Myocardial fibrosis after myocardial infarction (MI) is a leading cause of heart diseases. MI activates cardiac fibroblasts (CFs) and promotes CF to myofibroblast transformation (CMT). This study ...aimed to investigate the role of miR‐21 in the regulation of CMT and myocardial fibrosis. Primary rat CFs were isolated from young SD rats and treated with TGF‐β1, miR‐21 sponge or Jagged1 siRNA. Cell proliferation, invasion and adhesion were detected. MI model was established in male SD rats using LAD ligation method and infected with recombinant adenovirus. The heart function and morphology was evaluated by ultrasonic and histological analysis. We found that TGF‐β1 induced the up‐regulation of miR‐21 and down‐regulation of Jagged1 in rat CFs. Luciferase assay showed that miR‐21 targeted 3′‐UTR of Jagged1 in rat CFs. miR‐21 sponge inhibited the transformation of rat CFs into myofibroblasts, and abolished the inhibition of Jagged1 mRNA and protein expression by TGF‐β1. Furthermore, these effects of miR‐21 sponge on rat CFS were reversed by siRNA mediated knockdown of Jagged1. In vivo, heart dysfunction and myocardial fibrosis in MI model rats were partly improved by miR‐21 sponge but were aggravated by Jagged1 knockdown. Taken together, these results suggest that miR‐21 promotes cardiac fibroblast‐to‐myofibroblast transformation and myocardial fibrosis by targeting Jagged1. miR‐21 and Jagged1 are potential therapeutic targets for myocardial fibrosis.
Lamellar molybdenum disulfide (MoS2) has attracted a wide range of research interests in recent years because of its two‐dimensional layered structure, ultrathin thickness, large interlayer distance, ...adjustable band gap, and capability to form different crystal structures. These special characteristics and high anisotropy have made MoS2 widely applicable in energy storage and harvesting. In this Minireview, a systematic and comprehensive introduction to MoS2, as well as its composites, is presented. It is aimed to summarize the various synthetic methods of MoS2‐based composites and their application in energy‐storage devices (lithium‐ion batteries, sodium‐ion batteries, lithium–sulfur batteries, and supercapacitors) in detail. Based on recent studies, this Minireview provides important and comprehensive guidelines for further study and development efforts in the MoS2 in energy‐storage field.
Power beyond the plane: MoS2‐based materials show great potential in the energy‐storage field with high capacity and stability. This review summarizes different synthetic methods and advances in lithium‐ion batteries, sodium‐ion batteries, lithium–sulfur batteries, supercapacitors, and other batteries for energy‐storage applications.
Photodynamic therapy (PDT) of cancer is limited by tumor hypoxia. Platinum nanoparticles (nano‐Pt) as a catalase‐like nanoenzyme can enhance PDT through catalytic oxygen supply. However, the ...cytotoxic activity of nano‐Pt is not comprehensively considered in the existing methods to exert their multifunctional antitumor effects. Here, nano‐Pt are loaded into liposomes via reverse phase evaporation. The clinical photosensitizer verteporfin (VP) is loaded in the lipid bilayer to confer PDT activity. Murine macrophage cell membranes are hybridized into the liposomal membrane to confer biomimetic and targeting features. The resulting liposomal system, termed “nano‐Pt/VP@MLipo,” is investigated for chemophototherapy in vitro and in vivo in mouse tumor models. At the tumor site, oxygen produced by nano‐Pt catalyzation improves the VP‐mediated PDT, which in turn triggers the release of nano‐Pt via membrane permeabilization. The ultrasmall 3–5 nm nano‐Pt enables better penetration in tumors, which is also facilitated by the generated oxygen gas, for enhanced chemotherapy. Chemophototherapy with a single injection of nano‐Pt/VP@MLipo and light irradiation inhibits the growth of aggressive 4T1 tumors and their lung metastasis, and prolongs animal survival without overt toxicity.
The biomimetic liposomal nano‐Pt (nano‐Pt/VP@MLipo) targets the tumor sites, where oxygen produced by nano‐Pt catalyzation enhances the verteporfin (VP)‐mediated photodynamic therapy (PDT). PDT in turn permeabilizes the liposome membrane for efficient nano‐Pt release. These ultrasmall particles (3–5 nm) achieve penetration in deeper tumor tissue, which is also facilitated by the generated oxygen gas, for enhanced chemotherapy.
Dynamic tracking of human sperms across a large volume is a challenging task. To provide a high-throughput solution to this important need, here we describe a lensfree on-chip imaging technique that ...can track the three-dimensional (3D) trajectories of > 1,500 individual human sperms within an observation volume of approximately 8–17 mm ³. This computational imaging platform relies on holographic lensfree shadows of sperms that are simultaneously acquired at two different wavelengths, emanating from two partially-coherent sources that are placed at 45° with respect to each other. This multiangle and multicolor illumination scheme permits us to dynamically track the 3D motion of human sperms across a field-of-view of > 17 mm ² and depth-of-field of approximately 0.5–1 mm with submicron positioning accuracy. The large statistics provided by this lensfree imaging platform revealed that only approximately 4–5% of the motile human sperms swim along well-defined helices and that this percentage can be significantly suppressed under seminal plasma. Furthermore, among these observed helical human sperms, a significant majority (approximately 90%) preferred right-handed helices over left-handed ones, with a helix radius of approximately 0.5–3 μm, a helical rotation speed of approximately 3–20 rotations/s and a linear speed of approximately 20–100 μm/s. This high-throughput 3D imaging platform could in general be quite valuable for observing the statistical swimming patterns of various other microorganisms, leading to new insights in their 3D motion and the underlying biophysics.
Nanopore-based sensors have established themselves as a prominent tool for solution-based, single-molecule analysis of the key building blocks of life, including nucleic acids, proteins, glycans and ...a large pool of biomolecules that have an essential role in life and healthcare. The predominant molecular readout method is based on measuring the temporal fluctuations in the ionic current through the pore. Recent advances in materials science and surface chemistries have not only enabled more robust and sensitive devices but also facilitated alternative detection modalities based on field-effect transistors, quantum tunnelling and optical methods such as fluorescence and plasmonic sensing. In this Review, we discuss recent advances in nanopore fabrication and sensing strategies that endow nanopores not only with sensitivity but also with selectivity and high throughput, and highlight some of the challenges that still need to be addressed.Nanopore sensors enable the solution-based analysis of nucleic acids, proteins and other biomolecules at the single-molecule level. This Review discusses new fabrication and sensing strategies — including field-effect transistors, quantum tunnelling and optical methods — that enhance the sensitivity and selectivity of nanopores.
Monolayer KAgX are a class of novel two-dimensional (2D) layered materials with efficient optical absorption and superior carrier mobility, signifying their potential application prospect in ...photovoltaic (PV) and thermoelectric (TE) fields. Motivated by the recent theoretical studies on the KAgX monolayer, we carried out systematic investigations on the TE performance of KAgS and KAgSe monolayers, employing density functional theory (DFT) and semiclassical Boltzmann transport equation (BTE). For both KAgSe and KAgS monolayers, large Grüneisen parameters, low group velocities, and short phonon scattering time greatly hinder their heat transport and result in an ultralow thermal conductivity, 0.26 and 0.33 W m–1 K–1 at 300 K, respectively. A twofold degeneracy appearing at the Γ point and the abrupt slope of the density of states (DOS) near the Fermi level give rise to high Seebeck coefficients of KAgX monolayers. Due to the ultralow thermal conductivity and excellent electronic transport performance, the ZT values as high as 4.65 (3.11) and 4.05 (2.63) at 500 (300) K in the n-type doping for KAgSe and KAgS monolayers are obtained. The exceptional performance of KAgX monolayers sheds light on their immense potential applications in the medium-temperature (around 300–500 K) thermoelectric devices and greatly stimulates further experimental synthesis and validation.
The boundary element method of peridynamics Liang, Xue; Wang, Linjuan; Xu, Jifeng ...
International journal for numerical methods in engineering,
30 October 2021, Letnik:
122, Številka:
20
Journal Article
Recenzirano
Odprti dostop
The peridynamic theory brings advantages in dealing with discontinuities, dynamic loading, and nonlocality. The integro‐differential formulation of peridynamics poses challenges to numerical ...solutions of complicated and practical problems. Some important issues attract much attention, such as the computation of infinite domains, the treatment of softening of boundaries due to an incomplete horizon, and time accumulation error in dynamic processes. In this work, we develop the boundary element method of peridynamics (PD‐BEM). The numerical examples demonstrate that the PD‐BEM exhibits several features. First, for nondestructive cases, the PD‐BEM can be one to two orders of magnitude faster than the meshless particle method of peridynamics (PD‐MPM) that directly discretizes the computational domains; second, it eliminates the time accumulation error, and thus conserves the total energy much better than the PD‐MPM; third, it does not exhibit spurious boundary softening phenomena. For destructive cases where new boundaries emerge during the loading process, we propose a coupling scheme where the PD‐MPM is applied to the cracked region and the PD‐BEM is applied to the uncracked region such that the time of computation can be significantly reduced.
Recent development of damage plasticity theory shows the critical plastic strain at fracture for ductile solids depends on the pressure and the Lode angle on the octahedral plane along the loading ...path. The determination of the fracture strain envelope is usually a difficult and time consuming process. This is due to the experimental difficulties in maintaining a constant pressure and Lode angle at the fracture site, which is further complicated by the coupled nature of the parameters to be calibrated and the geometrical localization of the deformation. The fracture strain envelope is one of the key ingredients of the damage plasticity theory and relates to the accuracy of predicted results. In the present paper, the Lode angle dependence and the pressure sensitivity functions for the fracture strain envelope are derived from the hardening rule of the matrix using Tresca type fracture condition and Drucker–Prager formula, respectively. Quantitative analyses of Clausing’s and Bridgman’s test data are presented. Then a pressure modified maximum shear stress condition is adopted as fracture initiation condition to examine their joint effects on the fracture strain envelope. The relationship of the strain hardening, the pressure sensitivity and the Lode angle dependence are examined and verified by existing experimental results. We show that within the moderate range of stress triaxiality, the pressure modified maximum shear condition can be used as the fracture stress envelope for ductile metals within the framework of damage plasticity. The present method reduces significantly the amount of work to calibrate the material parameters for ductile fracture.
Orthogonal designs have been used as space-time block codes for wireless communications with multiple transmit antennas, which can achieve full transmit diversity and have a very simple decoupled ...maximum-likelihood decoding algorithm. The rate of an orthogonal design is defined as the ratio of the number of transmitted information symbols in a block of channel uses to the length of the given block, which reflects the bandwidth efficiency of the employed space-time block code constructed from the orthogonal design. This paper focuses on the analysis and synthesis of orthogonal designs with the maximum possible rates, which may be real or complex and square or rectangular matrices. We first provide several representations of orthogonal designs and their characterizations in terms of Hurwitz-Radon matrix equations. Next, we observe that the real orthogonal designs, square or rectangular, and the complex square orthogonal designs with maximal rates have been well understood from the existing results in the mathematics literature which can be dated back to 1890s. However, unfortunately, it is not the case for the complex rectangular orthogonal designs with rates as high as possible. We then construct a class of complex orthogonal designs for any number of transmit antennas. The proposed complex orthogonal designs for the number of transmit antennas n=2m-1 and 2m have the same rate m+1 and 2m, where m is any natural number. Finally, we demonstrate that, for n=2m-1 and 2m with any given natural number m, the value m+1 and 2m is the maximum possible rate that the complex orthogonal designs, square or rectangular, with n transmit antennas can achieve.
Single‐cell RNA sequencing (scRNA‐seq) technology has become the state‐of‐the‐art approach for unravelling the heterogeneity and complexity of RNA transcripts within individual cells, as well as ...revealing the composition of different cell types and functions within highly organized tissues/organs/organisms. Since its first discovery in 2009, studies based on scRNA‐seq provide massive information across different fields making exciting new discoveries in better understanding the composition and interaction of cells within humans, model animals and plants. In this review, we provide a concise overview about the scRNA‐seq technology, experimental and computational procedures for transforming the biological and molecular processes into computational and statistical data. We also provide an explanation of the key technological steps in implementing the technology. We highlight a few examples on how scRNA‐seq can provide unique information for better understanding health and diseases. One important application of the scRNA‐seq technology is to build a better and high‐resolution catalogue of cells in all living organism, commonly known as atlas, which is key resource to better understand and provide a solution in treating diseases. While great promises have been demonstrated with the technology in all areas, we further highlight a few remaining challenges to be overcome and its great potentials in transforming current protocols in disease diagnosis and treatment.
This review provides a concise summary of the single‐cell RNA sequencing technologies.
Overview and guidelines for planning experimental procedures are presented.
Bioinformatics tools for scRNA‐seq data analysis are thoroughly discussed.
Applications and further development of scRNA‐seq technology are highlighted.
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