• Steel and Composite Structures
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• v.31 no.1
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• pp.43-51
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• 2019

This paper is concerned with the numerical calculation of mixed-mode stress intensity factors (SIFs) of 2-D isotropic functionally graded materials (FGMs) by the natural element method (more exactly, Petrov-Galerkin NEM). The spatial variation of elastic modulus in non-homogeneous FGMs is reflected into the modified interaction integral ${\tilde{M}}^{(1,2)}$. The local NEM grid near the crack tip is refined, and the directly approximated strain and stress fields by PG-NEM are enhanced and smoothened by the patch recovery technique. Two numerical examples with the exponentially varying elastic modulus are taken to illustrate the proposed method. The mixed-mode SIFs are parametrically computed with respect to the exponent index in the elastic modulus and external loading and the crack angle and compared with the other reported results. It has been justified from the numerical results that the present method successfully and accurately calculates the mixed-mode stress intensity factors of 2-D non-homogeneous functionally graded materials.

• Food Science and Preservation
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• v.30 no.5
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• pp.785-796
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• 2023

The aim of this study was to elucidate chemical structures and rheological properties of arabinogalactans (AGs) isolated from three legumes including black gram (BG), great northern bean (GNB), and California small white bean (CSWB). The ratio of galactose to arabinose (G/A) in three legumes increased in the order of BG > GNB > CSWB. The rheological measurements of 1-5% (w/v) AG solutions revealed Newtonian and non-Newtonian flow behaviors. BG exhibited yield stress, indicating plastic behavior. Small-amplitude oscillatory tests indicated viscoelastic properties of BG, GNB, and CSWB ranging from solid-like, paste-like, and liquid-like behaviors, respectively. Small-strain oscillatory tests were conducted to assess the structure recovery of the AGs after pre-shearing. G" values of BG and GNB increased, but those of CSWB remained constant after shearing. These results suggest that the chemical structures of the AGs, particularly their G/A ratios, influence their rheological properties.

• Archives of Metallurgy and Materials
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• v.65 no.4
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• pp.1341-1344
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• 2020

In this study, a simple and effective way to fabricate highly porous scaffolds with controlled porosity and pore size is demonstrated. Ti-7Zr-6Sn-3Mo shape memory alloy fibers were prepared through a melt overflow process. The scaffolds with porosity of 65-85% and large pores of 100-700 ㎛ in size were fabricated by sintering the as-solidified fibers. Microstructures and transformation behaviors of the porous scaffolds were investigated by means of SEM, DSC and XRD. The scaffolds were composed of β phase at room temperature. Superelasticity with the superelastic recovery strain of 7.4% was achieved by β ↔ α" phase transformation. An effect of porosity on mechanical properties of porous scaffolds was investigated by using compressive test. As the porosity increased from 65% to 85%, elastic modulus and compressive strength decreased from 0.95 to 0.06 GPa and from 27 to 2 MPa, respectively.

• Journal of Life Science
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• v.27 no.5
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• pp.591-599
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• 2017

It is well established that endurance performance is negatively affected by environmental heat stress. Numerous scientific investigations have attempted to improve performance in the heat with pre-cooling and per-cooling for endurance athletes. Some cooling strategies are more logistically challenging than others, and thus are often impractical for use in training or competition. The purpose of this study was to review the literature on the use of cooling interventions in the improvement of performance and recovery from exercise-induced heat stress. We undertook an examination that focused on the effects of pre-cooling and per-cooling on the improvement in endurance performance and the effects of post-exercise cooling on recovery. The benefits for pre-cooling and per-cooling strategies undertaken in the laboratory setting could be employed by athletes who compete in hot environmental conditions to improve performance. Most laboratory studies have shown improvements in endurance performance following pre-cooling and per-cooling, and in recovery following post-cooling. Cooling strategies such as cooling vest, neck cooling collar, menthol and ice slurry are practically relevant to sports field. Cooling interventions that can be applied frequently to reduce thermal strain prior to, during and directly after training appear to be the best effective strategy to improve performance and recovery. Future research is warranted to investigate the effectiveness of practical pre-cooling and per-cooling strategies in competition or field settings.

• Korean Journal of Clinical Laboratory Science
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• v.51 no.2
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• pp.164-170
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• 2019

The absorption and release capacities, survival efficiency, and recovery rates of five kinds of transport media were evaluated based on the swab elution method (Quantitative) of CLSI (Clinical and Laboratory Standards Institute) M40-A2. Liquid media showed mostly better results than semi-solid media in the three evaluations. The flocked swabs had better ability to absorption and discharge bacteria than the standard swabs. The liquid medium (S4) had the best survival efficiency. Pneumococcal strains with poor growth had a higher survival efficiency and recovery rate in liquid media (S4, S5). The results of microbial recovery showed that S. pyogenes met all the CLSI standards in all media. S. pneumoniae was inadequate in the semi- solid media (S2, S3) and all the remaining media met the criteria. H. influenzae was unsuitable in semi-solid media (S1, S3) and met the criteria in semi-solid medium (S2) and liquid medium (S4, S5). The viability of the H. influenzae, pneumococcal strain causing respiratory disease, was poor in most media. Overgrowth of P. aeruginosa was observed at room temperature. The combination of liquid medium and flocked swab confirmed the best results in the three evaluation methods.

• Applied Biological Chemistry
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• v.37 no.1
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• pp.14-18
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• 1994

In order to elucidate the interaction effect between temperature and moisture content on the oil expression of perilla seed, recovery of expressed oil (REO) and volumetric strain of pressed cake (VSPC) of both roasted and unroasted perilla seeds were observed at different temperatures of 30, 40, 50 and $60^{\circ}C$, and different moisture contents of 2.5, 4.5, 6.5 and 8.5% (w.b). And duration of press was 11 min and applied pressure was 50 MPa. At the low temperature REO and VSPC of roasted and unroasted perilla seed increased in high moisture content and at the high temperature those increased in low moisture content. But REO and VSPC at 8.5% moisture content were decreased without relation to temperature. From the analysis of variance between expression factors and REO and VSPC, temperature and moisture contents showed high significance. Also the interaction effect between temperature and moisture content was higher than temperature. In our experimental conditions, the highest interaction effect between expression factors was observed in the range of $2.5{\sim}4.5%$ of moisture content in all temperatures. The maximum REO of unroasted perilla seeds was observed as 84.4% at 2.5% of moisture content and $60^{\circ}C$, and that of roasted one was as 84.3% at 6.5% of moisture content and $30^{\circ}C$.

• Journal of Adhesion and Interface
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• v.9 no.3
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• pp.20-26
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• 2008

It is well know that the structure of shape memory alloy (SMA) can change from martensite austenite by either temperature or stress. Due to their inherent shape recovery properties, SMA fiber can be used such as for stress or cure-monitoring sensor or actuator, during applied stress or temperature. Incomplete superelasticity was observed as the stress hysteresis at stress-strain curve under cyclic loading test and temperature change. Superelasticity behavior was observed for the single-SMA fiber/epoxy composites under cyclic mechanical loading at stress-strain curve. SMA fiber or epoxy embedded SMA fiber composite exhibited the decreased interfacial properties due to the cyclic loading and thus reduced shape memory performance. Rigid epoxy and the changed interfacial adhesion between SMA fiber and epoxy by the surface treatment on SMA fiber exhibited similar incomplete superelastic trend. Epoxy embedded single SMA fiber exhibited the incomplete recovery during cure process by remaining residual heat and thus occurring residual stress in single SMA fiber/epoxy composite.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.31 no.4
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• pp.183-190
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• 2018

This paper presents optimization of the main spar of Human-Powered Aircraft (HPA) wing. Mass minimization was attempted, while considering large torsional deformation of the beam. Sequential Quadratic Programming (SQP) method was adopted as a relevant tool to conduct structural optimization algorithm. An inner diameter and ply thicknesses of the main spar were selected as the design variables. The objective function includes factors such as mass minimization, constant tip bending displacement, and constant tip twist of the beam. For estimation of bending and torsional deformation, the geometrically exact beam model, which is appropriate for large deflection, was adopted. Properties of the cross sectional area which the geometrically exact beam model requires were obtained by Variational Asymptotic Beam Sectional Analysis (VABS), which is a cross sectional analysis program. As a result, maintaining tip bending displacement and tip twist within 1.45%, optimal design that accomplished 7.88% of the mass reduction was acquired. By the stress and strain recovery, structural integrity of the optimal design and validity of the present optimization procedure were authenticated.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.387-393
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• 1992

The fate of inoculum strain of Bradyrhizobium japonicum was studied by using genetically marked strain. RJB6 $str^rnal^rneo^r$. A spontaneous mutant of B. japonicum isolated from nodules was made to have antibiotic resistance against streptomycin and nalidixic acid. In order to make genetically marked strain, neomycine resistant gene(Tn5) was introduced into this spontaneous mutant by conjugation with E. coli containing pSUP2021. The southern hybridization was carried out to confirm the plasmid insertion. Hybridization of chromosome DNA using pSUP2021(Tn5) as a probe showed that Tn5 was located on the 4.9kb fragment of chromosome. Soybean seeds were planted into a soil previously cultivated with soybean and inoculated with different cell densities of marked strain. Fourty days after planting, the inoculation effects on nodule number, nodule fresh weight, plant height and nitrogen content in the plot inoculated with heavy cell suspension was a little better than those in the plot with low inoculation. The recovery percentage of the marked strains was about 12% in the plot inoculated with heavy density cell suspension, while 5% in the plot inoculated with low cell suspension.

• Journal of Cardiovascular Imaging
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• v.31 no.3
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• pp.125-132
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• 2023

BACKGROUND: There is limited data on the residual echocardiographic findings including strain analysis among post-coronavirus disease (COVID) patients. The aim of our study is to prospectively phenotype post-COVID patients. METHODS: All patients discharged following acute COVID infection were systematically followed in the post-COVID-19 Recovery Clinic at Vancouver General Hospital and St. Paul's Hospital. At 4-18 weeks post diagnosis, patients underwent comprehensive echocardiographic assessment. Left ventricular ejection fraction (LVEF) was assessed by 3D, 2D Biplane Simpson's, or visual estimate. LV global longitudinal strain (GLS) was measured using a vendor-independent 2D speckle-tracking software (TomTec). RESULTS: A total of 127 patients (53% female, mean age 58 years) were included in our analyses. At baseline, cardiac conditions were present in 58% of the patients (15% coronary artery disease, 4% heart failure, 44% hypertension, 10% atrial fibrillation) while the remainder were free of cardiac conditions. COVID-19 serious complications were present in 79% of the patients (76% pneumonia, 37% intensive care unit admission, 21% intubation, 1% myocarditis). Normal LVEF was seen in 96% of the cohort and 97% had normal right ventricular systolic function. A high proportion (53%) had abnormal LV GLS defined as < 18%. Average LV GLS of septal and inferior segments were lower compared to that of other segments. Among patients without pre-existing cardiac conditions, LVEF was abnormal in only 1.9%, but LV GLS was abnormal in 46% of the patients. CONCLUSIONS: Most post-COVID patients had normal LVEF at 4-18 weeks post diagnosis, but over half had abnormal LV GLS.