Evolution of aeronautical communications for personal and multimedia services

The demand to make air travel more pleasant, secure, and productive for passengers is one of the winning factors for both airlines and the aircraft manufacturing industry for which aeronautical communications is one of the enablers. This article describes current trends in the area of aeronautical passenger communication toward personal and wireless in-cabin communications and multimedia data networks. Technological challenges are summarized as well as market potentials and regulatory issues.     

Diaquabis(4,4-bipyridine)copper(II) di(o-sulfobenzimidate) dichloromethane solvate, a two-dimensional Cu4(4,4-C5H4NC5H4N)4 rhombic grid clathrating guest dichloromethane

In the crystal structure of bis(4,4^′-bipyridine)diaquacopper(II) di(o-sulfobenzimidate) dichloromethane solvate, the host polycationic [Cu(4,4^′-C₅H₄NC₅H₄N)₂(H₂O)₂]_∞ rhombic grids stack over each other 8.16 Å apart along the c-axis of the orthorhombic Pbcn unit cell. The Cu₄(4,4^′-bpy)₄ rhombus clathrating a disordered dichloromethane molecule has a copper atom at the corner and the spacer heterocycle with pyridyl rings twisted by 21.8(2)°, as its side. The anions occupy the space between the layers; the grids interact with each other indirectly through water–anion hydrogen bonds [OO=2.766(4); ]. The structure sets a remarkable example of potentials born by the polyfunctional o-sulfobenzimidate moiety for construction of unusual architectures.     

Synthesis and Characterization of Magnetite/Carbon Nanocomposite Thin Films for Electrochemical Applications

Stable colloidal suspension of magnetite/starch nanocomposite was prepared by a facile and aqueous-based chemical precipitation method.Magnetite/carbon nanocomposite thin films were subsequently formed upon carbonization of the starch component by heat treatment under controlled conditions.The initial content of native sago starch as the carbon source was found to affect the microstructure and electrochemical properties of the resulted magnetite/carbon nanocomposite thin films.A specific capacitance of 124 F/g was achieved for the magnetite/carbon nanocomposite thin films as compared to that of 82 F/g for pure magnetite thin films in Na 2 SO 4 aqueous electrolyte.     

Performance of intersegment handover protocols in an integratedspace/terrestrial-UMTS environment

The universal mobile telecommunications system (UMTS) will deliver a convergent network incorporating cellular, cordless, wireless local loop, and satellite technologies. A signaling protocol for intersegment handover (ISHO) in an integrated space/terrestrial-UMTS environment is presented. After discussing a number of possible ISHO scenarios, backward mobile-assisted handover (HO) incorporating signaling diversity is chosen as the most appropriate ISHO scheme. Based on the generic radio-access network (GRAN) concept and by using a satellite-UMTS network architecture and functional model, the derivation of an ISHO protocol is presented. The performance of this protocol is analyzed and evaluated in terms of the service interruption time, execution signaling time, and the end-to-end signaling time. Simulation results show that, in agreement with the GRAN concept, the service interruption time is independent of the signaling protocol and depends only on the satellite round-trip delay and the radio interface characteristics. The interarrival rate of the ISHO requests affect the performance of the protocol only when the value of the mean service time is increased. However, even in such a situation, the performance of the protocol is still considered acceptable     

循环流化床锅炉在我厂的应用

本文介绍循环流化床锅炉在河南开封化肥厂的应用情况，包括选型，设备概况，工程建设及投运等，并解释了几个问题，说明这种类型的锅炉对以煤为原料制气的氮肥厂是一个综合利用的好项目，既节能又利于三废治理。     

A facile approach for controlled synthesis of hydrophilic starch‐based nanoparticles from native sago starch

A facile approach for the preparation of hydrophilic starch‐based spherical nanoparticles from native sago (Metroxylon sagu) starch using the drop‐wise solvent exchange method was reported. Starch‐maleate monoester (SM) was initially synthesized from native sago starch and maleic anhydride in an aqueous medium, and SM nanoparticles was subsequently precipitated in absolute ethanol under controlled conditions. The present study was focused mainly on modulating of the solvent and non‐solvent systems to prepare SM nanoparticles of different morphologies. The pH of the solvent system and the nature of surfactants being added into the solvent system could influence the morphology of regenerated SM nanoparticles. SM nanoparticles of discrete and spherical shape were regenerated from a basic SM sample solution, or an acidic sample solution in the presence of an appropriate surfactant. SM nanoparticles with mean diameter of about 250 nm was obtained by precipitation in absolute ethanol in the presence of Brij 35 as the surfactant.     

Mixing and Crystallization Kinetics in Gas‐liquid Reactive Crystallization

A study of gas‐liquid reactive crystallization for CO₂‐BaCl₂‐H₂O system was performed in a continuous flow crystallizer. The influences of mixing on the crystallization kinetics of barium carbonate crystals were investigated. The mixing parameters are stirrer speed, feed concentration, gas‐flow rate, pH of solution, addition rate of NaOH solution, and mean residence time. Under pH‐stat operation, the crystallization mechanism can be assessed by the addition rate of NaOH solution, which acts as an indicator for the absorption rate of carbon dioxide. Assuming a size‐independent agglomeration mechanism, the nucleation rate, growth rate and agglomeration kernel can be obtained, simultaneously, at steady state, by the method of moments. Evidence shows that feed concentration, feed rate, gas‐flow rate, and stirrer speed have a significant influence on the nucleation rates and mean particle sizes. This shows the effect of micromixing. The crystallization mechanism tends to be reaction limited when the feed concentration of barium chloride solution is higher than 5 mM, while at lower stirrer speeds and feed concentrations, the mechanism tends to be both mixing and reaction controlled. The growth rate depends on the mean supersaturation value and the pH of the solution and the mass‐transfer resistance cannot be completely eliminated in this work. For a monodispersal collision model, in the viscous sub‐range of turbulence, the agglomeration kernel can be expressed as β ∝ d^{3 –1/4}, showing a low efficiency of collision. The result is also demonstrated by the agglomeration kernel expression. Comparison with a liquid‐liquid‐mixing reactive crystallization system is also discussed.     

Hydrothermal synthesis and crystal structure of the first layered iron molybdate KH3Fe2Mo2O10

The layered iron molybdate compound, KH₃Fe^II₂Mo^VI₂O₁₀, has been hydrothermally synthesized and structurally characterized for the first time. The compound crystallizes in monoclinic space group C2/m with a=9.6448(7), b=6.5946(4), , β=115.950(1)°, , Z=2, and R1=0.0313, wR2=0.0817. The structure consists of FeO₆ octahedra and MoO₄ tetrahedra. Each FeO₆ octahedron shares edges with its adjacent FeO₆ octahedra and leads to a chain consisting of edge-sharing FeO₆ octahedron. The parallel chains are linked through MoO₄ tetrahedra. Each MoO₄ tetrahedron shares corners with two adjacent Fe octahedra through the vertical oxygen atoms of each FeO₆, and two adjacent Fe octahedra through an oxygen atom bridging the two adjacent Fe octahedra of its neighboring chain, respectively. A ∞-like 2D layers and pseudo-six-side tunnels are formed and the potassium cations are located in the pseudo-channels.     

Syntheses and Characterization of Two New M(II)-5,5′-dimethyl-2,2′-bipyridine (M = Cd and Pb) Coordination Polymers and Study of Their Thermal and Electrochemical Properties

Two new cadmium(II) and lead(II)-thiocyanato coordination polymers with 5,5′-dimethyl-2,2′-bipyridine (5,5′-dm-2,2′-bpy) as chelating ligands were synthesized and characterized by elemental analysis, IR and ¹H NMR spectroscopy and by X-ray crystallography. Thermal and electrochemical properties were also studied as well. These complexes have formed formula [Cd(5,5′-dm-2,2′-bpy)(NCS)₂]_n (1) and [Pb(5,5′-dm-2,2′-bpy)(CH₃COO)(NCS)]_n (2). The coordination numbers of Cd^II in 1 and Pb^II in 2 are six (CdN₄S₂) and seven (PbN₃O₃S₂), respectively. In 2, “stereo-chemically active” electron lone pairs and the coordination spheres were hemidirected. Bridging properties of thiocyanato anions in 1 and 2 created one- and two-dimensional coordination polymers, respectively. The supramolecular features in these complexes were guided and controlled by weak directional intermolecular interactions.