Sound generation and flow interaction of vortices with an airfoil and a flat plate in transonic flow

The mechanisms of sound generation and the kind of interaction of vortices with airfoils in an airflow are investigated. Experiments have been performed in stationary flow with vortices of a Kármán vortex street and in a shock tube flow with a starting vortex of a lifting airfoil. Depending on the dimensions of vortices and airfoils, their distance, and the flow Mach numbers, different kinds and amplitudes of upstream propagating steep sound waves occur.     

Fluorinated NAD as an affinity surfactant

Nicatinamide adenine dinucleotide (NAD) with an attached perfluoropolyether tail acts as an affinity surfactant in the extraction of the enzyme horse liver alcohol dehydrogenase (HLADH) from an aqueous medium into a fluorous solvent.     

The thermal decomposition of transition-metal complexes containing heterocyclic ligands: 2.Benzoxazole complexes

Enthalpies of the overall decomposition reactions

and of the intermediate reactions involving stepwise loss of ligand, L, where M is Mn, Co, Ni, Cu, or Cd, X is Cl or Br, and L is benzoxazole, 2-methylbenzoxazole, or 2,5-dimethylbenzoxazole have been measured by use of a differential scanning calorimeter. Specific heats of CoCl₂(2-methylbenzoxazole)₂, and CoBr₂(2-methylbenzoxazole)₂ are reported together with enthalpies of sublimation of CoCl₂(2-methylbenzoxazole)₂, CoBr₂(2-methyl-benzoxazole)₂, CoCl₂(2,5-dimethylbenzoxazole)₂ and CoBr₂(2,5-dimethylbenzoxazole)₂. Enthalpies of decomposition of benzoxazole complexes are found to be greater than those of the corresponding pyridine complexes, but less than those of the analogous benzothiazole complexes. However, the mean bond dissociation energies of the cobalt—nitrogen and cobalt—oxygen bonds in these complexes are all in the region 33±2 kcal mol^?.     

The thermal decomposition of transition-metal complexes containing heterocyclic ligands: 3. Substituted pyridine complexes of cobalt

Enthalpies of the overall decomposition reactions CoX₂L₂(c) → CoX₂(c)+2L(g) and of the intermediate stepwise loss of ligand, L, where X is Cl or Br, and L is 3-chloropyridine, 3-bromopyridine, 2-chloropyridine, 2-bromopyridine, or 2-methoxypyridine have been measured by use of a differential scanning calorimeter. Enthalpies of sublimation of CoCl₂(3-chloropyridine)₂, CoBr₂(3-chloropyridine)₂, CoCl₂(3-bromopyridine)₂, CoCl₂(2-chloropyridine)₂, CoCl₂(2-bromopyridine)₂, CoBr₂(2-bromopyridine)₂, CoCl₂(2-methylpyridine)₂ and CoBr₂(2-methylpyridine)₂ have been determined. Values of the cobalt-nitrogen bond dissociation energies have been calculated. Specific heats of a number of the complexes are reported.     

Biosynthetic studies of marine lipids—3 : Experimental demonstration of the course of side chain extension in marine sterols

The Pacific sponge Aplysina fistularis was fed cholesterol-[4-¹⁴C],(24R)-methyl-25-dehydrocholesterol-[26-¹⁴C] (epicodisterol[26-¹⁴C]), (24S)-methyl-25-dehydrocholesterol-[26-¹⁴C] (codisterol-[26-¹⁴C]), and 24-methylenecholesterol-[28-¹⁴C]. Only epicodisterol, which has the same stereochemistry at C-24 as (24R,25S)-24,26-dimethylcholesterol (aplysterol), was converted with high efficiency into (24R)-24,27-dimethyl-25-dehydrocholesterol (25-dehydroaplysterol). Further side chain extension [to E-(24R)-24,26,27-trimethyl-25-dehydrocholesterol (verongulasterol)] could also be demonstrated.     

The primal-dual algorithm as a constraint-set-manipulation device

A general primal—dual algorithm for linearly constrained optimization problems is formulated in which the dual variables are updated by a dual algorithmic operator. Convergence is proved under the assumption that the dual algorithmic operator implies asymptotic feasibility of the primal iterates with respect to the linear constraints. A general result relating the minimal values of an infinite sequence of constrained problems to the minimal value of a limiting problem (constrained by the limit of the sequence of constraints sets) is established and invoked. The applicability of the general theory is demonstrated by analyzing a specific dual algorithmic operator. This leads to the MART algorithm for constrained entropy maximization used in image reconstruction from projections.     

Chemical modification of cellulose nanocrystals and their application in thermoplastic starch (TPS) and poly(3‐hydroxybutyrate) (P3HB) nanocomposites

The effect of sulfated (original), carboxylated (oxidized), and Jeffamines M2005‐grafted cellulose nanocrystals (CNCs) on the barrier and mechanical properties of thermoplastic starch (TPS) and poly(3‐hydroxybutyrate) (P(3HB)) matrices was investigated. CNCs were first oxidized via a catalytic reaction using NaClO as an oxidant and then grafted with an amine‐terminated ethylene oxide (EO)/propylene oxide (PO) copolymer (Jeffamine) by an amine‐acid coupling reaction. A degree of oxidation (DO) of 0.108 (mol/mol of anhydroglucose) was attempted for the carboxylated CNCs, whereas a degree of substitution (DS) of 0.04 (mol/mol of anhydroglucose) was determined for the M2005‐grafted CNCs. These values indicated satisfactory reactive process, with yields of 68% and 47.3% for the carboxylation and peptide coupling reactions, respectively. Fourier‐transform infrared spectroscopy (FTIR) analysis showed bands at 1643 cm^?1 and 1550 cm^?1 in the spectrum of M2005‐grafted CNCs, which qualitatively indicated the amide bond formation. In addition, the morphology and the zeta potential of modified CNCs ensured their homogeneity, stability, and surface degree of charge. In spite of a decrease in the solubility in water of the modified crystals, the procedure of chemical modification used avoided any variation in their crystalline structure and thermal stability. Then, the incorporation of sulfated, oxidized, or M2005‐grafted CNCs in matrices of TPS and P(3HB) allowed to produce reinforced nanocomposite films, with excellent barrier properties. Therefore, the chemical compatibility between CNCs and the polymer matrices is essential to produce attractive nanocomposites with improved mechanical properties for industrial applications.     

Improved synthesis of beta-D-6-methylpurine riboside and antitumor effects of the beta-D- and alpha-D-anomers

6-Methylpurine-beta-D-riboside (beta-D-MPR) has been synthesized by coupling 6-methylpurine and 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribose using conditions that produce the beta-D-anomer exclusively. The in vitro antitumor effects of beta-D-MPR and 6-methyl-purine-alpha-D-riboside (alpha-D-MPR) in five human tumor cell lines showed that beta-D-MPR was highly active (IC(50) values ranging from 6 to 34 nM). alpha-D-MPR, although less active than beta-D-MPR, also exhibited significant antitumor effects (IC50 values ranging from 1.47 to 4.83 microM).     

MEMS-based sample preparation for molecular diagnostics

Completion of the Human Genome Project is driving the rapid development of molecular diagnostics in the laboratory. To accelerate the penetration of genetic tests and other nucleic acid-based tests into clinical markets, simple, compact, automatic sample-preparation systems for molecular diagnostics must be developed. Microelectromechanical systems (MEMS) is a promising approach for the development of automated sample preparation for the clinical laboratory or point-of-care setting. This review discusses MEMS-based components that could be applied to the different stages of the sample-preparation process such as cell separation, nucleic acid purification, and nucleic acid amplification. Examples of functional component integration are given. Issues discussed include partitioning of functions between the instrument and disposable unit, methods of propulsion of fluids and particles, vapor and liquid barriers, and sample size. Although further evaluation and development are needed to provide practical solutions to some of these issues, we conclude that MEMS-based components might contribute to some components in a sample-preparation system consisting of modular instruments and disposable units, but will not provide a generic or a totally integrated solution.