Поглощение воды и водных растворов глинополимерными нанокомпозитами внедрения

Рассмотрено первичное и повторное поглощение воды и раствора, имитирующего жидкие отходы атомных станций, глинополимерными нанокомпозитами внедрения, синтезированными на основе бентонита. Показано, что частицы глинополимерного нанокомпозита более эффективно поглощают воду и солевые растворы по сравнению с частицами природного бентонита.Розглянуто первинне і повторне поглинання води і розчину, який імітує рідкі відходи атомних станцій, глинополімерними нанокомпозитами проникнення, синтезованими на основі бентоніту. Показано, що частинки глинополімерного нанокомпозита ефективніше поглинають воду і сольові розчини у порівнянні з частинками природного бентоніту.In many cases the use of nanocomposites is restrained by insufficient knowledge of their properties. It primarily relates to intercalated nanocomposites, especially the nano composites with particles size less than 0.6 mm, containing a significant amount of clay (>60 %). The research is focus on the study of the properties of such na nocomposites. The bentonite clay from the Cherkassy deposit comprising up to 95 % of Ca-montmorillonite was used for the synthesis of nanocomposites. The preliminary substitution of Na⁺ cations for Ca²⁺ and Mg²⁺ cations was carried out. The nanocomposites clay-polymer were obtained in the process of free radical polymerization. The nanocomposites, dried at 105 ºC with particle size of 0.4 ÷ 0.6 mm were used for experiments. The properties of the nanocomposites to take up water and solutions were studied by Enslin method. The maximum value of water uptake was 69.45 ml/g. Subsequently, the sample was dried on the filter to constant weight and repeated water uptake was examined. In this case, the result was 82 ml/g, i. e. in repeated contact with water particles absorbed by 18 % more amount water than during first water uptake. The increase in water uptake is due to nonuniform polymerization (in volume and time), which resulted in deformation of some polymer chains and only after water absorption, polymer chains have a chance to take a more low-energy position. Since this phenomenon was observed for particle size of less than 0.6 mm, it can be assumed that the crystallites or aggregates of intercalated nanocomposites clay-polymer are the sites of the beginning of acrylamide polymerization. The rate of water re-absorption was lower than in case of the primary water uptake up to period of time of 1000 min and was constant to 5000 min while the rate of primary absorption decreased substantially after 1000 min. The sorption capacity of nanocomposites for solutions simulating waste of nuclear power plants was 18 ml/g that was higher than absorption by natural bentonite (3.4 ml/g). Thus, the intercalated nanocomposites clay-polymer could be promising materials as components of the geochemical and water insulating barriers

Transitional adakite-like to calc-alkaline magmas in a continental extensional setting at La Paz Au-Cu skarn deposits, Mesa Central, Mexico: metallogenic implications

"The granodiorite intrusions with associated Cu-Au skarn mineralization of La Paz district are located in the east part of the Mesa Central of Mexico. The skarn developed at the contact between a middle Cretaceous calc-argillaceous sedimentary sequence and the magmatic intrusions. A Ag-Pb-Zn vein system postdates the intrusive-skarn assemblage. Two well defi ned fault systems (N-S and E-W) divide the La Paz district. The N-S Dolores fault, with a normal vertical displacement estimated between 500 to 1000 m, separates the western Au-Cu skarn zone from the eastern hydrothermal Ag-Pb-Zn vein system. This fault is considered to be part of the Taxco-San Miguel de Allende fault system. The U-Pb dating of the intrusives at the La Paz district clearly indicates a single emplacement event dated at ca. 37 Ma (monocrystal zircon age). This age probably represents the last post-Laramide orogenic mineralizing event known to occur in the Sierra de Catorce district. Also, four calculated discordant ages suggest the presence of greenvilian basement underneath a a thick crust (35-45 km). The chemistry of the intrusive show a certain variability in composition, but they mostly belong to the high-K calc-alkaline magmatic series. Major and trace elements relationships for the intrusives show a chemical evolution from the adakite to the island arc fi elds, and from mineralized to barren intrusives, repectively. They also suggest the importance of crustal delamination processes, and the necessity of deep cortical drains to transfer oxidized magmas and metals to surface.""Las intrusiones granodioríticas que dieron origen a un depósito de Au-Cu tipo skarn en el distrito minero de La Paz, S.L.P., se localizan en la parte oriental de la Mesa Central. El skarn se desarrolló en el contacto entre una secuencia sedimentaria calco-argílica del Cretácico medio y los intrusivos. Un sistema de vetas mineralizadas en Ag-Pb-Zn post-datan el Skarn. El distrito de La Paz está dividido por dos sistemas de fallas muy bien defi nidas (N-S y E-W). La falla Dolores, de dirección N-S , muestra un desplazamiento normal vertical estimado entre 500 a 1000 m y separa la zona occidental de skarn de Au-Cu de la zona oriental que contiene al sistema hidrotermal de vetas de Ag-Pb-Zn. Esta falla se considera como parte del sistema de fallas Taxco-San Miguel de Allende. El fechamiento de los intrusivos mediante el método U-Pb en circones indica claramente un único evento de emplazamiento alrededor de 37 Ma. Esta fecha representa el último de los pulsos mineralizantes, posteriores a la orogenia Laramide,reconocido en el distrito de la Sierra de Catorce. Asimismo se reportan cuatro edades discordantes que sugieren la presencia de rocas greenvilianas en la base de una corteza gruesa (35–45 km). La geoquímica de los intrusivos muestra algunas diferencias en su composición, pero pertenecen a la serie magmática calco-alcalina con alto contenido de K. Los estudios de elementos mayores y traza muestran una evolución desde el campo adakítico hasta el campo de arco de islas, desde los intrusivos mineralizados a los estériles, respectivamente. Estos datos también sugieren la importancia del proceso de delaminación cortical y la necesidad de fallas profundas para transferir dicho magma y metales hacia la superficie.

3D KINEMATIC AND KINETIC ANALYSIS OF JAVELIN THROWING PERFORMANCE

Major studies on javelin throwing have focused more recently on kinematics studies, in two, and later, in three dimensions (3D), especially to analyse high performances (Bartlell & Best, 1988). However, there is a lack of literature reporting on kinetics data in javelin throwing event (Bartonietz, 2000). The main objective of this study is to develop a 3D kinematics and kinetics analysis of the final release phase of the javelin throw to explain javelin throwing performance

The N-end rule pathway is a sensor of heme

The conjugation of arginine, by arginyl-transferase, to N-terminal aspartate, glutamate or oxidized cysteine is a part of the N-end rule pathway of protein degradation. We report that arginyl-transferase of either the mouse or the yeast Saccharomyces cerevisiae is inhibited by hemin (Fe3+-heme). Furthermore, we show that hemin inhibits arginyl-transferase through a redox mechanism that involves the formation of disulfide between the enzyme's Cys-71 and Cys-72 residues. Remarkably, hemin also induces the proteasome-dependent degradation of arginyl-transferase in vivo, thus acting as both a "stoichiometric" and "catalytic" down-regulator of the N-end rule pathway. In addition, hemin was found to interact with the yeast and mouse E3 ubiquitin ligases of the N-end rule pathway. One of substrate-binding sites of the yeast N-end rule's ubiquitin ligase UBR1 targets CUP9, a transcriptional repressor. This site of UBR1 is autoinhibited but can be allosterically activated by peptides that bear destabilizing N-terminal residues and interact with two other substrate-binding sites of UBR1. We show that hemin does not directly occlude the substrate-binding sites of UBR1 but blocks the activation of its CUP9-binding site by dipeptides. The N-end rule pathway, a known sensor of short peptides, nitric oxide, and oxygen, is now a sensor of heme as well. One function of the N-end rule pathway may be to coordinate the activities of small effectors, both reacting to and controlling the redox dynamics of heme, oxygen, nitric oxide, thiols, and other compounds, in part through conditional degradation of specific transcription factors and G protein regulators

Survival after Lung Metastasectomy in Colorectal Cancer Patients with Previously Resected Liver Metastases

Background: Resection of hepatic metastases is indicated in selected stage IV colorectal cancer (CRC) patients. A minority will eventually develop pulmonary metastases and may undergo lung surgery with curative intent. The aims of the present study were to assess clinical outcome and identify parameters predicting survival after pulmonary metastasectomy in patients who underwent prior resection of hepatic CRC metastases. Methods: We performed a retrospective analysis of 27 consecutive patients (median age 62years; range: 33-75years) who underwent resection of pulmonary metastases after previous hepatic metastasectomy from CRC in two institutions from 1996 to 2009. All patients underwent complete resection (R0) for both colorectal and hepatic metastases. Results: Median follow-up was 32months (range: 3-69months) after resection of lung metastases and 65months (range: 19-146months) after resection of primary CRC. Three- and 5-year overall survival rates after lung surgery were 56 and 39%, respectively, and median survival was 46months (95% CI 35-57). Median disease-free survival after pulmonary metastasectomy was 13months (95% CI 5-21). At the time of last follow-up, seven patients (26%) had no evidence of recurrent disease and 6 of these 7 patients presented initially with a single lung metastasis. Conclusions: Resection of lung metastases from CRC patients may result in prolonged survival, even after previous hepatic metastasectomy. Yet, prolonged disease-free survival remains the exception, and seems to occur only in patients with a single lung lesio

Novel FixL homologues in Chlamydomonas reinhardtii bind heme and O2

AbstractGenome inspection revealed nine putative heme-binding, FixL-homologous proteins in Chlamydomonas reinhardtii. The heme-binding domains from two of these proteins, FXL1 and FXL5 were cloned, expressed in Escherichia coli, purified and characterized. The recombinant FXL1 and FXL5 domains stained positively for heme, while mutations in the putative ligand-binding histidine FXL1-H200S and FXL5-H200S resulted in loss of heme binding. The FXL1 and FXL5 [Fe(II), bound O2] had Soret absorption maxima around 415nm, and weaker absorptions at longer wavelengths, in concurrence with the literature. Ligand-binding measurements showed that FXL1 and FXL5 bind O2 with moderate affinity, 135 and 222μM, respectively. This suggests that Chlamydomonas may use the FXL proteins in O2-sensing mechanisms analogous to that reported in nitrogen-fixing bacteria to regulate gene expression

Diagnostic performance of fractional excretion of urea in the evaluation of critically ill patients with acute kidney injury: a multicenter cohort study

International audienceINTRODUCTION: Several factors, including diuretic use and sepsis, interfere with the fractional excretion of sodium, which is used to distinguish transient from persistent acute kidney injury (AKI). These factors do not affect the fractional excretion of urea (FeUrea). However, there are conflicting data on the diagnostic accuracy of FeUrea. METHODS: We conducted an observational, prospective, multicenter study at three ICUs in university hospitals. Unselected patients, except those with obstructive AKI, were admitted to the participating ICUs during a six-month period. Transient AKI was defined as AKI caused by renal hypoperfusion and reversal within three days. The results are reported as medians (interquartile ranges). RESULTS: A total of 203 patients were included. According to our definitions, 67 had no AKI, 54 had transient AKI and 82 had persistent AKI. FeUrea was 39% (28 to 40) in the no-AKI group, 41% (29 to 54) in the transient AKI group and 32% (22 to 51) in the persistent AKI group (P = 0.12). FeUrea was of little help in distinguishing transient AKI from persistent AKI, with the area under the receiver operating characteristic curve being 0.59 (95% confidence interval, 0.49 to 0.70; P = 0.06). Sensitivity was 63% and specificity was 54% with a cutoff of 35%. In the subgroup of patients receiving diuretics, the results were similar. CONCLUSIONS: FeUrea may be of little help in distinguishing transient AKI from persistent AKI in critically ill patients, including those receiving diuretic therapy. Additional studies are needed to evaluate alternative markers or strategies to differentiate transient from persistent AKI

Catalytically inactive human cathepsin D triggers fibroblast invasive growth

The aspartyl-protease cathepsin D (cath-D) is overexpressed and hypersecreted by epithelial breast cancer cells and stimulates their proliferation. As tumor epithelial–fibroblast cell interactions are important events in cancer progression, we investigated whether cath-D overexpression affects also fibroblast behavior. We demonstrate a requirement of cath-D for fibroblast invasive growth using a three-dimensional (3D) coculture assay with cancer cells secreting or not pro-cath-D. Ectopic expression of cath-D in cath-D–deficient fibroblasts stimulates 3D outgrowth that is associated with a significant increase in fibroblast proliferation, survival, motility, and invasive capacity, accompanied by activation of the ras–MAPK pathway. Interestingly, all these stimulatory effects on fibroblasts are independent of cath-D proteolytic activity. Finally, we show that pro-cath-D secreted by cancer cells is captured by fibroblasts and partially mimics effects of transfected cath-D. We conclude that cath-D is crucial for fibroblast invasive outgrowth and could act as a key paracrine communicator between cancer and stromal cells, independently of its catalytic activity

Three years of harvest with the vector vortex coronagraph in the thermal infrared

For several years, we have been developing vortex phase masks based on sub-wavelength gratings, known as Annular Groove Phase Masks. Etched onto diamond substrates, these AGPMs are currently designed to be used in the thermal infrared (ranging from 3 to 13 {\mu}m). Our AGPMs were first installed on VLT/NACO and VLT/VISIR in 2012, followed by LBT/LMIRCam in 2013 and Keck/NIRC2 in 2015. In this paper, we review the development, commissioning, on-sky performance, and early scientific results of these new coronagraphic modes and report on the lessons learned. We conclude with perspectives for future developments and applications.Comment: To appear in SPIE proceedings vol. 990