Dissociation of regional activity in the default mode network in first-episode,drug-naive major depressive disorder at rest

Background

Major depressive disorder (MDD) is associated with altered neural activity in the default mode network (DMN). In the present study, we used a fractional amplitude of low-frequency fluctuations (fALFF) approach to directly investigate the features of spontaneous brain activity of the DMN in patients with the first-episode, drug-naive MDD at rest.

Methods

Twenty-four first-episode, drug-naive patients with MDD and 24 age-, gender-, and education-matched healthy subjects participated in the study. The fALFF and independent component analysis (ICA) approaches were utilized to analyze the data.

Results

Patients with MDD exhibited a dissociation pattern of resting-state fALFF in the DMN, with increased fALFF in the left dorsal medial prefrontal cortex (MPFC) and decreased fALFF in the left parahippocampal gyrus (PHG). The increased fALFF values of the left dorsal MPFC were positively correlated to the Hamilton Rating Scale for Depression (HRSD) scores.

Conclusions

Our results first suggested that there was a dissociation pattern of resting-state fALFF in the DMN in patient with MDD, which highlighted the importance of the DMN in the pathogenesis of MDD.     

Coexistence of Co doping and strain on arsenene and antimonene: tunable magnetism and half-metallic behavior

Effectively modulating the magnetism of two-dimensional (2D) systems is critical for the application of magnetic nanostructures in quantum information devices. In this work, by employing density functional theory calculations, we found the coexistence of Co doping and strain can effectively control the spin states of arsenene and antimonene structures. Unstrained Co-doped arsenene (arsenene–Co) and Co-doped antimonene (antimonene–Co) structures are nonmagnetic while under a strain, the magnetic moments of both cases were abruptly increased to about 2 μ_B. The emergence of magnetism can be reflected by the reduction of the interactions between Co and its neighboring atoms by the strain, which leads to the spin-splitting of Co-3d states. More importantly, we found that the transition of magnetism accompanies the modifications of the electronic properties of arsenene and antimonene so that under strain both structures can exhibit a novel half-metallic behavior. These results provide an effective pathway for the development of arsenene- and antimonene-based electronic devices by applying Co doping and strain.

Effectively modulating the magnetism of two-dimensional (2D) systems is critical for the application of magnetic nanostructures in quantum information devices.     

High-efficiency and stable piezo-phototronic organic perovskite solar cell

Perovskite materials are regarded as next-generation organic photovoltaic (OPV) materials due to their excellent physical and chemical properties. Recent theoretical and experimental advances also revealed the piezoelectric properties of CH₃NH₃PbI₃ perovskite thin films. In this work, a CH₃NH₃PbI₃ perovskite piezo-phototronic solar cell is studied in theory. The output parameters such as open circuit voltage, current–voltage characteristics, fill factor, power conversion efficiency, and maximum output power with external strains are presented. The coefficient to characterize piezo-phototronic modulation is also calculated for the piezo-phototronic solar cell. With the change of strain, the output performance can be controlled and enhanced. This principle can offer not only a novel and unique approach to produce high-performance, stable perovskite solar cells, but also a principle to design new piezoelectric perovskite optoelectronic devices.

Enhancing the performance of perovskite solar cells with strain based on a piezo-phototronic effect.     

Gaussian source model based iterative algorithm for EEG source imaging

Estimation of the neural active sources from the scalp electroencephalogram (EEG) is an ill-posed inverse problem. In this paper, we propose a new source model: Gaussian distributed Source Model (GSM), to model the activations in brain. GSM may imitate an Isolated Source Model (ISM) or a Distributed Source Model (DSM) by adopting different supporting range parameter of the Gaussian function. Using GSM, an iterative Gaussian source Imaging Algorithm (GIA) is developed to detect the EEG sources. As GIA dynamically reduces the solution space, the solution may gradually converge to a desired distribution. A comparative evaluation among LORETA, FOCUSS and GIA was conducted for both isolated point sources and distributed sources, the results demonstrate that GIA is more flexible and efficient for various actual sources configurations. Finally, GSM was applied to real recordings obtained from a visual spatial attention task; the corresponding source activation areas of the early component are localized in contralateral occipital cortices, consistent with the retinotopic organization of early visual spatial attention effects.     

Theoretical investigations of the Jahn–Teller distortions for V and Cr in α-Al2O3

The spin Hamiltonian parameters (zero-field splittings D, g factors g_// and g_⊥, the hyperfine structure constants and the spin–lattice coupling coefficients |G_–|, |G₁₅|, |G₅₁| and |G₄₄|) for V³⁺ and Cr⁴⁺ in α-Al₂O₃ are theoretically investigated from the perturbation formulas of these parameters for a 3d² ion under trigonally distorted octahedra. In these formulas, the contributions from the dynamical Jahn–Teller effect, the configuration interactions and the ligand orbital and spin–orbit coupling interactions are quantitatively taken into account in a uniform way based on the ligand field model. The impurity-ligand bond angles related to the C₃ axis are found to experience the variations of about 1.5–1.9° due to the dynamical Jahn–Teller nature, yielding more regular octahedra around the 3d² impurities. In addition, the size mismatching substitution of the smaller host Al³⁺ by the larger impurities may also bring forward some contributions to the local angular distortions. All the calculated spin Hamiltonian parameters based on the above angular variations show reasonable agreement with the experimental data for both centers. The improvements are achieved in this work by adopting the uniform model and formulas and much fewer adjustable parameters as compared with the previous treatments.     

Synthesis and Properties of Novel Thermoresponsive Polyesters with Oligo(ethylene glycol) Pendent Chains

A new class of thermoresponsive polyesters is prepared by alternating ring‐opening copolymerization of succinic anhydride (SA) and epoxide bearing oligo(ethylene glycol) (oligo‐EG) pendant chains with the number of repeat ethylene glycol unit ranging from 1 to 3. The copolymerization kinetics and their various properties are investigated in detail. The increase of oligo‐EG length leads to a significant shift of the thermoresponsive transition to higher temperature. The copolymers hydrolyzed with unusual chain end cleavage mode and base acceleration feature. And the copolymers and their degradation products had no acute toxicities. The reported thermoresponsive polyesters are highly useful materials for in vivo biomedical applications.     

Fluorination of electrospun hydrogel fibers for a controlled release drug delivery system

Electrospinning and fluorination were carried out in order to obtain a controlled release drug delivery system to solve the problem of both an initial burst of the drug and a limited release time. Poly(vinyl alcohol) was electrospun with Procion Blue as a model drug and heat treated in order to obtain cross-linked hydrogel fibers. Two different kinds of electrospun fibers of thin and thick diameters were obtained by controlling the electrospinning conditions. Thin fibers offer more available sites than thick fibers for surface modification during fluorination. Fluorination was conducted to control the release period by introducing hydrophobic functional groups on the surface of fibers. With an increase in the reaction pressure of the fluorine gas hydrophobic C–F and C–F₂ bonds were more effectively introduced. Over-fluorination of the fibers at higher reaction pressures of fluorine gas led to the introduction of C–F₂ bonds, which made the surface of the fibers hydrophobic and resulted in a decrease in their swelling potential. When C–F bonds were generated the initial drug burst decreased dramatically and total release time increased significantly, by a factor of approximately 6.7 times.     

一种基于独立成分分析的功能磁共振数据处理方法

独立成分分析（ICA）是统计信号处理中的一项新技术，用来从混合信号的多维观测中提取具有统计独立性的成分。我们针对功能磁共振数据处理，采用先对相邻的两体元信号作ICA分离，然后与参考信号进行相关，把相关系数大于一定阈值的体元作为刺激引起兴奋的体元，从而实现刺激的功能定位。经实际脑功能磁共振数据试验，初步证明了方法的有效性。     

Systematic analysis and prediction of longevity genes in Caenorhabditis elegans

An important task of aging research is to find genes that regulate lifespan. However, identification of genes related to longevity (referred to as longevity genes hereafter) through web-lab experiments such as genetic screens is a tedious and labor-intensive activity. Developing an algorithm to predict longevity genes should facilitate aging research. In this paper, we systematically analyzed properties of longevity genes in Caenorhabditis elegans and found that, when compared to genes not yet known to be involved in longevity, known longevity genes display the following features: (i) longer genomic sequences and protein sequences, (ii) a stronger tendency to co-express with other genes during a transition from dauer state (an extremely long lifespan) to non-dauer state (a normal lifespan), (iii) significant enrichment in certain functions and RNAi phenotypes, (iv) higher sequence conservation, and (v) higher in several network topological features such as degrees in a functional interaction network. Based on these features, we developed an algorithm to predict longevity genes in C. elegans and obtained 243 novel longevity genes with a precision rate of 0.85. Some of the predicted genes have been validated by published articles or wet lab experiments. The contribution of each feature to the predicted results was also evaluated.