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
Authors:E.T. Stepkowska, J. Perez-Rodriguez, M. Aviles, M. Jimenez de Haro, and M. Sayagues
Specific surface, S, of CSH-gel particles of disordered layered structure, was studied by water sorption/retention in two cement pastes differing
in strength, i.e. C-33 (weaker) and C-43 (stronger), w/c=0.4. Hydration time in liquid phase was th=1 and 6 months, followed by hydration in water vapour either on increasing stepwise the relative humidity, RH=0.5→0.95→1.0 (WS) or on its lowering in an inverse order (WR). Specific surface was estimated from evaporable (sorbed) water
content, EV (110C), assuming a bi- and three-molecular sorbed water layer at RH=0.5 or 0.95, respectively (WS). On WR it was three- and three- to four-molecular (50 to 75%), respectively, causing a hysteresis
of sorption isotherm. At RH=0.5 the S increased with cement strength from 146 m2 g-1 (C-33, 1 m) to 166 m2 g-1 (C-43, 1 m) and with hydration time to 163 (C-33, 6 m) and to 204 m2 g-1 (C-43, 6 m). At RH=1.0 (and 0.95), higher S-value were measured but these differences were smaller: S amounted to 190-200 m2 g-1 in C-33 (1 and 6 m) and 198-210 m2 g-1 in C-43 (1 and 6 m). Thus no collapse occurred on air drying of paste C-43 (6 m).
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:Ticiano do Nascimento, Irinaldo Basílio Júnior, Rui Macêdo, Elisana Moura, Camila Dornelas, Vanderson Bernardo, Vânia Rocha, and Csaba Nóvak
This article characterizes the stability of indinavir sulfate using different analytical techniques of quality control to
evaluate important steps in the manufacturing process of indinavir, specifically involving storage and compression. Indinavir
A, B, and C were obtained from different suppliers and submitted to DSC, Karl Fisher, NIR, XRPD analyses and dissolution assay.
DSC curves of indinavir presented endothermic peaks of fusion at 149–150 °C for indinavir A and B (form I) and 139–143 °C
for indinavir C (form II). When indinavir A and B were submitted to high Relative Humidity (RH) pseudo-polymorphic form II
was formed. Indinavir C converted into an amorphous substance when submitted to compression. Near infrared and Karl Fisher
assays detected high values of water for indinavir C in relation to indinavir A and B. X-ray powder diffraction of indinavir
B and C showed displacement of 0.05–0.10 θ in the peaks and higher angle of diffraction in relation to indinavir A. Amorphous indinavir C demonstrated a higher intrinsic
dissolution rate than indinavir A and B. Indinavir form I should be monitored during the pharmaceutical process to avoid its
conversion to indinavir form II or an amorphous substance which can alter the dissolution rate.
The chemical stability of a propellant and its influence on the ballistic properties during aging is a subject of interest.
The effect of aging on ballistic properties, viz., ignition delay, burning rate, and heat of combustion for an aluminised
ammonium perchlorate–hydroxyl-terminated polybutadiene (AP/HTPB) composite propellant during accelerated aging were investigated.
Samples of composite propellants were aged at 60 and 70 °C at relative humidity of 50% in a climatic chamber. The propellant
samples were tested with pressurized nitrogen gas environment for ignition delay measurement. Test results indicate that aging
does not have any appreciable effect on ignition delay. The change in ignition delay time is less than 3% within the scatter
of the data. Experiment results indicate that burn rate do affect with pressure but aging does not have much effect on burn
rate. It was also observed that the burning rate at low pressures did not undergo significant changes during the aging period.
The most significant of all the ballistic properties of this propellant is the burning rate exponent which increased by about
10% during the aging period.
The CISORP Water Sorption Analyser has been used to characterise a selection of solid samples at relative humidities from
0 to 100% and at ambient pressure. The analysis reveals many interesting features about the samples and shows the scope of
Hysteresis due to porosity and differences in the physical properties of similar chemical samples show up clearly in isotherm
curves. Kinetic curves reveal features such as the level of stability of dehydrated food products, changes in the hydration
states of salts, and the effect of adding powdered excipient on the water sorption behaviour of a pharmaceutical compound.
Kinetic curves were also used to compare the water sorption behaviour of two types of wood found inside a pine cone, and to
determine equilibrium moisture sorption by calculation.
It was shown that many samples take up moisture irreversibly under the experimental conditions such as amorphous sucrose and
other freeze-dried samples, as well as unstable crystalline forms of compounds. Wet samples such as soaked brick and archaeological
wood from a well dry out irreversibly even at 100% RH.
Recording isotherms at different temperatures allows the calculation of enthalpies of water sorption. If these are compared
with the enthalpy of water condensation the two processes can be compared quantitatively.
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.
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.
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