Sustainable All-Day Thermoelectric Power Generation From the Hot Sun and Cold Universe.

Energy conversion from the environment into electricity is the most direct and effective electricity source to sustainably power off-grid electronics, once the electricity requirement exceeds the capability of traditional centralized power supply systems. Normally photovoltaic cells have enabled distributed power generation during the day, but do not work at night. Thus, efficient electricity generation technologies for a sustainable all-day power supply with no necessity for energy storage remain a challenge. Herein, an innovative all-day power generation strategy is reported, which self-adaptively integrates the diurnal photothermal and nocturnal radiative cooling processes into the thermoelectric generator (TEG) via the spectrally dynamic modulated coating, to continuously harvest the energy from the hot sun and the cold universe for power generation. Synergistic with the optimized latent heat phase change material, the electricity generation performance of the TEG is dramatically enhanced, with a maximum power density exceeding 1000 mW m-2 during the daytime and up to 25 mW m-2 during the nighttime, corresponding to an improvement of 123.1% and 249.1%, compared with the conventional strategy. This work maximizes the utilization of ambient energy resources to provide an environmentally friendly and uninterrupted power generation strategy. This opens up new possibilities for sustained power generation both daytime and nighttime.

Understanding the Activity Trends in Electrocatalytic Nitrate Reduction to Ammonia on Cu Catalysts.

Cu-based catalysts possess great potential in the electrocatalytic nitrate (NO3-) reduction reaction for ammonia (NH3) synthesis. However, the low atomic economy limits their further application. Here we report a Cu single-atom (SA) incorporated in nitrogen-doped carbon (Cu SA/NC) with high atomic economy, which exhibits superior NH3 Faradaic efficiency (FE) of 100% along with an impressive NH3 yield rate of 7480 µg h-1 mgcat.-1. As counterparts, Cus+n/NC, with mixed SA and nanoparticles (NPs), shows decreasing NH3 FE with decreasing SA content, but the production of N2 and N2O increases gradually, which reaches the maximum on pure Cu NPs. In situ characterizations and theoretical calculations reveal that a higher NH3 FE of Cu SA/NC is ascribed to a lower free energy of the rate-limiting step (HNO* → N*) and effective inhibition for the N-N coupled process. This work provides the intuitive activity trends of Cu-based catalysts, opening an avenue for subsequent catalysts design.

Highly Solvent Resistant Small-Molecule Hole-Transporting Materials for Efficient Perovskite Quantum Dot Light-Emitting Diodes.

Perovskite quantum dot light-emitting diodes (Pe-QLEDs) have been shown as promising candidates for next-generation displays and lightings due to their unique feature of wide color gamut and high color saturation. Hole-transporting materials (HTMs) play crucial roles in the device performance and stability of Pe-QLEDs. However, small-molecule HTMs have been less studied in Pe-QLEDs due to their poor solvent resistance and low hole mobility. In this work, three novel small-molecule HTMs employing benzimidazole as the center core, named X4, X5, and X6, were designed and synthesized for application in Pe-QLEDs. One of the tailored HTM-X6 exhibits excellent solvent resistant ability to the perovskite quantum dot (QD) inks due to its proper solubility and low surface energy. Our result clearly demonstrated that the synergistic effect of poor solubility and low surface energy facilitates the achievement of good solvent resistance to perovskite QD inks. As a result, a promising maximal external quantum efficiency (EQE) of 14.1% is achieved in X6-based CsPbBr3 Pe-QLEDs, which is much higher than that of X4 (9.16%) and X5 (6.60%)-based devices, which is comparable to the PTAA reference (EQE ∼ 15.8%) under the same conditions. To the best of our knowledge, this is the first example that a benzimidazole-based small-molecule HTM demonstrated a good application in Pe-QLEDs. Our work provides new guidance for the rational design of small-molecule HTMs with high solvent resistance for efficient Pe-QLEDs and other photoelectronic devices.

Continuous Photothermal and Radiative Cooling Energy Harvesting by VO2 Smart Coatings with Switchable Broadband Infrared Emission.

Extensive use of renewable and clean energy is one of the promising ways to solve energy/environmental problems and promote the sustainable development of our society. As inexhaustible energy sources, the photothermal (PT) and radiative cooling (RC) energy from the sun and outer space have recently attracted tremendous interest. However, these two kinds of energy utilization have distinctly opposite spectral properties, especially in the infrared range, making it extremely difficult to integrate these two energy harvesting modes within a fixed device for continuous energy collection. Thus, in the current study, we have proposed a spectrally self-adaptive broadband absorber/emitter (SSBA/E) based on vanadium dioxide (VO2), a typical phase transition material, to achieve continuous energy harvesting via collecting solar thermal energy in PT mode during the day and obtaining cool energy in wide-band RC mode at night. Experimental results show that owing to the phase transition property of the VO2 layer, these two energy collection modes can be adaptively switched. Specifically, the VO2-based device shows a broadband infrared emissivity modulation from 0.21 to 0.75 and low critical temperatures (58.4 and 49.2 °C) during the phase transition, leading to continuous energy harvesting with high efficiency. Due to the broadband infrared emission, the RC maximum power of the SSBA/E device was estimated to be 58 W m-2. The proposed VO2 smart coatings are also applicable for many other applications such as thermal management of spacecraft, infrared camouflage, or adaptive optical devices.

The Extent of Platinum-Induced Hydrogen Spillover on Cerium Dioxide.

Hydrogen spillover from metal nanoparticles to oxides is an essential process in hydrogenation catalysis and other applications such as hydrogen storage. It is important to understand how far this process is reaching over the surface of the oxide. Here, we present a combination of advanced sample fabrication of a model system and in situ X-ray photoelectron spectroscopy to disentangle local and far-reaching effects of hydrogen spillover in a platinum-ceria catalyst. At low temperatures (25-100 °C and 1 mbar H2) surface O-H formed by hydrogen spillover on the whole ceria surface extending microns away from the platinum, leading to a reduction of Ce4+ to Ce3+. This process and structures were strongly temperature dependent. At temperatures above 150 °C (at 1 mbar H2), O-H partially disappeared from the surface due to its decreasing thermodynamic stability. This resulted in a ceria reoxidation. Higher hydrogen pressures are likely to shift these transition temperatures upward due to the increasing chemical potential. The findings reveal that on a catalyst containing a structure capable to promote spillover, hydrogen can affect the whole catalyst surface and be involved in catalysis and restructuring.

Perovskite QLED with an external quantum efficiency of over 21% by modulating electronic transport.

Perovskite quantum-dot-based light-emitting diodes (QLEDs) are highly promising for future solid-state lightings and high-definition displays due to their excellent color purity. However, their device performance is easily affected by charge accumulation induced luminescence quenching due to imbalanced charge injection in the devices. Here we report green perovskite QLEDs with simultaneously improved efficiency and operational lifetime through balancing the charge injection with the employment of a bilayered electron transport structure. The charge-balanced QLEDs exhibit a color-saturated green emission with a full-width at half-maximum (FWHM) of 18 nm and a peak at 520 nm, a low turn-on voltage of 2.0 V and a champion external quantum efficiency (EQE) of 21.63%, representing one of the most efficient perovskite QLEDs so far. In addition, the devices with modulated charge balance demonstrate a nearly 20-fold improvement in the operational lifetime compared to the control device. Our results demonstrate the great potential of further improving the device performance of perovskite QLEDs toward practical applications in lightings and displays via rational device engineering.

Extraordinary Deactivation Offset Effect of Arsenic and Calcium on CeO2-WO3 SCR Catalysts.

An extraordinary deactivation offset effect of calcium and arsenic on CeO2-WO3 catalyst had been found for selective catalytic reduction of NO with NH3 (NH3-SCR). It was discovered that the maximum NO x conversion of As-Ca poisoned catalyst reached up to 89% at 350 °C with the gaseous hourly space velocity of 120 000 mL·(g·h)-1. The offset effect mechanisms were explored with respect to the changes of catalyst structure, surface acidity, redox property and reaction route by XRD, XPS, H2-TPR, O2-TPD, NH3-TPD and in situ Raman, in situ TG, and DRIFTS. The results manifested that Lewis acid sites and reducibility originating from CeO2 were obviously recovered, because the strong interaction between cerium and arsenic was weakened when Ca and As coexisted. Meanwhile, the CaWO4 phase generated on Ca poisoned catalyst almost disappeared after As doping together, which made for Brønsted acid sites reformation on catalyst surface. Furthermore, surface Ce4+ proportion and oxygen defect sites amount were also restored for two-component poisoned catalyst, which favored NH3 activation and further reaction. Finally, the reasons for the gap of catalytic performance between fresh and As-Ca poisoned catalyst were also proposed as follows: (1) surface area decrease; (2) crystalline WO3 particles generation; and (3) oxygen defect sites irreversible loss.

Dechlorination of chlorobenzene on vanadium-based catalysts for low-temperature SCR.

Chlorobenzene (CB) inhibits SCR activity of V-based catalysts at low temperature, though the adsorption amount is small. NH3 adsorption increases due to the break in the C-Cl bond during CB oxidation. The dissociated Cl- ions provide extra Brønsted acid sites, leading to the formation of inactive NH4Cl. Ce and Mn improve dechlorination, forming more NH4Cl on the catalyst surface.

A new secondary metabolite from the fermented mycelia of Streptomyces antibiotic H41-55.

An actinomycete strain, H41-55 from sea sediment was identified as Streptomyces antibiotic on the basis of its morphological, physiological and biochemical characteristics as well as 16S rDNA data. A new secondary metabolite, (2S,3R)-N-[3-(formylamino)-2-hydroxybenzoyl]-l-threonine propyl ester (1), together with five known compounds was isolated from fermentation product by use of silica gel and Sephadex LH-20 column chromatography, and preparative RP-C18 HPLC, and identified by HR-TOF-MS and NMR spectra. The cytotoxicities of these isolates against three cancer cell lines and their antifungal activities on Candida albicans were tested. Compounds 1, 3, 5, and 6 displayed moderate cytotoxicity. 5 and 6 showed inhibitory activity on C. albicans.

Identification of the arsenic resistance on MoO3 doped CeO2/TiO2 catalyst for selective catalytic reduction of NOx with ammonia.

Arsenic resistance on MoO3 doped CeO2/TiO2 catalysts for selective catalytic reduction of NOx with NH3 (NH3-SCR) is investigated. It is found that the activity loss of CeO2-MoO3/TiO2 caused by As oxide is obvious less than that of CeO2/TiO2 catalysts. The fresh and poisoned catalysts are compared and analyzed using XRD, Raman, XPS, H2-TPR and in situ DRIFTS. The results manifest that the introduction of arsenic oxide to CeO2/TiO2 catalyst not only weakens BET surface area, surface acid sites and adsorbed NOx species, but also destroy the redox circle of Ce(4+) to Ce(3+) because of interaction between Ce and As. When MoO3 is added into CeO2/TiO2 system, the main SCR reaction path are found to be changed from the reaction between coordinated NH3 and ad-NOx species to that between an amide and gaseous NO. Additionally, for CeO2-MoO3/TiO2 catalyst, As toxic effect on active sites CeO2 can be released because of stronger As-Mo interaction. Moreover, not only are the reactable Brønsted and Lewis acid sites partly restored, but the cycle of Ce(4+) to Ce(3+) can also be free to some extent.

[Research on ground scenery spectral radiation source with tunable spectra].

A spectrum-tunable ground scenery spectrum radiation source, using LEDs and bromine tungsten lamp as luminescence media, was introduced. System structure and control of the spectrum radiation source was expounded in detail. In order to simulate various ground scenery spectrum distribution with different shapes, a ground scenery spectral database was established in the control system. An improved genetic algorithm was proposed, and a large number of ground scenery spectra were produced by the simulator. Spectral similarity and the average spectral matching error of several typical ground scenery spectra were further analyzed. Spectral similarity of red bands, green bands, blue bands and near-infrared spectral band also was discussed. When the radiance of the target was 50 W x (m2 x sr)(-1), the average spectral matching error was less than 10% and spectral similarity was greater than 0.9, up to 0.983. Spectral similarity of red band, green band, blue band and near-infrared band (especially green band and near-infrared band) was less than that of full-band. Compared with blue band and red band, spectral similarity of green band and near-infrared band low-amplitude maximum can rearch 50%. Ground scenery spectrum radiation source can be used as radiometric calibration source for optical remote sensor, and calibration error, which is caused by objectives and calibration sources spectral mismatch, can be effectively reduced.

Equalization of loudspeaker response using balanced model truncation.

Traditional loudspeaker equalization algorithms cannot decide the order of an equalizer before the whole equalization procedure has been completed. Designers have to try many times before they determine a proper order of the equalization filter. A method which solves this drawback is presented for loudspeaker equalization using balanced model truncation. The order of the equalizer can be easily decided using this algorithm and the error between the model and the loudspeaker can also be readily controlled. Examples are presented and the performance of the proposed method is discussed with comparative experiments.

[Effectiveness and safety of acupuncture for supraventricular tachycardia: a systematic review and meta-analysis].

The effectiveness and safety of acupuncture for the treatment of supraventricular tachycardia were systematically reviewed. The randomized controlled trials (RCTs) regarding acupuncture for supraventricular tachycardia were searched in domestic and overseas databases, and the evaluation tool of bias risk in Cochrane Handbook 5.1.0 software was used to perform the evaluation of bias risk in literature, and RevMan 5.2 software was applied for statistics and Meta-analysis. Five RCTs involving 323 patients were included. The results showed that compared with the blank control group, the acupuncture reduced the heart rate by 18.8 times/min [95% CI (12.68, 24.92)]; the clinical effective rate in the acupuncture group was superior to that in the diltiazem group [OR= 3.11, 95% CI (1.50, 6.46)]; the difference of immediate effect between propafenone and acupuncture was not significant. No reports regarding adverse events was described in 5 RCTs. As was shown in the present evidence, acupuncture is safe and effective for the treatment of supraventricular tachycardia, but the level of evidence was low and the intensity of conclusion needed to be improved.

[Spectral calibration for the large aperture infrared radiometer].

The present paper introduced a spectral calibration method to calibrate a large aperture infrared radiation facility. We developed a radiometer which consisted of optical system, infrared detectors(cavity pyroelectric detector and HgCdTe detector 2 - 14 microm), fine mechanical modulator, lock in amplifier, signal processor, etc. At first, we analyzed the method on how to measure the spectral calibration of the large aperture infrared radiometer, and established the spectral calibration facility. Then, we tested the nonlinear response for the cavity pyroelectric detector and HgCdTe detector. Finally, we used the cavity pyroelectric detector to calibrate the relative spectral responsivity of HgCdTe detector at several wavelengths on the facility. Through the comparison of the two methods for measuring the relative spectral responsivity, the average of multiple measurements and comparative analysis of two methods were given. The uncertainty analysis of the whole system showed that the measurement uncertainty of the facility was better than 3.4%.