Enantio-complementary deracemization of (±)-2-hydroxy-4-phenylbutanoic acid and (±)-3-phenyllactic acid using lipase-catalyzed kinetic resolution combined with biocatalytic racemization

Deracemization of (±)-3-phenyllactic acid (1) and (±)-2-hydroxy-4-phenylbutanoic acid (2) was accomplished by lipase-catalysed kinetic resolution coupled to biocatalytic racemization of the non-reacting substrate enantiomers using Lactobacillus paracasei DSM 20008. Cyclic repetition of this sequence led to a single enantiomeric product from the racemate. Access to both enantiomers was achieved by switching between lipase-catalysed acyl-transfer and ester hydrolysis reactions. Both products constitute important building blocks for virus protease- and ACE-inhibitors, respectively.     

Efficient "total" extraction of perfluorooctanoate from polytetrafluoroethylene fluoropolymer

To determine the optimum conditions for the complete extraction of perfluorooctanoate (PFO) from polytetrafluoroethylene fluoropolymers, sample preparation and pressurized solvent extraction (PSE) conditions were investigated. Solvent extraction temperature, solvent residence time, relaxation time between extractions, and the effects of heating before PSE showed that methanol at 150 degrees C extraction temperature and a 12 min solvent residence time were the most efficient conditions. Preheating the polymer before extraction at 150 degrees C for 24 h significantly enhanced the quantity of PFO removed. Heating above 150 degrees C resulted in loss of PFO. PFO was determined by liquid chromatography with tandem mass spectrometry.     

A new family of ruthenium(II) polypyridine complexes bearing 5-aryltetrazolate ligands as systems for electrochemiluminescent devices

A new family of mono- and dinuclear ruthenium polypyridyl complexes containing 5-aryltetrazolate ligands such as the deprotonated form of 4-(1H-tetrazol-5-yl)benzonitrile (4-TBNH) and bis(1H-tetrazol-5-yl)benzene (BTBH(2)) have been synthesized and thoroughly characterized. The reactivity of the mononuclear species toward different electrophiles such as H(+) and CH(3)(+) has been investigated, and the effects of the resulting regioselective electrophilic attacks on the electronic and structural properties of the tetrazolate ligand have been studied by NMR ((1)H, (13)C) spectroscopy and X-ray crystal structures. Absorption and emission spectroscopy, together with an electrochemical and UV-vis-NIR spectroelectrochemical investigation of the uncoordinated ligand and complexes, has been performed, highlighting a rather good luminescence efficiency and a poor bridge-mediated electronic communication between the metal centers of the dinuclear complexes. The electrogenerated chemiluminescence (ECL) of the dinuclear species has been explored, and for one of these, an exceptionally high ECL efficiency has been observed, comparable to that of [Ru(bpy)(3)](2+), which is considered a standard in ECL studies.     

Polymorphic behavior in protein-surfactant mixtures: the water-bovine serum albumin-sodium taurodeoxycholate system

Mixtures containing water, bovine serum albumin (BSA), and sodium taurodeoxycholate (NaTDC), a component of the bile in mammals, have been investigated in a wide range of composition and pH. Depending on the concentration of both solutes and the pH, solutions, precipitates, and gels are formed. Under spontaneous pH conditions, the transport properties in dilute solutions indicate the occurrence of significant interactions between BSA and the surfactant. Conversely, acidic media favor the formation of nonsoluble protein-surfactant complexes, with subsequent precipitation. The nucleation kinetics of the protein-surfactant complexes in solid form and the related precipitation processes can be slow or fast, depending on the overall solute content and the mole ratio. At high concentrations, a gel, extending on both sides of the charge neutralization line, and two-phase regions are observed. Gels shrink in open air and swell in the presence of excess water. Depending on concentration and temperature, the gels transform from an essentially liquidlike behavior to that peculiar to true gels (when G' > or = G'). The thermal gelation threshold, the temperature above which G' > or = G', depends on BSA and NaTDC content and is concomitant to moderate heat effects, inferred by differential scanning calorimetry (DSC). The above data also indicate that the protein thermal denaturation in the gel is shifted to higher temperatures compared to water. Such a stabilizing effect is presumably related to the occurrence of both electrostatic and hydrophobic interactions with NaTDC. Water self-diffusion in the gels is slightly slower than that in the bulk and poorly sensitive to composition: it is about 65% the value of neat H2O in a wide concentration range, irrespective of the BSA, or NaTDC, concentration. A peculiar behavior is also observed in 23Na longitudinal and transverse relaxation rates. The T1 and T2 values, measured at 105.75 MHz on BSA-NaTDC gels, indicate that the motions determining the NMR relaxation of the sodium ions in the hydration layer of the protein-surfactant aggregates are not slow, having frequencies comparable with the Larmor one. The above properties, especially the rheological and the spectroscopic ones, are important for understanding the behavior of gels based on protein-surfactant mixtures.     

Boundary Observability and Stabilization for Westervelt Type Wave Equations without Interior Damping

In this paper we show boundary observability and boundary stabilizability by linear feedbacks for a class of nonlinear wave equations including the undamped Westervelt model used in nonlinear acoustics. We prove local existence for undamped generalized Westervelt equations with homogeneous Dirichlet boundary conditions as well as global existence and exponential decay with absorbing type boundary conditions.     

Sampling inequalities for infinitely smooth functions,with applications to interpolation and machine learning

Sampling inequalities give a precise formulation of the fact that a differentiable function cannot attain large values if its derivatives are bounded and if it is small on a sufficiently dense discrete set. Sampling inequalities can be applied to the difference of a function and its reconstruction in order to obtain (sometimes optimal) convergence orders for very general possibly regularized recovery processes. So far, there are only sampling inequalities for finitely smooth functions, which lead to algebraic convergence orders. In this paper, the case of infinitely smooth functions is investigated, in order to derive error estimates with exponential convergence orders.     

Towards Targeted Drug Delivery by Covalent Ligand-Modified Polymeric Nanocontainers

Here we present a novel strategy for specific cellular targeting of polymeric nanocontainers by using self-assembly of block copolymers consisting of either Polydimethoxysiloxane-b-Polymethyloxazoline-b-Polydimethoxysiloxane (PDMS-b-PMOXA-b-PDMS) or functionalized PDMS-b-PMOXA-b-PDMS. Covalent functionalization of the above copolymer was accomplished using either the fluorescent dye sulforhodamine B or a poly-guanosin ligand, the latter by using the Huisgen 1,3-dipolar cycloaddition. The success of the covalent modification of the block copolymer has been determined by studying functionalized sulforhodamine B by NMR and fluorescence correlation spectroscopy. The covalent click chemistry approach leads to efficiently functionalized polymeric nanocontainers which enables specific uptake by activated macrophages overexpressing the scavenger receptor A1.     

Proteomic biomarkers in plasma that differentiate rapid and slow decline in lung function in adult cigarette smokers with chronic obstructive pulmonary disease (COPD)

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of morbidity and mortality in the United States and cigarette smoking is a primary determinant of the disease. COPD is characterized by chronic airflow limitation as measured by the forced expiratory volume in one second (FEV₁). In this study, the plasma proteomes of 38 middle-aged or older adult smokers with mild to moderate COPD, with FEV₁ decline characterized as either rapid (RPD, n?=?20) or slow or absent (SLW, n?=?18), were interrogated using a comprehensive high-throughput proteomic approach, the accurate mass and time (AMT) tag technology. This technology is based upon a putative mass and time tag database (PMT), high-resolution LC separations and high mass accuracy measurements using FT-ICR MS with a 9.4-T magnetic field. The peptide and protein data were analyzed using three statistical approaches to address ambiguities related to the high proportion of missing data inherent to proteomic analysis. The RPD and SLW groups were differentiated by 55 peptides which mapped to 33 unique proteins. Twelve of the proteins have known roles in the complement or coagulation cascade and, despite an inability to adjust for some factors known to affect lung function decline, suggest potential mechanistic biomarkers associated with the rate of lung function decline in COPD. Whether these proteins are the cause or result of accelerated decline will require further research.     

HPLC/DAD/MS and antioxidant activity of isoflavone-based food supplements

Isoflavones are polyphenolic compounds found mainly in legumes the benefits of which have been widely studied and attributed in particular to their phytoestrogenic activity. The aim of this study was to evaluate the quali-quantitative composition of food supplements based on soy isoflavones (Glycine max L.) and red clover (Trifolium pratense). Six commercial food supplements (five soy-based and one red clover-based) were analyzed by HPLC/DAD/MS. Genistein, daidzein, glycitein, biochanin A and formononetin derivatives (glycosides and acylglycosides) were identified in the analyzed samples. Also the antiradical activities (towards the DPPH* radical) and Fe2+ chelating abilities were compared.