Abstract
Tuning metal–support interaction has been considered as an effective approach to modulate the electronic structure and catalytic activity of supported metal catalysts. At the atomic level, ...the understanding of the structure–activity relationship still remains obscure in heterogeneous catalysis, such as the conversion of water (alkaline) or hydronium ions (acid) to hydrogen (hydrogen evolution reaction, HER). Here, we reveal that the fine control over the oxidation states of single-atom Pt catalysts through electronic metal–support interaction significantly modulates the catalytic activities in either acidic or alkaline HER. Combined with detailed spectroscopic and electrochemical characterizations, the structure–activity relationship is established by correlating the acidic/alkaline HER activity with the average oxidation state of single-atom Pt and the Pt–H/Pt–OH interaction. This study sheds light on the atomic-level mechanistic understanding of acidic and alkaline HER, and further provides guidelines for the rational design of high-performance single-atom catalysts.
Extracellular vesicles (EVs), a class of heterogeneous membrane vesicles, are generally divided into exosomes and microvesicles on basis of their origination from the endosomal membrane or the plasma ...membrane, respectively. EV-mediated bidirectional communication among various cell types supports cancer cell growth and metastasis. EVs derived from different cell types and status have been shown to have distinct RNA profiles, comprising messenger RNAs and non-coding RNAs (ncRNAs). Recently, ncRNAs have attracted great interests in the field of EV-RNA research, and growing numbers of ncRNAs ranging from microRNAs to long ncRNAs have been investigated to reveal their specific functions and underlying mechanisms in the tumor microenvironment and premetastatic niches. Emerging evidence has indicated that EV-RNAs are essential functional cargoes in modulating hallmarks of cancers and in reciprocal crosstalk within tumor cells and between tumor and stromal cells over short and long distance, thereby regulating the initiation, development and progression of cancers. In this review, we discuss current findings regarding EV biogenesis, release and interaction with target cells as well as EV-RNA sorting, and highlight biological roles and molecular mechanisms of EV-ncRNAs in cancer biology.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Flexible thermoelectrics is a synergy of flexible electronics and thermoelectric energy conversion. To date, state-of-the-art thermoelectrics is based on inorganic semiconductors that afford high ...electron mobility but lack in mechanical flexibility. By contrast, organic materials are amply flexible but low in electrical mobility and power output; the inorganic-organic hybrid design is a viable material-level option but has critical device-level issues for practical application. Here, we reported high intrinsic flexibility and state-of-the-art figures of merit (up to 0.44 at 300 K and 0.63 at 450 K) in Ag
2
S-based inorganic materials, opening a new avenue of flexible thermoelectrics. In the flexible full-inorganic devices made of such Ag
2
S-based materials, high electrical mobility yielded a normalized maximum power density up to 0.08 W m
−1
under a temperature difference of 20 K near room temperature, orders of magnitude higher than organic devices and organic-inorganic hybrid devices. These results promised an emerging paradigm and market of wearable thermoelectrics.
Flexible thermoelectrics is a synergy of flexible electronics and thermoelectric energy conversion. In this work, we fabricated flexible full-inorganic thermoelectric power generation modules based on doped silver chalcogenides.
Inorganic–organic hybrid perovskites are a new family of solar cell materials, which have recently been used to make solar cells with efficiency approaching 20%. Here, we report the unique defect ...chemistry of the prototype material, CH3NH3PbI3, based on first-principles calculation. We found that both the Pb cations and I anions in this material exhibit strong covalency as characterized by the formation of Pb dimers and I trimers with strong covalent bonds at some of the intrinsic defects. The Pb dimers and I trimers are only stabilized in a particular charge state with significantly lowered energy, which leads to deep charge-state transition levels within the band gap, in contradiction to a recent proposal that this system has only shallow intrinsic defects. Our results show that, in order to prevent the deep-level defects from being effective recombination centers, the equilibrium carrier concentrations should be controlled so that the Fermi energy is about 0.3 eV away from the band edges. Beyond this range, according to a Shockley–Read–Hall analysis, the non-equilibrium carrier lifetime will be strongly affected by the concentration of I vacancies and the anti-site defects with I occupying a CH3NH3 site.
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IJS, KILJ, NUK, PNG, UL, UM
To investigate the effectiveness of a school-based program promoting outdoor activities in Taiwan for myopia prevention and to identify protective light intensities.
Multi-area, cluster-randomized ...intervention controlled trial.
A total 693 grade 1 schoolchildren in 16 schools participated. Two hundred sixty-seven schoolchildren were in the intervention group and 426 were in the control group.
Initially, 24 schools were randomized into the intervention and control groups, but 5 and 3 schools in the intervention and control groups, respectively, withdrew before enrollment. A school-based Recess Outside Classroom Trial was implemented in the intervention group, in which schoolchildren were encouraged to go outdoors for up to 11 hours weekly. Data collection included eye examinations, cycloplegic refraction, noncontact axial length measurements, light meter recorders, diary logs, and questionnaires.
Change in spherical equivalent and axial length after 1 year and the intensity and duration of outdoor light exposures.
The intervention group showed significantly less myopic shift and axial elongation compared with the control group (0.35 diopter D vs. 0.47 D; 0.28 vs. 0.33 mm; P = 0.002 and P = 0.003) and a 54% lower risk of rapid myopia progression (odds ratio, 0.46; 95% confidence interval CI, 0.28-0.77; P = 0.003). The myopic protective effects were significant in both nonmyopic and myopic children compared with controls. Regarding spending outdoor time of at least 11 hours weekly with exposure to 1000 lux or more of light, the intervention group had significantly more participants compared with the control group (49.79% vs. 22.73%; P < 0.001). Schoolchildren with longer outdoor time in school (≥200 minutes) showed significantly less myopic shift (measured by light meters; ≥1000 lux: 0.14 D; 95% CI, 0.02-0.27; P = 0.02; ≥3000 lux: 0.16 D; 95% CI, 0.002-0.32; P = 0.048).
The school-based outdoor promotion program effectively reduced the myopia change in both nonmyopic and myopic children. Outdoor activities with strong sunlight exposure may not be necessary for myopia prevention. Relatively lower outdoor light intensity activity with longer time outdoors, such as in hallways or under trees, also can be considered.
Grain size is an important component trait of grain yield, which is frequently threatened by abiotic stress. However, little is known about how grain yield and abiotic stress tolerance are regulated. ...Here, we characterize GSA1, a quantitative trait locus (QTL) regulating grain size and abiotic stress tolerance associated with metabolic flux redirection. GSA1 encodes a UDP-glucosyltransferase, which exhibits glucosyltransferase activity toward flavonoids and monolignols. GSA1 regulates grain size by modulating cell proliferation and expansion, which are regulated by flavonoid-mediated auxin levels and related gene expression. GSA1 is required for the redirection of metabolic flux from lignin biosynthesis to flavonoid biosynthesis under abiotic stress and the accumulation of flavonoid glycosides, which protect rice against abiotic stress. GSA1 overexpression results in larger grains and enhanced abiotic stress tolerance. Our findings provide insights into the regulation of grain size and abiotic stress tolerance associated with metabolic flux redirection and a potential means to improve crops.
As soluble catalysts, redox mediators can reduce the high charging overpotential of lithium-oxygen batteries by providing sufficient liquid-solid interface for lithium peroxide decomposition. ...However, the redox mediators usually introduce undesirable reactions. In particular, the so-called "shuttle effect" leads to the loss of both the redox mediators and electrical energy efficiency. In this study, an organic compound, triethylsulfonium iodide, is found to act bifunctionally as both a redox mediator and a solid electrolyte interphase-forming agent for lithium-oxygen batteries. During charging, the organic iodide exhibits comparable lithium peroxide-oxidizing capability with inorganic iodides. Meanwhile, it in situ generates an interfacial layer on lithium anode via reductive ethyl detaching and the subsequent oxidation. This layer prevents the lithium anode from reacting with the redox mediators and allows efficient lithium-ion transfer leading to dendrite-free lithium anode. Significantly improved cycling performance has been achieved by the bifunctional organic iodide redox mediator.
Thermoelectric (TE) power generation is expected to be one of the most effective solutions to convert industrial exhaust heat to electricity for conserving fossil energy and reducing carbon ...emissions. However, its real application is obstructed decisively by the weakness of the service stability of state‐of‐the‐art TE materials at high temperatures in air. Refractory iron silicide (β‐FeSi2) used to be widely investigated as TE materials, but the low zT has restricted its practical application and even made it almost vanish from TE research in recent years. Here, guided by theoretical calculation, ultrahigh solubility of Ir on the Fe sites of β‐FeSi2 is successfully realized. Doping 16% Ir elicits multi‐valley electrical conduction and phonon‐electron scattering, doubling the previous zT record of β‐FeSi2 to ≈0.6 at 1000 K. The TE properties of the obtained β‐FeSi2 are practically unchanged after thermal aging in air at 1173 K. The new conceptual electrode‐less β‐FeSi2‐based refractory module demonstrates considerable power density and stable power generation when it is burned by a gas flame in air. These results mark a step toward developing practical TE power generation technology for the recovery of industrial waste heat.
Guided by theoretical calculation, ultrahigh solubility of Ir on the Fe sites of β‐FeSi2 is realized. Doping 16% Ir elicits multi‐valley electrical conduction and phonon‐electron scattering, doubling the previous zT record of refractory β‐FeSi2 to ≈0.6 at 1000 K. The new conceptual electrode‐less β‐FeSi2‐based refractory module demonstrates stable power generation when it is burned by a gas flame in air.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The belief that the vertebrate brain functions normally without classical lymphatic drainage vessels has been held for many decades. On the contrary, new findings show that functional lymphatic ...drainage does exist in the brain. The brain lymphatic drainage system is composed of basement membrane-based perivascular pathway, a brain-wide glymphatic pathway, and cerebrospinal fluid (CSF) drainage routes including sinus-associated meningeal lymphatic vessels and olfactory/cervical lymphatic routes. The brain lymphatic systems function physiological as a route of drainage for interstitial fluid (ISF) from brain parenchyma to nearby lymph nodes. Brain lymphatic drainage helps maintain water and ion balance of the ISF, waste clearance, and reabsorption of macromolecular solutes. A second physiological function includes communication with the immune system modulating immune surveillance and responses of the brain. These physiological functions are influenced by aging, genetic phenotypes, sleep-wake cycle, and body posture. The impairment and dysfunction of the brain lymphatic system has crucial roles in age-related changes of brain function and the pathogenesis of neurovascular, neurodegenerative, and neuroinflammatory diseases, as well as brain injury and tumors. In this review, we summarize the key component elements (regions, cells, and water transporters) of the brain lymphatic system and their regulators as potential therapeutic targets in the treatment of neurologic diseases and their resulting complications. Finally, we highlight the clinical importance of ependymal route-based targeted gene therapy and intranasal drug administration in the brain by taking advantage of the unique role played by brain lymphatic pathways in the regulation of CSF flow and ISF/CSF exchange.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Sporadic E (Es) layers are known for their layered structures with enhanced electron density. Recently, some scientists have studied the relationship between the occurrence rate and intensity of the ...Es layer in the global distribution. However, the relationship between the Es layer parameters (Es layer occurrence rate, Es layer intensity, Es layer thickness) in the vertical direction seems to be ignored to date. This paper highlights the vertical profiles of the occurrence rate, intensity, and thickness of the Es layers by using scintillation index (S4) from FORMOSAT‐3/COSMIC satellites from July 2007 to March 2015. The results show that there are some persistent differences between the occurrence rate, intensity, and thickness of the Es layers in the vertical profiles, which is different from their general similarity in the latitude distribution. It is found that the Es layer occurrence rate has a maximum value at ∼102 km altitude, but the Es layer intensity and Es layer thickness reach their maximum at an altitude of ∼110 km. Besides, the intensity and thickness of the Es layer exhibit a high linear relationship, which suggests that the larger electron density of the Es layer, the thicker its thickness. The Horizontal Wind Model (HWM14) indicates that the latitudinal variations in Es layers parameters are highly coincident with the zonal wind shear. However, the altitudinal variations in Es layers parameters do not agree well with the zonal wind shear.
Key Points
The vertical variations of the occurrence rate, intensity, and thickness of the Sporadic E (Es) layers are presented in detail
Their vertical variations exist obvious discrepancies, which is different from their high similarity in latitude
Compared with the Es layer occurrence rate, the Es layer intensity can better reflect the evolution of the Es layer in vertical direction
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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