Radon mitigation using an air cleaner

Room experiments were conducted to investigate the effects of an air cleaner on radon mitigation. Radon concentration, equilibrium equivalent radon concentration and unattached fraction were measured during the experiments. Two types of filtration were tested using the air cleaner which has a high efficiency particulate air filter (HEPA-filter) and a deodorizing activated carbon (carbon-filter). One is the filtration with the HEPA-filter plus carbon-filter and the other is the filtration with only the HEPA-filter. The effective doses from radon progeny were significantly decreased. Both filtration methods were effective for the mitigation of effective dose due to radon progeny.     

Air oxidation of organic compounds in aqueous solutions. Ecochemical and analytical aspects

The results of static and dynamic laboratory experiments confirm the oxidation of organic compounds in aquatic medium by dissolved oxygen of atmospheric air to be possible under conditions close to normal. Alkylaromatics containing hydrogen atoms in alkyl substituents in α-positions to the aromatic system, as well as simple ethers, are characterised by the highest chemical reactivity in relation to triplet (³Σ _g ^? ) which is consistent with the pattern of free-radical reactions. Principal environmental and analytical consequences of the obtained results are under discussion. Liquid-phase free-radical reactions of atmospheric oxygen may proceed with the participation of atmospheric aerosols, i.e water droplets within clouds. Another example relates to the prevention of accumulation in natural bodies of water stable nonylphenol (predominantly 4-tert-isomers), characterized by endocrine activity. Suggested the possibility of replacing them with secondary alkylphenols, identical in all chemical properties except for the ease of oxidation by air oxygen in aqueous solutions     

Charging processes of particles produced from dilute xylene in air under electron beam irradiation

The yields of charged particles relative to those of total particles from o-xylene based on their number and volume concentrations (η_N and η_V) and the polarities of the charged particles of products were examined under EB irradiation without and with external fields applied to irradiated air mixtures, which are the conditions with bipolar ions and unipolar ions, respectively. The η_N and η_V by bipolar ions were constant at 31–37% and 56–59%, respectively, independent of dose and initial xylene concentration, while those by unipolar ions were 48–55% and 91–93%, respectively.     

Brønsted acid ionic liquid [Et3NH][HSO4] as an efficient and reusable catalyst for the synthesis of 2,4,5-triaryl-1H-imidazoles

A simple and efficient procedure for synthesis of 2,4,5-triaryl-1H-imidazoles by one-pot three-component condensation of aromatic aldehydes, benzil and ammonium acetate under solvent-free conditions using ionic liquid [Et₃NH][HSO₄] as catalyst is described. The remarkable features of this procedure are high yields, cleaner reaction profiles, use of non-toxic, easily available, cheap, recyclable catalyst, which also has an environmentally benign nature, and simple experimental and work-up procedures.     

An efficient and reusable heterogeneous catalyst Animal Bone Meal for facile synthesis of benzimidazoles, benzoxazoles, and benzothiazoles

A library of benzimidazoles, benzoxazoles, and benzothiazoles was efficiently synthesized by condensation of o-phenylenediamine, o-aminophenol, and o-aminothiophenol respectively with aromatic aldehydes in the presence of catalytic amounts of Animal Bone Meal (ABM) and Lewis acids doped ABMs. Reactions were conducted under reflux conditions in air. The remarkable features of this new protocol are high conversion, short reaction times, and cleaner reaction profiles, straightforward procedure, and reduction in catalyst toxicity.     

Simultaneous chromatographic identification of a few components in mixtures based on a correlation between their absolute or relative retention times under different conditions

A correlation was established between the absolute and relative retention parameters of various compounds under different conditions of chromatographic analysis (isothermal and temperature programming conditions in gas chromatography or isocratic and gradient elution in high-performance liquid chromatography). This correlation is described by the linear regression equations t _R (II) = = at _R (I) + b with a high degree of accuracy. This property of chromatographic retention parameters allowed us not only to recalculate the values of these parameters determined under different conditions, but also to propose an algorithm for the simultaneous identification of a few components in complex mixtures with the use of published data on retention parameters found under other conditions (even presented as the drawings of chromatograms).     

Radiation-induced gaseous admixture oxidation in the droplet phase

The theoretical estimations of the possibility of gaseous admixture removal processes by radiation-induced chemical reactions in water aerosols were made. The ranges of droplet size (R) and dose rate in liquid phase (I) for admixture removal in kinetic regime were estimated. The experiments for SO₂ and NO removal by E-beam irradiation of air with aerosol droplets in a one-pass flow system have been carried out (P=1 atm, T=285–340 K). The dependencies of the impurities removal efficiencies on aerosol volume fraction (L), T and dose rates have been obtained. At R=10–100 μm, L⩾10^-4, I⩽10 kGy s^-1 the extreme removal rates for SO₂≈10³ ppm s^-1 and for NO=100–200 ppm s^-1 were achieved. For initial SO₂ content ≅1000 ppm and NO≅300 ppm the removal efficiency of 90–95% was achieved at dose 5–10 kGy and L=2−3×10^-4.     

Atmospheric levels and distribution of Dechlorane Plus in an E-waste dismantling region of East China

Atmospheric concentrations of Dechlorane Plus(DP)were investigated in Taizhou,an electronic-waste(E-waste)dismantling region in East China.Passive air samplers with polyurethane foam(PUF)disks were deployed every three months during the sampling period of September 2009-August 2010.The total DP(syn-and anti-DP)concentrations in air ranged from not detected to 277 pg/m~3,with a mean concentration of 53.9 pg/m~3.A generally declining trend of DP levels was found from the E-waste dismantling region to the peripheral areas.The median values of total DP concentrations in autumn,winter,spring and summer were 52.2,28.8,39.7 and 30.1 pg/m~3,respectively.The seasonal variations of DP concentrations were mainly associated with the intensity of E-waste dismantling activities and meteorological conditions.The mean value of anti-DP fractional abundance(f_(anti))was 0.74±0.08,which was consistent with those in the commercial DP products.This study confirmed a significant emission source related to the distribution of atmospheric DP in the E-waste dismantling area and supplied information for the seasonal variation of DP in the atmosphere.     

Calorimetric and thermoanalytical assessment of mechanically activated PbCO3

Excess enthalpy values, ΔH*, were obtained through the change in the heats of dissolution into Na—EDTA (ΔH*_L) as well as of decomposition to PbO (ΔH*_D). They tallied fairly well with each other, although a slight systematic discrepancy depending on the conditions of vibro-milling was recognized. A good correlation between ΔH* and the relative non-crystallinity was observed when the material was activated under the same conditions with a varying grinding time. Changes in the grinding conditions, such as in amplitude or atmosphere, brought about a considerable shift of the correlation between ΔH* and the non-crystallinity. Thus, under the same degree of non-crystallinity, materials ground in cyclohexane stored a larger amount of energy than those ground in air. These differences in the correlation were discussed by referring the degree of dispersion, the distribution of active sites, and the effect of temperature.     

Expeditious and Efficient Synthesis of Benzoxazoles,Benzothiazoles, Benzimidazoles Catalyzed by Ga(OTf)3 under Solvent‐Free Conditions

A new and efficient method for the synthesis of benzoxazoles, benzothiazoles, benzimidazoles from reactions of o‐substituted aminoaromatics with orthoesters in the presence of catalytic amounts of Ga(OTf)₃ under solvent‐free conditions is presented. The remarkable features of this new protocol are high conversion, very short reaction times, cleaner reaction profiles under solvent‐free conditions, straight forward procedure, and use of relatively non‐toxic catalysts.     

Stepwise injection photometric determination of nickel in air aerosols

A procedure is developed for the automated determination of nickel in air aerosols; it involves the adhesive separation of aerosols on a fiberglass column in the on-site mode followed by the photometric determination of analytes with dimethyl glyoxime under the conditions of stepwise injection analysis of aerosol concentrates. The analytical range for nickel is 1.5–38 μg/m³; the detection limit of the method is 0.5 μg/m³ at an air sample volume of 30 L. The duration of sampling to an adhesive column and concentrate analysis were 15 and 10 min, respectively.     

Radiolysis of pyridoxine (vitamin B6) in aqueous solution under different conditions

Aqueous solutions of pyridoxine (1 mM) without or with additive of K₃[Fe(CN)₆] (2.5 mM) were gamma-irradiated at different doses and dose rate of 2.16 kGy/h in the absence of air, in the presence of air or by their saturation with N₂O. The radiolytic products were analyzed with HPLC, mass spectrometry and UV spectroscopy. 2,4,5-Trihydroxymethyl-3-pyridinol, pyridoxal, isopyridoxal and 6-hydroxypyridoxine were formed by radiolysis in the absence of K₃[Fe(CN)₆], and their concentrations were much higher in samples saturated with N₂O. Pyridoxi-3,6-quinone was found by radiolysis under all the above-mentioned conditions but only in the presence of K₃[Fe(CN)₆]. Besides, the pyridoxal formation increased in the presence of this oxidizing agent. G values of pyridoxal formation and pyridoxine degradation were quantified. Some details of the radiolytic product formation were discussed.     

Simple method of evaluating absorbed dose in electron-beam processing

The use of semiempirical multilayer depth-dose code EDMULT for evaluating the absorbed- dose coefficient K was studied with a personal computer. When multiplied by the charge per unit area, the coefficient gives the adsorbed dose in the sample irradiated by electrons. This relation presupposes the model configuration of the plane-parallel beam normally incident on the four-layer slab absorber. The absorber consists of the accelerator window, the air layer, the sample and the substratum. The initial energies of electrons above 100 keV were considered. The values of K obtained agreed reasonbly well with the values in the literature. The absorbed doses estimated from K were compared with the values measured by the radiochromic dosimeter for various sets of irradiation conditions. The r.m.s. deviation of the former from the latter was 6.7%. A calculated example of the effects of different substratum materials is given.     

Evaluation of airborne particles at the Alhambra monument in Granada, Spain

As a part of an ongoing investigation regarding the air quality at the Alhambra monument (UNESCO World Cultural Heritage), indoor and outdoor atmospheric aerosols (PM₁ and PM_10-1) and pollutant gases (O₃, NO₂, SO₂ and NH₃) were studied during summer and winter. Bulk elements, ionic compounds and black carbon (BC) in aerosols were analyzed with X-ray fluorescence spectrometry, ion chromatography and aethalometry/reflectometry, respectively. Natural PM_10-1 aerosols, such as carbonate-rich soil and sea salts, reacted with a typical urban atmosphere, producing a mixture of particulates with diverse chemical composition. The content/formation of secondary inorganic aerosols depended on the air temperature and absolute humidity. Ratios of typical mineral elements (i.e., Ti/Fe and Si/Fe) showed that Saharan dust events contribute to the composition of the observed mineral aerosol content. BC, V and Ni originated from diesel exhaust, while Cu, Cr, Pb and Zn came mainly from non-exhaust vehicular emissions. Weathering phenomena, such as blackening and pigment discoloration, which could arise from gradual aerosol deposition indoors, are discussed.     

Oxygen Transfer in Solid-State Cultivation Under Controlled Moisture Conditions

The aim of this work was to study oxygen transfer as a function of the initial moisture content in solid-state cultivation under controlled moisture conditions. The use of controlled moisture conditions prevents drastic changes in the medium during cultivation, allowing the use of a pseudo-steady-state model to estimate the overall oxygen mass transfer coefficient (K _L a) in the biofilm around the solid particles. Drechslera (Helminthosporium) monoceras, an aerobic mold that produces allergenic proteins, was cultured on wheat bran in a packed bed column bioreactor. The bed height (30 mm) and air flow rate (0.4 L/min) were selected to implement moisture control. The results show that there is an optimal moisture content (35 %) at which a lower biofilm thickness and packing of the bed improves K _L a. However, a higher biomass growth was obtained at 45 % moisture. The different patterns of biomass growth demonstrate the importance of the balance between aerial and film growth in solid-state cultivation. These results contribute to the understanding of oxygen transfer in solid fermentation, optimization of processes, and production of allergen extracts from D. (Helminthosporium) monoceras biomass.     

Effects of Inoculum Physiological Stage on the Growth Characteristics of Chlorella sorokiniana Cultivated Under Different CO2 Concentrations

In order to maximize microalgae biomass production and reduce its overall costs, it is important to optimize inoculum conditions based on its physical and physiological characteristics. Chlorella sorokiniana cultures inoculated with inoculum at three different physiological stages (lag, exponential, and stationary) diluted to the same optical density were cultivated for 12?days under three different CO₂ concentrations (0.038, 5, or 10?% CO₂ v/v) and growth pattern and biomass production was observed. Samples inoculated with lag phase inoculum supplied with 5?% CO₂ achieved the maximum biomass production, whereas samples supplied with 0.038?% CO₂ never reached exponential growth. The better growth of samples inoculated with lag phase inoculum was attributed to its increased number of cells compared to the other two inocula.     

Pyrolysis study of hydrophobic tholins By TG-MS, TG, DTA and DSC methods

This study presents the thermogravimetry (TG) of hydrophobic tholins, obtained from different simulation experiments of prebiotic synthesis carried out in a CH₄/N₂/H₂ atmosphere with spark discharge activation of aqueous aerosols and liquid water. Differential thermal analysis and differential scanning calorimetry were also used to evaluate the thermal behaviour of these complex organic compounds that could play an important role in prebiotic chemistry. A coupled thermogravimetry-mass spectrometry system allowed us to analyse the principal volatile thermal decomposition and fragmentation products of the hydrophobic tholins under dynamic conditions and an inert atmosphere. During their thermal degradation, which occurs in two stages, a wide variety of hydrocarbon products including methane, vinyl monomers (such as ethylene and propylene), acetylene, oligomers, and some other unknown compounds are found. Besides, a thermally stable structure is present (graphitic structure) in these particular organic substances. Finally, data collected from TG experiments in an oxidative atmosphere showed significant differences at temperatures above 240 °C. According to these results, the different techniques of thermal analysis here applied have proved to be an adequate methodology for the study and characterization of these complex systems, structures of which remain controversial even in these days.     

Radon in the spa of Bizovac

The radon concentration in the air and water of the Bizovac spa was measured by the Radhome silicon detector and the average values were obtained as 70 Bq/m³ in the indoor pool, 40 Bq/m³ in the hotel room, 135 Bq/m³ in the closed therapeutic bathroom, but the geothermal water had a Rn concentration of 25.3 kBq/m³ and the potable one 2.7 kBq/m³. The Rn transfer factor (f) from water to air in the indoor pool and therapeutic bathroom was 10 and 40 times higher than for normal dwellings (f _n=10^–4), respectively. The effective equivalent dose of inhaled radon for permanent personnel under the worst conditions in the spa was 5.4 mSv/y, but visitors spending two weeks in the spa could receive the dose of 77 Sv.     

Fe3O4 nanoparticles/ethyl acetoacetate system for the efficient catalytic oxidation of aldehydes to carboxylic acids

A new methodology for the oxidation of aldehydes promoted by commercially available Fe₃O₄ nanoparticles (Fe₃O₄ NPs) activated by ethyl acetoacetate was developed. The use of ethyl acetoacetate as additive was crucial to achieve high reactivities. All reactions were realized under solvent free conditions, using air or tBuOOH as oxidants. Finally, the separation and reuse of the magnetically recoverable nanoparticles make this methodology very practical, simple and economical.