A joint shape evolution approach to medical image segmentation using expectation-maximization algorithm

This study proposes an expectation–maximization (EM)-based curve evolution algorithm for segmentation of magnetic resonance brain images. In the proposed algorithm, the evolution curve is constrained not only by a shape-based statistical model but also by a hidden variable model from image observation. The hidden variable model herein is defined by the local voxel labeling, which is unknown and estimated by the expected likelihood function derived from the image data and prior anatomical knowledge. In the M-step, the shapes of the structures are estimated jointly by encoding the hidden variable model and the statistical prior model obtained from the training stage. In the E-step, the expected observation likelihood and the prior distribution of the hidden variables are estimated. In experiments, the proposed automatic segmentation algorithm is applied to multiple gray nuclei structures such as caudate, putamens and thalamus of three-dimensional magnetic resonance imaging in volunteers and patients. As for the robustness and accuracy of the segmentation algorithm, the results of the proposed EM-joint shape-based algorithm outperformed those obtained using the statistical shape model-based techniques in the same framework and a current state-of-the-art region competition level set method.     

Memory Effects in High-Dimensional Systems Faithfully Identified by Hilbert–Schmidt Speed-Based Witness

A witness of non-Markovianity based on the Hilbert–Schmidt speed (HSS), a special type of quantum statistical speed, has been recently introduced for low-dimensional quantum systems. Such a non-Markovianity witness is particularly useful, being easily computable since no diagonalization of the system density matrix is required. We investigate the sensitivity of this HSS-based witness to detect non-Markovianity in various high-dimensional and multipartite open quantum systems with finite Hilbert spaces. We find that the time behaviors of the HSS-based witness are always in agreement with those of quantum negativity or quantum correlation measure. These results show that the HSS-based witness is a faithful identifier of the memory effects appearing in the quantum evolution of a high-dimensional system with a finite Hilbert space.     

Sono-chemical synthesis and characterization of Fe3O4@mTiO2-GO nanocarriers for dual-targeted colon drug delivery

Research on Chemical Intermediates - In this study, a kind of magnetic Fe3O4@mTiO2-GO (where m was shorted mesoporous) hybrids with core–shell nano-structure for controlled dual targeted drug...     

Regioselective synthesis of novel spiroindane-1,3-diones through 1,3-dipolar cycloaddition reactions

A facile synthesis of novel spiroindane-1,3-diones has been achieved via 1,3-dipolar cycloaddition of an azomethine ylide, generated in situ from ninhydrin and 1,2,3,4-tetrahydroisoquinoline, with the conjugated double bond of chalcone derivatives. The regiochemistry and structures of the cycloadducts were determined with spectroscopic data and by X-ray crystal structure analysis.     

Evaluation of the mechanism,regio-, and diastereoselectivity of aza-Diels–Alder reactions of 2H-azirine under a Lewis acid catalyst

Structural Chemistry - The molecular mechanism of the cycloaddition reactions of 2H-azirine with 1-methoxybutadiene and cyclohexadiene has been studied at the M06-2X/cc-pVDZ level of theory....     

Palladium catalyzed mild reduction of α,β-unsaturated compounds by triethylsilane

The palladium(II) chloride/triethylsilane system has been successfully applied for the selective hydrogenation of the carbon-carbon double bond of α,β-unsaturated ketones to yield the corresponding saturated carbonyl compounds. The reaction takes place under mild conditions and affords high yields.     

Novel (4-oxothiazolidine-2-ylidene)benzamide derivatives: synthesis,characterization and crystal structures

Research on Chemical Intermediates - A convenient, one-pot, multicomponent synthesis of new (4-oxothiazolidine-2-ylidene)benzamide derivatives by unsymmetrical thioureas, various amines and methyl...     

Copper Schiff base complex immobilized on magnetic graphene oxide: Efficient heterogeneous nanocatalyst for treating environmental pollutants and synthesis of chromenes

Herein, a new Cu(II) Schiff base complex was immobilized onto the magnetic graphene oxide surface through a stepwise procedure. The as-synthesized nanostructure (GO/Fe₃O₄/CuL) was characterized by various techniques including Fourier transform infrared (FT-IR), Raman spectroscopies, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), energy-dispersive X-ray (EDX) and inductively coupled plasma (ICP) spectroscopies, N₂ adsorption–desorption analysis, vibrating sample magnetometry (VSM), and X-ray diffraction (XRD). The catalytic activity of the synthesized nanocatalyst was examined in 4-nitrophenol (4-NP), Congo red (CR), and methylene blue (MB) reduction using NaBH₄ in an aqueous solution at room temperature. The reaction progress was monitored by UV–Vis spectroscopy. Also, the synthesized nanostructure was evaluated as an efficient catalyst for the synthesis of 2-amino-4H-benzopyrans via three-component reactions of 1-naphthol, malononitrile, and various aldehydes in ethanol/water at 50°C. The use of green solvents, the short reaction time, the high product yield, and easy separation from the reaction environment are the main benefits of this catalytic system. By covalent grafting of the complex on the graphene oxide surface, its catalytic performance significantly increased compared with graphene oxide; this is probably related to the chemical change of the graphene oxide surface. The results show the high chemical stability and the improved reusability of the synthesized nanocatalyst (six times) without significant loss in the catalytic activity of GO/Fe₃O₄/CuL nanocomposite.