风险项目的投资期权分析

本文讨论了风险投资家向企业主融资时的投资期权,求出了投资期权的表达式,并对其中的一些参数进行了分析.     

The trees for which maximum multiplicity implies the simplicity of other eigenvalues

Among those real symmetric matrices whose graph is a given tree T, the maximum multiplicity is known to be the path cover number of T. An explicit characterization is given for those trees for which whenever the maximum multiplicity is attained, all other multiplicities are 1.     

Axisymmetric impingement of a hot jet on a flat plate: equilibrium flow analysis of high-temperature air

The flow structure of an underexpanded supersonic jet with high reservoir temperature impinging on a flat plate has been numerically investigated using a Total Variation Diminishing (TVD) scheme. When the temperature of the flow field is high enough to cause chemical reaction, the specific heat ratio,, is no longer equal to 1.4, nor constant. This explains the difference found in the literature between the flow properties of the calorically perfect gas and that of the chemically reacting flow. Under the equilibrium flow assumption the effect of high temperature gas on the impinging jet has been taken into account in the present paper by using specific heat ratio and speed of sound given by correlation polynomials of thermodynamic variables. The limiting case of cold jet calculation in the present numerical results agreed well with the existing experimental data. For the equilibrium jet with high reservoir temperature,T _o=1000K, qualitative support of the present result has been provided by means of the approximation theory.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society.     

Real‐time electro‐diffusion method to discriminate carbon nanomaterials

We report both the experimental and theoretical insights of differential electro‐diffusion behavior of carbon nanomaterials (e.g. single wall, multiwall carbon nanotubes, and graphene). We thus discriminate one from the other in a soft gel system. The differential mobility of such material depends on their intrinsic properties, both extend and rate of migration bearing the discriminatory signature. The mobility analysis is made by a real time monitoring of the respective bands.     

Reduced Graphene Oxide Supported Cobalt Bipyridyl Complex for Sensitive Detection of Methyl Parathion in Fruits and Vegetables

Herein, we are described a green route to prepare reduced graphene oxide supported cobalt inorganic complex nanocomposite (GRGO/[Co(bpy)₃]) (bpy=2,2′‐bipyridine) through facile and wet chemical approach. The formation of the nanocomposite was confirmed through suitable physical and chemical characterization techniques. The GRGO/[Co(bpy)₃] nanocomposite was coated on the pretreated glassy carbon electrode (GCE). The GCE/GRGO/[Co(bpy)₃] modified electrode has excellent electrocatalytic ability towards methyl parathion reduction, while the overpotential drops drastically to –0.18 V (vs. Ag/AgCl). Moreover, the effect of concentration, scan rate and electrolyte pH were detail studied. Besides, the linear response range was 0.05‐1700 μM and the detection limit was 0.0029 μM (S/N=3) and the sensitivity was 1.8197 μA μM⁻¹ cm⁻². Moreover, the fabricated electrode has high level of selectivity, which delivers satisfactory repeatability, reproducibility and stability. The sensing method was successfully demonstrated in real samples such as, tomato and apple samples.     

Wedge Operations and Doubling Operations of Real Toric Manifolds

This paper deals with two things.First,the cohomology of canonical extensions of real topological toric manifolds is computed when coefficient ring G is a commutative ring in which 2 is unit in G.Second,the author focuses on a specific canonical extensions called doublings and presents their various properties.They include existence of infinitely many real topological toric manifolds admitting complex structures,and a way to construct infinitely many real toric manifolds which have an odd torsion in their cohomology groups.Moreover,some questions about real topological toric manifolds related to Halperin's toral rank conjecture are presented.     

Real analytic families of harmonic functions in a planar domain with a small hole

We consider a Dirichlet problem in a planar domain with a hole of diameter proportional to a real parameter ?   and we denote by _u?$u_{?}$ the corresponding solution. The behavior of _u?$u_{?}$ for ?   small and positive can be described in terms of real analytic functions of two variables evaluated at (?,1/log??)$(?,1/\log ??)$. We show that under suitable assumptions on the geometry and on the boundary data one can get rid of the logarithmic behavior displayed by _u?$u_{?}$ for ?   small and describe _u?$u_{?}$ by real analytic functions of ?. Then it is natural to ask what happens when ? is negative. The case of boundary data depending on ? is also considered. The aim is to study real analytic families of harmonic functions which are not necessarily solutions of a particular boundary value problem.     

Fluorogenic ratiometric dipodal optode containing imine-amide linkages: Exploiting subtle thorium (IV) ion sensing

The (13E,19E)-N1′,N3′-bis[4-(diethylamino)-2-hydroxybenzylidene]malonohydrazide (L) has been developed for the detection of Th⁴⁺ ions using dual channel signalling system. The UV–vis absorbance and fluorescence spectroscopic data revealed the formation of L–Th⁴⁺ complex in 1:1 equilibrium. The density functional theory (DFT) also confirms the optimum binding cavity for the recognition of metal ion. The binding constant computed from different mathematical models for an assembly of L–Th⁴⁺. The detection limit of L for Th⁴⁺ recognition is to a concentration down to 0.1 μM (0.023 μg g⁻¹). The present sensing system is also successfully applied for the detection of Th⁴⁺ ion present in soil near nuclear atomic plants.     

Picomole‐level Formaldehyde Determination in Gaseous and Beer Samples Using Flow Injection Chemiluminescence Analysis

Based on the linear enhancement of formaldehyde (FA) within 7.0 ～ 1000 pmol l^?1 on luminol—bovine serum albumin (BSA) chemiluminescence (CL) system, FA determination in air and beer samples using CL with flow injection (FI) was proposed. The detection limit was 2.5 pmol l^?1 (3σ) and the relative standard deviations were less than 4.5% (n = 7). At a flow rate of 2.0 mL min^?1, a whole analysis from sampling to washing only needed 32 s, offering a sample throughput of 112 h^?1. This proposed method was successfully utilized to determine FA vapor pressure in liquid (121.8 ± 3.8 Pa), FA content in real air sample (8.93 ± 0.03 mg m^?3), and FA levels in beer (199.5 ± 5.6 ～ 225.2 ± 3.5 mg l^?1), giving determination recoveries from 90.7% to 109.3%. The mechanism of BSA—FA interaction was also investigated, showing FA binding to BSA was a spontaneous process mainly through hydrogen bonding and van der Waals force by FI‐CL, with binding constant K of 1.89 × 10⁶ l mol^?1 and the number of binding sites n of 0.86. Molecular docking analysis further revealed FA could enter into the pocket at subdomain IIA of BSA, with K of 1.71 × 10⁵ l mol^?1 and ΔG of ‐29.68 kJ mol^?1.     

Archimedean operator-theoretic Positivstellensätze

We prove a general archimedean positivstellensatz for hermitian operator-valued polynomials and show that it implies the multivariate Fejer-Riesz theorem of Dritschel-Rovnyak and positivstellensätze of Ambrozie-Vasilescu and Scherer-Hol. We also obtain several generalizations of these and related results. The proof of the main result depends on an extension of the abstract archimedean positivstellensatz for ?-algebras that is interesting in its own right.