A 3-D scattering centre model-based SAR target recognition method using multi-level region matching

A 3-D scattering centre model-based synthetic aperture radar (SAR) automatic target recognition (ATR) method is proposed. Multi-level dominant scattering areas (DSAs) are generated from the test sample and model predicted target images, which can describe the target region and scattering centres distribution from coarse to fine. The DSA matching is conducted at each level using the morphological erosion operation and Euclidean distance transform. Finally, the energy of the region residuals is taken as the distance measure between the test sample and different target models so as to confirm the target label. The 3-D scattering centre model can provide very complete descriptions of the target. In addition, the designed distance measure comprehensively considers the possible nonlinear transformations between the model and test image using the morphological erosion operation and Euclidean distance transform. Experiments are performed on the electromagnetic (EM) simulated data of three military targets.</p

Manganese(I)-Catalyzed C–H 3,3-Difluoroallylation of Pyridones and Indoles

A novel and efficient C–H activation approach for the direct 3,3-difluoroallylation of 2-pyridones and indoles is herein reported using a manganese­(I) complex as the catalyst. A broad range of substrates with diverse functional groups were tolerated. Moreover, late-stage C–H functionalization of bioactive molecules was achieved in good yield

Meta-Selective C_Ar–H Nitration of Arenes through a Ru₃(CO)₁₂-Catalyzed Ortho-Metalation Strategy

The first example of transition metal-catalyzed meta-selective C_Ar–H nitration of arenes is described. With the use of Ru₃(CO)₁₂ as the catalyst and Cu­(NO₃)₂·3H₂O as the nitro source, a wide spectrum of arenes bearing diversified <i>N</i>-heterocycles or oximido as the directing groups were nitrated with meta-selectivity exclusively. Mechanism studies have demonstrated the formation of a new 18e-octahedral ruthenium species as a key <i>ortho</i>-C_Ar–H metalated intermediate, which may be responsible for the subsequent meta-selective electrophilic aromatic substitution (S_EAr). Moreover, this approach provides a fast-track strategy for atom/step economical synthesis of many useful pharmaceutical molecules

Meta-Selective C_Ar–H Nitration of Arenes through a Ru₃(CO)₁₂-Catalyzed Ortho-Metalation Strategy

The first example of transition metal-catalyzed meta-selective C_Ar–H nitration of arenes is described. With the use of Ru₃(CO)₁₂ as the catalyst and Cu­(NO₃)₂·3H₂O as the nitro source, a wide spectrum of arenes bearing diversified <i>N</i>-heterocycles or oximido as the directing groups were nitrated with meta-selectivity exclusively. Mechanism studies have demonstrated the formation of a new 18e-octahedral ruthenium species as a key <i>ortho</i>-C_Ar–H metalated intermediate, which may be responsible for the subsequent meta-selective electrophilic aromatic substitution (S_EAr). Moreover, this approach provides a fast-track strategy for atom/step economical synthesis of many useful pharmaceutical molecules

Integrative analysis of Mendelian randomization and gene expression profiles reveals a null causal relationship between adiponectin and diabetic retinopathy

Observational studies have been conducted to investigate the correlation between adiponectin and diabetic retinopathy (DR), but no consistent relationship has been established. In this study, we employed an integrative analysis that combined Mendelian randomization (MR) and bioinformatics analyses to comprehensively explore the association between DR and adiponectin, aiming to provide a unified answer of their relationship. Using the inverse-variance weighted (IVW) method, the odd ratio (OR) of developing DR per 1 mg/dL increment in genetically predicted log-transformed adiponectin concentration was estimated to be 0.949 (P = 0.557). Other robust MR methods produced consistent results, confirming the absence of a causal effect of adiponectin on DR. Additionally, the expression levels of the six adiponectin-related genes showed no significant differences among normal controls, individuals with diabetes but without DR, and those with DR Furthermore, the biological pathways enriched by these genes were not strongly relevant to DR. At both the individual gene and pathway levels, there were no overlaps between the adiponectin-related genes and the differentially expressed genes, indicating a lack of association between adiponectin and DR based on gene expression profiles. In summary, the integrative analysis, which combined MR and bioinformatics data mining, yielded compelling evidence supporting the notion that adiponectin is not a risk factor for DR.</p

Highly Stereoselective Assembly of Polycyclic Molecules from 1,6-Enynes Triggered by Rhodium(III)-Catalyzed C–H Activation

An Rh­(III)-catalyzed C–H activation of pyrazolones with 1,6-enynes was investigated. The regioselectivity of the C–H activation/alkyne insertion is readily solved by using symmetric enyne coupling partners, and a C–H activation-triggered cascade reaction is realized, which involves alkyne insertion, tautomerization, and double cyclization to offer a class of structurally complex polycyclic architectures. This cascade reaction tolerates a broad substrate scope in high regioselectivity and stereospecificity and furnishes three new chemical bonds and four chiral centers in a single operation. Various derivatizations of the polycyclic scaffolds are conducted, providing products with ample space for further functional transformations

Fabrication of Structurally-Colored Fibers with Axial Core–Shell Structure via Electrophoretic Deposition and Their Optical Properties

Structurally colored fibers were fabricated using different-sized polystyrene (PS) nanospheres via electrophoretic deposition on conductive carbon fiber surfaces. The reflective spectra corresponding to different colors were taken by microzone and angle-resolved spectrometers from a single colloidal fiber. As confirmed by structural analysis, the outer layer of the core–shell colloidal fibers consisted of face-centered cubic (f.c.c.) domains without long-range order. It is revealed that the absence of long-range order in the colloidal assembly caused isotropic reflection in radial and longitudinal directions on the colloidal fibers. Furthermore, due to the incorporation of random defects during growth process, the experimental spectra are blue-shifted and broad compared to reflective spectra calculations based on the curved f.c.c. structure. This technique is speculated to have potential application in structural coloration and radiation-proof fabrics

Ru(II)-Catalyzed Direct C(sp²)–H Activation/Selenylation of Arenes with Selenyl Chlorides

A new ruthenium catalytic system was developed for the construction of a C­(sp²)–Se bond with the assistance of directing groups. This protocol features mild reaction conditions, wider substrate scope, and convenient late-stage selenylation of bioactive molecules

Cu-Mediated Sulfonyl Radical-Enabled 5-<i>exo-trig</i> Cyclization of Alkenyl Aldehydes: Access to Sulfonylmethyl 1<i>H</i>‑Indenes

An efficient method for the construction of sulfonylmethyl 1<i>H</i>-indenes via Cu­(I)-mediated sulfonyl radical-enabled 5-<i>exo-trig</i> cyclization of alkenyl aldehydes has been developed for the first time. Mechanistic studies indicated that a radical addition–cyclization–elimination (RACE) process might be involved. The reaction features a relatively broad substrate scope, good annulation efficiency, and varying functional group tolerance

Cobalt-Catalyzed Carbonylation of C(sp²)–H Bonds with Azodicarboxylate as the Carbonyl Source

A novel and efficient approach for the C­(sp²)–H bond carbonylation of benzamides has been developed using stable and inexpensive Co­(OAc)₂·4H₂O as the catalyst and the commercially available and easily handling azodicarboxylates as the nontoxic carbonyl source. A broad range of substrates bearing diverse functional groups were tolerated. This is the first example where cobalt-catalyzed C­(sp²)–H bond carbonylation occurs with azodicarboxylate as the carbonyl source