Effects of fire on cation content in water: a laboratory simulation study

2013 ◽  
Vol 22 (5) ◽  
pp. 667 ◽  
Author(s):  
J. Cancelo-González ◽  
M. E. Rial-Rivas ◽  
F. Díaz-Fierros
Keyword(s):  
Thermal Shock ◽  
Divalent Cations ◽  
Monovalent Cation ◽  
Laboratory Simulation ◽  
Exchangeable Cation ◽  
Simulated Rainfall ◽  
Rainfall Events ◽  
Cation Leaching ◽  
Monovalent Ions ◽  
Thermal Shocks

Laboratory experiments were carried out to explore the effect of thermal shocks (as occur during fire) and simulated rainfall events on cation leaching dynamics in an organic rich Leptic Umbrisol soil. The soil samples were collected in the field using specially designed lysimeter boxes that allow sampling and application of thermal shock treatments and simulated rainfall while keeping the soil structure unaltered. The soil temperature during the thermal shocks and degree-hours of accumulated heat were determined, and cation (Na+, K+, Ca2+ and Mg2+) leaching was measured in surface runoff (0-cm depth) and subsurface flow (12-cm depth) samples collected from the lysimeter boxes. Important differences were found in cation leaching in relation to thermal shock: monovalent cation leaching from the soil above 200°C (68 degree-hours) and divalent cations leaching above 220°C (195 degree-hours) was higher than that seen in other treatments. In general, the amount of cations leached increased with the severity of the thermal shock; however, under moderate conditions, there was a decrease in cation leaching, mainly of monovalent ions. The exchangeable cation losses by leaching in the intense heat treatments were ~80%.

Board-Level Reliability of Pb-Free Surface Mounted Assemblies during Thermal Shock Testing

2006 ◽  
Vol 15-17 ◽  
pp. 633-638 ◽  
Author(s):  
Jong Woong Kim ◽  
Hyun Suk Chun ◽  
Sang Su Ha ◽  
Jong Hyuck Chae ◽  
Jin Ho Joo ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Solder Joints ◽  
Lead Frame ◽  
Shear Forces ◽  
Microstructural Investigation ◽  
Shock Testing ◽  
Ceramic Capacitor ◽  
Board Level ◽  
Board Level Reliability ◽  
Thermal Shocks

Board-level reliability of conventional Sn-37Pb and Pb-free Sn-3.0Ag-0.5Cu solder joints was evaluated using thermal shock testing. In the microstructural investigation of the solder joints, the formation of Cu6Sn5 intermetallic compound (IMC) layer was observed between both solders and Cu lead frame, but any crack or newly introduced defect cannot be found even after 2000 cycles of thermal shocks. Shear test of the multi layer ceramic capacitor (MLCC) joints were also conducted to investigate the effect of microstructural variations on the bonding strength of the solder joints. Shear forces of the both solder joints decreased with increasing thermal shock cycles. The reason to the decrease in shear force was discussed with fracture surfaces of the shear tested solder joints.

scholarly journals Self-assembly of highly ordered DNA origami lattices at solid-liquid interfaces by controlling cation binding and exchange

Nano Research ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 3142-3150 ◽  
Author(s):  
Yang Xin ◽  
Salvador Martinez Rivadeneira ◽  
Guido Grundmeier ◽  
Mario Castro ◽  
Adrian Keller
Keyword(s):  
Correlation Length ◽  
Self Assembly ◽  
High Speed ◽  
Time Course ◽  
Divalent Cations ◽  
Topological Analysis ◽  
Monovalent Cation ◽  
Cation Binding ◽  
Dna Origami ◽  
Lattice Order

Abstract The surface-assisted hierarchical self-assembly of DNA origami lattices represents a versatile and straightforward method for the organization of functional nanoscale objects such as proteins and nanoparticles. Here, we demonstrate that controlling the binding and exchange of different monovalent and divalent cation species at the DNA-mica interface enables the self-assembly of highly ordered DNA origami lattices on mica surfaces. The development of lattice quality and order is quantified by a detailed topological analysis of high-speed atomic force microscopy (HS-AFM) images. We find that lattice formation and quality strongly depend on the monovalent cation species. Na+ is more effective than Li+ and K+ in facilitating the assembly of high-quality DNA origami lattices, because it is replacing the divalent cations at their binding sites in the DNA backbone more efficiently. With regard to divalent cations, Ca2+ can be displaced more easily from the backbone phosphates than Mg2+ and is thus superior in guiding lattice assembly. By independently adjusting incubation time, DNA origami concentration, and cation species, we thus obtain a highly ordered DNA origami lattice with an unprecedented normalized correlation length of 8.2. Beyond the correlation length, we use computer vision algorithms to compute the time course of different topological observables that, overall, demonstrate that replacing MgCl2 by CaCl2 enables the synthesis of DNA origami lattices with drastically increased lattice order.

scholarly journals Cryogenic Fracturing of Wellbores Under True Triaxial-Confining Stresses: Experimental Investigation

SPE Journal ◽  
2018 ◽  
Vol 23 (04) ◽  
pp. 1271-1289 ◽  
Author(s):  
Minsu Cha ◽  
Naif B. Alqahtani ◽  
Bowen Yao ◽  
Xiaolong Yin ◽  
Timothy J. Kneafsey ◽  
...  
Keyword(s):  
High Pressure ◽  
Thermal Shock ◽  
Principal Stress ◽  
Breakdown Pressure ◽  
True Triaxial ◽  
Pressure Decay ◽  
Stress Levels ◽  
Cryogenic Fracturing ◽  
Flow Through ◽  
Thermal Shocks

Summary A laboratory study of cryogenic fracturing was performed to test its ability to improve oil/gas recovery from low-permeability reservoirs. Our objective is to develop well-stimulation technologies using cryogenic fluids [e.g., liquid nitrogen (LN)] to increase permeability in a large reservoir volume surrounding wells. The new technology has the potential to reduce formation damage caused by current stimulation methods and minimize or eliminate water usage. The concept of cryogenic fracturing is that a sharp thermal gradient (thermal shock) created at the surfaces of formation rocks by applying cryogenic fluid can cause strong local tensile stress and start fractures. We developed a laboratory system for cryogenic fracturing under true-triaxial loading, with LN-delivery/control and -measurement systems. The loading system simulates confining stresses by independently loading each axis up to approximately 5,000 psi on 8×8×8-in. cubes. Temperature in boreholes and at block surfaces and fluid pressure in boreholes were continuously monitored. Acoustic and pressure-decay measurements were obtained before and at various stages of stimulations. Cubic blocks (8 × 8×8-in.) of Niobrara shale, concrete, and sandstones were tested, and stress levels and anisotropies varied. Three schemes were considered: gas fracturing without cryo-stimulation, gas fracturing after low-pressure cryogen flow-through, and gas fracturing after high-pressure cryogen flow-through. Results from pressure-decay tests show that LN stimulation clearly increases permeability, and repeated stimulations further increase the permeability. Acoustic velocities and amplitudes decreased significantly after cryo-stimulation, indicating fracture creation. In the gas fracturing without the stimulation, breakdown (complete fracturing) occurs suddenly without any initial leaking, and major fracture planes form along the plane containing principal-stress and intermediate-stress directions, as expected theoretically. However, in the gas fracturing after cryogenic stimulations, breakdown occurred gradually and with massive leaking because of thermal fractures created during stimulation. In addition, the major fracture direction does not necessarily follow the plane containing the principal-stress direction, especially at low confining-stress levels. In tests, we observed that cryogenic stimulation seems to disrupt the internal stress field. The increase in borehole temperature after stimulation affects the permeability of the specimen. When a stimulated specimen is still cold, it maintains high permeability because fractures remain open and local thermal tension is maintained near the borehole. When the rock warms back, fractures close and permeability decreases. In these tests, we have not used proppants. Overall, fractures are clearly generated by low- and high-pressure thermal shocks. The added pressure of the high-pressure thermal shocks helps to further propagate cryogenic fractures generated by thermal shock. Breakdown pressure is significantly lowered by LN stimulation, with observed breakdown-pressure reductions up to approximately 40%.

Changes in extractable and microbial C, N, and P in a Western Australian wheatbelt soil following simulated summer rainfall

Soil Research ◽  
1998 ◽  
Vol 36 (5) ◽  
pp. 841 ◽  
Author(s):  
A. M. McNeill ◽  
G. P. Sparling ◽  
D. V. Murphy ◽  
P. Braunberger ◽  
I. R. P. Fillery
Keyword(s):  
Organic N ◽  
Land Uses ◽  
Simulated Rainfall ◽  
Soil Extracts ◽  
Rainfall Events ◽  
Olsen P ◽  
Significant Difference ◽  
C And N ◽  
Microbial C ◽  
Western Australian

The effects of simulated rainfall events during the summer fallow period on extractable and microbial carbon (C), nitrogen (N), and phosphorus (P) in soils under either continuous wheat or the second-year pasture phase of a 2-pasture-1-wheat rotation in the Western Australian wheatbelt were investigated. A ‘single wetting’ treatment (45 mm rainfall on Day 0) was compared with a 55 mm ‘multiple wetting’ treatment (45 mm at Day 0, 5 mm at Day 3, and 5 mm at Day 8). Soil samples from 0{10 cm depth were taken prior to, and at regular intervals up to 14 days following, the inital wetting event. Soil extracts were assayed for total soluble N (TSN), total oxidisable C (TOC), Olsen-P, and ninhydrin-positive compounds (NPC). Prior to the simulated rainfall events, extractable TSN and TOC in the air-dry fallow soils were significantly higher (P < 0·01), and Olsen-P significantly lower, for the pasture land use compared with the continuous wheat. However, subsequent to wetting there were no significant differences between the 2 land uses, or single and multiple wetting treatments, for extractable TSN, TOC, Olsen P, or NPC. Extractable soluble organic N (SON), calculated by subtracting measured inorganic N from TSN, decreased within 48 h of each wetting event to a minimal value but, after the first 2 wetting events, subsequently increased to at least the prewet value. Microbial C, N, and P were estimated from the difference in TOC, TSN, and Olsen-P of extracts from fumigated and unfumigated soils (microbial ‘flush’) and microbial C and N were also estimated from the NPC ‘flush’. There was generally good agreement between the 2 estimates of microbial N (NPC and TSN, R2 = 0·50), but less so for the 2 estimates of microbial C (NPC and TOC, R2 = 0 ·31). There was no significant difference in microbial C, N, or P between the 2 land uses, but there was a highly significant response of the microbial biomass to wetting events and also significant differences in temporal patterns between the single and multiple wetting treatments. Microbial C and N increased in the period following initial wetting, more rapidly in the wheat than the pasture, reaching a peak at Day 2 for wheat and Day 3 for pasture. Subsequently, for the single wet treatment, there was a steady linear decline in microbial C and N until Day 10, whereas over the same period (Days 4-10) in the multiple wet treatment there were 2 highly significant quadratic responses to time, manifest as a linear increase in microbial C and N following each re-wetting event, to a peak value 24 h after the event, and a subsequent decline to the pre-wet value after a further 24 h.

scholarly journals Investigation of the Effect of Operational Factors on Conveyor Belt Mechanical Properties

2020 ◽  
Vol 10 (12) ◽  
pp. 4201
Author(s):  
Anna Rudawska ◽  
Radovan Madleňák ◽  
Lucia Madleňáková ◽  
Paweł Droździel
Keyword(s):  
Mechanical Properties ◽  
Thermal Shock ◽  
Tensile Modulus ◽  
Conveyor Belt ◽  
Specific Humidity ◽  
Climatic Chamber ◽  
Strength Parameters ◽  
Shock Chamber ◽  
Operational Factors ◽  
Thermal Shocks

This paper aims to present the effect of specific operational factors (temperature and humidity) on the selected mechanical properties of a conveyor belt. The tests were conducted in a climatic chamber, simulating the effect of both minus and plus temperatures −30 °C to 80 °C (243 K to 353 K) at specific humidity, and in a thermal shock chamber where a varying number of ageing cycles was applied for a specific range of thermal shocks. Six different tests in the climatic chamber and four different tests in a thermal shock chamber were conducted. The results of the climatic chamber tests demonstrate that many strength parameters have undesired values at a temperature of 10 °C (283 K) and 80 °C (353 K) at a relative humidity of 80%. Interestingly, the results revealed that tensile strength, tensile modulus and yield strength are higher at below 0 °C temperature than at above 0 °C temperature. For example, comparing the temperature −30 °C (243 K) and +30 °C (303 K) obtained a difference of tensile modulus of nearly 10%, and comparing the temperature −30 °C (243 K) and +10 °C (283 K) the differences were 22%.

Evaluation of the Thermal Shock Fatigue Resistance of Cutting Tools Using a CO2 Pulse Laser Beam

2016 ◽  
Vol 719 ◽  
pp. 109-113
Author(s):  
Kenji Yamaguchi ◽  
Itaru Matsumoto ◽  
Tsuyoshi Fujita ◽  
Yasuo Kondo ◽  
Satoshi Sakamoto ◽  
...  
Keyword(s):  
Laser Beam ◽  
Thermal Shock ◽  
Pulse Laser ◽  
Fatigue Resistance ◽  
High Speed ◽  
Evaluation Method ◽  
Cutting Tools ◽  
Pulse Laser Beam ◽  
Intermittent Cutting ◽  
Thermal Shocks

It is well-known that a series of cracks sometimes gets initiated perpendicular to the cutting edges on the rake faces of brittle cutting tools made of materials such as cemented carbide, ceramics, and cermet under high-speed intermittent cutting. The tools used in intermittent cutting processes are exposed to elevated temperatures during cutting and then cool quickly during the noncutting time. Previous studies have suggested that such repeated thermal shocks generate thermal stress in the tool and that the thermal cracks are then propagated by thermal fatigue. Recently, high-speed machining techniques have attracted the attention of researchers. To apply new cutting tool materials to this machining process, it is important to evaluate their thermal shock fatigue resistances. During high-speed intermittent cutting, the frequency of thermal shocks becomes high and the action area of the thermal shocks is limited to the rake face of the tool. Therefore, conventional thermal shock resistance evaluation methods are unsuitable for this case. Consequently, the authors have developed a new experimental evaluation method using a CO2 laser beam. In this study, we irradiated cemented carbide and TiN cermet cutting tools with the CO2 pulse laser beam and gauged the effectiveness of the proposed thermal shock fatigue resistance evaluation method. The results show a correlation between the thermal shock due to the CO2 pulse laser beam and those due to the intermittent cutting experiments.

scholarly journals Comparative Study of the Thermal Shock Resistance of an Industrial Tableware Porcelain

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
Habib Sahlaoui ◽  
Kamel Makhlouf ◽  
Habib Sidhom
Keyword(s):  
Low Temperature ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Mechanical Resistance ◽  
Firing Cycle ◽  
Bending Tests ◽  
Three Point Bending ◽  
Shock Resistance ◽  
Silica Ratio ◽  
Thermal Shocks

The effect of the glazed layer and firing conditions (temperature and duration) on the thermal shocks behavior of tableware porcelains has been studied. Two types of glazed layers and three firing conditions, used industrially in the commercial porcelains manufacture, are used in this investigation. Repeated thermal shock tests showed that the glazed layer with higher alumina/silica ratio is more resistant to thermal shocks and that the slow firing cycle, even at a relatively low temperature, is very beneficial for the thermal shock resistance of the porcelain matrix. Three-point bending tests showed that the crazing phenomenon, which affects the glazed layers as well as the porcelain matrix, does not affect significantly the mechanical resistance of these materials.

scholarly journals Timing and conditions modify the effect of structure liming on clay soil

2021 ◽  
Author(s):  
Jens Erik Blomquist ◽  
Kerstin Berglund
Keyword(s):  
Clay Soil ◽  
Aggregate Stability ◽  
Aggregate Size ◽  
Soil Conditions ◽  
Simulated Rainfall ◽  
Rainfall Events ◽  
Inner Diameter ◽  
One Year ◽  
Stability Measurements ◽  
Effect Of Structure

Two dates (early, normal) for application and incorporation of structure lime to clay soil were examined at four field sites, to test whether early liming had more favourable effects on aggregate stability. Aggregate size distribution measurements revealed a finer tilth at the early liming date (20 August) than the normal date (14 September). Aggregate stability estimated one year later, using as a proxy turbidity in leachate from 2–5 mm aggregates subjected to two simulated rainfall events, was significantly improved (11% lower turbidity) with early compared with normal liming date. Three years after structure liming, soil structural stability measurements on lysimeters (15 cm high, inner diameter 18 cm) subjected to repeated simulated rainfall events showed no significant differences in turbidity in leachate between the early and normal liming dates. However, there was a strong interaction between liming date and site indicating different reactions at different sites. Our results suggest that early spreading and incorporation can improve the success of structure liming, but only if soil conditions are favourable.

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