On some closed sets in ideal minimal spaces

The purpose of this paper is to introduce ideal minimal spaces and to investigate the relationships between minimal spaces and ideal minimal spaces. We define some closed sets in these spaces to establish their relationships. Basic properties and characterizations related to these sets are given.     

Competing magnetic phases on a kagomé staircase

We present thermodynamic and neutron data on Ni3V2O8, a spin-1 system on a kagomé staircase. The extreme degeneracy of the kagomé antiferromagnet is lifted to produce two incommensurate phases at finite T--one amplitude modulated, the other helical--plus a commensurate canted antiferromagnet for T-->0. The H-T phase diagram is described by a model of competing first and second neighbor interactions with smaller anisotropic terms. Ni3V2O8 thus provides an elegant example of order from subleading interactions in a highly frustrated system.     

Solvent‐Catalyzed Ring–Chain–Ring Tautomerization in Axially Chiral Compounds

The mechanism of ring–chain–ring tautomerization and the prominent effect of the solvent environment have been computationally investigated in an effort to explain the enantiomeric interconversion observed in 2‐oxazolidinone derivatives, heterocyclic analogues of biphenyl atropisomers, which were isolated as single stable enantiomers and have the potential to be used as axially chiral catalysts. This study has shed light on the identity of the intermediate species involved in the ring–chain–ring tautomerization process as well as the catalytic effect of polar protic solvents. These mechanistic details will prove very useful in predicting and understanding ring–chain tautomeric equilibria in similar heterocyclic systems and will further enable experimentalists to devise appropriate experimental conditions in which axially chiral catalysts remain stable as single enantiomers.     

An Online Expectation–Maximization Algorithm for Changepoint Models

Changepoint models are widely used to model the heterogeneity of sequential data. We present a novel sequential Monte Carlo (SMC) online expectation–maximization (EM) algorithm for estimating the static parameters of such models. The SMC online EM algorithm has a cost per time which is linear in the number of particles and could be particularly important when the data is representable as a long sequence of observations, since it drastically reduces the computational requirements for implementation. We present an asymptotic analysis for the stability of the SMC estimates used in the online EM algorithm and demonstrate the performance of this scheme by using both simulated and real data originating from DNA analysis. The supplementary materials for the article are available online.     

Analytical expression to temperature-dependent Kirkwood-Fr?hlich dipole orientation parameter using the Boubaker Polynomials Expansion Scheme (BPES)

An analytical expression is proposed to the Kirkwood-Fr?hlich dipole orientation correlation parameter g. This parameter, which has been considered as a relevant guide to understanding the structuredness of supercritical fluids, had been always determined numerically. The advantage of the used protocol: the BPES, is to yield continuous and integrable expressions which can be easily incorporated in analytical models. The results have been compared to several precedent studies.     

Aromatization of Hantzsch Ester 1,4‐Dihydropyridines with Iodine under Normal Conditions and Ultrasound Irradiation

A variety of Hantzsch ester 1,4‐dihydropyridines are efficiently oxidized to their corresponding pyridine compounds with iodine under normal conditions and ultrasound irradiation. The reactions were carried out in refluxing CH₃CN.     

Kinetic Analysis of Multi Enzyme Systems: A Case Study of the Closed System of Creatine Kinase, Hexokinase and Glucose 6-Phosphate Dehydrogenase

This paper describes a general methodology to handle closed multi enzyme systems using mixture of symbolic (which depends on the Gröbner Basis technique) and numerical computation methods. The applicability of the proposed method has been examined for the closed three-enzyme system of rabbit heart creatine kinase (EC 2.7.3.2), yeast hexokinase (EC 2.7.1.1) and human erythrocyte glucose 6-phosphate dehydrogenase (EC 1.1.1.49) using experimental data.     

A simple theory of 40 K superconductivity in MgB2: first-principles calculations of Tc, its dependence on boron mass and pressure

We have studied the superconducting properties of MgB₂ from first-principles under isotropic, uniaxial, and biaxial compressions. We find that the in-plane boron phonons near the zone-center are very anharmonic and strongly coupled to the planar B σ bands near the Fermi level. This mode is found to be the key to quantitatively explain the observed high T_c, the total isotope effect and the pressure dependence of T_c. We propose that a stringent test on the hole and phonon based theories of the superconductivity in MgB₂ would be a measurement of the biaxial ab-compression dependence of T_c.     

Biological distribution of iodo-allyl gabapentin and iodo-gabapentin

Gabapentin (GBP) is an anticonvulsant and is widely used in the treatment of epilepsy. In this study, GBP and an allyl derivative of GBP were radioiodinated with ¹³¹I using the iodogen method; then their radiopharmaceutical potential in rats and rabbits was investigated. The radiochemical purity of ¹³¹I-GBP and its derivatives was determined by RTLC. The labeling yield was 95±2%. Biological evaluation was performed in normal rats and rabbits. Labeled compounds were intravenously injected into two rabbits via the ear vein after anesthetizing. The dynamic and static scintigrams were obtained using a gamma camera at different time. Then the labeled compounds were administered intravenously into the rats. The distribution was studied by counting the radioactivity in the removed organs. The results of biodistribution in the rats showed the clearance of ¹³¹I-ALGBP was faster than ¹³¹I-GBP. On the other hand, the uptake of ¹³¹I-ALGBP in the brain was higher than ¹³¹I-GBP at 60 minutes.