Frame properties of wave packet systems in L^2({\mathbb R}^d)

Extending work by Hernandez, Labate and Weiss, we present a sufficent condition for a generalized shift-invariant system to be a Bessel sequence or even a frame for . In particular, this leads to a sufficient condition for a wave packet system to form a frame. On the other hand, we show that certain natural conditions on the parameters of such a system exclude the frame property.      

HPMA copolymer-doxorubicin-gadolinium conjugates: synthesis, characterization, and in vitro evaluation

This study describes the synthesis, characterization, and in vitro evaluation of N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer-gadolinium (Gd)-doxorubicin (Dox) conjugates. Copolymers of HPMA were derivatized to incorporate side chains for Gd chelation and Dox conjugation. The conjugates were characterized by their side chain contents, T(1) relaxivity (r(1)), stability, and in vitro cytotoxicity. High stability and relaxivity of these conjugates coupled with low toxicity show their potential for monitoring the in vivo fate of HPMA-based drug delivery systems by magnetic resonance imaging techniques.     

Molecular simulation of protein dynamics in nanopores. I. Stability and folding

Discontinuous molecular dynamics simulations, together with the protein intermediate resolution model, an intermediate-resolution model of proteins, are used to carry out several microsecond-long simulations and study folding transition and stability of alpha-de novo-designed proteins in slit nanopores. Both attractive and repulsive interaction potentials between the proteins and the pore walls are considered. Near the folding temperature T(f) and in the presence of the attractive potential, the proteins undergo a repeating sequence of folding/partially folding/unfolding transitions, with T(f) decreasing with decreasing pore sizes. The unfolded states may even be completely adsorbed on the pore's walls with a negative potential energy. In such pores the energetic effects dominate the entropic effects. As a result, the unfolded state is stabilized, with a folding temperature T(f) which is lower than its value in the bulk and that, compared with the bulk, the folding rate decreases. The opposite is true in the presence of a repulsive interaction potential between the proteins and the walls. Moreover, for short proteins in very tight pores with attractive walls, there exists an unfolded state with only one alpha-helical hydrogen bond and an energy nearly equal to that of the folded state. The proteins have, however, high entropies, implying that they cannot fold onto their native structure, whereas in the presence of repulsive walls the proteins do attain their native structure. There is a pronounced asymmetry between the two termini of the protein with respect to their interaction with the pore walls. The effect of a variety of factors, including the pore size and the proteins' length, as well as the temperature, is studied in detail.     

Biomimetic electrochemical sensor based on molecularly imprinted polymer for dicloran pesticide determination in biological and environmental samples

Dicloran pesticide is used to inhibit the fungal spore germination for different crops. Because of the increasing application of pesticides, reliable and accurate analytical methods are necessary. The aim of this work is designing the highly selective sensor to determine the dicloran in biological and environmental samples. Multi-walls carbon nanotubes and a molecularly imprinted polymer (MIP) were used as modifiers in the sensor composition. A dicloran MIP and a nonimprinted polymer (NIP) were synthesized and applied in the carbon paste electrode. After the optimization of electrode composition, it was used to determine the concentration of analyte. Parameters affecting the sensor response were optimized, such as sample pH, electrolyte concentration and its pH, and the instrumental parameters of square wave voltammetry. The MIP-CP electrode showed very high recognition ability in comparison with NIP-CP. The obtained linear range was 1 × 10^?6 to 1 × 10^?9 mol L^?1. The detection limit was 4.8 × 10^?10 mol L^?1. This sensor was used to determine the dicloran in real samples (human urine, tap and river water samples) without special sample preparation before analysis. All important parameters were optimized, improving the sensor response considerably.     

Optimization of solid phase microextraction procedure for determination of paraquat using reduction process

Headspace solid phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry was developed for the determination of paraquat in urine. The volatile product resulting from reduction of paraquat by sodium borohydride–nickel chloride was used for HS-SPME. The calibration curve was linear from 10–1000 ng/mL and the limit of detection was 0.1 ng/mL. The optimized methods were validated using 500 and 750 ng/mL concentrations of paraquat in the spiked urine samples. The recoveries obtained in this study were 98.2% for intra-day (n = 6) and 99.2% for inter-day (n = 6), respectively, with RSD lower than 1.1%.     

Coupling Microplate-Based Antibacterial Assay with Liquid Chromatography for High-Resolution Growth Inhibition Profiling of Crude Extracts: Validation and Proof-of-Concept Study with Staphylococcus aureus

With the identification of novel antibiotics from nature being pivotal in the fight against human pathogenic bacteria, there is an urgent need for effective methodologies for expedited screening of crude extracts. Here we report the development and validation of a simple and dye-free antimicrobial assay in 96-well microplate format, for both determination of IC₅₀ values and high-resolution inhibition profiling to allow pin-pointing of bioactive constituents directly from crude extracts. While commonly used antimicrobial assays visualize cell viability using dyes, the developed and validated assay conveniently uses OD₆₀₀ measurements directly on the fermentation broth. The assay was validated with an investigation of the inhibitory activity of DMSO against Staphylococcus aureus, temperature robustness, interference by coloured crude extracts as well as inter-day reproducibility. The potential for high-resolution S. aureus growth inhibition profiling was evaluated on a crude extract of an inactive Alternaria sp., spiked with ciprofloxacin.     

Performance evaluation of Alizarin extraction from aqueous solutions in a microfluidic system

This research has been conducted to study extraction of an anionic dye, Alizarin Red S (ARS), from the aqueous phase into the organic phase in a T-junction microchannel. The organic phase included Aliquat 336 and 1-octanol. Equal volumetric flow rates of aqueous and organic phases were adjusted in all the experiments. Designing the experiments and analyzing of the parameters that affect the extraction percentage of ARS were carried out using response surface methodology. The parameters were feed pH, feed concentration, extractant concentration and flow rate of aqueous and organic phases. The maximum extraction percentage of 98.7 was obtained at the feed pH of 3, feed concentration of 5000 mg L^?1, extractant concentration of 4 vol.% and flow rate of 2.5 mL min^?1. Under the optimum conditions obtained from the experimental design analysis, ARS extraction was performed in a batch system, too. The two-phase contact times to reach the extraction percentage of 98.7 in the microchannel and batch system were 2.4 s and 5.5 min, respectively.     

Influence of growth phase on the essential oil composition and antimicrobial activities of Satureja hortensis

The variations in quantity and quality of essential oils (EOs) from the aerial parts of cultivated Satureja hortensis were determined at different stages of harvesting. The EOs of air-dried samples were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry (GC/MS). The antimicrobial activity of the EOs was investigated by broth microdilution methods. The amount of EOs (w/w, %) were 2.3, 2.5, 2.0, and 1.8% at floral budding, full flowering, immature fruit, and ripened fruit stages, respectively. gamma-Terpinene was the major compound of the EO at all developmental stages, except the ripened fruit stage when it was replaced by carvacrol (46.4%). The EOs exhibited strong antibacterial activities against the tested bacteria. Moreover, the EOs either inhibited or killed the examined yeasts at concentrations ranging from 0.03-8.0 microL/mL. Considering the wide range of antimicrobial activities of the examined EOs, they might have potential to be used in the management of infective agents.     

A New Algorithm for Estimating Three-Phase Relative Permeability from Unsteady-State Core Experiments

We present a new history matching method based on a Genetic Algorithm to estimate three-phase k _r (relative permeability) from unsteady-state coreflood experiments. In this method, relative permeabilities (k _r) are represented by quadratic B-Spline functions. Adjustable coefficients in k _r functions are changed in an iterative process to minimize an objective function. The objective function is defined as the difference between the measures and simulated values of the pressure drop across the core and fluids recovery during the experiment. One of the main features of this approach is that water and gas relative permeabilities (k _rw and k _rg) are assumed to be functions of two independent saturations as opposed to most of the existing empirical k _r models in which k _rw and k _rg are assumed to be only dependent of their own saturations. Another important aspect of this algorithm is that it considers inequality constrains to ensure that physically acceptable k _r curves are maintained throughout the iterative optimization process. A three-phase coreflood simulator has been developed based on this methodology that generates best k _r values by matching experimental data. The integrity of the developed software was first successfully verified by using two sets of experimental three-phase k _r data published in the literature. Then, the results of some three-phase coreflood experiments carried out in our laboratory were used to obtain three-phase k _r curves by this approach.     

Synthesis and characterization of 2-phenylaniline cyclopalladated complexes

Reaction of the dinuclear complex [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}Cl]₂ (1) with ligands (L = 4-picoline, sym-collidine) gave the six-membered palladacycles [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}Cl(L)] (2). The complex 1 reacted with AgX (X = CF₃SO₃, BF₄) and bidentate ligands [L–L = phen (phenanthroline), dppe (bis(diphenylphosphino)ethane), bipy(2,2′-bipyridine) and dppp (bis(diphenylphosphino)propane)] giving the mononuclear orthopalladated complexes [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}(L–L)] (3) [L–L = phen, dppe, bipy and dppp]. These compounds were characterized by physico-chemical methods, and the structure of [Pd{κ2-N2′,C1-2-(2′-NH₂C₆H₄)C₆H₄}Cl(L)] (L = sym-collidine) was determined by single-crystal X-ray analysis.