Reentrant phase behavior in systems with density-induced tunneling

We show that correlations in strongly interacting many-particle systems can create quantum decoherence, leading to a mechanism of dissipation that does not rely on an external source. Using analytical methods, we study a bosonic many body system in two dimensions, with extended interactions between particles. We show that, as expected, the system can be driven out of a coherent state. Surprisingly, when the interaction strength is sufficiently large, the system reenters the superfluid phase even after coherence is lost. The breakdown of quantum coherence is a certainty, but interpreting the process correctly relies on understanding and preserving the nature of the coupling between the constituents of the many particle system. The methods used provide a natural cutoff point at the critical temperature, where superfluidity breaks down.

A Novel Strategy for the Synthesis of Amphiphilic and Thermoresponsive Poly(N-isopropylacrylamide)-b-Polystyrene Block Copolymers via ATRP

A new synthetic approach is presented for the preparation of Poly(N-isopropylacrylamide-block-styrene) PNIPAM-b-PS via an Atom Transfer Radical Polymerization (ATRP) technique. The proposed method is based on application of 2-chloro-N-(2-hydroxyethyl)propanamide (NCPAE) as a bifunctional initiator, which enables ATRP of two monomers, differing in activity and polarity, into two stages. The synthesized copolymer molecules contain two well-defined polymer chains connected by a linker, which is a derivative of the proposed initiator. Using NCPAE led to PNIPAMs with well-planned molecular weight, low polydispersities (PDI=1.1÷1.3) and hydroxyl functionality. Activation of such blocks for initiation of styrene polymerization was performed using α-bromoisobutyryl bromide. After such a modification, the synthesized homopolymers acted as macroinitiators in ARGET ATRP and a well-defined polystyrene block, as the next one in the polymer chain was successfully formed. Both of the synthesized macromolecules, PNIPAM and PNIPAM-b-PS, exhibit a thermoresponsive behavior with explicit lower critical solution temperatures (LCST) in their aqueous solutions. The synthesized homopolymers and subsequently derived block copolymers were characterized using Size-Exclusion Chromatography, Differential Scanning Calorimetry, Dynamic Light Scattering, and NMR spectroscopy.

Advanced oxidation processes with coke plant wastewater treatment

The aim of this study was to determine the most efficient method of coke wastewater treatment. This research examined two processes - advanced oxidation with Fenton and photo-Fenton reaction. It was observed that the use of ultraviolet radiation with Fenton process had a better result in removal of impurities.

The Fenestrin Antigen in Submembrane Skeleton of the Ciliate is Proposed as a Marker of Cell Polarity during Cell Division and in Oral Replacement

Tetrahymena thermophila cells have two types of polarized morphogenesis: divisional morphogenesis and oral reorganization (OR). The aim of this research is the analysis of cortical patterns of immunostaining during cell division and in OR using previously characterized antibodies against fenestrin and epiplasm B proteins. During cell division, the anarchic field of basal body proliferation of the new developing oral apparatus (AF) showed concomitant strong binding of the fenestrin antigen and withdrawal of a signal of the epiplasm B antigen. At a specific stage, the fenestrin antigen also appeared as a character of the anterior cortex pole, with a co-localized decrease in the detected epiplasm B antigen. The fenestrin antigen also showed a polarity of duplicating basal bodies in ciliary rows. Indirect immunofluorescence and immunogold labeling experiments were performed in the absence and presence of an inhibitor of activity of serine/threonine kinases, 6-dimethylaminopurine (6-DMAP) as an inducer of the oral replacement process. In the presence of 6-DMAP, one class of cells started OR, and some others were trapped and affected in cell division. Both types of cells showed an instability of oral structures and formed enlarged primordial oral fields. These anarchic fields (AFs) bind the fenestrin antigen, with disappearance of epiplasmic antigen staining. Only one protein (about 64 kDa) is detected in western blots by the anti-fenestrin antibody and it accumulated in 6-DMAP-treated cells that are involved in uncompleted morphogenetic activity. At a defined stage of oral development, both during cell division and in OR, the fenestrin antigen served as a marker of polarity of the cell of the anterior pole character.

KIN241: a gene involved in cell morphogenesis in Paramecium tetraurelia reveals a novel protein family of cyclophilin-RNA interacting proteins (CRIPs) conserved from fission yeast to man

In this study, we report cloning, by functional complementation of the KIN241 gene involved in Paramecium cell morphogenesis, cortical organization and nuclear reorganization. This gene is predicted to encode a protein of a novel type, comprising a cyclophilin-type, peptidyl-prolyl isomerase domain, an RNA recognition motif, followed by a region rich in glutamate and lysine (EK domain) and a C-terminal string of serines. As homologues of this protein are present in the genomes of Schizosaccharomyces pombe, Caenorhabditis elegans, Drosophila melanogaster, Arabidopsis thaliana and Homo sapiens, the Kin241p predicted sequence defines a new family of proteins that we propose to call 'CRIP', for cyclophilin-RNA interacting protein. We demonstrate that, in Paramecium, Kin241p is localized in the nucleus and that deletion of some nuclear localization signals (NLSs) decreases transport of the protein into the nucleus. No Kin241-1 protein is present in mutant cells, suggesting that the C-terminal serine-rich region is responsible for protein stability.

The dynamics of filamentous structures in the apical band, oral crescent, fission line and the postoral meridional filament in Tetrahymena thermophila revealed by monoclonal antibody 12G9

The ciliate Tetrahymena thermophila possesses a multitude of cytoskeletal structures whose differentiation is related to the basal bodies - the main mediators of the cortical pattern. This investigation deals with immunolocalization using light and electron microscopy of filaments labeled by the monoclonal antibody 12G9, which in other ciliates identifies filaments involved in transmission of cellular polarities and marks cell meridians with the highest morphogenetic potential. In Tetrahymena interphase cells, mAb 12G9 localizes to the sites of basal bodies and to the striated ciliary rootlets, to the apical band of filaments and to the fine fibrillar oral crescent. We followed the sequence of development of these structures during divisional morphogenesis. The labeling of the maternal oral crescent disappears in pre-metaphase cells and reappears during anaphase, concomitantly with differentiation of the new structure in the posterior daughter cell. In the posterior daughter cell, the new apical band originates as small clusters of filaments located at the base of the anterior basal bodies of the apical basal body couplets during early anaphase. The differentiation of the band is completed in the final stages of cytokinesis and in the young post-dividing cell. The maternal band is reorganized earlier, simultaneously with the oral structure. The mAb 12G9 identifies two transient structures present only in dividing cells. One is a medial structure demarcating the two daughter cells during metaphase and anaphase, and defining the new anterior border of the posterior daughter cell. The other is a post-oral meridional filament marking the stomatogenic meridian in postmetaphase cells. Comparative analysis of immunolocalization of transient filaments labeled with mAb12G9 in Tetrahymena and other ciliates indicates that this antibody identifies a protein bound to filamentous structures, which might play a role in relying polarities of cortical domains and could be a part of a mechanism which governs the positioning of cortical organelles in ciliates.

The SM19 gene, required for duplication of basal bodies in Paramecium, encodes a novel tubulin, eta-tubulin

The discovery of delta-tubulin, the fourth member of the tubulin superfamily, in Chlamydomonas [1] has led to the identification in the genomes of vertebrates and protozoa of putative delta homologues and of additional tubulins, epsilon and zeta [2-4]. These discoveries raise questions concerning the functions of these novel tubulins, their interactions with microtubule arrays and microtubule-organising centres, and their evolutionary status. The sm19-1 mutation of Paramecium specifically inhibits basal body duplication [5] and causes delocalisation of gamma-tubulin, which is also required for basal body duplication [6]. We have cloned the SM19 gene by functional complementation and found that it encodes another new member of the tubulin superfamily. SM19p, provisionally called eta-tubulin (eta-tubulin), shows low sequence identity with the tubulins previously identified in Paramecium, namely, alpha [7], beta [8], gamma [6], delta (this work) and epsilon (P. Dupuis-Williams, personal communication). Phylogenetic analysis indicated that SM19p is not consistently grouped with any phylogenetic entity.

Characteristics of gene 28 product, the constituent of the central part of bacteriophage T4 baseplate

The phage TD gene 28 product has been partially characterized and its biological role has been examined. It was found to be a protein with a molecular size of 24 kDa which cosediments with the membrane fraction of the bacterial extracts and could only be washed out by a 0.2% sarcosyl solution. Other observations indicate that gp 28 has a majority of hydrophobic residues on its surface and forms a homotrimeric complex in the absence of other phage proteins. The product was finally identified as a baseplate structural component. Incubation of purified phage preparation in a buffer which contained active protein 28, did not affect the efficiency of the plating. However, incubation of the phage particles with specific antiserum was found to neutralize phage infectivity.

[The effect of human recombinant erythropoietin on distribution of membrane phospholipids in blood platelets of patients with uremia treated with repeated hemodialysis]

An important role in the formation of hemostasis defects in uremic patients is attributed to platelet dysfunction. An essential role in platelet structure and function is played by membrane phospholipids (PL). They are asymmetrically distributed within the platelet membrane: outer surface is composed mainly of sphingomyelin (Sph) and phosphatidylcholine (PC). During platelet activation a translocation of phosphatidylserine (PS) and phosphatidylethanolamine (PE) from inner to outer membrane surface is observed. Phosphatidylinositol (PI) is not translocated. Lipid abnormalities are common in uremic patients. According to some authors erythropoietin (EPO) has been reported to alter lipid metabolism. In our recent works a positive influence of EPO on platelet PL composition in uremic patients has been indicated. The aim of this study was the assessment of the EPO influence (applied 4000 U per week) on platelet membrane PL distribution in chronically hemodialyzed patients. The PL distribution was determined using nonpenetrating tracer (TNBS) by Vale method, and using high purified phospholipases hydrolysis according to Chap method. Our results indicate that during EPO therapy the PS, PE, Sph and PC exposition at the outer surface of platelet membrane (in patients hemodialyzed without EPO widely disturbed compared with healthy controls) approaches to normal values. These results confirm our recent observations that EPO profoundly interferes with lipid metabolism. The smaller PS exposition at the outer platelet surface during EPO treatment suggests less platelet activation, and might partially explains the positive EPO influence on platelet hemostasis.