Northeastern University (China)

About: Northeastern University (China) is a education organization based out in Shenyang, China. It is known for research contribution in the topics: Control theory & Microstructure. The organization has 36087 authors who have published 36125 publications receiving 426807 citations. The organization is also known as: Dōngběi Dàxué & Northeastern University (东北大学).

Green preparation of nitrogen-doped carbon dots derived from silkworm chrysalis for cell imaging

Abstract: Carbon dots (CDs) with a high quantum yield have been synthesized by a facile and green one-pot approach under microwaves with silkworm chrysalis (SC) as the natural carbon source, without using any other chemicals/reagents. The morphology and optical properties of the resultant CDs are characterized by TEM, XRD, FT-IR, XPS, UV-vis and photoluminescence (PL). The SC-CDs have an average size of 19 nm, and contain C, O and N with relative contents of ca. 71.32%, 22.96% and 5.72%, respectively. A significant emission at 420 nm at an excitation wavelength of 350 nm is recorded, resulting in a quantum yield of 46% with quinine sulfate (quantum yield 54%) as a reference. In addition to excellent solubility and stability in aqueous medium, the SC-CDs exhibit excitation-dependent photoluminescence with a large Stokes shift of 70 nm. It is further demonstrated that the SC-CDs exhibit a low cytotoxicity at a higher concentration of 15 mg mL−1 and they are able to display bright blue, green and red colors under an inverted fluorescence microscope during cell imaging experiments, showing their vast potential in bioimaging.

Fuzzy Filter Design for Nonlinear Systems in Finite-Frequency Domain

Abstract: This paper is concerned with the problem of fuzzy-filter design for discrete-time nonlinear systems in the Takagi-Sugeno (T-S) form. Different from existing fuzzy filters, the proposed ones are designed in finite-frequency domain. First, a so-called finite-frequency l2 gain is defined that extends the standard l2 gain. Then, a sufficient condition for the filtering-error system with a finite-frequency l2 gain is derived. Based on the obtained condition, three fuzzy filters are designed to deal with noises in the low-, middle-, and high-frequency domain, respectively. The proposed fuzzy-filtering method can get a better noise-attenuation performance when frequency ranges of noises are known beforehand. An example about a tunnel-diode circuit is given to illustrate its effectiveness.

Fault-Tolerant Controller Design for General Polynomial-Fuzzy-Model-Based Systems

Abstract: This paper studies the fault-tolerant control problem for a class of nonlinear systems based on polynomial fuzzy model. A typical actuator fault model is presented to describe the loss of effectiveness fault in a multimode framework. The considered polynomial-fuzzy-model-based systems are more general, since the assumption that the input matrix $\mathbf {B}_{i}(\mathbf {x}),i=1,\ldots, p$ has at least one zero row, is not required any more. A polynomial Lyapunov function candidate depending on any system state is applied to design the fault-tolerant controller, in which the number of rules and membership functions can be matched or mismatched with polynomial fuzzy model. To deal with nonconvex problem, some nonlinear terms are successfully described as an index to be optimized to zero by a semidefinite programming. Compared with some published works, the resultant sum of squares based design conditions are with less computation complexity and potentially more relaxed. Using the third-party MATLAB toolbox SOSTOOLS, simulation examples are given to illustrate the effectiveness of the new method.

Comparison of amorphous, pseudohexagonal and orthorhombic Nb2O5 for high-rate lithium ion insertion

Abstract: Amorphous, pseudohexagonal and orthorhombic Nb2O5 nanoparticles were synthesized using a facile and green sol–gel process followed by thermal treatment at 450 °C, 600 °C and 800 °C for 3 h in air, respectively. The resulting materials have been subjected to a detailed experimental study and comparison of their structural, electrical and electrochemical properties. The experiments have demonstrated that the pseudohexagonal Nb2O5 (TT-Nb2O5) exhibited higher storage capacity, largely due to its high specific surface area and small crystallites, and better cycling performance than both amorphous Nb2O5 (a-Nb2O5) and orthorhombic Nb2O5 (T-Nb2O5); such experimental findings were found to be associated with and thus ascribed to the lower charge transfer resistance and higher lithium ion diffusion coefficient of TT-Nb2O5 than those of a-Nb2O5 and T-Nb2O5. This research contributes to a better fundamental understanding of the relationship between the crystal structure and the crystallinity and electrochemical properties, particularly Li-ion storage properties, and leads to a possible new advancement in the research field of lithium ion batteries and pseudocapacitors.