Charge density effects in salt‐free polyelectrolyte solution rheology

Solution rheology of 2‐vinyl pyridine and N‐methyl‐2‐vinyl pyridinium chloride random copolymers in ethylene glycol was studied over wide ranges of concentration and effective charge. The fraction of quaternized monomers α and the fraction of monomers bearing an effective charge f of these copolymers were measured using counterion titration and dielectric spectroscopy, respectively. Ethylene glycol is a good solvent for neutral poly(2‐vinyl pyridine), with very few ionic impurities. The viscosity η and relaxation time τ of dilute and semidilute unentangled solutions exhibit the scaling with concentration and effective charge expected by the Dobrynin model. Reduced viscosity data are independent of concentration in dilute solution, giving an intrinsic viscosity that depends on effective charge, and the experimental data obey the Fuoss law in the semidilute unentangled regime. Scaling concentration with the overlap concentration (c/c*) reduces these data to common curves, and c* ～ f ^?12/7 as predicted by the Dobrynin model, where f is the fraction of monomers bearing an effective charge. While the overlap concentration depends strongly on effective charge until counterion condensation occurs, the entanglement concentration c_e is surprisingly insensitive to effective charge, indicating that entanglement effects are not understood using the Dobrynin model. The terminal modulus G = η/τ depends only on the number density of chains G = ckT/N for c* < c < c_e, and G ～ c^3/2 for c > c_e independent of the effective charge. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2001–2013, 2006     

Freedom from the interpolation property for tense calculi associated with Ershov spaces

We study into the question whether calculi associated with Ershov topological spaces possess Craig’s interpolation property. Supported by RFBR grant No. 06-01-00358, by INTAS grant No. 04-77-7080, and by the Council for Grants (under RF President) and State Aid of Fundamental Science Schools, project NSh-4787.2006.1. __________ Translated from Algebra i Logika, Vol. 46, No. 6, pp. 745–762, November–December, 2007.     

Thickness dependence of the magnetic anisotropy of Fe layers separated by Al

Magnetic multilayers of ⁵⁷Fe with nominal thickness, T _nom, between 0.4 and 1.0 nm separated by 3.0 nm Al spacer layers were prepared by alternate deposition of the constituents in high vacuum. The samples were investigated at 4.2 K in external magnetic field. A fraction of Fe atoms corresponding to about 0.3 nm equivalent Fe-thickness was found to mix into the Al spacer. The extremely strong magnetic anisotropy observed for T _nom < 0.8 nm is attributed to Fe layers of approximately two atomic planes thick. The anisotropy decreases considerably after the building up of the third Fe atomic layer starts at T _nom = 0.8 nm, but full saturation was not achieved even for T _nom = 1 nm and 3 T magnetic field applied perpendicularly to the sample plane.     

Formation and magnetic properties of Co–Fe-based bulk metallic glasses with supercooled liquid region

A new Co–Fe-based ferromagnetic bulk metallic glass (BMG) was synthesized by copper mould casting method. The thermal stability and crystallization processes were investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The soft magnetic behavior was studied by DC magnetic measurements. The high glass formation ability was interpreted in terms of the effective suppression of nucleation and growth of the intermetallic compounds which appear in the multicomponent system during solidification. The high thermal stability indicates that the new Co–Fe-based BMG could be used as high-temperature magnetic material. The low coercivity which was as low as 8 A/m for the as-cast sample was found in the Co–Fe-based metallic glass cylinder with a diameter of 1.5 mm.     

2-Dimension from the Topological Viewpoint

In this paper we study the 2-dimension of a finite poset from the topological point of view. We use homotopy theory of finite topological spaces and the concept of a beat point to improve the classical results on 2-dimension, giving a more complete answer to the problem of all possible 2-dimensions of an n-point poset.      

A reply to “a comment on generalized electromagnetism and Dirac algebra”

Issues raised by W. A. Rodrigues, Jr. are discussed.1. This is not a new result; see,e.g., Rohrlich.⁽³⁾ 2. A typographical error in Eq. (77) is corrected here: The productj A in the right-hand parentheses was erroneously transcribed in Ref. (2) as A.3. I define electromagnetic fieldF = A to be that generated by electric charges and the magnetoelectric fieldG = M to be that generated by magnetic monopoles:F F +₅ G. 4. Rodrigues, on the other hand, takes the position that the importance of the Lagrangian formulation should be downgraded if not discarded altogether: ... it is redundant to look for Lagrangians.⁽¹⁾ 5. In fact, he reformulates it using the language of differential forms.6. It is interesting to observe that this bilinear form has the additional virtue of being appropriate for dealing with the monopolecharge parity question, which was pointed out long ago.⁽¹⁴⁾ 7. In fact, even mathematics looks to Nature for its authority.⁽¹⁶⁾ There is evidence that Rodrigues does not understand this concept.⁽¹⁷⁾     

Magnetic resonance in amorphous metals based on Fe in the millimeter radiowave range

The research technique of amorphous magnetics is described. The paper gives the experimental data obtained by a multifunctional low-temperature radiospectrometer Buran in the mm radiowave range and presents their analysis.     

配位聚合物{[MnL][FeⅡFeⅢ(ox)3·1.5H2O]}∞的合成及其磁学性质

合成和表征了一种新的Schiff碱配合物MnL(ClO4)*3H2O(1)(其中L为n(水杨醛)∶n(二乙撑三胺)=1∶1缩合而成的Schiff碱).1与FeSO4*7H2O和K3[Fe(ox)3]*3H2O(ox=oxalate)进一步反应,生成了双金属层状配位聚合物{[MnL][FeⅡFeⅢ(ox)3]*1.5H2O}∞(2).IR和Mssbauer谱测定结果表明,2具有二维层状结构,其阴离子层由[FeⅡFeⅢ(ox)3]-单元构成.变温磁化率(5K～100K)测试结果表明,2中的自旋载体之间存在反铁磁交换作用.5K时的磁滞现象表明2在低温时可能存在铁磁有序,这可能是亚铁磁或自旋倾斜造成的.     

A class of interaction-round-a-face models and its equivalence with an ice-type model

A new model (called the Temperley-Lieb interactions model) is introduced, in two-dimensional lattice statistics, on a square lattice . The Temperley-Lieb equivalence of this model to the six-vertex, self-dual Potts, critical hard-hexagons and critical nonintersecting string models is established. A graphical equivalence of this model to the six-vertex model generalizes this equivalence to noncritical cases of the above models. The order parameters of a specialization of this model are studied.