Time filter

Source Type

Li W.,China University of Mining and Technology | Li W.,Shandong Energy Group Co. | Yang R.S.,China University of Mining and Technology
Advanced Materials Research | Year: 2014

Loose blasting technology is applied to the problem of fully mechanized coal face passing through fault. The paper gets safe and practical loose blasting parameters and blasting process, achieves no re-open-off cut for the fully mechanized coal face, reduces loss of coal pillars for faults and improves the coal recovery rate. At last, the goal of high yield, steady yield, and increasing yield for fully mechanized mining face is realized. © (2014) Trans Tech Publications, Switzerland.

Wang G.,Shandong Energy Group Co. | Wang G.,Shandong University | Qiu J.,Shandong University | Zheng L.,Shandong University | And 4 more authors.
Journal of Biomaterials Science, Polymer Edition | Year: 2014

The surface characteristics of biomaterials, especially regarding the sustained delivery of bone morphogenetic protein-2 (BMP-2), can possibly provide a novel and effective drug delivery system that can enhance osteogenesis. In this study, we evaluated the BMP-2 adsorption and release ability of the surface biomimetic hydroxyapatite (HAp) nanostructure on a new HAp-coated genipin-chitosan conjugation scaffold (HGCCS), and the resulting osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. HGCCS exhibited a loading efficiency of 65% (1.30 g), which is significantly higher than 28% (0.56 g, p < 0.01) for the genipin cross-linked chitosan framework, as quantified by an enzyme-linked immunosorbent assay. More importantly, we found that the release of BMP-2 from HGGCS sustained for at least 14 days in simulated body fluid in vitro, which is much better than the burst release within 3 days for CGF. Moreover, the BMP-2 release from HGCCS induced an increase in alkaline phosphatase activity as an indicator of osteogenic differentiation of seeded BMSCs for 14 days in vitro. HGCCS also stimulated a high mRNA expression of osteogenic differentiation makers, runt-related transcription factor 2 for 14 days, osteopontin for 3 days, and osteocalcin for 14 days. The results of this study suggest that the surface biomimetic HAp nanostructure of HGCCS used as a delivery system for BMP-2 is capable of promoting osteogenic differentiation in vitro. These findings demonstrated that HAp nanostructure assembled on organic porous scaffold could work as both calcium source and absorption/release platform, which opened a new research avenue for cell growth factor release, and provided a promising strategy for design and preparation of bioactive scaffold for bone tissue engineering. © 2014 © 2014 Taylor & Francis.

Zheng T.,North China Electrical Power University | Chen P.,North China Electrical Power University | Mao A.,China Electric Power Research Institute | Xu Z.,Shandong Energy Group Co. | Liu L.,North China Electrical Power University
Dianwang Jishu/Power System Technology | Year: 2014

There is a close relation between the saturation characteristic of current transformer (CT) and the performance of protective relayings. In regional power grid the geomagnetically induced current (GIC) possesses the feature of high-amplitude, low-frequency, time-variance and so on, its impact on saturation characteristic of CT is not so identical with the impacts of through-current due to external fault, non-periodic component in inrush current and DC magnetic biasing caused by HVDC power transmission, so it is worthy of attention. Based on typical waveform feature of GIC an equivalent source model of GIC is constructed, and using PSCAD/EMTDC the saturation characteristic of CT under the affect of GIC is simulated, and the resulting affect on transformer differential protection is researched. Research result shows that GIC may lead to serious saturation of CT's magnetic path and it makes the waveform distortion characteristic in the current at CT's secondary side disappeared, so the unbalanced current calculated by transformer differential protection is enlarged and the content of the second order harmonic in the differential current will drop below the restraint threshold, and finally the malfunction of transformer differential protection occurs. To prevent such a malfunction, the measure based on differential current and the variation tendency of the content of second order harmonic in it can be adopted.

Guo X.,China University of Mining and Technology | Guo X.,Shandong Energy Group Co. | Liu J.,North China Institute of Science and Technology | Jiang F.,University of Science and Technology Beijing
Caikuang yu Anquan Gongcheng Xuebao/Journal of Mining and Safety Engineering | Year: 2015

By using the in-situ observation and numerical simulation, the roof moving features of fully-mechanized sublevel caving face with deep alluvium has been studied. The results can be drawn as follows: 1) The time effect of the load of supports in the fully mechanized caving face with deep alluvium is significant. 2) While with advance of working face, the break of the immediate roof forms "rock-gangue" structure periodically and the break of the basic roof induces weighting of working face. 3) The weighting order along incline direction of the working face follows roof fracture characteristics of general working face. 4) The area of overlying strata area to be controlled by supports is large, and the strength of weighting induced by the upper basic roof breaking is large. 5) The advance stress fluctuation monitoring technology offers a new method for weighting prediction in working face. Finally, the suggestion about roof accident prevention of fully-mechanized sublevel caving face with deep alluvium was proposed. The study results can be useful for roof control design and roof accidents prevention in fully-mechanized sublevel caving face with deep alluvium. ©, 2015, China University of Mining and Technology. All right reserved.

Qiu J.,Shandong University | Li J.,Shandong University | Wang G.,Shandong Energy Group Co. | Zheng L.,Shandong University | And 5 more authors.
ACS Applied Materials and Interfaces | Year: 2013

As a biocompatible and bioactive natural tissue engineering scaffold, porcine acellular dermal matrix (PADM) has limitations for the application in tissue regeneration due to its low strength and rapid biodegradation. Here, purified PADM was modified by a nontoxic cross-linker (genipin) to enhance its mechanical properties and improve its resistance to enzymatic degradation. In vitro testing results demonstrated that the stiffness of the genipin cross-linked PADM was improved and biodegradation rate was decreased. Results of cell proliferation assays showed that the cross-linking reaction by genipin did not undermine the cytocompatibility of PADM. Furthermore, genipin cross-linking imparted an observable fluorescence allowing visualization of the scaffold's three-dimensional (3D) porous structure and cell distribution by confocal laser scanning microscopy (CLSM). Immunostaining of the cell nuclei and cytoskeleton indicated that MC3T3-E1 preosteoblasts were tightly adhered to and uniformly distributed onto the cross-linked PADM scaffold. Results of this study suggest that the 3D porous genipin cross-linked PADM with intrinsic fluorescence may have broader applications for tissue engineering scaffolds where higher mechanical stiffness is needed. © 2012 American Chemical Society.

Discover hidden collaborations