Hall effect and transverse magnetoresistance in a low-dimensional conductor HfTe5

Temperature dependence of Hall coefficient and transverse magnetoresistance of a low-dimensional conductor HfTe₅ with 1.5 wt. % Zr is reported for the first time up to 12 kOe in magnetic field. Hall coefficient changes sign from positive to negative at the temperature at which the peak of the resistivity has been observed. Temperature dependence of the transverse magnetoresistance has an anomaly. Two-carrier model has been proposed to explain the data qualitatively. These results suggest the change of the electronic structure associated with the charge density wave formation or some other kind of phase transition. Simple chemical bonding consideration shows that the carrier originates from p-like bands.     

Paramagnetic Inversion of the Sign of the Interference Contribution to the Transverse Relaxation of the Imido Protons of the Coordinated Imidazoles in the UniformlyN-Labeled Cytochromec3

In the spectrum of uniformly¹⁵N-labeled cytochromec₃, the relative linewidths of the doublet peaks of the¹⁵N-coupled imido proton of the coordinated imidazole group were reversed on oxidation. This inversion was explained by the interference relaxation process between the electron–proton dipolar and¹⁵N–¹H dipolar interactions. The inversion can be used to assign the imido protons of the coordinated imidazole groups in heme proteins.     

New extremal doubly-even [64, 32, 12] codes

In this paper, we consider a general construction of doubly-even self-dual codes. From three symmetric 2-(31, 10, 3) designs, we construct at least 3228 inequivalent extremal doubly-even [64, 32, 12] codes. These codes are distinguished by their K-matrices.     

Diffraction efficiency increase by corona discharge in photoinduced surface-relief gratings on an azo polymer film

The diffraction efficiency of a surface-relief grating (SRG) was dramatically increased by corona discharge. We fabricated this SRG by applying surface modulation to azo polymer films, using laser interference fringes. The electric charge was deposited upon the SRG by a corona discharge in an oven. The first-order diffraction efficiency measured before and after corona discharge above the glass-transition temperature increased from ~2% to ~40% in a SRG written with a circularly polarized beam. The relief depth of the SRG as measured with an atomic-force microscope also increased, from ~130 nm to ~450 nm. The increase in diffraction efficiency was independent of the writing polarization.     

Contraction-induced cluster formation in cardiac cell culture

The evolution of the spatial arrangement of cells in a primary culture of cardiac tissue derived from newborn rats was studied experimentally over an extended period. It was found that cells attract each other spontaneously to form a clustered structure over the timescale of several days. These clusters exhibit spontaneous rhythmic contraction and have been confirmed to consist of cardiac muscle cells. The addition of a contraction inhibitor (2,3-butanedione-2-monoxime) to the culture medium resulted in the inhibition of both the spontaneous contractions exhibited by the cells as well as the formation of clusters. Furthermore, the formation of clusters is suppressed when high concentrations of collagen are used for coating the substratum to which the cells adhere. From these experimental observations, it was deduced that the cells are mechanically stressed by the tension associated with repeated contractions and that this results in the cells becoming compact and attracting each other, finally resulting in the formation of clusters. This process can be interpreted as modulation of a cellular network by the activity associated with contraction, which could be employed to control cellular networks by modifying the dynamics associated with the contractions in cardiac tissue culture.     

Repeated‐annealing sampling combined with multicanonical algorithm for conformational sampling of bio‐molecules

A novel conformational sampling method (repeated‐annealing sampling method) is proposed to execute an efficient conformational sampling at a reasonable computational cost. In the method, a molecular dynamics simulation is done with repeating an elemental process. An elemental process consists of four subprocesses: high‐temperature run, annealing, room‐temperature run, and fast heating. The sampling is done automatically according to a temperature‐control schedule. The room‐temperature run is treated with the multicanonical algorithm, and the other subprocesses are done with the conventional molecular dynamics algorithm. The method, differing from the generalized ensemble methods recently developed, is not warrantable to give the canonical ensemble because of the nonphysical process in the annealing. However, we observed that the slower the annealing and the longer the high‐temperature run, the closer the sampled conformations to those of the canonical ensemble. A test was performed with tri‐N‐acetyl‐D ‐glucosamine in vacuo, and the results were compared with those from the conventional multicanonical simulation. Not only the reweighted canonical distribution function but also the energy landscape were in good agreement with those from the conventional multicanonical simulation. The potential of mean force also showed a fairly good agreement with that from the conventional multicanonical simulation in the room‐temperature region. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1098–1106, 2001     

Extremal Ternary Self-Dual Codes Constructed from Negacirculant Matrices

In this paper, a construction of ternary self-dual codes based on negacirculant matrices is given. As an application, we construct new extremal ternary self-dual codes of lengths 32, 40, 44, 52 and 56. Our approach regenerates all the known extremal self-dual codes of lengths 36, 48, 52 and 64. New extremal ternary quasi-twisted self-dual codes are also constructed. Supported by an NSERC discovery grant and a RTI grant. Supported by an NSERC discovery grant and a RTI grant. A summer student Chinook Scholarship is greatly appreciated.     

Relationship between fracture toughness and domain size of liquid‐crystalline epoxy resins having polydomain structure

A liquid‐crystalline (LC) epoxy resin was cured at different temperatures and some types of curing systems having different phase structures (isotropic or polydomain, which have a microscopically ordered LC network structure) were obtained. The diameters of each domain in the polydomain system changed from the small to the larger size. The diameters of the LC domains were evaluated using a polarized optical microscope and the polarized microscopy FTIR mapping method. These systems were used to investigate the relationship between the network arrangement and mechanical properties. The fracture toughness of the cured systems was related to the enlargement of the ordered area in the network structures. With the toughness improvement, the meandering cracks were observed at the fracture surfaces. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 156–165, 2009