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Abstract  

A method is proposed which, through the monitoring and modeling of the diurnal variation of α-radioactivity in the air near the ground, appears with a potential in enhancing the measurement of low radioactivity unexpected peaks over the natural background. Portable field instrumentation was used for the monitoring which further included the total γ-radiation at ground level, the relative humidity and temperature. The variation of the α-radioactivity follows a periodic form with peaks in the morning and in the afternoon. The applicability of a mathematical model to describe this variation of the α-radioactivity in terms of the meteorological variables and the γ-radiation was tested positive. This could reduce the difference between the measured and modeled periodic variation to an almost flat one, above which sudden unexpected peaks of radioactivity from possible undeclared nuclear activities could be easier identified.

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Abstract  

A new formulation of nifedipine tablets was prepared. The tablets were conditioned in amber-colored glass containers and placed in a climatized room at 40 °C and relative humidity of 75% for 180 days. Differential scanning calorimetry (DSC) and Thermogravimetry (TG) were used in order to evaluate the thermal properties of nifedipine, the excipients and two well-known nifedipine degradation products. There is no evidence of interaction between nifedipine and excipients or degradation products. High performance liquid chromatography (HPLC) was used in the dosage of nifedipine tablets before and after acclimatized exposure. Results show that DSC and TG offer important data for a more detailed assessment of the stability of a pharmaceutical formulation.

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Abstract  

The isothermal heat of hydration of MgSO4 hydrates was studied by humidity controlled calorimetry. Two hydrates, starkeyite (MgSO4·4H2O) and a mixture of MgSO4 hydrates with summary 1.3 mol H2O were investigated. The solid-gas reactions were initiated at 30°C and 85% relative humidity. The heat of hydration was determined in a circulation cell in the calorimeter C80 (Setaram). The crystal phases formed after the hydration process were analyzed by thermogravimetry (TG) and X-ray powder diffraction (XRD). Starkeyite reacted with the water vapour to the thermodynamic stable epsomite and the MgSO4 hydrate mixture with 1.3 mol water to hexahydrite. The hydration heats of starkeyite and the mixture were determined to be −169±3 and −257±5 kJmol−1, respectively.

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It is believed that lipids are the most important factor affecting nuts shelf-life. In the present study, an accelerated shelf-life testing by means of elevated temperatures 62, 72, and 82 °C was conducted to predict the oxidation stability of walnuts over a long-term storage. Peroxide value (PV) was employed to monitor the lipid oxidation progression in the walnuts. A range of 74.01–79.57 kJ mol−1 K−1 energy was required for formation of primary oxidation products. The reaction changes followed an apparent first-order kinetic. Formation of hydroperoxides in walnut kernels was found to be a temperature-dependent reaction with Q10 of 2.1. Walnut kernels were also kept in normal condition (temp: 20–30 °C; relative humidity (RH): 35–45%) for 12 months to validate the shelf-life estimation approach. The results showed that PV could provide a proper estimation for oxidative stability of the walnuts stored in ordinary condition.

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Abstract  

Airborne concentration levels of222Rn and its progeny, and220Rn progeny were measured in an underground U mine. In addition, concurrent measurements of several meteorological variables such as temperature, relative humidity, barometric pressure and airflow rate were also carried out. Mining operations and mining activities during the measurements were carefully noted. The data collected show great variability. Although not particularly strong, some definite correlations could be found between airborne radioactivity concentration levels, meteorological variables, and mining operations (and mining activities). The difficulty in obtaining stronger correlations between the above variables is attributed to the great and simultaneous variability of most of the variables measured. The data presented here are typical of active U–Th mining environments, i.e., of Ontario (Canada) underground U mines. Measurements extended for a period of a full calendar year and involved several thousand independent measurements.

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Abstract  

Knowledge of the dynamics of HTO in leafy plant–soil system is required to verify models, such as the NORMTRI code, which predict environmental tritium following its release. Tritium concentrations in plants has been evaluated using the code NORMTRI and experimentally by collection of samples of different plants and their soils samples. In the present study, major seasonal crop plants i.e. wheat, mustard, sugar cane, coriander, spinach, potato, were collected beyond Narora Atomic Power Station site boundary and gular, arandi, neem, ashok, amaltas, csuarina leaf samples within NAPS site boundary for analysis of HTO content. Data analysis indicated that HTO in leaf is strongly influenced by atmospheric relative humidity and type of the plant.

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Journal of Thermal Analysis and Calorimetry
Authors: M. Odlyha, Q. Wang, G. M. Foster, J. de Groot, M. Horton, and L. Bozec

Summary  

Dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and thermogravimetry (TG) have been used to characterise model tapestries, especially woven for the EC-funded project (MODHT) and to historic tapestries in royal palaces and museums. Modulus values of woollen threads from model tapestries are reported and the effects of traditional dyeing and mordanting processes quantified. TG, particularly of black woollen threads showed alterations in thermal stability. Tests of creep on immersion in water and subsequent heating to 90C and on exposure to a controlled relative humidity programme were also used to rank these effects. Modulus values of historic woollen samples were also obtained and DSC studies of model and historic silk samples are reported together with preliminary atomic force microscopy (AFM) images of silk fibres.

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An impact of temperature, light and relative humidity were studied on root colonisation by mycorrhizal fungi and on pine seedling growth. Moderate and high light intensities favoured mycorrhizal colonisation and seedling growth. Pine seedlings inoculated with Pisolithus tinctorius compared to other fungi attained maximum growth. Survival of pine seedlings was higher under moderate light intensity than low and high light intensity. Seedling growth and mycorrhizal colonisation was better at 25°C than 10°C. Variation in humidity did not show much difference in mycorrhizal colonisation and seedling growth. However, seedling survival was greater at high than at low humidity. Pine seedlings showed best survival with 0.5 P level (46.153 mg P/kg soil) of phosphorus at 25 °C temperature and under moderate light intensity. Among the mycorrhizal fungi used P. tinctorius was the most effective endophyte and was followed by Laccaria laccata, Rhizopogon luteolus and Collybia radicata under various physical factors.

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The aim of the paper is to determine a methodology for calculating the needed airflow rate (including fresh air) in an occupied room, based on carbon dioxide measurement and calculation, in order to maintain the comfort indoor air quality. The calculated airflow rate should optimize the investment and the operating costs of HVAC equipment. In the work there are analyzed the calculation methods used to determine the ventilation airflow rate. It is presented the methodology for calculating the ventilation airflow rate for a room with people inside by using the measured values of carbon dioxide concentration. The connection between carbon dioxide concentration and ventilation airflow rate is verified by experimental measurements. This methodology is applicable in Slovakia because it complies with all current standards. The result obtained by using this calculation method is almost the same with that achieved from experimental measurements. To confirm the results, it is presented a case study of an office with occupants, in which the ventilation airflow rate calculation method is applied.In the article only a part from the total work is presented. The experimental measurements were carried out from 2011 to 2014. Approximately 54 measurements were covering total days or weeks. The following factors have been measured: indoor air temperature, outdoor air temperature, relative humidity of indoor air, relative humidity of outdoor air, concentration of CO2 in indoor air, concentration of CO2 in outdoor air, pressure difference and wind velocity. Ventilation by infiltration was calculated based on these factors using several methodologies. The methodology of measurement is not subject to the article. In this article only one aspect is investigated: CO2 concentration.

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Abstract  

The stability of Supersulphated Cement (SSC) is investigated at 95°C when subjected to relative humidities of 100, 53 and 11% of water vapour. Previously [1] investigations at 25, 50, 75°C under the same conditions of humidity reported the stability of ettringite, one of the initial hydration products. At 95°C, decomposition of ettringite, is found at all humidities and is rapid at 100% relative humidity. The hydration products of cement pastes at a water cement ratio of 0.27 were determined by thermogravimetry (TG) and X-ray diffraction (XRD). The formation of the hydragarnet, plazolite is recorded during the decomposition/dehydration process enhanced by possible carbonation. Rehydration studies on the products after storage for up to 9 months were carried out using distilled water and the samples tested for ettringite content. It is concluded that ettringite in SSC is inherently unstable at 95°C.

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