Narrow Results

Selenium in industrial wastewater at sub-ppm level was determined by PIXE spectrometry at the Tokyo Institute of Technology Van de Graaff Laboratory using a 2.5 MeV proton beam. A chemical concentration method was applied for elemental analysis. Other elements (Mn, Fe, Ni, Cu, Zn, Pb, Hg, Cd, As) were also found simultaneously. Anion chromatography revealed that selenium forms an oxyanion SeO₃^2- in wastewater studied. Pb, As and Se of these chemical species are required to lower below the discharge standard to the public water, 0.1ppm, while that of Hg is 0.005ppm. The combined use of these two analysis tools will help for rapid monitoring of the quality in the public water environment.

Tailings from an indigenous mining community were analyzed by PIXE to study the residual amount of gold and to check the relative increase in mercury content after the mineral dressing. The result showed that gold is sometimes left in the tailings at ore-grade concentration up to 30 ppm, and that relative mercury content is not increasing drastically. Since the tailings are trade target in the local community, it would be necessary for stakeholders to have a common and fair facility where they can assay gold content of the tailing at regular interval.

Artisanal/small-scale gold mining is one of the important livelhood for deprived people in many countries. The activity is expected to support people's life and activate local economy. However amalgamation method is common to recover gold in this type of mining, and due to this practice, mercury is being released into the natural environment. During the ore treatment process, miners uptake mercury not only by inhalation of the vapor but also by absorption of liquid mercury through the skin. In order to cope with health problems and environmental damages arising from the use of mercury, there should be coordination between national/local government, aid agencies and scientific institutes. In addition, the environmental education and risk communication are keys to mitigate the environmental damage by the miners. For such purpose, quick and precise trace element analysis as a base of discussion on occupational health risk is indispensable and our trial proved that PIXE is one of the most flexible and versatile system. In this paper examples of trial through a Japan-Philippines partnership will be presented.

Aquatic insects, such as caddisflies, are used as reference organisms for water pollution. The precise distribution of contaminated metals in the insect, however, remains unknown. In this study, we used micro PIXE analysis to examine mercury distribution in Stenopsyche marmorata, a typical caddisfly, exposed to mercuric chloride. The mercury level in the caddisflies after exposure to mercuric chloride at 1 mg/L for 5 days was 93.3 ± 25.0 μg/g wet weight. Micro PIXE analysis also revealed a site-specific distribution of mercury in the insects. Mercury was high in the digestive tract, where it was localized in the basement membrane and the peritrophic membrane. Mercury was also detected in the tissue surrounding the digestive tract. Further examination of the tissue identified mercury in the fat body but not in the silk gland.

Elemental concentrations in some herbal medical products, produced by different ayurvedic pharmacies in India, were determined using Energy Dispersive X-Ray Fluorescence Spectrometry (EDXRF). All the eight products, which were studied, contained mercury, and four out of the eight products contained arsenic in varied amounts. Daily mercury and arsenic intakes by the patients taking these products, determined from the doses prescribed by the manufacturers, exceeded the recommendations by WHO. The present work does not argue on the toxicity of heavy metals in drugs but gives information about the presence of heavy metals at levels more than the required recommendations by various health regulatory bodies. This level of As and Hg calls for caution as far as their safe intake is concerned.

After the conclusion of the Minamata Convention on Mercury, the use of mercury (Hg) has been prohibited worldwide, except in some developing countries. The Republic of the Philippines is one of the 128 signatories of the Convention. There are many artisanal and small-scale gold mining (ASGM) operations in the Philippines that still use Hg to amalgamate gold. In order to know the direct effect of exposure to Hg on women’s hair, we performed the proton-induced X-ray emission analysis of Hg concentrations in the hair samples collected from women at risk of Hg contamination, in both ASGM and non-ASGM areas in Camarines Norte, Philippines. At the same time of the hair sampling, we also conducted interviews with the women about their lives. From the analysis results, we found that the range of Hg concentrations in the hair samples was at a safe level, with no significant difference between the ASGM and non-ASGM areas. An analysis of the effect of diet on Hg concentrations in the hair samples showed a tendency toward higher Hg concentrations in women who ate more fish. Our results through hair analysis did not show a direct effect of exposure to atmospheric Hg, but further survey of local people should be necessary to reduce the risk of Hg contamination in women even after the use of Hg in ASGM eventually comes to an end.

The method of increments is a wavefunction-based ab initio correlation method for solids, which explicitly calculates the many-body wavefunction of the system. After a Hartree-Fock treatment of the infinite system the correlation energy of the solid is expanded in terms of localised orbitals or of a group of localised orbitals. The method of increments has been applied to a great variety of materials with a band gap, but in this paper the extension to metals is described. The application to solid mercury is presented, where we achieve very good agreement of the calculated ground-state properties with the experimental data.

This review is in general about group 12 elements and their small microclusters. In this part, after presenting an extensive literature survey of the electric dipole polarizability studies of the Zn, Cd and Hg atoms, we specifically target zinc-containing small clusters, beginning with the Zn₂ dimer, the Zn₃ trimer, higher Zn_n clusters and the neutral, cationic and anionic zinc oxide clusters: ZnO, ZnO⁺ and ZnO^-. We tabulated experimental and theoretical results for the spectroscopic constants (dissociation energy D_e or D₀, bond length r_e, fundamental frequency w_e, anharmonicity constant w_ex_e and dipole moment μ_e) of the diatomic clusters and the first and second ionization potentials IP₁ and IP₂ and electron affinity EA of the species reviewed.

A mole of Mercury was suitably treated by ultrasound in order to generate in it the same conditions of local Lorentz invariance violation that were generated in a sonicated cylindrical bar of AISI 304 steel and that are the cause of neutron emission during the sonication. After 3 min, part of the mercury turned into a solid material which turned out to contain isotopes having a different mass (higher and lower) with respect to the isotopes already present in the initial material (mercury). These transformations in the atomic weight without gamma production above the background are brought about during Deformed Space–Time reactions. We present the results of the analyses performed on samples taken from the transformation product. The analyses have been done in two groups, the first one using five different analytical techniques: ICP-OES, XRF, ESEM-EDS, ICP-MS, INAA. In the second group of analyses, we used only two techniques: INAA and ICP-MS. The second group of analyses confirmed the occurring of the transformations in mercury.

The validity of General Relativity (GR), after 100 years, is supported by solid experimental evidence. However, there is a lot of interest in pushing the limits of precision by other experiments. Here, we focus our attention on the equivalence principle (EP), in particular, the strong form. The results of ground experiments and Lunar Laser Ranging (LLR) have provided the best upper limit on the Nordtvedt parameter $\eta$ that models deviations from the strong EP. Its uncertainty is currently $\sigma [\eta ]=4.4\times 10^{-4}$. In the first part of this paper, we will describe the experiment, to measure $\eta$, that will be done by the future mission BepiColombo (BC). The expected precision on $\eta$ is $\approx 10^{-5}$. In the second part, we will consider the ranging between the Earth and a spacecraft (SC) orbiting near the Sun–Earth Lagrangian points to get an independent measurement of $\eta$. In this case, we forecast a constraint similar to that achieved by LLR.

In the last century, mercury levels in the global environment have tripled as a result of increased pollution from industrial, occupational, medicinal and domestic uses.¹ Glutathione is known to be the main agent responsible for the excretion of mercury (Refs. 2 to 4). It has also been shown that mercury inhibits glutathione synthetase (an enzyme acting in the synthesization of glutathione), therefore leading to decreased glutathione levels (Refs. 5 to 7). Mercury also interferes with the production of heme in the porphyrin pathway.⁸ Heme is needed for biological energy production and ability to detox organic toxins via the P450 enzymes.⁹ The purpose of this paper is to show that the body's response to mercury exposure is hysteretic, i.e. when this feedback of mercury on its main detoxifying agents is strong enough, then mercury body burden has two points of equilibrium: one with normal abilities to detoxify and low levels of mercury and one with inhibited abilities to detoxify and high levels of mercury. Furthermore, a small increase of the body's mercury burden may not be sufficient to trigger observable neurotoxic effects but it may be sufficient to act as a switch leading to an accumulation of mercury in the body through environmental exposure until its toxicity is manifested.

Density functional theory calculations are performed to provide a molecular-level understanding of the mechanism of mercury adsorption on sulfuric acid-impregnated carbonaceous surface. The carbonaceous surface is modeled by a nine-fused benzene ring in which its edge carbon atoms on the upper side are unsaturated to simulate the active sites for reaction. SO₄ clusters with and without charge are examined to act as the representative species to model the sulfuric acid absorbed on the carbonaceous surface. All of the possible approaches of SO₄ clusters with and without charge on the carbonaceous surface are conduced to study their effects on mercury adsorption. The results suggest that sulfuric acid effect on the mercury adsorption capacity of the carbonaceous surface is very complicated, and it depends on a combination of concentration and charge of SO₄ cluster. SO₄ cluster presents a positive effect on mercury adsorption on the carbonaceous surface, but higher concentration of SO₄ cluster decreases the adsorption capacity of the carbonaceous surface for mercury removal because there is considerable competition for active sites between Hg and SO₄ cluster. Since all of the possible approaches of mercury on the carbonaceous surface with cluster, excluding one that mercury is adsorbed at bridge active site, can lead to the decrease in the adsorption energies of mercury on the carbonaceous surface, cluster presents a negative effect on the capacity of the carbonaceous surface for mercury adsorption regardless of the concentration of cluster. The results also indicate that SO₂ cluster and surface oxygen complex can be formed from SO₄ cluster with or without charge if mercury is adsorbed at bridge active site, which facilitates the mercury removal for the carbonaceous surface.

Recent research has shown that fly ash may catalyze the oxidation of elemental mercury and facilitate its removal. However, the nature of mercury-fly ash interaction is still unknown, and the mechanism of mercury retention in fly ash needs to be investigated more thoroughly. In this work, a fly ash from a coal-fired power plant is used to characterize the inorganic and organic constituents and then evaluate its mercury retention capacities. The as-received fly ash sample is mechanically sieved to obtain five size fractions. Their characteristics are examined by loss on ignition (LOI), scanning electron microscope (SEM), energy dispersive X-ray detector (EDX), X-ray diffraction (XRD), and Raman spectra. The results show that the unburned carbon (UBC) content and UBC structural ordering decrease with a decreasing particle size for the five ashes. The morphologies of different size fractions of as-received fly ash change from the glass microspheres to irregular shapes as the particle size increases, but there is no correlation between particle size and mineralogical compositions in each size fraction. The adsorption experimental studies show that the mercury-retention capacity of fly ash depends on the particle size, UBC, and the type of inorganic constituents. Mercury retention of the types of sp² carbon is similar to that of sp³ carbon.

Copper oxide (CuO) is proved to be a potential adsorbent for elemental mercury in the flue gas emitted from coal-fired power plant. However, the O-terminated CuO(110) surface has relatively week adsorption capacity for Hg. In this work, the doped method is applied to enhance the mercury adsorption capacity of O-terminated CuO(110). Mn, Si, Ti, Al and Zn are selected as the doped atom. It is found that only Zn-doped CuO (110) surfaces have the higher adsorption energy than the pure O-terminated CuO(110) surface. The mercury adsorption capacity is a complex issue, which depends on a combination of oxygen and doped element. The results suggest that the lower electropositive doped element is favorable for the improvement of mercury adsorption capacity. However, the lower electronegativity of oxygen atoms does not facilitate the mercury capture, which is different from the organic material. Cu and doped metal element, rather than oxygen atom, mainly determine mercury adsorption capacity of O-terminated CuO(110) surface, which leads to the lower adsorption capacity of the O-terminated CuO(110) surface than the Cu-terminated CuO(110) surface. The conclusions can also offer a valuable reference for the other metal oxide regarding mercury capture.

A series of (Fe${}_{2.2}$Mn${}_{0.8}$Cu${}_x{)}_{1-\delta }$O₄ ($x=0$, 0.2, 0.5, and 0.8) was synthesized for elemental mercury capture. The as-synthesized adsorbents were characterized by Brunauer–Emmett–Teller (BET), powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The experimental results show that (Fe${}_{2.2}$Mn${}_{0.8}$Cu${}_{0.5}{)}_{1-\delta }$O₄ catalyst adsorbent exhibits the best elemental mercury capture capacity with the increase in mercury removal efficiency by 20% as compared to the (Fe${}_{2.2}$Mn${}_{0.8}{)}_{1-\delta }$O₄ adsorbent. The XPS results indicate Cu dopant can provide the lattice oxygen on the adsorbent surface due to the transformation from Cu${}^{2+}$ cations to Cu${}^{+}$ cations, which increases the active sites for elemental mercury adsorption. The Mn${}^{4+}$ cations on the adsorbent surface may oxidize the adsorbed mercury to mercury oxidization. Meanwhile, the Mn${}^{3+}$ cations formed are also oxidized to the Mn${}^{4+}$ cations by the gaseous oxygen phase in the reactor gas. However, the large Cu content may block the collision between Mn${}^{4+}$ cations and adsorbed mercury, and thus decrease the oxidization capability of adsorbent surface for mercury. Therefore, the Cu dopant with the suitable content may be a potential modified method for the adsorbent to further increase the elemental mercury capture.

Sheep Genome Project Begins.

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Chinese Scientists Diagnose Cancer through Urine Tests.

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China Aims Growing Human Organs by Cloning.

Silicon Chip to Genotype Chinese Medicinal Plants.

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Singapore Varsity Grows hES Cell without Animal Input.

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Japan to Establish Human Stem-cell Bank.

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Thai Study Finds Mercury in Shark Fins.

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Record Number of Hepatitis C Infections in Australia.

Needle Schemes Prevents HIV and HCV Infections.

Sino-French Life Sciences Center Established.

Ten Percent of HK Students Have High Mercury Exposure.

India Emerges as Biotech R&D Hub.

Adult Smoking Rate at All-time Low.

Japan’s Nobel Laureates Hope to Inspire Science Boom.

NZ Lays out Biotechnology Strategy.

IRRI Sets up Rice Knowledge Bank.

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Singapore Sets Up Oncology Research Institute.

Agrobiology Scientists Move into New Institution.

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Biological and Medical Engineering Conference in Singapore.

Taiwan Shares Malaria Experience.

India to Combat Spurious Drugs.

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Free Cancer Checkups for Some Koreans.

Korean Authority to Manage Anti-Cancer Treatments.

China’s 2002 Pharmaceutical Market.

Punjab Government Plans to Set Up Biotech Board.

Andhra and LIC Join Hands for VC Fund.

Harmful Level of Mercury in Whale Meat.

Korea to Reduce Milk Production.

New Biotech Valley in Malaysia.

Tightened Measures Against Canadian Beef and Related Products Import.

Biotechnology Taskforce Named.

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Two Scientists Share China’s Top Science Award.

Vice Premier Liu Urged to Accelerate Innovation-driven Development in China.

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China Donates Mobile Clinics to Kenya.

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