Design and investigation of a continuous radon monitoring network for earthquake precursory process in Great Tehran

Earthquakes usually occur after some preliminary anomalies in the physical and chemical characteristics of environment and earth interior. Construction of the models which can explain these anomalies, prompt scientists to monitor geophysical and geochemical characteristics in the seismic areas for earthquake prediction. A review of studies has been done so far, denoted that radon gas shows more sensitivity than other geo-gas as a precursor. Based on previous researches, radon is a short-term precursor of earthquake from time point of view. There are equal experimental equations about the relation between earthquake magnitude and its effective distance on radon concentration variations. In this work, an algorithm based on Dobrovolsky equation $ (D = 10^{0.43M} ) $ with defining the Expectation and Investigation circles for great Tehran has been used. Radon concentration was measured with RAD7 detector in the more than 40 springs. Concentration of radon in spring, spring discharge, water temperature and the closeness of spring location to active faults, have been considered as the significant factors to select the best spring for a radon continuous monitoring site implementation. According to these factors, thirteen springs have been selected as follow: Bayjan, Mahallat-Hotel, Avaj, Aala, Larijan, Delir, Lavij, Ramsar, Semnan, Lavieh, Legahi, Kooteh-Koomeh and Sarein.     

Uranium groundwater anomalies and active normal faulting

The ability to predict earthquakes is one of the greatest challenges for Earth Sciences. Radon has been suggested as one possible precursor, and its groundwater anomalies associated with earthquakes and water?Crock interactions were proposed in several seismogenic areas worldwide as due to possible transport of radon through microfractures, or due to crustal gas fluxes along active faults. However, the use of radon as a possible earthquake??s precursor is not clearly linked to crustal deformation. It is shown in this paper that uranium groundwater anomalies, which were observed in cataclastic rocks crossing the underground Gran Sasso National Laboratory, can be used as a possible strain meter in domains where continental lithosphere is subducted. Measurements evidence clear, sharp anomalies from July, 2008 to the end of March, 2009, related to a preparation phase of the seismic swarm, which occurred near L??Aquila, Italy, from October, 2008 to April, 2009. On April 6th, 2009 an earthquake (M_w = 6.3) occurred at 01:33 UT in the same area, with normal faulting on a NW?CSE oriented structure about 15 km long, dipping toward SW. In the framework of the geophysical and geochemical models of the area, these measurements indicate that uranium may be used as a possible strain meter in extensional tectonic settings similar to those where the L??Aquila earthquake occurred.     

Optimization of time resolution and detection limit for online measurements of 222Rn in water

The online measurements of radon in flowing water with high temporal resolution and a lower limit of detection of some Bq/l is of growing interest in environmental research and earth sciences. Promising new fields of application in hydrogeology are the study of exchange and mixing processes and the monitoring of pumping procedures before and during groundwater sampling. A suitable, simple method has been proposed by Surbeck based on the separation of air and water by a diffusion membrane. Process parameters influencing the temporal resolution as well as the radon detection efficiency have been studied. Considering these results a new instrument has been developed enabling online radon-in-water measurement with time resolution of about one minute.     

Peculiar radon spot in Hungary

For the public, indoor radon is the main source of exposure from ionizing radiation. Radon gas originates from the radioactive decay chain of uranium deposited in rocks or in building materials. In the reviews mostly a rather steady radon exhalation has been assumed. In a village of North-East Hungary, however, high radon concentrations have been measured, differing strongly in neighbouring houses and varying in time, due to the interplay of several geochemical phenomena.     

A novel detection of radon based on its decay product inducing conformational changes of an aptamer probe

This study proposes a novel method for the detection of inert gas radon using a label-free, specific, fluorescence-sensing aptamer in the context of PW17-OG system. This method utilizes the cyanine dye OliGreen (OG) as a signal reactor and the aptamer PW17 as a fluorescent identification probe. When OG integrates into the free curling PW17, a strong fluorescence signal is generated. After radon decays, the long lived naturally occurring radon progeny Pb being disposed and introduced to the system. Lead ions induce PW17 to form a stable G-quadruplex, thereby inhibiting the interaction between OG and PW17 and resulting in a reduction of the fluorescence intensity. The fluorescence intensity show a good linear relationship with lead ion and the radon concentration (D), thereinto, We fitted linear regression of radon concentration in the range of 0.92–4.22 (×10⁴ Bqhm⁻³) to receive a good relationship between ΔF and the concentration of radon with the detection limit of 1963 Bqhm⁻³. This method has been successfully applied for detecting standard cumulative concentration of radon and the detection limit reached the national standard of China. This sensitive method can exclude radiation damage in field testing, furthermore, it explores a new field in biological analysis using an aptamer to detected inorganic, gaseous, and radioactive materials.     

Indoor radon concentration levels in Mexican caves, using nuclear track methodology, and the relationship with living habits of the bats

This work presents the results of a study of the radon levels in four caves in Mexico: Los Riscos Cave and El Judío Cave in the State of Querétaro, and Coyozochico Cave and Karmidas Cave in the State of Puebla. The measurements were made using the passive closed-end cup system, with CR-39 (Lantrack^®) as detection material, and following protocols established for the measurement of indoor radon, developed at the Dosimetry Applications Project of the Physics Institute of the Universidad Nacional Autónoma de México. The radon concentration at one location with Karmidas Cave reached more than 60,000 Bq/m³, while concentrations in the other three caves varied from 83.1–1216.0 Bq/m³, was found. During the study was observed an interesting coincidence between the radon concentration distribution inside the caves, and the bat colonies location. In general, the bat colonies are located at the medium or low radon concentration levels zones.     

Radon concentration of outdoor air: measured by an ionization chamber for radioisotope monitoring system at radioisotope institute

Gas-flow ionization chambers for radioisotope (RI) monitoring systems at RI institutes throughout Japan are commonly used to measure RIs which leak from the RI institutes. Before the Japan’s 2011 Tohoku earthquake [11 March 2011, moment magnitude (M _w) 9.0], ionization current data measured with a gas-flow ionization chamber at the RI institute of Fukushima Medical University were found to change. The question we must raise is whether the variation ionization current can be considered to the variation of outdoor radon concentration. The conversion factors (from ionization current to radon concentration in air) of the gas-flow ionization chamber can be obtained by measuring four levels of radon concentration (outdoor air, indoor air, high level and radon-free gas) with an AlphaGUARD monitor and the chamber itself. The two gas-flow ionization chambers consist of the air intake and terminal exhaust duct of the RI institute. It was found that the radon concentration in the exhaust air was the same as that in the air intake. This study provided evidence that variations of outdoor radon concentration could be determined using gas-flow ionization chambers for RI monitoring systems.     

Radon levels assessment in some Northern Romanian salt mines

Due to their low radioactivity background, underground salt mines spaces offer a unique possibility for speleotherapy use. The knowledge of radon concentration levels in such underground environments is essential for therapeutic purposes of different respiratory and rheumatic diseases. In order to develop speleotherapy in Romania, this paper presents the results of an indoor radon concentration levels survey in some salt mines in Romania. The survey was carried out using radon monitor Pylon AB-5 system methodology validated by a CIS-P5M system. In order to investigate whether differences in depth and microclimate parameters translate into significant differences in salt mine indoor radon concentrations, have been chosen three salts mine test sites placed in the Northern part of Romania (Turda, Cacica and Ocna Dej) in stable areas of the mining field at 32?C120?m depth. Environmental microclimate conditions (mean values of air temperature 10?C14.5?°C, air humidity 65?C80%, air velocity 0.2?m/s saline aerosols and low microbial factors) have anti-bacterial, anti-microbial, and anti-inflammatory properties and recognized therapeutically effects on human body??s health. Air temperature is one of the most important factors which need to be considered when carrying out a survey of indoor radon concentrations in salt mines because temperature largely determines close spaces ventilation rates, and ventilation habits are known to have significant effects on indoor radon concentrations. The analyzed environmental conditions and recorded low levels of indoor mean radon concentration (6.9?±?0.39 and 96.5?±?4.76?Bq/m³) demonstrated the best suitability of the investigated three salt mines in Romania for speleotherapeutic applications.     

Ultrasound monitoring of the cure kinetics of an epoxy resin: Identification,frequency and temperature dependence

In this paper the monitoring of ultrasonic parameters of a thermosetting resin during an isothermal curing process is described. The ultrasonic properties are studied within the context of the monitoring of composite plate production by resin transfer molding (RTM). These ultrasonic characteristics can be related directly to cure kinetic models. An ultrasonic method, based on the measurement of the elastic constant and associated mechanical loss has been developed to identify the variations of the phase transformation. To study the reaction kinetics, the time dependence of the elastic coefficient is modeled using a Weibull distribution. The approximate time derivative form of this Weibull model makes it possible to find the relationship between ultrasonic parameters and the chemical Kamal model. The ultrasonic monitoring of a cooling process was also performed to study the temperature sensitivity after curing. Thanks to experimental measurements of the ultrasonic velocity and attenuation, the power law coefficient variations and their temperature sensitivity can be examined. The resulting viscoelastic Cole-Cole parameters were estimated and a frequency-temperature (f, T) model was proposed.     

Fluorinated compounds for advanced IC interconnect applications: a survey of chemistries and processes

The semiconductor industry is now in the early stages of an unprecedented change in materials set for the integrated circuit (IC) interconnect structure. The traditional layers of aluminum conductors and silicon dioxide dielectrics are being replaced by copper thin films and a variety of low k candidates, respectively. In many cases, fluorine confers desirable properties on either the precursors or the final films. At the same time, fluorine presents some potentially adverse effects, which have led to a so-called “fear-of-fluorine” in interconnect applications. This paper will review the proposed uses of fluorinated compounds in the interconnect structures, covering both precursors and the resulting thin films. Both the status of technical studies, and the prospects for commercial implementation, will be addressed.     

Emanation studies of radium containing materials by a simple radon monitoring system

The applicability of a radon emanation system to radium determination in fine-grained solid samples has been investigated by means of a closed radon emanation system consisting of a radon monitor and an aluminium vessel. The system has been calibrated with radium-containing fine-grained samples (e.g. phosphogypsum, granite and pitchblende) and the evaluation of the calibration data included linearity, detection limits and analytical resolution of the method. The studied radon emanation system presents very good linear response (R ² = 0.99) to the radium content of the samples, the detection limit for radon is 25 Bq m^?3 and the analytical resolution 15 Bq m^?3. In addition, the relation between particle size of the materials and radon emanation has indicated that the applicability of the radon emanation system to radium determination is strongly depended not only on the mineral type but also on the particle size of the grained material.     

Study of the influence of the lithological and hydrogeological parameters of aquifers on the radon emanation from underground waters using solid state nuclear track detectors

Radon-to-thoron ratios as well as radon and thoron activity concentrations in different underground water samples belonging to different aquifers in the Moroccan Middle Atlas area have been evaluated by LR-115 and CR-39 solid state nuclear track detectors (SSNTD) using a new calibration method. The radon isotope (²²²Rn) was used as a tracer for studying the water exchange between different aquifers of the area studied. The influence of the lithological and hydrogeological parameters of the aquifers on radon emanation were investigated.     

Chirality at octahedral centres determined by tetradentate Schiff base ligands

1,2-bis(2′-aminophenoxy)-4-methylbenzene provides a Schiff base by reaction with 2-pyridinecarboxaldehyde. The stereochemical rigidity of ortho-aminophenyl diamines causes this latter, as well as the corresponding nitro precursors, be chiral. The chiral conformation of the diamine precursor is maintained in the octahedral zinc(II) and cobalt(II) complexes prepared from the Schiff base. The crystal structures of [ZnL(NO₃)(H₂O)]NO₃ and CoLCl₂ complexes exhibit non-planar cis-α configurations with both enantiomers (Δ and Λ). This implies that in the Schiff base ligand the two α-diimine systems shape an octahedral cavity having the same chirality of the precursory diamine.     

On the vapour pressure of radon

The few, rather scarce, and old data on the vapour pressure and sublimation pressure of radon are re-examined in light of the Wagner equation, which is applied for the first time (as far as we are aware) to the sublimation curve. Numerical coefficients have been established for the representation of both equilibrium curves, and estimates are advanced for the coordinates of the critical point, the triple-point, and the normal boiling temperature of radon. Some important thermodynamic properties, e.g., the enthalpies of vaporisation, sublimation, and fusion are derived, and a (p, T) phase diagram is sketched.     

Radon concentration in well water from Namom district (Southern Thailand): a factor influencing cancer risk

The radon concentrations were determined in well water samples from Namom district, Southern Thailand, by using a RAD7 radon monitoring system. The measured values ranged from 0.1 to 483.0 Bq l^?1, while the average ±1σ across all measured samples was 32.0 ± 9.2 Bq l^?1. Regarding the health risks from radon in household drinking water, some settlements had radon concentration exceeding 100 Bq l^?1, an upper limit set by the European Union Directive EC2013/51/EURATOM. It is of concern that the results indicate health risks, especially to those consumers who directly use well water with high radon concentration.     

Deposition and extension approach to find longest common subsequence for thousands of long sequences

The problem of finding the longest common subsequence (LCS) for an arbitrary number of sequences is a very interesting and challenging problem in computer science. This problem is NP-complete, but because of its importance, many heuristic algorithms have been proposed, such as Long Run, Expansion Algorithm and THSB. However, the performance, either in result quality or in process time, of many current heuristic algorithms deteriorates fast when the number of sequences and sequence length increase. In this paper, we have proposed a post-process heuristic algorithm for the LCS problem, the Deposition and Extension Algorithm (DEA). This algorithm first generates common subsequence by “sequence deposition” based on fine tuning of search range, and then extends this common subsequence. The algorithm is proven to generate Common Subsequences (CSs) with guaranteed lengths. The experiments on different dataset showed that the results of DEA algorithm were better than those of Long Run and Expansion Algorithm, especially on many long sequences. The algorithm also had superior efficiency both in time and memory space.     

Radon measurements in water samples from the thermal springs of Yalova basin, Turkey

The radon concentration has been measured in thermal waters used for medical therapy and drinking purposes in Yalova basin, Turkey. Radon activity measurements in water samples were performed using RAD 7 radon detector equipped with RAD H₂O (radon in water) accessory and following a protocol proposed by the manufacturer. The results show that the concentration of ²²²Rn in thermal waters ranges from 0.21 to 5.82 Bql^?1 with an average value of 2.4 Bql^?1. In addition to radon concentration, physicochemical parameters of water such as temperature (T), electrical conductivity, pH and redox potential (E_h) were also measured. The annual effective doses from radon in water due to its ingestion and inhalation were also estimated. The annual effective doses range from 0.2 to 0.75 μSvy^?1 for ingestion of radon in water and from 2.44 to 9 μSvy^?1 for inhalation of radon released from the water.     

Facile method for synthesis of mixed-cation halide perovskites by mild equilibrium conversion via iodine-mediated transport reaction in inert liquid media

A new facile method for the synthesis of mixed-cation halide R2 = 0.9935 perovskites based on the chemical conversion of solid precursors (organic halides and lead halides) via an iodine-mediated transport reaction in inert liquid media under mild conditions is described. The equilibrium nature of the conversion provides an exact match between the stoichiometry of the resulting perovskite powder and the molar ratio of the precursors. This method can serve as a useful tool for the synthesis of complex perovskite precursors and the investigation of phase equilibria     

Aromatic hydrocarbons from geological sources—I : New naturally occurring phenanthrene and chrysene derivatives

The phenanthrene and chrysene derivatives 1 and 2 have been identified in the Messel oil shale by comparison with synthesized reference compounds. These molecules have most probably been formed by progressive geochemical aromatization of triterpene precursors of the hopane series which is widespread in the geological environment.     

Environmental radioactivity survey in site studies

Systematic monitoring of Rn in soil, background gamma levels and meteorological measurements, have been conducted at the site of a Nuclear Research Center. The data cover a time period of several years. The radon in soil gas fluctuations are influenced by meteorological seasonal changes and by geophysical local parameters and they range between 1000 Bq/m³ and 18000 Bq/m³. The observed gamma levels show geographic stability; some seasonal fluctuations were observed. Data analysis indicates that no significant changes occurred at the site over the measuring time period and radiation levels and meteorological changes are moderate inducing no ecological impact on the surroundings.