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1.
Phys Rev Lett ; 124(22): 225502, 2020 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-32567904

RESUMO

We perform molecular dynamics simulations to investigate the effect of a glass preparation on its yielding transition under oscillatory shear. We use swap Monte Carlo to investigate a broad range of glass stabilities from poorly annealed to highly stable systems. We observe a qualitative change in the nature of yielding, which evolves from ductile to brittle as glass stability increases. Our results disentangle the relative role of mechanical and thermal annealing on the mechanical properties of amorphous solids, which is relevant for various experimental situations from the rheology of soft materials to fatigue failure in metallic glasses.

2.
J Vet Med Sci ; 82(7): 948-954, 2020 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-32418945

RESUMO

The lateral cytoplasmic processes of tenocytes extend to form three-dimensional network surrounding collagen fibers. It is unknown whether connections between two cytoplasmic processes involve overlapping of the processes or merely surface contact. In this study, the two-dimensional and three-dimensional structure of tenocytes in the Achilles tendons of the newly hatched chicks were studied using transmission electron microscopy and serial block face-scanning electron microscopy. Observation of the two-dimensional structures revealed various forms of cellular connections, including connections between the cytoplasmic processes of adjacent tenocytes and between the cytoplasmic process of tenocytes and fibroblasts. Three-dimensional observation showed spike-like cytoplasmic processes extending from one tenocyte that interlocked with cytoplasmic processes from other tenocytes. Cytoplasmic processes from each tenocyte within the chick tendons interlocked to ensure a tight cell-to-cell connection around growing collagen fibers. A cellular network formed by these cytoplasmic processes surrounds each collagen fiber. Cell-cell junctions, which were suggested to be gap junctions, observed at sites of cytoplasmic process overlap most likely represent the major route for communication between tenocytes associated with fibroblasts, enabling vital signals important for maintaining the cell and tendon integrity to be transmitted.

4.
Pulm Pharmacol Ther ; 62: 101917, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32205281

RESUMO

BACKGROUND: Nintedanib is an important drug for the treatment of idiopathic pulmonary fibrosis (IPF). However, the drug is discontinued in some patients who present with diarrhea. In this study, we aimed to assess the drug continuation rate in patients who developed diarrhea during nintedanib therapy and to evaluate if antidiarrheal drugs or nintedanib dose reductions improved clinical tolerability and efficacy. METHODS: Eighty-six patients with IPF were treated in our institution between December 2015 and March 2018. Among them, 50 patients who experienced nintedanib-related diarrhea were analyzed regarding tolerability and persistence rate. RESULTS: In 50 patients who experienced nintedanib-related diarrhea, 26 (n = 11, without reduction and n = 15, with reduction) continuously received nintedanib. Meanwhile, the drug was discontinued in 24 patients (n = 13, without reduction and n = 11, with reduction). In 9 of 24 patients, the drug was discontinued due to diarrhea. The annual rate of decline in forced vital capacity and the duration of nintedanib administration were not significantly different between groups with and without dosage reduction. Moreover, 23, 13, 8, and 2 patients received 1, 2, 3, and 4 agents, respectively. Clostridium butyricum is a probiotic bacterium most commonly used as an antidiarrheal agent. In this study, it was used in 28 of 46 patients. The total durations of nintedanib administration differed significantly according to the number of antidiarrheal drugs taken: 853 ± 221 days, more than three agents; 424 ± 365 days, without an agent (p = 0.043); and 460 ± 142, one agent (p = 0.0003). CONCLUSIONS: When diarrhea occurs within a year after using nintedanib, the dose reduction may be acceptable without affecting pulmonary function. Moreover, treatment with multiple antidiarrheals may be a practical option to maintain the use of nintedanib therapy compared with monotherapy and no therapy.

5.
Food Chem ; 315: 126285, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32007816

RESUMO

Wooden breast is a common problem in the poultry industry, occurring when broiler breast meat becomes rubber-like and extremely hard. Unclear points remain regarding the mechanical strength changes caused by post-mortem biochemical changes in wooden breasts. This study aimed to investigate this knowledge gap. We found endogenous protease activity to be high in wooden breasts and observed a 30 kDa fragment of troponin T (an indicator of postmortem tenderness) from day 1 postmortem. The amount of intramuscular connective tissue in wooden breasts was greater than that of normal breast meat, particularly in the perimysium. The intramuscular connective tissue structure and quantity significantly affect the mechanical strength of meat. It became clear that the wooden breasts are much more mechanically stronger than normal breasts at postmortem day 5 because the large amount of intramuscular connective tissue in the wooden breasts has hardly changed even 5 days postmortem.


Assuntos
Carne/análise , Animais , Galinhas , Tecido Conjuntivo , Músculo Esquelético , Mudanças Depois da Morte
6.
Phys Rev Lett ; 124(5): 058001, 2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32083930

RESUMO

We show that non-Brownian suspensions of repulsive spheres below jamming display a slow relaxational dynamics with a characteristic timescale that diverges at jamming. This slow timescale is fully encoded in the structure of the unjammed packing and can be readily measured via the vibrational density of states. We show that the corresponding dynamic critical exponent is the same for randomly generated and sheared packings. Our results show that a wide variety of physical situations, from suspension rheology to algorithmic studies of the jamming transition are controlled by a unique diverging timescale, with a universal critical exponent.

7.
Microvasc Res ; 129: 103954, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31730773

RESUMO

Group V secretory phospholipase A2 (gVPLA2) is a potent inflammatory mediator in mammalian tissues that hydrolyzes phospholipids and initiates eicosanoid biosynthesis. Previous work has demonstrated that multiple inflammatory stimuli induce its expression and secretion in several cell types, including the lung endothelium. However, little is known about the mechanism(s) by which gVPLA2 inflammatory signaling is subsequently downregulated. Therefore, in this study we characterized potential clearance mechanisms for gVPLA2 in lung endothelial cells (EC). We observed that exogenous gVPLA2 is taken up rapidly by nutrient-starved human pulmonary artery EC (HPAEC) in vitro, and its cellular expression subsequently is reduced over several hours. In parallel experiments performed in pulmonary vascular EC isolated from mice genetically deficient in gVPLA2, the degradation of exogenously applied gVPLA2 occurs in a qualitatively similar fashion. This degradation is significantly attenuated in EC treated with ammonium chloride or chloroquine, which are lysosomal inhibitors that block autophagic flux. In contrast, the proteasomal inhibitor MG132 fails to prevent the clearance of gVPLA2. Both immunofluorescence microscopy and proximity ligation assay demonstrate the co-localization of LC3 and gVPLA2 during this process, indicating the association of gVPLA2 with autophagosomes. Nutrient starvation, a known inducer of autophagy, is sufficient to stimulate gVPLA2 degradation. These results suggest that a lysosome-mediated autophagy pathway contributes to gVPLA2 clearance from lung EC. These novel observations advance our understanding of the mechanism by which this key inflammatory enzyme is downregulated in the lung vasculature.

8.
Soft Matter ; 15(38): 7557-7566, 2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31528879

RESUMO

The reversible-irreversible (RI) transition of particle trajectories in athermal colloidal suspensions under cyclic shear deformation is an archetypal nonequilibrium phase transition which has attracted much attention recently. Most studies of the RI transitions have focused on either dilute limit or very high densities well above the jamming transition point. The transition between the two limiting cases is largely unexplored. In this paper, we study the RI transition of athermal frictionless colloidal particles over a wide range of densities, with emphasis on the region below φJ, by using oscillatory sheared molecular dynamics simulation. We reveal that the nature of the RI transitions in the intermediate densities is very rich. As demonstrated by the previous work by Schreck et al. [Phys. Rev. E: Stat., Nonlinear, Soft Matter Phys., 2013, 88, 052205], there exist the point-reversible and the loop-reversible phases depending on the density and the shear strain amplitude. We find that, between the two reversible phases, a quasi-irreversible phase where the particles' trajectories are highly non-affine and diffusive. The averaged number of contacts of particles is found to characterize the phase boundaries. We also find that the system undergoes the yielding transition below but in the vicinity of φJ when the strain with a small but finite strain rate is applied. This yielding transition line matches with the RI transition line separating the loop-reversible from the irreversible phases. Surprisingly, the nonlinear rheological response called "softening" has been observed even below φJ. These findings imply that geometrical properties encoded in the sheared configurations control the dynamical transitions.

9.
Sci Rep ; 9(1): 8118, 2019 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-31148561

RESUMO

The theories of Brownian motion, the Debye rotational diffusion model, and hydrodynamics together provide us with the Stokes-Einstein-Debye (SED) relation between the rotational relaxation time of the [Formula: see text]-th degree Legendre polynomials [Formula: see text], and viscosity divided by temperature, η/T. Experiments on supercooled liquids are frequently performed to measure the SED relations, [Formula: see text]kBT/η and Dt[Formula: see text], where Dt is the translational diffusion constant. However, the SED relations break down, and its molecular origin remains elusive. Here, we assess the validity of the SED relations in TIP4P/2005 supercooled water using molecular dynamics simulations. Specifically, we demonstrate that the higher-order [Formula: see text] values exhibit a temperature dependence similar to that of η/T, whereas the lowest-order [Formula: see text] values are decoupled with η/T, but are coupled with the translational diffusion constant Dt. We reveal that the SED relations are so spurious that they significantly depend on the degree of Legendre polynomials.

10.
J Chem Phys ; 150(12): 124504, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30927885

RESUMO

We construct a linear response theory of applying shear deformations from boundary walls in the film geometry in Kubo's theoretical scheme. Our method is applicable to any solids and fluids. For glasses, we assume quasi-equilibrium around a fixed inherent state. Then, we obtain linear-response expressions for any variables including the stress and the particle displacements, even though the glass interior is elastically inhomogeneous. In particular, the shear modulus can be expressed in terms of the correlations between the interior stress and the forces from the walls. It can also be expressed in terms of the inter-particle correlations, as has been shown in the previous literature. Our stress relaxation function includes the effect of the boundary walls and can be used for inhomogeneous flow response. We show the presence of long-ranged, long-lived correlations among the fluctuations of the forces from the walls and the displacements of all the particles in the cell. We confirm these theoretical results numerically in a two-dimensional model glass. As an application, we describe emission and propagation of transverse sounds after boundary wall motions using these time-correlation functions. We also find resonant sound amplification when the frequency of an oscillatory shear approaches that of the first transverse sound mode.

11.
Ultramicroscopy ; 202: 107-113, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31005817

RESUMO

In this paper we discuss probe properties in terms of probe currents, probe sizes, energy spread, virtual source sizes, and brightness in a 1.2-MV cold field-emission (cold FE) transmission electron microscope (TEM) equipped with a magnetic gun lens. The probe size increased gradually in proportion to the (3/8)th power of the probe current, very unusual behavior in cold FE guns but typical behavior in thermionic guns. This is due to the magnetic gun lens, which caused large emission angles for electron beams in the probe before being limited by aberrations at the gun and acceleration tube. The brightness reached the maximum at 1.62 × 1014 A/(m2sr) and then decreased with increasing the emission current. The energy spread of the beam, including the Boersch effect, was 0.32-0.50 eV, comparable to that of conventional cold FE guns without magnetic gun lens. Experimental analysis indicated that neither noises nor aberrations caused the probe size increase under the optimized illumination condition. The virtual source size increased from 11.1 to 24.7 nm with the increase in the emission current. To describe this behavior, we conjecture that this brightness reduction is due to increase in the virtual source size caused by trajectory displacement created by stochastic Coulomb interactions near the emitter.

12.
J Chem Phys ; 150(7): 074503, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30795681

RESUMO

We numerically investigate the slow dynamics of a binary mixture of ultrasoft particles interacting with the generalized Hertzian potential. If the softness parameter, α, is small, the particles at high densities start penetrating each other, form clusters, and eventually undergo the glass transition. We find multiple cluster-glass phases characterized by a different number of particles per cluster, whose boundary lines are sharply separated by the cluster size. Anomalous logarithmic slow relaxation of the density correlation functions is observed in the vicinity of these glass-glass phase boundaries, which hints the existence of the higher-order dynamical singularities predicted by the mode-coupling theory. Deeply in the cluster glass phases, it is found that the dynamics of a single particle is decoupled from that of the collective fluctuations.

13.
Phys Rev Lett ; 123(26): 265501, 2019 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-31951456

RESUMO

If a liquid is cooled rapidly to form a glass, its structural relaxation becomes retarded, producing a drastic increase in viscosity. In two dimensions, strong long-wavelength fluctuations persist, even at low temperature, making it difficult to evaluate the microscopic structural relaxation time. This Letter shows that, in a 2D glass-forming liquid, relative displacement between neighbor particles yields a relaxation time that grows in proportion to the viscosity. In addition to thermal elastic vibrations, hydrodynamic fluctuations are found to affect the long-wavelength dynamics, yielding a logarithmically diverging diffusivity in the long-time limit.

14.
PLoS Comput Biol ; 14(11): e1006545, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30395600

RESUMO

Modeling the complex collective behavior is a challenging issue in several material and life sciences. The collective motion has been usually modeled by simple interaction rules and explained by global statistics. However, it remains difficult to bridge the gap between the dynamic properties of the complex interaction and the emerging group-level functions. Here we introduce decomposition methods to directly extract and classify the latent global dynamics of nonlinear dynamical systems in an equation-free manner, even including complex interaction in few data dimensions. We first verified that the basic decomposition method can extract and discriminate the dynamics of a well-known rule-based fish-schooling (or bird-flocking) model. The method extracted different temporal frequency modes with spatial interaction coherence among three distinct emergent motions, whereas these wave properties in multiple spatiotemporal scales showed similar dispersion relations. Second, we extended the basic method to map high-dimensional feature space for application to actual small-dimensional systems complexly changing the interaction rules. Using group sports human data, we classified the dynamics and predicted the group objective achievement. Our methods have a potential for classifying collective motions in various domains which obey in non-trivial dominance law known as active matters.


Assuntos
Processos Grupais , Modelos Biológicos , Movimento (Física) , Dinâmica não Linear , Algoritmos , Humanos , Esportes
15.
Am J Physiol Lung Cell Mol Physiol ; 315(5): L834-L845, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30188745

RESUMO

Acute respiratory distress syndrome (ARDS) is a severe clinical condition marked by acute respiratory failure and dysregulated inflammation. Pulmonary vascular endothelial cells (PVECs) function as an important pro-inflammatory source in ARDS, suggesting that modulation of inflammatory events at the endothelial level may have a therapeutic benefit. Dipeptidyl peptidase-4 (DPP4) inhibitors, widely used for the treatment of diabetes mellitus, have been reported to have possible anti-inflammatory effects. However, the potential anti-inflammatory effects of DPP4 inhibition on PVEC function and ARDS pathophysiology are unknown. Therefore, we evaluated the effects of sitagliptin, a DPP4 inhibitor in wide clinical use, on LPS-induced lung injury in mice and in human lung ECs in vitro. In vivo, sitagliptin reduced serum DPP4 activity, bronchoalveolar lavage protein concentration, cell number, and proinflammatory cytokine levels after LPS and alleviated histological findings of lung injury. LPS decreased the expression levels of CD26/DPP4 on pulmonary epithelial cells and PVECs isolated from mouse lungs, and the effect was partially reversed by sitagliptin. In vitro, human lung microvascular ECs (HLMVECs) expressed higher levels of CD26/DPP4 than human pulmonary arterial ECs. LPS induced the release of TNFα, IL-6, and IL-8 by HLMVECs that were inhibited by sitagliptin. LPS promoted the proliferation of HLMVECs, and sitagliptin suppressed this response. However, sitagliptin failed to reverse LPS-induced permeability in cultured ECs or lung epithelial cells in vitro. In summary, sitagliptin attenuates LPS-induced lung injury in mice and exerts anti-inflammatory effects on HLMVECs. These novel observations indicate DPP4 inhibitors may have potential as therapeutic drugs for ARDS.


Assuntos
Dipeptidil Peptidase 4/metabolismo , Inibidores da Dipeptidil Peptidase IV/farmacologia , Lipopolissacarídeos/farmacologia , Síndrome do Desconforto Respiratório do Adulto/induzido quimicamente , Síndrome do Desconforto Respiratório do Adulto/tratamento farmacológico , Fosfato de Sitagliptina/farmacologia , Animais , Lavagem Broncoalveolar/métodos , Proliferação de Células/efeitos dos fármacos , Citocinas/metabolismo , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/metabolismo , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Feminino , Humanos , Inflamação/tratamento farmacológico , Inflamação/metabolismo , Pulmão/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Síndrome do Desconforto Respiratório do Adulto/metabolismo
16.
Phys Rev E ; 98(1-1): 012609, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30110811

RESUMO

Discontinuous shear thickening in dense suspensions naturally emerges from the activation of frictional forces by shear flow in non-Brownian systems close to jamming. Yet, this physical picture is incomplete as most experiments study soft colloidal particles subject to thermal fluctuations. To characterize discontinuous shear thickening in colloidal suspensions, we use computer simulations to provide a complete description of the competition between athermal jamming, frictional forces, thermal motion, particle softness, and shear flow. We intentionally neglect hydrodynamics, electrostatics, lubrication, and inertia, but can nevertheless achieve quantitative agreement with experimental findings. In particular, shear thickening corresponds to a crossover between frictionless and frictional jamming regimes which is controlled by thermal fluctuations and particle softness and occurs at a softness dependent Péclet number. We also explore the consequences of our findings for constant pressure experiments, and critically discuss the reported emergence of "S-shaped" flow curves. Our work provides the minimal ingredients to quantitatively interpret a large body of experimental work on discontinuous shear thickening in colloidal suspensions.

17.
PLoS One ; 13(2): e0193307, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29474396

RESUMO

The high incidence of meat of impaired quality poses a serious problem in the poultry industry. In recent years, the incidence of the pectoralis major muscle that appeared pale colored, remarkably hardened, and exudative, called "wooden breast" or "woody breast" has increased in slaughter houses. In the present study, 19-day-old Ross 308 broiler chickens affected (n = 10) and unaffected (n = 10) with remarkably hardened breast were selected from a commercial broiler farm, and reared to 55 days of age under a controlled environment. Among the affected birds, 5 of 10 birds appeared exhausted with markedly suppressed weight gain and 4 of 10 birds died during the rearing period. In contrast, all unaffected birds survived and most gained weight. Four of 10 unaffected birds lost the ability of back-to-back wing contact by the late stage of rearing. The biochemical analysis of blood plasma samples of 20-day-old birds revealed that creatine kinase and L-aspartate aminotransferase values in most affected birds were higher than those in unaffected birds; however, these values in unaffected birds increased rapidly with lost wing contactability and increasing age. Postmortem examinations revealed that the mean diameter of myofibers in affected birds was smaller than that in unaffected birds. Moreover, symptoms of degenerative and regenerative muscles were observed in most birds in both groups. Among them, a decrease in, or defect of, the characteristic polygonal shape of myofibers was the most common change within the pectoralis major muscles in both groups. The present study demonstrated that broilers affected with remarkably hardened breast during the middle stage of rearing would have suppressed physical status and weight gain, or would die. It was suggested that rapid growth in broilers might be a cause of remarkably hardened breast.


Assuntos
Criação de Animais Domésticos , Aspartato Aminotransferases/sangue , Proteínas Aviárias/sangue , Galinhas/crescimento & desenvolvimento , Creatina Quinase/sangue , Doenças Musculares , Doenças das Aves Domésticas , Animais , Feminino , Masculino , Doenças Musculares/sangue , Doenças Musculares/patologia , Doenças Musculares/fisiopatologia , Doenças das Aves Domésticas/sangue , Doenças das Aves Domésticas/patologia , Doenças das Aves Domésticas/fisiopatologia
18.
J Phys Condens Matter ; 30(9): 094004, 2018 03 07.
Artigo em Inglês | MEDLINE | ID: mdl-29345245

RESUMO

It has recently been revealed that long-wavelength fluctuation exists in two-dimensional (2D) glassy systems, having the same origin as that given by the Mermin-Wagner theorem for 2D crystalline solids. In this paper, we discuss how to characterise quantitatively the long-wavelength fluctuation in a molecular dynamics simulation of a lightly supercooled liquid. We employ the cage-relative mean-square displacement (MSD), defined on relative displacement to its cage, to quantitatively separate the long-wavelength fluctuation from the original MSD. For increasing system size the amplitude of acoustic long wavelength fluctuations not only increases but shifts to later times causing a crossover with structural relaxation of caging particles. We further analyse the dynamic correlation length using the cage-relative quantities. It grows as the structural relaxation becomes slower with decreasing temperature, uncovering an overestimation by the four-point correlation function due to the long-wavelength fluctuation. These findings motivate the usage of cage-relative MSD as a starting point for analysis of 2D glassy dynamics.

19.
Sci Adv ; 3(8): e1700399, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28835918

RESUMO

The violation of the Stokes-Einstein (SE) relation D ~ (η/T)-1 between the shear viscosity η and the translational diffusion constant D at temperature T is of great importance for characterizing anomalous dynamics of supercooled water. Determining which time scales play key roles in the SE violation remains elusive without the measurement of η. We provide comprehensive simulation results of the dynamic properties involving η and D in the TIP4P/2005 supercooled water. This enabled the thorough identification of the appropriate time scales for the SE relation Dη/T. In particular, it is demonstrated that the temperature dependence of various time scales associated with structural relaxation, hydrogen bond breakage, stress relaxation, and dynamic heterogeneities can be definitely classified into only two classes. That is, we propose the generalized SE relations that exhibit "violation" or "preservation." The classification depends on the examined time scales that are coupled or decoupled with the diffusion. On the basis of the classification, we explain the physical origins of the violation in terms of the increase in the plateau modulus and the nonexponentiality of stress relaxation. This implies that the mechanism of SE violation is attributed to the attained solidity upon supercooling, which is in accord with the growth of non-Gaussianity and spatially heterogeneous dynamics.

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