Self-curing concrete SC is a concrete type that can be cured without using any external curing regimes. It can perform by several methods such as using lightweight aggregate or chemical agents. In this research chemical curing agent is used to produce SC. This paper reports the results of a research study conducted to evaluate the effect of sulfates on the performance of self-curing concrete compared to ordinary concrete. Samples are immersed in sodium sulfate Na2S04 solution of 4% concentration. Results are measured in terms of compressive strength, tensile strength, flexural strength and mass loss. It was found that the rate of strength loss is noticed at ordinary concrete compared to SC concrete. Sulfate resistance is improved when using self-curing concrete. This improvement appears to be dependent on using a chemical curing agent.
Environmental factors and the addition of adjuvants to the spray tank mix may interfere with glyphosate efficiency in hairy fleabane control. The objective of this study was to evaluate the effect of air temperature and the addition of ammonium sulfate (NH4)2SO4 to glyphosate in the control of glyphosate-resistant (GR) and -susceptible (GS) hairy fleabane. Treatments consisted of air temperatures of 12°C and 25°C, six doses of glyphosate from zero to 2,880 g · ha−1, the presence or absence of (NH4)2SO4 in the spray solution, and one GS and another GR biotype. At the lowest tested dose (180 g · ha−1), control of the GR biotype was 91% and 20% when the plants were kept at 12°C and 25°C, respectively, reducing the resistance factor (RF) by 9.30 times and was associated to the reduction of temperature. The addition of (NH4)2SO4 increased the control by 10−20% at high glyphosate doses and at 25°C. The resistance of hairy fleabane to glyphosate was completely reversed when the plants were maintained at 12°C. At this temperature, resistant plants were controlled even at doses well below that recommended for the control of this species. At 25°C, a dose four times higher than that recommended was required for satisfactory control. At the field level, under situations of low temperatures, it was possible to improve the efficacy of glyphosate applications in hairy fleabane control, if there were no other mechanisms of resistance involved.
In this study, the synthesis of lithium carbonate (Li2CO3) powder was conducted by a carbonation process using carbon dioxide gas (CO2) from waste acidic sludge based on sulfuric acid (H2SO4) containing around 2 wt.% lithium content. Lithium sulfate (Li2SO4) powder as a raw material was reacted with CO2 gas using a thermogravimetric apparatus to measure carbonation conditions such as temperature, time and CO2 content. It was noted that carbonation occurred at a temperature range of 800℃ to 900℃ within 2 hours. To prevent further oxidation during carbonation, calcium sulfate (CaO4S) was first introduced to mixing gases with CO2 and Ar and then led to meet in the chamber. The lithium carbonate obtained was examined by inductively coupled plasma–mass spectroscopy (ICP-MS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) and it was found that of lithium carbonate with a purity above 99% was recovered.
The Silurian Pelplin Formation is a part of a thick, mud-prone distal fill of the Caledonian foredeep, which stretches along the western margin of the East European Craton. The Pelplin Formation consists of organic carbon- rich mudstones that have recently been the target of intensive investigations, as they represent a potential source of shale gas. The Pelplin mudstones host numerous calcite concretions containing authigenic pyrite and barite. Mineralogical and petrographic examination (XRD, optical microscopy, cathodoluminoscopy, SEM-EDS) and stable isotope analyses (δ13Corg, δ13C and δ18O of carbonates, δ34S and δ18O of barite) were carried out in order to understand the diagenetic conditions that led to precipitation of this carbonate-sulfide-sulfate paragenesis and to see if the concretions can enhance the understanding of sedimentary settings in the Baltic and Lublin basins during the Silurian. Barite formed during early diagenesis before and during the concretionary growth due to a deceleration of sedimentation during increased primary productivity. The main stages of concretionary growth took place in yet uncompacted sediments shortly after their deposition in the sulfate reduction zone. This precompactional cementation led to preferential preservation of original sedimentary structures, faunal assemblages and early- diagenetic barite, which have been mostly lost in the surrounding mudstones during burial. These components allowed for the reconstruction of important paleoenvironmental conditions in the Baltic and Lublin basins, such as depth, proximity to the detrital orogenic source and marine primary productivity. Investigation of the concretions also enabled estimation of the magnitude of mechanical compaction of the mudstones and calculation of original sedimentation rates. Moreover, it showed that biogenic methane was produced at an early-diagenetic stage, whereas thermogenic hydrocarbons migrated through the Pelplin Formation during deep burial.
Measurements were made of sediment characteristics, benthic microbial activity and optimum temperature for sulfate reduction at Signy Island, South Orkney Islands, Antarctica . There was little evidence to support any seasonal variation in oxygen penetration of surface sediments. Oxygen penetrated to only 1.5 to 3 mm throughout the year, despite bioturbation from a dense amphipod population. The distribution of acid volatile sulfides increased with depth below 1 cm and above this, surface sediments were lighter in colour and contained fewer sulfides. The rates of sulfate reduction increased during winter under sea-ice cover, and remained high after ice break up. Seasonal water temperature was relatively constant between –1.8 and 0.5°C. Optimum temperature for anaerobic sediment respiration was investigated using different substrates and was found to be in the range 17–27°C, suggesting that sulfate reducing bacteria are psychrotolerant as they were inhibited by low temperatures.