1,4‐Methano‐11a‐methyl‐4,4a,11,11a‐tetrahydro‐1H‐benzo­[b]­fluoren‐11‐one

The title compound, C₁₉H₁₆O, crystallizes with two mol­ecules of opposite chirality in the asymmetric unit. In both mol­ecules, the naphthalene and cyclo­pentanone moieties are individually planar. The two cyclo­pentane rings adopt envelope conformations, while the cyclo­hexane ring adopts a boat conformation.     

A Tachyonic Scalar Field with Mutually Interacting Components

We investigate the tachyonic cosmological potential V(?) in two different cases of the quasi-exponential expansion of universe and discuss various forms of interaction between the two components—matter and the cosmological constant—of the tachyonic scalar field, which lead to the viable solutions of their respective energy densities. The distinction among the interaction forms is shown to appear in the O _m (x) diagnostic. Further, the role of the high- and low-redshift observations of the Hubble parameter is discussed to determine the proportionality constants and hence the correct form of matter–cosmological constant interaction.     

Vibrational dynamics and heat capacity in poly(L‐lactic acid)

Poly(L ‐lactic acid) (PLLA) (? CH(CH₃) ? COO? )_n is a biodegradable polymer, which exhibits many applications in the biomedical field and where thermoplastics are employed. A comprehensive study of the normal modes and their dispersion in PLLA using Wilson′s GF matrix method as modified by Higgs is being reported. Assignments of calculated normal modes have been made and characteristic features of dispersion curves are discussed. Heat capacity has been calculated via density‐of‐states using Debye relation in the temperature range 10–250 K, which is in fairly good agreement with the experimental data. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 175–182, 2010     

Polyacrylonitrile enzyme ultrafiltration and polyamide enzyme microfiltration membranes prepared by diffusion and convection

Glucose oxidase (GOD) and catalase (CAT) were covalently immobilized onto three types of polyacrylonitrile (PAN 1, PAN 2, and PAN 3) ultrafiltration (UF) membranes with different pore sizes and one type of polyamide (PA) microfiltration (MF) membrane by the bifunctional reagent, glutaraldehyde. The initial membranes were pre-modified to generate active amide groups in the PAN membranes and active amino groups in the PA membranes. The PAN 3 membrane contained the highest amount of active groups, and the membrane PA the lowest. The modified membranes were enzyme-loaded by diffusion and convection (UF). The effect of membrane pore size and immobilization methods on enzymatic activity and bound protein were studied. The most effective immobilized system was prepared by diffusion using a PAN 3 membrane as a carrier (bound protein: 0.055 mg/cm(2), relative activity: 87.6%). This membrane had the highest pore size of all the PAN membranes. Despite the highest pore size of PA membrane, the enzyme PA membranes prepared by diffusion showed the lowest amount of bound protein (0.03 mg/cm(2)) and the lowest relative activity (35.38%). This correlates with the lowest amount of active groups found in these membranes. The relative activity was higher for all the enzyme systems loaded by diffusion. The systems prepared by convection of the enzyme solution contained higher amounts of enzymes (0.035-0.13 mg/cm(2) protein), which led to internal substrate diffusion resistance and a decrease in the GOD relative activity (21.55-68.5%) in these systems. The kinetic parameters (V(max) and K(m)) and the glucose conversion of the immobilized systems prepared by diffusion were also studied. [diagram in text].     

Superconducting tetrahedral quantum bits

We propose a design for a qubit with four superconducting islands in the topology of a symmetric tetrahedron, uniformly frustrated with one-half flux quantum per loop and one-half Cooper pair per island. This structure emulates a noise-resistant spin-1/2 system in a vanishing magnetic field. The flux frustration boosts quantum fluctuations and relieves the constraints on junction fabrication. Variability of manipulation and optimized readout are additional benefits of this design.     

Lattice dynamics of CuBr and CuI by a modified rigid ion model

Phonon dispersion relations of CuBr and CuI have been studied on the basis of a modified rigid ion model in which a non-central force system is used for the short-range interactions. The results of the calculations show a satisfactory agreement with the experimental data.