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Carrier mobility in titanium dioxide (TiO2) systems is a key factor for their application as energy materials, especially in solar cells and lithium-ion batteries.

Absorbing aerosols from dust, industrial emissions and biomass combustion have a strong impact on solar radiation in the atmosphere, and they are considered to be an important source of regional air pollution[1], especially in East Asia, where the degree of variation of absorbable aerosols is very large, so it will have a significant impact on regional climate change. Aerosol single scattering albedo (SSA) is a key variable of aerosol absorption and a key metric of climate impact. Accurate estimation of SSA is crucial to reduce uncertainties in the study of atmospheric pollution and climate effects.The aerosol model of the current aerosol inversion algorithm is several typical regional aerosol candidate models obtained by cluster analysis of selected ground observation data[2]. These independent candidates' aerosol models result in the estimation of SSA being just a few simple constants, leading to a large bias in the results of SSA.In the current study, an atmospheric radiative transfer model parameterized by a two-stream approximation is used to construct a genetic algorithm for application to geostationary satellite Himawari-8 / AHI data to retrieve the aerosol SSA. The inversion process is constrained by AOD and the surface bidirectional reflectance distribution function (BRDF). Using this algorithm, hourly SSA data were retrieved was retrieved during day time.The algorithm was tested using the hourly L1 grid data of AHI from 00:00 to 07:00(UTC) from January to March 2020. Examples of the 10km satellite-retrieved SSA on March 15, 2020, are shown in Fig. 1. It can be seen that the SSA value in East China is significantly lower than in other regions. This may be due to the developed industries in southern cities that emit a large number of black carbon aerosols, while the temperature in winter is low, and the aerosol particles are not easily diffused, resulting in the SSA value of some areas maintaining a stable low value.To evaluate the retrieval SSA results, AERONET V3 datasets were used for validation. The AERONET datasets were selected in East Asia. Fig. 2 shows the scatter plots of AHI SSA retrievals versus AERONET at 470nm, (a) all AOD, and (b) only high aerosol loading (AOD>0.4 at 470nm), respectively. This indicates that the algorithm has great advantages for SSA inversion of heavy pollution conditions.The retrieval results from three months of AHI data were evaluated against the ground-based AERONET measurements. The AHI SSA shows good agreement with AERONET measurements, especially in heavy pollution conditions. This algorithm has been proven to be to characterize the temporal and spatial distribution of aerosol SSA.

Aerosol Optical Depth (AOD), quantifying the amount of aerosol in the atmosphere, is widely regarded as a crucial indicator for research on atmospheric physics and regional air quality. At present, the inversion of AOD from observation of satellite remote sensing sensors has become the main technology for large-scale monitoring of aerosol load. The Huaihai Economic Zone is the connecting belt of two key areas of atmospheric governance (the Yangtze River Delta and the Beijing-Tianjin-Hebei region, China), and it has been suffering from air pollution for many years and few studies of AOD focus on this region. Therefore, the spatial and temporal characteristics of the AOD are explored using MODIS AOD data and AVHRR AOD data in this region during the period from 1982 to 2021 in this study. The correlation coefficients between the AOD of satellite observation and actual air pollution were analyzed by combining PM2.5 pollutant concentration and air quality index (AQI) data. The results showed that the AOD is higher in the northwest than in the southeast, and it is different from season to season. The annual variation of AOD in the Huaihai Economic Zone is a W-shaped trend from 1982 to 2011, while the trend of annual AOD is decreasing after 2011. In terms of seasons, the whole differences in AOD are evident, exhibiting AOD values in summer > those in spring > those in autumn > and those in winter. Furthermore, it indicated that the quarterly and monthly variation of the AOD tends to be flat in recent years. Since 2015, the concentration of PM2.5 has continued to decline, the same as that of AQI. Meanwhile, the quarterly and monthly differences in PM2.5 are still obvious, with higher PM2.5 in winter and lower PM2.5 in summer. However, it also represented that PM2.5 is significantly higher in spring than in autumn from 2015 to 2018, which is the opposite for 2019 to 2021. Lastly, the correlation between AOD and PM2.5/AQI is also given; i.e., the correlation coefficients of AOD with PM2.5/AQI are 0.84/0.82, with the highest correlation coefficient in autumn (R = 0.86/0.91) and the lowest in winter (R = 0.46/0.48).

Loop-mediated isothermal amplification (LAMP) is a popular DNA amplification method. Gold nanoparticles (AuNPs) were reported to enhance the efficiency of LAMP, although the underlying mechanism remained elusive. Since AuNPs strongly adsorb a range of ligands, preadsorbed ligands cannot be easily displaced. In this work, we systematically investigated the effect of surface-modified AuNPs on LAMP by varying the order of mixing of AuNPs with each reagent in the LAMP system (Mg

Organic-inorganic metal halides (OIMHs) exhibit excellent photoelectric properties; however, their high-temperature light-emission stability requires further improvement. Here, we report three isostructural OIMHs (C

A wide bandgap is an essential requirement for a nonlinear optical (NLO) material. However, it is very challenging to simultaneously engineer a wide bandgap and a strong second-harmonic generation (SHG) response, particularly in NLO materials containing second-order Jahn-Teller (SOJT) distorted units. Herein, we employ a bandgap engineering strategy that involves the dual fluorination of two different types of SOJT distorted units to realize remarkably wide bandgaps in the first examples of 5d

The zero-dimensional CsPbBr3/CdSe heterojunction facilitates charge transfer through Pb–Se and Cd–Br bonds and provides abundant active sites in the unique structure, resulting in efficient photocatalytic CO2 reduction.

0D Mn2+-based bromides with [MnBr4]2− tetrahedral and [Mn3Br12]6− octahedral units are designed, which aims at clarifying the relationship between the coordination units of Mn2+ and tunable emissions.

Hierarchically porous N-doped carbon nanofibers anchored with low-loaded FeCo sites (FeCo@PCNFs) were fabricated via the facile electrospinning method followed by carbonization, showing excellent performance for the ORR and primary zinc–air battery.

Ultraviolet crystal PbBe2B2O6 with an unprecedented π–π interacting BeBO5 group, has wide optical-transparency, whole-spectrum phase-matching, and large nonlinear-optical effects.

A simple and effective plasma-activated strategy is employed to synthesize a MOF-based single-atom copper catalyst, which contains abundant low-coordinated copper sites for high-performance CO2 electroreduction to CH4.

Negative and zero thermal expansion (NTE and ZTE) materials are widely adopted to eliminate the harmful effect from the "heat expansion and cool contraction" effect and frequently embrace novel fundamental physicochemical mechanisms. To date, the manipulation of NTE and ZTE materials has mainly been realized by chemical component regulation. Here, we propose another method by making use of the anisotropy of thermal expansion in noncubic single crystals, with maximal tunability from the integration of linear NTE, ZTE and positive thermal expansion (PTE). We demonstrate this concept in borate optical crystals of AEB

As critical components in modern aerospace productions, rolling element bearings (REBs) generally work under varying speed conditions, which brings great challenges to their operating health monitoring. Some novel time–frequency decomposition (TFD) algorithms are established recently to extract nonlinear features from the non-stationary signals effectively, which are promising for realizing fault diagnosis of REBs under varying speed conditions. However, numerous personal experiences must be incorporated and the anti-noise performance of these methods needs to be further enhanced. Given these issues, a synchronous chirp mode extraction (SCME) - based REB fault diagnosis method is proposed for the health monitoring of REBs under varying speed conditions in this study. It mainly consists of following two parts. (a) The shaft rotational frequency (SRF) is initially estimated from the low-frequency band of the vibration signal. Simultaneously, an adaptive refining strategy is incorporated to obtain a suitable bandwidth parameter. (b) A cycle-one-step estimation frame is constructed to extract synchronous modes from the envelope waveform of the vibration signal. Meanwhile, a synchronous mode spectrum (SMS) is generated using the information of the extracted synchronous modes, which is a novel REBs fault diagnosis technique with tacholess and resampling-free. In contrast to the current TFD algorithms, the proposed method needs fewer input parameters and owns a well anti-noise performance because there is no iterative optimization in the procedure of construction of SMS. As a result, the health conditions of REBs are evaluated by detecting the exhibited features in the SMS. Simulations and experiments are conducted to validate the effectiveness of the proposed method in terms of REB fault diagnosis. Analysis results demonstrate that the proposed method outperforms the current TFD algorithm and the conventional order tracking technique for fault diagnosis of REB under varying speed conditions.

Revealing the origin of self-trapped excitons is a prerequisite for further improving the photoluminescence efficiency of low-dimensional organic perovskites. Here, the microscopic formation mechanism of intrinsic self-trapped excitons in one-dimensional (1D) C

Existing generative adversarial networks (GAN) have potential in data augmentation and in the intelligent fault diagnosis of bearings. However, most relevant studies only focus on the fault diagnosis of rotating machines with sufficient fault-type samples, and some rare fault-type samples may be missing in training in practical engineering. To address those deficiencies, this paper presents an intelligent fault diagnosis method based on the dynamic simulation model and Wasserstein generative adversarial network with gradient normalization (WGAN-GN). The dynamic simulation model of bearing faults is constructed to obtaining simulation signals to replace and complement the missing fault samples, which are combined with the measured signals as training data and then input into the proposed WGAN-GN model for expanding and enhancing the data. To test the effectiveness of the simulated samples, a fault classification model constructed by stacked autoencoders (SAE) is used to classify the enhanced dataset. According to the results, the proposed model performs well when used to diagnose faults under missing samples and is preferable to other methods.

Negative area compressibility (NAC) is a counterintutive “squeeze-expand” behavior in solids that is very rare but attractive due to possible pressure-response applications and coupling with rich physicochemical properties. Herein, NAC behavior is reported in palladium diselenide with a large magnitude and wide pressure range. We discover that, apart from the rigid flattening of layers that has been generally recognized, the unexpected giant NAC effect in PdSe2 largely comes from anomalous elongation of intralayer chemical bonds. Both structural variations are driven by intralayer-to-interlayer charge transfer with enhanced interlayer interactions under pressure. Our work updates the mechanical understanding of this anomaly and establishes a new guideline to explore novel compression-induced properties.

The strong mutual coupling of and even the opposite change in the key parameters, such as the band gap (Eg) and second-order harmonic generation (SHG), leads to the extreme scarcity in high-performance IR nonlinear optical (NLO) chalcogenides. Herein, we report 8 new sulfides, Na2Ba[(AgxNa1-x)2Sn2S7] (1, x = 0; 1 series, x = 0.1-0.6; Na2Ba[(Li0.58Na0.42)2Sn2S7], 1-0.6Li); Na2Sr[Cu2Sn2S7] (2); and Na2Ba[Cu2Sn2S7] (3). We use the structural tolerance factor ( [[EQUATION]] ) to connect the chemical composition, crystal structure, and NLO properties. Guided by these correlations, a better balance between Eg and SHG is realized in 1, which exhibits a large Eg of 3.42 eV and excellent NLO properties (SHG: 1.5 × AGS; laser-induced damage threshold: 12 × AGS), representing the best performance among the known Hg- or As-free sulfides to date.

Polar Ce3F4(SO4)4, which possesses a strong SHG effect and sufficient birefringence, was rationally designed through fluorination degree modulation.

Deep-ultraviolet (deep-UV) nonlinear optical (NLO) crystals are key materials in creating tunable deep-UV lasers for frequency conversion technology. However, practical application of the sole usable crystal, KBe2 BO3 F2 , has been hindered by the high toxicity of beryllium and its layering tendency in crystal growth. Herein, we report a beryllium-free deep-UV NLO material NaSr3 (OH)(B9 O16 )[B(OH)4 ] (NSBOH), synthesized by a covalent bond modification strategy under hydrothermal conditions. Moisture-stable NSBOH exhibits strong second-harmonic generation (SHG) at 1064 nm (3.3 × KH2 PO4 ) and 532 nm (0.55 × β-BaB2 O4 ), both amongst the largest powder SHG responses for a deep-UV borate, with good phase-matchability and a short wavelength cutoff edge (below 190 nm). NSBOH possesses a 3D covalent anionic [B9 O19 ]∞ honeycomb-like framework with no layering. The Sr2+ and Na+ ions, residing in the cavities of the anionic framework, act as templates for the assembly and favorable alignment of NLO-active groups, resulting in an optimal balance between strong SHG activities and wide UV transparency. These merits indicate NSBOH is a very attractive candidate for deep-UV NLO applications.

Second-harmonic-generation (SHG) efficiency and birefringence are two crucial parameters for nonlinear optical (NLO) crystals. However, the simultaneous optimization of these two key parameters rem...

A large number of oxides that adopt the centrosymmetric (CS) garnet-type structure (space group Ia3d) have been widely studied as promising magnetic and host materials. Hitherto, no noncentrosymmetric (NCS) garnet has been reported yet, and a strategy to NCS garnet design is therefore significant for expanding the application scope. Herein, for the series A3A'3Zn6Te4O24 (A = Na, A' = La, Eu, Nd, Y, and Lu), we demonstrated that the structural symmetry evolution from CS Ia3d (A' = La) to NCS I4122 (A' = Eu, Nd, Y, and Lu) could be achieved due to the A-site cationic ordering-driven inversion symmetry breaking. Na3A'3Zn6Te4O24 (A' = rare earth) are the first garnets that possess NCS structures with A-site cationic ordering. Diffuse reflectance spectra and theoretic calculations demonstrated that all these NCS garnets are indirect semiconductors. Moreover, their potential applications as host materials for red phosphors and Na-ion conductors were also investigated in detail, which firmly confirmed the NCS structure and A-site cationic ordering. Our findings have paved the way to design NCS or even polar garnets that show intriguing functional properties, such as ferroelectricity, multiferroicity, and second harmonic generation.

Intense interests in mid-infrared (MIR) nonlinear optical (NLO) crystals have erupted in recent years due to the development of optoelectronic applications ranging from remote monitoring to molecular spectroscopy. Here, two polar crystals Ca3(TeO3)2(MO4) (M = Mo, W) were grown from TeO2-MO3 flux by high-temperature solution methods. Ca3(TeO3)2(MoO4) and Ca3(TeO3)2(WO4) are isostructural, which feature novel structures consisting of asymmetric MO4 tetrahedra and TeO3 trigonal pyramids. Optical characterizations show that both crystals display ultrawide transparency ranges (279 nm to 5.78 μm and 290 nm to 5.62 μm), especially high optical transmittance over 80% in the important atmospheric transparent window of 3-5 μm, and superhigh laser damage thresholds (1.63 GW/cm2 and 1.50 GW/cm2), 54.3 and 50 times larger than that of state-of-the-art MIR NLO AgGaS2, respectively. Notably, they exhibit the widest band gaps and the loftiest laser-induced threshold damages among the reported tellurates so far. Moreover, Ca3(TeO3)2(MO4) exhibit type I phase matching at two working wavelengths owing to their large birefringence and strong second-harmonic generation responses from the distorted anions, as further elucidated by the first-principles calculations. The above characteristics indicate that Ca3(TeO3)2(MO4) crystals are high-performance MIR NLO materials, especially applying in high-power MIR laser operations.