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Number of results: 10
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Abstract

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.

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Authors and Affiliations

A.A. Bashandy
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Abstract

Biochar was prepared from corn ( Zea mays) stalks and impregnated with sulfuric acid. The biomass was impregnated for 24 h with a 50% solution of H2SO4 with impregnation ratios 1:2 (B 1:2) and 1:3 p/v (B 1:3); then, it was carbonized in a muffle furnace at 520°C for 30 min with a 10°C per min ramp. The adsorption capacity to remove anions (nitrate, sulfate, and phosphate) in an aqueous solution was evaluated by varying the temperature. The adsorption mechanism was studied by determining the thermodynamic parameters: Gibbs free energy (ΔGº), enthalpy (ΔHº) and entropy (ΔSº) standard. The biochars were characterized by Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) analysis and were found to exhibit a heterogeneous surface and porous nature, with C, O, S, and Si. The experiments in the batch system showed the best performance of B 1: 2 in the removal of the three anions occurred at 303 K, while B 1: 3 had the best performance at 298 K. From the thermodynamic parameters, it was found that the removal processes are endothermic, their mechanism is by chemisorption. It is concluded that synthesized biochar is an excellent alternative to removing nutrient anions present in the solution.
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Authors and Affiliations

Ángel Villabona-Ortiz
1
Candelaria Tejada-Tovar
1
ORCID: ORCID
Rodrigo Ortega-Toro
2
ORCID: ORCID

  1. Universidad de Cartagena, Faculty of Engineering, Department of Chemical Engineering, Cartagena de Indias, Colombia
  2. Universidad de Cartagena, Faculty of Engineering, Department of Food Engineering, Avenida Del Consulado 48-152, Cartagena 130014, Colombia
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Abstract

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.

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Authors and Affiliations

Giliardi Dalazen
Alexandre Pisoni
Christian Menegaz
Aldo Merotto Jr.
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Abstract

Ligninolytic enzymes are employed for the production of second-generation biofuel to minimize fuel crisis. Additionally, they play a crucial role in global carbon cycle and a variety of applications in food, agriculture, paper and textile industries. On a large scale production of ligninolytic enzymes, microorganisms can be cultured on lignocellulosic wastes. In the present study, proximate analysis including acid detergent lignin (ADL), acid detergent cellulose (ADC), acid detergent fi ber (ADF) and acid insoluble ash (AIA) were performed for Platanus orientalis (chinar), Bauhinia variegata (orchid tree), Pinus roxburghii (chir pine), wheat straw and wheat husk. Platanus orientalis was selected as substrate because of higher lignin contents for the production of ligninolytic enzymes by Aspergillus flavus. Solid State Fermentation was used and Response Surface Methodology was employed for optimizing various parameters and enzymes production. Maximum production was achieved at temperature 32°C, fermentation period 120 hours, pH 4.5, inoculums size 3.5 mL, substrate mesh size 80 mm, substrate size 7 g. Maximum purifi cation of laccase, manganese peroxidase (MnP) and lignin peroxidase (LiP) was achieved with 50%, 60% and 40% ammonium sulfate respectively and it was enhanced by gel filtration chromatography. Characterization of enzymes shows that Laccase has 35°C optimum temperature, 4.5 pH, 0.289 mM Km and 227.27 μM/ml Vmax. Manganese peroxidase has 30°C optimum temperature, 5.5 pH, 0.538 mM Km and 203.08 μM/ml Vmax. Lignin peroxidase has 30°C optimum temperature, 3 pH, 2 mM Km and 2000 µM/ml Vmax. Protein concentrations found in crude extracts and partially purified enzymes are respectively: laccase 1.78 and 0.71 mg/ml, MnP 1.59 and 0.68 mg/ml. LiP, 1.70 and 0.69 mg/ml.
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Authors and Affiliations

Jehangir Khan
1 3
Muahammad Javaid Asad
1
Raja Tahir Mahmood
2
Feeroza Hamid Wattoo
1
Tayyaba Zainab
1
Sidrah Nazir
1
Muhammad Basir Shah
4
Dawood Ahmed
5

  1. University Institute of Biochemistry and Biotechnology, PMAS-Arid Agriculture University Rawalpindi, Pakistan
  2. Department of Biotechnology, Mirpur University of Science and Technology (MUST), Mirpur-10250 (AJK), Pakistan
  3. Department of Biosciences, University of WAH, WAH Pakistan
  4. Department of Plant Breeding & Genetics, Balochistan Agriculture College Quetta, Pakistan
  5. Department of Medical Laboratory Technology, Haripur University, Haripur, KPK, Pakistan
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Abstract

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.

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Authors and Affiliations

Dong Hyeon Choi
Jei Pil Wang
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Abstract

A method to improve the quality of purifi ed water, reduce the cost of reagents for the regeneration of resin and create low-waste processes have been developed. This paper presents the results of ion exchange separation of sulfates and nitrates using AV-17-8 anion exchange resin in NO3 form. The effi ciency of anion separation on the highly basic anion exchange resin AV-17-8 depends on the magnitude and ratio of their concentrations in water. Separation on the AV-17-8 anion exchange resin has been shown to be eff ective at concentrations of sulfates up to 800 mg/dm3 and nitrates up to 100 mg/dm3. Conditions for regeneration of 10% NaNO3 anion exchange resin were determined. Reagent precipitation of sulfates from the used regeneration solution in the form of calcium sulfate was carried out. Calcium sulfate precipitate can be used in the manufacturing of building materials. The regeneration solution is suitable for reuse. The developed results will allow to introduce low-waste desalination technology of highly mineralized waters.
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Authors and Affiliations

Inna Trus
1
ORCID: ORCID
Mukola Gomelya
1
ORCID: ORCID
Viktoria Vorobyova
1
ORCID: ORCID
Margarita Skіba
2
ORCID: ORCID

  1. National Technical University of Ukraine «Igor Sikorsky Kyiv Polytechnic Institute», Kyiv, Ukraine
  2. Ukrainian State Chemical-Engineering University, Dnipro, Ukraine
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Abstract

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.

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Authors and Affiliations

Maciej J. Bojanowski
Artur Kędzior
Szczepan J. Porębski
Magdalena Radzikowska
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Abstract

In a corrosive environment with coupled dry-wet-sulfate action, concrete structures are susceptible to erosion by sulfate ions, which seriously affects the safe operating life. To forecast the operational lifetime of concrete below the influence of the dry-wet cycle and sulfate erosion environment, four different admixtures of polypropylene fiber: 0, 0.6, 0.9, and 1.2 kg/m 3, were incorporated into concrete specimens, and indoor accelerated tests were designed to observe the macroscopic and microscopic deterioration law analysis of concrete specimens; using the precept of damage mechanics, the damage of concrete under solubility cycle was established. The damage evolution equation of concrete under freeze-thaw cycles was established and the operational life of concrete was predicted. The results showed that the overall mass loss rate of concrete specimens increased with the number of tests, and the relative energetic modulo decreased with the number of tests; the pore change pattern, microstructure, and internal material composition of specimens under different working conditions were obtained by using NMR scanning technique, SEM electron microscope scanning technique and XRD physical phase analysis technique. The damage evolution equation shows that adding a certain amount of polypropylene fiber to concrete can improve the working life of concrete under dry and wet connected sulfate assault.
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Authors and Affiliations

Nan Nie
1
ORCID: ORCID

  1. Station Building Construction Department, China Railway Guangzhou Bureau Group Co., China
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Abstract

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.

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Authors and Affiliations

Tony R. Walker

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