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Herein, the SrTiO 3 -TiO 2 -CaTiO 3 /Cu 2 O quaternary composite has been designed and prepared via one-step hydrothermal process followed by a NaBH 4 reduction treatment. By comparing the H 2 production rate (HPR) of Sr-Ti-Ca/Cu samples prepared by different Cu sources, it is found that Sr-Ti-Ca/Cu has the best H 2 production performance when CuCl 2 is as Cu source. As expected, the highest HPR of Sr-Ti-Ca/Cu sample is up to 5.088 mmol g−1 h−1, which is 195.7 times as higher as that of the Sr-Ti-Ca sample (0.026 mmol g−1 h−1) under the same conditions. Moreover, the HPR reached 0.692, 0.530 and 0.647 mmol g−1 h−1 in tap water, lake water and river water, indicating that the photocatalyst has high practicability in natural water sources. In addition, the experiment of the tap water composition effect on H 2 production performance shows that NO 3 − and SO 4 2− ions have great negative influence on the HPR. Compared with Sr-Ti-Ca, the light absorption of Sr-Ti-Ca/Cu extends over the entire visible region, the interface resistance decreases, and the photocurrent density increases. These results suggest that the well-designed dual p-n heterojunctions and dual type-II heterojunctions in Sr-Ti-Ca/Cu sample can enhance the light absorption in the ultraviolet region and realize the rapid separation and migration of photogenerated charge, thereby accelerating the production of H 2. This work shows the strong advantage and potential of non-precious metal efficient photocatalyst system for producing H 2 from deionized water and natural fresh water. The SrTiO 3 -TiO 2 -CaTiO 3 /Cu 2 O quaternary composite with dual p-n heterojunctions and dual type-II heterojunctions was successfully designed and prepared by a facile two-step synthesis process firstly, and it exhibited high hydrogen production rate in deionized water and natural fresh water. [Display omitted] • The multi-type heterojunctions can promote the separation of carriers. • Sr-Ti-Ca/Cu exhibited high H 2 production rate. [ABSTRACT FROM AUTHOR]

The magnesium phosphate (Mg-P) crystallization based on anaerobic ammonia oxidation is of interest for simultaneous nitrogen and phosphorus removal in wastewater treatment due to cost-effectiveness. Understanding the role of extracellular polymeric substances (EPS) in crystal growth is pivotal for bio-induced Mg-P crystallization. In this work, the effects of EPS in Mg-P crystallization were thoroughly investigated. Results indicated that EPS decreased the initial crystallization rate but slightly improved the final crystallization yield. The maximum removal efficiencies of Mg and P ions increased by 2.8 % and 3.1 %, respectively, when EPS concentration was 80 mg/L. Additionally, the presence of EPS enhanced Mg 3 (PO 4) 2 ·10 H 2 O production and facilitated the formation of larger rhombic plate-like structures crystals (maximum particle size increased by 215 %). Analysis of EPS composition changes during the crystallization process and characterization of the final crystals suggested that tryptophan-like proteins preferentially involved in the Mg-P crystallization process, while β-sheet proteins potentially influencing crystal morphology. Furthermore, the formation of phosphate ester groups, hydrogen bonding, and COOH-Mg2+ complexes were considered triggering factors for the interaction between EPS and Mg-P crystals. This study elucidated the underlying mechanism of EPS on Mg-P crystallization, further enhancing the understanding of the interaction between inorganic mineralization processes and microorganisms. [Display omitted] • Extracellular polymeric substances (EPS) affected Mg-P crystallization. • EPS promoted the generation of more Mg 3 (PO 4) 2 ·10 H 2 O. • EPS facilitated the formation of larger and thicker crystals. • The interaction between EPS and Mg-P crystals was elucidated. • Tryptophan-like and β-sheet proteins were mainly responsible for the interaction. [ABSTRACT FROM AUTHOR]

Darrieus–Landau (D-L) instability can cause significant acceleration in freely expanding spherical flames, which can lead to accidental large-scale gas explosions. To evaluate the potential of using high-pressure lab-scale experiments to predict the onset of cellular instabilities in large-scale atmospheric explosions, experimental measurements of the cellular instabilities for hydrogen and methane mixtures are conducted, in laboratory spherical explosions at elevated pressures. These measurements are compared with those from several large-scale atmospheric experiments. Comprehensive correlations of the pressure effect on a critical Karlovitz number, K c l , together with those of strain rate Markstein number, M a s r , are developed for hydrogen/air mixtures. The regime of stability reduces for all mixtures, as M a s r becomes negative. Values derived from large-scale experiments closely follow the same correlation of K c l with M a s r . As a result, the extent of the regime where the laminar explosion flames become unstable can be predicted as a function of M a s r and pressure. • Onset of instabilities of methane/hydrogen/air flames was studied and presented. • Flame speeds, critical radius, Karlovitz factor and strain rates were derived. • Correlations between small and large scale were developed and presented. • Such correlations can predict the instability in large-scale atmospheric explosions. • Effects of pressure and hydrogen fraction on the onset of instability were analyzed. [ABSTRACT FROM AUTHOR]

Particle image velocimetry (PIV) was employed to investigate the disturbance of unstable laminar hydrogen-air outwardly propagating spherical flames in a spherical explosion vessel. Both the flame speed and gas velocities exhibit acceleration due to the wrinkled flame surface. This acceleration occurs throughout the cycle of strong and weak acceleration phases, which is driven by the division and expansion of cells across the flame front. The flame speed acceleration exponent, α, and the gas velocity ahead of the flame acceleration exponent, α g , are nearly identical. This suggests a close interrelation between the self-acceleration of flame speed (S n) and the gas velocity ahead of the flame front (u g). Stronger gas flow disturbances caused by more wrinkly flame surfaces are associated with smaller cell sizes. Furthermore, the power spectral density displayed by the flow ahead of the flame front shows remarkable similarity to the fluctuation observed in the flame front. This suggests that the driver for gas disturbance generated ahead of the flame front can be attributed to the wrinkled flame front, whether arising from flame instability. The Power Spectral Density (PSD) of gas velocities and flame wrinkling display a steeper slope (-2.7) compared to isotropic turbulence within the inertial sub-range, where energy spectra decay at -5/3, as measured in a previous study. This observation suggests that gas flow induced by flame instability differs from isotropic turbulence. The normalized gas flow disturbance intensity, ( u g c ′ / u g c ‾), has been proposed as an evaluation parameter for studying intrinsic disturbance intensity. The increased gas flow disturbance intensity is closely associated with both the wrinkled flame surface and a smaller cell size. Empirical correlations for gas flow disturbance intensity are explored in terms of the laminar critical Karlovitz number (K cl), effective Lewis number (Le eff), and burnt gas Markstein number (Ma b). There is no obvious causal link between self-acceleration and self-disturbance. Both phenomena are attributed to the wrinkled flame surface. [ABSTRACT FROM AUTHOR]

β-glucosidases (BGLUs) hydrolyze the β -D-glycosidic bond with retention of anomeric configuration. BGLUs were associated with many aspects of plant physiological processes, in particular biotic and abiotic stresses through the activation of phytohormones and defense compounds. However, studies on systematic analysis of the stress- or hormone-responsive BGLU genes in plant are still rare. In this study, total 51 BGLU genes of the glycoside hydrolase family 1 were identified in the genome of the model legume plant Medicago truncatula , and they were classified into five distinct clusters. Sequence alignments revealed several conserved and characteristic motifs among these MtBGLU proteins. Analyses of their putative signal peptides and N-glycosylation site suggested that the majority of MtBGLU members have dual targeting to the vacuole and/or chloroplast. Many regulatory elements possibly related with abiotic stresses and phytohormones were identified in MtBGLU genes. Moreover, Microarray and qPCR analyses showed that these MtBGLU genes exhibited distinct expression patterns in various tissues, and in response to different abiotic stress and hormonal treatments. Notably, MtBGLU21 , MtBGLU22 , MtBGLU28 , and MtBGLU30 in cluster I were dramatically activated by NaCl, PEG, IAA, ABA, SA and GA3 treatments. Collectively, our genome-wide characterization, evolutionary analysis, and expression pattern analysis of MtBGLU genes suggested that BGLU genes play crucial roles in response to various abiotic stresses and hormonal cues in M. truncatula. • β -glucosidase genes of the glycoside hydrolase 1 family were identified in the genome of Medicago truncatula. • Gene structures, phylogenetic relationship, and expression profiles of all β -glucosidase genes were characterized. • We found MtBGLU21 , MtBGLU22 , MtBGLU28, and MtBGLU30 were dramatically activated by different treatments, indicating they may play important roles in Medicago development and stress tolerance. [ABSTRACT FROM AUTHOR]

• Measured laminar burning velocity for H2/CH4/air mixtures at elevated pressures. • Cellularity has been observed in all mixtures due to the DL and TD instabilities. • Strain-rate Markstein number varies with the pressure and hydrogen fractions. • A good agreement with predictions based on recently developed H2/CH4 mechanisms. Spherically expanding flame propagations have been employed to measure flame speeds for H 2 /CH 4 /air mixtures over a wide range of H 2 fractions (30 %, 50 %, 70 and 100 % hydrogen by volume), at initial temperatures of 303 K and 360 K, and pressures of 0.1, 0.5 and 1.0 MPa. The equivalence ratio (ϕ) was varied from 0.5 to 2.5 for pure hydrogen and from 0.8 to 1.2 for methane/hydrogen mixtures. Experimental laminar burning velocities and Markstein numbers for methane/hydrogen/air mixtures at high pressures, which are crucial for gas turbine applications, are very rare in the literature. Moreover, simulations using three recent chemical kinetic mechanisms (Konnov-2018 detailed reaction, Aramco-2.0-2016 and San Diego Methane detailed mechanism (version 20161214)) were compared against the experimentally derived laminar burning velocities. The maximum laminar burning velocity for 30 % and 50 % H 2 occurs at ϕ = 1.1. However, it shifts to ϕ = 1.2 for 70 % H 2 and to ϕ = 1.7 for a pure H 2 flame. The laminar burning velocities increased with hydrogen fraction and temperature, and decreased with pressure. Unexpected behaviour was recorded for pure H 2 flames at low temperature and ϕ = 1.5, 1.7 wherein u l did not decrease when the pressure increased from 0.1 to 0.5 MPa. Although, the measurement uncertainty is large at these conditions, the flame structure analysis showed a minimum decline in the mass fractions of the active species (H, O, and OH) with the rise in the initial pressure. Markstein length (L b) and Markstein number (Ma b and Ma sr) varied non-monotonically with hydrogen volume fraction, pressure and temperature. There was generally good agreement between simulations and experimentally derived laminar burning velocities, however, for experiments of rich-pure hydrogen at high initial pressures, the level of agreement decreased but remained within the limits of experimental uncertainty. [ABSTRACT FROM AUTHOR]

A series of Tm 3+ and Dy 3+ codoped BaWO 4 phosphors with tunable shapes were controllably synthesized by a facile solvothermal method. The effects of ratio of ethylene glycol (EG) and water on the morphologies of BaWO 4 structures are systematically studied. It was discovered that the reason for these morphological changes is based on the reaction speed of the kinetic control, which relates to the strong chelating abilities of ethylene glycol. And when the solvent is pure ethylene glycol, the peanut-like BaWO 4 :Dy 3+ has the strongest emission intensity. Moreover, the emission color of the phosphors varied from blue (0.232, 0.180) to white (0.268, 0.250) by controlling Dy 3+ ions content with a fixed Tm 3+ concentration. The energy transfer mechanism was investigated in detail. With increasing the doped concentration of Dy 3+ ions, the energy transfer efficiency of BaWO 4 :0.005Tm 3+ ,yDy 3+ increased gradually and reached as high as 63% when the Dy 3+ doped concentration is 0.03. The critical distance R C calculated by the spectral overlap method is about 19.93 Å, and it is in good agreement with that obtained using the concentration quenching method (19.70 Å), indicating that the electric dipole-dipole interaction is the main energy transfer mechanism for BaWO 4 :Tm 3+ ,Dy 3+ phosphors. [ABSTRACT FROM AUTHOR]

A series of LiGd(MO 4 ) 2 : Sm 3+ , Tb 3+ (M = Mo, W) phosphors was prepared by a conventional solid state reaction method. Powder X-Ray diffraction (XRD) analysis reveals that the compounds are of the same structure type. Their luminescent properties have been studied. The optimal doping concentrations are 8% for Sm 3+ and 18% for Tb 3+ in the LiGd(MoO 4 ) 2 host. Sm 3+ and Tb 3+ have different sensitivity to the Mo/W ratio. For LiGd(MoO 4 ) 2-X (WO 4 ) X : Sm 3+ (X = 0, 0.4, 0.8, 1.2, 1.6, 2.0), the strongest emission intensity is 1.766 times than that of the weakest, while 171 times for LiGd(MoO 4 ) 2-X (WO 4 ) X : Tb 3+ . The experimental results show that Mo/W ratio strong influences on the properties of LiGd(MoO 4 ) 2-X (WO 4 ) X : Tb 3+ . With the increasing of WO 4 2− groups concentration, the shape of characteristic excitation peaks of Tb 3+ is almost the same and the excitation intensity gradually increase. Moreover, the energy transfer from Tb 3+ to Sm 3+ has been realized in the co-doped phosphors. The experimental analysis and theoretical calculations reveal that the quadrupole–quadrupole interaction is the dominant mechanism for the Tb 3+ →Sm 3+ energy transfer. Therefore, luminous intensity can be adjusted by different sensitivities to matrix composition and energy transfer from Tb 3+ →Sm 3+ . By this tuning color method, white-light-emitting phosphor has been prepared. The excitation wavelength is 378 nm, and this indicates that the white-light-emitting phosphor could be pumped by near-UV light. [ABSTRACT FROM AUTHOR]

In annular two-phase gas-liquid flow, the liquid film on the wall consists of relatively quiescent substrate regions which are traversed by large amplitude, high velocity waves known as disturbance waves. The turbulent disturbance wave regions have relatively high average heat transfer coefficients (low average wall temperatures) compared to the (probably laminar) substrate regions. Nevertheless, there is evidence that nucleate boiling (necessitating a higher wall temperature) occurs first in the wave regions. This paper explores the hypothesis that wall temperature fluctuations due to turbulence in the disturbance waves are of sufficient magnitude to give localized triggering of nucleation sites and hence nucleate boiling. This hypothesis was explored using Computational Fluid Dynamics (CFD). The turbulence was modelled using wall-resolved LES. The results lend weight to the hypothesis that the nucleate boiling observed in disturbance waves is due to transient local high temperatures induced by the turbulence. [ABSTRACT FROM AUTHOR]

Well-defined GdPO 4 nanocrystals were successfully prepared through the facile hydrothermal synthesis route followed by a heat treatment. The microstructure, morphologies and photoluminescence properties of as-prepared samples were investigated via X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectroscopy and luminescence decay, which were significantly affected by the reaction conditions (phosphorus source, acidity of hydrothermal process and surfactants). It is found that Sodium dodecyl sulfate (SDS) as a shape modifier has the dynamic effect by adjusting the growth rate of different facets, resulting in morphology transformation of GdPO 4 · H 2 O from the nanowire (without SDS) to the nanorod (with SDS). Strong yellow-orange emissions could be obtained in Sm 3+ and Eu 3+ ions codoped GdPO 4 phosphors under ultraviolet light irradiation. Moreover, the energy transfer mechanism from Sm 3+ to Eu 3+ has been studied and proved to be a dipole-dipole interaction mechanism. These results show this yellow-orange-emitting phosphors material may have potential applications in field-emission displays. [ABSTRACT FROM AUTHOR]