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PubMed2001

Synthesis, structure, and properties of Cs(4)Th(4)P(4)Se(26): a quaternary thorium selenophosphate containing the (P(2)Se(9))(6-) anion.

Orange crystals of Cs(4)Th(4)P(4)Se(26) were grown from the reaction of (232)Th and P in a Cs(2)Se(3)/Se molten salt flux at 750 degrees C. Cs(4)Th(4)P(4)Se(26) crystallizes in the orthorhombic space group Pbca with the unit cell parameters: a = 12.0130(6), b = 14.5747(7), c = 27.134(1) A; Z = 8. The compound exhibits a three-dimensional structure, consisting of dimeric [Th(2)Se(13)] polyhedral units. The two crystallographically independent, nine-coordinate, bicapped trigonal prismatic thorium atoms share a triangular face to form the dimer, and each dimer edge-shares two selenium atoms with two other dimers to form kinked chains along the [010] direction. While this structure shares features of the previously reported Rb(4)U(4)P(4)Se(26), including phosphorus in the 5+ oxidation state, careful inspection of the structure reveals that the selenophosphate anion that knits the structure together in three directions in both compounds is a unique (P(2)Se(9))(6-) anion. The formula may be described best as [Cs(2)Th(2)(P(2)Se(9))(Se(2))(2)](2). The (P(2)Se(9))(6-) anion features a nearly linear Se-Se-Se backbone with an angle of 171 degrees and Se-Se distances that are approximately 0.2-0.3 A longer than the typical single Se-Se bond. Magnetic studies confirm that this phase contains Th(IV). Raman data for this compound is reported, and structural comparisons will be drawn to its uranium analogue, Rb(4)U(4)P(4)Se(26).

Journal Article↗
PubMed1998

Syntheses, Crystal Structures, and Physical Properties of the New Thorium Chalcogenides CuTh(2)Te(6) and SrTh(2)Se(5).

Single crystals of CuTh(2)Te(6) form by a stoichiometric reaction of the elements at 1000 degrees C. The compound crystallizes in the space group -P2(1)/m with unit cell parameters a = 6.170(2) Å, b = 4.332(1) Å, c = 10.424(3) Å, beta = 98.85(1) degrees, and Z = 1 at 113 K. The structure was solved from single-crystal X-ray data. It consists of layers of [Th(2)Te(6)(-)] double chains joined by Cu(+) cations. Each Th atom is coordinated to eight Te atoms in a bicapped trigonal prismatic arrangement. There are three crystallographically unique Te atoms. Each ThTe(8) unit is bridged through one distinct Te atom, such that the capping Te atom of one unit forms the vertex of its neighbor. The two nonbridging Te atoms form infinite Te-Te chains along the exterior of the [Th(2)Te(6)(-)] layer. Copper atoms are coordinated to these Te atoms in a tetrahedral arrangement. Owing to the existence of Te-Te bonds of intermediate length, the assignment of formal oxidation states in this compound is not possible. Four-probe dc electrical conductivity measurements of a single crystal of CuTh(2)Te(6) indicate the compound is a semiconductor along [010]. Magnetic susceptibility measurements in the range 2-300 K show CuTh(2)Te(6) to be paramagnetic with &mgr;(eff) = 2.06 &mgr;(B) at 300 K. Single crystals of SrTh(2)Se(5) form from the reaction SrSe + Th + 3Sn + 3Se at 1000 degrees C. EDAX experiments show no tin present in several crystals analyzed. Transparent red blocks of SrTh(2)Se(5) crystallize in the space group -P2(1)/c with unit cell parameters a = 8.704(2) Å, b = 7.861(2) Å, c = 12.458(4) Å, beta = 90.00(2) degrees, and Z = 4 at 113 K. The structure, which is related to that of U(3)S(5), is a three-dimensional framework with Sr cations located in one-dimensional channels. There are two distinct Th environments, bicapped trigonal prismatic and distorted monocapped octahedral. There are no Se-Se bonds and so formal oxidation states of Sr(2+), Th(4+), and Se(2)(-) may be assigned.

Journal Article↗
PubMed1988

Drug-induced and toxic granulomatous hepatitis.

The ability to induce granulomatous hepatitis has been attributed to numerous drugs; some sixty causative drugs have been culled from the literature for this review. Additionally, granulomas or granulomatoid lesions have resulted from occupational exposure to toxic substances (e.g. silica, copper sulphate, beryllium compounds), and particulate material from various therapeutic or diagnostic procedures (e.g. reactions to starch, talc, suture material, polyvinyl pyrrolidone, silicone, barium sulphate, thorium dioxide) or from intravenous drug abuse (e.g. talc). Clinically, patients with drug-induced or toxic granulomatous hepatitis may be asymptomatic. More frequently, the presentation is that of an acute febrile illness, with or without a rash and eosinophilia, followed by jaundice and biochemical evidence of hepatic dysfunction. The diagnosis of drug-induced granulomatous hepatitis is based largely on ruling out other aetiologies. Liver biopsy plays a key role in diagnosis. Recovery is the rule following withdrawal of the drug. Morphologically, drug-induced granulomas may be impossible to distinguish from those due to other causes. Associated lesions suggesting a drug aetiology include significant tissue eosinophilia, unicellular hepatocytic degeneration and necrosis, cholestasis and acute cholangitis or vasculitis. Special stains, polarizing and phase contrast microscopy, transmission and scanning electron microscopy and energy dispersive X-ray microanalysis all play a role in the aetiologic diagnosis of some types of granulomas.

Chemical and Drug Induced Liver Injury↗
PubMed2005

New hydrothermal synthesis and structure of Th2(PO4)2(HPO4).H2O: the first structurally characterized thorium Hydrogenphosphate.

Th(2)(PO(4))(2)(HPO(4)).H(2)O was synthesized under wet hydrothermal conditions starting from a mixture of H(3)PO(3) and Th(NO(3))(4).5H(2)O. The crystal structure was solved by powder X-ray diffraction data. The unit cell parameters are a = 6.7023(8) Angstroms, b = 7.0150(8) Angstroms, c = 11.184(1) Angstroms, beta = 107.242(4) degrees, space group P2(1), and Z = 2. The structure consists of layers of both thorium atoms and PO(4) groups, alternating with a layer formed by HPO(4) entities and water molecules. By thermal treatment, this compound turns into Th(4)(PO(4))(4)P(2)O(7), a ceramic already described in the field of the immobilization of tetravalent actinides.

Journal Article↗
PubMed1995

Physiological and toxicological changes in the skin resulting from the action and interaction of metal ions.

The human environment contains more than 50 metal or metalloid elements. At least 15 are recognized as trace elements, with zinc, calcium, copper, magnesium, and iron having specific roles in skin morphogenesis and function. The present review focuses on the presumed role of metal ions in the skin, their competition for carrier proteins, and membrane receptors. Evidence presented shows that the balance of trace metal ions is critical for normal skin and repair mechanisms following injury. Xenobiotic ions can impair this balance, leading to pathological change. The skin acts as an organ of elimination of excess trace metals and xenobiotic ions from the body, but mechanisms of voidance vary for different metals. Metal ions are an important cause of allergies, and evidence is presented to show that the majority of metals or metal compounds can induce allergic changes. Except for chromium and nickel, which are among the most common human allergens, animal models have provided little information. At least cadmium, thorium, lead, chromium, nickel, beryllium, and arsenic and proven or putative carcinogens in animals or humans on the basis of cytological or epidemiological evidence. However, only arsenic exhibits a clear predilection for the skin. Other metals such as gold can induce subcutaneous sarcoma following injection, but the relevance of this observation in terms of human occupational risk is discounted.

Animals↗
PubMed2005

Synthesis and characterization of two quaternary thorium chalcophosphates: Cs4Th2P6S18 and Rb7Th2P6Se21.

Two new thorium chalcophosphates have been synthesized by the reactive flux method and characterized by single-crystal X-ray diffraction, diffuse reflectance, and Raman spectroscopy: Cs4Th2P6S18 (I); Rb7Th2P6Se21 (II). Compound I crystallizes as colorless blocks in the triclinic space group P1 (No. 2) with a = 12.303(4) A, b = 12.471(4) A, c = 12.541(4) A, alpha = 114.607(8) degrees, beta = 102.547(6) degrees, gamma = 99.889(7) degrees, and Z = 2. The structure consists of (Th2P6S18)(4-) layers separated by layers of cesium cations and only contains the (P2S6)(4-) building block. Compound II crystallizes as red blocks in the triclinic space group P1 (No. 2) with a = 11.531(3) A, b = 12.359(4) A, c = 16.161(5) A, alpha = 87.289(6) degrees, beta = 75.903(6) degrees, gamma = 88.041(6) degrees, and Z = 2. The structure consists of linear chains of (Th2P6Se21)(7-) separated by rubidium cations. Compound II contains both the (PSe4)(3-) and (P2Se6)(4-) building blocks. Both structures may be derived from two known rare earth structures where a rare earth site is replaced by an alkali or actinide metal to form these novel structures. Optical band gap measurements show that compound I has a band gap of 2.8 eV and compound II has a band gap of 2.0 eV. Solid-state Raman spectroscopy of compound I shows the vibrations expected for the (P2S6)(4-) unit. Raman spectroscopy of compound II shows the vibrations expected for both (PSe4)(3-) and (P2Se6)(4-) units. Our work shows the remarkable diversity of the actinide chalcophosphate system and demonstrates the phase space is still ripe to discover new structures.

Journal Article↗
PubMed2000

Synthesis and structural characterization of quaternary thorium selenophosphates: A2ThP3Se9 (A = K, Rb) and Cs4Th2P5Se17.

Single crystals of A2ThP3Se9 (A = K (I), Rb (II)) and Cs4Th2PsSe17 (III) form from the reaction of Th and P in a molten A2Se3/Se (A = K, Rb, Cs) flux at 750 degrees C for 100 h. Compound I crystallizes in the triclinic space group P1 (No. 2) with unit cell parameters a = 10.4582(5) A, b = 16.5384(8) A, c = 10.2245(5) A, alpha = 107.637(1); beta = 91.652(1); gamma = 90.343(1) degrees, and Z = 2. Compound II crystallizes in the triclinic space group P1 (No. 2) with the unit cell parameters a = 10.5369(5) A, b = 16.6914(8) A, c = 10.2864(5) A, alpha = 107.614(1) degrees, beta = 92.059(1) degrees, gamma = 90.409(1) degrees, and Z = 2. These structures consist of infinite chains of corner-sharing [Th2Se14] units linked by (P2Se6)4- anions in two directions to form a ribbonlike structure along the [100] direction. Compounds I and II are isostructural with the previously reported K2UP3Se9. Compound III crystallizes in the monoclinic space group P2(1)/c (No. 14) with unit cell parameters a = 10.238(1) A, b = 32.182(2) A, c = 10.749(1) A; beta = 95.832(1) degrees, and Z = 4. Cs4Th2P5Se17 consists of infinite chains of corner-sharing, polyhedral [Th2Se13] units that are also linked by (P2Se6)4- anions in the [100] and [010] directions to form a layered structure. The structure of III features an (Se2)2- anion that is bound eta 2 to Th(2) and eta 1 to Th(1). This anion influences the coordination sphere of the 9-coordinate Th(2) atom such that it is best described as bicapped trigonal prismatic where the eta 2-bound anion occupies one coordination site. The composition of III may be formulated as Cs4Th2(P2Se6)5/2(Se2) due to the presence of the (Se2)2- unit. Raman spectra for these compounds and their interpretation are reported.

Journal Article↗
PubMed2004

Radioactivity distribution in some Permian sediments from the Iratí and Corumbataí Formations of the Paraná Basin, Southeastern Brazil.

In the city of Limeira, southeastern Brazil, an important exposure of Permian sediments of the Paraná basin was revealed by an open pit mine that exploits limestone for production of soil correction compounds and raw materials for the ceramic industry. The radioactivity of these sediments was investigated in some detail and the results provided a general view of the vertical distributions of uranium, thorium and potassium concentrations and of the element ratios U/K, U/Th and Th/K. In general, the concentrations of the main natural radioactive elements are low, with uranium being enriched in some limestone and shale levels. In addition the results showed that the 238U series is in radioactive disequilibrium in many of the analyzed samples. Although the origin of the observed disequilibrium has not been investigated, the results suggest that it is due to weathering processes and water interaction with the rock matrix.

Brazil↗
PubMed1994

Effects of preconceptional irradiation on mortality and cancer incidence in the offspring of patients given injections of Thorotrast.

BACKGROUND: Findings from a British case-control study suggest that a preconceptional paternal external radiation dose of more than 100 mSv (10 rem) is significantly related to risk for leukemia and non-Hodgkin's lymphoma in offspring. The suggestion, however, has not been supported by experimental or other epidemiologic studies. PURPOSE: The purpose of this study was to investigate if preconceptional irradiation of males and females from internally deposited radionuclides affects mortality and risk of developing cancer in their offspring. METHODS: The offspring of 260 females (n = 143) and 320 males (n = 226) who lived longer than 1 year after receiving Thorotrast (a compound no longer in use) for cerebral arteriography were studied for mortality rate and the risk for developing cancer. Thorotrast was used as a contrast medium containing a 20% colloidal solution of thorium dioxide-Th 232, an alpha particle-emitting radionuclide, which is retained lifelong in nearly all organs. The offspring of the exposed patients were identified by manual linkage with the municipal population registers and followed-up for vital status by computerized linkage with the Danish National Central Population Registry and for incidence of cancer by computerized linkage with the Danish National Cancer Registry. The standardized mortality/morbidity ratios (SMRs) for death and for site-specific incidence of cancer in the offspring were calculated as ratios of the observed rates in the study population to the expected rates in the general population. RESULTS: After a median follow-up of 40 years, four cases of cancer (breast [one], uterine cervix [one], melanoma of skin [one], and retinoblastoma [one]) versus 2.9 cases expected, developed among 143 children born to mothers who received injections of Thorotrast (SMR = 1.4; 95% confidence interval [CI] = 0.4-3.5), while six cases of cancer (one case each of cancer of lung, testis, thyroid, and Hodgkin's lymphoma and two cases of melanoma of skin), versus 4.5 expected, occurred among 226 children of exposed fathers (SMR = 1.3; 95% CI = 0.5-2.9). No case of leukemia or non-Hodgkin's lymphoma occurred in any of the offspring studied. Mortality was lower than expected both for children of exposed mothers (SMR = 0.7; 95% CI = 0.3-1.5) and of exposed fathers (SMR = 0.5; 95% CI = 0.2-1.0). CONCLUSIONS: This study does not support the previously proposed association between parental exposure to radiation and the risk of childhood leukemia and lymphoma. Furthermore, since mortality from all causes was not increased in any offspring, our results do not support the belief that preconceptional parental low-dose exposure to alpha radiation increases the incidence of cancer or mortality in the offspring.

Adolescent↗
PubMed2004

Preliminary results on the immobilisation of radionuclides from waters with specific adsorbers based on phosphate salts.

The present paper is focused on the ability of aluminium phosphate (ALPC), magnesium ammonium phosphate (MGPC), magnesium hydrogen phosphate (MGHPC), and calcium hydrogenphosphate (CAHPC), adsorbed onto charcoal, to immobilise actinides by adsorption from natural waters. The objective of this process is to evaluate the environmental pollution due to the actinides. Europium, thorium, protactinium, neptunyl, and uranyl ions were chosen to simulate actinides in the +3, +4, +5 and +6 oxidation state. The adsorbers were tested using natural waters samples. The adsorption trends and capacities were analysed. ALPC and MGPC exhibited a similar behaviour and adsorbed demonstrating that the +5, +4 and +3 actinide ions can be easily immobilised from natural waters and may be successfully used at pH 7-8. MGHPC may be used at a higher pH, whereas CAHPC is effective in the whole pH range. In all cases, thorium, protactinium and europium were strongly

Actinoid Series Elements↗
PubMed2006

Probing actinide electronic structure using fluorescence and multi-photon ionization spectroscopy.

The role of the 5f orbitals in actinide bond formation is one of the central issues of actinide chemistry. This question can be explored using relativistic quantum chemistry calculations, but the theoretical methods must be validated using definitive experimental data. For simple ionic compounds such as actinide oxides and halides, the electronic structure can be examined using electronic and photoelectron spectroscopy of gas phase molecules. The present article surveys recent spectroscopic and theoretical studies of the oxides of thorium and uranium. The results show that the 5f-like states are spectators and that the complex patterns of low-lying electronic states for these molecules can be understood in terms of a semi-empirical ligand field model. Comparisons with recent high-level theoretical calculations are presented and discussed.

Journal Article↗