SECD Research Articles

Trace metals in striped dolphins (Stenella coeruleoalba) stranded along the Murcia coastline, Mediterranean Sea, during the period 2009–2015.

Mercury (Hg), cadmium (Cd), lead (Pb), selenium (Se) and arsenic (As) concentrations in internal tissues of 72 striped dolphins (Stenella coeruleoalba) from Murcia Region (Mediterranean coastline) have been investigated for the first time. Hg showed the highest concentration, followed by Se, Cd, As and Pb. In general, the levels of metal found in this study were similar to those described in similar studies in the Mediterranean Sea. However, in some adult specimens, Hg liver concentrations were related with toxic effects in cetacean. A significant correlation was observed with age, likewise between Se and Hg and Cd in tissues, which agree with detoxify effect attributed to Se through inert complex formation. Molar ratio Hg:Se in liver was close to 1:1 in some specimens, which would indicate overload of the Hg-Se detoxify function and compromised health. These results could contribute to a better knowledge of the distribution of these persistent pollutants in the Mediterranean Sea.

Plasma Selenium and Cadmium Levels in Patients with Chronic Otitis Media in a Turkish Population and Their Relation to Inflammation Markers.

Chronic otitis media (COM) is a multifactorial process, for which a clear etiology has not yet been established. The aims of the present study were to evaluate selenium (Se) and cadmium (Cd) levels in patients with COM and to analyze the correlation between Se and Cd with inflammation markers. The study population consisted of 88 participants: 45 healthy controls (group 1) and 43 patients with COM (group 2). Demographic data, Se, Cd, C-reactive protein (CRP), and white blood cell count (WBC) levels were all recorded. Se and Cd measurements were performed in a graphite furnace atomic absorption spectrophotometer (Perkin Elmer Analyst 800) using Zeeman background correction. The Se and Cd levels were compared between the groups and the correlation between Se and Cd with inflammation markers was analyzed. No statistically significant difference was determined between the groups in terms of demographic data (p > 0.05). CRP and WBC levels were significantly higher in group 2 than in group 1 (p < 0.05). Se levels were significantly lower in group 2 than in group 1, at 23.40 ± 12.08μg/L vs. 37.31 ± 22.44μg/L (p < 0.05). Cd levels were significantly higher in group 2 than in group 1, at 1.79 ± 1.63μg/L vs. 0.68 ± 0.45μg/L (p < 0.05). When all the cases were evaluated together, a statistically significant negative correlation was determined between Se and CRP (r = - 0.239, p = 0.013) and a positive correlation between Cd and CRP (r = 0.266, p = 0.006), WBC (r = 0.258, p = 0.008). Our results could propose that Se deficiency and Cd excess could play a crucial and additive role in the etiopathogenesis of COM. However, further investigations with larger numbers of patients are warranted to determine the exact role of these elements.

Effect of selenium on the uptake kinetics and accumulation of and oxidative stress induced by cadmium in Brassica chinensis

Pak choi can readily accumulate cadmium (Cd) into its edible parts; this can pose a threat to human health. Although not essential for higher plants, selenium (Se) can be favorable for plant growth and antioxidative defense under heavy metal stress conditions. A pak choi hydroponic experiment was conducted to investigate the effect of two forms of Se on the Cd uptake kinetics and accumulation and oxidative stress. The results showed that selenite and selenate remarkably enhanced Cd uptake kinetics in pak choi. The maximum Cd uptake rate increased by more than 100% after treatment with 5 µM of selenite and selenate, and it further increased after treatment with 20 µM of both Se forms. The effects of Se on Cd content depended on the Se form, exposure time, and Cd dosage. Selenite reduced the Cd content in shoots by 41% after 3 days of treatment with 10 µM Cd, whereas selenate increased this rate by 89%. Both forms of Se decreased Cd content in the shoots by 40% after 7 days of treatment with 10 µM Cd, but they increased the Cd content by approximately 30% after treatment with 50 µM Cd. Se enhanced Cd-induced oxidative stress in pak choi. Malondialdehyde (MDA) generation was promoted by more than 33% by selenite and selenate treatments in combination with 10 µM Cd, and it was further enhanced by 106% and 185% at 50 µM Cd, respectively. Selenite also increased the H2O2 content at both Cd doses, but selenate did not have significant effects on H2O2 production. The effects of Se on antioxidative enzyme activity also depended on the dose of Cd. Selenite and selenate inhibited catalase activity by 11% and 29%, respectively, at 10 µM Cd, and by 13% and 42%, respectively, at 50 µM Cd. Moreover, both forms of Se increased superoxide dismutase activity after treatment with 10 µM Cd but inhibited its activity at 50 µM Cd. Therefore, Se exhibits dual effects on Cd accumulation and oxidative stress in pak choi and might cause further stress when combined with higher doses of Cd.

Inhibitory effects of selenium on cadmium-induced cytotoxicity in PC12 cells via regulating oxidative stress and apoptosis

Purpose of this study is to investigate mechanism/s of cyto-protection by selenium (Na2SeO3; Se4+) against cadmium (CdCl2; Cd2+)-induced cytotoxicity using PC12 cells. In addition, Se (5, 10, 20 and 40 μM) and Cd (2.5, 5 and 10 μM)-induced cytotoxicity is determined. Cytotoxicity assays and western blot analyses confirmed that Se (≥10 μM) promotes autophagic cell death via inhibition of mTOR activation and p62 accumulation due to increase of cellular oxidative stress. On the other hand, co-presence of non-toxic Se (5 μM) and toxic Cd (5 μM) showed to increase cell viability, glutathione and glutathione peroxidase 1 (GPx1) levels, and to decrease DNA fragmentation and lactate dehydrogenase (LDH) activity compared to Cd-treated (5 μM) cells alone. Furthermore, western blot analyses of cytochrome c and ERK1 indicated that Cd-induced apoptotic cell death in PC12 cells. However, the co-exposure of Se with Cd significantly decreases the release of cytochrome c into cytosol from mitochondria, and up-regulates ERK1 protein to inhibit Cd-induced apoptosis. In conclusion, Se (≥10 μM) possess cytotoxicity in PC12 cells; however, co-presence of Se (5 μM) with Cd (5 μM) protects against Cd-induced apoptosis in PC12 cells due to inhibition of Cd-induced oxidative stress and subsequently suppression of mitochondrial apoptosis pathway.

Zn–Se–Cd–S Interlayer Formation at the CdS/Cu2ZnSnSe4 Thin-Film Solar Cell Interface

The chemical structure of the CdS/Cu2ZnSnSe4 (CZTSe) interface was studied by a combination of electron and X-ray spectroscopies with varying surface sensitivity. We find the CdS chemical bath deposition causes a “redistribution” of elements in the proximity of the CdS/CZTSe interface. In detail, our data suggest that Zn and Se from the Zn-terminated CZTSe absorber and Cd and S from the buffer layer form a Zn–Se–Cd–S interlayer. We find direct indications for the presence of Cd–S, Cd–Se, and Cd–Se–Zn bonds at the buffer/absorber interface. Thus, we propose the formation of a mixed Cd(S,Se)–(Cd,Zn)Se interlayer. We suggest the underlying chemical mechanism is an ion exchange mediated by the amine complexes present in the chemical bath.

Dielectric relaxation and AC conductivity studies of Se90Cd10−xInx glassy alloys

Chalcogenide glassy alloys of Se90Cd10−xInx (x = 2, 4, 6, 8) are synthesized by melt quench technique. The prepared glassy alloys have been characterized by techniques such as differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and energy dispersive X-ray (EDAX). Dielectric properties of Se90Cd10−xInx (x = 2, 4, 6, 8) chalcogenide glassy system have been studied using impedance spectroscopic technique in the frequency range 42 Hz to 5 MHz at room temperature. It is found that the dielectric constants ɛ′, dielectric loss factor ɛ″ and loss angle Tan δ depend on frequency. ɛ′, ɛ″ and loss angle Tan δ are found to be decreasing with the In content in Se90Cd10−xInx glassy system. AC conductivity of the prepared sample has also been studied. It is found that AC conductivity increases with frequency where as it has decreasing trend with increasing In content in Se–Cd matrix. The semicircles observed in the Cole–Cole plots indicate a single relaxation process.

Serum Heavy Metal Levels in Patients with Ineffective Erythropoiesis and the Effect of Chelation on Heavy Metal Levels

Aim: In disorders with ineffective erythropoiesis like thalassemia major (TM) iron absorption from gastrointestinal tract increases regardless of iron store. Iron is taken into enterocytes at duodenum via apical divalent metallo protein 1 (DMT-1) protein. Besides iron DMT-1 also transports other divalent metals like cadmium (Cd) , cobalt (Co), copper (Cu), lead (Pb), manganese, nickel, and zinc (Zn). In our study we hypothesized that absorption of heavy metals via DMT-1 protein may be elevated in particularly TM and other disorders with ineffective erythropoiesis, and we aimed to investigate blood heavy metal levels in these patients and compare with control group.Methods: Study was performed between December 2014 and April 2015 in Hacettepe University Children Hospital Pediatric Hematology Clinic and Gulhane Military Medical Academy Pediatric Hematology Clinic. Blood samples were taken from patients with TM, thalassemia intermedia (TI), congenital dyserythropoietic anemia (CDA), and age and sex matched healthy control group. Heavy metal exposure was searched via questionnaire for each participant. Serum heavy metals including aluminium (Al), Cd, Co, crom (Cr), Cu, Pb, selenyum (Se), and Zn were measured.Results: Blood samples were obtained from 51 patients with TM, 8 with TI, 9 with CDA, and control group included 65 healthy volunteers. General characteristics of patients and control group were showed on Table 1. There wasn't statistical difference between patients and control group in terms of age and heavy metal exposure. Plasma or serum heavy metal levels of patients and control group were shown in Table 2. Patients with TM were found to have lower Al, Pb, Se, and Zn, and higher Cd levels compared to control group. In patients with TM, Cd level was higher than control group, however median value of Cd was still in normal range. In TI group only Se level was lower (p; 0.003), in CDA group both Se (p; 0.008) and Zn (p; 0.02) levels were lower compared to control group. When we looked for patients with TM, TI, and CDA who were treated with deferasirox; Al, Pb, Se, and Zn levels were lower, and Cd level was higher than control group.Discussion: Opposite to our hypothesis Al, Pb, Se. and Zn levels were lower in TM group and in group of patients who were on deferasirox. Se and Zn levels in patients with TM have been studied before but contradictory results have been reported. Generally they were reported to be lower in patients with TM. These results have been explained with micronutrient deficiency, and chelator treatment. Deferasirox has been reported to bind to Al and Zn, as well. The lower Al and Zn levels in our study may be explained with deferasirox therapy. Deferasirox may also have capacity to bind Pb, related to the lower levels found in our study in deferasirox group. In addition to iron chelation, chelator treatment with deferasirox might have protective effects in patients with ineffective erythtopoiesis against heavy metal toxicity.Table 1General characteristics of patient and control groupsTMTICDAControlNumber518965Age* (year)20.2 (4.5-39)8.8 (3.4-37)9 (2.5-14.6)16.8 (3-39)Male/female23/283/56/333/32Heavy metal exposureYesNo213062813134Chelator usageNoDeferasiroxDeferoxamineDeferoxamine+ deferriprone0464126004500TM: thalassemia major, TI: thalassemia intermedia, CDA: congenital dyserythropoietic anemia*Median and rangeTable 2Heavy metal levels in patient and control groupsTMTICDAControlpaAluminium (mcg/L) (0-50)27.,6 (10.1-82.1)*50.1 (18.2-91.3)41.1 (11.3-48.5)43.8 (2.4-175.6)0.01Copper (mcg/dL) (70-150)71.7 (22.3-175.5)90.5 (27.9-165.2)59.9 (35.1-110.3)78.5 (20.5-189)0.1Zinc (mcg/dL) (70-120)56 (21.8-126.2)63.8 (34.4-130.2)59.3 (23.6-76.9)70.8 (36-166.8)0.001Cadmium (mcg/L) (0.3-1.2)0.75 (0.34-2.82)0.77 (0.36-1.37)0.59 (0.38-0.78)0.58 (0.23-3.54)0.002Cobalt (mcg/L) (0.5-3.9)0 (0-6.73)0.19 (0-1.94)0.08 (0-2.49)0.39 (0-6.59)0.23Crom (mcg/L) (2.8-45)45.08 (39.4-63.8)45.1 (41.7-47.5)45.7 (35.5-53.7)46.9 (28.5-96.1)0.49Lead (mcg/L) (0-150)3.83 (0-22.7)6.71 (0-11.1)5.18 (0-16.3)9.31 (0-45.2)0.01Selenium (mcg/L) (0-150)24.6 (11.8-42.5)21.7 (8.7-35.3)25.6 (20.3-31.8)33.,3 (15.1-71.5)<0.001TM: thalassemia major, TI: thalassemia intermedia, CDA: congenital dyserythropoietic anemia* Median and rangeaComparison of control group and patients with thalassemia major DisclosuresNo relevant conflicts of interest to declare.

The Gounkoto Au deposit, West Africa: Constraints on ore genesis and volatile sources from petrological, fluid inclusion and stable isotope data

The Loulo–Gounkoto complex in the Kédougou–Kéniéba Inlier hosts three multi-million ounce orogenic gold deposits, situated along the Senegal–Mali Shear Zone. This west Malian gold belt represents the largest West African orogenic gold district outside Ghana. The Gounkoto deposit is hosted to the south of the Gara and Yalea gold mines in the Kofi Series metasedimentary rocks. The ore body is structurally controlled and is characterised by sodic and phyllic alteration, As- and Fe-rich ore assemblages, with abundant magnetite, and overall enrichment in Fe–As–Cu–Au–Ag–W–Ni–Co–REE+minor Te–Pb–Se–Cd. Fluid inclusion analysis indicates that the deposit formed at P–T conditions of approximately 1.4kbar and 340°C and that two end member fluids were involved in mineralisation: (1) a moderate temperature (315–340°C), low salinity (<10wt.% NaCl equiv.), low density (≤1g·cm−3), H2O–CO2–NaCl–H2S±N2–CH4 fluid; (2) a high temperature (up to 445°C), hypersaline (~40wt.% NaCl equiv.), high density (~1.3g·cm−3), H2O–CO2–NaCl±FeCl2 fluid. Partial mixing of these fluids within the Jog Zone at Gounkoto enhanced phase separation in the aqueo-carbonic fluid and acted as a precipitation mechanism for Au. These findings demonstrate the widespread, if heterogeneously distributed, nature of fluid mixing as an ore forming process in the Loulo–Gounkoto complex, operating over at least a 30km strike length of the shear zone. Stable isotope analyses of ore components at Gounkoto indicate a dominant metamorphic source for H2O, H2S and CO2, and by extension Au. It thus can be reasoned that both the aqueo-carbonic and the hypersaline fluid at Gounkoto are of metamorphic origin and that the high levels of salinity in the brine are likely derived from evaporite dissolution.

Photogenerated excitons in plain core CdSe nanocrystals with unity radiative decay in single channel: the effects of surface and ligands.

A systematic and reproducible method was developed to study the decay dynamics of an exciton, a photogenerated electron-hole pair, in semiconductor nanocrystals in solution. Results revealed that the excitons in plain core CdSe nanocrystals in either zinc-blende or wurtzite or mixed lattice structures could be reproducibly prepared to decay radiatively in unity quantum yield and in single channel. The single-channel lifetime was found to increase monotonically by increasing size of the CdSe nanocrystals, with zinc-blende ones increasing in a relatively slow pace. Surface inorganic stoichiometry was found to be a sensitive parameter to affect the exciton decay dynamics for all crystal structures with different sizes. Excess Se (Cd) sites on the surface were found to induce short (long) lifetime channels for the excitons. Both types of traps reduced the quantum yield of the radiative decay of the excitons, and the hole traps associated with Se sites were nearly not emissive. With optimal surface inorganic stoichiometry, primary amines were identified as "ideal" organic ligands for CdSe core nanocrystals to achieve unity radiative decay of excitons in single channel in comparison to other types of neutral ligands commonly applied in the field.

Effect of Selenium Supplementation on Serum Amylase, Lactate Dehydrogenase and Alkaline Phosphatase Activities in Rats Exposed to Cadmium or Lead

Abstract The purpose of the study was to assess the effect of selenium supplementation on serum amylase, lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) activities in rats, during subacute exposure to toxic doses of cadmium or lead through the drinking water. The experimental groups (n=6) were: Control, Se (Se+4: 0,2 mg/l), Cd (Cd+2: 150 mg/l), Pb (Pb+2: 300 mg/l), Cd+Se (Cd+2: 150 mg/l; Se+4: 0,2 mg/l) and Pb+Se (Pb+2: 300 mg/l; Se+4: 0,2 mg/l). The animals were sacrificed after 56 days. Amylase, LDH and ALP activities were determined from serum. Se and Pb treatments caused an increase in amylase and LDH activities, when compared to Control group while Cd caused an increase in amylase activity and a decrease in LDH and ALP activities. Cd+Se caused a decrease in amylase activity and an increase in LDH activity, when compared to Cd. Pb+Se caused a decrease in amylase activity in comparison to lead. Selenium supplementation alleviated cadmium or lead induced changes in serum amylase activity. Selenium, coadministered with cadmium, caused a marked increase in serum LDH activity, when compared to cadmium alone or Control group while practically it had no effect on lead induced changes in LDH activity. Cadmium and lead induced disturbances in serum ALP activity were not influenced by selenium supplementation.

Distribution of Co, Cu, Fe, Mn, Se, Zn, and Cd among cytosolic proteins of different molecular masses in gills of European chub (Squalius cephalus L.).

The distribution of essential elements Co, Cu, Fe, Mn, Se, and Zn, and nonessential element Cd among cytosolic proteins of different molecular masses in the gills of European chub (Squalius cephalus) sampled in the moderately contaminated Sutla River in September of 2009, was studied after the protein separation by size exclusion high-performance liquid chromatography (SEC-HPLC), and the metal determination in the obtained fractions by high-resolution inductively coupled plasma mass spectrometry (HR ICP-MS). The aims of the study were to characterize the distribution profiles of metals within different protein categories in gills in the conditions of low metal exposure in the river water, and to compare them with the previously published hepatic profiles. The distribution profiles of analyzed metals were mainly characterized with several peaks. However, some observations could be emphasized: both Cu and Cd were eluted near metallothionein elution time; elution time of one of Co peaks could be associated with Co-containing compound cobalamin; increasing cytosolic Fe concentrations resulted in possible Fe binding to storage protein ferritin; both Mn and Zn had poorly resolved peaks covering wide ranges of molecular masses and indicating their binding to various proteins; both Zn and Se increased in protein fractions of molecular masses <5 kDa following their concentration increase in the gill cytosol; expected clear metallothionein peak was not observed for Zn. Comparison of gill profiles with previously published hepatic profiles revealed similar and in case of some elements (e.g., Co, Fe, Mn, and Se) almost identical distributions in both organs regarding elution times. On the contrary, heights of obtained peaks were different, indicating possible metal binding to the same proteins in the gills and liver, but in different proportions. The results obtained in this study can be used as a basis for comparison in monitoring studies, for identification of changes that would occur after exposure of chub to increased metal concentrations.

An integrated approach to environmental quality assessment in a coastal setting in Campania (Southern Italy)

The coastal region of Southern Italy’s Caserta province, known as the LitoraleDomitio (Domitia coast) has been subjected to increasing pressure from unsustainably fast economic and urban growth in the last century, that resulted in a induced serious land degradation. To obtain a comprehensive picture of the ecological status of the Domitia coastal zone (Campania, Southern Italy), a holistic methodology has been applied. Sedimentological, geochemical, and biological analyses of the surface sediments and water samples were performed along the submerged beach. The data were integrated using a geographical information system, together with information on past and present land use and human activities along the coast and in inland regions. Heavy metal concentrations in sediments plus As and Se (Cd, Co, Cr, Cu, Hg, Ni, Pb, V, Zn) and their enrichment factors, which are important for identifying polluted areas in countries like Italy (where environmental legislation has not yet established intervention limits), indicate excesses Cd, Cr, Pb, and V of probable anthropogenic origin. A microbiological contamination of marine waters has been detected by the Regional Environmental Protection Agency of Campania. The Bacteriological Quality Index map shows that bathing areas must be classified as “contaminated” and “highly contaminated”. High levels of chemical and biological contamination are particularly common in both bathing seawater and sediments along the coastal zone south of the Volturno River, where the existing wastewater treatment plant is not properly working, to date. Factory farming, which is widespread in the area, is likely to be an additional important source of contamination. In accordance with these conclusions, analyses of the benthic diatom community revealed dominance of eutrophic species.

Glass transition kinetics and crystallization mechanism in Se90Cd8Bi2 and Se90Cd6Bi4 chalcogenide glasses

Differential scanning calorimeter (DSC), under non-isothermal condition, was used to study the glass transition kinetics and the crystallization mechanism of Se90Cd8Bi2 and Se90Cd6Bi4 glassy alloys. Two approaches, namely Moynihan and Kissinger, were used to calculate the relaxation activation energy (Et) from the dependence of the glass transition temperature (Tg) on the heating rate (β). Results reveal that Et decreases with an increase in Bi content which indicates that thermal stability is improved. This is attributed to the formation of Se–Bi bonds which are stronger than Se–Cd bonds and heavily cross-link the structure. In addition, the kinetic analysis of the crystallization peaks was performed using Ozawa, Kissinger, Takhor and Augis–Bennett relations. The values of the crystallization activation energy (Ec) and Avrami exponent (n) of the two alloys were evaluated. The obtained values of Ec, calculated from the above mentioned relations, were found to be in good agreement while the average calculated values of Avrami exponent (n) are (2.3±0.1) for Se90Cd8Bi2 and (1.7±0.1) for Se90Cd6Bi4 which indicating that the crystal growth in the two alloys occurs in one dimension.

Effects of cadmium chloride and sodium selenite alone or in combination on the liver of male Sprague-Dawley rats assessed by different assays.

This study assessed the impact of either cadmium chloride (Cd) or sodium selenite (Se) alone or in combination on male Sprague-Dawley rats. For this purpose, body and liver weights, comet and TUNEL assays, histological analysis and levels of lipid peroxidation and antioxidants in liver were determined in four groups of male Sprague-Dawley rats. The rats were given subcutaneous doses of 1 mg/kg body weight (BW) of either normal saline (control=Ct) or Cd or Se or Cd plus Se (Cd+Se) on alternate days for 4 weeks. The Cd group showed increased DNA damage, apoptosis and hepatic levels of lipid peroxidation and altered histology. Conversely, the antioxidant levels in this group were decreased as compared with the control group. The Se group also showed DNA damage, apoptosis and altered histology and reduced catalase activity, but it was less severe than the Cd group. In the Cd+Se group, ameliorating effects of Se on Cd-induced changes were observed. While the Se was able to curtail the toxic effect of Cd, the Cd or Se alone were genotoxic and cytotoxic for rats receiving a high pharmacological but non-fatal dose of 1 mg/kg BW.

Refinement of the crystal structure of dipotassium tricadmium(II) tetraselenide, K2Cd3Se4

Cd3K2Se4, orthorhombic, Pnma (no. 62), a = 14.312(4) A, b = 10.604(3) A, c = 6.839(2) A, V = 1037.9 A, Z = 4, Rgt(F) = 0.027, wRref(F) = 0.065, T = 290 K. Source of material CdCl2 (0.020 g, 0.11mmol) andK2Se2 (0.078 g, 0.33mmol)were charged to a Pyrex tube with diameter of 9 mm under an argon atmosphere, and about 0.5 ml ethylenediamine was added as a solvent. While the solvent was being frozen, the Pyrex tube was evacuated (about 2.0 × 10 torr) and sealed with the use of a flame. The sealed tube was placed in a furnace and heated at 160 °C for 24 h, then cooled to room temperature. Yellow crystals were isolated and washed with diethyl ether several times (36 % yield, based on CdCl2 used). The compound is insoluble in water and common organic solvents. Discussion Ternary low-dimensional cadmium chalcogenides, A2Cd3Q4 (A = alkali metal; Q = S, Se, Te) were explored in particular to achieve the dimensional reduction in II-VI materials [1-2]. Dimensional reduction of CdQ by the incorporation of A2Q resembles size reduction of CdQ particles into the nanometer range [2]. Nanometer-sized CdQ materials have attracted extensive research efforts last two decades and are still garnering a lot of attention [3-5]. The title compound is the first example of A/Cd/Q (A = alkali metal; Q = S, Se, Te) ternary compounds to be prepared by a hydro (or solvo) thermal method. Until now, only the lattice parameters for K2Cd3Se4 were reported, no complete structure determination was made [1]. The title crystal structure is composed of two-dimensional anionic layers (Cd3Se4)n and charge-balancing cationsK, representing the same structure as the other analogues of A2Cd3Q4 (A = K, Q = S, Te; A = Rb, Q = S, Se) [1]. Other structurally characterized A2Cd3Q4 compounds are Rb2Cd3Te4 and Cs2Cd3Te4, which crystallize in K2Zn3O4 type and Cs2Zn3S4 type, respectively [6]. The (Cd3Se4)n layer spreads out along the crystallographic b and c axes, with the repeating unit of a Cd3Se4 cluster (figure, top). The Cd3Se4 cluster is geometrically shaped as a truncated cube with one corner missing and consists of three Cd(II)metal ions and four Semonoselenide ligands. In the truncated cube cluster, one Se atom could be regarded to be sitting on the apex and coordinating to the threeCdmetal atoms in the puckered 6-member ring Cd3Se3. Three-coordinated Cd atoms and two-coordinated Se atoms in the Cd3Se4 cluster are connected to Se andCd atoms of adjacent clusters to form a layered structure (figure, bottom). As a result, all Cd atoms are tetrahedrally coordinated and all Se atoms are triply coordinated. Tetrahedral coordination of Cd atoms is distorted as the ∠Se–Cd–Se angles are ranging from 95.8° to 140.3°, and trigonal pyramidal coordination of Se atoms is encountered with the ∠Cd–Se–Cd angles ranging from 73.6° to 108.1°. Z. Kristallogr. NCS 226 (2011) 157-158 / DOI 10.1524/ncrs.2011.0071 157 © by Oldenbourg Wissenschaftsverlag, Munchen Crystal: yellow plate, size 0.04 × 0.10 × 0.48 mm Wavelength: Mo K* radiation (0.7107 A) -: 208.42 cm−1 Diffractometer, scan mode: MacScience MXC3, '% 2!max: 55° N(hkl)measured, N(hkl)unique: 1207, 1207 Criterion for Iobs, N(hkl)gt: Iobs > 2 σ(Iobs), 1067 N(param)refined: 50 Programs: SHELXS-97, SHELXL-97 [7], ORTEP-3 [8] Table 1. Data collection and handling.

Thermal stability and crystallization kinetics of Ge–Se–Cd glasses

The effect is reported of varying cadmium concentration on the glass transition, thermal stability and crystallization kinetics of Ge20Se80− x Cd x (x = 2.5, 5, 7.5 and 10 at. %) glasses. Differential scanning calorimetry results under non-isothermal conditions for the studied glasses are reported and discussed. The values of the glass transition temperature (Tg ) and the peak temperature of crystallization (Tp ) were found to be dependent on heating rate and Cd content. From the heating rate dependence of Tg and Tp , the values of the activation energy for glass transition (Eg ) and the activation energy for crystallization (Ec ) were evaluated and their composition dependence discussed. The thermal stability of the glasses was evaluated using various thermal stability criteria such as ΔT, Hg and S. The stability calculations emphasize that the thermal stability decreases with increasing Cd content.

Synthesis, structural characterization and growth features of some (Ph)Se–Cd cluster compounds (Ph = phenyl)

Cd(SePh) 2, CdBr 2·4H 2O/CdI 2 and PCh 3 (Ph = phenyl; PCh 3 = tricyclohexylphosphine) react to give [(SePh) 2Cd 2Br 2(PCh 3) 2] ( 1), [(SePh) 2Cd 2I 2(PCh 3) 2] ( 2) and [(SePh) 7Cd 4Br(PCh 3)] n ( 3). The new compounds are examples of Cd(II) clusters obtained starting from the cluster-forming reagents Cd(SePh) 2 and CdX 2 (X = Br, I) in the presence of variable amounts of PCh 3. While 1 and 2 are single, tetranuclear clusters, compound 3 attains polymeric adamantanoid cages linked through selenium bridges.

The Peter Landin prize

The Peter Landin prize honours the best paper presented at each year's International Symposium on the Implementation and Application of Functional Languages (IFL). It has been awarded every year since 2003, and covers a range of topics including functional operating systems, static analysis for cost information of functional programs, techniques to improve array processing for data locality and parallelism, explicit parallel coordination, supercompilation, and a rational deconstruction of Landin's SECD machine itself. This article describes the history of the prize, explains why Peter Landin was chosen as nominee, and describes each of the articles that have been awarded the prize to date.

An evaluation of the PM 2.5 trace elemental composition in the Venice Lagoon area and an analysis of the possible sources

Global emissions reported by many authors have shown as natural and anthropic sources can contribute to the principal aerosol classes, but values change according the local scenario. The Venice Lagoon is exposed to different anthropic source emissions like vehicular traffic, industrial thermoelectric power plant, petrochemical plant, incinerator plant, domestic heating, ship traffic, glass factories and airport. Samplings of PM 2.5 were daily performed between March and November 2007 in Sacca San Biagio island (Venice), and values of PM 2.5 concentration and element concentration were obtained. Monthly average concentrations (μg m −3) during this period show higher values during the spring and the autumn. A good relationship between data obtained and concentration values from environmental local agencies is evidenced, both for PM 2.5 from urban area (Venezia Mestre), and for PM 10 sampled in the same area, as well as the influence of some meteorological parameters on PM 2.5 concentration sampled. Trace elements samples were measured by an Inductively Coupled Plasma-Quadrupole Mass Spectrometry (ICP-QMS), and values (ng m −3 and μg g −1) for elements regulated by European directives (As, Cd, Ni, Pb), as well as, other elements (Na, Al, K, Ti, V, Mn, Fe, Co, Zn, Se, Ag) are also reported. Data analysis by mean of Principal Component Analysis (PCA) and Positive Matrix Factorization (PMF) pointed out four principal groups of elements like Mn–Fe–K, As–Se–Cd, V–Co, and Pb that could be assigned to specific sources of the Venetian wetland basin.

Biorthogonality, step-indexing and compiler correctness

We define logical relations between the denotational semantics of a simply typed functional language with recursion and the operational behaviour of low-level programs in a variant SECD machine. The relations, which are defined using biorthogonality and stepindexing, capture what it means for a piece of low-level code to implement a mathematical, domain-theoretic function and are used to prove correctness of a simple compiler. The results have been formalized in the Coq proof assistant.