Collapse of cohesive overburden following removal of support

W. H. Craig

doi:10.1139/t90-046

Collapse of cohesive overburden following removal of support

Canadian Geotechnical Journal ◽

10.1139/t90-046 ◽

1990 ◽

Vol 27 (3) ◽

pp. 355-364 ◽

Cited By ~ 20

Author(s):

W. H. Craig

Keyword(s):

Critical Diameter ◽

Extraction Process ◽

Void Size ◽

Critical Stability ◽

Constant Acceleration ◽

Turn On ◽

Centrifuge Models ◽

Critical Void ◽

Bound Analysis ◽

Material Extraction

Model tests have been performed in a large centrifuge to investigate the conditions for critical stability of a circular cavity formed by removal of underlying support strata beneath a soft to very soft cohesive overburden. Initial tests used a fixed geometry and were subjected to increasing self-weight by the "gravity turn-on" technique, while later tests utilized a dynamic material extraction process at constant acceleration levels. The mechanics of failure are described and a simple upper-bound analysis is found to predict the critical void size within acceptable limits for a range of the ratio of overburden depth to critical diameter from 0.5 to 1.5. Key words: cohesive overburden, stability, centrifuge, models, voids.

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Fatal Void Size Comparisons in Via-Below and Via-Above Cu Dual-Damascene Interconnects

MRS Proceedings ◽

10.1557/proc-812-f7.6 ◽

2004 ◽

Vol 812 ◽

Cited By ~ 3

Author(s):

Z. -S. Choi ◽

C. L. Gan ◽

F. Wei ◽

C. V. Thompson ◽

J. H. Lee ◽

...

Keyword(s):

Numerical Simulation ◽

Failure Mechanisms ◽

Simulation Tool ◽

Void Size ◽

Dual Damascene ◽

Preferential Nucleation ◽

Failure Correlation ◽

Void Volumes ◽

Damascene Interconnects ◽

Critical Void

AbstractThe median-times-to-failure (t50's) for straight dual-damascene via-terminated copper interconnect structures, tested under the same conditions, depend on whether the vias connect down to underlaying leads (metal 2, M2, or via-below structures) or connect up to overlaying leads (metal 1, M1, or via-above structures). Experimental results for a variety of line lengths, widths, and numbers of vias show higher t50's for M2 structures than for analogous M1 structures. It has been shown that despite this asymmetry in lifetimes, the electromigration drift velocity is the same for these two types of structures, suggesting that fatal void volumes are different in these two cases. A numerical simulation tool based on the Korhonen model has been developed and used to simulate the conditions for void growth and correlate fatal void sizes with lifetimes. These simulations suggest that the average fatal void size for M2 structures is more than twice the size of that of M1 structures. This result supports an earlier suggestion that preferential nucleation at the Cu/Si3N4 interface in both M1 and M2 structures leads to different fatal void sizes, because larger voids are required to span the line thickness in M2 structures while smaller voids below the base of vias can cause failures in M1 structures. However, it is also found that the fatal void sizes corresponding to the shortest-times-to-failure (STTF's) are similar for M1 and M2, suggesting that the voids that lead to the shortest lifetimes occur at or in the vias in both cases, where a void need only span the via to cause failure. Correlation of lifetimes and critical void volumes provides a useful tool for distinguishing failure mechanisms.

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Consecutive and progressive purification of food-derived natural polysaccharide: Based on material, extraction process and crude polysaccharide

Trends in Food Science & Technology ◽

10.1016/j.tifs.2020.02.015 ◽

2020 ◽

Vol 99 ◽

pp. 76-87 ◽

Cited By ~ 5

Author(s):

Wei Tang ◽

Dan Liu ◽

Jun-Yi Yin ◽

Shao-Ping Nie

Keyword(s):

Extraction Process ◽

Natural Polysaccharide ◽

Crude Polysaccharide ◽

Material Extraction

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ZAT WARNA DARI GETAH TANGKAI DAUN PISANG (MUSA SSP.)

EKUILIBIUM ◽

10.20961/ekuilibrium.v14i2.2042 ◽

2015 ◽

Vol 14 (2) ◽

Author(s):

Paryanto Paryanto

Keyword(s):

Rotational Speed ◽

Extraction Process ◽

Natural Dye ◽

Solvent Ratio ◽

Optimum Conditions ◽

Total Level ◽

Banana Leaf ◽

Banana Stem ◽

Material Extraction ◽

Brown Color

Abstract: One of the natural dye sources for the brown color called tannins is Resin Banana Leaf Stem. Tannins were obtained through the extraction process of Resin Banana Leaf Stem using 96% ethanol. This study aimed to obtain a total level by extraction and drying. The influence of the material with a solvent ratio (weight/volume), time, temperature, and rotational speed stirrer in the extraction of dye from resin stem of banana were studied to get an optimum process. This experiment is using some ratios of the weight of banana leaf to the volume of solvent, i.e.: 20:200 and 50:200 (g/ml). The condition was set at 63 C for 160 minutes and stirring rotational speed of 200 rpm. With the same material, extraction with soxhlet was done until the solvent becomes clear. Total tannin was obtained at 7.68%. With a three-neck flask extraction process obtained the optimum conditions, i.e.: the ratio of the weight to the volume of solvent of 50:200 g/ml at 63 o o C, and stirring rotational speed of 200 rpm for 140 minutes. This condition process produce heavy tannins about 29.2576 mg. Keywords: banana stem, resin, extraction, natural dye

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TENSILE FAILURE OF SINGLE-CRYSTAL AND NANOCRYSTALLINE LENNARD-JONES SOLIDS UNDER UNIAXIAL STRAIN

International Journal of Modern Physics C ◽

10.1142/s0129183106010017 ◽

2006 ◽

Vol 17 (11) ◽

pp. 1551-1561 ◽

Cited By ~ 8

Author(s):

SHENG-NIAN LUO ◽

LIANQING ZHENG ◽

QI AN ◽

SHIJIN ZHAO

Keyword(s):

Single Crystal ◽

Grain Boundaries ◽

Void Nucleation ◽

Void Formation ◽

Stacking Faults ◽

Uniaxial Strain ◽

Tensile Failure ◽

Void Size ◽

Lennard Jones ◽

Critical Void

We investigate using molecular dynamics, the tensile failure of single-crystal and nanocrystalline Lennard-Jones solids under uniaxial strain. Stresses are relaxed by plasticity and tensile failure, which are induced via stacking faults, twin planes, void nucleation and growth, and their interactions. Stacking faults and twin planes as well as multiple nanovoids are nucleated at grain boundaries in a nanocrystalline solid. Void formation is characterized by under-coordinated atoms with coordination number ≤ 7, and the critical void size is comparable to a vacancy. For a single crystal, the number of stacking faults and twin planes decreases during failure mostly due to the absorption by nanovoids. In contrast, it increases with strain monotonically for a nanocrystalline solid, where abundant grain boundaries help the nucleation and deter the propagation and absorption of the stacking faults and twin planes, inducing effective dislocation pile-ups at grain boundaries even in the presence of nanovoids.

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Optimization of Operating Conditions of Essential Oil Extraction of Vietnamese Pomelo (Citrus grandis L.) Peels by Hydrodistillation Process

Asian Journal of Chemistry ◽

10.14233/ajchem.2020.22179 ◽

2019 ◽

Vol 32 (2) ◽

pp. 237-243 ◽

Cited By ~ 3

Author(s):

Tan Phat Dao ◽

Ngo Thi Cam Quyen ◽

Thien Hien Tran ◽

Pham Van Thinh ◽

Pham Quoc Long ◽

...

Keyword(s):

Essential Oil ◽

Extraction Process ◽

Operating Conditions ◽

Gas Chromatography Mass Spectrometry ◽

Optimal Conditions ◽

Predicted Values ◽

Main Component ◽

Influential Parameters ◽

Central Composite ◽

Material Extraction

This study attempted the optimization of the extraction process involving essential oils from Vietnamese pomelo fruits. Three influential parameters including ratio of water and material, extraction time, and temperature were assumed to be impactful to the oil yield and were investigated by establishing a statistical model. A central composite design was adopted to generate dataset required for estimation of the model. Analysis of variance was used to calculate model significance. The results showed that optimum yield of pomelo oil is 4.46 % (v/w) corresponding to water ratio of 507 mL water to 100 g sample, temperature at 119.29 ºC and distillation time of 113.68 min. Predicted values proposed by the Design Expert 11 software well-agreed with the empirical data, suggesting the excellent predictability of the proposed models. In addition, the essential oil obtained under optimal conditions was analyzed by gas chromatography-mass spectrometry. The results indicated that D-limonene is the main component (97.318 %) of essential oil.

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Freeze-Etch Crystal-Like Structures in Membranous Glomerulosclerosis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100063883 ◽

1969 ◽

Vol 27 ◽

pp. 394-395

Author(s):

Burton B. Silver

Keyword(s):

Electron Microscopy ◽

Light Microscopy ◽

Sodium Hypochlorite ◽

Kidney Tissue ◽

Extraction Process ◽

Donor Kidney ◽

Unknown Substance ◽

Etched Surface ◽

Standard Fixation ◽

Diseased Kidney

Tissue from a non-functional kidney affected with chronic membranous glomerulosclerosis was removed at time of trnasplantation. Recipient kidney tissue and donor kidney tissue were simultaneously fixed for electron microscopy. Primary fixation was in phosphate buffered gluteraldehyde followed by infiltration in 20 and then 40% glycerol. The tissues were frozen in liquid Freon and finally in liquid nitrogen. Fracturing and replication of the etched surface was carried out in a Denton freeze-etch device. The etched surface was coated with platinum followed by carbon. These replicas were cleaned in a 50% solution of sodium hypochlorite and mounted on 400 mesh copper grids. They were examined in an Siemens Elmiskop IA. The pictures suggested that the diseased kidney had heavy deposits of an unknown substance which might account for its inoperative state at the time of surgery. Such deposits were not as apparent in light microscopy or in the standard fixation methods used for EM. This might have been due to some extraction process which removed such granular material in the dehydration steps.

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Ubiquinone-BODIPY nanoparticles for tumor redox-responsive fluorescence imaging and photodynamic activity

Journal of Materials Chemistry B ◽

10.1039/d0tb02529a ◽

2021 ◽

Author(s):

Byunghee Hwang ◽

Tae-Il Kim ◽

Hyunjin Kim ◽

Sungjin Jeon ◽

Yongdoo Choi ◽

...

Keyword(s):

Fluorescence Imaging ◽

Selective Activation ◽

Turn On ◽

Intracellular Environment ◽

Redox Responsive ◽

Photodynamic Activity

A ubiquinone-BODIPY photosensitizer self-assembles into nanoparticles (PS-Q-NPs) and undergoes selective activation within the highly reductive intracellular environment of tumors, resulting in “turn-on” fluorescence and photosensitizing activities.

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