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1.
Materials (Basel) ; 17(8)2024 Apr 18.
Artículo en Inglés | MEDLINE | ID: mdl-38673233

RESUMEN

One of the most challenging elements of modeling the behaviour of reinforced concrete (RC) walls is combining realistic material models that can capture the observable behaviour of the physical system. Experiments with realistic loading rates and pressures reveal that steel and concrete display complicated nonlinear behaviour that is challenging to represent in a single constitutive model. To investigate the response of a reinforced concrete structure subjected to dynamic loads, this paper's study is based on many different material models to assess the advantages and disadvantages of the models on 2D and 3D RC walls using the LS-DYNA program. The models consisted of the KCC model and the CDP model, which represented plasticity and distinct tensile/compressive damage models, and the Winfrith model, which represented plasticity and the smeared crack model. Subsequently, the models' performances were assessed by comparing them to experimental data from reinforced concrete structures, in order to validate the accuracy of the overall behaviour prediction. The Winfrith model demonstrated satisfactory results in predicting the behaviour of 2D and 3D walls, including maximum strength, stiffness deterioration, and energy dissipation. The method accurately predicted the maximum strength of the Winfrith concrete model for the 2D wall with an error of 9.24% and for the 3D wall with errors of 3.28% in the X direction and 5.02% in the Y direction. The Winfrith model demonstrated higher precision in predicting dissipation energy for the 3D wall in both the X and Y directions, with errors of 6.84% and 6.62%, correspondingly. Additional parametric analyses were carried out to investigate structural behaviour, taking into account variables such as concrete strength, strain rate, mesh size, and the influence of the element type.

2.
Heliyon ; 10(2): e24704, 2024 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-38312692

RESUMEN

High-performance fibre-reinforced concrete (HPFRC), a type of cementitious composite material known for its exceptional mechanical performance, has widespread applications in structures exposed to severe dynamic loading conditions. However, understanding nonlinear HPFRC fracture behaviour, particularly under high strain rates, remains challenging given the complexities of assessment procedures and cost-intensive nature of experiments. This study presents an interpretable framework for modelling and analysing HPFRC fracture strength at high strain rates. A wide range of machine learning methods, including ensemble techniques, were employed to capture multivariate effects of eight essential input features (e.g., mortar compressive strength, fibre physical and mechanical properties, cross-sectional area, and strain rate) on fracture strength response. To assess the derived models, a novel evaluation procedure was proposed involving a data-based analysis, employing established metrics (i.e., coefficient of determination, root mean squared error, and mean absolute error via K-fold cross-validation) and a domain experts-involved evaluation utilising global sensitivity analysis to discern first-order and higher-order interactions among input factors. The proposed approach efficiently yielded both quantitative and qualitative insights into crucial input factors governing HPFRC fracture strength with limited experimental data. The obtained findings highlight the significance of multivariate effects, such as the interaction between strain rate and fibre tensile strength, and between fibre volume and fibre diameter, on fracture behaviour. The proposed interpretable framework aims to provide a powerful tool for proactive material failure analysis by understanding fracture behaviour and identifying potential weak and strong interactions among input factors of HPFRC-based samples. Moreover, the utilisation of the proposed approach enables researchers and civil engineers to efficiently focus on the most critical input parameters during the early design stage and ensuring the structural integrity and safety of HPFRC-based constructions.

3.
bioRxiv ; 2024 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-38260321

RESUMEN

Breast cancer progression and metastasis involve the action of multiple transcription factors in tumors and in the cells of the tumor microenvironment (TME) and understanding how these transcription factors are coordinated can guide novel therapeutic strategies. Myocardin related transcription factors A and B (MRTFA/B) are two related transcription factors that redundantly control cancer cell invasion and metastasis in mouse models of breast cancer, but their roles in human cancer are incompletely understood. Here, we used a combination of multiplexed immunofluorescence and bioinformatics analyses to show that MRTFA/B are concurrently activated in tumor cells, but they show distinct patterns of expression across different histological subtypes and in the TME. Importantly, MRTFA expression was elevated in metastatic tumors of African American patients, who disproportionately die from breast cancer. Interestingly, in contrast to publicly available mRNA expression data, MRTFA was similarly expressed across estrogen receptor (ER) positive and negative breast tumors, while MRTFB expression was highest in ER+ breast tumors. Furthermore, MRTFA was specifically expressed in the perivascular antigen presenting cells (APCs) and its expression correlated with the expression of the immune checkpoint protein V-set immunoregulatory receptor (VSIR). These results provide unique insights into how MRTFA and MRTFB can promote metastasis in human cancer, into the racial disparities of their expression patterns, and their function within the complex breast cancer TME.

4.
Sci Rep ; 13(1): 18070, 2023 Oct 23.
Artículo en Inglés | MEDLINE | ID: mdl-37872268

RESUMEN

Cast-in-place anchors are being increasingly used in many applications including building construction, bridge, and power plants. The anchorage to concrete systems are subjected to tensile, shear and combined loads from a variety of loading circumstances including static, dynamic, and shock loading. Despite extensive studies on these systems, reliable numerical models for predicting the behavior of these anchors are still limited. Therefore, this paper investigated the tensile behavior of cast-in-place anchorage to concrete systems, to propose an effective model for reproducing anchorage behavior using finite element (FE) methods. Experiments and code-based models for the anchorage system in tension were used to evaluate the numerical models for cast-in-place anchors in concrete, and the most suitable model, with advantages in accuracy and saving analysis time, was chosen. Finally, the FE model was used to study the tensile capacity and related dynamic increase factor for various strain rates, anchor diameters, and embedment depths.

5.
Nanomaterials (Basel) ; 13(7)2023 Apr 06.
Artículo en Inglés | MEDLINE | ID: mdl-37049382

RESUMEN

In this context, the open-circuit voltage generated by either poly (vinylidene fluoride) or PVDF and ZnO composite sample before being enhanced to 4.2 V compared to 1.2 V for the samples of pure PVDF. The spin coating method was used to create a composite film, which served as a piezoelectric nanogenerator (PNG). Zinc oxide (ZnO) nanoparticles and PVDF serve as the matrix for the coating structure. Thin films were created that employed the spin coating method to achieve the desired results of ZnO's non-brittle outcome and piezoelectric characteristics, as well as PVDF for use in self-powered devices. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and fourier transform infrared (FT-IR) were used to evaluate the properties of these formations. The electrical properties of the film were measured using an oscilloscope. Results indicated that by adding ZnO nanoparticles to the PVDF samples, piezoelectric capabilities were enhanced compared to samples containing PVDF only. These results point to promising uses for various wearable devices, such as water strider robot systems and self-operating equipment.

6.
Appl Microbiol Biotechnol ; 105(21-22): 8343-8358, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34648062

RESUMEN

Pancreatic cancer is a lethal cancer with aggressive and invasive characteristics. By the time it is diagnosed, patients already have tumors extended to other organs and show extremely low survival rates. The gut microbiome is known to be associated with many diseases and its imbalance affects the pathogenesis of pancreatic cancer. In this study, we established an orthotopic, patient-derived xenograft model to identify how the gut microbiome is linked to pancreatic ductal adenocarcinoma (PDAC). Using the 16S rDNA metagenomic sequencing, we revealed that the levels of Alistipes onderdonkii and Roseburia hominis decreased in the gut microbiome of the PDAC model. To explore the crosstalk between the two bacteria and PDAC cells, we collected the supernatant of the bacteria or cancer cell culture medium and treated it in a cross manner. While the cancer cell medium did not affect bacterial growth, we observed that the A. onderdonkii medium suppressed the growth of the pancreatic primary cancer cells. Using the bromodeoxyuridine/7-amino-actinomycin D (BrdU/7-AAD) staining assay, we confirmed that the A. onderdonkii medium inhibited the proliferation of the pancreatic primary cancer cells. Furthermore, RNA-seq analysis revealed that the A. onderdonkii medium induced unique transcriptomic alterations in the PDAC cells, compared to the normal pancreatic cells. Altogether, our data suggest that the reduction in the A. onderdonkii in the gut microbiome provides a proliferation advantage to the pancreatic cancer cells. KEY POINTS: • Metagenome analysis of pancreatic cancer model reveals A. onderdonkii downregulation. • A. onderdonkii culture supernatant suppressed the proliferation of pancreatic cancer cells. • RNA seq data reveals typical gene expression changes induced by A. onderdonkii.


Asunto(s)
Microbioma Gastrointestinal , Neoplasias Pancreáticas , Bacteroidetes , Línea Celular Tumoral , Proliferación Celular , Clostridiales , Regulación Neoplásica de la Expresión Génica , Humanos , Metagenoma , Neoplasias Pancreáticas/genética
7.
Front Psychol ; 12: 611464, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34248732

RESUMEN

This study aimed to verify the reliability and validity of the Korean version of the Work Need Satisfaction Scale for working adults, based on the psychology of working theory. A total of 589 working adults in Korea responded to the online survey. Of these respondents, 339 were used for exploratory factor analysis and 250 for confirmatory factor analysis. In Stage 1, we translated all items into Korean, back-translated them into English, and then verified the accuracy of the translation. Exploratory factor analysis revealed the 5-factor structure of the Korean version of the Work Need Satisfaction Scale reflecting those of the original scale (survival needs, social contribution needs, autonomy, relatedness, and competence). The scale showed good internal consistency. In Stage 2, confirmatory factor analysis was conducted, and the results indicated that there were no significant differences between a correlational model, a higher-order model, and a higher-order self-determination needs model. Thus, we offered a higher-order self-determination needs model, which had better model fit and was consistent with the original scale and the psychology of working theoretical framework. In addition, convergent and discriminant validity were supported by correlation estimates of the Korean version of the Work Need Satisfaction Scale, and the concurrent validity showed that the Korean version of the Work Need Satisfaction Scale had a significant proportion of explained variance for outcomes. The findings support the conclusion that this study established strong internal consistency and validity for the Korean version of the Work Need Satisfaction Scale. Thus, the scale is unique and meaningful for measuring need satisfaction in work settings in Korea.

8.
Int J Mol Sci ; 21(17)2020 Aug 27.
Artículo en Inglés | MEDLINE | ID: mdl-32867271

RESUMEN

ADAR (adenosine deaminase acting on RNA) catalyzes the deamination of adenosine to generate inosine, through its binding to double-stranded RNA (dsRNA), a phenomenon known as RNA editing. One of the functions of ADAR1 is suppressing the type I interferon (IFN) response, but its mechanism in gastric cancer is not clearly understood. We analyzed changes in RNA editing and IFN signaling in ADAR1-depleted gastric cancer cells, to clarify how ADAR1 regulates IFN signaling. Interestingly, we observed a dramatic increase in the protein level of signal transducer and activator of transcription 1 (STAT1) and interferon regulatory factor 9 (IRF9) upon ADAR1 knockdown, in the absence of type I or type II IFN treatment. However, there were no changes in protein expression or localization of the mitochondrial antiviral signaling protein (MAVS) and interferon alpha and beta-receptor subunit 2 (IFNAR2), the two known mediators of IFN production. Instead, we found that miR-302a-3p binds to the untranslated region (UTR) of IRF9 and regulate its expression. The treatment of ADAR1-depleted AGS cells with an miR-302a mimic successfully restored IRF9 as well as STAT1 protein level. Hence, our results suggest that ADAR1 regulates IFN signaling in gastric cancer through the suppression of STAT1 and IRF9 via miR-302a, which is independent from the RNA editing of known IFN production pathway.


Asunto(s)
Adenosina Desaminasa/genética , Subunidad gamma del Factor 3 de Genes Estimulados por el Interferón/metabolismo , Interferones/metabolismo , MicroARNs/genética , Proteínas de Unión al ARN/genética , Factor de Transcripción STAT2/metabolismo , Neoplasias Gástricas/genética , Regiones no Traducidas 3' , Proteínas Adaptadoras Transductoras de Señales/metabolismo , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Técnicas de Silenciamiento del Gen , Células HEK293 , Humanos , Subunidad gamma del Factor 3 de Genes Estimulados por el Interferón/genética , Edición de ARN , Receptor de Interferón alfa y beta/metabolismo , Transducción de Señal , Neoplasias Gástricas/metabolismo
9.
Front Psychol ; 10: 2360, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31681127

RESUMEN

This study investigated the possible mediation of career distress in the relationship between major incongruence and occupational engagement and whether this mediation depends on the degree of outcome expectation. Moderated mediation analysis was tested on a sample of 346 Korean undergraduate students. The results indicated that career distress mediated the relationship between major incongruence and occupational engagement. Moreover, the negative indirect effect of major incongruence on occupational engagement through career distress weakened as the level of outcome expectation increased. The significant mediation effect of career distress is meaningful given the evidence on the role of emotion in career adaptation. In addition, the significant moderation effect of cognitive evaluation and belief in the mediating relationship on career problem, career emotion, and career behavior is meaningful in that it provides insights in cognitive intervention that could be effective in career counseling.

10.
Front Psychol ; 10: 2093, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31620047

RESUMEN

This study examined the moderated mediation roles of job insecurity through career adaptability on the relation between core self-evaluation (CSE) and work engagement. A total of 335 Korean full-time employees who had been employed for <3 years responded to the questionnaire survey. Excluding missing data and outliers, data from 324 participants (men = 82, women = 242) were analyzed using SPSS 25.0 and SPSS PROCESS Macro. The results indicated that job insecurity moderated the indirect association between CSE and work engagement via career adaptability. This study further expanded the understanding of newly employed employees' adaptation. Implications and limitations of the study and suggestions for further study were discussed.

11.
J Couns Psychol ; 66(6): 701-713, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31259574

RESUMEN

Psychology of Working Theory (PWT; Duffy, Blustein, Diemer, & Autin, 2016) is a recently developed framework aimed at documenting predictors and outcomes of decent work. To date, no studies have explored the applicability of the psychology of working perspective with emerging adults. The goal of the present study is to examine the predictor portion of PWT with a sample of Korean emerging adults from diverse economic backgrounds. Data were collected from a sample of 407 emerging adults attending a large junior college in Korea. Overall, most of the hypothesized direct paths were significant, with economic resources positively relating to both work volition and career adaptability and these positively relating to occupational engagement and future perceptions of securing decent work. Support for the hypothesized indirect effects was mixed. Overall, results suggest that the PWT is generally relevant and applicable to emerging adults when population-appropriate outcomes are included in the model and that the theory is supported in the Korean context. Based on the results, we also propose that interventions based on malleable psychological factors-the mediators in our study-may be targets when working with emerging adults experiencing economic constraints. (PsycINFO Database Record (c) 2019 APA, all rights reserved).


Asunto(s)
Selección de Profesión , Motivación/fisiología , Ocupaciones/tendencias , Estudiantes/psicología , Universidades/tendencias , Volición/fisiología , Adulto , Estudios Transversales , Femenino , Humanos , Masculino , República de Corea/epidemiología
12.
J Nucl Med ; 56(11): 1793-9, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26315828

RESUMEN

UNLABELLED: Intraarterial microdosing (IAM) is a novel drug development approach combining intraarterial drug delivery and microdosing. We aimed to demonstrate that IAM leads to target exposure similar to that of systemic full-dose administration but with minimal systemic exposure. IAM could enable the safe, inexpensive, and early study of novel drugs at the first-in-human stage and the study of established drugs in vulnerable populations. METHODS: Insulin was administered intraarterially (ipsilateral femoral artery) or systemically to 8 CD IGS rats just before blood sampling or 60-min (18)F-FDG uptake PET imaging of ipsilateral and contralateral leg muscles (lateral gastrocnemius) and systemic muscles (spinotrapezius). The (18)F-FDG uptake slope analysis was used to compare the interventions. Plasma levels of insulin and glucose were compared using area under the curve calculated by the linear trapezoidal method. A physiologically based computational pharmacokinetics/pharmacodynamics model was constructed to simulate the relationship between the administered dose and response over time. RESULTS: (18)F-FDG slope analysis found no difference between IAM and systemic full-dose slopes (0.0066 and 0.0061, respectively; 95% confidence interval [CI], -0.024 to 0.029; P = 0.7895), but IAM slope was statistically significantly greater than systemic microdose (0.0018; 95% CI, -0.045 to -0.007; P = 0.0147) and sham intervention (-0.0015; 95% CI, 0.023-0.058; P = 0.0052). The pharmacokinetics/pharmacodynamics data were used to identify model parameters that describe membrane insulin binding and glucose-insulin dynamics. CONCLUSION: Target exposure after IAM was similar to systemic full dose administration but with minimal systemic effects. The computational pharmacokinetics/pharmacodynamics model can be generalized to predict whole-body response. Findings should be validated in larger, controlled studies in animals and humans using a range of targets and classes of drugs.


Asunto(s)
Fluorodesoxiglucosa F18/administración & dosificación , Tomografía de Emisión de Positrones/métodos , Radiofármacos/administración & dosificación , Algoritmos , Animales , Glucemia/metabolismo , Simulación por Computador , Sistemas de Liberación de Medicamentos , Fluorodesoxiglucosa F18/efectos adversos , Fluorodesoxiglucosa F18/farmacocinética , Hipoglucemiantes/farmacología , Interpretación de Imagen Asistida por Computador , Inyecciones Intraarteriales , Insulina/sangre , Insulina/farmacología , Masculino , Modelos Estadísticos , Radiofármacos/efectos adversos , Radiofármacos/farmacocinética , Ratas
13.
J Thorac Cardiovasc Surg ; 142(2): 411-7, 2011 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21641005

RESUMEN

OBJECTIVES: Cerebral ischemia can occur during cardiopulmonary bypass, especially during low flow. HBOC-201 (OPK Biotech, Cambridge, Mass) is a hemoglobin-based oxygen-carrying solution that enhances oxygen delivery. This project evaluated the benefits on total body and cerebral oxygen delivery and consumption using HBOC-201 during cardiopulmonary bypass. METHODS: Twelve immature swine were assigned to one of 2 groups. One group used HBOC-201 in pump prime, and the other used donor porcine blood. Cardiopulmonary bypass was initiated and then flow was serially decreased from 100% to 75%, to 50%, and then back to full flow. At each interval, (15)O positron emission tomographic analysis was performed, and blood was collected. Total body and cerebral oxygen delivery and consumption were calculated. Statistical analysis was performed with a Tukey-Kramer adjusted P value based on a repeated measures linear model on log-transformed data. RESULTS: Total and plasma hemoglobin levels were higher in the HBOC-201 group. Oxygen delivery and consumption were not statistically different but did tend to be higher in the HBOC-201 group. Mixed venous saturation was lower in the HBOC-201 group but not significant. Mild metabolic acidosis with increased lactate levels developed in the blood group. Mean cerebral blood flow decreased in both groups when total flow was 50%. In the HBOC-201 group cerebral oxygen metabolism was maintained. CONCLUSIONS: The addition of HBOC-201 for cardiopulmonary bypass appears to improve oxygen use and minimize anaerobic metabolism. Cerebral oxygen use was preserved in the HBOC-201 group, even during decrease in blood flow. These findings support the reported improved oxygen-unloading properties of HBOC-201 and might provide a benefit during cardiopulmonary bypass.


Asunto(s)
Acidosis Láctica/prevención & control , Sustitutos Sanguíneos/uso terapéutico , Encéfalo/metabolismo , Puente Cardiopulmonar , Hemoglobinas/uso terapéutico , Oxígeno/metabolismo , Animales , Circulación Cerebrovascular , Hemoglobinas/análisis , Consumo de Oxígeno , Porcinos
14.
Magn Reson Med ; 65(3): 744-9, 2011 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21337407

RESUMEN

Cerebral blood volume (CBV) has been shown to be an important biomarker in a number of neurological disorders and in the quantitative interpretation of functional MRI. One approach to determine CBV in humans is vascular-space-occupancy MRI, and this technique has been applied to the studies of brain glioma, Schizophrenia, and Alzheimer's disease. However, validation of this technique with a gold standard method has not been reported. In this study, we compared vascular-space-occupancy MRI with a radiotracer-based positron emission tomography technique in a group of healthy subjects. It was found that regional CBV measured with vascular-space-occupancy MRI was highly correlated with that of the positron emission tomography data (R=0.79±0.10, N=8). Furthermore, absolute CBV values quantified by vascular-space-occupancy were also in excellent agreement with those by positron emission tomography (slope=1.00±0.15). Because of the differences in the labeling principles between the two modalities, systematic CBV differences were observed in large vessel and ventricle regions.


Asunto(s)
Determinación del Volumen Sanguíneo/métodos , Volumen Sanguíneo/fisiología , Encéfalo/fisiología , Circulación Cerebrovascular/fisiología , Imagen por Resonancia Magnética/métodos , Tomografía de Emisión de Positrones/métodos , Adulto , Encéfalo/anatomía & histología , Encéfalo/efectos de la radiación , Femenino , Humanos , Masculino , Reproducibilidad de los Resultados , Sensibilidad y Especificidad
15.
Rev Sci Instrum ; 79(6): 064301, 2008 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18601420

RESUMEN

We developed an intra-arterial positron-probe (beta(+)-probe) system to measure the arterial time-activity concentration in humans for quantitative compartmental modeling of positron emission tomography studies. Performance was characterized in vitro, by using a uniform phantom to calculate dead time, linearity, and absolute detector sensitivity. In vitro evaluations in a uniform phantom showed a system dead time of 2.5 micros, linear regression between measured and true count rates with R(2)=0.999, and detector sensitivity of 6.9-7.0 counts/s kBq(-1) ml. These met or exceeded values of previously reported systems.


Asunto(s)
Angiografía/instrumentación , Tomografía de Emisión de Positrones/instrumentación , Trazadores Radiactivos , Angiografía/métodos , Arterias , Humanos , Tomografía de Emisión de Positrones/métodos
16.
Nucl Med Commun ; 27(7): 573-81, 2006 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16794518

RESUMEN

OBJECTIVE: The quantitative measurement of cerebral metabolic rate of oxygen (CMRO(2)) for rats using positron emission tomography (PET) has been technically difficult. The present study was performed to provide a technique to measure CMRO(2) for rats using a dedicated animal PET technique. METHODS: CMRO(2) in the rat brain was quantitatively measured under alpha-chloralose anaesthesia (30 mg . kg(-1) . h(-1), intravenous infusion) using a PET imaging technique. In our experiment, the (15)O-labelled gas tracer (O(15)O) was administered by a bolus insufflation into the lung through a surgically placed cannula in the trachea. The tracer distribution was then dynamically imaged using the microPET. Unlike other conventional PET methods in which a series of arterial blood samples need to be withdrawn for the measurement of an arterial input function, no arterial blood sampling was employed. Instead, the heart was scanned in dynamic mode at the same time of imaging the brain, and the region of interest drawn over the heart was analysed to obtain an arterial input function. RESULTS: The CMRO(2) value (micromol . 100 g(-1) . min(-1)) from 10 rats was 208 +/- 15 (mean +/- SD). CONCLUSIONS: Our results suggest that the microPET-based CMRO(2) measurement in the rat brain combined with a non-invasive measurement of arterial input function is promising, especially for many applications involving small animals in which repeated measurements of absolute CMRO(2) need to be performed.


Asunto(s)
Mapeo Encefálico/métodos , Encéfalo/diagnóstico por imagen , Encéfalo/fisiología , Interpretación de Imagen Asistida por Computador/métodos , Radioisótopos de Oxígeno , Oxígeno/metabolismo , Tomografía de Emisión de Positrones/métodos , Administración por Inhalación , Animales , Gases/administración & dosificación , Masculino , Tasa de Depuración Metabólica , Consumo de Oxígeno/fisiología , Radioisótopos de Oxígeno/administración & dosificación , Tomografía de Emisión de Positrones/veterinaria , Radiofármacos , Ratas , Ratas Endogámicas F344
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