磷酸盐修复重金属污染土壤的研究进展

从研究方法、反应机理以及风险评价等方面综述了磷酸盐修复重金属污染土壤的研究进展,分析和讨论了其中存在的问题和不足,提出了今后加强研究的重点。目前磷酸盐修复重金属污染土壤时,使用的主要研究方法有化学形态提取法、化学平衡形态模型法和光谱及显微镜技术,各个方法都有其优缺点,应该结合使用并探索新方法。磷酸盐稳定重金属的作用机理主要有3个:磷酸盐诱导重金属吸附、磷酸盐和重金属生成沉淀或矿物和磷酸盐表面吸附重金属,但磷酸盐与重金属反应的机理十分复杂,人们尚不完全清楚,因此难以有效区分和评价诱导吸附机理和沉淀机理或其它固定机理,相应地对磷酸盐修复重金属的长期稳定性难以预测。磷酸盐修复重金属污染土壤时由于其较高的施用量可能会造成磷的积聚从而引发一些环境风险,如磷淋失造成水体富营养化,营养失衡造成作物必需的中量和微量元素缺乏以及土壤酸化等。所以应该谨慎选择磷肥种类和用量,最好是水溶性磷肥和难溶性磷肥配合、磷肥与石灰物质等配合施用。今后应着重研究磷酸盐与重金属相互作用的机理区分和评价;关注磷酸盐修复重金属污染土壤时存在的潜在风险,特别是加强植物长期不断吸收磷或其它环境条件变化致使土壤磷素持续减少过程中稳定的重金属溶解性和移动性的研究,磷酸盐修复重金属污染土壤的长期田间实践等。

A New Approach for Impulsive Stabilization of Liu's System

An impulsive control scheme of Liu＇s system is presented in this paper. Some less conservative conditions with impulses at fixed times are provided, which can guarantee the global asymptotical stability and global exponential stability for the impulsive control of Liu＇s systems. We also present the estimate of the stable region for the equidistance impulsive interval. Furthermore, an illustrative example is given to show the effectiveness of the proposed results.

Molecular Dynamics Simulation on Stability of Insulin on Graphene

The adsorption dynamics of a model protein （the human insulin） onto graphene surfaces with different sizes was investigated by molecular dynamics simulations. During the adsorption, it has different effect on the stability of the model protein in the fixed and non-fixed graphene systems. The tertiary structure of the protein was destroyed or partially destroyed, and graphene surfaces shows the selective protection for some α-helices in non-fixed Systems but not in fixed systems by reason of the flexibility of graphene. As indicated by the interaction energy curve and trajectory animation, the conformation and orientation selection of the protein were induced by the properties and the texture of graphene surfaces. The knowledge of protein adsorption on graphene surfaces would be helpful to better understand stability of protein on graphene surfaces and facilitate potential applications of graphene in biotechnology.

Global exponential stability of interval neural networks with a fixed delay

The problem of the global exponential robust stability of interval neural networks with a fixed delay was studied by an approach combining the Lyapunov-Krasovskii functional with the linear matrix inequality (LMI). The results obtained provide an easily verified guideline for determining the exponential robust stability of delayed neural networks. The theoretical analysis and numerical simulations show that the results are less conservative and less restrictive than those reported recently in the literature.

PERCUTANEOUS REDUCTION AND STABILIZATION OF COMPLEX TIBIAL PLATEAU FRACTURES

Mechanical traction and percutaneous reduction by leverage and fixation by a bilateral groove externalfixator were performed on 23 patients with complex tibial plateau fractures involving a depressed and splitfragments. The fixator is composed of two long groove frames, three to five nuts, hooked bolts and Stein-manns pins.All fractures united in good position in three months with no incision (only pinpricks), llttle operativetrauma and no significant complications but pintract infection, and the flexion-extension range of kneemovement was excllent in all patients, so that this technique is particularly advisable for complex tibialplateau fractures.

Highly selective and stable hydrogenation of heavy aromatic-naphthalene over transition metal phosphides

The present study reports a highly selective and stable catalytic approach for producing tetralin, an important chemical, solvent, and H2 storage material. Transition metal phosphides （MOP, Ni2P, Co2P, and Fe2P） were prepared by wet impregnation and temperature-programmed reduction and characterized by X-ray diffraction （XRD）, energy dispersive X-ray spectroscopy （EDX）, EDX mapping, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, brunauer-emmett- teller （BET）, temperature-programmed desorption of ammonia （NH3-TPD）, and fourier transform infrared spectroscopy of pyridine （pyridine-FTIR）. Of all the transition metal phosphides MoP was formed at a lower reduction temperature, which resuited in smaller particle size that enhanced the overall surface area of the catalyst. The existence of weak, moderate, and Lewis acidic sites over MoP were responsible for its high tetralin selectivity （90%） and stability during the 100 h reaction on-stream in a fixed-bed reactor.

Posterior fixation and fusion with atlas pedicle screw system for upper cervical diseases

Objective： To evaluate the feasibility, safety and efficacy of atlas pedicle screws system fixation and fusion for the treatment of upper cervical diseases. Methods： Twenty-three consecutive patients with upper cervical disorders requiring stabilization, including 19 cases of atlantoaxial dislocation （4 congenital odontoid disconnections, 6 old odontoid fractures, 4 fresh odontoid fractures of Aderson Ⅱ C, 3 ruptures of the C1 transverse ligament, and 2 fractures of C1）, 2 cases of C2 tumor （instability after the resection of the tumors）, and 2 giant neurilemomas of C2-C3（instability after resection of the tumors）, were treated by posterior fixation and fusion with the atlas pedicle screw system, in which the screws were inserted through the posterior arch of C1. The operative time, bleeding volume and complications were reported. All patients were immobilized without external fixation or with rigid cervical collars for 1-3 months. All patients were followed up and evaluated with radiographs and CT. Results： In the 23 patients, 46 C1 pedicle screws, 42 C2 pedicle screws and 6 lower cervical lateral mass screws and 2 lower cervical pedicle screws were placed. The mean operative time and bleeding volume was 2.7 hours and 490 ml respectively. No intraoperative complications were directly related to surgical technique. No neurological, vascular or infective complications were encountered. All patients were followed up for 3-36 months （average 15 months）. Firm bony fusion was documented in all patients after 3-6 months. One patient with atlas fracture showed anterior occipitocervical fusion. There was no implant failure. Conclusions： Posterior fixation and fusion of the atlas pedicle screw system is feasible and safe for the treatment of upper cervical diseases, and may be applicable to a larger number of patients.

Ipsilateral fracture dislocations of the hip and knee joints with contralateral open fracture of the leg： a rare case and its management principles

This paper discussed the injury mechanism and management of a patient who had concomitant ipsilateral hip and knee dislocations and contralateral open leg fracture. A 32-year-old man presented with ipsilateral fracturedislocations of the left hip （Pipkin＇s type IV） and knee （Moore II）joints and contralateral open fracture of the leg bones after a car accident. After emergency resuscitative measures, the hip joint was reduced and Pipkin＇s fracture was fixed using Ganz approach with lag screws; knee joint was reduced closely and tibial plateau fracture was stabilized with lateral buttress plate and a transarticular spanning fixator. The open fracture on the other leg was debrided and fixed with an external fixator. There was no insta-bility in both joints after fixation when he was examined under anesthesia. The fractures united after 3 months and the patient had no residual instability of hip and knee. There was no clinical or radiological evidence of osteonecrosis in the hip joint after 6 months. At one-year follow-up, he had satisfactory functional outcome with almost normal range of motion at both joints. Ipsilateral hip and knee dislocations are rare injuries and more caution is needed for early diagnosis. A timely appropriate intervention can provide good functional outcome to the patient in this situation.

Macroscopic model for biological fixation and its uncovering idea in Chinese Mongolian traditional osteopathy

Splintage external fixation in Chinese Mongolian osteopathy is a biological macroscopic model. In this model, the ideas of self-life ＂unity of mind and body＂ and vital natural ＂correspondence of nature and human＂ combine the physiological and psychological self-fixation with supplementary external fixation of fracture using small splints. This model implies macroscopic ideas of uncovering fixation and healing： structural stability integrating geometrical ＂dynamic＂ stability with mechanical ＂dynamic＂ equilibrium and the stability of state integrating statics with dynamics, and osteoblasts with osteoclasts, and psychological stability integrating closed and open systems of human and nature. These ideas indicate a trend of development in modern osteopathy.

The preparation of supported ionic liquids (SILs) and their application in rare metals separation

This review summarizes the preparation methods of support ionic liquids （SILs） and their applications in rare metals separation The rare metals separation includes the recovery of high value metal ions and the removal of heavy metal ions from wastewater. SILs can be used as a kind of highly efficient multifunctional separation materials. The preparation methods of SILs include chemical immobilization technique in which ILs moieties are supported on solid supports via covalent bonds and physical immobilization techniques in which ILs are immobilized on solid supports via physical method such as simple im- pregnation, sol-gel method. According to the difference of solid supports, this review summarizes the application of polymer supported ionic liquids （P-SILs）, silica based material supported ionic liquids （SM-SILs） and membrane supported ionic liq- uids （M-SILs） in rare metals separation, P-SILs and SM-SILs prepared by chemical method with N-methylimidazolium group can be used as highly efficient anion exchangers with high thermal stability and good chemical stability for adsorption of Cr（Ⅵ）, Re（Ⅶ）, Ce（Ⅳ）. P-SILs prepared via simple impregnation afforded IL functionalized solvent impregnated resins （SIRs） which showed high separation efficiency and selectivity in the separation of rare earths（Ⅲ） （REs（Ⅲ））. SM-SILs prepared via sol-gel method with IL doped in the support as porogens or extractant show high removal efficiencies and excellent stability for the separation of RE（Ⅲ）, Cr（Ⅲ） and Cr（Ⅵ）. M-SILs with IL as plasticizer or carrier show improved stability, high perme- ability coefficient and good selectivity for Cr（VI） transport. Different supports and different supporting methods were suffi- ciently compared. Based on the different practical application, different forms of SILs can be prepared for separation of rare metals with high separation efficiency and selectivity.

Stability range of tilted dendritic arrays during directional solidification

The stability range of primary spacing of the tilted dendritic arrays in directional solidification has been studied by quantitative phase-field simulations. Results show that both the real growth direction and morphological shapes of dendritic arrays change with the primary spacing for different misorientation angles(θ0). It has been found that the lower limit of primary spacing is independent of θ0, but the upper limit of primary spacing is strongly influenced by that. The two kinds of tertiary branching instabilities result in different behaviors of the variation of the upper limit with misorientation angle for different pulling velocities.

Fixed points of Scott continuous self-maps

In this paper we study the properties of the set consisting of all fixed points of a Scott continuous self-map between domains. All the results give an answer to an open problem posed by Lawson and Mislove in 1990.

Biomechanical Effect of Chinese Immobilization Using Little Splint

Immobilization using little splint is an original innovation of Chinese people for the fracture fixation, which is simple to use and clinically effective. It was found that Chinese immobilization using little splint can make the non-invasive,uncovering, and trouble free healing of bone fracture via harmonious unity of the structure stability and the force balance, of the motion stability and the stress adaptability, of the constant and discontinuous physiological stress. The biomechanical effect of Chinese immobilization using little splint, including entirety, dynamic, and functional fixity, is the root cause of its inheritance and the use up to now, and also is a direction of today's fracture fixation towards personalization, individuality and entirety.

A NEW SIMPLE 2-D PIECEWISE LINEAR MAP

A new simple piecewise linear map of the plane is presented and analyzed, then a detailed study of its dynamical behaviour is described, along with some other dynamical phenomena, especially fixed points and their stability, observation of a new chaotic attractors obtained via border collision bifurcation. An important resuk about coexisting chaotic attractors is also numerically studied and discussed.

Modified lumbopelvic fixation for sacral and L5 fractures associated with spinopelvic instability： a case report and introduction of the surgical technique

Posterior lumbopelvic fixation with iliac screws is the most commonly used method for unstable spinopelvic injuries. It has certain limitations including inability to use distraction along the spinopelvic rod as an indirect reduction maneuver, need for complex 3-dimensional rod contouring and complications such as hardware prominence and soft tissue coverage. In the present case report,we described a surgical technique of lumbopelvic fixation with sacral alar screws for traumatic spinopelvic instability resulted from a unilateral Denis-Ⅲ comminuted sacral fracture and the L5 burst fracture. On the opposite side of the sacral fracture, caudal screws were implanted into the pedicle of the S1, whereas on the side of sacral fracture, two sacral alar screws were placed parallel to the superior sacral endplate as well as the plane of sacroiliac joint. In addition,horizontal stabilization was conducted with cross-link connections to maintain the longitudinal traction. For sacral fracture associated with traumatic spinopelvic instability,this modified lumbopelvic fixation technique using sacral alar screws makes longitudinal reduction easier, requires less rod contouring, and reduces hardware prominence without compromising the stability.

EFFECT OF CROSS DIFFUSION IN A COMPETITION MODEL WITH STAGE STRUCTURE

The purpose of this paper is to study the effect of cross diffusion in a competition model with stage structure, under homogeneous Neumann boundary condition. It will be shown that cross diffusion cannot only destabilize a uniform positive equilibrium, it can also help diffusion to induce instability of the uniform positive equilibrium. Moreover, stationary patterns can arise from the effect of cross diffusion.