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•Schiff-base functionalized magnetic Fe3O4 composites were synthesized by different methods.•The magnetic composites were promising adsorbents for the removal of Pb(II) and ...Cd(II).•Kinetic adsorption followed pseudo-second-order model and dominated by film diffusion process.•The adsorption process was spontaneous, endothermic, random increase, and chemical in nature.•The adsorption mechanism was revealed combined experimental and theoretical method.
Schiff-base functionalized superparamagnetic Fe3O4 composites (Fe3O4@SiO2-HO-S and Fe3O4@SiO2-HE-S) were synthesized by homogeneous and heterogeneous method, respectively. Their structures were characterized by FTIR, elemental analysis, SEM, TEM, TGA, XRD, and porous structure analysis. The feasibility of Fe3O4@SiO2-HO-S and Fe3O4@ SiO2-HE-S for the removal of Pb(II) and Cd(II) from aqueous solution was systematically investigated. The effects of pH, time, temperature, and initial metal ions concentration on the adsorption were determined. Results demonstrated that the optimal adsorption pH for both Pb(II) and Cd(II) is 6. Adsorption kinetic showed that the adsorption equilibrium time for Pb(II) and Cd(II) are 270 and 210 min, respectively. Adsorption kinetic followed pseudo-second order model and dominated by film diffusion process. Isotherm adsorption indicated that the adsorption capacity increased with the increase of metal ion concentration and temperature. The isotherm adsorption process can be well depicted by Langmuir isotherm model. Thermodynamic parameters indicated that the adsorption process is spontaneous, endothermic, and randomness-increasing process. FTIR and DFT calculation demonstrated the interaction between N atom and metal ion dominated the adsorption of Pb(II) and Cd(II), while O atom also participated in the coordination. Charge transfer occurred from Schiff base ligand to Pb(II) and Cd(II) during the adsorption process.
Cardiovascular diseases have become the leading cause of human death. Aging is an independent risk factor for cardiovascular diseases. Cardiac aging is associated with maladaptation of cellular ...metabolism, dysfunction (or senescence) of cardiomyocytes, a decrease in angiogenesis, and an increase in tissue scarring (fibrosis). These events eventually lead to cardiac remodeling and failure. Senescent cardiomyocytes show the hallmarks of DNA damage, endoplasmic reticulum stress, mitochondria dysfunction, contractile dysfunction, hypertrophic growth, and senescence-associated secreting phenotype (SASP). Metabolism within cardiomyocytes is essential not only to fuel the pump function of the heart but also to maintain the functional homeostasis and participate in the senescence of cardiomyocytes. The senescence of cardiomyocyte is also regulated by the non-myocytes (endothelial cells, fibroblasts, and immune cells) in the local microenvironment. On the other hand, the senescent cardiomyocytes alter their phenotypes and subsequently affect the non-myocytes in the local microenvironment and contribute to cardiac aging and pathological remodeling. In this review, we first summarized the hallmarks of the senescence of cardiomyocytes. Then, we discussed the metabolic switch within senescent cardiomyocytes and provided a discussion of the cellular communications between dysfunctional cardiomyocytes and non-myocytes in the local microenvironment. We also addressed the functions of metabolic regulators within non-myocytes in modulating myocardial microenvironment. Finally, we pointed out some interesting and important questions that are needed to be addressed by further studies.
Due to the scarcity of circular polarization light sources, linear-to-circular polarization conversion is required to generate circularly polarized light for a variety of applications. Despite ...significant past efforts, broadband linear-to-circular polarization conversion remains elusive particularly in the terahertz and midinfrared frequency ranges. Here we propose a novel mechanism based on coupled mode theory, and experimentally demonstrate at terahertz frequencies that highly efficient (power conversion efficiency approaching unity) and ultrabroadband (fractional bandwidth up to 80%) linear-to-circular polarization conversion can be accomplished by the judicious design of birefringent metasurfaces. The underlying mechanism operates in the frequency range between well separated resonances, and relies upon the phase response of these resonances away from the resonant frequencies, as well as the balance of the resonant and nonresonant channels. This mechanism is applicable for any operating frequencies from microwave to visible. The present Letter potentially opens a wide range of opportunities in wireless communications, spectroscopy, and emergent quantum materials research where circularly polarized light is desired.
Emerging photonic functionalities are mostly governed by the fundamental principle of Lorentz reciprocity. Lifting the constraints imposed by this principle could circumvent deleterious effects that ...limit the performance of photonic systems. Most efforts to date have been limited to waveguide platforms. Here, we propose and experimentally demonstrate a spatio-temporally modulated metasurface capable of complete violation of Lorentz reciprocity by reflecting an incident beam into far-field radiation in forward scattering, but into near-field surface waves in reverse scattering. These observations are shown both in nonreciprocal beam steering and nonreciprocal focusing. We also demonstrate nonreciprocal behavior of propagative-only waves in the frequency- and momentum-domains, and simultaneously in both. We develop a generalized Bloch-Floquet theory which offers physical insights into Lorentz nonreciprocity for arbitrary spatial phase gradients, and its predictions are in excellent agreement with experiments. Our work opens exciting opportunities in applications where free-space nonreciprocal wave propagation is desired.
Pathological cardiac hypertrophy induced by stresses such as aging and neurohumoral activation is an independent risk factor for heart failure and is considered a target for the treatment of heart ...failure. However, the mechanisms underlying pathological cardiac hypertrophy remain largely unknown. We aimed to investigate the roles of SIRT2 in aging-related and angiotensin II (Ang II)-induced pathological cardiac hypertrophy.
Male C57BL/6J wild-type and
knockout mice were subjected to the investigation of aging-related cardiac hypertrophy. Cardiac hypertrophy was also induced by Ang II (1.3 mg/kg/d for 4 weeks) in male C57BL/6J
knockout mice, cardiac-specific
transgenic (
-Tg) mice, and their respective littermates (8 to ≈12 weeks old). Metformin (200 mg/kg/d) was used to treat wild-type and
knockout mice infused with Ang II. Cardiac hypertrophy, fibrosis, and cardiac function were examined in these mice.
SIRT2 protein expression levels were downregulated in hypertrophic hearts from mice.
knockout markedly exaggerated cardiac hypertrophy and fibrosis and decreased cardiac ejection fraction and fractional shortening in aged (24-month-old) mice and Ang II-infused mice. Conversely, cardiac-specific
overexpression protected the hearts against Ang II-induced cardiac hypertrophy and fibrosis and rescued cardiac function. Mechanistically, SIRT2 maintained the activity of AMP-activated protein kinase (AMPK) in aged and Ang II-induced hypertrophic hearts in vivo as well as in cardiomyocytes in vitro. We identified the liver kinase B1 (LKB1), the major upstream kinase of AMPK, as the direct target of SIRT2. SIRT2 bound to LKB1 and deacetylated it at lysine 48, which promoted the phosphorylation of LKB1 and the subsequent activation of LKB1-AMPK signaling. Remarkably, the loss of SIRT2 blunted the response of AMPK to metformin treatment in mice infused with Ang II and repressed the metformin-mediated reduction of cardiac hypertrophy and protection of cardiac function.
SIRT2 promotes AMPK activation by deacetylating the kinase LKB1. Loss of SIRT2 reduces AMPK activation, promotes aging-related and Ang II-induced cardiac hypertrophy, and blunts metformin-mediated cardioprotective effects. These findings indicate that SIRT2 will be a potential target for therapeutic interventions in aging- and stress-induced cardiac hypertrophy.
Oxidative stress contributes to the development of cardiac hypertrophy and heart failure. One of the mitochondrial sirtuins, Sirt4, is highly expressed in the heart, but its function remains unknown. ...The aim of the present study was to investigate the role of Sirt4 in the pathogenesis of pathological cardiac hypertrophy and the molecular mechanism by which Sirt4 regulates mitochondrial oxidative stress.
Male C57BL/6 Sirt4 knockout mice, transgenic (Tg) mice exhibiting cardiac-specific overexpression of Sirt4 (Sirt4-Tg) and their respective controls were treated with angiotensin II (Ang II, 1.1 mg/kg/day). At 4 weeks, hypertrophic growth of cardiomyocytes, fibrosis and cardiac function were analysed. Sirt4 deficiency conferred resistance to Ang II infusion by significantly suppressing hypertrophic growth, and the deposition of fibrosis. In Sirt4-Tg mice, aggravated hypertrophy and reduced cardiac function were observed compared with non-Tg mice following Ang II treatment. Mechanistically, Sirt4 inhibited the binding of manganese superoxide dismutase (MnSOD) to Sirt3, another member of the mitochondrial sirtuins, and increased MnSOD acetylation levels to reduce its activity, resulting in elevated reactive oxygen species (ROS) accumulation upon Ang II stimulation. Furthermore, inhibition of ROS with manganese 5, 10, 15, 20-tetrakis-(4-benzoic acid) porphyrin, a mimetic of SOD, blocked the Sirt4-mediated aggravation of the hypertrophic response in Ang II-treated Sirt4-Tg mice.
Sirt4 promotes hypertrophic growth, the generation of fibrosis and cardiac dysfunction by increasing ROS levels upon pathological stimulation. These findings reveal a role of Sirt4 in pathological cardiac hypertrophy, providing a new potential therapeutic strategy for this disease.
Sirtuins and Insulin Resistance Zhou, Shuang; Tang, Xiaoqiang; Chen, Hou-Zao
Frontiers in endocrinology (Lausanne),
12/2018, Letnik:
9
Journal Article
Recenzirano
Odprti dostop
The mammalian Sirtuins (SIRT1-7) are an evolutionarily conserved family of NAD
-dependent deacylase and mono-ADP-ribosyltransferase. Sirtuins display distinct subcellular localizations and functions ...and are involved in cell survival, senescence, metabolism and genome stability. Among the mammalian Sirtuins, SIRT1 and SIRT6 have been thoroughly investigated and have prominent metabolic regulatory roles. Moreover, SIRT1 and SIRT6 have been implicated in obesity, insulin resistance, type 2 diabetes mellitus (T2DM), fatty liver disease and cardiovascular diseases. However, the roles of other Sirtuins are not fully understood. Recent studies have shown that these Sirtuins also play important roles in inflammation, mitochondrial dysfunction, and energy metabolism. Insulin resistance is the critical pathological trait of obesity and metabolic syndrome as well as the core defect in T2DM. Accumulating clinical and experimental animal evidence suggests the potential roles of the remaining Sirtuins in the regulation of insulin resistance through diverse biological mechanisms. In this review, we summarize recent advances in the understanding of the functions of Sirtuins in various insulin resistance-associated physiological processes, including inflammation, mitochondrial dysfunction, the insulin signaling pathway, glucose, and lipid metabolism. In addition, we highlight the important gaps that must be addressed in this field.
Complex multiphase nanocomposite designs present enormous opportunities for developing next‐generation integrated photonic and electronic devices. Here, a unique three‐phase nanostructure combining a ...ferroelectric BaTiO3, a wide‐bandgap semiconductor of ZnO, and a plasmonic metal of Au toward multifunctionalities is demonstrated. By a novel two‐step templated growth, a highly ordered Au–BaTiO3–ZnO nanocomposite in a unique “nanoman”‐like form, i.e., self‐assembled ZnO nanopillars and Au nanopillars in a BaTiO3 matrix, is realized, and is very different from the random three‐phase ones with randomly arranged Au nanoparticles and ZnO nanopillars in the BaTiO3 matrix. The ordered three‐phase “nanoman”‐like structure provides unique functionalities such as obvious hyperbolic dispersion in the visible and near‐infrared regime enabled by the highly anisotropic nanostructures compared to other random structures. Such a self‐assembled and ordered three‐phase nanocomposite is obtained through a combination of vapor–liquid–solid (VLS) and two‐phase epitaxy growth mechanisms. The study opens up new possibilities in the design, growth, and application of multiphase structures and provides a new approach to engineer the ordering of complex nanocomposite systems with unprecedented control over electron–light–matter interactions at the nanoscale.
A highly ordered self‐assembled Au–BaTiO3–ZnO nanocomposite is demonstrated, obtained through a combination of vapor–liquid–solid (VLS) and two‐phase epitaxy growth mechanisms. The ordered three‐phase “nanoman”‐like structure provides unique functionalities such as obvious hyperbolic dispersion in the visible and near infrared regime enabled by the highly anisotropic nanostructures in addition to the ferroelectric and plasmonic response.
Arbitrary control of terahertz (THz) waves remains a significant challenge although it promises many important applications. Here, a method to tailor the reflection and scattering of THz waves in an ...anomalous manner by using 1‐bit coding metamaterials is presented. Specific coding sequences result in various THz far‐field reflection and scattering patterns, ranging from a single beam to two, three, and numerous beams, which depart obviously from the ordinary Snell's law of reflection. By optimizing the coding sequences, a wideband THz thin film metamaterial with extremely low specular reflection, due to the scattering of the incident wave into various directions, is demonstrated. As a result, the reflection from a flat and flexible metamaterial can be nearly uniformly distributed in the half space with small intensity at each specific direction, manifesting a diffuse reflection from a rough surface. Both simulation and experimental results show that a reflectivity less than −10 dB is achieved over a wide frequency range from 0.8 to 1.4 THz, and it is insensitive to the polarization of the incident wave. This work reveals new opportunities arising from coding metamaterials in effective manipulation of THz wave propagation and may offer widespread applications.
The manipulation of terahertz (THz) waves is implemented by 1‐bit THz coding metamaterials. The reflection and scattering wave can be controlled by varying the coding sequence. Using this methodology, a wideband and polarization‐independent THz thin‐film metamaterial with extremely low specular reflection and scattering waves is demonstrated successfully. This metamaterial is also flexible and conformal to the curved surface, which offers widespread applications.
Circular RNAs (circRNAs) are increasingly gaining importance and attention due to their diverse potential functions and their value as diagnostic biomarkers (disease specific). This study aims to ...explore the novel mechanisms by which exosome-contained circRNAs promote tumor development and metastasis in TNBC. We identified increased circRNA circPSMA1 in TNBC cells, their exosomes, and serum exosomes samples from TNBC patients. The overexpression of circPSMA1 promoted TNBC cell proliferation, migration, and metastasis both in vitro and in vivo. Moreover, we investigated the tumor-infiltrating immune cells (TICs) or stromal components in immune microenvironment (IME), and identified the significant differences in the immune cells between TNBC and non-TNBC samples. Mechanistically, circPSMA1 acted as a "miRNAs sponge" to absorb miR-637; miR-637 inhibited TNBC cell migration and metastasis by directly targeted Akt1, which recognized as a key immune-related gene and affected downstream genes β-catenin and cyclin D1. Subsequent co-culture experiments also demonstrated that exosomes from TNBC carrying large amounts of circPSMA1 could transmit migration and proliferation capacity to recipient cells. Kaplan-Meier plots showed that high expression of Akt1 and low expression of mir-637 are highly correlated with poor prognosis in patients with lymph node metastasis of TNBC. Collectively, all these results reveal that circPSMA1 functions as a tumor promoter through the circPSMA1/miR-637/Akt1-β-catenin (cyclin D1) regulatory axis, which can facilitate the tumorigenesis, metastasis, and immunosuppression of TNBC. Our research proposes a fresh perspective on novel potential biomarkers and immune treatment strategies for TNBC.
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