A 3-D Mn(II) complex containing N-isonicotinyl,N′,N′′-bis(hexamethylenyl) phosphoric triamide ligand: synthesis,structural characterization,and thermal studies

A new phosphoryl-containing ligand, N-isonicotinyl, N′,N′′-bis(hexamethylenyl) phosphoric triamide (1), was synthesized and characterized using IR, ¹H, ¹³C, and ³¹P NMR and UV–vis spectroscopy. Reaction of 1 with MnCl₂·4H₂O led to the formation of Mn(II) complex with the formula {Mn[4-NC₅H₄C(O)NHP(O)(NC₆H₁₂)₂]₂Cl₂}_n (2). Crystal structures of 1 and 2 were determined by X-ray crystallography, which reveals that 2 is centrosymmetric with two phosphoryl oxygens, chloride and nitrogen in trans positions. Coordination of bridged bidentate 1 through oxygen of the phosphoryl and nitrogen of the pyridine afforded a 3-D network extended by coordinative bonds. Compound 2 and its nano-sized particles prepared by sonochemical method were characterized by IR spectroscopy, X-ray powder diffraction, and thermal analysis and exhibited paramagnetic behavior at room temperature. Crystalline mixture of Mn₂P₂O₇ and Mn₂P₄O₁₂ was identified as a thermolysis product of 2.     

Impact of initial lattice structures on networks generated by traces of random walks

We show that the platform stage of network evolution plays a principal role in the topology of resulting networks generated by short-cuts stimulated by the movements of a random walker, the mechanism of which tends to produce power-law degree distributions. To examine the numerical results, we have developed a statistical method which relates the power-law exponent γ to random properties of the subgraph developed in the platform stage. As a result, we find that an important exponent in the network evolution is α, which characterizes the size of the subgraph in the form V∼t^α, where V and t denote the number of vertices in the subgraph and the time variable, respectively. 2D lattices can impose specific limitations on the walker’s diffusion, which keeps the value of α within a moderate range and provides typical properties of complex networks. 1D and 3D cases correspond to different ends of the spectrum for α, with 2D cases in between. Especially for 2D square lattices, a discontinuous change of the network structure is observed, which varies according to whether γ is greater or less than 2. For 1D cases, we show that emergence of nearly complete subgraphs is guaranteed by α<1/2, although the transient power-law is permitted at low increase rates of edges. Additionally, the model exhibits a spontaneous emergence of highly clustered structures regardless of its initial structure.     

A Distributed and Collaborative Beamforming algorithm for a self-organizing Wireless Sensor Network

In this paper the scenario where sensors of a Wireless Sensor Network (WSN) are able to process and transmit monitored data to a far collector is considered. The far collector may be a Base Station (BS) that gathers data from a certain number of deployed WSNs, in applications such as earthquake, tsunami, or pollution monitoring. In this paper, the possible use of Distributed and Collaborative BeaMForming (DC-BMF) technique is analyzed, with the goal of enhancing the capability of a single sensor to communicate its data to the far collector. This technique considers nodes as elements of a phased array, where the phases of the signals at each antenna node are linearly combined in order to adjust the directional gain of the whole array. In particular, a novel self-localization technique for WSNs performing DC-BMF is studied, a closed form solution for beamforming gain degradation is derived and the evaluation of the power consumption of the proposed DC-BMF algorithm is provided.     

Transient fluctuation of the prosperity of firms in a network economy

The transient fluctuation of the prosperity of firms in a network economy is investigated with an abstract stochastic model. The model describes the profit which firms make when they sell materials to a firm which produces a product and the fixed cost expense to the firms to produce those materials and product. The formulas for this model are parallel to those for population dynamics. The swinging changes in the fluctuation in the transient state from the initial growth to the final steady state are the consequence of a topology-dependent time trial competition between the profitable interactions and expense. The firm in a sparse random network economy is more likely to go bankrupt than expected from the value of the limit of the fluctuation in the steady state, and there is a risk of failing to reach by far the less fluctuating steady state.     

On the L<Subscript>∞</Subscript>-norm of extreme points for crossing supermodular directed network LPs

We discuss extensions of Jain’s framework for network design [8] that go beyond undirected graphs. The main problem is approximating a minimum cost set of directed edges that covers a crossing supermodular function. We show that iterated rounding gives a factor 3 approximation, where factor 4 was previously known and factor 2 was conjectured. Our bound is tight for the simplest interpretation of iterated rounding. We also show that (the simplest version of) iterated rounding has unbounded approximation ratio when the problem is extended to mixed graphs.      

The multi-layered network design problem

We address the problem of designing a network built on several layers. This problem occurs in practical applications but has not been studied extensively from the point of view of global optimisation, since the problem of designing a single-layered network is complex. An example of an application is the design of a virtual network (Internet Protocol) built on a sparse optical transport network.     

人工神经网络法同时测定混合氨基酸

应用三层ANN-BP网络解析苯丙氨酸(Phe)、色氨酸(Try)和酪氨酸(Tyr)的紫外可见吸收光谱,同时测定三种氨基酸组分.通过对网络结构和参数的优化,提高了预报的准确度,最后对水解大豆样品进行测定,得到了满意的结果.     

Synthetic Strategies for the Selective Functionalization of Carbon Nanodots Allow Optically Communicating Suprastructures

The surface of Carbon Nanodots (CNDs) stands as a rich chemical platform, able to regulate the interactions between particles and external species. Performing selective functionalization of these nanoscale entities is of practical importance, however, it still represents a considerable challenge. In this work, we exploited the organic chemistry toolbox to install target functionalities on the CND surface, while monitoring the chemical changes on the material's outer shell through nuclear magnetic resonance spectroscopy. Following this, we investigated the use of click chemistry to covalently connect CNDs of different nature en-route towards covalent suprastructures with unprecedent molecular control. The different photophysical properties of the connected particles allowed their optical communication in the excited state. This work paves the way for the development of selective and addressable CND building blocks which can act as modular nanoscale synthons that mirror the long-established reactivity of molecular organic synthesis.     

Structural, spectral and thermal properties of a polymeric nickel(II) complex containing two-dimensional network

The structure of the complex [Ni(hmt)(NCS)₂(H₂O)₂]_n, assembled by hexamethylenetetramine (hmt) and octahedral Ni(II), is reported. Crystal data: Fw 351.07, a=9.885(10) Å, b=12.06(1) Å, c=12.505(8) Å, β=114.41(4)°, V=1357(1) ų, Z=4, space group=C2/c, T=173 K, λ(Mo−K)=0.71070 Å, ρ_calc=1.718 gcm⁻¹, μ=17.44 cm⁻¹, R=0.099, Rw=0.145. The tetrahedral assembling template effect of the hmt molecule is completed by two coordination bonds and two hydrogen interactions. The UV–vis absorption spectrum of this complex [Ni(hmt)(NCS)₂(H₂O)₂]_n with a two-dimensional network is determined in the range of 5000–35000 cm⁻¹ at room temperature. The observed spectrum is discussed and explained perfectly by the scaling radial theory proposed by us. The two-dimensional structure has no apparent effects on the d–d transitions of the central Ni(II) ion. The IR spectrum and the GT curve of the complex were also measured and clearly reflect its structural properties.     

GeO_2-PbO-ZnO红外玻璃的Raman光谱和结构

用Ｒａｍａｎ光谱研究了ＧｅＯ２ ＰｂＯ ＺｎＯ玻璃结构,结果表明,这种三元系统红外玻璃主要以［ＺｎＯ４］单元和含两个非桥氧的［ＧｅＯ４］四面体单元共同构成三维网络。网络中含两个非桥氧的［ＧｅＯ４］四面体数量随ＰｂＯ含量增加而增加,而低含量的ＺｎＯ则能提高网络中［ＧｅＯ４］四面体单元的聚合度。