Interpolymer complexes of poly(N-vinylpyrrolidone) with copolyimide-grafted side chains of poly(methacrylic acid)

The process of formation and structural organization of interpolymer complexes formed by macromolecules of poly(N-vinylpyrrolidone) and poly(methacrylic acid) chains grafted onto polyimide in solution is investigated via the method of polarized luminescence. A luminescent label of anthracene structure is covalently bound to both polymers. Relaxation times characterizing intramolecular mobility of each of the components in their interpolymer complex are measured in relation to the composition of the system.     

Relaxation properties and complex formation of copolymers of 2-deoxy-2-methacrylamido-D-glucose and unsaturated acids

With the use of polarized luminescence, relaxation times characterizing the intramolecular mobility of luminescent labeled copolymers of 2-deoxy-2-methacrylamido-D-glucose and unsaturated acids in solutions are determined in both nonionized and ionized states. Elements of the secondary structure typical for poly(methacrylic acid) are formed in copolymers with a high content of methacrylic acid (≥50 mol %) in their nonionized state. This structure is destroyed during ionization. Equilibrium stability constants for complexes of the copolymers with cationic surfactants are determined. Quantitative characteristics of the effects of the surfactant and copolymer structures and the ionic strength of solution on complex formation are estimated.     

Explosive decomposition of pentaerythritol tetranitrate pellets containing nickel nanoparticles with various radii

The kinetics of the explosive decomposition of pressed pentaerythritol tetranitrate pellets containing nickel nanoparticles with various radii has been investigated experimentally, with the explosion initiated by a neodymium laser pulse (wavelength, 1064 nm; pulse duration at half-height, 14 ns), and probability curves for this process have been recorded. The experimental values of critical initiation energy density corresponding to 50% explosion probability are 0.9, 0.7, and 1.4 J/cm² at a nickel particle radius of 67, 78, and 138 nm, respectively. The initial time interval in which the intensity of light emission accompanying the explosive decomposition increases begins during the action of the pulse and is described by a Gaussian function with an effective constant of k = (1.4 ± 0.1) × 10⁸ s^–1, which is independent of the nanoparticle radius. Experimental data of this study can be interpreted within the micro-hotspot model of thermal explosion.     

产品电磁兼容性标准及整改措施

本文主要论述电磁兼容(EMC)对产品质量的重要性以及国家军用标准对产品电磁兼容的相关要求,通过分析部分产品电磁兼容检测超标原因,探讨如何提高产品电磁兼容性的有效手段.     

HRTEM study of new series of oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6)

Arrangements of Cu and anion groups (CO3 and NO3) in the charge-reservoir (CR) blocks of a series of new oxycarbonitrate superconductors (Cu,C,N)Sr2Ca(n - 1)Cu(n)O(y) (n = 1-6) were examined by means of electron diffraction and high-resolution transmission electron microscopy (HRTEM). The first three members with n = 1-3 [Tc = 33 K (n = 1), 91 K (n = 2), 90 K (n = 3)] show the 4a0-type superstructures with periodic arrangements, [-Cu-X-X-X-Cu-X-X-X-Cu-] (X = CO3, NO3), in the CR blocks. The third member (n = 3) partly contains the 2a0-type of superstructure with [-Cu-X-Cu-X-Cu] in the CR blocks. The fourth member with n = 4 (Tc = 113 K) contains only the 2a0-type of superstructure. The higher members, with n = 5 (Tc = 65 K) and n = 6 (Tc = 52 K), show no evidence of ordering in the CR blocks, suggesting random arrangements of Cu and anion groups.     

Green Determination of Total Iron in Water by Digital Image Colorimetry

A green iOS digital image colorimeter was fabricated for the determination of total iron in natural water. A mobile application operating on an iOS device was designed using Euclidean distance theory to perform iron determination. The application records the components of the color by storing red, green, and blue values as well as calculating the hue, saturation, brightness, and gray values using standard color theory. The component values obtained from the images of orange solutions of iron(II) complex with 1,10-phenanthroline were collected in a database and used for evaluation of the total iron concentration in water samples. Under the optimal conditions for solid-phase extraction used for sample preconcentration, the enrichment factor was 8.18. The iron concentration was determined by this device for concentrations from 0.01 to 1.0?ppm. The iOS digital image colorimeter achieved a limit of quantitation of 0.1?ppm. The accuracy and precision of the iOS digital image colorimeter were validated using a certified reference material, riverine water. The instrumentation was used for the analysis of natural water samples.     

Pyrazolate-bridged binuclear zinc complexes Zn<Subscript>2</Subscript>(μ-dmpz)<Subscript>2</Subscript>(Hdmpz)<Subscript>2</Subscript>(OOCR)<Subscript>2</Subscript> (R = Me,Ph; Hdmpz = 3,5-dimethylpyrazole)

Triethylamine reacts with aqueous zinc acetate and the product of its thermolysis in the presence of benzoic acid to yield the complexes [Zn₇(μ₄-O)(μ-OOCMe)₁₀][η-OC(Me)OHNEt₃]₂ (1) and [Zn₂(μOOCPh)₄][η-OC(Me)OHNEt₃]₂ (2), respectively. The reactions of 1 and 2 with 3,5-dimethylpyrazole at room temperature in benzene yield pyrazolate-bridged binuclear complexes Zn₂(μdmpz)₂(Hdmpz)₂(OOCR)₂ (R = Me (3), Ph (4)). The structures of complexes 1–4 have been determined by X-ray crystallography.     

Water-soluble polymer derivatives of cholesterol

New cholesterol-containing water-soluble polymers based on N-methacryloyl aminoglucose and N-vinylpyrrolidone are synthesized by free-radical copolymerization and polymer-analogous transformations. Binary and ternary copolymers of various composition containing N-allylamine and N,N,N-trimethylaminoethyl methacrylate methyl sulfate units and cholesterol residues are prepared. Luminescently labeled copolymers of the same composition are obtained. Effects of the nature of polymers and the amount of cholesterol in them on the intramolecular mobility of macromolecules in solution are studied with polarized luminescence. When 2–4 mol % of cholesterol residues are incorporated into the copolymer, the intramolecular mobility of macromolecules decreases, thus indicating formation of intramolecular compact structures via interaction of nonpolar cholesterol groups. In copolymers containing charged groups, these structures are looser than those in neutral copolymers. It is shown that macromolecules of cholesterol-containing polymers of various types can interact with each other. 1 This work was supported by the Russian Foundation for Basic Research (project no. 08-03-00324) and the Council for Grants of the President of the Russian Federation for Support of Leading Institutes of Higher Education (NSh-4391.2008.3).     

Characterization of the structure and dynamics of an aqueous Hg solution by an ab initio molecular dynamics study

Quantum mechanical charge field (QMCF) MD simulation has been performed to investigate the structure and dynamics of Hg²⁺ hydrate. The first-shell hexacoordinated [Hg(H₂O)₆]²⁺ complex with an average Hg²⁺-O distance of 2.40 Å is dominantly found, which corresponds to the neutron diffraction and extended X-ray absorption fine structure (EXAFS) experiments. Other species, in particular the 7-fold coordinated complexes, can be formed transiently, according to the water exchange processes with an associative interchange (I_a) mechanism. The second hydration shell exhibits a Hg²⁺-O distance of 4.6 Å with a coordination number of ~ 14. The mean residence times (MRTs) of first- and second-shell waters clearly indicate a strong “structure-forming” ability of Hg²⁺ in aqueous solution.     

激光熔敷NiCrSiB合金组织与物相研究

报道了对ＮｉＣｒＳｉＢ激光熔敷合金中共晶组织的研究和观察，将共晶中的第二相标定为Ｎｉ３１Ｓｉ１２。γ′（Ｎｉ３Ｓｉ）相与γ（Ｎｉ，Ｃｒ）相共存于枝晶中，共晶包围着枝晶形成合金的基体，其上弥散分布着硬质强化相ＣｒＢ，Ｎｉ３Ｂ和Ｍ２３（ＣＢ）６。研究方法包括ＳＥＭ（扫描电子显微镜），电子探针，ＸＲＤ（Ｘ射线衍射），ＥＤＡＸ（能谱分析）和波谱分析等