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Although the fusion of multispectral (MS) and hyperspectral (HS) images in remote sensing has become relatively mature, and different types of fusion methods have their own characteristics in terms of fusion effect, data dependency, and computational efficiency, few studies have focused on the impact of radiance extreme areas, which widely exist in real remotely sensed scenes. To this end, this paper proposed a novel method called radiance extreme area compensation fusion (RECF). Based on the architecture of spectral unmixing fusion, our method uses the reconstruction of error map to construct local smoothing constraints during unmixing and utilizes the nearest-neighbor multispectral data to achieve optimal replacement compensation, thereby eliminating the impact of overexposed and underexposed areas in hyperspectral data on the fusion effect. We compared the RECF method with 11 previous published methods on three sets of airborne hyperspectral datasets and HJ2 satellite hyperspectral data and quantitatively evaluated them using 5 metrics, including PSNR and SAM. On the test dataset with extreme radiance interference, the proposed RECF method achieved well in the overall evaluation results; for instance, the PSNR metric reached 47.6076 and SAM reached 0.5964 on the Xiong’an dataset. In addition, the result shows that our method also achieved better visual effects on both simulation and real datasets.

Water-soluble ligands based on a 1,10-phenanthroline core are relatively poorly studied compounds. Developing efficient and convenient syntheses of them would result in new interesting applications because of the importance of 1,10-phenanthrolines. In this manuscript, we describe novel and practical ways to introduce a carboxyl and, for the first time, a phenol and dithiocarboxyl group under mild reaction conditions. This strategy enables highly efficient and practical synthesis of suitable organosulfur compounds with high added value, high chemoselectivity, and a broad substrate range. We present the selective conversion of a hydroxydialdehyde in the form of 10-hydroxybenzo[h]quinoline-7,9-dicarbaldehyde into its derivative, unique hydroxydicarboxylic acid, by an oxidation procedure, giving 10-hydroxybenzo[h]quinoline-7,9-dicarboxylic acid. A similar procedure resulted in the formation of 9-methyl-1,10-phenanthroline-2-carboxylic acid by oxidation of commercially available neocuproine. An alternative method of obtaining 1,10-phenanthroline derivatives possessing carboxylic acid group can be based on the hydrolysis of ester or nitrile groups; however, this synthesis leads to unexpected products. Moreover, we apply Perkin condensation to synthesize a vinyl (or styryl) analog of 1,10-phenanthroline derivatives with phenol function. This reaction also demonstrates a new, simple, and efficient strategy for converting methyl derivatives of 1,10-phenanthroline. We anticipate that the new way of converting methyl will find wide application in chemical synthesis.

Abstract Developing an efficient and quality remote sensing (RS) technology using volume and efficient modelling in different aircraft RS images is challenging. Generative models serve as a natural and convenient simulation method. Because aircraft types belong to the fine class under the rough class, the issue of feature entanglement may occur while modelling multiple aircraft classes. Our solution to this issue was a novel first-generation realistic aircraft type simulation system (ATSS-1) based on the RS images. It realised fine modelling of the seven aircraft types based on a real scene by establishing an adaptive weighted conditional attention generative adversarial network and joint geospatial embedding (GE) network. An adaptive weighted conditional batch normalisation attention block solved the subclass entanglement by reassigning the intra-class-wise characteristic responses. Subsequently, an asymmetric residual self-attention module was developed by establishing a remote region asymmetric relationship for mining the finer potential spatial representation. The mapping relationship between the input RS scene and the potential space of the generated samples was explored through the GE network construction that used the selected prior distribution z, as an intermediate representation. A public RS dataset (OPT-Aircraft_V1.0) and two public datasets (MNIST and Fashion-MNIST) were used for simulation model testing. The results demonstrated the effectiveness of ATSS-1, promoting further development of realistic automatic RS simulation.

The unmanned aerial vehicle (UAV)-borne hyperspectral imaging system has the advantages of high spatial resolution, flexible operation, under-cloud flying, and easy cooperation with ground synchronous tests. Because this platform often flies under clouds, variations in solar illumination lead to irradiance inconsistency between different rows of hyperspectral images (HSIs). This inconsistency causes errors in radiation correction. In addition, due to the accuracy limitations of the GPS/inertial measurement unit (IMU) and irregular changes in flight platform speed and attitude, HSIs have deformation and drift, which is harmful to the geometric correction and stitching accuracy between flight strips. Consequently, radiation and geometric error limit further applications of large-scale hyperspectral data. To address the above problems, we proposed an integrated solution to acquire and correct UAV-borne hyperspectral images that consist of illumination data acquisition, radiance and geometric correction, HSI, multispectral image (MSI) registration, and multi-strip stitching. We presented an improved three-parameter empirical model based on the illumination correction factor, and it showed that the accuracy of radiation correction considering illumination variation improved, especially in some low signal-to-noise ratio (SNR) bands. In addition, the error of large-scale HSI stitching was controlled within one pixel.

Fourier transform imaging spectrometers (FTISs) are widely used in global hyperspectral remote sensing due to the advantages of high stability, high throughput, and high spectral resolution. Spectrum reconstruction (SpecR) is a classic problem of FTISs determining the acquired data quality and application potential. However, the state-of-the-art SpecR algorithms were restricted by the length of maximum optical path difference (MOPD) of FTISs and apodization processing, resulting in a decrease in spectral resolution; thus, the applications of FTISs were limited. In this study, a deep learning SpecR method, which directly learned an end-to-end mapping between the interference/spectrum information with limited MOPD and without apodization processing, was proposed. The mapping was represented as a fully connected U-Net (FCUN) that takes the interference fringes as the input and outputs the highly precise spectral curves. We trained the proposed FCUN model using the real spectra and simulated pulse spectra, as well as the corresponding simulated interference curves, and achieved good results. Additionally, the performance of the proposed FCUN on real interference and spectral datasets was explored. The FCUN could obtain similar spectral values compared with the state-of-the-art fast Fourier transform (FFT)-based method with only 150 and 200 points in the interferograms. The proposed method could be able to enhance the resolution of the reconstructed spectra in the case of insufficient MOPD. Moreover, the FCUN performed well in visual quality using noisy interferograms and gained nearly 70% to 80% relative improvement over FFT for the coefficient of mean relative error (MRE). All the results based on simulated and real satellite datasets showed that the reconstructed spectra of the FCUN were more consistent with the ideal spectrum compared with that of the traditional method, with higher PSNR and lower values of spectral angle (SA) and relative spectral quadratic error (RQE).

Under a dioxygen atmosphere, benzylphosphonates and related phosphoryl compounds can readily produce the corresponding trans-stilbenes in high yields with high selectivity upon treatment with bases. Various functional groups were tolerable under the reaction conditions. [ABSTRACT FROM AUTHOR]

A silver-free palladium-catalyzed dehydrogenative phosphorylation of terminal alkynes with hydrogen phosphine oxides has been developed. Both aromatic and aliphatic terminal alkynes including those bearing functional groups coupled readily with hydrogen phosphine oxides, producing the corresponding value-added alkynylphosphine oxides in good to excellent yields. This reaction could be easily conducted at gram scales (10 mmol) without any decrease of the reaction efficiency, showing highly potential synthetic value in organic synthesis. A plausible Pd(0)/Pd(II) mechanism is proposed. [ABSTRACT FROM AUTHOR]

A Pd-catalyzed dehydrogenative phosphorylation of thiols is developed. A variety of thiols dehydrogenatively couple readily with all three kinds of P(O)--H compounds, i.e., H-phosphonates, H-phosphinates, and secondary phosphine oxides, providing a general access to the valuable phosphorothioates including the P-chiral compounds. A plausible mechanism is proposed. [ABSTRACT FROM AUTHOR]

A simple and environmentally benign method was developed for the synthesis of chalcones in high to excellent yields by a phosphorous acid promoted alkyne-aldehyde hydration-condensation in an oil/water two-phase system. The method is the first efficient protocol for the preparation of chalcones that is mediated by a simple Brønsted acid in a two-phase system. [ABSTRACT FROM AUTHOR]

Themechanism of the palladium-catalyzed cross dehydrogenativecoupling of P(O)–H compounds with terminal alkynes was studied.Successive ligand-exchange reactions of Pd(OAc)2with ahydrogen phosphoryl compound and a terminal alkyne take place readilyto replace the two acetates on palladium, producing the corresponding(phosphoryl) (alkynyl)palladium complexes, which upon heating decomposedto the corresponding alkynylphosphorus compound. It is also confirmedthat in the stoichiometric reactions of the complexes, the configurationat phosphorus is retained. On the basis of these stoichiometric reactions,an efficient synthesis of P-chiral alkynylphosphorylcompounds via palladium-catalyzed stereoselective cross dehydrogenativecoupling of P-chiral P(O)–H compounds withterminal alkynes was developed. The key palladium complexes and thestereochemistry of the chiral phosphorus compounds are all unambiguouslydetermined by single-crystal X-ray analysis. [ABSTRACT FROM AUTHOR]

In this account, we summarize our recent work on the preparation of optically active H-phosphinates and their stereospecific transformations, including regio- and stereospecific additions, nucleophilic substitutions with organolithiums and Grignard reagents, halogenation with copper(II) chloride, and dehydrogenative couplings with heteroatom- hydrogen bonds. These reactions provide efficient ways for the synthesis of valuable, optically active, P-stereogenic, organophosphorus compounds from relatively easily prepared, enantiomerically pure, menthyl hydrogen phosphinates. The applications of optically active Hphosphinates in catalytic asymmetric hydrogenations are also discussed. 1 Optically Pure Menthyl Hydrogen Phosphinates: Easily Accessible P-Stereogenic Starting Materials 2 Optically Pure Menthyl Hydrogen Phosphinates as Starting Materials for the Synthesis of P-Chiral Compounds 2.1 Stereospecific Additions 2.1.1 Additions to Alkynes 2.1.2 Addition to Alkenes 2.1.3 Addition to p-Quinones 2.1.4 Additions to Ketones or Aldehydes 2.2 Stereospecific Nucleophilic Substitution by Organolithiums or Grignard Reagents 2.3 Stereospecific Halogenation with Copper(II) Chloride 2.4 Stereospecific Cross-Dehydrogenative Coupling with Nucleophiles (Amines, Alcohols, Thiols, etc.) 2.5 Stereospecific Cross-Coupling with C-X Bonds 3 Asymmetric Catalytic Hydrogenation Reactions with Optically Pure Menthyl Hydrogen Phosphinates as Ligands 4 Conclusion [ABSTRACT FROM AUTHOR]

The Ni-catalyzed direct C–H/C–Ocross couplings ofbenzylic alcohol derivatives with fluorobenzenes and heteroarenesare disclosed. This transformation provides a straightforward andefficient method for the synthesis of these valuable heteroatom-containingcompounds. [ABSTRACT FROM AUTHOR]

The first Ni-catalyzed C-O/P-H cross-coupling producing organophosphorus compounds is disclosed. This method features wide generality in regard to both C-O and P-H compounds: for C-O compounds, the readily available alcohol derivatives of aryl, alkenyl, benzyl, and allyl are applicable, and for P-H compounds, both >PV(O)H compounds (secondary phosphine oxide, H-phosphinate, and H-phosphonate) and hydrogen phosphines (>PIIIH) can be used as the substrates. Thus, a variety of valuable C(sp²)-P and C(sp³)-P compounds can be readily obtained in good to excellent yields by this new strategy. [ABSTRACT FROM AUTHOR]

A metal-free regioselective hydrobromination of alkynes has been developed to provide the Markovnikov-type vinyl bromides in good yields using dibromomethane/N,N-dimethylaniline as in-situ 'HBr' source. This protocol also represents an elegant example of the activation of sp² CH and CBr bonds in one pot, in which 'HBr' is generated and transferred under mild metal-free conditions. D-incorporated experiments were employed to investigate the reaction mechanism and a plausible reaction path was proposed. [ABSTRACT FROM AUTHOR]

A facile, highly stereo- and regioselective hydrometalation of alkynes generating alkenylmetal complex is disclosed for the first time from a reaction of alkyne, carboxylic acid, and a zerovalent group 10 transition metal complex M(PEt3)4 (M = Ni, Pd, Pt). A mechanistic study showed that the hydrometalation does not proceed via the reaction of alkyne with a hydridometal generated by the protonation of a carboxylic acid with Pt(PEt3)4, but proceeds via a reaction of an alkyne coordinate metal complex with the acid. This finding clarifies the long proposed reaction mechanism that operates via the generation of an alkenylpalladium intermediate and subsequent transformation of this complex in a variety of reactions catalyzed by a combination of Brφnsted acid and Pd(0) complex. This finding also leads to the disclosure of an unprecedented reduction of alkynes with formic acid that can selectively produce cis-, trans-alkenes and alkanes by slightly tuning the conditions. [ABSTRACT FROM AUTHOR]

For the first time, the long-proposed thermodynamically unstable catalytic intermediates alkenyl and aryl complexes sp²CPdH have been isolated through the reduction of the palladium acetates with hydrosilanes and subsequent stabilization of the hydridopalladiums with hydrosilanes. The structures of these hydridopalladiums were established by X-ray analysis. [ABSTRACT FROM AUTHOR]

Addition of P(O)H bonds to alkynes catalyzed by transition metals (Rh, Pd, and Ni) immobilized on polystyrene-bound triphenylphosphine proceeded efficiently to afford high yields of the addition products with high regioselectivity. The immobilized catalysts were easily recovered from the reaction mixture via simple centrifugal separation and could be reused several times without severe deactivation. [ABSTRACT FROM AUTHOR]