Geochemical characteristics of the Chang 7 Member in the southwestern Ordos Basin,China: the influence of sedimentary environment on the organic matter enrichment

The enrichment of organic matter is of great significance to the formation of source rocks, while its mechanism in the Chang 7 Member (Chang 7₁, Chang 7₂, and Chang 7₃ periods) of the southwestern Ordos Basin has not been studied in depth. Forty-eight samples obtained from Chang 7 Member were subjected to rock pyrolysis, gas chromatography-mass spectrometry (GC-MS) analysis, and determination experiments of major and trace elements to evaluate the hydrocarbon potential of the source rock, to reconstruct the sedimentary environment, and to analyze the factors of the organic matter enrichment. The results showed that the average total organic carbon (TOC) contents were 0.70%, 5.48%, and 7.70% for Chang 7₁, Chang 7₂, and Chang 7₃, respectively. From Chang 7₃ to Chang 7₁ period, the contents of TiO₂, Al₂O₃, Fe₂O₃, and P₂O₅ represented a gradual increase of terrigenous input and a gradual decrease in volcanism; the Chemical Alteration Index and the Sr/Cu values reflected warm and humid paleoclimate conditions with a gradual decrease in temperature; the V/(V+Ni) and the Mo-U covariation revealed an anoxic environment with a weakened reduction; and the P/Ti-Cu/Ti model indicated a gradual decrease in paleoproductivity. The linear relationship between indicators of paleoenvironment and TOC indicated that a small amount of terrigenous input, volcanism, warm and humid climate and reducing conditions were more conducive to the enrichment of organic matter; thus we propose a Chang 7₃ organic matter enrichment production model and a Chang 7₁ organic matter enrichment preservation-dilution model.     

Proton-induced X-ray emission (PIXE) analysis of trace elements of total atmospheric deposit (TAD) around a smelting industry: Aerial pollution monitor

This study monitored total atmospheric deposit (TAD) around a smelting plant in Ile-Ife, Nigeria to assess the contributions of the industry to Nigeria's air-shed pollution. Samples were collected for 12 consecutive months using an Australian model gauge, harvested after 30 d of exposure, filtered and dried to constant weights using oven. Monthly deposition rates were determined and elemental characterizations of the TAD samples were done using proton-induced X-ray emission technique. Results revealed that the monthly deposition rates ranged from 0.69 to 4.62 gm^?3 and was more pronounced in Harmattan. Twenty-three elements were detected; their total elemental concentrations ranged from 1.23 to 13.63 mg m^?3 with Fe having the highest concentrations, while Na has the least. Pearson correlation indicated that some elements have common sources and/or similar chemical properties; enrichment factor showed that Fe, Zn, Pb, Mn were extremely enriched in the study area, modified degree of contamination (3.75) and pollution load intensity (1.21) showed that the neighborhoods could be exposed to high air pollution related impacts. Positive matrix factorization model revealed three distinct sources: Smelting emission (63%), biomass burning (17%), and suspended input material emissions (21%). The study concluded that the smelting activities posed a great hazard to receptors around the smelting industry.     

Effects of germanium and silicon on bone mineralization

The chemical properties of Ge are similar to Si. This study investigated whether Ge can substitute for, or is antagonistic to, Si in bone formation. Sixty male weanling Sprague-Dawley rats were randomly assigned to treatment groups of 12 and 6 in a 2×4 factorially arranged experiment. The independent variables were, per gram fresh diet, Si (as sodium metasilicate) at 0 or 25 μg and Ge (as sodium germanate) at 0, 5, 30 or 60 μg. Results confirmed that Ge does not enhance Si deprivation and provided evidence that Ge apparently can replace Si in functions that influence bone composition. When Si was lacking in the diet, calcium and magnesium concentrations of the femur were decreased; this was reversed by feeding either Ge and/or Si. Similar effects were found for zinc, sodium, iron, manganese, and potassium of vertebra. There were some responses to Si deprivation that Ge could not reverse: Ge did not increase femur copper, sodium, or phosphorus or decrease molybdenum of vertebra, effects that were eveked by Si supplementation. Additionally, some findings suggested that 60 μg Ge/g diet could be a toxic intake for the rat. On the other hand, some responses induced by Ge indicate that this element may be acting physiologically other than as a substitute for Si. Germanium itself affected bone composition. Germanium supplementation decreased Si and molybdenum in the femur and increased DNA in tibia. Regardless of the amount of Si fed, animals fed 30 μg Ge/g diet had increased tibial DNA compared to animals fed 0 or 60 μg Ge; however, tibial DNA of animals fed 30 μg Ge was not statistically different from those animals fed 5 μg Ge. Thus, Ge may be of nutritional importance.     

Mathematical analysis of Paleodictyon: a graph theory approach

The graphoglyptid ichnogenus Paleodictyon has been alternatively interpreted as a foraging or farming trace; as a subsurface burrow for the habitation of one or more unknown organisms; the remains of a xenophyophore; and as the result of modular growth of an unknown organism. Graph theory and analysis of the geometry of the regular ichnospecies suggests that if the elements of Paleodictyon are interpreted as tunnels, then they are of extraordinary length relative to the size of any likely solitary tracemaker. In addition, because each vertex of the mesh is of degree three, any possible path through mesh requires revisiting in order to travel through the entire network; this makes the minimum path length even longer. These results suggest that it is unlikely that Paleodictyon is the result of subsurface burrowing.     

Determination of urinary arsenic, mercury, and selenium in steel production workers

The fumes and dust of trace elements and their compounds are very toxic and have been related to an increase in the incidence of diseases. Occupational exposure to toxic metals and metalloids can be determined by means of workplace air measurements and biological monitoring. The aim of our investigation was to determine the concentrations of As, Hg, and Se in urine samples under routine clinical laboratory conditions. To assess the reliability of these methods, critical factors such as detection limit(s), calibration range(s), cost, accuracy, and precision were studied. The method was employed for the quantitative determination of arsenic, mercury, and selenium in urine samples from steel production and quality control workers and healthy unexposed controls. After pretreatment with acids, the samples were digested by means of a microwave oven. Arsenic was determined by hydride atomic absorption spectrometry and mercury was determined by cold vapor atomic absorption spectrometry, whereas selenium was determined by a graphite furnace atomic absorption spectrometry. The results indicate those urinary arsenic, mercury, and selenium levels of the exposed workers are significantly higher than those of the controls. The possibility that these elements are involved in the etiology of diseases is discussed and recommendations are made to improve workplace ventilation and industrial hygiene practices.     

Ruminococcus gnavus plays a pathogenic role in diarrhea-predominant irritable bowel syndrome by increasing serotonin biosynthesis

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Diverse tiering patterns in Paleogene flysch trace fossils,Magura nappe,Carpathian Mountains,Poland

Diversified tiering patterns of trace fossils were observed in three Paleogene lithostratigraphic units of the Magura nappe: the Szczawnica Formation (Paleocene‐early Eocene); the Belove?a beds (middle Eocene); and the Piwniczna Sandstone Member of the Magura Formation (middle‐upper Eocene). Sediments of the first unit were deposited under oxygen‐poor conditions, and those of the second and third units under well‐aerated conditions. Thick‐bedded turbidites and fluxoturbidites of the third unit accumulated quickly, in contrast to ‘normal flysch’ of the first and second units. Analyses of tiering patterns show a thickening of tiers following the improvement of sediment oxygenation. Slowly accumulated deposits of ‘normal’ flysch exhibit a more mature, well‐developed tiering pattern than those which accumulated quickly.     

Precambrian trace fossils and the rise of bilaterian animals

In this attempt to synthesize present knowledge into a coherent story, the Cambrian explosion is interpreted to represent a true adaptive radiation, an event similar to Phanerozoic radiation events in principle but unique in its possibilities. A model of bilaterian evolution helps explain how this particular event involved the sudden initiation of major coelomate phyla. In many of these groups, preservable skeletons are part of the basic body plan. Biochemical‐sequence analyses indicate that acoelomates and pseudocoelomates branched off long before the coelomate radiation. The great differences between Vendian and Cambrian ichnofaunas, therefore, may be the result of a major shift in composition from Vendian acoelomate‐pseudocoelomate‐procoelomate faunas to Phanerozoic faunas dominated by new coelomate groups.     

Determination of plasma trace elements in tumor-bearing animals by proton-induced X-ray emission spectroscopy

Although altered levels of circulating essential trace elements are known to accompany malignant disease, the lack of sensitivity of conventional detection methods has generally limited their study to clinical conditions involving extensive disease (i.e., significant tumor burden). As such, the application of altered trace element levels as potential prognostic guides or as response indicators subsequent to treatment has been of limited use. During this study, proton-induced X-ray emission spectroscopy was evaluated as a tool to determine trace element imbalances in a murine tumor model. Using plasma from C57B1/6 mice bearing the syngeneic Lewis lung carcinoma (LLCa), levels of Fe, Cu, and Zn, as well as changes in the Cu/Zn ratio, were measured in animals carrying an increasing primary tumor burden. The plasma levels of Fe, Cu, and Zn were found to decrease significantly 7 d following implants of LLCa cells with no significant change observed in the Cu/Zn ratio. By d 21, however, an increase in the Cu/Zn ratio was found to accompany increased growth of the LLCa tumor; the plasma levels of Cu had returned to normal levels, whereas both the Fe and Zn plasma levels remained lowered. Collectively, the results suggest that although a net change in individual plasma trace element concentrations might not be accurately associated with tumor growth, a clear relationship was established between the Cu/Zn ratio and tumor size.