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Stable picosecond dissipative soliton pulses were observed in an ytterbium-doped fiber laser employing a high-quality mixture of BP/SnSe2-PVA saturable absorber (SA). The modulation depth, saturation intensity, and non-saturable loss of the mixture of BP/SnSe2-PVA SA were measured with values of 5.98%, 18.37 MW/cm2, and 33%, respectively. Within the pump power range of 150–270 mW, stable dissipative soliton pulses were obtained with an output power of 1.68–4 mW. When the minimum pulse duration is 1.28 ps, a repetition rate of 0.903 MHz, center wavelength of 1064.38 nm and 3 dB bandwidth of 2 nm were obtained. The maximum pulse energy of 4.43 nJ and the signal-to-noise ratio up to 72 dB were achieved at pump power of 270 mW. The results suggest that the BP/SnSe2-PVA mixture SA has outstanding nonlinear saturable absorption characteristics and broad ultrafast laser applications. [ABSTRACT FROM AUTHOR]

A transition‐metal and ligand free base‐mediated a radical condensation reaction to form N‐substituted pyrrolyl ketones with water as the side product is developed. The transformation is performed with t‐BuOK, and a broad range of N‐substituted acetylpyrroles and alcohols are well tolerated under the optimized conditions. Preliminary studies indicate that the radical anion of the benzylic alcohol is proposed as the key intermediate, which undergoes coupling with the enolate of the acetylpyrrole to form the new CC bond. Subsequently, the corresponding pyrrolyl chalcones are obtained by elimination, and the enone intermediate is reduced to afford N‐substituted pyrrolyl ketones. The odor characteristics of the pyrrolyl ketones obtained were evaluated by gas‐chromatography–mass spectrometry–olfactometry (GC–MS–O). The pyrrolyl ketones present varied characteristic odors, which are usually distinct from those of the corresponding acetylpyrroles and alcohols. Among them, compounds of 3‐cyclopropyl‐1‐(1‐methyl‐1H‐pyrrol‐2‐yl) propan‐1‐one (3c′) and 5,9‐dimethyl‐1‐(1‐methyl‐1H‐pyrrol‐2‐yl) dec‐8‐en‐1‐one (3g′) were not decomposed under high temperature, according to the results of pyrolysis–GC/MS. [ABSTRACT FROM AUTHOR]

Purpose: Application of exogenous carbon (C) and nitrification inhibitors are common measures to regulate soil nitrogen cycling and mitigate greenhouse gas emissions. However, we lack knowledge on their direct effects on denitrification processes. Methods: A 15 N anaerobic microcosm experiment was conducted to investigate the effects of exogenous C and/or nitrification inhibitors on denitrification rate, N2O/(N2O + N2) product stoichiometry ratio, and nirS- and nirK-type denitrifiers in a calcareous soil. Exogenous C were wheat straw and wheat straw–derived biochar, and nitrification inhibitors were chemical nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) and biological nitrification inhibitor methyl 3-(4-hydroxyphenyl) propionate (MHPP). Results: Wheat straw, composite with much of liable C, significantly increased denitrification rate (3.96–4.19 times higher than control), N2O emission, and N2O/(N2O + N2) ratio (p < 0.05) by upregulating nirK and nirS genes of denitrifiers, and changing the community structure of nirS-type denitrifiers. By contrast, biochar, composite with much of recalcitrant organic C, increased the N2O/(N2O + N2) ratio but did not stimulate the denitrification rate (P > 0.05). One percent (w/w applied-N) DMPP, 1% MHPP, and 5% MHPP exhibited minor effects on denitrification rate, while 10% MHPP increased the denitrification rate by 1.32 times relative to control (p < 0.05). Wheat straw biochar applied with two nitrification inhibitors reshaped the community structure of nirK- and nirS-type denitrifiers, decreasing the denitrification rate compared with control, and the N2O/(N2O + N2) ratio compared with application of biochar alone (p < 0.05). Conclusions: The direct effects of exogenous C on denitrification and denitrification processes were dependent on the type of exogenous C applied. High dosage of MHPP (> 10% w/w) increased both denitrification rate and N2O/(N2O + N2) ratio. [ABSTRACT FROM AUTHOR]

Summary: Catalyst layer (CL) is the most important component in the high‐temperature proton exchange membrane fuel cell (HT‐PEMFC), as it offers reaction sites for hydrogen oxidation reaction (HOR) and oxygen reduction reactions (ORR). As the electrochemical reactions take place at gas/electron/proton interface, the length of this triple‐phase boundary (TPB) in the CL governs the rate of electrochemical reactions. As the TPB in the HT‐PEMFC has not been studied yet, a numerical non‐isothermal 3D model and a percolation micro model were developed in this work to investigate the effect of CLs' properties on both the TPB length and cell performance. The volume fractions, particle size, and particle size ratio of ionomer and Pt/C were selected for optimization. The results show that peak current density could be achieved at an ionomer volume fraction of 52%. Further improvement of cell performance requires smaller particle size and smaller particle size ratio of ionomer. Novelty statement: A three‐dimensional non‐isothermal model of HT‐PEMFC was developed. By adopting the percolation model, length of triple phase boundary of HT‐PEMFC was successfully quantified. The particle parameters including the particle size and ionomer volume fraction can be optimized to increase the length of triple phase boundary, thus achieving higher cell performance. [ABSTRACT FROM AUTHOR]

Rare-earth ion (RE3+) doped up-conversion (UC) fluorescent materials and novel fluorescent carbon quantum dots (CDs) have been widely used as traditional anti-counterfeiting materials owing to their excellent optical properties. The drawbacks of these materials are being exposed gradually with the widespread occurrence of counterfeit products in the market because of their single fluorescence mode and easy replication. In this work, we propose a novel strategy to combine both luminescent materials with different modes via a facile solvothermal method. Interesting, the composite materials show unalterable down-conversion (DC) blue light under a 365 nm ultraviolet (UV) analyzer, except for adjustable UC luminescence properties. The UC and DC optical properties are measured and the probable mechanism is proposed, indicating that the dual-mode fluorescence processes are separate and do not interference with each other. Moreover, we use a mixture containing a small number of UCMPs/CDs and poly(acrylic acid) (PAA) aqueous solution as a colorless anti-counterfeiting ink, and successfully print a variety of dual-mode fluorescence patterns through the screen printing technique, including QR codes, the logo of Wuhan University, and clover patterns. The composite materials show good dispersion and outstanding dual-mode fluorescence properties, suggesting that they are promising luminescent materials in the anti-counterfeiting field. [ABSTRACT FROM AUTHOR]

Achieving all‐printed, low‐cost, and large area electronic devices poses challenging requirements in employing printing technologies and conductive materials for flexible and wearable heaters. In this work, fully printed, scalable, and patterned flexible heaters based on Ag fractal dendrites (FDs) are fabricated through straightforward screen printing technology. The Ag FDs possess low sheet resistance with ≈0.83 Ω sq−1 when sintered at low temperature of 60 °C. The Ag FDs are directly printed on thin polyethylene terephthalate substrate to manufacture flexible heaters, exhibiting excellent heating performance with the saturation temperature up to ≈135 °C and rapid response time within 35 s under 4 V DC voltage. In addition, the Ag FDs heaters present lower power consumption (≈209.67 °C cm2 W−1), which is significantly better than traditional indium tin oxides (ITO) heaters (≈88 °C cm2 W−1). The sheet resistance of the devices remains stable after 2000 bending cycles with a radius of 10 mm, indicating that the outstanding mechanize stability of the heaters. Moreover, a large area (12 cm × 5 cm) heater with designable pattern is developed and attached to human body, indicating a bright future in next‐generation fully printed and wearable heating electronics application. Fully printed, scalable, and patterned flexible heaters based on Ag fractal dendrites are fabricated through straightforward screen printing technology, exhibiting excellent heating performance with the saturation temperature up to ≈135 °C and rapid response time within 35 s under 4 V DC voltage. [ABSTRACT FROM AUTHOR]

The broad applications of rechargeable batteries urge people to develop alternative energy storage devices with sustainable resources, high capacity, long cycling life, and wide-temperature operability. Aqueous proton batteries are considered as a state-of-the-art energy storage system due to their intrinsic safety and low cost. However, aqueous electrolytes have a low boiling point and narrow electrochemical stability window, limiting their applications in wide-temperature and high-energy batteries. Herein, a hybrid organic ionic liquid electrolyte with organic alkali 1-methyl-1,2,4-triazole (MTA) protonated by organic acid bis(trifluoromethysulfonyl)imide (HTFSI) as proton carriers and tetramethylene sulfone (TMS) as the solvent, noted as HTFSI-MTA-TMS, exhibited the stable electrochemical windows exceeding 5 V at -20 °C and 3.5 V at 80 °C. Benefiting from this electrolyte, the assembled MnO 2 -S//MoO 3 button proton full battery can display an operation voltage up to 1.8 V, energy density of 44.8 Wh kg -1 , and good cycling stability at room temperature when bis(trifluoromethanesulfonyl)imide manganese (II) salt (Mn(TFSI) 2 ) is introduced into the electrolyte, and run well in a wide-temperature range (-20 °C-60 °C). The work reveals the potential of organic acid-alkali coregulated electrolytes to meet the need of energy storage in a wide-temperature range and will advance the development of high-energy proton batteries., (© 2024 Wiley‐VCH GmbH.)