Axisymmetric Fractional Diffusion with Mass Absorption in a Circle under Time-Harmonic Impact

The axisymmetric time-fractional diffusion equation with mass absorption is studied in a circle under the time-harmonic Dirichlet boundary condition. The Caputo derivative of the order 0<α≤2 is used. The investigated equation can be considered as the time-fractional generalization of the bioheat equation and the Klein–Gordon equation. Different formulations of the problem for integer values of the time-derivatives α=1 and α=2 are also discussed. The integral transform technique is employed. The outcomes of numerical calculations are illustrated graphically for different values of the parameters.     

Synthesis and characterization of new mesomorphic octakis(alkylthio)-substituted lead phthalocyanines and their films

The syntheses of new octakis (alkylthio)-substituted phthalocyanines of Pb(II) (1a and 2a) are described. These compounds are very soluble in most common organic solvents. They have been fully characterized using elemental analysis, NMR, infrared and UV–Vis spectroscopy. The mesogenic properties of these new materials were studied by differential scanning calorimetry and optical microscopy. These phthalocyanine derivatives are liquid at room temperature and form columnar-hexagonal (Col_h) mesophases below −10 °C. It has been indicated that the addition of methylene bridges to the phthalocyanine (Pc) core increases the clearing point temperatures. Also, the coordination of Pb²⁺ with the phthalocyanine core decreases the clearing point temperatures and the liquid crystal phase transition temperatures. Thin films of octakis(alkylthio)-substituted Pb(II) phthalocyanines 1a and 2a were prepared by the method of spin-coating. To obtain films with an ordered structure the film of 1a was slowly cooled from room temperature down to −10 °C. Sandwich structures of the form Au/PbPc(1a)/Au were prepared for the investigation of their electrical properties. It was shown that a slowly cooled Au/PbPc(1a)/Au structure demonstrates repeatable and stable electrical switching behaviour for applied bias voltages between −1 V and +1 V.     

Compressed-air flow control system

We present the construction and operation of a compressed-air driven flow system that can be used for a variety of microfluidic applications that require rapid dynamic response and precise control of multiple inlet streams. With the use of inexpensive and readily available parts, we describe how to assemble this versatile control system and further explore its utility in continuous- and pulsed-flow microfluidic procedures for the synthesis and analysis of microparticles.     

Resolution of 5- and 6-Membered P-Heterocycles: Racemic and Optically Active Platinum(II)-3-Phospholene Complexes

Abstract

Methods were developed for the resolution of several five- and six-membered phosphorus heterocycles (1c-e, 2, 4). It was investigated if the optical activity is preserved during the 1a→2→3→4 reaction sequence. Racemic and optically active 1b-e 3-phospholene 1-oxides were converted to the corresponding platinum-complexes (10b-e), which are potential catalysts.     

Studies on the Structure and Properties of Membrane Phospholipase A1 Inclusion Bodies Formed at Low Growth Temperatures Using GFP Fusion Strategy

The effect of cultivation temperatures (37, 26, and 18 °C) on the conformational quality of Yersinia pseudotuberculosis phospholipase A₁ (PldA) in inclusion bodies (IBs) was studied using green fluorescent protein (GFP) as a folding reporter. GFP was fused to the C-terminus of PldA to form the PldA-GFP chimeric protein. It was found that the maximum level of fluorescence and expression of the chimeric protein is observed in cells grown at 18 °C, while at 37 °C no formation of fluorescently active forms of PldA-GFP occurs. The size, stability in denaturant solutions, and enzymatic and biological activity of PldA-GFP IBs expressed at 18 °C, as well as the secondary structure and arrangement of protein molecules inside the IBs, were studied. Solubilization of the chimeric protein from IBs in urea and SDS is accompanied by its denaturation. The obtained data show the structural heterogeneity of PldA-GFP IBs. It can be assumed that compactly packed, properly folded, proteolytic resistant, and structurally less organized, susceptible to proteolysis polypeptides can coexist in PldA-GFP IBs. The use of GFP as a fusion partner improves the conformational quality of PldA, but negatively affects its enzymatic activity. The PldA-GFP IBs are not toxic to eukaryotic cells and have the property to penetrate neuroblastoma cells. Data presented in the work show that the GFP-marker can be useful not only as target protein folding indicator, but also as a tool for studying the molecular organization of IBs, their morphology, and localization in E. coli, as well as for visualization of IBs interactions with eukaryotic cells.     

Imaging of Spontaneous Canine Mammary Tumors Using Fluorescent Contrast Agents

We present near-infrared frequency-domain photon migration imaging for the lifetime sensitive detection and localization of exogenous fluorescent contrast agents within tissue-simulating phantoms and actual tissues. We employ intensity-modulated excitation light that is expanded and delivered to the surface of a tissue or tissue-simulating phantom. The intensity-modulated fluorescence generated from within the volume propagates to the surface and is collected using a gain-modulated image-intensified charge-coupled device camera. From the spatial values of modulation amplitude and phase of the detected fluorescent light, micromolar volumes of diethylthiatricarbocyanine iodide (tau = 1.17 ns) and indocyanine green (ICG) (tau = 0.58 ns) embedded 1.0 cm deep in a tissue phantom are localized and discriminated on the basis of their lifetime differences. To demonstrate the utility of frequency-domain fluorescent measurements for imaging disease, we image the fluorescence emitted from the surface of in vivo and ex vivo canine mammary gland tissues containing lesions with preferential uptake of ICG. Pathology confirms the ability to detect spontaneous mammary tumors and regional lymph nodes amidst normal mammary tissue and fat as deep as 1.5 cm from the tissue surface.     

Ramsey’s theorem for trees: the polarized tree theorem and notions of stability

We formulate a polarized version of Ramsey’s theorem for trees. For those exponents greater than 2, both the reverse mathematics and the computability theory associated with this theorem parallel that of its linear analog. For pairs, the situation is more complex. In particular, there are many reasonable notions of stability in the tree setting, complicating the analysis of the related results.     

A new multicomponent reaction catalyzed by a [Lewis Acid](+)[Co(CO)(4)](-) catalyst: stereospecific synthesis of 1,3-oxazinane-2,4-diones from epoxides, isocyanates, and CO

The use of mechanistic information to develop a new, catalytic multicomponent reaction is described. The complex [(salph)Al(THF)2]+[Co(CO)4]- (1, salph = N,N'-o-phenylenebis(3,5-di-tert-butylsalicylideneimine), THF = tetrahydrofuran), which is known to carbonylate epoxides, aziridines, and beta-lactones, was used to catalyze the synthesis of 1,3-oxazinane-2,4-diones from epoxides, isocyanates, and CO. Under optimized conditions, the reaction was both selective and high-yielding. 1,3-Oxazinane-2,4-diones were synthesized from a variety of epoxides and isocyanates, including some epoxides that do not undergo simple ring-expansion carbonylation. The best results were obtained using highly electrophilic isocyanates. The mechanism of the multicomponent reaction was investigated using labeling and stereochemistry, and the data obtained were consistent with the 1-catalyzed formation of beta-lactone and 1,3-oxazinane-2,4-dione from a common intermediate.     

Photophysics of aminoxanthone derivatives and their application as binding probes for DNA

Xanthones with amino substituents were synthesized to diminish the photoreactivity of the xanthone chromophore with DNA, with the objective of using these molecules to study their binding dynamics with DNA. The aminoxanthones showed a strong solvatochromic effect on their singlet and triplet excited-state photophysics, where polar solvents led to a decrease of the energies for the excited states. Quenching of the triplet excited states by nitrite anions was used to determine the binding dynamics, and a residence time in the microsecond time domain was estimated for the bound 2-aminoxanthone with DNA. The quenching experiments performed showed that this methodology will not be applicable to study the binding dynamics of a wide variety of guests with DNA.     

Multiplex PCR with minisequencing as an effective high-throughput SNP typing method for formalin-fixed tissue

Extensive collections of formalin-fixed paraffin-embedded (FFPE) tissues exist that could be exploited for genetic analyses in order to provide important insights into the genetic basis of disease or host/pathogen cointeractions. We report here an evaluation of a 44 SNP multiplex genotyping method, multiplex PCR with minisequencing (MPMS), on 92 DNA extractions performed on six archival FFPE samples of variable DNA quality, which date between 9 and 25 years old. On the three extracts with highest quality, we found the assay efficiency to be near 100%. However, the efficiency of the lowest quality extracts varied significantly. In this study, we demonstrate that although direct measures of DNA concentration in the extracts provide no useful information with regard to subsequent MPMS success, the success of the assay can be determined to some degree a priori, through initial screening of the DNA quality using a simple quantitative real-time PCR (qPCR) assay for nuclear DNA, and/or an assay of the maximum PCR amplifiable size of nuclear DNA. MPMS promises to be of significant use in future genetic studies on FFPE material. It provides a streamlined approach for retrieving a large amount of genetic information using simple, single reactions and minute amounts of archival tissue/DNA. In the light of this evidence, we suggest that the systematic screening of FFPE collections may in the future provide valuable insights into the past.