Synthesis of Carbonated Hydroxyapatite Nanorods in Liquid Crystals

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Syntheses of calcium phosphate nanoparticles, carried out in systems formed from surfactant, oil and water, have resulted in materials with promising possibilities for application. The calcium phosphate particles were synthesized using two different liquid crystals, formed from Renex (TM), cyclohexane and a salts solution. The morphology of the nanoparticles synthesized in the liquid crystals is similar to that of hydroxyapatite particles that form bone mineral, where collagen fibers connect these particles so as to form a composite. Therefore, the synthesis of calcium phosphate nanoparticles in the systems used in this work can advance current understanding of mineralization processes that result in the formation of bone mineral.123265268Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Temporal evolution of soot particles from C2H2/O-2 combustion in a closed chamber

An experimental study of soot formation in C2H2/O-2 flames at different C/O ratios in a closed chamber was carried out. The evolution temporal behavior and the volume fraction of soot particles were determined by laser extinction. It was found that total time for the soot formation phenomenon in flames from C2H2/O-2 with C/O ratio >0.75 or C2H2/O-2/Ar with C/O ratio = 1.00 was around 3.0-4.0 ms after ignition. At almost the same time the excited radicals reached their maximum emission intensity and the gases under combustion reached their maximum pressure. The micrographs show compact and approximately spherical soot particles with diameters within 60-150 nm. However, soot aggregates are not compact and they present a netlike structure similar to that of an aerogel.131475

CD98hc facilitates B cell proliferation and adaptive humoral immunity.

The proliferation of antigen-specific lymphocytes and resulting clonal expansion are essential for adaptive immunity. We report here that B cell-specific deletion of the heavy chain of CD98 (CD98hc) resulted in lower antibody responses due to total suppression of B cell proliferation and subsequent plasma cell formation. Deletion of CD98hc did not impair early B cell activation but did inhibit later activation of the mitogen-activated protein kinase Erk1/2 and downregulation of the cell cycle inhibitor p27. Reconstitution of CD98hc-deficient B cells with CD98hc mutants showed that the integrin-binding domain of CD98hc was required for B cell proliferation but that the amino acid-transport function of CD98hc was dispensable for this. Thus, CD98hc supports integrin-dependent rapid proliferation of B cells. We propose that the advantage of adaptive immunity favored the appearance of CD98hc in vertebrates

CD98 Increases Renal Epithelial Cell Proliferation by Activating MAPKs

CD98 heavy chain (CD98hc) is a multifunctional transmembrane spanning scaffolding protein whose extracellular domain binds with light chain amino acid transporters (Lats) to form the heterodimeric amino acid transporters (HATs). It also interacts with β1 and β3 integrins by its transmembrane and cytoplasmic domains. This interaction is proposed to be the mechanism whereby CD98 mediates cell survival and growth via currently undefined signaling pathways. In this study, we determined whether the critical function of CD98-dependent amino acid transport also plays a role in cell proliferation and defined the signaling pathways that mediate CD98-dependent proliferation of murine renal inner medullary collecting duct (IMCD) cells. We demonstrate that downregulating CD98hc expression resulted in IMCD cell death. Utilizing overexpression studies of CD98hc mutants that either lacked a cytoplasmic tail or were unable to bind to Lats we showed that CD98 increases serum-dependent cell proliferation by a mechanism that requires the CD98hc cytoplasmic tail. We further demonstrated that CD98-dependent amino acid transport increased renal tubular epithelial cell proliferation by a mechanism that does not require the CD98hc cytoplasmic tail. Both these mechanisms of increased renal tubular epithelial cell proliferation are mediated by Erk and p38 MAPK signaling. Although increased amino transport markedly activated mTor signaling, this pathway did not alter cell proliferation. Thus, these studies demonstrate that in IMCD cells, the cytoplasmic and extracellular domains of CD98hc regulate cell proliferation by distinct mechanisms that are mediated by common MAPK signaling pathways

New methodology based on static light scattering measurements for evaluation of inhibitors for in bulk CaCO3 crystallization

In the present work a new procedure for evaluation of scale inhibitor for calcium carbonate is proposed based on continuous measurement of particle size distribution by laser diffraction technique and simultaneous pH recording. From data obtained during real-time monitoring of the homogeneous nucleation and growth of CaCO3 particles formed in the bulk phase after the addition of carbonate ions to synthetic formation water (AF-W2), it was possible to evaluate the performance of four inhibitors classified in two groups: phosphonates (ethylenediamine tetramethylene phosphonic acid, EDTMP; diethylenetriamine pentamethylene phosphonic acid, DETPMP) and polymeric inhibitors (phosphino poly carboxylic acid, PPCA; polyvinyl sulfonate, PVS). The comparative bulk crystallization inhibition efficiency for the evaluated inhibitors, under the experimental conditions used in this work, increases in the following order: EDTMP < DETPMP < PVS congruent to PPCA. Moreover, this methodology allowed the deduction of the main mechanism of their inhibiting action: nucleation inhibition or crystal growth retardation. (c) 2014 Elsevier Inc. All rights reserved.4205764Petrobras-CENPESANP [0050.0049964.09.9]ANP [0050.0049964.09.9

Effect of hydrazine deproteination on bone mineral phase: A critical view

Over the last 30 years several techniques have been developed to separate bone matrix and bone mineral, in order to allow for a study of each component independently of the other. Preservation of original characteristics of the phase studied after isolation has always been a great challenge for all such techniques. The hydrazine deproteination procedure, first proposed by Termine, has been one of the processes most widely used for studying bone mineral. It is found to be one of the most effective, notwithstanding controversy over its efficiency in bone deproteination and criticism regarding possible changes it could make to the characteristics of bone mineral. In this work, we have studied the possible chemical and physical alterations caused by the hydrazine deproteination process to bone mineral from rats and to other materials of biological interest. Materials were characterized by scanning electron microscopy (SEM), thermo-gravimetric analysis (TGA), X-ray diffractometry (XRD), inductive coupled plasma-optical emission spectroscopy (ICP-OES), C-H-N analysis and infrared spectroscopy (FTIR), before and after hydrazine deproteination. Finally, here we present a comprehensive discussion on the criticism of hydrazine deproteination. The experimental results obtained in this work, even when compared to the results in the literature, show that most widespread criticism to the hydrazine deproteination process is not completely justified. (c) 2007 Elsevier Inc. All rights reserved.102113714

Quartz Crystal Microbalance Evaluation of Inhibitors for Inorganic Scale

In this paper, the use of a quartz crystal microbalance (QCM) with a quartz crystal sensor coated with iron oxide is proposed to evaluate the efficacy of inhibitors in the prevention of scale formation. The quartz crystal was first iron-plated by electrodeposition over the original gold film on the outer side of the crystal and then oxidized. The iron oxide layer is more representative for an evaluation of the inhibitor's effectiveness because tubing and equipment in oil-industry facilities are made of low carbon steel that is coated with an iron oxide layer. The scale formation was conducted under a steady supersaturation condition. The experiments were performed with slow addition (0.2 cm(3)/min) of 40 cm(3) of Na2CO3 solution (1,000 ppm) to 200 cm(3) of synthetic formation water (AF-W2). The performance at 10 ppm concentration of two commercial scale inhibitors, diethylenetriamine penta(methylenephosphonic acid) (DETPMPA) and polyphosphonocarboxylic acid (PPCA), was evaluated. The mass variation on the iron oxide plated QCM crystal sensor, caused by CaCO3 deposition, is related to supersaturation, pH value, and efficacy of scale inhibitor. Scanning-electron-microscope (SEM) images show that besides calcite crystals, there are also deposits in the form of spherical lenses, which is characteristic of the polymorph vaterite.183583588Petrobras-CENPES [0050.0049964.09.9]Petrobras-CENPES [0050.0049964.09.9

Studies of urea geometry by means of ab initio methods and computer simulations of liquids.

STUDIES OF UREA GEOMETRY BY MEANS OF AB INITIO METHODS AND COMPUTER SIMULATIONS OF LIQUIDS, A study was carried out on the urea geometries using ab initio calculation and Monte Carlo computational simulation of liquids. The ab initio calculated results showed that urea has a non-planar conformation in the gas phase in which the hydrogen atoms are out of the plane formed by the heavy atoms. Free energies associated to the rotation of the amino groups of urea in water were obtained using the Monte Carlo method in which the thermodynamic perturbation theory is implemented. The magnitude of the free energy obtained from this simulation did not permit us to conclude that urea is non-planar in water.25335836