Search

The order of magnitude of increased growth, multiplication rate, and decreased sporulation of Bacillus subtilis after exposure to nanotesla magnetic fields (MFs) relative to control samples were observed experimentally. Earth’s total magnetic field intensity was reduced from 47.9 +– 0.4 mT to cover the range from 97.5 +– 1.7 nT to 1115 +– 158 nT in eight subsequent experiments by using three pairs of Helmholtz coils combined with Mu-metal shielding. The growth, multiplication rate, sporulation, and potassium content were measured in the probe and control containing B. subtilis cultures after 24 h of exposure to nanotesla and Earth’s magnetic fields, respectively. The observed effect is discussed with regard to its possible repercussions on Earth’s living species during geomagnetic reversals that occurred when the magnetic field was much weaker than the field that exists today. In addition, effects on future manned voyages into deep space, an environment with reduced magnetic field intensity, are considered.

The International Maritime Organization’s (IMO) International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention) was entered into force in September 2017. It deals with one of the greatest threats to coastal and marine environments around the world: aquatic invasive alien species (IAS) and harmful aquatic organisms and pathogens (HAOP). Although the control of IAS and HAOP through treatment of ballast water (BW) is appropriately dealt with in the Convention and its implementation, the problems generated by sediments are not treated in such a manner. There are many published technical and scientific papers, discussions and commentaries proposing the remediation of the present situation. They are discussed, and recommendations are summarized. Besides, several systems for the treatment of BW use a combination of two or three techniques, with filtration usually being the first and/or the last step. Presence of sediments in BW results in the reduced applicability of such an approach. The requirements for sediment management procedures are discussed along with a proposal for their implementation. In the first step, the ballast tank sediments should be freed of active biological agents for the elimination of IAS and HAOP. Instead of biological agents, we advocate the use of radiation treatment by using an electron accelerator, preferably in an on-shore installation or as a mobile, additive, sea container size units with integral power, separated for water and sediment treatment. In the second step, the concentrations of heavy metals should be determined. We recommend the use of EDXRF as an analytical method. After the determination of sediment class, the recommended disposal procedures should be followed. Sediment management procedures should specify the disposal requirements: (i) free of active biological agents, IAS and HAOP; (ii) chemical composition, no chemical elements in a toxic range (≤ Class 3); and (iii) displacement/storage requirements, displacing sediments characterized as harmful in appropriate sediment reception facilities/landfills.

Objectives: To examine the effect of two aging protocols on the chemical and phase composition as well as the surface state of monolithic translucent zirconia ceramics. Material and Methods: Translucent zirconia ceramics KATANA-Zirconia STML with different surface treatments (no treatment, K1, K2; glazed, G1-G8; polished, P1-P8) underwent testing in order to examine how the two aging protocols (three-hour hydrothermal degradation in an autoclave at 134 °C and 2 bars: G1-G4, P1-P4, and sixteen-hour chemical degradation in four-percent acetic acid at 80 °C (ISO 6872): G5-G8, P5-P8) affect chemical composition, particularly the share of stabilizing yttrium oxide (Energy Dispersive XRay Fluorescence – EDXRF), phase composition (X-ray diffraction – XRD) and surface state in terms of roughness and gloss. Results: Aging protocols did not affect the tested chemical composition stability of specimens and a high share of stabilizing yttrium-oxide (≥10% of total content), which correlates with the absence of monoclinic phase. A decrease in gloss on all specimens is statistically significant. Chemical degradation substantially increased the surface roughness of tested specimens. Conclusions: Translucent monolithic zirconia demonstrated a stable chemical composition and resistance to tetragonal-to-monoclinic transformation. Surface gloss was significantly reduced, especially in polished specimens. Contrary to glazed specimens, the tested polished specimens manifested an increase in surface roughness. Glazing the surface of translucent monolithic zirconia produces better esthetic, tribological and hygienic effects than polishing.

Purpose: Measurement of carbon in cores of undisturbed sediments may provide valuable information on historical trends in sea primary production and carbonate precipitation which can be related to climate changes. Since core sediments are usually subjected to a different analysis, it is important to preserve the sample. Anon-destructive technique for carbon measurement in sedimentsbased on Fast Neutron Activation Analysis (FNAA) has been developed, which might replace the Loss-on-Ignition (LOI) as a conventional method for carbon analysis. Materials and methods: Method was tested on sediment samples collected from the Western Black Sea at depths up to 22 m. A surface sample and a corecut in centimeter intervals were freeze-dried. Samples weighing between 60 and 300 g were irradiated with the portable neutron generator. Gamma rays from 12C(n, n'γ)12C nuclear reaction were collected between 2000 and 4000 s by LaBr3:Ce detector. Standards for direct comparison and construction of the calibration line were prepared as mixtures of different amounts of quartz sand and graphite powder. FNAA results for total carbon (TC) were verified by LOIat 1000°C.LOIat 450°C and treatment with 1 M HCl were used to separate inorganic carbon (IC) and organic carbon(OC), respectively, followed by the FNAA measurements. Results and discussion: Climate effects on physical and biological marine processes are evident as historical changes in carbon flux to sediments. Carbon in sediments is found in the form of the OC produced byphotosynthetic organisms and as IC produced by calcifying organismsand precipitated as calcite. The FNAA is usually applied to samples weighing more than 1 kg. The method was optimized to reduce the minimum weight of the sample to 60 g, after subsequent adaptation of the set-up geometry.Carbon content measured in cores and surface sediment was between 2.8 and 6.1 wt%. OC constituted up to 84% of TC measured in the core.FNAA measurements were in good agreement with LOI analysis. Conclusions: The results have shown that FNAA can be used for the non-destructive determination of carbon in sediments in samples weighing ≥ 60g.FNAA is non-destructive, robust and fast in comparison to conventional methods for carbon determination such as LOI.The disadvantage is a relatively high MDL of 1%.

Prompt gamma-ray neutron activation analysis (PGNAA) has been widely used for elemental analysis of bulk samples as it provides an on-line, rapid and non-destructive means of performing such analysis. The Monte Carlo Library Least-Squares (MCLLS) approach is one of the methods for quantitative analysis providing elemental weight fractions via an assumption that the total prompt gamma-ray spectrum is a linear combination of the contributions from the individual prompt gamma-ray spectra of the sample constituents. For the generation of prompt gamma-ray libraries of each constituent, a specific purpose Monte Carlo code system called Center for Engineering Applications of Radioisotopes Coincidence Prompt Gamma-Ray (CEARCPG) is utilized. In this work, the focus was on detecting and measuring chlorine impurity in crude oil samples, i.e. trace amounts of chlorine. A preliminary study investigating the feasibility of PGNAA method in conjunction with the MCLLS approach for measuring trace amounts of chlorine in oil samples was performed. For this purpose, an extended version of the MCLLS approach, the so-called MCLLSX approach, was proposed and applied for the quantitative analysis. The results presented in this paper prove the feasibility of the proposed approach.

An important challenge in the petroleum industry is to reduce the salt content to acceptable levels in crude oil. Continuous monitoring of crude oil salinity is thus an important aspect. However, development of safe and reliable on-line and non-intrusive monitoring systems is still a challenging task. In this work, a method for non-intrusive, on-line monitoring of the chlorine impurity in crude oil based on prompt gamma-ray neutron activation analysis (PGNAA) in conjunction with a portable pulsed neutron generator producing 14 MeV neutrons in deuterium-tritium (DT) nuclear reactions is proposed and tested. Simulations with Monte Carlo N-Particle version 6 (MCNP6) transport code combined with Center for Engineering Applications of Radioisotopes Detector Response Function (CEARDRF) and a specific purpose Monte Carlo code called Center for Engineering Applications of Radioisotopes Coincidence Prompt Gamma-Ray (CEARCPG) were used for the design optimization of the experiments. Preliminary results indicate that a minimum detection limit for chlorine impurity of about 71 mg/L is achievable for an integration time of 30 min.

Concentrations of tin were measured in six different brands of disposable baby diapers by using radioisotope (americium) excited energy dispersive X-ray fluorescence. Top sheet and adhesive tape system were measured separately. The concentrations found in top sheet and tape system were

This paper presents the results of the sampling surveys carried out in order to evaluate the environmental impact of the Rude and the Sv. Jakob historical mining sites, NW Croatia. The studied polymetallic ore deposits are differing in the mineralogical and geochemical features as well as in the host rock lithology. The Rude Fe-Cu-Pb-Zn-Ba deposit is hosted by Permian siliciclastic sediments. Siderite, hematite, galena, sphalerite, chalcopyrite, pyrite, barite and gypsum are the major ore minerals, whereas quartz is the principal gangue mineral. The Sv. Jakob Pb-Zn-Ag deposit occurs in the Middle Triassic dolostone. The most abundant ore minerals are galena, sphalerite and pyrite. Calcite and quartz represent the principal gangue minerals. Although the deposits represent the potential sources of numerous toxic metals, the pollution of the drainage streams and associated stream sediments was not recorded. The studied mining sites are characterized by the high carbonate/sulfide ratios responsible for the alkaline character of the drainage streams. Consequently, the mining sites have very low potential for generation of acid mine drainage as well as very low potential for leaching of heavy metals into the drainage systems. Furthermore, the presented study revealed that the populated areas (stream waters with decreased redox potential, increased organic matter content, high NO3-, NH4+ and PO43- concentrations; stream sediments enriched in exchangeable Pb and Zn) and the Sava river alluvium (overflowing streams enriched in Hg) represent bigger environmental threat than the investigated polymetallic ore deposits.

723 sediment samples collected along the eastern Adriatic coast have been analyzed using Energy Dispersive X-Ray Fluorescence. Factor Analysis and GIS have been used for the evaluation of the resulting data base containing information on K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ga, As, Br, Rb, Sr, Y, and Pb concentration levels in order to find spatial relationships in distribution of measured elements. This study can be used to identify background values and to evaluate sediment quality standards.

A multi-sensor system was evaluated for the determination of barrel content with regard to eventual pollution hazards. The proposed system is able to investigate (in situ) the interior of a barrel filled with various unknown substances ranging from chemical and radioactive waste, raw sewage sludge, municipal incinerator ashes to common household trash. The crucial part of the system is a neutron sensor, which enables the identification of substance content without actually opening the barrel at all. A comparative laboratory test with the 3″×3″ and 5″×5″×10″ NaI(Tl) gamma ray detectors was made after which 3″×3″ detector was selected and incorporated in the submarine called “Surveyor”. A field test was made in the Croatian Adriatic coast on the island Losinj. Field tests show that the commercial system utilizing the described method could be constructed for barrel inspection regardless of the measurement environment (underwater, on land, dumping site, isolated location, etc.).

The choice of analytical method and sample pretreatment has significant consequences for the shape of particle-size distribution (PSD) frequency curves, and therefore for the evaluation of soil textural parameters. Here, the comparison of several granulometric methods based on different physical principles is presented: wet sieving (WS), based on gravity and the mechanical force of water, was combined with pipette (PP) sedimentation/settling velocity, Micromeritics SediGraph (MS) sedimentation/x-ray attenuation and Coulter Counter (CC) electroresistance particle counting. The Malvern Mastersizer (MM), an instrument based on laser diffraction, was used without WS. Twelve typical temperate-region soil types were chosen for this study on the basis of their mineral composition, organic matter content, conductivity and magnetic susceptibility. The modalities of PSD frequency curves obtained by different methods were compared. The results showed considerably larger clay-fraction contents determined with the sedimentation techniques, PP and MS, than that obtained by CC or MM. Statistical correlation and regression models were used to compare the fractions of clay, silt and sand obtained with different methods. Linear correlations were found in almost all cases, except those comparing clay fractions obtained by CC with those obtained by MM, PP and MS methods. These correlations were non-linear. The observed difference was attributed to the presence of aggregates and/or magnetic properties of soil particles. However, more data are needed to verify this hypothesis. The implications of sample pre-treatment with dispersant and hydrogen peroxide (H 2 O 2 ) were evaluated by the MS and CC techniques and observed by the scanning electron microscope. H 2 O 2 was found to be an efficient disaggregating agent. The use of dispersant resulted in the increased amount of the clay fraction measured by the MS method.

The possibility of the detection of “dirty bomb” presence inside sea containers is evaluated. The method proposed for explosive and fissile material detection makes use of two sensors (X-rays and neutrons). A commercial imaging device based on the X-ray radiography performs a fast scan of the container, identifies a “suspect” region and provides its coordinates to the neutron based device for the final “confirmatory” inspection. In this two sensor system a 14 MeV neutron beam defined by the detection of associated alpha particles is used for interrogation of only volume elements marked by X-ray sensor. The object’s nature is determined from passive and neutron induced, gamma energy spectra measurements. Experimental results (time-of-flight and gamma energy spectra) obtained for the irradiation 30 kg of TNT, depleted uranium and other materials hidden inside the container are presented.

Surface sediments and sediment cores from two bays in the Adriatic sea (Punat Bay and Soline Bay, Croatia) have been analyzed for a number of elements, in particular: Ti, V, Mn, Fe, Cu, Zn, As and Pb, by using XRF. Maps of elemental distribution in surface sediments show increased concentrations for some elements present in antifouling paints (Cu, Zn, Pb) near the service areas in the villages or marinas. Core profiles for these elements were used to evaluate the environmental impact of newly constructed marinas. Source partition indicates the influence of other sources located in near by villages. The critical factor in these considerations was shown to be water exchange with the open sea.

It has been observed that among the seven municipalities of the Island of Krk the three in the central part of the island have increased disease incidence rates for the five groups of diseases: (a) neoplasm, (b) diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism, (c) endocrine, nutritional and metabolic diseases, (d) mental and behavioral disorders and (e) diseases of the circulatory system. One of the etiological factors is assumed to be the influence of the geochemical environment. The average element concentration values of six trace elements (Mn, Fe, Ni, Cu, Zn and As) for the geochemical environment in the individual municipalities were determined by XRF analyses of soil, plant, potable water and hair samples. The data on disease incidence rates for the individual municipalities, from 1997 to 2001, have been obtained from the Public Health Institution in charge of monitoring population health on the island. Diseases' groups have been defined by the WHO methodology. The GPS-GIS methodology was used to obtain maps of trace elements in different matrices and disease incidence distributions. Data analyses were performed by multivariate statistical methods (principal component analysis and cluster analysis). It has been shown that the concentration levels of the elements could be related to disease incidence rates.

In this paper we analyzed characteristics of 6 different soils from the test field at the Ruđer Boskovic Institute. Many soil properties relevant for the performance of humanitarian demining tools strongly depend on water content. This is an effort to understand better the soil moisture variability and to find soil parameters that can predict the water content regarding the weather conditions. Such knowledge will allow to optimize demining operations. To gather the main parameters like field capacity, rate and delay of water infiltration and soil water retention which are all related to soil texture, daily time-series of soil moisture from August to November 2001, where analyzed.

Samples of soil, plant material and water collected on the Croatian island Krk in northern Adriatic sea were analyzed for a number of chemical elements (Ca, Ti, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Zr, Pb) by using Energy Dispersive X-Ray Fluorescence as an analytical tool. Some of these data have been previously used to produce geochemical map of the island. In addition, trace elements content of hair from children, attending elementary and secondary schools, has been investigated using the same analytical method for the following chemical elements: Mg, S, Ca, Cr, Mn, Fe, Ni, Cu, Zn, As, Hg and Pb. Concentrations of the twelve chemical elements and nine variables from the questionnaire, i.e. age, sex, living place, transportation, medication, hair colour, hair type, type of shampoo used and hair treatment, were considered in the statistical analysis. In this report the observed differences for the seven island's communes have been discussed.

The detection of landmines by using available technologies is a time consuming, expensive and extremely dangerous job, so that there is a need for a technological breakthrough in this field. Atomic and nuclear physics based sensors might offer new possibilities in de-mining. Among the available nuclear techniques, the neutron backscattering technique (NBT), based on the detection of the produced thermal neutrons, is thought to be the most promising for field applications. We discuss here two limitations of NBT, being related to the soil moisture. First, the critical value of the soil moisture, reached when the density of the hydrogen atoms in the landmine is equal to that in the background soil, defines a condition for which the detection is not possible. Critical values are small for some of the landmine types, thus suggesting the application of the method to arid countries, where the soil moisture is lower than 10%. Furthermore, small-scale variations of the soil moisture content, experimentally determined for different soil types, are found to be capable of generating false positive readings. To avoid this problem, the integration of the NBT with a second sensor, as the metal detector, is proposed.