scholarly journals Corrosion Level of Rock Bolts Exposed to Aggressive Environments in Nordic Road Tunnels

2021 ◽  
Author(s):  
Cristobal Javier Manquehual ◽  
Pål Drevland Jakobsen ◽  
Amund Bruland
Keyword(s):  
Steel Corrosion ◽  
Cold Climate ◽  
High Concentration ◽  
Rock Support ◽  
Rock Bolts ◽  
Tunnel Excavation ◽  
Support Measure ◽  
Deicing Salts ◽  
Road Tunnels ◽  
Kinetics Of

AbstractFor road tunnels in most Nordic countries, temporary rock support installed during tunnel excavation usually becomes a part of the permanent rock support. Rock bolts are the most common rock support measure in road tunnels excavated in hard rock, and their conditions over the period of tunnel operation play a significant role in the safety of these tunnels. The rock bolt types and aggressive environmental conditions considered in this research are focused on those used and observed in Norwegian and Swedish road tunnels. Findings elsewhere in similar environments are included to highlight the different kinetics of degradation. Based on the collected data, the corrosion levels in these road tunnels are comparable to those in the most polluted industrial areas. Aggressive groundwater conditions for rock bolts include a groundwater pH below four (which can be caused by sulfuric acid formation due to the oxidation of the mineral pyrite in the rock), marine groundwater, and flowing groundwater with a high concentration of dissolved oxygen. Furthermore, chloride-bearing deicing salts commonly used on roads located in cold climate regions during winter can promote corrosion in rock bolts from the tunnel room. For these environments, this research proposes a lognormal probability function to quantify the expected steel corrosion level for 25, 50, and 100 years of exposure time. The corrosion protection given by cement grouting, hot-dip galvanizing and epoxy coating are also addressed to explore their contributions to the lifespan extension of rock bolts in acidic and chloride-rich environments.

Vancomycin Adsorption During in vitro Model of Hemoperfusion with HA380 Cartridge

Nephron ◽  
2021 ◽  
pp. 1-7
Author(s):  
Ilaria Godi ◽  
Anna Lorenzin ◽  
Silvia De Rosa ◽  
Gianlorenzo Golino ◽  
Maira Knust ◽  
...  
Keyword(s):  
Complete Removal ◽  
Potential Interaction ◽  
Blood Purification ◽  
Therapeutic Monitoring ◽  
High Concentration ◽  
Langmuir Isotherm Model ◽  
Vitro Model ◽  
Kinetics Of ◽  
Balanced Solution

<b><i>Introduction:</i></b> A critical point for using blood purification during sepsis may be the potential interaction with antimicrobial therapy, the mainstay of sepsis treatment. The aim of our study was to investigate the vancomycin removal during hemoperfusion (HP) using HA380 cartridge. <b><i>Methods:</i></b> This is an experimental study, in which 500 mL of solution was circulated in a closed-circuit (blood flow of 250 mL/min) simulating HP ran using HA380. Vancomycin was added to reach a through concentration or a very high concentration to evaluate the removal ratio (RR) during 120 min of HP. Comparison between blood-crystalloid solution and balanced solution was performed by using Kruskal-Wallis test. The kinetics of vancomycin removal and the adsorption isotherm were evaluated. <b><i>Results:</i></b> We found a complete removal of vancomycin at baseline through concentration of 23.0 ± 7.4 mg/L. Using extremely high concentration (baseline 777.0 ± 62.2 mg/L), RR was 90.1 ± 0.6% at 5 min and 99.2 ± 0.6% at 120 min. No difference in terms of RR was found between blood-crystalloid mixture and balanced solution. The kinetics of the vancomycin reduction followed an exponential decay. Repeated boluses (total amount of 2,000 mg) resulted in cumulative adsorption of 1,919.4 mg with RR of 96.6 ± 1.4%, regardless of the amount injected (100 vs. 500 mg). Vancomycin adsorption onto HA380 followed the Langmuir isotherm model. <b><i>Conclusions:</i></b> A considerable amount of vancomycin was rapidly removed during in vitro HP with HA380. Clinical studies are needed to determine whether this may lead to underdosing. Drug therapeutic monitoring is highly recommended when using HA380 for blood purification in patients receiving vancomycin.

scholarly journals Leaching Titaniferous Magnetite Concentrate by Alkaline Aqueous Solution

2021 ◽  
Author(s):  
Ke Guo ◽  
Shaoyan Wang ◽  
Renfeng Song ◽  
Zhiqiang Zhang
Keyword(s):  
Aqueous Solution ◽  
Alkali Concentration ◽  
Water Usage ◽  
X Ray Diffraction ◽  
High Concentration ◽  
X Ray ◽  
Iron Concentrate ◽  
Titaniferous Magnetite ◽  
Magnetite Concentrate ◽  
Kinetics Of

AbstractLeaching titaniferous magnetite concentrate with alkali solution of high concentration under high temperature and high pressure was utilized to improve the grade of iron in iron concentrate and the grade of TiO2 in titanium tailings. The titaniferous magnetite concentrate in use contained 12.67% TiO2 and 54.01% Fe. The thermodynamics of the possible reactions and the kinetics of leaching process were analyzed. It was found that decomposing FeTiO3 with NaOH aqueous solution could be carried out spontaneously and the reaction rate was mainly controlled by internal diffusion. The effects of water usage, alkali concentration, reaction time, and temperature on the leaching procedure were inspected, and the products were characterized by X-ray diffraction, scanning electron microscope, and energy dispersive spectroscopy, respectively. After NaOH leaching and magnetic separation, the concentrate, with Fe purity of 65.98% and Fe recovery of 82.46%, and the tailings, with TiO2 purity of 32.09% and TiO2 recovery of 80.79%, were obtained, respectively.

scholarly journals Κινητική της αμμωνίας εις το περιτοναϊκόν υγρόν

1968 ◽  
Author(s):  
Αναστάσιος Εμμανουήλ
Keyword(s):  
Ascitic Fluid ◽  
Peritoneal Fluid ◽  
Ammonium Citrate ◽  
Blood Ammonia ◽  
High Concentration ◽  
Group 2 ◽  
Fixed Times ◽  
Kinetics Of ◽  
Cirrhotic Group ◽  
Group 1

The kinetics of ammonia between blood and peritoneal fluid on 18 patiens was studied. Ten grams of ammonium citrate were given by mouth; the concentrations of ammonia in the blood and in the peritoneal fluid were comprared after determining the values at fixed times. The cases were divided in two groups: group 1, included eight patients with cirrhosis of the liver, group 2, included patients with ascites of other than liver cirrhosis aetiology, five of whom had carcinoma of the liver and'or of the peritoneal, two patients with lymphosarcoma, one with kidneysarcoma (Bour neville Syndrome) and two cases with congestive heart failure. The following conclusions have drawn : 1. The ammonia concentrations in the ascitic fluid of the cirrhotic group (group 1) before ammonium citrate loading was found to be higher than in the blood. 2. The highest concentration of the ammonia in the ascitic fluid was found two hours after loading and fell to the pre-loading level three hours later. 3. The curve formed by the ammonia values and ascitic fluid is similar to that of the blood. 4. The values of blood —and ascitic fluid—ammonia and the respective ourves in cases of cardiac failure resembled those found in cirrhotics. 5. In cases of neoplasms the fluctuations of ammonia concentrations in the blood and in the peritoneal fluid are minimal and the curves are flat. 6. In lymphosarcoma and kidneysarcoma the pre-loading values of blood ammonia are higher than in the peritoneal fluid.7. High concentration of blood and peritoneal fluid ammonia without appreciable fluctuations might suggest liver cancer on cirrhotic substrate.

Modelling of microbial processes that govern degradation of organic substrates in soil, with special reference to pesticides

1990 ◽  
Vol 329 (1255) ◽  
pp. 369-373 ◽  
Keyword(s):  
Microbial Population ◽  
Large Fraction ◽  
Organic Substrates ◽  
High Concentration ◽  
Deterministic Models ◽  
Soil Microbial ◽  
Low Concentrations ◽  
Biokinetic Parameters ◽  
Soil Microbial Population ◽  
Kinetics Of

We tried to develop deterministic models for kinetics of 2,4-D breakdown in the soil based on the following considerations: (i) at low concentrations degradation results from maintenance consumption by a large fraction of the soil microbial population; (ii) at high concentration in addition to the maintenance consumption there is a growth-associated carbon incorporation by a small specific microbial population. Values for the biokinetic parameters are consistent with those commonly found in the literature. Comparison between observed and simulated curves suggests that a non-negligible part of the pesticidal carbon exists as microbial by-products.

scholarly journals Effect of HCO3− on electrochemical kinetics of carbon steel corrosion in CO2-saturated brines

2018 ◽  
Vol 290 ◽  
pp. 626-638 ◽  
Author(s):  
Ruishu F. Wright ◽  
Edward R. Brand ◽  
Margaret Ziomek-Moroz ◽  
Joseph H. Tylczak ◽  
Paul R. Ohodnicki
Keyword(s):  
Carbon Steel ◽  
Steel Corrosion ◽  
Electrochemical Kinetics ◽  
Kinetics Of

The environmental impact of rock support for road tunnels: The experience of Norway

2020 ◽  
Vol 712 ◽  
pp. 136421
Author(s):  
Lizhen Huang ◽  
Pål Drevland Jakobsen ◽  
Rolf André Bohne ◽  
Yongping Liu ◽  
Amund Bruland ◽  
...  
Keyword(s):  
Environmental Impact ◽  
Rock Support ◽  
Road Tunnels

Kinetics of enzymatic O-methylation: its value in assays for catecholamines in plasma.

1984 ◽  
Vol 30 (1) ◽  
pp. 24-27 ◽  
Author(s):  
L Mason ◽  
C Weinkove
Keyword(s):  
Mathematical Analysis ◽  
Plasma Catecholamines ◽  
High Concentration ◽  
Internal Standards ◽  
Linear Approximations ◽  
Endogenous Catecholamine ◽  
Radioenzymatic Assay ◽  
Exponential Equations ◽  
Kinetics Of ◽  
Catecholamine Concentration

Abstract The kinetics of enzymatic O-methylation of catecholamines were studied under conditions like those used in the radioenzymatic assay of plasma catecholamines. Inappropriate Michaelis-Menten kinetics and linear approximations of exponential equations were not used. Mathematical analysis indicated the importance of the ratio of methyl donor (S-adenosylmethionine) to substrate (catecholamine) concentration. If the reaction is incomplete, only a large ratio will allow linear approximations between product formed and initial catecholamine concentration. The use of high-concentration internal standards to correct for plasma interference may give erroneous results by reducing this ratio. Accuracy will be improved by ensuring (a) that S-adenosylmethionine is always greatly in excess of catecholamine, (b) that concentrations of added standards are of the same order as for endogenous catecholamine, and (c) that a high activity of enzyme is used, to allow the reaction to reach completion even in the presence of some inhibition.

Sign in / Sign up

Export Citation Format

Share Document