Ceramic properties of kaolinitic clay with monoaluminum phosphate (Al(H2PO4)3) addition

Journal of Thermal Analysis and Calorimetry - The effect of monoaluminum phosphate (Al(H2PO4)3) addition in the thermochemical process of a kaolinitic clay was studied and compared with the pure...     

Cigarette smoke extract induced protein phosphorylation changes in human microvascular endothelial cells in vitro

Phosphorylation is the most widely studied posttranslational modification (PTM) and is an important regulatory mechanism used during cellular responses to external stimuli. The kinases and phosphatases that regulate protein phosphorylation are known to be affected in many human diseases. Cigarette smoking causes cardiovascular disease (CVD). Endothelial cells play a pivotal role in CVD initiation and development; however, there have been limited investigations of the specific signaling cascades and protein phosphorylations activated by cigarette smoke in endothelial cells. The purpose of this research was to better understand the differential protein phosphorylation in endothelial cells stimulated with extracts of cigarette smoke total particulate matter (CS-TPM) in vitro. Human microvascular endothelial cells were exposed in vitro to CS-TPM at concentrations that were shown to cause endothelial cell dysfunction. The phosphorylated proteins were isolated using phosphoprotein-specific chromatography, followed by enzymatic digestion and nano-flow capillary liquid chromatography (ncap-LC) coupled to high resolution mass spectrometry. This study putatively identified 94 proteins in human microvascular endothelial cells that were differentially bound to a phosphoprotein-specific chromatography column following exposure to CS-TPM suggesting differential phosphorylation. Pathway analysis has also been conducted and confirmations of several observations have been made using immunoaffinity-based techniques (e.g., Western blotting). Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Investigating the temporal variation of the scaling behavior in rainfall data measured in central Argentina by means of detrended fluctuation analysis

Investigation of the time variant scaling behavior of six monthly rainfall series recorded in central Argentina from 1860 to 2006 by using detrending fluctuation analysis (DFA) was performed. Changes in precipitation extremes are analyzed for several regions of Argentina using long-term monthly rainfall data (back to 1860) recorded by rain gauges extended for more than 10 latitude-degrees, from subtropical regions until 39^° S. A moving window was employed in order to analyze statistical changes. Three different types of time patterns can be distinguished: (i) eastern stations show visible crossovers between persistent and random behavior; (ii) north-western stations are characterized by random behavior approximately at any time and do not present visible crossovers between different types of scaling behaviors; (iii) one station (i.e. Corrientes) shows a peculiar pattern, since it is characterized by several crossovers from persistent to random behavior, indicating a more fluctuating time dynamics without a well defined trend. The obtained results can be interpreted in the context of the climatological conditions of Central Argentina, which is characterized by the continental heat low in the northwest region, by the subtropical rainforest in the eastern provinces and by a transition zone (from maritime to continental regime) fluctuating with the South Atlantic high-pressure cell.     

Thermal analysis to assess pozzolanic activity of calcined kaolinitic clays

The use of calcined clays as partial replacement of cement is encouraged since it promotes the reduction of the green-house gas emission and the energy requirement of cement-based material, maintaining or enhancing the mechanical properties and the durable performance of these materials. In this paper, the use of thermal methods—DTA/TG and calorimetry—to select and to evaluate two kaolinitic clays for their use as pozzolanic materials was explored. The content and crystallinity of kaolinite in clays can be determined by DTA/TG analysis, and this technique is also suitable to select the calcination temperature for complete kaolinite dehydroxylation. Calorimetric analysis on blended cements (30 % by mass of replacement) can differentiate the reactivity of calcined kaolinitic clays. Results show that more reactive calcined kaolinitic clay develops the second and third peaks earlier than those of PC with great intensity and high acceleration. The reactivity of calcined clays is associated to raw materials containing kaolinite with high structural disorder that determines calcined clays with large specific surface area, high grindability, and small mean particles size (d ₅₀) for the same grinding objective. Finally, the DTA/TG analysis can determine the type and the amount of hydrated phases obtained at different ages to evaluate the pozzolanic reaction of calcined clay in accordance with the standardized pozzolanic activity index.     

β-Sheet 13C structuring shifts appear only at the H-bonded sites of hairpins

The (13)C chemical shifts measured for designed β-hairpins indicate that the structuring shifts (upfield for Cα and C', downfield for Cβ) previously reported as diagnostic for β-structuring in proteins appear only at the H-bonded strand residues. The resulting periodicity of structuring shift magnitudes is not, however, a consequence of H-bonding status; rather, it reflects a previously unrecognized alternation in the backbone torsion angles of β-strands. This feature of hairpins is also likely to be present in proteins. The study provides reference values for the expectation shifts for (13)C sites in β-structures that should prove useful in the characterization of the folding equilibria of β-sheet models.     

Characterization of polycyclic aromatic hydrocarbons and carbonyl compounds in diesel exhaust emissions

Exhaust emissions from a recent model heavy-duty diesel vehicle (city bus) in a chassis dynamometer were measured during a transient driving cycle. Particle-bound polycyclic aromatic hydrocarbons (PAHs) and gaseous carbonyls, substances that create health hazards and are, as yet, unregulated were collected, the former on filters and the latter on dinitrophenylhydrazine (DNPH)-coated silica cartridges and analysed by GC-MS and HPLC, respectively. PAH emission rates decreased with the number of benzene fused rings. They averaged 0.2 mg km(-1) for a total of 11 PAHs ranging from fluoranthene to benzo(ghi)perylene. Fluoranthene and pyrene accounted for 90% of total PAHs. The sum of emission rates of C1 approximately C6 carbonyls averaged 174 mg km(-1), even if formaldehyde alone represented approximately 70% of the total carbonyl mass, followed by acetaldehyde (13%). Results obtained were compared with emission data reported in previous studies.