Kerogen structural studies-oxidations with alkaline permanganate and with ferric chloride

Two oxidizing agents were used for structural studies of the kerogen from Aleksinac shale (Yugoslavia), namely: (1) alkaline potassium permanganate, and (2) acidic ferric chloride. (1) The main goal with alkaline permanganate was to obtain optimum yields of identifiable oxidation products with preserved kerogen structural characteristics. In order to find optimal conditions, experiments were carried out at various temperatures (20-100°C) with varying amounts of permanganate per step. The best total yield of isolable degradation products (92,25%) was obtained at 75°C. At the same reaction temperature the best yield of ether-soluble acids was obtained (39% of the total organic matter). Kerogen degradation products obtained in high yields provide a better basis for more reliable structural interpretations than the products obtained in minor yields, which may represent small undefined portions of the original kerogen. (2) Ferric chloride is an oxidant of relatively high oxidation potential, although it is more gentle and more specific (e.g., dehydrogenation and decarboxylation) than most oxidation reagents containing oxygen used in kerogen structural studies. In oxidation of the Aleksinac shale kerogen concentrate with acidic ferric chloride solution, the pyrite content decreased (38-75%), and the kerogen content increased (7-15%). A small portion of the kerogen (∼8%) was degraded into soluble products. The chemical nature of the kerogen was considerably changed. In addition to a decrease in the atomic H C ratio and an increase in the O C ratio, changes in the content of aliphatic, aromatic, carbonyl and quinoid structures were observed

Metal-organic matter interactions in the formation of an oil shale deposit

An attempt was made to distinguish metal-organic matter interactions in two types of sulfate-reducing environments, mild (MR) and strong sulfate-reducing (SR), in the Aleksinac oil shale deposit (Oligocene-Miocene). Samples from the MR group show (all differences are statistically highly significant): lower organic matter content, compared with the SR group, higher O/C and N/C ratios (0.147 ± 0.054 and 0.041 ± 0.014, respectively, compared with 0.125 ± 0.031 and 0.035 ± 0.008, respectively, in the SR group), and higher Cu, Zn, Pb, Cr, Mo and Co contents than in the SR group. Statistically significant correlations between metals, the N/C and the SiO2/Al2O3 ratio in the MR group only, represent a record of highly interdependent processes of organic-metal-silicate interactions which had been occurring in the mild sulfate-reducing conditions during oil shale formation

Efficiency of fenticonazole for the treatment of vaginal candidiasis

Introduction. Uncomplicated vulvovaginal candidiasis appears in 75% women of reproductive age. The most frequent causes are Candida albicans (85-95%) or C. glabrata, and infrequently C. krusei, C. tropicalis, C. parapsilosis, C. pseudotropicalis, etc. Objective. The aim of the study was to investigate efficiency and safety of fenticonazole for vaginal candidiasis treatment. Methods. Therapeutic effect of a single 600 mg fenticonasole vaginal capsule was observed in 417 women, aged 16-67, in five centers in Serbia. In all women, before the treatment, vaginal candidiasis was confirmed by testing of vaginal smear. Based on smear findings and associated symptoms observed on the 7th and 28th day after therapy administration, treatment results were evaluated. On the next day after drug application the patients recorded by using a questionnaire their own feelings on withdrawal symptoms and possible side effects in the period prior to the first control. Results. Control after seven days showed a statistically significant decrease of symptoms. In 385 women, vaginal smear was found negative to yeast and yeast blastospores. Within the first seven days after treatment 84 women had to repeat therapy due to the persistence of symptoms or positive vaginal smear. After 28 days we recorded full recovery in 392 patients, clinical improvement in eight, no change in 16, and deterioration in one patient only. Side effects were very seldom, mostly in the form of a slight redness of the vulva and vagina, and mild itching during several days. Conclusion. Our observations confirmed good efficacy and safety of fenticonazole in the treatment of vaginal candidiasis

The relationship between the loess stratigraphy in the Vojvodina region of northern Serbia and the Saalian and Rissian Stage glaciations – a review

Publication status: PublishedThe regional loess stratigraphy in the Vojvodina region, in the southeastern Carpathian Basin, has often been successfully correlated to the global palaeoclimate. This is a quasi‐continuous sedimentary record that provides detailed environmental reconstruction during the last four glacial/interglacial cycles. In this study, we present a standardized loess stratigraphy and illustrate how it correlates with the marine oxygen isotope and Chinese loess stratigraphical records. We argue that the loess stratigraphy in Vojvodina region is an important link in the integration of European terrestrial stratigraphical schemes and the deep‐sea stratigraphical model. We highlight how the loess record can better illustrate terrestrial environmental change through multiple glacial cycles than other records, such as glacial records. The investigated loess record enables direct links to be made between the loess sediments and their glacial sources. This reveals evidence of glaciations during every glacial cycle of the Saalian Stage complex, equivalent to Marine Isotope Stage (MIS) 10, 8 and 6. Therefore, Serbian loess has the potential to provide a direct link between terrestrial glaciations and wider records of global climate change, which is an enigma for many other continental records. These loess records display a strong relationship with the intensity of European glaciations during different glacial cycles. Loess sedimentation rates are highest in the most intensive European glaciation of the Saalian complex (MIS 6) and much lower during the weaker ‘missing’ glaciations equivalent to MIS 8 and 10. A key observation from the Vojvodina loess is the gradual increase in interglacial aridity through the late Middle Pleistocene. The explanation for the progressively increasing aridity in the investigated region at this time is still unclear. However, this trend is consistent with the idea of the Saalian complex as representing a 400 ka mega glacial cycle modulated by shorter classic 100 ka glacial cycles.</jats:p