Authors:A. Ioannidou, E. Kotsopoulou, and C. Papastefanou
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.
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.
Authors:D. Giron, Ch. Goldbronn, M. Mutz, S. Pfeffer, Ph. Piechon, and Ph. Schwab
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.
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
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.
Authors:M. Marečić, F. Jović, V. Kosar, and V. Tomašić
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.
Authors:M. Pacenti, S. Dugheri, R. Gagliano-Candela, G. Strisciullo, E. Franchi, F. Degli Esposti, N. Perchiazzi, P. Boccalon, G. Arcangeli, and V. Cupelli
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.
Authors:M. Zoran, R. Savastru, D. Savastru, C. Chitaru, L. Baschir, and M. Tautan
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
. 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
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
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.
factors such as light, relativehumidity, 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
Authors:Esperanza Menéndez, Carmen Andrade, and Luis Vega
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 relativehumidity greater than 95%. After the initial curing, the test specimens were