Nano-colloidal functionalization of textiles based on polysiloxane as a novel photo-catalyst assistant: processing design

Due to the opposite surface charge of TiO(2) and silver nano-particles, at around neutral pH, it is expected that the interaction between these particles and cross-linkable polysiloxane (XPs) resin and thus their final properties would be affected by their processing technique. This paper has focused on the effect of processing design on the interaction, surface orientation and final properties of surface nano-colloidal functionalization. The results disclosed the key role of the applied process on the properties of the treated fabrics which have been well discussed through the modeling of this effect on orientations of nanoparticles on the surface. The developed models are interestingly verified by various characterizations. Applying a premixed TiO(2)/XPs colloid as an after treatment on Ag treated samples caused more enhanced stain photo-degradability and UV protection properties, while the reduction of enhanced hydrophobicity, washing durability, and stain-repellency were observed as compared to applying Ag/XPs premixed colloid on TiO(2). The role of processing on XPs stabilizing efficiency and its co-photo-catalytic function on TiO(2) nanoparticles has been concluded and deeply discussed. The appropriate processing design can be tailored in order to accomplish desirable hydrophilicity/hydrophobicity with a granted bioactivity. The results reveal that ideal bioactivity, stain photo-degradability, self-cleaning, UV protection, anti-staining properties, and washing durability can be achieved by applying a mixture of silver and XPs as an after-treatment on TiO(2) treated fabrics.     

两款原子吸收光谱仪的塞曼背景校正装置

讨论了永久磁场塞曼背景校正原子吸收光谱仪的外光路和磁场的设计工艺,描述了可以同时获得交流磁场和直流磁场塞曼背景校正测定结果的新系统,以及可以克服洛伦兹力对测定产生影响的磁场和石墨炉的供电系统.     

Crystal packing effects within [Mn3O] single-molecule magnets: Controlling intermolecular antiferromagnetic interactions

The reactions of 2-hydroxyphenylethanone oxime (Me-H₂salox) and (2-hydroxy-phenyl)-phenyl-methanone oxime (Ph-H₂salox) with Mn(ClO₄)₂·6H₂O in MeOH afford trinuclear manganese complexes of [Mn₃O(Me-salox)₃(MeOH)₃(ClO₄)]·MeOH (1·MeOH) and [Mn₃O(Ph-salox)₃(MeOH)₃(ClO₄)]·2MeOH (2·2MeOH), respectively. X-ray analysis shows that both complexes contain a manganese triangle core, [Mn^III₃O]⁷⁺. The structural distortion from the twisting of the oxime ligands dominates the ferromagnetic interactions within the three Mn ions in both compounds and results in an S = 6 ground state. The frequency dependence of out-of-phase signals in the alternating current (AC) magnetic susceptibility measurements and the temperature-dependent and sweep-rate-dependent hysteresis loops are indicative of single-molecule magnet behavior. Moreover, both complexes show step-wise magnetization, indicating the occurrence of quantum tunneling of magnetization (QTM). Interestingly, a tail to tail arrangement in the crystal packing of complex 1·MeOH results in strong intermolecular H-bonding interactions and leads to the exchange-bias effect from the antiferromagnetic interaction between the adjacent Mn₃ molecules. In contract, QTM steps of complex 2·2MeOH show an absence of the exchange-bias effect due to a weak intermolecular interaction from a head to tail arrangement.     

Tricomponent azide, tetrazolate, and carboxylate cobridging magnetic systems: ferromagnetic coupling, metamagnetism, and single-chain magnetism

Three novel coordination polymers with azide and a bifunctional zwitterionic ligand bearing carboxylate and tetrazolate as bridging groups, [M(L)(N(3))]·xH(2)O [L=1-(carboxylatomethyl)-4-(5-tetrazolato)pyridinium, M=Cu (1, x=2), Ni (2, x=1), and Co (3, x=1)], have been synthesized and characterized by X-ray crystallography and magnetic measurements. The compounds consist of two-dimensional coordination layers in which uniform anionic chains with the unprecedented tricomponent (μ-azide)(μ-tetrazolate)(μ-carboxylate) bridges are cross-linked by cationic 1-methylenepyridinium spacers. The tricomponent bridges induce ferromagnetic interactions in all the compounds. Furthermore, this isostructural series of ferromagnetic-chain-based compounds has allowed us to observe distinct bulk properties that are dependent upon the natures of the different spin carriers: with the isotropic Cu(II) ion, 1 exhibits a paramagnetic phase of the ferromagnetic chains without long-range magnetic order above 2 K; with the weakly anisotropic Ni(II) ions, 2 displays antiferromagnetic ordering and field-induced metamagnetism without slow dynamic relaxation; and with Co(II), which has strong magnetic anisotropy due to first-order spin-orbital coupling, 3 exhibits magnetic hysteresis and slow magnetization dynamics typical of single-chain magnets.     

On the expressive power of CNF formulas of bounded tree- and clique-width

We study representations of polynomials over a field K from the point of view of their expressive power. Three important examples for the paper are polynomials arising as permanents of bounded tree-width matrices, polynomials given via arithmetic formulas, and families of so called CNF polynomials. The latter arise in a canonical way from families of Boolean formulas in conjunctive normal form. To each such CNF formula there is a canonically attached incidence graph. Of particular interest to us are CNF polynomials arising from formulas with an incidence graph of bounded tree- or clique-width.We show that the class of polynomials arising from families of polynomial size CNF formulas of bounded tree-width is the same as those represented by polynomial size arithmetic formulas, or permanents of bounded tree-width matrices of polynomial size. Then, applying arguments from communication complexity we show that general permanent polynomials cannot be expressed by CNF polynomials of bounded tree-width. We give a similar result in the case where the clique-width of the incidence graph is bounded, but for this we need to rely on the widely believed complexity theoretic assumption #P?FP/poly.     

Low-temperature magnetization relaxation in magnetic molecular solids

The low temperature relaxation of the magnetization in molecular magnetic solids such as Fe₈ is studied using Monte Carlo simulations. A set of rate equations is then developed to understand the simulations, and the results are compared. The simulations show that the magnetization of an initially saturated sample deviates as a square-root in time at short times, as observed experimentally, and this law is derived from the rate equations analytically.     

{Cu3}单分子磁体在磁场中的热纠缠

本文研究单分子磁体Na₉[Cu₃Na₃(H₂O)₉ (α-AsW₉O₃₃)₂]·26H₂O中三角自旋 环在磁场作用下的热纠缠性质, 利用数值计算求出任意两个Cu²⁺离子量子比特之间的配对纠缠度, 分别记为C₁₂, C₂₃和C₁₃. 研究结果表明, 磁场的方向和大小以及温度对配对纠缠度具有重要影响, 而且参数的变化对C₁₂, C₂₃和C₁₃的影响也是各不相同. 给出外加三个不同方向的磁场时, 配对纠缠度C₁₂, C₂₃和C₁₃各自对应的临界温度T_c随磁场强度的变化图, 由此可以得到单分子磁体三角自旋环中存在纠缠态的参数范围. 通过选择适当的磁场方向和大小以及温度等实验参数, 可以有效地调节和提高单分子磁体中的配对纠缠度. 关键词： 配对纠缠 单分子磁体 三角自旋环     

Minimum Permanents on a Face of the Polytope of Doubly Stochastic Matrices II

We determine the minimum permanents and minimizing matrices on the face of z_3+n, for the fully indecomposable (0,1) matrices of order 3+n, which include an identity submatrix of order n .     

High coercivity nanocrystalline YCo5 powders produced by mechanical milling

High coercivity nanostructured YCo₅ powders were successfully prepared by mechanical milling of as-cast alloys and subsequent vacuum annealing. Almost single phase YCo₅ alloys, obtained by arc melting, were processed by high energy mechanical milling using a SPEX 8000 mill. After 4 h of milling, powders become nearly amorphous. DSC scans revealed the existence of an irreversible broad exothermic transition with a maximum at 516 °C associated with the crystallization process. Annealing in high vacuum at 800 °C during 2.5 min led to the formation of YCo₅ nanoparticles with an average particle size of 12 nm. A high intrinsic coercivity of 7.23 kOe together with a σ_r/σ_s ratio of 0.75 were obtained.