Sudden impulses (SIs) are an important source of ultra low frequency (ULF) wave activity throughout the Earth's magnetosphere. Most SI‐induced ULF wave events have been reported in the dayside ...magnetosphere; it is not clear when and how SIs drive ULF wave activity in the nightside plasma sheet. We examined the ULF response of the nightside plasma sheet to SIs using an ensemble of 13 SI events observed by THEMIS (Timed History of Events and Macroscale Interactions during Substorms) satellites (probes). Only three of these events resulted in ULF wave activity. The periods of the waves are found to be 3.3, 6.0, and 7.6 min. East‐west magnetic and radial electric field perturbations, which typically indicate the toroidal mode, are found to be stronger and can have phase relationships consistent with standing waves. Our results suggest that the two largest‐amplitude ULF responses to SIs in the nightside plasma sheet are tailward‐moving vortices, which have previously been reported, and the dynamic response of cross‐tail currents in the magnetotail to maintain force balance with the solar wind, which has not previously been reported as a ULF wave driver. Both mechanisms could potentially drive standing Alfvén waves (toroidal modes) observed via the field‐line resonance mechanism. Furthermore, both involve frequency selection and a preference for certain driving conditions that can explain the small number of ULF wave events associated with SIs in the nightside plasma sheet.
Key Points
In 3 of 13 SI events, steady ULF wave is induced in the nightside plasma sheet
Field perturbations are usually consistent with standing toroidal Alfven waves
Tailward moving vortices or dynamic response of tail currents may explain
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•Nanosecond laser irradiation produces either copper or oxygen vacancies depending on the atmosphere during the process.•The generation of copper vacancies can be confirmed by XPS and ...Raman spectroscopy.•Oxygen vacancies improves the performance of CuO nanowires for glucose sensing while copper vacancies deteriorate it.
Defect engineering in CuO nanomaterials has been extensively investigated because this technology can greatly improve the performance of CuO components in a variety of applications. While many previous studies have focused on the role of oxygen vacancies, (VO), in CuO, little attention has been paid to that of copper vacancy centers, (VCu), since the presence of these defects is often difficult to quantify. As a result, the specific roles played by these different vacancy centers on the measured properties of CuO have not been studied systematically. In this article, we show that the concentration of both VO and VCu centers can be engineered in CuO NWs through nanosecond (ns) laser irradiation. The identification of these vacancies was achieved through X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Absorption spectra and diffuse reflectance spectra of laser-processed samples show that increasing the concentration of VO centers enhances the optical absorption of CuO in the visible region. Data obtained from Mott-Schottky and Nyquist plots, together with measured I-V characteristics, show that laser-induced VCu centers can enhance the carrier concentration in CuO NWs. These data, in addition to O 1s XPS spectra on laser-processed and unprocessed samples as well as cyclic voltammetry, also indicate that laser irradiation can significantly enhance surface adsorption for applications in photo-electrochemistry and electrochemistry. To demonstrate the efficacy of this laser irradiation technique for potential electrochemistry applications, the role of laser-induced VCu and VO defect centers in CuO NWs on the non-enzymatic sensing of glucose has also been investigated. We find that the introduction of VO centers in CuO NWs enhances the current response for glucose sensing while the presence of VCu centers inhibits this response.
The exploration of the utilization of sustainable, green energy represents one way in which it is possible to ameliorate the growing threat of the global environmental issues and the crisis in ...energy. Moisture, which is ubiquitous on Earth, contains a vast reservoir of low‐grade energy in the form of gaseous water molecules and water droplets. It has now been found that a number of functionalized materials can generate electricity directly from their interaction with moisture. This suggests that electrical energy can be harvested from atmospheric moisture and enables the creation of a new range of self‐powered devices. Herein, the basic mechanisms of moisture‐induced electricity generation are discussed, the recent advances in materials (including carbon nanoparticles, graphene materials, metal oxide nanomaterials, biofibers, and polymers) for harvesting electrical energy from moisture are summarized, and some strategies for improving energy conversion efficiency and output power in these devices are provided. The potential applications of moisture electrical generators in self‐powered electronics, healthcare, security, information storage, artificial intelligence, and Internet‐of‐things are also discussed. Some remaining challenges are also considered, together with a number of suggestions for potential new developments of this emerging technology.
Moisture exists everywhere on Earth and it contains a tremendous amount of energy that remains unexploited. The recent progress in moisture‐enabled electricity generation in terms of the physics, materials, structures, and potential self‐powered applications in healthcare, security, information storage, and artificial intelligence is explored.
Amino acids play a key role in regulating milk protein synthesis partly through activation of the mammalian target of rapamycin (mTOR) signaling pathway. However, the involvement of extracellular AA ...sensing receptors in this process is not well understood. In nonruminants, it is well established that the AA taste 1 receptor member 1/3 (TAS1R1/TAS1R3) heterodimer contributes to the sensing of most l-AA. Whether this receptor is functional in bovine mammary cells is unknown. The objective of this study was to determine essential AA signaling through TAS1R1/TAS1R3 and their roles in regulating mTOR signaling pathway and casein mRNA abundance in primary bovine mammary epithelial cells and the Mac-T cell line. The bovine mammary epithelial cells were stimulated with complete Dulbecco's modified Eagle's medium (+EAA), medium without EAA (−EAA), or medium supplemented with only 1 of the 10 essential AA, respectively. The nonessential AA levels were the same across all treatments. Small interference RNA targeting TAS1R1 were designed and transfected into bovine primary mammary epithelial cells (bPMEC). Supplementation of a complete mixture of essential AA or Arg, Val, Leu, His, Phe, Met, and Ile individually led to greater mTOR phosphorylation. Phosphorylation of ribosomal protein S6 kinase β-1 was greater in the presence of Val, Leu, Trp, Met, and Ile. Valine, Leu, Met, and Ile led to greater eIF4E-binding protein 1 phosphorylation. Although +EAA and a few individual AA tested induced increases in intracellular calcium, Met and Val were the most potent. Knockdown of TAS1R1 decreased intracellular calcium in bPMEC cultured with both Val and Met. Phosphorylation of mTOR, ribosomal protein S6 kinase β-1, and eIF4E-binding protein 1 was lower when TAS1R1 was knocked-down in bPMEC supplemented with Val and Met. In addition, small interference RNA silencing of TAS1R1 resulted in lower β-casein (CSN2) abundance. The TAS1R1/TAS1R3 receptor may sense extracellular AA and activate mTOR signaling in bovine mammary cells, likely by elevating intracellular calcium concentration. This mechanism appears to have a role in Met- and Val-induced changes in CSN2 mRNA abundance. Further in vivo studies will have to be performed to assess the relevance of this mechanism in the mammary gland.
The information technologies have been increasing exponentially following Moore’s law over the past decades. This has fundamentally changed the ways of work and life. However, further improving data ...process efficiency is facing great challenges because of physical and architectural limitations. More powerful computational methodologies are crucial to fulfill the technology gap in the post-Moore’s law period. The memristor exhibits promising prospects in information storage, high-performance computing, and artificial intelligence. Since the memristor was theoretically predicted by L. O. Chua in 1971 and experimentally confirmed by HP Laboratories in 2008, it has attracted great attention from worldwide researchers. The intrinsic properties of memristors, such as simple structure, low power consumption, compatibility with the complementary metal oxide-semiconductor (CMOS) process, and dual functionalities of the data storage and computation, demonstrate great prospects in many applications. In this review, we cover the memristor-relevant computing technologies, from basic materials to in-memory computing and future prospects. First, the materials and mechanisms in the memristor are discussed. Then, we present the development of the memristor in the domains of the synapse simulating, in-memory logic computing, deep neural networks (DNNs) and spiking neural networks (SNNs). Finally, the existent technology challenges and outlook of the state-of-art applications are proposed.
Many researchers have reported that obesity is a major risk factor for diabetes, cardiovascular diseases, several forms of cancer (such as breast, colon and prostate), pulmonary, osteoarticular and ...metabolic diseases in the past decades. Recently, the hypolipidemic and anti-obesity effects of green tea in animals and humans have slowly become a hot topic in nutritional and food science research. This review will up-date the information of the anti-obesity effects of green tea in human intervention and animal studies. During recent years, an increasing number of clinical trials have confirmed the beneficial effects of green tea on obesity. However, the optimal dose has not yet been established owing to the very different results from studies with a similar design, which may be caused by differences in the extent of obesity, dietary intake, physical activity intensity, the strength of subjects' compliance to test instruction, the genetic background of populations, body composition and dietary habits. Therefore, further investigations on a larger scale and with longer periods of observation and tighter controls are needed to define optimal doses in subjects with varying degrees of metabolic risk factors and to determine differences in beneficial effects among diverse populations. Moreover, data from laboratory studies have shown that green tea has important roles in fat metabolism by reducing food intake, interrupting lipid emulsification and absorption, suppressing adipogenesis and lipid synthesis and increasing energy expenditure via thermogenesis, fat oxidation and fecal lipid excretion. However, the exact molecular mechanisms remain elusive.
The effects of finite particle size on electrostatics, density profiles, and diffusion have been a long existing topic in the study of ionic solution. The previous size-modified Poisson-Boltzmann and ...Poisson-Nernst-Planck models are revisited in this article. In contrast to many previous works that can only treat particle species with a single uniform size or two sizes, we generalize the Borukhov model to obtain a size-modified Poisson-Nernst-Planck (SMPNP) model that is able to treat nonuniform particle sizes. The numerical tractability of the model is demonstrated as well. The main contributions of this study are as follows. 1), We show that an (arbitrarily) size-modified PB model is indeed implied by the SMPNP equations under certain boundary/interface conditions, and can be reproduced through numerical solutions of the SMPNP. 2), The size effects in the SMPNP effectively reduce the densities of highly concentrated counterions around the biomolecule. 3), The SMPNP is applied to the diffusion-reaction process for the first time, to our knowledge. In the case of low substrate density near the enzyme reactive site, it is observed that the rate coefficients predicted by SMPNP model are considerably larger than those by the PNP model, suggesting both ions and substrates are subject to finite size effects. 4), An accurate finite element method and a convergent Gummel iteration are developed for the numerical solution of the completely coupled nonlinear system of SMPNP equations.
This study examines the persistent impacts of historical racebased discriminatory housing policies on contemporary urban environments in the United States. Specifically, we examine the relationships ...between Home Owners' Loan Corporation (HOLC) grades assigned to neighborhoods in the 1930s and the current distribution of tree canopy and level of exposure to air pollution hazards. Our results indicate a clear gradient in tree canopy by HOLC grade, with better neighborhood grades associated with significantly higher percentage of tree canopy coverage. The pattern also exists for airborne carcinogens and respiratory hazards, with worse neighborhood grades associated with significantly higher hazards exposure. Our findings indicate that early 20th century discriminatory housing policies exert a contemporary influence on patterns of green space exposure in American cities, with implications for health and health inequities. Our findings suggest that, in order to achieve equitable access to the benefits of urban greenspace, we must acknowledge these historical influences and consider policies and practices that directly counter these influences, for example, through targeted greenspace development in areas historically identified as unfit for investment.
•Increasing urban tree canopy is a recognized strategy to reduce air pollutants.•There is a systematic disparity in spatial distributions of urban tree canopy.•Current levels of tree canopy reflect a gradient established by the HOLC maps.•There is a similar gradient in airborne carcinogens and respiratory hazards.
1,4,5,8-Naphthalenetetracarboxylic dianhydride (NTCDA)-derived Polyimide is proposed as the anode material for aqueous rechargeable lithium-ion or sodium-ion battery (ARLB or ARSB), which is based on ...a mechanism beyond the intercalation chemistry. Comparing with other transient oxide anode for ARLB, Polyimide has more suitable working voltage, higher capacity and better structure stability. Therefore, the ARLB with Polyimide anode and LiCoO2 cathode presents a specific capacity of 71 mAh g-1 and a specific energy of 80 Wh kg-1 in 5 M LiNO3 solution at the current rate of 100 mA g-1, which is the highest among all reported ARLB system. Besides, it shows excellent cycling stability and rate capability. The ARSB system is demonstrated by Polyimide/NaVPO4F cell. It has been proved that the Polyimide anode has a good capacity performance and cycling stability in 5 M NaNO3 solution. The two aqueous rechargeable batteries with Polyimide anode both show a promising prospect in large-scale energy storage.
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