obtained by virtue of the Novikov theorem and the Fox approach. After introducing a noise intensity ratio and a dimensionless parameter R = D /α （D and a are the multiplicative and additive colored noise intensities respectively）, and then performing numerical computations, the results indicate that： （i） The absolute value of correlation strength A and its correlation time τ3 play opposite roles on the Tex; （ii） For the case of 0 〈λ〈 1,α and its correlation time τ2 play opposite roles on the Tex in which R〉 1 is the best condition, and there is one-peak structure on the Tex - D plot; （iii） For the case of-1 〈 λ≤ 0, D and its correlation time τ1 play opposite roles on the Tex in which R 〈 1 is the best condition and there is one-peak structure on the Tex - τ2 plot.     

Statistical Properties of Multispecies Competition Ecosystems Subjected to Dichotomous Noises

We investigate statistical properties of multispecies competition ecosystems subjected to both symmetric and asymmetric dichotomous noises. The expression of the stationary probability distribution function (SPDF) is analytically derived by means of mean-field approximation, and verified bystochastic simulations. The results indicate that: (i) A noiseamplitude (a₀), a noise autocorrelation time (τ₀) and a noise symmetry parameter (k) all can affect the SPDF; (ii) There is an optimal τ₀, which makes the mean value of population density be maximal, near which a transition takes place, i.e., the stationary mean value of species density (_st) suddenly falls to a lower constant; (iii) As k decreases, the maximum of< x>_st and the optimal τ₀ increase. The parameter planes of τ₀-a₀² and τ₀-k for the transition are plotted.     

Colored Noises-Induced Regime Shifts in a Vegetation Ecological System

In this paper, we investigate the stationary probability distribution and mean first passage time in a vegetation ecological system, which is driven by cross-correlation between intrinsic and extrinsic colored noises as well as the nonzero cross-correlation in between. The impacts of the self-correlation time τ₁ and τ₂, the cross-correlation time τ₃ and intensity k on the stationary probability distribution and mean first passage time are discussed, respectively. Our main results show that: (#em/em#) the self-correlation time τ₁ can induce regime shifts from the desert state to the sustainable vegetation state, while the self-correlation time τ₂, cross-correlation time τ₃ and intensity k can induce regime shifts from the sustainable vegetation state to the desert state; and (ii) the self-correlation time τ₁ or τ₂ can enhance the stability of the sustainable vegetation biomass, while the cross-correlation time τ₃ or strength k weakens the stability of the sustainable vegetation biomass.     

Stochastic resonance in a bistable system with coloured correlation between additive and multiplicative noise

The phenomenon of stochastic resonance (SR) in a bistable nonlinear system with coupling between additive and multiplicative noises is investigated when the correlation between two noise terms is coloured. It is found that the signal-to-noise ratio (SNR) of the system is affected not only by the coupling strength λ between two noise terms, but also by the noise correlation time τ. The SNR is changed from a single peak, to two peaks with a dip, and then to a monotonically decreasing function with noise strength. The dependence of the SR on the initial conditions is entirely caused by the coupling strength λ between two noise terms.     

Stochastic resonance for a metapopulation system driven by multiplicative and additive colored noises

We investigate the stochastic resonance(SR) phenomenon induced by the periodic signal in a metapopulation system with colored noises. The analytical expression of signal-to-noise is derived in the adiabatic limit. By numerical calculation, the effects of the addictive noise intensity, the multiplicative noise intensity and two noise self-correlation times on SNR are respectively discussed. It shows that:(i) in the case that the addictive noise intensity M takes a small value, a SR phenomenon for the curve of SNR appears; however, when M takes a large value, SNR turns into a monotonic function on the multiplicative noise intensity Q.(ii) The resonance peaks in the plots of the multiplicative noise intensity Q versus its self-correlation time τ1 and the addictive noise intensity M versus its self-correlation time τ2 translate in parallel. Meanwhile, a parallel translation also appears in the plots of τ1 versus Q and τ2 versus M.(iii) The interactive effects between self-correlation times τ1 and τ2 are opposite.     

三价铕荧光络合物与聚乙烯吡咯烷酮复合物研究

为研究稀土荧光络合物与高分子形成的复合物的结构与发光性能间的关系,利用α-噻吩甲酰三氟丙酮（TTA）和三苯基氧化膦（TPPO）与氯化铕（EuCl₃）分别制备了Eu(TTA)₃·2H₂O和Eu(TTA)₃·(TPPO)₂络合物,及其与聚乙烯吡咯烷酮（PVP）的复合物。采用荧光光谱,红外光谱和透射电镜等方法对复合物进行了表征。荧光光谱测定结果表明Eu(TTA)₃·2H₂O与PVP K30结构单元摩尔比为1∶35的PVP/Eu(TTA)₃·2H₂O复合物的612　nm发射峰的荧光强度较Eu(TTA)₃·2H₂O络合物有显著提高。红外光谱研究表明络合物的Eu3+与PVP分子的羰基之间存在着明显的配位作用,并且存在多种配位方式。透射电镜观察结果表明复合物具有微相分离结构,其中的稀土络合物为无定形结构,这进一步表明PVP与络合物分子间存在相互作用。     

Influence of the net gain on characteristic of stochastic resonance in a single-mode laser system

The phenomenon of stochastic resonance (SR) is found in a single-mode laser system driven by the colored pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary parts. When the net gain a0 changes, it is found that, 1) the shape of the curve of the signal-tonoise ratio (SNR) versus the pump noise self-correlation time T exhibits a changing process of multiform SR, from single-peak SR to simultaneous existence of resonances and suppressions; 2) the curve of SNR versus signal frequency Ω experiences a complicated changing process from the monotonous descending to the simultaneous appearances of a maximum and a minimum, and finally to monotonous descending; 3)the curve of SNR versus cross-correlation coefficient between the real and imaginary parts of the quantum noise λq appears an acute single-peak SR. Therefore, the net gain a0 greatly influences the characteristic of SR of laser system.     

Electronic Structure and Magnetic Properties of Cu[C(CN)3]2 and Mn[C(CN)3]2 Based on First Principles

The electronic structure and the magnetic properties of the molecule-based ferromagnets Cu[C(CN)₃]₂ and Mn[C(CN)₃]₂ are studied accordingto first principles within density-functional theory (DFT) and the full potential linearized augmented plane wave (FP-LAPW) method. The total energy, atomic spin magnetic moments, and density of states (DOS) of Cu[C(CN)₃]₂ and Mn[C(CN)₃]₂ are all calculated. The calculations reveal that the compounds have a stable ferromagnetic ground state and half-metallic properties. The total spin magnetic moment is 1.0 μ_B for Cu[C(CN)₃]₂ and 5.0 μ_B for Mn[C(CN)₃]₂ per molecule, the magnetic moment mainly comes from metal atoms, although there is a slight contribution from N and C atoms.     

镁合金阳极氧化膜腐蚀特性的红外显微成像分析

采用显微红外成像技术对镁合金阳极氧化膜表面的腐蚀特性进行了研究。镁合金在7.3 Wt% Na₂SO₄溶液中浸泡后,表面氧化层中的部分MgO逐渐转化为Mg(OH)₂,进而发生溶解和脱落,使得镁合金失去保护作用。当浸泡时间达到2 h时,显微红外成像结果表明阳极氧化膜中Mg(OH)₂的红外吸收信号最强,Mg(OH)₂的含量最多。而4 h后Mg(OH)₂的红外吸收信号开始减弱,Mg(OH)₂开始减少,镁合金不断被腐蚀。氧化膜中另一成分Al₂O₃随浸泡时间的显微红外成像信息与Mg(OH)₂的变化规律相同。采用电化学阻抗谱技术对阳极氧化膜的阻抗进行测试,其阻抗随时间的变化特点基本符合氧化膜腐蚀规律。本研究对于镁合金阳极氧化膜的表征具有很好的指导作用和推广应用价值。     

氮肥施用量和形态对玉米苗期叶绿素含量的影响

氮肥的施用量和形态对植物的影响很大。实验借助于一种新型光谱仪SPAD-502叶绿素仪,研究了不同氮肥水平和氮肥形态对苗期玉米叶片叶绿素含量的影响。结果表明,每公顷施用0,100和200 kgN时,SPAD值在43.3～43.7之间,差异不显著;每公顷施用400 kgN时最后一片展开叶的叶绿素含量显著高于对照和每公顷施用100和200 kgN的处理,估计可能与肥料中其他成分有关,但原因尚需进一步研究。通过不同形态氮肥试验,表明氨态氮处理的叶片叶绿素含量显著高于硝态氮处理,可能的原因是: (1)氨态氮易于吸收,施用初期效果快;(2)氨态氮中微量元素比较高。     

Tunneling Conductance in dx2-y2+idxy Mixed Wave Superconductor Graphene Junctions

Using the extended Blonder-Tinkham-Klapwijk formalism, we investigate the conductance spectra of normal metal/d_x²-y²+id_xy mixed wave superconductor graphene junctions. It is found that the conductance spectra vary strongly with the orientation of the gap and the amplitude ratio (Δ₁/Δ₀) of two components for d_x²-y²+id_xy mixed wave. The zero bias conductance isnearly 2 and the conductance peak vanishes in doped graphene forα=0 and Δ₁/Δ₀=1. The conductance increases with increasing the amplitude ratio of two components for α=π/4 and Δ₁/Δ₀=1. The ZBCP becomesobservable wide with 1F/Δ₀<100 for α=π/4 and Δ₁/Δ₀=1. This property is different from that in normal metal/d_x²-y² wave superconductor graphenejunctions.     

卤代苯甲酸铽与1,10-邻菲哕啉三元配合物的合成及性质

以卤代苯甲酸和1,10-邻菲哕啉为配体,合成了9种Tb(Ⅲ)的三元配合物,以EDTA配位滴定分析和元素分析确定了各配合物的组成。通过红外光谱分析对配合物的结构进行了初步表征,在配合物中羧基氧原子和1,10-邻菲啰啉中的氮原子均参与了配位。采用TG-DTG技术对配合物的热稳定性进行了研究,9种配合物均有较好的热稳定性,它们的热稳定性顺序为:Tb(o-ClBA)₃phen>Tb(o-BrBA)₃phen>Tb(p-ClBA)₃phen>Tb(m-BrBA)₃phen·H₂O>Tb(o-FBA)₃phen>Tb(p-BrBA)₃phen>Tb(p-FBA)₃phen>Tb(m-ClBA)₃phen≈Tb(m-FBA)₃phen·H₂O。在同一条件下测得了各配合物固体粉末的激发和发射光谱,结果表明:相同取代基和相同取代位置的各组配合物的两个较强发射峰(⁵D₄-⁷F₆和⁵D₄-⁷F₅)的荧光强度顺序分别为:Tb(o-FBA)₃phen>Tb(p-FBA)₃phen>Tb(m-FBA)₃phen·H₂O,Tb(m-ClBA)₃phen>Tb(p-ClBA)₃phen>Tb (o-ClBA)₃phen,Tb(p-BrBA)₃phen>Tb(o-BrBA)₃phen>Tb(m-BrBA)₃phen·H₂O和Tb(o-FBA)₃phen>Tb (o-BrBA)₃phen>Tb(o-ClBA)₃phen,Tb(m-ClBA)₃phen>Tb(m-FBA)₃phen·H₂O>Tb(m-BrBA)₃phen·H₂O,Tb(p-BrBA)₃phen>Tb(p-ClBA)₃phen>Tb(p-FBA)₃phen[其中o(m,p)-F(Cl,Br)BA为邻(间,对)氟(氯,溴)苯甲酸根,phen为1,10-邻菲哕啉]。     

2-(4-氟代苯甲酰基)苯甲酸-铕配合物的合成、结构表征及荧光性能的研究

以硝酸铕、2-(4-氟代苯甲酰基)苯甲酸(HL)、1,10-菲咯啉(Phen)和三苯基氧膦(TPPO)合成了EuL₃(H₂O)₆,EuL₃Phen(H₂O)₄和EuL₃(TPPO)(H₂O)₅三种固态配合物。用元素分析、红外光谱、核磁共振氢谱对配合物进行了组分确定和结构表征。IR表明,2-(4-氟代苯甲酰基)苯甲酸与Eu3+形成配合物后,位于1 692 cm-1处羧基的ν_CO峰消失,2 500～3 200 cm-1处羧基的ν_O—H峰也消失,出现了羧酸盐特有的反对称伸缩振动吸收峰(ν_as(CO-₂))和对称伸缩振动吸收峰(ν_s(CO-₂)),且Δν(ν_as(CO-₂)-ν_s(CO-₂))与钠盐的Δν相近,说明羧酸根与Eu3+以对称双齿桥式配位。在1H NMR中,形成配合物后第一配体苯环上的质子峰变为宽峰且移向高场,Phen和TPPO中质子化学位移移向低场。室温下测定了配合物的荧光激发光谱和发射光谱,激发光谱表明配合物EuL₃(H₂O)₆,EuL₃Phen(H₂O)₄和EuL₃(TPPO)(H₂O)₅的最佳激发波长分别为353.0,355.0和357.0 nm;发射光谱均显示Eu3+离子的特征发射光谱,且表明Phen对Eu3+离子的荧光发射有明显增强作用。     

3,4-噻吩二羧酸、1,10-邻菲罗啉与稀土配合物的荧光性质及对硝基苯的检测

3,4-噻吩二羧酸(3,4-H₂tdc),1,10-邻菲罗啉(phen)和稀土硝酸盐经水热法合成三种配合物Ln₂(Htdc)₂(tdc)₂(phen)₂(H₂O)₄(Ln=Eu 1, Gd 2, Tb 3),并用X-射线单晶衍射分析方法测定了配合物1-3晶体结构,配合物1-3为双核分子。每个金属离子周围有2个3,4-tdc,1个3,4-Htdc,1个phen和2个配位水分子,配位数为9。配合物1和3在紫外灯下显强红光和绿光,其荧光发射光谱,在619和545 nm出现最大发射峰,分别对应于Eu(Ⅲ)离子的5D₀→7F₂和Tb(Ⅲ)离子的5D₄→7F₅跃迁。配合物2在425 nm观察到来自基于配体的π*→π最大发射峰。不同溶剂分子对配合物1荧光有不同程度的影响,基于荧光猝灭机理,配合物1具有选择性检测硝基苯污染物的能力。     

Spontaneous U（1） Symmetry Breaking in Coupled Bose System

Adding a U(1) symmetry breaking term V^1/2 a(λ₁a₀+λ*₁a^&#8224;₀)+V^1/2(λ₂b₀+λ^*₂b^&#8224;₀) to Bogoliubov's truncated Hamiltonian H_B for a weakly interacting coupled Bose system, by using the mean-field approximation rather than the c-number approximation, we find that, via a Feshbach resonance at zero temperature, the states of the coupled Bose system are generalized SU(1,1) × SU(1,1) coherent states. The Bose-Einsteincondensation occurs in response to the spontaneous U(1) symmetry breaking.     

分光光度法测定甜叶菊废渣中总黄酮的研究

为建立测定甜叶菊废渣中总黄酮含量的方法,通过比较直接法、AlCl₃法和NaNO₂-Al(NO₃)₃-NaOH法三种显色方法的紫外可见光谱,确定甜叶菊废渣中总黄酮含量测定的最佳方法为NaNO₂-Al(NO₃)₃-NaOH法。分析了测定波长,显色剂用量和反应时间、温度、pH等因素对测定的影响,并从浓度与吸光度的线性关系,稳定性及加标回收率等方面对该法进行了系统研究,结果表明：在波长500 nm处,以芦丁为标准品,在2～24 μg·mL-1范围内呈良好的线性关系,线性相关系数R2=0.999 5。样品加标回收率在96％～104.3％之间,相对标准偏差(RSD)为3.75%。NaNO₂和Al(NO₃)₃的用量都为1.0 mL,反应时间都为6 min,NaOH的用量为15.0 mL,反应时间为15 min。整个显色过程温度为40 ℃,pH为5,进一步优化了NaNO₂-Al(NO₃)₃-NaOH法测定甜叶菊废渣中总黄酮含量的工艺条件。该方法简便快速,重现性好,准确度高,可用于实际检测工作。     

A 9× 9 Matrix Representation of Birman-Wenzl-Murakami Algebra and Berry Phase in Yang-Baxter System

We present a 9×9 S-matrix and E-matrix. A representation of specialized Birman-Wenzl-Murakami algebra is obtained. Starting from the given braid group representation S-matrix, we obtain the trigonometric solution of Yang-Baxter equation. A unitary matrix \breve{R}(x,φ₁,φ₂) is generated via theYang-Baxterization approach. Then we construct a Yang-BaxterHamiltonian through the unitary matrix \breve{R}(x,φ₁,φ₂). Berry phase of this Yang-Baxter system is investigated in detail.     

杂多酸环戊二烯钒衍生物的合成、谱学性质及抗肿瘤活性

合成了杂多酸环戊二烯钒衍生物[Bu₄N]₄[(CpV)PW₁₁O₃₉](1),[Bu₄N]₄H[(CpV)SiW₁₁O₃₉](2)和[Bu₄N]₄[A-β-(η5-CpV)SiW₉V₃O₄₀](3),并通过元素分析、IR、51V和183W NMR谱进行了结构表征。结果表明配合物(1)和(2)为结合型有机金属配合物,(3)为支撑型杂多酸有机金属配合物。体外抗肿瘤活性研究表明化合物(1)对HL-60和B₁₆均具有一定的抑制作用。     

1,8-萘酰亚胺类衍生物的结构特性对其吸收和发射光谱影响的密度泛函研究

利用B3LYP/6-31G(d)方法优化了一系列N取代1,8-萘酰亚胺类物质的结构,利用含时密度泛函TD-B3LYP/6-31+G(d)方法及C-PCM模式,计算了它们在气相及二氯甲烷溶剂中的吸收和发射光谱。利用计算得出的前线轨道电子云分布及其对应的能级对它们的取代基对电子吸收光谱的影响进行了讨论。结果表明：此种方法计算出的二氯甲烷溶剂中的1,8-萘酰亚胺的吸收光谱与实验光谱比较吻和。取代CO基团的CN基团及其成环在吸收光谱和发射光谱中发挥了重要的作用。酰亚胺结构上的改性即CN基团的引入及在萘环上取代基一方面引入了结构上的不对称性,导致了衍生物的偶极矩的增大;同时结构上的改性扩展了萘酰亚胺共轭结构。4位取代NO₂衍生物从基态到第一激发态的Mulliken原子电荷比5位多一些,这意味着5位取代NO₂衍生物提供了较多的电子。对N(Ph)₂ 和N(Me)₂衍生物而言,他们4位取代衍生物提供了更多的电荷。前线轨道电子云表明：OCNCN基团改性扩展和N(Me)₂, N(Ph)₂和NO₂取代基拓展了这类分子的π—π*跃迁范围,从而使得前线轨道能级差降低,它们的吸收和发射光谱也发生了一定程度的红移。对给体取代基而言,它们的4位是电子传输态;对受体取代基NO₂而言,它们的5位是电荷传输态。当NO₂基团与CO基团在同一侧及当N(Me)₂和N(Ph)₂与在CN在同一侧时,此类化合物具有较好的传导特性。从化合物1到4,吸收光谱红移了139 nm。电荷传输越明显,吸收光谱红移的就越多。OCNCO的结构改性及其电荷传输机理为今后的萘酰亚胺类物质的分子设计提供了设计理论依据。     

磷石膏中微量含氟物相的光谱分析

磷石膏中二水硫酸钙(CaSO₄·2H₂O)的含量高达90%以上,是一种重要的再生石膏资源。然而与天然石膏不同,磷石膏中磷、氟、有机物等有害杂质限制了它的实际利用。探明微量杂质氟物相的存在形态、含量及分布规律,对高效脱除磷石膏中杂质氟具有重要的理论价值。采用X射线光电子能谱(X-ray photoelectron spectroscopy, XPS)与电子显微探针(electron microprobe analysis, EMPA)相结合的分析方法,研究了磷石膏中微量含氟物相的主要存在形式和分布规律。结果表明,磷石膏中微量含氟物相主要包括NaF,KF,CaF₂,K₂SiF₆,Na₂SiF₆,Na₃AlF₆,K₃AlF₆,AlF₃·3H₂O,AlF_2.3(OH)_0.7·H₂O,Ca₅(PO₄)₃F,Ca₁₀(PO₄)₆F₂。其中,4.83%的氟以NaF,KF,CaF₂等氟化物形式存在,8.42%的氟以氟磷酸盐Ca₅(PO₄)₃F和Ca₁₀(PO₄)₆F₂形式存在,12.21%的氟以氟铝酸盐Na₃AlF₆和K₃AlF₆形式存在,41.52%的氟以氟硅酸盐K₂SiF₆和Na₂SiF₆形式存在,33.02%的氟以带结晶水的氟化铝AlF₃·3H₂O和AlF_2.3(OH)_0.7·H₂O形式存在。研究表明分析固体样品中微量元素物相时,采用XPS与EMPA相结合的分析方法更具有优势。本研究为磷石膏中微量杂质氟的脱除以及有效回收氟资源提供理论依据。