scholarly journals THE STUDY OF DEHYDRATION OF COLEMANITE IN NON-ISOTHERMAL CONDITIONS

2021 ◽  
Vol 6 (3) ◽  
pp. 97-106
Author(s):  
V. Bessmertnyy ◽  
M. Bondarenko ◽  
O. Puchka ◽  
A. Cherkasov ◽  
I. Izotova ◽  
...  
Keyword(s):  
Mass Loss ◽  
Kinetic Curve ◽  
Fluorescence Analysis ◽  
Hydroxyl Groups ◽  
Isothermal Conditions ◽  
Second Stage ◽  
Total Mass Loss ◽  
Mechanism Of Dehydration ◽  
Stage Process ◽  
Heating Up

The regularities of colemanite dehydration under non-isothermal conditions are investigated. It is established that colemanite, supplied to the Russian Federation from Turkey, has calcite in its composition. The chemical composition of colemanite is determined using the X-ray fluorescence analysis method. It is shown that the processes of dehydration of colemanite under non-isothermal conditions at a heating rate of 10 °С / min are accompanied by two endothermic effects at 660,7 K and 675,7 K with a total mass loss of 17,3 %. The rate of mass loss of colemanite from the temperature at heating up to 773 K, at which colemanite dehydrates and passes into the amorphous phase, is also studied. The regularities of changes in the rate of dehydration of colemanite are established. It is shown that the maximum values of the dehydration rate of colemanite are observed in the temperature range of 653–678 K. The activation energy of colemanite dehydration is determined to be 86,000 J/mol. Based on the experimentally obtained data, the rate constant of the colemanite dehydration process is calculated. The process of dehydration of colemanite is adequately described by the formal equation of kinetics. Most of the kinetic curve is adequately described by the resulting kinetic equation. It is proposed to describe the mechanism of dehydration of colemanite by a two-stage process, accompanied at the first stage by the removal of crystallization water, and at the second stage-by the removal of hydroxyl groups

Fullerene-like Nanoparticles of WS2 as a Promising Protection from Erosive Wear of Gun Bore Nozzles

2020 ◽  
Vol 16 (1) ◽  
pp. 62-70 ◽  
Author(s):  
Narimane Rezgui ◽  
Danica Simić ◽  
Choayb Boulahbal ◽  
Dejan Micković
Keyword(s):  
Mass Loss ◽  
Solid Lubricant ◽  
Erosive Wear ◽  
Mechanical Resistance ◽  
Protective Function ◽  
Protective Layers ◽  
Total Mass Loss ◽  
Mass Losses ◽  
Before And After ◽  
Tube Life

Background: Erosive wear causes increase in the bore diameter of firearms barrels and nozzles. Most responsible factors for this erosion are friction and heat generated during the shot. Protection from erosive wear is very important for gun tube life cycle, and various protection methods are used: adding phlegmatizers in gunpowder composition or applying protective layers on the gun bore inner surface. Objective: In this research, a possibility is examined to protect the surface of a nozzle exposed to gunpowder erosion applying a layer of tungsten disulfide fullerene-like nanoparticles, IF-WS2, known as outstanding solid lubricant of a great mechanical resistance. Methods: Nanoparticles on the nozzle surface before and after the gunfire tests were observed using scanning electron microscopy/energy dispersive X-ray spectroscopy. Gunfire tests were performed on designed erosion device. Temperatures in the defined position near the affected surface were measured with thermocouples and compared for the nozzles with and without nanoprotection, as well as the nozzle mass loss after each round. Results: For the sample with IF-WS2 lower temperatures after firing and lower mass losses were observed. Mass loss after first round was 25.6% lower for the sample with protective nanoparticles layer, and the total mass loss was about 5% lower after five rounds. After the first round the nozzle without IF-WS2 was heated up to a temperature which was for 150.8°C higher than the nozzle with IF-WS2. Conclusion: Protective function of IF-WS2 is the most pronounced for the first round. The observed results encourage its further application in firearms gun bores protection.

Study on Drying Characteristics of Microalgae under Different Conditions

2013 ◽  
Vol 724-725 ◽  
pp. 296-299
Author(s):  
Chun Xiang Chen ◽  
Xiao Qian Ma ◽  
Xiao Cong Li ◽  
Wei Ping Qin
Keyword(s):  
Moisture Content ◽  
Mass Loss ◽  
Fresh Water ◽  
Chlorella Vulgaris ◽  
Drying Process ◽  
Drying Time ◽  
Drying Characteristics ◽  
Second Stage ◽  
Drying System ◽  
Two Stages

To find out an alternative of coal saving, a kind of microalgae, Chlorella vulgaris (C. vulgaris) which is widespread in fresh water was studied by digital blast drying system. The effect of the moisture content, drying thickness and temperature on the drying process of C. vulgaris were investigated. The results indicated that when the drying temperature is high, the moisture content is low and the material thickness is small, the drying time is short. The drying process of C.vulgaris can be divided into two stages, and the mass loss is mainly occurred in the second stage . The results will provide guidance for design of drying process and dryer of microalgae.

Leaching of Am-241 from a Radioactive Waste Glass Corroded in the Presence of Stainless Steel Corrosion Products and/or Bentonite

1987 ◽  
Vol 112 ◽  
Author(s):  
Masaki Tsukamoto ◽  
Inga-Kari Björner ◽  
Hilbert Christensen ◽  
Hans-Peter Hermansson ◽  
Lars Werme
Keyword(s):  
Stainless Steel ◽  
Radioactive Waste ◽  
Mass Loss ◽  
Total Mass ◽  
Corrosion Behaviour ◽  
Steel Corrosion ◽  
Waste Glass ◽  
Corrosion Products ◽  
Total Mass Loss ◽  
Elemental Mass

AbstractThe release of Am-241 during corrosion of the radioactive waste glass, JSS-A, has been studied in the presence of corrosion products and/or uncom-pacted bentonite. The corrosion behaviour of Am-241 has been analyzed using gamma spectrometry. Adsorption of Am-241 on bentonite is observed in all cases. The contents of Am-241 in centrifuged leachates are in most cases less than 1/100 of total values. The normalized elemental mass loss of Am increases initially with corrosion time, and the values in the presence of bentonite and corrosion products are larger than those in the presence of bentonite alone. This tendency is in agreement with results previously found for other elements. The release of Am is low, only about 10–20 % of the corresponding total mass loss.

scholarly journals A new methodology for polyvalent intravenous immunoglobulin solution production with a two-stage process of viral inactivation

2010 ◽  
Vol 46 (4) ◽  
pp. 777-783
Author(s):  
Antônio Edson de Souza Lucena ◽  
Divaldo de Almeida Sampaio ◽  
Ednaldo Rosas da Silva ◽  
Virgínia Florêncio de Paiva ◽  
Ana Cláudia Santiago ◽  
...  
Keyword(s):  
Intravenous Immunoglobulin ◽  
Immunoglobulin G ◽  
Cation Exchanger ◽  
Product Analysis ◽  
Viral Inactivation ◽  
Two Stage ◽  
Second Stage ◽  
Neutralizing Capacity ◽  
Stage Process ◽  
Sodium Caprylate

Highly purified intravenous immunoglobulin G concentrate (IV IgG) was produced with the use of polyethylene glycol associated to a single-stage precipitation by ethanol, instead of the classic Cohn-Oncley process, which employs cold alcohol as the precipitating agent, in a three-stage process. Precipitation of crude fraction containing more than 95% of immunoglobulin G was performed by liquid chromatography with a cation exchanger, CM-Sepharose, as a stationary phase. During the process, the product was subjected to two-stage viral inactivation. The first stage was performed by the action of sodium caprylate, 30 mM at pH 5.1+/- 0.1, and the second stage was performed by the action of a solvent-detergent mixture. The finished product was formulated at 5% with 10% sucralose as the stabilizing agent. The process yields 3.3g of IgG/liter of plasma. The finished product analysis showed an anti-complementary activity lower than 1CH50. Polymer and aggregate percent levels were lower than 3% in the five batches studied. The analysis of neutralizing capacity showed the presence of antibacterial and antiviral antibodies in at least three times higher concentrations than the levels found in source plasma. The finished product fulfilled all purity requirements stated in the 4th edition of the European pharmacopeia.

scholarly journals Ocean-driven thinning enhances iceberg calving and retreat of Antarctic ice shelves

2015 ◽  
Vol 112 (11) ◽  
pp. 3263-3268 ◽  
Author(s):  
Yan Liu ◽  
John C. Moore ◽  
Xiao Cheng ◽  
Rupert M. Gladstone ◽  
Jeremy N. Bassis ◽  
...  
Keyword(s):  
Mass Loss ◽  
Mass Balance ◽  
Climate Forcing ◽  
Empirical Estimate ◽  
Positive Mass ◽  
Ice Shelves ◽  
Total Mass Loss ◽  
Rapid Changes ◽  
Iceberg Calving ◽  
Ice Sheet Mass Balance

Iceberg calving from all Antarctic ice shelves has never been directly measured, despite playing a crucial role in ice sheet mass balance. Rapid changes to iceberg calving naturally arise from the sporadic detachment of large tabular bergs but can also be triggered by climate forcing. Here we provide a direct empirical estimate of mass loss due to iceberg calving and melting from Antarctic ice shelves. We find that between 2005 and 2011, the total mass loss due to iceberg calving of 755 ± 24 gigatonnes per year (Gt/y) is only half the total loss due to basal melt of 1516 ± 106 Gt/y. However, we observe widespread retreat of ice shelves that are currently thinning. Net mass loss due to iceberg calving for these ice shelves (302 ± 27 Gt/y) is comparable in magnitude to net mass loss due to basal melt (312 ± 14 Gt/y). Moreover, we find that iceberg calving from these decaying ice shelves is dominated by frequent calving events, which are distinct from the less frequent detachment of isolated tabular icebergs associated with ice shelves in neutral or positive mass balance regimes. Our results suggest that thinning associated with ocean-driven increased basal melt can trigger increased iceberg calving, implying that iceberg calving may play an overlooked role in the demise of shrinking ice shelves, and is more sensitive to ocean forcing than expected from steady state calving estimates.

scholarly journals Two-Stage Discrete Mechanical Modelin Three-Dimensional Space for Garment Simulation

2019 ◽  
Vol 19 (1) ◽  
pp. 26-35 ◽  
Author(s):  
Xuan Luo ◽  
Gaoming Jiang ◽  
Honglian Cong
Keyword(s):  
Mechanical Model ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Mathematical Expression ◽  
Two Stage ◽  
Second Stage ◽  
Simulation Speed ◽  
Optimal Value ◽  
Variable Distance ◽  
Stage Process

Abstract This paper focuses on the better performance between the garment simulation result and the simulation speed. For simplicity and clarity, a notation “PART” is defined to indicate the areas between the garment and the human body satisfying some constraints. The discrete mechanical model can be achieved by the two-stage process. In the first stage, the garment can be divided into several PARTs constrained by the distance. In the second stage, the mechanical model of each PART is formulated with a mathematical expression. Thus, the mechanical model of the garment can be obtained. Through changing the constrained distance, the simulation result and the simulation speed can be observed. From the variable distance, a desired value can be chosen for an optimal value. The results of simulations and experiments demonstrate that the better performance can be achieved at a higher speed by saving runtime with the acceptable simulation results and the efficiency of the proposed scheme can be verified as well.

Changes in glacier extent and surface elevations in the Depuchangdake region of northwestern Tibet, China

2016 ◽  
Vol 85 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Zhiguo Li ◽  
Lide Tian ◽  
Hongbo Wu ◽  
Weicai Wang ◽  
Shuhong Zhang ◽  
...  
Keyword(s):  
Mass Loss ◽  
Remote Sensing Data ◽  
Shuttle Radar Topography Mission ◽  
Thematic Mapper ◽  
Glacier Retreat ◽  
Maximum Temperature ◽  
Glacier Mass Balance ◽  
Laser Altimeter ◽  
Total Mass Loss ◽  
Elevation Model

Remote sensing data, including those from Landsat Thematic Mapper/Enhanced Thematic Mapper Plus (TM/ETM +), the Shuttle Radar Topography Mission Digital Elevation Model (SRTM4.1 DEM), and the Geoscience Laser Altimeter System Ice, Cloud, and Land Elevation Satellite (Glas/ICESat), show that from 1991 to 2013 the glacier area in the Depuchangdake region of northwestern Tibet decreased from 409 to 393 km2, an overall loss of 16 km2, or 3.9% of the entire 1991 glacial area. The mean glacier-thinning rate was − 0.40 ± 0.16 m equivalent height of water per year (w.e./yr), equating to a glacier mass balance of − 0.16 ± 0.07 km3 w.e./yr. Total mass loss from 2003 to 2009 was − 1.13 ± 0.46 km3. Glacier retreat likely reflects increases in annual total radiation, annual positive degree days, and maximum temperature, with concurrent increases in precipitation insufficient to replenish glacial mass loss. The rate of glacier retreat in Depuchangdake is less than that for Himalayan glaciers in Indian monsoon-dominated areas, but greater than that for Karakoram glaciers in mid-latitude westerly-dominated areas. Glacier type, climate zone, and climate change all impact on the differing degrees of long-term regional glacial change rate; however, special glacier distribution forms can sometimes lead to exceptional circumstances.

An Anaerobic Process for Treatment of CTMP Effluent

1988 ◽  
Vol 20 (1) ◽  
pp. 143-147 ◽  
Author(s):  
T. Welander
Keyword(s):  
Volatile Fatty Acids ◽  
Anaerobic Bacteria ◽  
Methanogenic Bacteria ◽  
Second Stage ◽  
The Third ◽  
Multi Stage ◽  
Third Stage ◽  
Aluminum Iron ◽  
Stage Process ◽  
Iron And Calcium

A multi-stage process for treatment of CTMP effluent has been developed. It comprises primary settling and four biological stages. The concentration of hydrogen peroxide, a compound which is toxic to anaerobic bacteria, is reduced in the first biological stage by means of the biocatalytic action of biomass that is recycled from the following acidogenic and/or aerobic stages. The second stage is an acidogenic stage, in which volatile fatty acids are formed and remaining peroxide is decomposed. A mixture of aluminum, iron and calcium salts is added to the effluent in order to detoxify compounds which are toxic to methanogenic bacteria. The main part of the COD and BOD removal takes place in the third stage, the methanogenic stage, after which follows an aerobic stage for polishing and removal of bad-smelling compounds. The COD and BOD7 removals in the anaerobic part of the process are 60 and 90 %, respectively, and the methane yield is 0.20-0.25 Nm3/kg COD removed.

scholarly journals Tequila Still Distillation Fractioned Residual Streams for Use in Biorefinery

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6222
Author(s):  
Edgardo Martinez-Orozco ◽  
Pablo Gortares-Moroyoqui ◽  
Norberto Santiago-Olivares ◽  
Juan Napoles-Armenta ◽  
Ruth Gabriela Ulloa-Mercado ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Gas Chromatography ◽  
Energy Analysis ◽  
Oxygen Demand ◽  
Solid Content ◽  
Co2 Production ◽  
Second Stage ◽  
Stage Process ◽  
Very High ◽  
Tequila Vinasses

Tequila vinasses is a mixture made from up to six still distillation two-stage process residual effluents. First stage fractions: residual must (60%), heads (0.9%) and tails (20.0%); second stage fractions: non-evaporated (8.0%), heads (0.1%) and tails (1.0%); the result is a more complex effluent for its treatment or biorefining. The objectives of this study were to: (a) characterize the five still distillation volatile streams in the Tequila 100% Agave processing; compounds: methanol, ethanol, acetaldehyde, ethyl acetate, sec-butanol, n-propanol, iso-butanol, n-butanol, iso-amyl, n-amyl, and ethyl lactate were detected by gas chromatography; calculated chemical oxygen demand from chemical composition had very high values (53,760–1,239,220 mg/L); measurement of pH (3.24–4.80), color (38.6 UC Pt-Co max), turbidity (46.1 max), electrical conductivity (3.30–172.20 μS/cm), and solid content (0 mg/L) was also made; (b) report an energy analysis (2.02 × 109 KWh) and CO2 production (429 × 106 kg) in the Tequila industry during 2019; (c) up to date residues (365.2 × 106 kg agave bagasse, 1146.1 × 106 kg agave leaves and 3300.0 × 106 L agave vinasse) in 2019; (d) economic analysis, current tequila vinasses treatment price is 16.00 USD/m3 but could reach a considerable fraction value if is bio-refined, a break down component analysis reach for five volatile streams $51.23–$140.00 USD/m3.

scholarly journals Simulated retreat of Jakobshavn Isbræ during the 21st century

2019 ◽  
Vol 13 (11) ◽  
pp. 3139-3153 ◽  
Author(s):  
Xiaoran Guo ◽  
Liyun Zhao ◽  
Rupert M. Gladstone ◽  
Sainan Sun ◽  
John C. Moore
Keyword(s):  
Mass Loss ◽  
21St Century ◽  
Three Dimensional ◽  
Climate Scenario ◽  
Ice Shelf ◽  
Ice Flow ◽  
Early 21St Century ◽  
Total Mass Loss ◽  
Grounding Line ◽  
Earth System Models

Abstract. The early 21st century retreat of Jakobshavn Isbræ into its overdeepened bedrock trough was accompanied by acceleration to unprecedented ice stream speeds. Such dramatic changes suggested the possibility of substantial mass loss over the rest of this century. Here we use a three-dimensional ice sheet model with parameterizations to represent the effects of ice mélange buttressing, crevasse-depth-based calving and submarine melting to adequately reproduce its recent evolution. We are the first study on Jakobshavn Isbræ that solves for three-dimensional ice flow coupled with representations of hydro-fracturing-induced calving and mélange buttressing. Additionally, the model can accurately replicate interannual variations in grounding line and terminus position, including seasonal fluctuations that emerged after arriving at the overdeepened basin and the disappearance of its floating ice shelf. Our simulated ice viscosity variability due to shear margin evolution is particularly important in reproducing the large observed interannual changes in terminus velocity. We use this model to project Jakobshavn's evolution over this century, forced by ocean temperatures from seven Earth system models and surface runoff derived from RACMO, all under the IPCC RCP4.5 climate scenario. In our simulations, Jakobshavn's grounding line continues to retreat ∼18.5 km by the end of this century, leading to a total mass loss of ∼2068 Gt (5.7 mm sea level rise equivalent). Despite the relative success of the model in simulating the recent behavior of the glacier, the model does not simulate winter calving events that have become relatively more important.

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