Syntheses,Crystal Structures and Thermal Stabilities of Two New Mixed Ligated Coordination Polymers with Rigid Dicarboxylate and Flexile N-donor Ligands

Two new coordination polymers,[Co（BIPA）（bpp）]（1） and [Zn（BIPA）（bpp）（H2O）]（2）（H2BIPA = 5-bromoisophthalic acid,bpp = 1,3-di（4-pyridyl）propane） have been synthesized via hydrothermal reactions.The two compounds were characterized by elemental analysis,IR spectra,TG analysis and single-crystal X-ray determination.Compound 1 crystallizes in triclinic,space group P1 with a = 9.0316（13）,b = 10.1179（14）,c = 11.8884（17） ,α = 68.022（2）,β = 84.749（2）,γ = 77.791（2）°,V = 984.5（2） 3,Z = 2,C21H17BrN2O4Co,Mr = 500.21,Dc = 1.687 g.cm-3,μ = 2.932 mm-1,S = 0.981,F（000） = 502,R = 0.0440 and wR = 0.1357 for 3773 observed reflections with I 2σ（I）.Compound 2 crystallizes in the monoclinic system,space group P21/c with a = 7.8466（10）,b = 27.483（4）,c = 9.6583（13） ,β = 96.663（3）°,V = 2068.8（5） 3,Z = 4,C21H19BrN2O5Zn,Mr = 524.66,Dc = 1.685 g.cm-3,μ = 3.155 mm-1,S = 0.969,F（000） = 1056,R = 0.0441 and wR = 0.0517 for 4058 observed reflections with I 2σ（I）.The two compounds are constructed from the BIPA2-and bpp ligands but they exhibit different kinds of one-dimensional chain structures.In 1,the chains are composed of the Co（Ⅱ） ions and BIPA2-ligands,and the chains are further extended into a 2D framework structure by π...π interactions of the benzene rings from the BIPA2-ligands between the adjacent chains.In 2,the chains are made up of Zn（Ⅱ） ions and BIPA2-ligands through another fashion,and the chains are further linked via hydrogen bonding interactions to yield a two-dimensional supramolecular layer structure.Furthermore,the bpp ligand features two kinds of different coordination modes in the two compounds.

Public Transit Connectivity Measures and Analysis of Weak Segments

Bus and any other public transit connectivity issues facilitate an understanding of the importance of transit planning in enhancing existing or new transit services. Improving transit connectivity is one of the most vital tasks in transit-operations planning. A poor connection can cause some passengers to stop using the transit service. Service-design criteria always contain postulates to improve routing and scheduling coordination （intra- and inter-agency transfer centers/points and synchronized/timed transfers）. Ostensibly the lack of well-defined connectivity measures precludes the weighing and quantifying of the result of any coordination effort. This work provides an initial methodological framework and concepts for （1） quantifying transit connectivity measures and （2） directions and tools for detecting weak segments in inter-route and inter-modal chains （paths） for possible revisions/changes.

Effect of the coordinated reset stimulations on controlling absence seizure

Based on a macroscopic mean-field model associating with the thalamus and cerebral cortex, we investigate how the newly proposed coordinated reset stimulation(CRS) strategy controls the absence seizures as some key parameters are changed.Different from the previous stimulation processes, CRS represents the intermittent pulse current administered to different structures including cortex, specific relay nuclei(SRN) and thalamus reticular nucleus(TRN) at different time by using three different micro-electrodes. In particular, we first simulate a typical absence epilepsy activity under the combined effect of the coupling strength between inhibitory interneurons(IIN)-excitatory pyramidal neurons(EPN) and EPN-TRN pathway. And then we explore the control mechanism of different parameters of 3:2 ON-OFF CRS on spike and slow-wave discharges(SWDs)region. Through analyzing the corresponding two-dimensional bifurcation diagrams, we find CRS is effective on controlling absence seizures in proper ranges of stimulation parameters. Especially, the combination of frequency and positive input duration can inhibit the pathological area more effectively. The obtained results might be helpful to study the pathophysiology mechanism of epilepsy, although the CRS's feasibility still needs further exploration in clinical experiments.

Functional Transformation of Rural Homesteads:A Field Survey of Poyang County,Jiangxi Province,China

The rural homestead is a major part of the rural land system,which is an important carrier of various rural issues such as rural decline,rural hollowing and others.Great changes have occurred in China’s rural areas,while the rural homestead has also undergone transformation.Based on summarizing the multi-functional classification of homesteads from previous research,this study divided and defined the population bearing function,assets,and residential function of homesteads from the perspective of functional improvement according to the results of a survey questionnaire.Using Poyang County as the case study,this paper analyzed the functional transformation of rural homesteads through the model of coordinated transformation degree.The results demonstrated the following trends.(1)From 2000 to 2017,the transformation degrees of rural homestead functions in Poyang County have obviously improved overall.(2)The high value areas of the transformation degrees were mainly distributed in the northern hilly region and around Poyang Lake,while most of the low value areas were distributed in the plain areas near the county town.(3)In the regions with better location conditions and resource endowments,the basic conditions and trend of non-agriculturalization of the population,capital and other factors are more significant.According to the differentiation of rural homestead transformations which occurred in different regions,the government could put forward targeted development suggestions for the future.

Synthesis and spectroscopic studies of Zn4B6O13 and Eu/Tb single-doped Zn4B6O13 phosphors

In this study, Zn4B6O13, Eu-and Tb-doped Zn4B6O13 phosphors were prepared by conventional solid state reaction method and the samples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM） and photoluminescence spectroscopy（PL）. The doped rare-earth ions had little influence on the crystal structure of Zn4B6O13, but obviously affected the morphology of Zn4B6O13 particles. The PL results indicated that the 5% Eu-doped sample and 1% Tb-doped sample had the highest intensity in their respective different concentrations doped samples. The CIE chromaticity coordinates indicated that Zn4B6O13, Zn4B6O13：Eu and Zn4B6O13：Tb showed the three basic colors of blue, red and green, respectively. Evidently, the white light could appear only at appropriate intensity of blue, red and green components.

Improved luminescent properties of SrZn_2(PO_4)_2:Sm^(3+) doped with Li^+, Na^+ and K^+ ions

SrZn2(PO4)2:Sm3+ phosphor was synthesized by a high temperature solid-state reaction in atmosphere. SrZn2(PO4)2:Sm3+ phosphor is efficiently excited by ultraviolet(UV) and blue light, and the emission peaks are assigned to the transitions of 4G5/2-6H5/2(563 nm), 4G5/2-6H7/2(597 nm and 605 nm) and 4G5/2-6H9/2(644 nm and 653 nm). The emission intensities of SrZn2(PO4)2:Sm3+ are influenced by Sm3+ concentration, and the concentration quenching effect of SrZn2(PO4)2:Sm3+ is also observed. When doping A+(A=Li, Na and K) ions, the emission intensity of SrZn2(PO4)2:Sm3+ can be obviously enhanced. The Commission Internationale de l'Eclairage(CIE) color coordinates of SrZn2(PO4)2:Sm3+ locate in the orange-red region. The results indicate that the phosphor has a potential application in white light emitting diodes(LEDs).