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Abstract  

7Be activity concentrations were measured in the lower atmosphere at Thessaloniki, Northern Greece (40°38′N, 22°58′E) over the year 2009, a year of a particular minimum of solar activity. The mean annual activity concentration of 7Be at that year was 6.01 mBq m−3. The variability of 7Be surface concentrations related to the solar cycle appeared to be deviated about 40% between the maximum and the minimum values. A positive correlation (R = 0.97) was revealed between the activity concentrations of 7Be and the temperature, confirming that the increased rates of vertical transport within the troposphere, especially during the warmer months, resulted in carrying down to the surface layer air masses enriched in 7Be. Relatively high values of 7Be activity concentrations were observed by increasing of the tropopause height. A negative correlation (R = −0.65) between the 7Be activity concentrations and the relative humidity was due to the condensation process in the lower atmosphere which resulted in increased aerosol particle sizes with higher scavenging rates of aerosols and low activity concentrations of 7Be in the atmosphere. Influence of precipitation on the changes of 7Be activity concentrations was also observed.

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Abstract  

The interaction between samples of metallic zinc and water vapour was studied gravimetrically, both in the absence and in the presence of oxygen. The experimental total mass gain vs. time curves exhibited two plateaus, whose heights increased with, elevations both of relative humidity and of temperature. The amount of product retained on the surface after desorption was also determined as a function of time. The product was identified as hydrated zinc oxide. In the runs conducted without oxygen, the retained product curves displayed a time delay with respect to the total mass gain curves. In the presence of oxygen, however, there was practically only one chronogravimetric curve. This behaviour is interpreted on the basis of a common mechanism involving the formation of an intermediate precursor oxide, which is more readily formed in the presence of oxygen than in its absence. A set of mathematical equations was derived, from which the rate constants for both processes were obtained. The second step was ascribed to a further weak adsorption of water.

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Journal of Thermal Analysis and Calorimetry
Authors: D. Giron, Ch. Goldbronn, M. Mutz, S. Pfeffer, Ph. Piechon, and Ph. Schwab

Abstract  

Manufacturing processes may involve the presence of water in the crystallization of the drug substance or in manufacturing or in the composition of the drug product through excipients. Dehydration steps may occur in drying, milling, mixing and tabletting processes. Furthermore, drug substances and drug products are submitted to different temperatures and relative humidities, due to various climatic conditions giving rise to unexpected hydration or dehydration aging phenomena. Therefore the manufacture and the characterization of hydrates is part of the study of the physical properties of drug substances. Several hydrates and even polymorphic forms thereof can be encountered. Upon dehydration crystal hydrates may retain more or less their original crystal structure, they can lose crystallinity and give anamorphous phase, they can transform to crystalline less hydrated forms or to crystalline anhydrous forms. The proper understanding of the complex polyphasic systemhydrates–polymorphs–amorphous state needs several analytical methods. The use of techniques such as DSC-TG, TG-MS, sorption-desorption isotherms, sub-ambient experiments, X-ray diffraction combined with temperature or moisture changes as well as crystal structure and crystal modelling in addition to solubilities and dissolution experiments make interpretation and quantitation easier as demonstrated with some typical examples.

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Abstract  

MDF cements using the blends of sulfoaluminate ferrite belite (SAFB) clinkers and ordinary Portland cement (OPC) in mass ratio 85:15 with Al2O3, and starch, polyphosphate (poly-P) or butylacrylate/acrylonitrile were subjected to moist atmospheres (ambient, 52 and 100% relative humidity (RH)) to investigate their moisture resistance. Their chemical, thermal, electron microscopic and magnetic properties were also studied before and after moisture attack. Butylacrylate/acrylonitrile (BA/AN) copolymer was found to be the most suitable for MDF cement synthesis since the sample containing BA/AN showed the best moisture resistant. There are significant differences in scanning electron microscopy (SEM) of MDF cements before and after moisture attack and with different polymers. New data on the paramagnetic nonhysteresis magnetization curves for all the samples are observed. The MDF cements synthesized from SAFB clinker with dissolved poly-P give the best signal/noise (S/N) ratio. Three main temperature regions on TG curves of both series of MDF cements are observed. In the inter-phase section of MDF cements, the content of classical cement hydrates decomposing by 250C is increased. Combustion of organic material took place by 550C. In the temperature range 550-800C, the decomposition of CaCO3 occurs.

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Abstract  

The system of sulfoaluminate ferrite belite (SAFB) clinkers premixed with Portland cement (PC) in mass ratio 85:15 in combination with hydroxypropylmethyl cellulose (HPMC) or polyphosphates(poly-P) was used for the syntheses of Macro-Defect-Free (MDF) materials. The subsequent moisture treatment and thermal stability of these MDF materials were investigated. The effect of individual humidity upon the evolution of mass is more intensive than the effects of composition of MDF materials or duration of the original MDF material synthesis. Detailed values of mass changes at 100% relative humidity (RH) and under ambient conditions are strongly affected by the nature of polymer used. A significant improvement of moisture resistance of MDF materials is achieved when the materials are dried after 24 h of finishing the pressure application. In the inter-phase section of MDF material samples, the content ofC-(A,F)-S hydraulic phases, mainly tetracalcium aluminate ferrite monosulphatehydrate (AFm) decomposing by 250°C and CaCO3 decomposing at 600–700°C increase after the moisture attack, while cross-links in AFm-like section with typical thermoanalytical traces in temperature region 250–550°C remain intact.

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Abstract

This work deals with the photocatalytic oxidation of toluene at room temperature and atmospheric pressure in the gas phase. The differential equations of the reactor model are solved numerically with simultaneous estimation of the model parameters. Estimation of the kinetic data is performed using a modified differential method of data analysis and a Nelder–Mead method of nonlinear optimization for parameter estimation. The reaction is performed in an annular photoreactor using UVA black light blue fluorescent lamp. The experiments are carried out at different total flow rates of the reaction feed (20–160 cm3 min−1), two different inlet concentrations of toluene (2.67 and 5.24 g m−3) and at constant relative humidity (25%). A good agreement between the experimental data and theoretical predictions is obtained, supporting the applicability of the proposed models to describe the investigated process performed in laboratory annular photoreactor.

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Abstract  

South-Eastern part of Romania has a highest potential seismic risk in Europe due to the earthquake-prone Vrancea zone placed at conjunction of four tectonic blocks in the South-Eastern part of Carpathian Arc. This paper is an attempt to analyze the development of radon pre-earthquake anomaly in relation with moderate seismic events in Vrancea area through permanent monitoring with solid state nuclear track detectors CR-39 detectors. Radon in air above the ground was measured during 1 year period (November 2010–October 2011) in four selected test sites: Vrancioaia (VRI) and Plostina (PLOR) located in Vrancea zone, and Muntele Rosu-Cheia and Bucharest. During sampling period recorded earthquakes that occurred mostly in Vrancea epicentral region were minor-moderate of moment magnitudes in range of
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. The average radon concentration in air above the ground measured with CR-39 detectors and 10 days period recorded simultaneously at all test sites, registered the following values: (1) in Vrancea area (similar in VRI and PLOR) was 1094.58 
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 150.3 Bq/m3; (2) at Muntele Rosu-Cheia seismic station measured in a mountain tunnel laboratory was 3695.91 ± 440 Bq/m3; (3) at Bucharest station was 380.53 
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 69.17 Bq/m3, and 10 days CRn fluctuations in the range of (88 
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 40 to 912
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 130 Bq/m3). Clear radon anomalies, mostly at VRI and PLOR in Vrancea epicentral area as well as at Muntele Rosu-Cheia have been measured before seven minor earthquakes which were recorded in the range of moment magnitude
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$4 \le M_{w} \le 4.9$$ \end{document}
in Vrancea area. Temporal variation of radon in air near the ground have been examined in relation with meteorological parameters like as air temperature, relative humidity, air pressure and wind velocity. Permanent monitoring of radon concentration anomalies in seismic area Vrancea is an important issue as surveillance tool in the field of earthquake hazard for Romania.
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Acta Chromatographica
Authors: M. Pacenti, S. Dugheri, R. Gagliano-Candela, G. Strisciullo, E. Franchi, F. Degli Esposti, N. Perchiazzi, P. Boccalon, G. Arcangeli, and V. Cupelli

Summary

2-Chloroacetophenone (CA) is widely used as tear gas by law-enforcement agents, and by civilians for personal protection. Crimes involving robbery and rape using tear gas sprays have recently increased. Experimental and in-field evaluations have been performed to validate use of solid-phase microextraction (SPME) with a porous fiber for sampling and analysis of CA in air before analysis by fast gas chromatography-mass spectrometry equipped with a new device called a multi-fiber system. CA vapor was generated by use of a syringe pump in a dynamic system in which temperature, relative humidity, and air velocity were monitored. The theoretical sampling rate for time-weighted average and rapid-SPME were, furthermore, estimated by use of the Fuller-Schettler-Giddings diffusion coefficient and the theory of heat transfer, respectively, and were in accordance with experimental values. Concentrations of CA were analyzed in a military store containing tear gas canisters, to evaluate the risk. The results obtained in this field study showed values ranging from 0.206 to 2.46 mg m−3.

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factors such as light, relative humidity, and pollutants on objects both in outdoor and indoor environments are studied in preventive conservation. To achieve this, monitoring is performed of the microclimate surrounding the object using both diffusive

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.03 Paste cubes were manufactured with a water/cement ratio equal to 0.5 and with dimensions of 3.5 cm 3 . They were cured for 24 h in a humidity chamber at 20 °C with a relative humidity greater than 95%. After the initial curing, the test specimens were

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