Yanshan University

About: Yanshan University is a education organization based out in Qinhuangdao, China. It is known for research contribution in the topics: Microstructure & Control theory. The organization has 19544 authors who have published 16904 publications receiving 184378 citations. The organization is also known as: Yānshān dàxué.

Redox properties of undoped 5 nm diamond nanoparticles

Abstract: This paper demonstrates the promoting effects of 5 nm undoped detonation diamond nanoparticles on redox reactions in solution. An enhancement in faradaic current for the redox couples Ru(NH3)63+/2+ and Fe(CN)64–/3– was observed for a gold electrode modified with a drop-coated layer of nanodiamond (ND), in comparison to the bare gold electrode. The ND layer was also found to promote oxygen reduction. Surface modification of the ND powders by heating in air or in a hydrogen flow resulted in oxygenated and hydrogenated forms of the ND, respectively. Oxygenated ND was found to exhibit the greatest electrochemical activity and hydrogenated ND the least. Differential pulse voltammetry of electrode-immobilised ND layers in the absence of solution redox species revealed oxidation and reduction peaks that could be attributed to direct electron transfer (ET) reactions of the ND particles themselves. It is hypothesised that ND consists of an insulating sp3diamond core with a surface that has significant delocalised π character due to unsatisfied surface atoms and CO bond formation. At the nanoscale surface properties of the particles dominate over those of the bulk, allowing ET to occur between these essentially insulating particles and a redox species in solution or an underlying electrode. We speculate that reversible reduction of the ND may occur via electron injection into available surface states at well-defined reduction potentials and allow the ND particles to act as a source and sink of electrons for the promotion of solution redox reactions.

Effect of Lycium barbarum polysaccharide on the improvement of insulin resistance in NIDDM rats.

Abstract: Lycium barbarum is one of the traditional oriental medicines. It has been reported to reduce blood glucose levels. In this study, the effect of Lycium barbarum polysaccharide (LBP) on the improvement of insulin resistance and lipid profile was studied in rats, a model for non-insulin dependent diabetes mellitus (NIDDM). The rats were divided into three groups: control, NIDDM control, and NIDDM+LBP. Diabetes model groups were made by feeding high-fat diet and subjecting to i.p. streptozotocin (50 mg/kg). LBP treatment for 3 weeks resulted in a significant decrease in the concentration of plasma triglyceride and weight in NIDDM rats. Furthermore, LBP markedly decreased the plasma cholesterol levels and fasting plasma insulin levels, and the postprandial glucose level at 30 min during oral glucose tolerance test and significantly increased the Insulin Sensitive Index in NIDDM rats. In the present study, we have tested that LBP can alleviate insulin resistance and the effect of LBP is associated with increasing cell-surface level of glucose transporter 4 (GLUT4) in skeletal muscle of NIDDM rats. Under insulin stimulus, GLUT4 content in plasma membrane in NIDDM control rats was significantly lower than that of control (p<0.01), and GLUT4 content in the plasma membrane in NIDDM+LBP rats was higher than that of NIDDM control rats (p<0.01). In conclusion, LBP can ameliorate insulin resistance, and the mechanism may be involved in increasing cell-surface level of GLUT4, improving GLUT4 trafficking and intracellular insulin signaling.

A new near infrared photosensitizing nanoplatform containing blue-emitting up-conversion nanoparticles and hypocrellin A for photodynamic therapy of cancer cells

Abstract: The utilization of up-conversion nanoparticles (UCNPs) for photodynamic therapy (PDT) has gained significant interest due to their unique ability to convert near infrared light to UV/visible light. Previous work mainly focused on the fabrication of green and red emitting UCNPs to load photosensitizers (PSs) for PDT. In this work, we firstly developed a new multifunctional nanoplatform combining blue-emitting UCNPs with blue-light excited PS (hypocrellin A, HA) as a NIR photosensitizing nanoplatform for PDT of cancer cells. Tween 20 coated NaYbF4:Tm, Gd@NaGdF4 UCNPs (Tween 20-UCNPs) with strong blue up-conversion luminescence and good water dispersibility were prepared for use as PS carriers. The blue emission band matched well with the efficient absorption band of HA, thereby facilitating the resonance energy transfer from UCNPs to HA and then activating HA to produce singlet oxygen (1O2). The in vitro study showed that these Tween 20-UCNPs@HA complexes could efficiently produce 1O2 to kill cancer cells under 980 nm NIR excitation. Moreover, these Gd3+ and Yb3+ containing nanoparticles also exhibited positive contrast effects in both T1 weighted magnetic resonance imaging (MRI) and computed tomography (CT) imaging, making them become a multifunctional platform for simultaneous PDT and bio-imaging.

Compressed carbon nanotubes: A family of new multifunctional carbon allotropes

Abstract: The exploration of novel functional carbon polymorphs is an enduring topic of scientific investigations. In this paper, we present simulations demonstrating metastable carbon phases as the result of pressure induced carbon nanotube polymerization. The configuration, bonding, electronic, and mechanical characteristics of carbon polymers strongly depend on the imposed hydrostatic/non-hydrostatic pressure, as well as on the geometry of the raw carbon nanotubes including diameter, chirality, stacking manner, and wall number. Especially, transition processes under hydrostatic/non-hydrostatic pressure are investigated, revealing unexpectedly low transition barriers and demonstrating sp(2)→sp(3) bonding changes as well as peculiar oscillations of electronic property (e.g., semiconducting→metallic→semiconducting transitions). These polymerized nanotubes show versatile and superior physical properties, such as superhardness, high tensile strength and ductility, and tunable electronic properties (semiconducting or metallic).