Carrier-mediated transport of yttrium(III) through a supported liquid membrane containing TOPO in n-dodecane

Transport of yttrium(III) from nitrate medium through liquid membrane containing tri-n-octyl-phosphine oxide (TOPO) in n-dodecane, supported on a nucleoporous filter, into a strip solution with ethylenediaminetetraacetic acid (EDTA) has been studied. The kinetic dependences of transport were obtained and compared with a model, resulting in calculation of permeability coeffients and initial fluxes of yttrium. The influence of salting-out agent, initial metal and nitric acid concentrations in the feed, and of concentration of carrier in membrane are discussed.     

Order from Chaos: Self‐Assembly of Nanoprism from a Mixture of Tetratopic Terpyridine‐Porphyrin Conformers

Porphyrins have been widely used in the self‐assembly of metallo‐supramolecules. In this study, we introduced 2,2':6,2"‐terpyridine (tpy) into a porphyrin core to synthesize a tetratopic building block with multiple conformers. During the self‐assembly with Zn(II), such a mixture of conformers was able to form a discrete nanoprism with all building blocks in one conformation. Detailed characterizations, including NMR, ESI‐MS and traveling‐wave ion mobility‐mass spectrometry (TWIM‐MS), all supported the formation of the desired assemblies. AFM and TEM further confirmed the dimensions of assembled nanoprisms. Moreover, the photophysical properties of the ligands and complexes were noticeably different depending upon size and metal ion center.     

Synthesis of novel tryptamine and β-carboline derivatives via palladium-catalyzed reaction of bromotryptamine with organic boronic acids

New tryptamine 5, 7 and β-carboline derivatives 3 were preparated by palladium-catalyzed coupling reaction of 5-bromotryptamine 1 with aryl boronic acids. Dedicated to Professor András Lipták on his 70^th birthday.     

Hierarchical assembly of homochiral porous solids using coordination and hydrogen bonds

A family of homochiral metal carboxylate coordination polymers have been synthesized by treating 2,2'-dihydroxy-1,1'-binaphthalene-6,6'-dicarboxylic acid (H(2)BDA) with metal salts at elevated temperatures. BDA ligands link adjacent metal centers to form 1D coordination polymeric chains using the carboxylate functionality, while the hydroxyl groups of BDA ligands form H-bonds with carboxylate oxygen atoms to link 1D coordination polymeric chains into open frameworks of higher dimensionality. We also present evidence for the important role played by H-bonds in the stabilization of open framework structures which allows for the hierarchical assembly of chiral porous solids.     

Rapid,sensitive fluorimetric assay for proteases using fluorescein-labelled albumin coupled to Fractogel activated with 2-fluoro-1-methylpyridinium salt in flow-injection analysis

A rapid and sensitive flow-injection method is described for the fluorimetric determination of the proteolytic activity of a number of enzymes. The substrate, fluorescein-labelled bovine serum albumin coupled to a 2-fluoro 1-methylpyridinium salt-activated Fractogel support, is packed in a small reactor (35 × 2 mm i.d.) and inserted into a flow manifold. Under the reaction conditions the amount of fluorescein released from enzymatic cleavage of the substrate is found to be directly proportional to the activity of the proteolytic enzyme. Sample throughput is 30–35 h^?1. The calibration range for trypsin is linear up to at least 0.35 μg ml^?1. Linear responses were also obtained for otherproteolytic enzymes such as papain, chymotrypsin, ficin and bromelain.     

New guaianolides from Berlandiera Pumila and B. Texana,and the X-ray crystal structure of pumilin

The isolation and structure determination of two new guaianolides, pumilin and its 2,3-epoxide, from Berlandiera pumila and B. texana are reported. The structure of pumilin was determined from nmr and mass spectral data, and from an X-ray single crystal study; the structure of the epoxide was found by comparison of nmr spectra. Pumilin is shown to be a Δ¹⁽¹⁰⁾-cis-guaianolide with a cyclopentenone ring attached to C1 and C5, and an α-methylene-γ-lactone ring trans-fused to C6 and C7. The absolute configuration was inferred from spectral considerations and knowledge of previous structural determinations. The cd spectrum of pumilin exhibits a negative Cotton effect, and the lactone chromophore has left-handed chirality. The cyclo-heptene ring is in the chair configuration, with the lactone a half-chair and the cyclopentenone essentially planar. Crystals are orthorhombic, a = 7.065, b = 13.652, c = 19.586 Å, space group P2₁2₁2₁, Z = 4, and the final R value is 3.9%. The crystal structure is strengthened by an O···O hydrogen bond linking the molecules into infinite chains.     

PHOTOBIOLOGICAL ACTIVITY OF 3,4''-DIMETHYL-8-METHOXYPSORALEN, A LINEAR FUROCOUMARIN WITH UNUSUAL DNA-BINDING PROPERTIES

The furocoumarin derivative 3,4'-dimethyl-8-methoxypsoralen (DMe-8-MOP) exhibits remarkable antiproliferative activity, but is devoid of skin phototoxicity. To gain insight into this peculiar behaviour we investigated non-covalent and covalent binding of DMe-8-MOP to calf thymus DNA, along with DNA-synthesis inhibition and mutagenic activity. The non-covalent interaction of DMe-8-MOP with the nucleic acid is quite poor as shown by equilibrium dialysis, spectroscopic, chiroptical and hydrodynamic techniques. However, it exhibits relevant photobinding ability to DNA using both isolated nucleic acid samples and cellular systems. Unlike the large majority of congeners, DMe-8-MOP undergoes predominantly photochemical monoaddition to the double helical polynucleotide. Upon examination of the products obtained by enzymatic hydrolysis of DMe-8-MOP photomodified DNA, the formation of an unusual furan side adduct is proposed, which could account for the peculiar photochemical and photobiological properties of the 3,4'-dimethyl furocoumarin derivative.     

SYNTHESIS AND PHOTOBIOLOGICAL PROPERTIES OF 4-HYDROXYMETHYL-4'-METHYLPSORALEN DERIVATIVES

The synthesis and the photobiological activity of two new hydroxymethyl derivatives of psoralen namely 4-hydroxymethyl-4'-methyl- and 4-hydroxymethyl-4'-methyl-8-rnethoxypsoralen are described. Both compounds exhibited efficient photobinding to DNA and RNA. The DNA-photobinding process was investigated using different nucleic acid structures such as double-helical DNA, ribosomal RNA, bacterial DNA and DNA organized in the nucleosomal arrangement. The test derivatives were able to induce cross-links to a similar extent as 8-methoxypsoralen (8-MOP), used as a reference photochemotherapeutic drug. In contrast to 8-MOP, they produced relatively high levels of ^lO₂. Most photobiological effects (DNA synthesis inhibition, T₂ phage sensitization, inhibition of tumor transmitting capacity) showed a good correlation with the extent of covalent photoaddition. On the other hand, the new 4-hydroxymethylpsoralens were unable to induce skin erythema, in striking contrast with 8-MOP. Thus, neither cross-linking of the nucleic acid nor ¹O₂ production were coupled with skin phototoxicity in this class of compounds. The new derivatives appear to represent an important beginning to development of new active photochemotherapeutic agents devoid of undesired phototoxic side effects.     

Adaptive encoding of zoomable video streams based on user access pattern

Zoomable video allows users to selectively zoom and pan into regions of interest within the video for viewing at higher resolutions. Such interaction requires dynamic cropping of RoIs on the source video. We have previously explored two different ways of encoding and transmitting video to support dynamic RoI cropping: (i) Monolithic streaming uses a standard video encoder to encode the video. When an RoI is requested, the bits belonging to the RoI along with other bits required to decode the RoIs (due to encoding dependencies) are transmitted. (ii) Tile streaming divides regions in the standard video into rectangular tiles that are encoded independently. The tiles that intersect with a requested RoI are transmitted. In this paper, we consider how the bandwidth needed to transmit the RoIs can be reduced by carefully encoding the source video for each of the two encoding schemes. The goal is to support bandwidth efficient compressed domain RoI cropping in the context of virtual zoom and pan by tuning encoder parameters. Our key idea is to exploit user access patterns to the RoIs, and encode different regions of the video with different encoding parameters based on the popularity of the region. We show that our encoding method can reduce the expected bandwidth by up to 43% in the test video sequence which we have used.     

Estimation of radon and thoron caused dose at exraction and processing sites of mineral sand mining area in Vietnam (HA TINH province)

Mineral sands are mined in several countries to supply to the titanium and zircon producing industries. Coastal black mineral sands usually contain, besides ilmenite (FeTiO₃) and rutile (TiO₂), radioactive minerals such as zircon (ZrSiO₄) and monazite (RePO₄). Radon and thoron activity concentration originated from natural radioactive contents of the black mineral sand was monitored at the extraction and processing for black minerals in the coastal areas of Ha Tinh Province, one of the around 40 coastal mineral sand deposits in Vietnam. The survey was carried out with the Raduet chambers made by Radosys Ltd—Hungary. The obtained results for 25 investigated points show that the measured values are not high in the residential houses and in case of the sand extraction site as well. At the titanium processing plant the measured values were higher than outside the facility (Radon: 18–55 Bq/m³ with average of 34 Bq/³ and Thoron 33–118 Bq/m³ with average of 58 Bq/m³) but still comparable to the average concentration of the world published by UNSCEAR. The typical outdoor levels of radon and thoron gas are each of the order of 10 Bq/m³. Although the radon concentrations were low in the zircon and titanium processing plants, the thoron concentrations in the houses for separating rutile and zircon were very high. At zircon processing factory, the thoron concentration could reach 2,931 Bq/m³ and the estimated annual effective dose would be 21.4 mSv/a. Intervention has to be taken in order to reduce the thoron level in this factory since the level of thoron and its progenies corresponding to an annual occupational effective dose is beyond the action level of 6 mSv/a.