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Search Results: 1 - 10 of 104175 matches for " Jiqiang Zhang "
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Scattering theory for nonlinear Schroedinger equations with inverse-square potential
Junyong Zhang,Jiqiang Zheng
Mathematics , 2013,
Abstract: We study the long-time behavior of solutions to nonlinear Schroedinger equations with some critical rough potential of inverse square type. The new ingredients are the interaction Morawetz-type inequalities and Sobolev norm property associated with the Lapalacian with inverse square potential. We use such properties to obtain the scattering theory for the defocusing energy-subcritical nonlinear Schroedinger equation with inverse square potential in energy space.
In Vitro Corrosion and Bioactivity Study of Surface Phytic Acid Modified AZ31 Magnesium Alloy  [PDF]
Xu Yang, Lanlan Li, Jian He, Haiying Guo, Jiqiang Zhang
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.52009

The purpose of the present work was to examine in vitro corrosion and bioactivity of surface phytic acid treatment AZ31 magnesium alloys. Untreated AZ31 magnesium alloys were used as control. The surface morphologies of magnesium alloys were observed by SEM. EDS was used to analyze the surface chemical elemental compositions and elemental concentration distribution. Corrosion properties were evaluated by electrochemical tests. Human osteosarcoma MG-63 cells were used to examine cell viability and proliferation. The results showed that surface phytic acid treatment resulted in a surface coating formation, which did not significantly improve the corrosion resistance of the alloys. The corrosion potential of AZ31 magnesium alloy positive shifted only about 0.04 V (from -1.50 V to -1.46 V); and the corrosion current decreased only 0.354 mA/cm2 (from 2.547 × 10-3 mA/cm2 to 2.193 × 10-3 mA/cm

The Defocusing Energy-Critical Wave Equation with a Cubic Convolution
Changxing Miao,Junyong Zhang,Jiqiang Zheng
Mathematics , 2012,
Abstract: In this paper, we study the theory of the global well-posedness and scattering for the energy-critical wave equation with a cubic convolution nonlinearity $u_{tt}-\Delta u+(|x|^{-4}\ast|u|^2)u=0$ in spatial dimension $d \geq 5$. The main difficulties are the absence of the classical finite speed of propagation (i.e. the monotonic local energy estimate on the light cone), which is a fundamental property to show the global well-posedness and then to obtain scattering for the wave equations with the local nonlinearity $u_{tt}-\Delta u+|u|^\frac4{d-2}u=0$. To compensate it, we resort to the extended causality and utilize the strategy derived from concentration compactness ideas. Then, the proof of the global well-posedness and scattering is reduced to show the nonexistence of the three enemies: finite time blowup; soliton-like solutions and low-to-high cascade. We will utilize the Morawetz estimate, the extended causality and the potential energy concentration to preclude the above three enemies.
Strichartz estimates for wave equation with inverse square potential
Changxing Miao,Junyong Zhang,Jiqiang Zheng
Mathematics , 2013, DOI: 10.1142/S0219199713500260
Abstract: In this paper, we study the Strichartz-type estimates of the solution for the linear wave equation with inverse square potential. Assuming the initial data possesses additional angular regularity, especially the radial initial data, the range of admissible pairs is improved. As an application, we show the global well-posedness of the semi-linear wave equation with inverse-square potential $\partial_t^2 u-\Delta u+\frac{a}{|x|^2}u=\pm|u|^{p-1}u$ for power $p$ being in some regime when the initial data are radial. This result extends the well-posedness result in Planchon, Stalker, and Tahvildar-Zadeh.
Scattering theory for the radial $\dot H^{1/2}$-critical wave Equation with a cubic convolution
Changxing Miao,Junyong Zhang,Jiqiang Zheng
Mathematics , 2015, DOI: 10.1016/j.jde.2015.08.020
Abstract: In this paper, we study the global well-posedness and scattering for the wave equation with a cubic convolution $\partial_{t}^2u-\Delta u=\pm(|x|^{-3}\ast|u|^2)u$ in dimensions $d\geq4$. We prove that if the radial solution $u$ with life-span $I$ obeys $(u,u_t)\in L_t^\infty(I;\dot H^{1/2}_x(\mathbb R^d)\times\dot H^{-1/2}_x(\mathbb R^d))$, then $u$ is global and scatters. By the strategy derived from concentration compactness, we show that the proof of the global well-posedness and scattering is reduced to disprove the existence of two scenarios: soliton-like solution and high to low frequency cascade. Making use of the No-waste Duhamel formula and double Duhamel trick, we deduce that these two scenarios enjoy the additional regularity by the bootstrap argument of [Dodson,Lawrie, Anal.PDE, 8(2015), 467-497]. This together with virial analysis implies the energy of such two scenarios is zero and so we get a contradiction.
Linear adjoint restriction estimates for paraboloid
Changxing Miao,Junyong Zhang,Jiqiang Zheng
Mathematics , 2015,
Abstract: We prove a class of modified paraboloid restriction estimates with a loss of angular derivatives for the full set of paraboloid restriction conjecture indices. This result generalizes the paraboloid restriction estimate in radial case by Shao, as well as the result of the authors, which is cone case. As an application, we show a local smoothing estimate for the solution of linear Schr\"odinger equation if the initial data has some angular regularity.
Maximal estimates for Schroedinger equation with inverse-square potential
Changxing Miao,Junyong Zhang,Jiqiang Zheng
Mathematics , 2014, DOI: 10.2140/pjm.2015.273.1
Abstract: In this paper, we consider the maximal estimates for the solution to an initial value problem of the linear Schroedinger equation with a singular potential. We show a result about the pointwise convergence of solutions to this special variable coefficient Schroedinger equation with initial data $u_0\in H^{s}(\R^n)$ for $s>1/2$ or radial initial data $u_0\in H^{s}(\R^n)$ for $s\geq1/4$ and the solution does not converge when $s<1/4$.
An Extremely Effective and Safe Approach of Guiding Catheter Crossing over Spasmodic Radial or (and) Brachial Artery in Patients Whose Percutaneous Coronary Intervention Was Undergone via Radial Artery Access  [PDF]
Zhuhua Ni, Lefeng Wang, Xinchun Yang, Junping Deng, Jianhong Zhao, Jiqiang Zhang, Shuying Qi, Tao Zhang, Yong Li
World Journal of Cardiovascular Diseases (WJCD) , 2018, DOI: 10.4236/wjcd.2018.82017
Abstract: Objective: Percutaneous coronary intervention (PCI) via the radial artery access has more advantages than that of femoral artery access, while radial or (and) brachial artery have tendency to be spasmodic. We sought to investigate the effectiveness and safety of guiding catheter crossing over spasmodic radial or (and) brachial artery segments by the aid of PCI wire and balloon compared with traditional anti-spasmodic approach. Methods: The clinical data of 168 patients with coronary artery disease (CAD) (group A), whose PCI was performed via radial artery access with radial or (and) brachial artery spasm or (and) dissection and guiding catheter passing through spasmodic segments successfully by the aid of PCI guiding wire and balloon were analyzed retrospectively, simultaneously, the other 73 patients (group B) who used conventional approach to cross over the spasmodic radial or (and) brachial artery segments were treated as the control. The success rate, the time consumption and the complication were compared between the two groups. Findings: There was no significant difference in the spasmodic site between the two groups (all p value > 0.05). The success rate in group A was significantly higher than that in group B (168(100%) vs 28 (38.4%), p < 0.0001). As for those of successful crossover in the two groups, the time consumption of guiding catheter crossing over spasmodic segment in group A was shorter than that in group B (p < 0.0001). The incidence of forearm hematoma in group A was lower than that in group B (7(4.2%) vs 14 (
Antioxidant Activity of Moutan Cortex Extracts by Multiple-Stage Extraction
Guoqing Xing,Zhenya Zhang,Jiqiang Liu,Peijuan Zhang
International Journal of Biology , 2010, DOI: 10.5539/ijb.v2n2p17
Abstract: Moutan cortex, a widely used traditional Chinese medicine for the treatment of various diseases, is the root bark of Peaonia suffruticosa Andrews (Paeoniaceae). In this study, the crude polysaccharides (CPS), paeonol and the crude total glycosides (CTG) of moutan cortex were extracted by the multiple-stage extraction. CPS was extracted by water, paeonol was distilled by steam distillation method, and CTG was extracted with ethanol after above two stages. The antioxidant activity of the extracts was evaluated with superoxide dismutase (SOD) and DPPH (1, 1-diphenyl-2-picryhydrazyl) radical scavenging activity assays. Among the three extracts, CTG exhibited the strongest SOD-like activity (510 U/mg) and DPPH radical-scavenging activity (EC50, 14.4 ?g/ml), CPS had a weak SOD-like activity and DPPH radical-scavenging activity. Paeonol, however, was inactive. The different biological activities among the three extracts may be attributed to differences in their chemical composition, partially supported by polysaccharides, and polyphenolic contents.
Development of National Environmental Information System

Li Ya,Zhang Jiqiang,

环境科学 , 1991,
Abstract: National Environmental Information System" (NE-1S) was a National Key Project of the 7th 5-year Plan. The research background, methodology of the project at well as the structure, scale, main functions of NEIS and its further development objectives in the 8th 5-year Plan Period were discribed in this paper. The current situation of the information techniques was also outlined.
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