Study of ultrasonic absorption in the intermediate state of pure superconducting tin

Ultrasonic absorption studies in the intermediate state of superconducting tin have revealed sharp resonance peaks. Measurements have been made under wide variations of ultrasonic pulse frequencies. The possibility of correlating this study with a model proposed by Claiborne and Einspruch for hard superconducting alloys has been explored.     

Exchange interaction in trinuclear transition-metal complexes

Heterotrinuclear transition-metal complexes are of interest for the study of long-range magnetic interactions and as model compounds for the investigation of biological electron transport chains. The systems under study here contain paramagnetic Fe¹¹¹-containing terminal units and a bridging unit with M¹¹=Zn, Cu, Ni, Co, Fe, Mn. The spectroscopic methods applied include Mössbauer, — EPR- and magnetic susceptibility investigations. The spin-Hamiltonian analysis of the measured results yields information about the intramolecular super-exchange interactions among the various magnetic transmition-metal sites. In view of the 7Å separation between the two terminal Fe¹¹¹ sites, the Fe¹¹¹...Fe¹¹¹ exchange coupling of the order ?10cm^?1 is large.     

Two step-down tests for equality of covariance matrices

The classical problem of testing the equality of the covariance matrices from k ? 2 p-dimensional normal populations is reexamined. The likelihood ratio (LR) statistic, also called Bartlett’s statistic, can be decomposed in two ways, corresponding to two distinct component-wise decompositions of the null hypothesis in terms of the covariance matrices or precision matrices, respectively. The factors of the LR statistic that appear in these two decompositions can be interpreted as conditional and unconditional LR statistics for the component-wise null hypotheses, and their mutual independence under the null hypothesis allows the determination of the overall significance level.     

A new theory for including short range order in the cluster Bethe lattice method: Application to the Hubbard model

A new theory for incorporating short range order (SRO) in the cluster Bethe lattice method (CBLM) for disordered binary alloys is proposed. It is applied to determine the condition for the appearance of moments in the disordered phase of a narrow-band metal for general values of concentration and SRO parameter. The final result (i) yields all the known limiting conditions exactly and (ii) displays in a transparant form the SRO dependence, indicating the merit of the present approach.     

Highly Birefringent Photonic Crystal Fibers BUsing Asymmetric Core Design

We demonstrate a highly birefringent photonic crystal fiber by utilizing the asymmetric core design. Based on spectral measurements of the polarization mode interfering, we estimate that the fiber has a beat length of about 0.33 mm at 1545 nm.     

An EOQ Model for Deteriorating Items with Time Varying Demand and Costs

A generalized EOQ model for deteriorating items is considered here in which the demand rate, deterioration rate, holding cost and ordering cost are all assumed to be continuous functions of time. Shortages are also allowed and are completely backlogged. The planning horizon is finite and the replenishment periods are assumed to be constant. The optimal replenishment policy and the decision rule which minimizes the total system cost are derived. A numerical example is given to illustrate the developed model. Sensitivity analysis is also presented for the given model.     

Structure of Globularidin: An Unusual Iridoid Glucoside from Globularia alypumL.

A novel iridoid glucoside, named globularidin, lacking the typical double bond between C(3) and C(4), has been isolated from the whole plant of Globularia alypum by the combination of open column- and high-performance liquid chromatography. The structure of this compound was established by chemical transformation and spectral data.     

Alkali-metal trifluoromonosulphatomanganates (III) A2[MnF3(SO4)] (A = NH4, Li,Na or K)

Pink-brown crystalline alkali-metal trifluoromonosulphatomanganates(III), A₂[MnF₃(SO₄)] (A = NH₄, Li, Na or K), have been synthesised in high yields by reacting KMnO₄ or MnO(OH) with 40% HF and A₂SO₄ or by the reaction of MnO(OH) with 40% HF and A₂S₂O₈ (A = NH₄ or K). The chemicallly estimated oxidation state of manganese occurs between 2.9 and 3.1, and the room temperature magnetic moments lie in the range 4.0–4.2 BM. (NH₄)₂[MnF₃(SO₄)] on being pyrolysed at 340°C yields MnSO₄.