1,339 research outputs found
X-ray micro-CT imaging of abiotic calcium carbonate cementation in sand and its effect on hydraulic conductivity
No full textReductions in Hydraulic Conductivity of Sands Caused by Microbially Induced Calcium Carbonate Precipitation
No full textMicrobially induced calcite precipitation (MICP) modifies soil behavior and properties through the precipitation of calcium carbonate (CaCO3) in the pore space. It has gained prominence as one strategy for biologically induced soil improvement. This study investigates the effect of MICP on hydraulic conductivity reduction and presents permeability reduction models for MICP-treated sands. Four column experiments, each with a different size of poorly graded sand, were subject to low-concentration equimolar MICP treatments while monitoring hydraulic conductivity reduction and precipitated CaCO3 distribution. Multiple MICP treatments produced homogeneous distributions of CaCO3 and caused a gradual reduction in hydraulic conductivity of 50%-90% until a CaCO3 content of similar to 10%-15% was achieved. The high-resolution X-ray computed microtomography (CMT) and scanning electron microscopy (SEM) imaging reveals that the pore-scale precipitation behavior changes from a contact-cementing pattern in fine sands to a mixed pattern of contact-cementing and surface-coating precipitation in coarse sands as the grain size increases. The Kozeny-Carman type of permeability models appear to well capture the hydraulic conductivity reduction caused by MICP as a function of volumetric pore fraction of CaCO3. The experimental results presented in this study advance our understanding of the pore-scale CaCO3 precipitation patterns in different sizes of sands and their effect on hydraulic conductivity. Additionally, this study provides unique and reliable hydraulic conductivity data that can be used to develop hydraulic conductivity models for MICP-treated sands.
Radiographic Measurements Associated With Ankle Power Generation During Gait in Patients With Cerebral Palsy
No full textBackground:Pes planovalgus (PV) deformity accounts for lever arm dysfunction and compromises gait in patients with cerebral palsy (CP). However, the association between ankle power generation and radiographic indices is not yet understood. We aimed to investigate the association between ankle power and radiographic indices during gait in patients with CP concomitant with PV deformity.Methods:Patients older than 14 years with ambulatory CP and PV deformity were included. All the patients underwent 3-dimensional gait analysis and weight-bearing foot radiography. Gait data were collected, including foot progression angle, tibial rotation, hip rotation, and ankle power generation. Radiographic measurements included anteroposterior (AP) talo-first metatarsal angle, lateral talo-first metatarsal angle, and hindfoot angle. A linear mixed-effects model was performed to identify significant radiographic indices associated with ankle power generation.Results:Thirty-one limbs from 15 patients with spastic diplegia and 6 with spastic hemiplegia were included. Statistical analysis demonstrated that ankle power generation was significantly correlated with the CP type (P=0.0068) and AP talo-1st metatarsal angle (P=0.0230).Conclusion:Ankle power generation was significantly associated with the AP talo-first metatarsal angle. Surgeons might need to pay attention to correcting forefoot abduction to restore ankle power when planning surgeries for pes PV deformities in patients with CP.Level of Evidence:Prognostic Level III
sj-docx-1-tan-10.1177_17562864231218181 – Supplemental material for Effect of altered gene expression in lipid metabolism on cognitive improvement in patients with Alzheimer’s dementia following fecal microbiota transplantation: a preliminary study
No full textSupplemental material, sj-docx-1-tan-10.1177_17562864231218181 for Effect of altered gene expression in lipid metabolism on cognitive improvement in patients with Alzheimer’s dementia following fecal microbiota transplantation: a preliminary study by Jun-Seob Kim, Hyelim Park, Jung-Hwan Lee, Jongbeom Shin, Boram Cha, Kye Sook Kwon, Yong Woon Shin, Yerim Kim, YeoJin Kim, Jong Seok Bae, Ju-Hun Lee, Seok-Jin Choi, Tae Jung Kim, Sang-Bae Ko and Soo-Hyun Park in Therapeutic Advances in Neurological Disorders</p
Highly entangled hollow TiO2 nanoribbons templating diphenylalanine assembly
No full textWe introduce a biotemplating approach for creating highly entangled hollow TiO2 nanoribbons by combining peptide assembly with an atomic layer deposition process. An aromatic peptide of diphenylalanine was readily assembled into a hierarchical organogel consisting of highly entangled nanoribbons. Unlike ordinary biomaterials, the peptide nanoribbon framework exhibited a high level of thermal stability, such that it may undergo the further functionalization process of vacuum deposition without significant damage to its nanoscale structure. A nanoscale layer of anatase TiO2 was deposited on the nanoribbon framework by means of atomic layer deposition. After pyrolysis, a highly entangled nanotubular TiO2 framework was created successfully. The highly entangled TiO2 architecture exhibited UV-switchable wetting properties.This work was supported by the second stage of the Brain
Korea 21 Project, National Research Laboratory Program
(R0A-2008-000-20057-0), the KAIST EEWS Initiative (No.
EEWS0903, EEWS: Energy, Environment, Water, and
Sustainability), the Fundamental R&D Program for Core
Technology of Materials, and the National Core Research
Center Program (R15-2006-022-01001-0) funded by the Korean
government
Mineral Trapping on Permeability
No full textAbiotic carbonate precipitation has garnered significant interest as a mechanism for mineral trapping of carbon dioxide (CO2) in geologic carbon storage, as a natural diagenetic process frequently occurring in marine environments, and as an engineering approach for soil improvement. This study explored pore-scale precipitation of calcium carbonate (CaCO3) and its effect on the permeability of porous media, using X-ray computed microtomography (CMT). In a column experiment, CaCO3 was precipitated in a sand pack from a supersaturated CaCO3 solution, while porosity, pore volume fraction of carbonate, and permeability were being monitored and X-ray CMT images were being acquired. Permeability reduction by similar to 99.94% was observed when precipitated carbonate occupied similar to 46-47% of pore volume. The X-ray CMT images showed that carbonate crystals were initially nucleated onto sand grain surfaces, which facilitated subsequent precipitation, indicating a predominantly grain-coating behavior. The scanning electron microscopy revealed the carbonate crystals of similar to 1-20 mu m in size and the presence of internal pores in the carbonate layers at the submicrometer scale. Variations in carbonate layer thickness and geometric tortuosity, and preferential carbonate precipitation behavior with local clogging were examined through morphological analysis and phase segmentation. Particularly, the pore-scale precipitation pattern and hence the pore geometry were found to evolve with continued precipitation from a grain-coating behavior, through a pore-filling behavior, and finally into a dramatic pore-throat-clogging behavior. Our results provide unique experiment data for predictive modeling of long-term CO2 transport and provide new insights into the changes in physical and transport properties during CO2 mineral trapping.
sj-docx-1-wso-10.1177_17474930231158211 – Supplemental material for Optimal use of antithrombotic agents in ischemic stroke with atrial fibrillation and large artery atherosclerosis
No full textSupplemental material, sj-docx-1-wso-10.1177_17474930231158211 for Optimal use of antithrombotic agents in ischemic stroke with atrial fibrillation and large artery atherosclerosis by Tae Jung Kim, Ji Sung Lee, Jae Sun Yoon, Mi Sun Oh, Ji-Woo Kim, Soo-Hyun Park, Keun-Hwa Jung, Hyun Young Kim, Jee-Hyun Kwon, Hye-Yeon Choi, Hahn Young Kim, Kyung Yoon Eah, Sang Won Han, Hyung-Geun Oh, Young-Jae Kim, Byoung-Soo Shin, Chang Hun Kim, Chi Kyung Kim, Jong-Moo Park, Kyung Bok Lee, Tai Hwan Park, Jun Lee, Man-Seok Park, Jay Chol Choi, Chulho Kim, Dong-Ick Shin, Soo Joo Lee, Dong-Eog Kim, Jae-Kwan Cha, Eung-Gyu Kim, Kyung-Ho Yu, Keun-Sik Hong, Young-Seok Lee, Ju-Hun Lee, Sung Il Sohn, Hee-Joon Bae, Young-Bae Lee, Jun Hong Lee, Joung-Ho Rha, Byung-Chul Lee, Dae-Il Chang, Sang-Bae Ko and Byung-Woo Yoon in International Journal of Stroke</p
Ambient printing of native oxides for ultrathin transparent flexible circuit boards
No full textMetal oxide films are essential in most electronic devices, yet they are typically deposited at elevated temperatures by using slow, vacuum-based processes. We printed native oxide films over large areas at ambient conditions by moving a molten metal meniscus across a target substrate. The oxide gently separates from the metal through fluid instabilities that occur in the meniscus, leading to uniform films free of liquid residue. The printed oxide has a metallic interlayer that renders the films highly conductive. The metallic character of the printed films promotes wetting of trace amounts of evaporated gold that would otherwise form disconnected islands on conventional oxide surfaces. The resulting ultrathin (<10 nanometers) conductors can be patterned into flexible circuits that are transparent, mechanically robust, and electrically stable, even at elevated temperatures.
Hydrogen-Bond Free Energy of Local Biological Water
No full textHere, we propose an experimental methodology based on femtosecond???resolved fluorescence spectroscopy to measure the hydrogen (H)???bond free energy of water at protein surfaces under isothermal conditions. A demonstration was conducted by installing a non???canonical isostere of tryptophan (7???azatryptophan) at the surface of a coiled???coil protein to exploit the photoinduced proton transfer of its chromophoric moiety, 7???azaindole. The H???bond free energy of such biological water was evaluated by comparing the rates of the proton transfer, sensitive to the hydration environment, at the protein surface and in bulk water, and it was found to be higher than that of bulk water by 0.4 kcal/mol. The free???energy difference is dominated by the entropic cost in the H???bond network among water molecules at the hydrophilic and charged protein surface. Our study opens a door to accessing the energetics and dynamics of local biological water to give insight its roles in protein structure and function
Capitalizing on a Sport's Association with an International Destination: The Illustrative Example of Tae Kwon Do
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