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1.
Artigo em Inglês | MEDLINE | ID: mdl-33017935

RESUMO

Temporal enhanced ultrasound (TeUS) is a tissue characterization approach based on analysis of a temporal series of US data. Previously we demonstrated that intrinsic or external micro-motions of scatterers in the tissue contribute towards the tissue classification properties of TeUS. This property is beneficial to detect early stage cancer, for example, where changes in nuclei configuration (scatteres) dominate tissue properties. In this study, we propose an analytical derivation and experiments to acquire TeUS through manipulation of US imaging parameters, which may be simpler to translate to clinical applications. The feasibility of the proposed method is demonstrated on tissue-mimicking phantoms. Using an autoencoder classifier, we are able to classify phantoms of varying elasticities and scattering sizes.


Assuntos
Ultrassonografia , Elasticidade , Estudos de Viabilidade , Imagens de Fantasmas
2.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 4680-4686, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33019038

RESUMO

Passive elastic elements can contribute to stability, energetic efficiency, and impact absorption in both biological and robotic systems. They also add dynamical complexity which makes them more challenging to model and control. The impact of this added complexity to autonomous learning has not been thoroughly explored. This is especially relevant to tendon-driven limbs whose cables and tendons are inevitably elastic. Here, we explored the efficacy of autonomous learning and control on a simulated bio-plausible tendon-driven leg across different tendon stiffness values. We demonstrate that increasing stiffness of the simulated muscles can require more iterations for the inverse map to converge but can then perform more accurately, especially in discrete tasks. Moreover, the system is robust to subsequent changes in muscle stiffnesses and can adapt on-the-go within 5 attempts. Lastly, we test the system for the functional task of locomotion and found similar effects of muscle stiffness to learning and performance. Given that a range of stiffness values led to improved learning and maximized performance, we conclude the robot bodies and autonomous controllers-at least for tendon-driven systems-can be co-developed to take advantage of elastic elements. Importantly, this opens also the door to development efforts that recapitulate the beneficial aspects of the co-evolution of brains and bodies in vertebrates.


Assuntos
Procedimentos Cirúrgicos Robóticos , Robótica , Animais , Elasticidade , Músculo Esquelético , Tendões
3.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 1807-1810, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018350

RESUMO

In this paper, for the first time, a triple-mode scan using electromagnetic waves, in the shape of millimeter waves, and ultrasound waves, to obtain B-mode and quasistatic elastography images of a phantom of human breast tissues is shown. A homogeneous phantom composed of nontoxic, low-cost and easy-to-handle materials (i.e. water, oil, gelatin and dishwashing liquid) was produced, with an inclusion made of water and agar. These are intended to mimic, in terms of dielectric properties, healthy adipose tissues and neoplastic tissues, respectively. A millimeter-wave imaging prototype was used to scan the phantom, by implementing a linear synthetic array of 24 antennas with a central working frequency of 30 GHz. The phantom was then scanned using an ultrasound research system and a linear-array probe at 7 MHz, acquiring both B-mode and quasi-static elastography images. The millimeter-wave system showed an excellent ability to detect the target placed at about 1.4 cm depth. Also in the ultrasound case the inclusion was correctly detected as a hypoechoic, stiff mass. This first experimental findings show that millimeter-wave, ultrasound and elasticity imaging can be used jointly to detect tumor-like targets into phantoms mimicking healthy breast tissues. Thus, they provide promising preliminary results to further study the application of this multimodal approach in all those critical cases in which such complementary imaging techniques could be exploited for an enhanced tumor detection, based on tissues dielectric, acoustic and elastic properties.


Assuntos
Neoplasias da Mama , Técnicas de Imagem por Elasticidade , Neoplasias da Mama/diagnóstico por imagem , Elasticidade , Humanos , Imagens de Fantasmas , Ultrassonografia
4.
Annu Int Conf IEEE Eng Med Biol Soc ; 2020: 2079-2083, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-33018415

RESUMO

The placenta is a vital organ for growth and development of the fetus. Shear Wave Absolute Vibro-Elastography (SWAVE) is a new elastography technique proposed to detect placenta disorders. Elastography involves applying a force on the tissue and measuring the resulting tissue deformation. All types of compression cause the tissue to expand in three directions given the biological tissues are nearly incompressible. Hence, 3D displacement estimation should lead to the most accurate elasticity reconstruction compared to the traditional 1D methods. Previous studies estimated 3D displacements over ultrasound volumes mostly for quasi-static compression to generate strain images. However, accurate displacement tracking of dynamic motion continues to be a challenge. In this work, a novel volumetric regularized algorithm, 3D GLobal Ultrasound Elastography (GLUE3D), is presented to estimate the 3D displacement over a volume of ultrasound data, following by a 3D Young's modulus reconstruction. The proposed method outperforms the previous 2D method over a volume and is compared with a 3D technique using phantom data for which the elasticity are provided by the values from magnetic resonance elastography on the same phantom and also the manufacturer reference numbers. We then present Young's modulus reconstruction results obtained from clinical data of placenta which shows more uniform elasticity maps compared to the traditional 1D displacement measurements over a volume of ultrasound data. Furthermore, the dependency of the elasticity values to the frequency is investigated in this study.


Assuntos
Técnicas de Imagem por Elasticidade , Módulo de Elasticidade , Elasticidade , Feminino , Humanos , Imagens de Fantasmas , Placenta/diagnóstico por imagem , Gravidez
5.
Medicine (Baltimore) ; 99(37): e22120, 2020 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-32925760

RESUMO

The purpose of this study is to study sonoelastographic features of the saphenous nerve.The study included 72 saphenous nerves in 36 healthy subjects. High resolution ultrasound and Shearwave elastography were used to evaluate the saphenous nerve. Cross sectional area (CSA) and stiffness were measured.The mean CSA of the saphenous nerve was 5.7 mm. The mean shear elastic modulus of the saphenous nerve in the short axis was 29.5 kPa. The mean shear elastic modulus of the saphenous nerve in long axis was 29.9 kPa. The saphenous nerve elastic modulus also showed no correlation with CSA in neither the long axis nor short axis. Positive correlation between elasticity measurements in the long and short axes. Age, height, weight, and BMI showed no correlation with saphenous nerve elastic modulus in short or long axes.The elastic modulus of the saphenous nerve has been determined in healthy subjects and can serve as a reference for future assessment of the saphenous nerve before different procedures.


Assuntos
Técnicas de Imagem por Elasticidade , Elasticidade/fisiologia , Nervos Periféricos/diagnóstico por imagem , Nervos Periféricos/fisiologia , Coxa da Perna/inervação , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valores de Referência , Coxa da Perna/diagnóstico por imagem , Adulto Jovem
6.
Medicine (Baltimore) ; 99(37): e22144, 2020 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-32925769

RESUMO

The aim of this study was to determine the effectiveness of a skin stretching technique with adjustable external fixators in treating skin defects.Eighteen patients treated with a skin-stretching technique with adjustable external fixators for skin defects from April 2017 to October 2019 were included. Visual Analogue Scale (VAS) scores were collected during therapy. The skin defects gradually became smaller until they were completely resolved according to the blood flow of the affected limb and wound skin (the color, temperature, elasticity, and capillary response). The defect sizes ranged from 4 cm × 2 cm to 20 cm × 6 cm.The 18 adjustable external fixators were dismantled in 2 to 9 days (mean, 4.05 days) after the operation, and the defects were completely closed and the sutures were removed after 2 to 3 weeks. The average VAS score was 5.97. The follow-up period was 4 to 12 months (mean, 6.3 months); 17 patients healed well with linear small scar, and no infections or patients of necrosis were observed. Sensory recovery was assessed using the Medical Research Council scale, and all the sensation scores were S3+. Eight patients were healed after the first stage. Nine patients were closed totally while small sinus or skin defect were observed after sutures were removed; 3 patients were healed after the second debridement, and 6 patients finally healed after the dressings were changed. Patellar osteomyelitis recurred in 1 patient who was transferred to the Orthopedic Department for further treatment, and a flap graft procedure was performed.The operation was simple and obviously reduced the course of the disease, the costs, and the damage to the donor site, and it is also significantly superior to skin graft or flap transplantation procedures in terms of the resulting skin sensation, color, texture, elasticity, and appearance.


Assuntos
Fixadores Externos , Procedimentos Cirúrgicos Reconstrutivos/métodos , Cicatrização/fisiologia , Ferimentos e Lesões/terapia , Adulto , Idoso , Elasticidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Medição da Dor , Satisfação do Paciente , Pigmentação da Pele , Temperatura Cutânea , Fatores de Tempo
7.
Nat Commun ; 11(1): 4616, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32934229

RESUMO

Para-nematic phases, induced by unwinding chiral helices, spontaneously relax to a chiral ground state through phase ordering dynamics that are of great interest and crucial for applications such as stimuli-responsive and biomimetic engineering. In this work, we characterize the cholesteric phase relaxation behaviors of ß-lactoglobulin amyloid fibrils and cellulose nanocrystals confined into cylindrical capillaries, uncovering two different equilibration pathways. The integration of experimental measurements and theoretical predictions reveals the starkly distinct underlying mechanism behind the relaxation dynamics of ß-lactoglobulin amyloid fibrils, characterized by slow equilibration achieved through consecutive sigmoidal-like steps, and of cellulose nanocrystals, characterized by fast equilibration obtained through smooth relaxation dynamics. Particularly, the specific relaxation behaviors are shown to emerge from the order parameter of the unwound cholesteric medium, which depends on chirality and elasticity. The experimental findings are supported by direct numerical simulations, allowing to establish hard-to-measure viscoelastic properties without applying magnetic or electric fields.


Assuntos
Lactoglobulinas/química , Cristais Líquidos/química , Amiloide/química , Coloides/química , Elasticidade , Cinética , Nanopartículas/química , Transição de Fase , Temperatura
8.
PLoS One ; 15(9): e0234224, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32970682

RESUMO

Gillnets made of the biodegradable resin polybutylene succinate co-adipate-co-terephthalate were tested under commercial fishing conditions to compare their fishing performance with that of conventional nylon polyamide (PA) gillnets. Both types of gillnets were made of 0.55 mm Ø monofilaments. However, since the biodegradable nets are weaker than nylon PA nets when using the same monofilament diameter, we also used biodegradable nets made of 0.60 mm Ø monofilament that had a similar tensile strength to the 0.55 mm Ø nylon PA nets. The relative catch efficiency of the different gillnet types was evaluated over the 2018 autumn fishing season for saithe and cod in northern Norway. For cod, both biodegradable gillnets (0.55 and 0.60 mm) had a significantly lower catch efficiency compared to the traditional nylon PA net (0.55 mm) with estimated catch efficiencies of 62.38% (CI: 50.55-74.04) and 54.96% (CI: 35.42-73.52) compared with the nylon PA net, respectively. Similarly for saithe, both biodegradable gillnets (0.55 and 0.60 mm) had a lower estimated catch efficiency compared to the traditional nylon PA net (0.55 mm) with estimated catch efficiencies of 83.40% (71.34-94.86) and 83.87% (66.36-104.92), compared with the nylon PA net, respectively. Tensile strength does not explain the differences in catch efficiency between the two gillnet types, since increasing the twine diameter of the biodegradable gillnets (to match the strength of nylon PA gillnets) did not yield similar catch efficiencies. However, the elasticity and stiffness of the materials may be responsible for the differences in catch efficiency between the nylon PA and biodegradable gillnets.


Assuntos
Pesqueiros , Nylons/química , Poliésteres/química , Animais , Biodegradação Ambiental , Elasticidade , Poluentes Ambientais/química , Peixes , Noruega , Resistência à Tração
9.
Nat Commun ; 11(1): 4757, 2020 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-32958771

RESUMO

Local tissue mechanics play a critical role in cell function, but measuring these properties at cellular length scales in living 3D tissues can present considerable challenges. Here we present thermoresponsive, smart material microgels that can be dispersed or injected into tissues and optically assayed to measure residual tissue elasticity after creep over several weeks. We first develop and characterize the sensors, and demonstrate that internal mechanical profiles of live multicellular spheroids can be mapped at high resolutions to reveal broad ranges of rigidity within the tissues, which vary with subtle differences in spheroid aggregation method. We then show that small sites of unexpectedly high rigidity develop in invasive breast cancer spheroids, and in an in vivo mouse model of breast cancer progression. These focal sites of increased intratumoral rigidity suggest new possibilities for how early mechanical cues that drive cancer cells towards invasion might arise within the evolving tumor microenvironment.


Assuntos
Fenômenos Biomecânicos , Técnicas Biossensoriais/métodos , Hidrogéis/química , Animais , Técnicas Biossensoriais/instrumentação , Linhagem Celular , Elasticidade , Humanos , Camundongos , Modelos Biológicos , Neoplasias Experimentais/patologia , Esferoides Celulares/patologia , Esferoides Celulares/fisiologia , Temperatura
10.
PLoS One ; 15(8): e0236406, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32745098

RESUMO

To address concerns over plastics in the global environment, this project produced three wood plastics composites (WPCs) which could divert plastics from the waste stream into new materials. The three materials made had a ratio of 85%:15%, 90%:10%, and 95%:5% low density polyethylene (LDPE) to wood powder and were produced using the dissolution method. Physical and mechanical properties of each WPC were evaluated according to Japanese Industrial Standard (JIS) A 5908:2003. Their degradation in nature was evaluated through a graveyard test and assay test conducted in Coptotermes curvignathus termites. Results showed that density, moisture content, thickness swelling and water absorption of the WPCs fulfilled the JIS standard. The mechanical properties of these composites also met the JIS standard, particularly their modulus of elasticity (MOE). Modulus of rupture (MOR) and internal bonding (IB) showed in lower values, depending on the proportion of wood filler they contained. Discoloration of the WPCs was observed after burial in the soil with spectra alteration of attenuated transmission reflectance (ATR) in the band of 500-1000 cm-1 which could be assigned to detach the interphase between wood and plastics. As termite bait, the WPCs decreased in weight, even though the mass loss was comparatively small. Micro Confocal Raman Imaging Spectrometer revealed that termite guts from insects feeding on WPCs contained small amounts of LDPE. This indicated termite can consume plastics in the form of WPCs. Thus WPCs made predominantly of plastics can be degraded in nature. While producing WPCs can assist in decreasing plastics litter in the environment, the eventual fate of the LDPE in termites is still unknown.


Assuntos
Plásticos Biodegradáveis/química , Elasticidade , Polietileno/química , Madeira/química , Plásticos Biodegradáveis/síntese química , Humanos , Polietileno/síntese química , Reciclagem , Água/química
11.
Phys Rev Lett ; 125(6): 068101, 2020 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-32845697

RESUMO

Shape, dynamics, and viscoelastic properties of eukaryotic cells are primarily governed by a thin, reversibly cross-linked actomyosin cortex located directly beneath the plasma membrane. We obtain time-dependent rheological responses of fibroblasts and MDCK II cells from deformation-relaxation curves using an atomic force microscope to access the dependence of cortex fluidity on prestress. We introduce a viscoelastic model that treats the cell as a composite shell and assumes that relaxation of the cortex follows a power law giving access to cortical prestress, area-compressibility modulus, and the power law exponent (fluidity). Cortex fluidity is modulated by interfering with myosin activity. We find that the power law exponent of the cell cortex decreases with increasing intrinsic prestress and area-compressibility modulus, in accordance with previous finding for isolated actin networks subject to external stress. Extrapolation to zero tension returns the theoretically predicted power law exponent for transiently cross-linked polymer networks. In contrast to the widely used Hertzian mechanics, our model provides viscoelastic parameters independent of indenter geometry and compression velocity.


Assuntos
Actinas/química , Fibroblastos/química , Fibroblastos/citologia , Modelos Biológicos , Actinas/fisiologia , Animais , Fenômenos Biomecânicos , Linhagem Celular , Membrana Celular/química , Membrana Celular/fisiologia , Força Compressiva , Cães , Elasticidade , Microscopia de Força Atômica , Miosinas/química , Miosinas/fisiologia , Reologia/métodos , Viscosidade
12.
Phys Rev Lett ; 125(7): 078003, 2020 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-32857587

RESUMO

Determining the positions of lattice defects on bounded elastic surfaces with Gaussian curvature is a nontrivial task of mechanical energy optimization. We introduce a simple way to predict the onset of disclination disorder from the shape of the surface. The criterion fixes the value of a weighted integral Gaussian curvature to a universal constant and proves accurate across a great variety of shapes. It provides improved understanding of the limitations to crystalline order in many natural and engineering contexts, such as the assembly of viral capsids.


Assuntos
Capsídeo/química , Modelos Teóricos , RNA/química , Animais , Proteínas do Capsídeo/química , Drosophila , Elasticidade , HIV/química , Vírus da SARS/química , Propriedades de Superfície , Termodinâmica , Thermoproteus
13.
PLoS One ; 15(8): e0237747, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32822369

RESUMO

With the great significance of biomolecular flexibility in biomolecular dynamics and functional analysis, various experimental and theoretical models are developed. Experimentally, Debye-Waller factor, also known as B-factor, measures atomic mean-square displacement and is usually considered as an important measurement for flexibility. Theoretically, elastic network models, Gaussian network model, flexibility-rigidity model, and other computational models have been proposed for flexibility analysis by shedding light on the biomolecular inner topological structures. Recently, a topology-based machine learning model has been proposed. By using the features from persistent homology, this model achieves a remarkable high Pearson correlation coefficient (PCC) in protein B-factor prediction. Motivated by its success, we propose weighted-persistent-homology (WPH)-based machine learning (WPHML) models for RNA flexibility analysis. Our WPH is a newly-proposed model, which incorporate physical, chemical and biological information into topological measurements using a weight function. In particular, we use local persistent homology (LPH) to focus on the topological information of local regions. Our WPHML model is validated on a well-established RNA dataset, and numerical experiments show that our model can achieve a PCC of up to 0.5822. The comparison with the previous sequence-information-based learning models shows that a consistent improvement in performance by at least 10% is achieved in our current model.


Assuntos
RNA/química , Algoritmos , Elasticidade , Aprendizado de Máquina , Distribuição Normal , Conformação de Ácido Nucleico
14.
Nature ; 584(7822): 535-546, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32848221

RESUMO

Substantial research over the past two decades has established that extracellular matrix (ECM) elasticity, or stiffness, affects fundamental cellular processes, including spreading, growth, proliferation, migration, differentiation and organoid formation. Linearly elastic polyacrylamide hydrogels and polydimethylsiloxane (PDMS) elastomers coated with ECM proteins are widely used to assess the role of stiffness, and results from such experiments are often assumed to reproduce the effect of the mechanical environment experienced by cells in vivo. However, tissues and ECMs are not linearly elastic materials-they exhibit far more complex mechanical behaviours, including viscoelasticity (a time-dependent response to loading or deformation), as well as mechanical plasticity and nonlinear elasticity. Here we review the complex mechanical behaviours of tissues and ECMs, discuss the effect of ECM viscoelasticity on cells, and describe the potential use of viscoelastic biomaterials in regenerative medicine. Recent work has revealed that matrix viscoelasticity regulates these same fundamental cell processes, and can promote behaviours that are not observed with elastic hydrogels in both two- and three-dimensional culture microenvironments. These findings have provided insights into cell-matrix interactions and how these interactions differentially modulate mechano-sensitive molecular pathways in cells. Moreover, these results suggest design guidelines for the next generation of biomaterials, with the goal of matching tissue and ECM mechanics for in vitro tissue models and applications in regenerative medicine.


Assuntos
Elasticidade , Matriz Extracelular/metabolismo , Substâncias Viscoelásticas , Materiais Biocompatíveis/química , Materiais Biocompatíveis/metabolismo , Técnicas de Cultura de Células , Forma Celular , Matriz Extracelular/química , Humanos , Mecanotransdução Celular , Células-Tronco Mesenquimais/citologia , Modelos Biológicos , Medicina Regenerativa
15.
Sr Care Pharm ; 35(9): 379-387, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32807261

RESUMO

Skin tears are a common occurrence in older people, though many are unfamiliar with them until late in life. These painful wounds are more likely to occur with age as the skin experiences age-related changes. Numerous factors including declining dermal thickness and loss of elasticity contribute to their development. Risk increases in patients who need assistance with activities of daily living or who need help transferring from bed or chair. Polypharmacy is a risk factor. Prevention is the best approach, but once skin tears develop, treatment needs to be tailored to the tear's grade.


Assuntos
Lesões dos Tecidos Moles , Atividades Cotidianas , Idoso , Idoso de 80 Anos ou mais , Elasticidade , Humanos , Lacerações , Pele
16.
Phys Rev Lett ; 125(5): 058102, 2020 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-32794888

RESUMO

Animal hearts are soft shells that actively pump blood to oxygenate tissues. Here, we propose an allometric scaling law for the heart rate based on the idea of elastohydrodynamic resonance of a fluid-loaded soft active elastic shell that buckles and contracts axially when twisted periodically. We show that this picture is consistent with numerical simulations of soft cylindrical shells that twist-buckle while pumping a viscous fluid, yielding optimum ejection fractions of 35%-40% when driven resonantly. Our scaling law is consistent with experimental measurements of heart rates over 2 orders of magnitude, and provides a mechanistic basis for how metabolism scales with organism size. In addition to providing a physical rationale for the heart rate and metabolism of an organism, our results suggest a simple design principle for soft fluidic pumps.


Assuntos
Frequência Cardíaca/fisiologia , Coração/anatomia & histologia , Coração/fisiologia , Modelos Cardiovasculares , Animais , Simulação por Computador , Elasticidade , Ventrículos do Coração/anatomia & histologia , Hidrodinâmica , Função Ventricular
17.
Proc Natl Acad Sci U S A ; 117(28): 16154-16159, 2020 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-32601228

RESUMO

The metaphase spindle is a dynamic structure orchestrating chromosome segregation during cell division. Recently, soft matter approaches have shown that the spindle behaves as an active liquid crystal. Still, it remains unclear how active force generation contributes to its characteristic spindle-like shape. Here we combine theory and experiments to show that molecular motor-driven forces shape the structure through a barreling-type instability. We test our physical model by titrating dynein activity in Xenopus egg extract spindles and quantifying the shape and microtubule orientation. We conclude that spindles are shaped by the interplay between surface tension, nematic elasticity, and motor-driven active forces. Our study reveals how motor proteins can mold liquid crystalline droplets and has implications for the design of active soft materials.


Assuntos
Metáfase/fisiologia , Fuso Acromático/fisiologia , Animais , Fenômenos Biomecânicos , Dineínas/antagonistas & inibidores , Dineínas/metabolismo , Elasticidade , Cristais Líquidos , Metáfase/efeitos dos fármacos , Microtúbulos/efeitos dos fármacos , Microtúbulos/fisiologia , Mitose , Fuso Acromático/química , Fuso Acromático/efeitos dos fármacos , Tensão Superficial , Proteínas de Xenopus/antagonistas & inibidores , Proteínas de Xenopus/metabolismo , Xenopus laevis
18.
Croat Med J ; 61(3): 223-229, 2020 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-32643338

RESUMO

AIM: To determine the relationship between breast stiffness assessed with sonoelastography (elasticity) and breast tissue density assessed with mammography (MG) and ultrasound (US). METHODS: This cross-sectional study involved 100 women who underwent MG, gray-scale US, and shear-wave sonoelastography during 2013. Mammographic density was categorized into four groups and sonographic density into three groups according to Breast Imaging-Reporting and Data System criteria. The stiffness of breast parenchymal and adipose tissue in all breast quadrants was quantified by shear-wave sonoelastography. Mean elastographic estimates were compared with MG- and US-derived density estimates. RESULTS: Parenchymal and adipose tissue elasticity positively correlated with MG- and US-derived breast density (for parenchyma: for MG Kendall's tau b 0.522; Jonckheere-Terpstra test P<0.001 and for US Kendall's tau b 0.533; Jonckheere-Terpstra test P<0.001); the higher was the breast density on MG and US, the higher was the elastographic stiffness. CONCLUSION: Sonoelastographic breast stiffness strongly positively correlated with breast density. Thus, sonoelastography may have a potential for estimating the breast cancer risk, which allows a novel application of this technique in routine clinical practice.


Assuntos
Tecido Adiposo/fisiologia , Densidade da Mama/fisiologia , Mama/diagnóstico por imagem , Mama/fisiologia , Técnicas de Imagem por Elasticidade/métodos , Tecido Parenquimatoso/fisiologia , Ultrassonografia Mamária/métodos , Adulto , Idoso , Estudos Transversais , Elasticidade/fisiologia , Feminino , Humanos , Pessoa de Meia-Idade , Ultrassonografia
19.
PLoS One ; 15(7): e0234071, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32667926

RESUMO

The objective is to study the design method of roadway support and provide technical support for coal mining and other mining methods that need deep roadway excavation. Through literature review, the occurrence, development mechanism and influencing factors of surrounding loose rock zones of roadways are analyzed. A method of detecting is selected according to the characteristics of surrounding rock loosening. Knowledge of elastoplastic mechanics is used to theoretically study the failure mechanism of surrounding rock in deep re-mining roadways. Based on the artificial neural network prediction model (ANN), the surrounding rock is classified and a support network model of the decision system is constructed. After the design of roadway support, a sharp change of vault subsidence normally occurs within about 7 days after excavation, and the total subsidence is 14 mm. In the following month, deformation is slow, subsidence is small, and it is basically stable after one month. The curve of the vault subsidence rate shows that the vault subsidence rate is less than or equal to 1mm/d after 7 days. The convergence rate is also less than 1 mm/d after 7 days. There are two cave mouths AB and CD, and the convergence value of AB is 6.47mm, CD is 10.26mm: CD is slightly larger than AB, and it is close to stable one month later. It is essentially consistent with the time of vault settlement and stability, and the amount of deformation is approximately the same. This shows that, with the advance of the working face, the displacement of the surrounding rock in the section away from the working face will gradually decrease and the surrounding rock will be stable. The stability time of surrounding rock displacement of the portal section is the same as that of vault subsidence under the initial support, and the amount of deformation is approximately the same, indicating that the support parameters and construction methods are reasonable.


Assuntos
Minas de Carvão , Técnicas de Apoio para a Decisão , Aprendizado Profundo , Engenharia/métodos , Fenômenos Geológicos , Deslizamentos de Terra , Elasticidade , Fenômenos Mecânicos , Maleabilidade
20.
Bioresour Technol ; 315: 123819, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32712513

RESUMO

This work aimed to use continuous measurements of viscoelastic properties to evaluate the effect of hydrothermal treatment on poplar samples. Different conditions (temperature and pre-soaking liquid: acidic, neutral and alkaline) were tested on wood in both tangential and radial directions. Two viscoelastic properties were determined: the modulus of elasticity and the stress relaxation. The applicability of these properties as indicators of the kinetics of biomass deconstruction was also evaluated, thanks to the chemical analyses performed on the treated solid and the recovered liquid phase. The ultimate goal is to build a macroscopic indicator capable of establishing rules to optimize the hydrothermal treatment before the explosion stage. The joint use of the two parameters succeeded in revealing the effects of chemical degradation, including the coexistence of cleavage and re-condensation and the impact of process conditions (temperature, residence time, and pre-soaking liquid). The monotonous behavior of stress relaxation is a major asset as a possible macroscopic indicator of biomass deconstruction.


Assuntos
Madeira , Biomassa , Elasticidade , Cinética , Temperatura
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