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The energy and water vapor exchange between the land surface and atmospheric boundary layer plays a critical role in regional climate simulations. This paper implemented a hybrid data assimilation and machine learning framework (DA-ML method) into the Weather Research and Forecasting (WRF) model to optimize surface soil and vegetation conditions. The hybrid method can integrate remotely sensed leaf area index (LAI), multi-source soil moisture (SM) observations, and land surface models (LSMs) to accurately describe regional climate and land–atmosphere interactions. The performance of the hybrid method on the regional climate was evaluated in the Heihe River basin (HRB), the second-largest endorheic river basin in Northwest China. The results show that the estimated sensible (H) and latent heat (LE) fluxes from the WRF (DA-ML) model agree well with the large aperture scintillometer (LAS) observations. Compared to the WRF (open loop – OL), the WRF (DA-ML) model improved the estimation of evapotranspiration (ET) and generated a spatial distribution consistent with the ML-based watershed ET (ETMap). The proposed WRF (DA-ML) method effectively reduces air warming and drying biases in simulations, particularly in the oasis region. The estimated air temperature and specific humidity from WRF (DA-ML) agree well with the observations. In addition, this method can simulate more realistic oasis–desert boundaries, including wetting and cooling effects and wind shield effects within the oasis. The oasis–desert interactions can transfer water vapor to the surrounding desert in the lower atmosphere. In contrast, the dry and hot air over the desert is transferred to the oasis from the upper atmosphere. The results show that the integration of LAI and SM will induce water vapor intensification and promote precipitation in the upstream of the HRB, particularly on windward slopes. In general, the proposed WRF (DA-ML) model can improve climate modeling by implementing detailed land characterization information in basins with complex underlying surfaces.

We report first-principles calculations of cluster silica with and without interstitial Bi0 atom. The size and radial distance of “Si-O-Si” rings are considered to study the equilibrium position of interstitial Bi0 atom in Bi-doped silica optical fiber. Our results reveal that the interstitial Bi0 atom is most likely to stay around ~ 2 A from the center of 6-membered rings. By comparing the transition energy levels with Bi0 atomic spectral data, we find that the transition 2D3/2(1) → 4S3/2 of interstitial Bi0 atom leads to the NIR emission estimated as ~ 1265 nm in Bi-doped silica optical fiber. Our methods will be effective to confirm bismuth-active centers for different valence states of Bi atom.

Razdobreev et al. claim that the energy level diagrams discussed in our paper are absolutely inconsistent with the experimental data. We carefully studied the comment and concluded that the claims on our paper are largely invalid. We maintain that the proposed diagrams in our paper can explain the luminescence in the spectral range of 1.4–1.7 µm and the spectral region 1.15 µm. Our calculated results are reliable for non-defective silica fiber models.

Two phenoxazine derivatives 1 and 2 were synthesized and their photoluminescent properties were systematically investigated. These two compounds presented crystallization-induced emission (CIE) with polymorphism-dependent emission (PDE). Compound 1 presented two single crystal structures with maximum emission wavelengths of 540 nm and 560 nm, while compound 2 possessed three single crystal structures with maximum emission wavelengths of 516 nm, 547 nm, and 556 nm, respectively. Moreover, compound 1 showed reversible mechanochromic luminescence by grinding/heating or solvent fuming processes.

The donor–acceptor design is a classic method of synthesizing new fluorescent molecules. In this study, a series of new fluorescent compounds (1–10) were synthesized based on 2-(3,5-bis(trifluoromethyl)phenyl)-quinazoline acceptor and various amino donors. The fluorescent emissions of 1–10 cover the spectrum from 414 nm to 597 nm in cyclohexane solutions with various amino donors on 4- or 7-positions of quinazoline. Ultimately, compounds 1 and 2 presented the highest photoluminescence quantum yield (QY) over 80%, while compound 10 provided the largest Stokes shift (161 nm) in cyclohexane. Most of them have strong emissions in aggregated states such as in nanoparticles, in powders, in crystals and in films. Mechanochromic properties were observed for compounds 1, 2, 4 and 7. Furthermore, blue OLEDs were fabricated by using compound 2 or 7 as the active layer.

A fluorescent D–A–D′ triad (1), composed of monocarbaborane, benzothiadiazole and triphenylamine, was synthesized. By replacing monocarbaborane with phenyl (Ph), p-methoxyphenyl (PMP) or 4-pyridinyl (Py), three analogs (2, 3, and 4) were prepared for comparison. Monocarbaborane is an electron donating group based on the comparative analysis of NMR spectra and the systematic investigation of their photophysical properties. Triad 1 emits bright-yellow light in THF solution with the highest quantum yield and the longest decay time among these compounds. It tends to form nanoparticles in aqueous THF solution. The in situ generated nanoparticles might be used to detect silver ions with high sensitivity and high selectivity. By holding the molecules via multiple CH⋯π interactions and electrostatic forces between the tetraethylammonium cation and the cage, a sheet-like arrangement of 1 is formed in the solid state with the smallest crystal density that provides the maximal possibility of mechanofluorochromism from the crystalline to the ground form. Moreover, by doping 1 in PVK, a white OLED is obtained.

A series of butterfly-shaped D–A–D and D–A–A compounds composed of a benzothiadiazole core and corresponding terminal alkynes were synthesized. Their photophysical properties in different states (solution, film, crystal, and powder) were investigated. Meanwhile, the linear-shaped compounds were prepared accordingly for the comparative investigation of their photophysical properties. Three phenomena (aggregation caused quenching, crystal induced emission, and aggregation induced emission enhancement) were all observed for the butterfly-shaped compounds. Although the linear-shaped compounds emitted brighter light in pristine powders with higher quantum yields, the butterfly-shaped compounds formed crystals and emitted colorful light from 473 nm to 622 nm in the crystalline state. Moreover, most of them exhibited a mechanochromic character. The color of 2POZ-56 could be reversibly tuned from yellow to red by grinding and fuming. Furthermore, polymorphism-dependent emission was observed for 2POZ-56, allowing for its use as an emissive layer in white organic light emitting diodes.

We present first-principles combined GW and Bethe-Salpeter equation on passivation effect between ODC(I) and H/F atoms. The injection of H or F atoms help to form the robust Si H or Si F bond which increase the optical band gap, erase the defect state of ODC(I) at 0.74 eV and improve radiation toughness. The reaction of ODC(I) defect with a H atom or F atoms is barrierless, the Si O length near the ODC(I) sites are all gradually getting shorter and bond energy are getting stronger. Coupled with the atomic structures and electro-optic properties, we found out that F is the better passivator.

F and Cl atoms are always brought by the process of wet etching for fused silica devices, which dramatically influence the performance of the devices. The adsorption characteristics of F and Cl atoms with two main fused silica surface defects (E', NBOHC) were investigated on the basis of first-principle methods. Through the comparison of absorption capacity of different surface defects, we found that E' has larger capability to adsorb halogen atoms than NBOHC, and F atom is easier to be trapped by surface defects than Cl atom. Furthermore, the electronic structure and the bonding nature for surface defects are also studied and the calculations show that the introduction of F and Cl atoms will lead to the disappearing of defect states in band gap. And this adsorption process of F and Cl atoms on fused silica surface can be considered to chemical adsorption.

Monovalent bismuth-related centers in pure silica optical fiber are calculated by using first-principle methods. Transition energy levels of three different structural models are investigated on the basis of the time-dependent density functional theory (TDDFT). Compared with the experimental data of near-IR luminescence, our calculated results suggested that luminescence near 1492 nm is likely caused by SiOBi configuration; and luminescence at 1147 nm and 1403 nm may be caused by interstitial Bi2O molecule. Moreover, SiBi configuration, which might be the origin of the luminescence near 1629 nm, is difficult to directly form because of its relatively high formation energy.

We report silica fiber with trivalent bismuth (Bi3+) in first-principles calculations. The influences of members of “Si–O–Si” rings are considered to study atomic structures, frontier molecular orbital and optical properties of Bi-doped optical fiber. Our results reveal that the luminescence of Bi3+-doped optical fiber is the result of a combination of Bi3+ ions and silica matrix. Different ring structures affect the luminescence properties, which explained why Bi3+-doped silica fiber usually cover a broad spectral range from the UV to visible light.

Various amino benzothiadiazoles (Am-BTDs) are synthesized and their photophysical properties in different states (solution, film, crystal, and powder) are investigated. Unusual anti-Kasha's emission is observed for those compounds with a strong electronic coupling effect between the donor and the acceptor which directly results in the white emission of those compounds in dilute solutions. Among these Am-BTDs, some of them can be utilized as fluorescent chemosensors in sensing gaseous ammonia, and some of them can be developed for detecting fluoride anions with high selectivity and high sensitivity. Moreover, aggregation caused quenching is not observed for these compounds in the solid state. They are emissive in films, crystals and powders with high color purity and moderate efficiencies. The emission color could be tuned from yellow to red according to the varying amino groups. Furthermore, they can be used as an emissive layer in organic light emitting diodes.

Hydrogen peroxide (H2O2) has been associated as the most important member of reactive oxygen species (ROS) for a long time. Two novel fluorescent probes (P1 and P2) are synthesized and characterized for rapid detection of H2O2. In the presence of base, the probes provide remarkable changes in optical properties with extremely fast response towards H2O2 based on the cleavage of C O bond and the principle of excited state intramolecular proton transfer (ESIPT) or photo-induced electron transfer (PET).

Unmanned aerial vehicle (UAV) remote sensing and deep learning provide a practical approach to object detection. However, most of the current approaches for processing UAV remote-sensing data cannot carry out object detection in real time for emergencies, such as firefighting. This study proposes a new approach for integrating UAV remote sensing and deep learning for the real-time detection of ground objects. Excavators, which usually threaten pipeline safety, are selected as the target object. A widely used deep-learning algorithm, namely You Only Look Once V3, is first used to train the excavator detection model on a workstation and then deployed on an embedded board that is carried by a UAV. The recall rate of the trained excavator detection model is 99.4%, demonstrating that the trained model has a very high accuracy. Then, the UAV for an excavator detection system (UAV-ED) is further constructed for operational application. UAV-ED is composed of a UAV Control Module, a UAV Module, and a Warning Module. A UAV experiment with different scenarios was conducted to evaluate the performance of the UAV-ED. The whole process from the UAV observation of an excavator to the Warning Module (350 km away from the testing area) receiving the detection results only lasted about 1.15 s. Thus, the UAV-ED system has good performance and would benefit the management of pipeline safety., Remote Sensing, 12 (1), ISSN:2072-4292

The Cu(II)-catalyzed electrophilic cyclization reaction between o-hydroxyarylenaminones and 3-diazoindolin-2-imines furnished 3-indolyl-4 H-chromen-4-ones in moderate to good yields with a broad substrate scope. Several pyrido[2,3- b:6,5- b']diindoles and one pyrazino[2,3- b:5,6- b']diindole were also obtained as byproducts in some cases and tested for their photophysical properties. Pyrido[2,3- b:6,5- b']diindoles exhibited solvent-dependent emission, while pyrazino[2,3- b:5,6- b']diindole emitted strong luminescence with 25.6% quantum yield in cyclohexane.

Three green-emitting compounds 1–3 based on 2-aryl-3-cyanobenzofuran fluorophore tethered with aggregation-induced emission active (AIE-active) tetraphenylethene (TPE) were designed and synthesized. p-Methoxyphenyl (PMP) was installed on the 5-, 6-, and 7-positions of 2-aryl-3-cyanobenzofuran for systematically investigating the substituent effect on their photophysical properties in solutions, nanoparticles, films, crystals, as well as powders. The aggregation-caused quenching (ACQ) problem arising from the π–π stacking between fluorophores was surmounted by covalently bonding the TPE unit. Thus, these compounds emitted green light in solids, and the film's quantum yield approached 50.1%. Red-shifted mechanochromism was observed for the crystalline state with a small crystal density. The best OLED performance was achieved using the compound with PMP occupied at the 6-position of 2-aryl-3-cyanobenzofuran, which possessed the longest efficient conjugation length.

Copper-catalyzed cascade synthesis of 2-aryl-3-cyanobenzofurans from o-hydroxybenzaldehydes and arylacetonitriles in the presence of copper acetate and sodium methoxide is reported. The synthesized 2-aryl-3-cyanobenzofurans emit bright blue under UV light with a quantum yield up to 88.9%.

The role of static disorder properties for oxygen deficiency center (ODC(I)) has been investigated in 96-atoms fused silica supercell by first-principles methods. 64 ODC(I) defect structures were built and the calculations show a linear relationship between the formation energy and Si–Si bond. An accurate electronic structure as well as the optical absorption spectra of ODC(I) defect is obtained using quasi-particle GW0 + BSE method. With the increase of formation energy, defect states levels near the bottom of the conduction band (BCB) have an obvious split, which causes variations in the optical absorption. Our results provide an analysis corresponding to the relationship between formation energy, local structure and defect states in fused silica and emphasize an importance of orderly rule in disorder system.

Rhodium-catalyzed C-H activation/annulation reactions of ketenimines with N-methoxybenzamides furnished 3-aminoisoindolin-1-ones and 3-(diarylmethylene)isoindolin-1-ones. The synthesized 3-(diarylmethylene)isoindolin-1-ones exhibited aggregation induced emissions in aqueous tetrahydrofuran solution and strong green-yellow emissions in solids.

Ground measured component radiative temperatures are basic inputs for modelling energy and hydrological processes and for simulating land surface temperature (LST) as “viewed” by remote sensors. However, knowledge of factors affecting the component temperatures and about their potential for upscaling LST over sparsely vegetated surfaces with high heterogeneity is still lacking. Here, a MUlti-Scale Observation Experiment on land Surface temperature (MUSOES) was performed under HiWATER over an arid sparsely vegetated surface. Component temperatures were obtained with different instruments on multiple spatial scales; for LST upscaling, a three-dimensional scene model was employed for two forest stations (MFS and PFS) and a two-dimensional model for a shrub station (SUP). Results show that intrinsic characteristics contribute to the temperature variability between different components and even within a single component. Using a thermal infrared (TIR) imager at MFS, average temperature difference of 24.9 K between sunlit bare soil and tree canopy was found; different components exhibit different internal temperature differences at direction-level and pixel-level. Furthermore, illumination conditions, viewing directions, and instrument types significantly affected the measured component temperatures. The measurements of the TIR radiometer and the imager can deviate considerably (e.g. 14.9 K for sunlit bare soil at MFS). When the longwave radiometers were selected as target sensors, the component temperatures measured by the imager exhibit good potential for LST upscaling: the upscaled LST has MBD/RMSD values of 2.0 K/2.3 K at MFS and 2.0 K/2.5 K at PFS. The TIR radiometer’s measurements introduce large uncertainties into LST upscaling at MFS and PFS, but result in good accuracy at SUP, mainly due to its simpler land cover and surface structure. Findings from this study can benefit our understanding of factors affecting observations of component temperatures and the LST upscaling process and are, therefore, relevant for further studying the evaluation of satellite LST products.

Potassium carbonate-promoted coupling reactions between 3-diazoindolin-2-imines and nucleophiles were tested. By respectively applying 2-naphthalenols and 2-arylacetates as nucleophiles, 3-azoindoles and 3-hydrazonoindolin-2-imines were obtained in excellent yields. Moreover, 3-azoindol-2-amines could be used as NNO pincer ligands for boron and resulted in the formation of hexacycleborofluorides with their absorption around 580 nm in dichloromethane.

Copper-catalyzed cascade synthesis of 2-aryl-3-cyanobenzofurans from o-hydroxybenzaldehydes and arylacetonitriles in the presence of copper acetate and sodium methoxide is reported. The synthesized 2-aryl-3-cyanobenzofurans emit bright blue under UV light with a quantum yield up to 88.9%.

An optical probe based on colorimetric and ratiometric as well as chemiluminometric signal outputs is developed for the specific detection of hydrazine. On the basis of a Gabriel-type reaction, hydrazinolysis of a simple probe CF (4-phtalamide-N-(4'-methylcoumarin) naphthalimide) produces both the fluorescence of 7-amino-4-methylcoumarin with the max emission wavelength changed from 480 to 420 nm (along with a color change from yellow to transparent) and the luminol chemiluminescence activated by H2O2 with a max emission wavelength at 450 nm. The experimental detection limit of hydrazine is 3.2 ppb (0.1 μM). Selectivity experiments proved CF has excellent selectivity to hydrazine over other interfering substances. Probe CF was also successfully applied in the vapor hydrazine detection over other interfering volatile analytes. Furthermore, the probe CF loaded thin-layer chromatography (TLC) plate for vapor hydrazine detection limit is 5.4 mg/m(3) which is well below the half lethal dose of hydrazine gas for mice (LC50(mice), 330 mg/m(3)) and National Institute of Occupational Safety and Health's immediately dangerous to life or health limit (NIOSHIDLH, 66 mg/m(3)). With H2O2, only hydrazinolysis product luminol can be lighted at 450 nm, other species have no signal. Probe CF can also be used for the detection of hydrazine in HeLa cells.

A new probe based on the Gabriel mechanism was designed and first used for hydrazine detection with high selectivity against other amines in aqueous solution. Importantly, the probe could be used for gas-state discrimination of hydrazine with different concentrations. Additionally, probe 1 could also be applied for the imaging of hydrazine in living cells.