Viscometric assay for determining lysozyme activity

A method was developed for determining the activity of lysozyme using two pipettes as a viscometer. The proposed viscometric assay uses carboxymethylchitin as a substrate and measures the enzyme activity at 22°C. The method requires only simple manipulations with the use of readily available laboratory equipment and the determination of enzyme activity is rapid.     

Structure and properties of Bi2Sr2CaCu2Ox/Bi2Sr2CuOx superlattices prepared by RF magnetron sputtering

We have prepared Bi₂Sr₂CaCu₂O_x/Bi₂Sr₂CuO_x (2212/2201) superlattices with various stacking periodicity by multitarget RF magnetron sputtering. Their crystal structure and electrical properties were investigated. The superlattice was found to be successfully constructed from the data of XRD patterns, AES, etc. The critical temperature increased almost linearly with increasing thickness of the 2212 phase up to a thickness of 6 unit cells. On the other hand, it did not decrease as the thickness of the 2201 layers was increased. The unit cell/unit cell superlattice showed T_{c zero} of 30 K.     

Density of surface states of ordered adlayers

A method for calculating Green functions has been obtained by extending the continued fraction expansion method. It is applicable to a quasi-tridiagonal hamiltonian. The surface density of states of ordered adlayers has been studied by this method within the tight-binding approximation. Local densities of states of the outermost and the following few atomic planes are calculated for the (2 × 1) and (1 × 2) overlayer on a simple cubic (110) surface. It is found that the effect of long range order of the overlayer and of adsorption site is very important for the electronic structure of the adlayer. The nonbonding state, a new kind of surface state characteristic of the ordered adlayer, is obtained. It is shown that the energy of the nonbonding state degenerates at the orbital energy of an adatom when the direct interaction between adatoms is negligible, so that the states provide a strong peak in the adsorbate band for certain overlayer structures.     

Magnetic specific heat of the honeycomb lattice of spin one-half with anisotropic Heisenberg exchange by a new method

The magnetic specific heat of the honeycomb lattice of $\text{S =}\text{1}\text{2}$ Heisenberg spin with anisotropic exchange is calculated by using the new approximation method reported in a previous paper. In the spin system with the anisotropy parameter |γ|<1 (Ising-Heisenberg system), the specific heat shows a similar divergence as that of the pure Ising spin system, namely a logarithmic divergence at the critical temperature. The same approximation is also applied to the spin system with |γ|>1 (Heisenberg XY system), showing a divergence of the same kind.     

Random collision model for random genetic drift and stochastic difference equation

Summary At first we introduce a simple stochastic difference equation, to simulate random sampling drift in population genetics, which is naturally obtained from a random collision model. Next, we introduce a random collision model to simulate overdominance model in population genetics. We assume in a time interval °t, a random collision of four particles, which represents overdominant selection, takes place at a certain probability, where a particle corresponds to a gene. We assume that mutation takes place by some rate and assume that every new mutation is different from extant alleles. We estimate mean heterozygosity by our simulation method and compare it with the result obtained by using a stochastic difference equation for overdominance model. The Institute of Statistical Mathematics     

Microwave spectrum,molecular structure,and nuclear quadrupole coupling constants of 3-bromopropene

The microwave spectra of the two ⁷⁹Br and ⁸¹Br isotopic species of 3-bromopropene were measured in the frequency region 14–23 GHz. The R and Q branches for a- and b-type rotational transitions of one conformer, skew, have been assigned and the rotational constants of the ground state have been determined to be A = 19 247.56 MHz, B = 1975.339 MHz, and C = 1914.761 MHz for ⁷⁹Br species, and A = 19 234.26 MHz, B = 1961.417 MHz, and C = 1901.563 MHz for ⁸¹Br species, respectively. By the analysis of the second-order perturbation treatment of the quadrupole interaction, it is found that the χ_ab element of the χ tensor primarily contributes to the anomalous hyperfine splittings. The matrix elements of products of direction cosines in terms of the symmetric top wavefunctions have been derived. The nuclear quadrupole coupling constants have been determined χ_aa = 384.2 MHz, χ_bb = ?71.9 MHz, χ_cc = ?276.3 MHz, and |χ_ab| = 358.7 MHz for ⁷⁹Br species and χ_aa = 283.2 MHz, χ_bb = ?55.6 MHz, χ_cc = ?227.6 MHz, and |χ_ab| = 296.0 MHz for ⁸¹Br species.     

Pyrolysis of amines: Infrared spectrum of allylimine

Infrared absorption spectrum of allylimine in the gas phase was measured for the first time. The spectrum consisted of two rotational isomers, cis and trans, around the CC bond. The relative population of the trans form was 70–80%, and the rest was for the cis form at room temperature. This intermediate molecule was produced by the thermal decomposition of diallylamine and by the isomerization of propargylamine. The vibrational assignments were made with the help of an ab initio MO calculation. The half-life in the absorption cell was about 20 min.