SBIRS-HIGH对导弹上升段位置测量精度及中末段位置预报精度的分析

根据目前的技术水平分析了高空天基红外系统(SBIRS-HIGH)的技术参数;理论上计算了SBIRS-HIGH对导弹上升段的位置测量精度以及中末段任意时刻飞行位置的预报精度;研究了SBIRS-HIGH对中段和末端导弹拦截系统的导引能力。     

The adsorption of endothelin 1 to phospholipids is governed by electrostatic interactions: A monolayer and fluorescence study

In order to elucidate the influence on the lipidic environment on the recognition process of its membrane associated receptor, the interactions of the vasoconstrictor peptide endothelin 1 with various phospholipids have been investigated using different lipidic model membranes: monolayers at constant surface pressure, vesicles and micelles. A monolayer study of ET1 adsorbed onto the water surface has shown that the C-terminus of the peptide points towards the aqueous phase. Penetration measurements into lipidic monolayers indicate that ET1 adsorbs to phospholipids with an orientation similar to that of the air–water interface and fluorescence measurements are in agreement with such an orientation of the peptide. This adsorption is selective for neutral phospholipids and indicates that the nature of the phospholipid headgroups is of major importance for the approach of the membrane associated receptor.     

Precise Conductance Measurements on Dilute Aqueous Solutions of Sodium and Potassium Hydrogenphosphate and Dihydrogenphosphate

Precise conductance measurements are reported on dilute aqueous solutions of the sodium and potassium salts of orthophosphoric acid at 25 ^∘C. Conductance measurements on solutions of electrolytes such as these phosphate salts that exist in solution as complicated mixtures of ions have previously proved difficult to interpret. To overcome this, a mathematical method has been developed to calculate the concentrations of all the species in the aqueous system M₃PO₄/M₂HPO₄/M₂HPO₄/H₃PO₄ (M = Na or K) over a continuous range of stoichiometries. The Lee–Wheaton conductance equation has been used to interpret the conductance of these multicomponent solutions in terms of the limiting ionic conductances and concentrations of all the ions in the solution. The limiting molar conductances of the ions H₂PO₄ ⁻ and HPO₄ ²⁻ and the ion-pair formation constants of these ions with sodium and potassium ions were determine This work has enabled the accurate determination of solution parameters for the important hydrogenphosphate ions in water and provides an excellent example of the use of an advanced conductance theory in the analysis of the conductance of multicomponent electrolyte systems.     

Synthesis and dispersion of Ni(OH)2 platelet-like nanoparticles in water

Synthesis of nanometric platelet-like Ni(OH)2 particles is described. The role of several experimental parameters on the particle size is investigated. A colloidal dispersion of particles is produced by adsorbing ionizable organic ligands (trisodium citrate) on the particle surface. The stability of this colloidal dispersion and the particle charge density are determined for different citrate ions concentrations.     

Probing the glycosidic linkage: UV and IR ion-dip spectroscopy of a lactoside

The beta(1-->4) glycosidic linkage found in lactose is a prevalent structural motif in many carbohydrates and glycoconjugates. Using UV and IR ion-dip spectroscopies to probe benzyl lactoside isolated in the gas phase, we find that the disaccharide unit adopts only a single, rigid structure. Its fully resolved infrared ion-dip spectrum is in excellent agreement with that of the global minimum structure computed ab initio. This has glycosidic torsion angles of phi(H) (H1-C1-O-C4') approximately 180 degrees and psi(H) (C1-O-C4'-H4') approximately 0 degrees which correspond to a rotation of approximately 150 degrees about the glycosidic bond compared to the accepted solution-phase conformation. We discuss the biological implications of this discovery and the generality of the strategies employed in making it.     

Spherical models with a Gates-Penrose-type phase transition

Gates and Penrose have given criteria under which classical gases with weak long-range interactions fail to be described by the van der Waals equation with Maxwell's rule. Unfortunately, examples of equations of state for such systems have not yet been produced. This paper examines the Gates-Penrose class of interactions-i.e.,U (r)=q(r)+(r), in the limit0, where the Fourier transform (p) has a minimum at a nonzero value ofp-for the spherical model on a one-dimensional lattice. Free energy and magnetization isotherms are computed; it is seen that there is a phase transition, but that the zero-field spontaneous magnetization is always zero (a parahelicoidal phase). However, the pair-correlation function may exhibit either long-range order or the appearance of oscillation.     

The structure of Li3.4Si0.7S0.3O4 by powder neutron diffraction

The structure of Li_4?2xSi_1?xS_xO₄ (x ≈ 0.32) has been determined from neutron powder diffraction studies at room temperature, 350, and 700°C. This compound, which is a member of the series of ionic-conducting solid solutions formed between Li₄SiO₄ and Li₂SO₄, is isostructural with Li₃PO₄. The space group is Pmnb, with a = 6.1701(1), b = 10.6550(2), c = 5.0175(1)Å at room temperature. The distribution of lithium ions suggests the occurrence of a defect cluster in which the inclusion of an interstitial lithium ion causes displacements of the adjacent lithium ions of the normal Li₃PO₄ structure. There appears to be little variation of the structure with temperature.     

Collective behavior of Franck-Condon excited states and energy transfer in DNA double helices

Absorption of UV radiation by DNA bases is known to induce carcinogenic mutations. The lesion distribution depends on the sequence around the hotspots, suggesting cooperativity between bases. Here we show that such cooperativity may intervene at the very first step of a cascade of events by formation of Franck-Condon states delocalized over several bases and subsequent energy transfer faster than 100 fs. Our study focuses on the double helix poly(dA).poly(dT), whose fluorescence, induced by femtosecond pulses at 267 nm, is probed by the upconversion technique and time-correlated single photon counting, over a large time domain (100 fs to 100 ns). The time-resolved fluorescence decays and fluorescence anisotropy decays are discussed in relation with the steady-state absorption and fluorescence spectra in the frame of exciton theory.     

Kinetics and equilibrium of multicomponent adsorption on chiraly templated surfaces

In this contribution we propose a simple model of adsorption of a binary (racemic) mixture on a chiraly templated surface. As an example, the adsorption of a liquid mixture of enantiomers on a chiral stationary phase (CSP) is considered. In particular, we study the effect of the lateral interactions in the adsorbed phase on the kinetic and equilibrium isotherms of the enantiomers. Additionally, we investigate the influence of the composition of the surface on the performance of the CSP in the presence of the lateral interactions. To that end, the adsorption of the mixture is modeled by using Monte Carlo simulations as well as by applying an analytical approach involving rate equations coupled with the Mean Field Approximation (MFA). The predictions of the theory are found to be in good agreement with the results of the simulations.     

Morse theory on timelike and causal curves

It is shown that the set of timelike curves in a globally hyperbolic space-time manifold can be given the structure of a Hubert manifold under a suitable definition of timelike. The causal curves are the topological closure of this manifold. The Lorentzian energy (corresponding to Milnor's energy, except that the Lorentzian inner product is used) is shown to be a Morse function for the space of causal curves. A fixed end point index theorem is obtained in which a lower bound for the index of the Hessian of the Lorentzian energy is given in terms of the sum of the orders of the conjugate points between the end points.