Mobility of metal(loid)s in Pb/Zn tailings under different revegetation strategies.

Metal tailings are potential sources of strong environmental pollution. In situ remediation involves the installation of a plant cover to stabilize materials and pollutants. Whether metal(loid)s are effectively immobilized in remediated tailing ponds submitted to heavy rainfall remains uncertain. In this study, tailing materials were collected from bare tailings (control), grass-planted (G) and grass-shrub planted (GS) areas on a former Pb/Zn mine site. Batch column experiments were performed with three rainfall intensities of 0.36, 0.48, and 0.50 mL min-1 for 18 d in the lab. The pH, Eh, Cd, Pb, Zn and As concentration in leachate were recorded. Selected leached tailing materials were finally characterized. Results showed that leachates from control were strongly acidic (pH 3.11-4.65), and that Cd, Pb, Zn and As were quickly released at high rate (e.g., 945 mg L-1 Zn). During the experiment up to 4% Cd present in the material was released and almost 1% Zn. With material collected from the G area, leachates were even more acidic (2.16-2.84) with a rainfall intensity of 0.50 mL min-1 and exhibited a high redox potential (588-639 mV). However, concentrations of metals in leachates were much lower than that in the control, except for Zn (e.g., 433 mg L-1), and they tended to decrease with time. Cumulative leaching rate was still relatively high (e.g., 0.68% Cd; 0.75% Zn) during the first eight days (stage I). However, with the GS treatment, leachate pH gradually raised from acid to alkaline values (3.9-8.2) during stage I, then remained high until the end of the experiment (stage II). Also, amounts of elements released during the 18 d were low in general. The releasing ratios of Cd (R2 > 0.95), Pb (R2 > 0.95), As (R2 > 0.87), and Zn (R2 > 0.90) fitted well with a two-constant model. In conclusion, under subtropical climate with heavy rainfall, phytostabilization is effective but immobilization of metals is higher with a combination of grass and shrub than with only grass to reduce leaching of As and Zn.

Theoretical Insights into the Interaction Mechanisms between Nitric Acid and Nitrous Oxide Initiated by an Excess Electron.

Nitric acid (HNO3) and nitrous oxide (N2O) play an important role in the atmospheric chemistry in regulating the global environment and climate changes. In this study, the interaction mechanisms between them have been systematically investigated before and after the electron capture employing the density functional theory in combination with the AIM, NBO, and ab initio molecular dynamics calculations. It was found that HNO3 and N2O can form transient complexes through intermolecular H-bonds. HNNO, OH, and NO2 free radicals can be produced after the electron capture of the formed complexes, providing an alternative source of these radicals in the atmosphere. The present results not only can provide new insights into the transformation of the HNO3 and N2O atmospheric species but also can enable us to better understand the potential role of the free electron in the atmosphere.

Theoretical Investigations on the Reactivity of Hydrogen Peroxide toward 2,3,7,8-Tetrachlorodibenzo-p-dioxin.

Acquiring full knowledge of the reactivity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is crucial for the better understanding of the transformation and degradation of TCDD-like dioxins in the environment. To clarify the reactivity of the organic hydroperoxides toward TCDD, in this study, the reactions between the neutral/anion of the hydrogen peroxide (H2O2) and TCDD have been systematically investigated theoretically. It was found that the neutral H2O2 is relatively difficult to react with TCDD compared with its anion, exhibiting the pH dependence of the title reaction. As for the anion of H2O2, it reacts with TCDD through two reaction mechanisms, i.e., nucleophilic substitution and nucleophilic addition. For the former, the terminal O atom of HO2- nucleophilically attacks the C atom of the C-Cl bond in TCDD to form an intermediate containing an O-O bond, accompanying the dissociation of the chlorine atom. For the latter, the terminal O atom of HO2- can be easily attached to the C atom of the C-O bond in TCDD, resulting in the decomposition of C-O bond and the formation of an intermediate containing an O-O bond. For these formed intermediates in both reaction mechanisms, their O-O bonds can be homolytically cleaved to produce different radicals. In addition, the selected substitution effects including F-, Br-, and CH3- substituents on the above reactions have also been studied. Hopefully, the present results can provide new insights into the reactivity of the organic hydroperoxides toward TCDD-like environmental pollutants.

Theoretical Insights into the Electron Capture Behavior of H2SO4···N2O Complex: A DFT and Molecular Dynamics Study.

Both sulfuric acid (H2SO4) and nitrous oxide (N2O) play a central role in the atmospheric chemistry in regulating the global environment and climate changes. In this study, the interaction behavior between H2SO4 and N2O before and after electron capture has been explored using the density functional theory (DFT) method as well as molecular dynamics simulation. The intermolecular interactions have been characterized by atoms in molecules (AIM), natural bond orbital (NBO), and reduced density gradient (RDG) analyses, respectively. It was found that H2SO4 and N2O can form two transient molecular complexes via intermolecular H-bonds within a certain timescale. However, two molecular complexes can be transformed into OH radical, N2, and HSO4- species upon electron capture, providing an alternative formation source of OH radical in the atmosphere. Expectedly, the present findings not only can provide new insights into the transformation behavior of H2SO4 and N2O, but also can enable us to better understand the potential role of the free electron in driving the proceeding of the relevant reactions in the atmosphere.

Theoretical Investigations on the Reactivity of Methylidyne Radical toward 2,3,7,8-Tetrachlorodibenzo-p-Dioxin: A DFT and Molecular Dynamics Study.

To explore the potential reactivity of the methylidyne radical (CH) toward 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the reaction mechanism between them has been systematically investigated employing the density functional theory (DFT) and ab initio molecular dynamics simulations. The relevant thermodynamic and kinetic parameters in the possible reaction pathways have been discussed as well as the IR spectra and hyperfine coupling constants (hfcc's) of the major products. Different from the reaction of the CH radical with 2,3,7,8-tetrachlorodibenzofuran, CH radical can attack all the C-C bonds of TCDD to form an initial intermediate barrierlessly via the cycloaddition mechanism. After then, the introduced C-H bond can be further inserted into the C-C bond of TCDD, resulting in the formation of a seven-membered ring structure. The whole reactions are favorable thermodynamically and kinetically. Moreover, the major products have been verified by ab initio molecular dynamics simulations. The distinct IR spectra and hyperfine coupling constants of the major products can provide some help for their experimental detection and identification. In addition, the reactivity of the CH radical toward the F- and Br-substituted TCDDs has also been investigated. Hopefully, the present findings can provide new insights into the reactivity of the CH radical in the transformation of TCDD-like dioxins.

Ab Initio Molecular Dynamics Simulation Study on the Stereo Reactions between Atomic Oxygen Anion and Methane.

Ion⁻molecule reaction between atomic oxygen anion (O-) and methane (CH4) has been systematically investigated employing the on-the-fly ab initio molecular dynamics simulations. Besides the major H-abstraction process as the exothermic reaction studied widely, an endothermic pathway to produce OCH3- and H is also observed in this study. Three typical O- attack modes with reference to the pyramid structure of CH4 fixed in space have been considered. It was found that the internal motions of the radical products are significantly dependent on the O- attack modes. As for the reaction between O- and the thermally vibrating CH4, the major pathway to produce OH- and CH3 is preferred by the direct H-abstraction and the minor pathway to produce H and OCH3- is the roaming reaction via the transient negative ion [HO-CH3]-.

Insights into the Reaction Mechanism of Criegee Intermediate CH2OO with Methane and Implications for the Formation of Methanol.

Criegee intermediates (CIs) play a key role in controlling the atmospheric budget of hydroxyl radical, organic acids, and secondary organic aerosols. In this study, the detailed reaction mechanisms of the simplest Criegee intermediate CH2OO and its derivatives with methane (CH4) have been systematically investigated theoretically. Two pathways A and B have been identified for the title reaction. In pathway A, CIs can act as an oxygen donor by inserting its terminal oxygen atom into the C-H bond of alkanes, resulting in the formation of alcohol species. The corresponding energy barriers ranging from 6.5 to 24.1 kcal/mol are associated with the O-O bond strength of CIs. Meanwhile, this pathway is more favorable thermodynamically, where the free energy changes (enthalpy changes) range from -81.1 (-78.3) to -110.9 (-109.0) kcal/mol, respectively. In pathway B, an addition reaction to produce the hydroperoxides occurs, accompanying the hydrogen transfer from the alkanes to the terminal oxygen atom of CIs. The corresponding energy barriers ranging from 17.3 to 30.9 kcal/mol are higher than those in pathway A. Further calculations of the rate constants suggest that pathway A is the most favorable reaction channel and the rate constant exhibits a positive temperature dependence. In addition, the conformation-dependent reactivity for the title reaction has been observed. The present findings can enable us to better understand the potential reactivity of CIs in the presence of the alkane species.

Ab initio molecular dynamics simulation study of dissociative electron attachment to dialanine conformers.

Dissociative electron attachment (DEA) processes of six low-lying conformers (1-6) of dialanine in the gas phase are investigated by using ab initio molecular dynamics simulations. The incoming electron is captured and primarily occupies the virtual molecular orbital π*, which is followed by the different dissociation processes. The electron attachments to conformers 1 and 2 having the stronger N-H···N and O-H···O intramolecular hydrogen bonds do not lead to fragmentations, but two different backbone bonds are broken in the DEAs to conformers 3 (or 4) and 6, respectively. It is interesting that the hydrogen abstraction of -NH from the terminal methyl group -CH3 is found in the roaming dissociation of the temporary anion of conformer 3. The present simulations enable us to have more insights into the peptide backbone bond breaks in the DEA process and demonstrate a promising way toward understanding of the radiation damages of complicated biological system.

Dissociative electron attachments to ethanol and acetaldehyde: A combined experimental and simulation study.

Dissociation dynamics of the temporary negative ions of ethanol and acetaldehyde formed by the low-energy electron attachments is investigated by using the anion velocity map imaging technique and ab initio molecular dynamics simulations. The momentum images of the dominant fragments O(-)/OH(-) and CH3 (-) are recorded, indicating the low kinetic energies of O(-)/OH(-) for ethanol while the low and high kinetic energy distributions of O(-) ions for acetaldehyde. The CH3 (-) image for acetaldehyde also shows the low kinetic energy. With help of the dynamics simulations, the fragmentation processes are qualitatively clarified. A new cascade dissociation pathway to produce the slow O(-) ion via the dehydrogenated intermediate, CH3CHO(-) (acetaldehyde anion), is proposed for the dissociative electron attachment to ethanol. After the electron attachment to acetaldehyde molecule, the slow CH3 (-) is produced quickly in the two-body dissociation with the internal energy redistributions in different aspects before bond cleavages.

The GLCCI1 rs37973 variant and the efficacy of inhaled corticosteroids in the treatment of asthma: A meta-analysis.

OBJECTIVE: This study investigated the relationship between the glucocorticoid-induced transcript 1 (GLCCI1) gene variant and the degree of improvement in lung function with inhaled corticosteroids (ICS). METHODS: We searched the PubMed, Embase, Cochrane Library, CBM, CNKI and Wanfang databases to obtain studies on the GLCCI1 rs37973 variant and the efficacy of ICS in asthma. RESULTS: The overall meta-analysis showed that patients with the GG phenotype (mutant homozygotes) exhibited significantly smaller forced expiratory volume in 1 sec (FEV1) change than patients with the AG phenotype (mutant heterozygous) (MD = -0.08, 95% CI [-0.12, -0.03], P = 0.001). Compared with the AA phenotype (wild homozygotes), the GG phenotype (MD = -4.23, 95% CI [-6.09, -2.38], P < 0.00001) and AG phenotype (MD = -1.92, 95% CI [-2.35, -1.49], P < 0.00001) had significantly smaller FEV1%pred changes. The FEV1 change subgroup analysis showed that the GG phenotype group was smaller than the AA phenotype group at 8 (MD = -0.53, 95% CI [-0.91, -0.14], P = 0.007), 12 (MD = -0.16, 95% CI [-0.30, -0.02], P = 0.02) and 24 (MD = -0.09, 95% CI [-0.17, -0.01], P = 0.02) weeks of treatment; the GG phenotype group was smaller than the AG phenotype group at 12 weeks (MD = -0.08, 95% CI [-0.15, -0.01], P = 0.02). CONCLUSION: This meta-analysis suggests that the GLCCI1 rs37973 variant affects the efficacy of ICS and that the presence of the G allele attenuates the improvement in lung function with ICS.

Solution-phase controlled synthesis of Cu3NbSe4 nanocrystals for optoelectronic applications.

Cu3MX4 (M = V, Nb, and Ta; X = S, Se, and Te) compounds have recently emerged as greatly promising solar energy conversion materials due to their tailorable band gaps, high optical absorption coefficients, environmentally benign nature and comparatively abundant elements. However, solution synthesis of Cu3NbSe4 nanocrystals as a photoactive material for investigating their optoelectronic properties has not yet been reported. Herein, we present a facile synthesis of cube-shaped Cu3NbSe4 nanocrystals with high crystallinity, high uniformity and monodispersity. Studies of the formation process disclose that the reaction temperature, time and surface ligand play significant roles in determining the crystalline phase, size and morphology evolution of the Cu3NbSe4 nanocrystals. Excitingly, a Cu3NbSe4-based photodetector exhibits a high Ilight/Idark ratio of 35, fast response speeds of 0.3/0.1 s for rise/fall times and excellent stability, indicating its robust potential for application in electronics and optoelectronics.

Novel solution synthesis of the overlooked cubic phase Cu2GeTe3 nanocrystals for optoelectronic devices.

Herein, for the first time, we present a novel solution method for controllable synthesis of the overlooked cubic phase Cu2GeTe3 nanocrystals. The resulting Cu2GeTe3 nanocrystals are of high quality with monodispersed size and uniform shape. Optical characterization demonstrates that Cu2GeTe3 nanocrystals have a broad absorption in the visible to near-infrared region. Furthermore, an optoelectronic device based on Cu2GeTe3 nanocrystals exhibits excellent stability, reproducibility and responsivity. The novel synthetic route presented here not only can open a new avenue for fabricating Cu2GeTe3 nanocrystals, especially at the nanoscale, but also may further expand their applications.

Controllable synthesis of non-layered two-dimensional plate-like CuGaSe2 materials for optoelectronic devices.

CuGaSe2 semiconductor materials, as an important member of the I-III-VI2 family, have sparked tremendous attention due to their fascinating structure-related properties and promising applications in solar energy storage and conversion. Nevertheless, the controllable preparation of two-dimensional (2D) CuGaSe2 structures is still a daunting challenge owing to the intrinsic non-layered crystal structure and inaccessible reactivity-matching of multiple reaction precursors, which will seriously impede the much deeper research progress on their properties and applications. Herein, non-layered 2D CuGaSe2 plates possessing high crystallinity, and uniform size and morphology have been first synthesized by a feasible cation exchange strategy. Because the fabrication of 2D CuGaSe2 crystals is rarely reported, a particular highlight is laid on the compositional analysis, structural characterization, and formation mechanism. Furthermore, the optical absorption and optoelectronic measurements reveal that the as-synthesized CuGaSe2 plates exhibit high light harvesting capacity and excellent photoelectric performance. This study opens up a new avenue for the feasible fabrication of non-layered CuGaSe2 plates possessing a high-quality crystalline structure and provides a promising candidate for the development of novel solar energy conversion and storage devices.

Theoretical Insights into the Reaction Mechanism between 2,3,7,8-Tetrachlorodibenzofuran and Hydrogen Peroxide: A DFT Study.

A detailed knowledge of the reactivity of 2,3,7,8-tetrachlorodibenzofuran (TCDF) at the molecular level is important to better understand the transformation of dioxins analogous to TCDF in the environment. To clarify the reactivity of the organic hydroperoxides toward TCDF, the reaction of the TCDF with hydrogen peroxide (H2O2) and its anion has been investigated theoretically. For the reaction of the neutral H2O2, a molecular complex can be formed between TCDF and H2O2 first. Then, the nucleophilic aromatic substitution of TCDF by H2O2 occurs in the presence of the water molecules to form an intermediate containing an O-O bond. Finally, the O-O bond cleavages homolytically for the above intermediate. On the other hand, as for the reaction of the anion of H2O2 (HO2 -), the nucleophilic addition of HO2 - to TCDF can also occur besides the nucleophilic aromatic substitution reaction mentioned above, resulting in the dissociation of the C-O bond of TCDF. Unlike the reaction involving neutral H2O2, no water molecules are required. In addition, the selected substitution effects, such as F-, Br-, and CH3-substituents, on the reactivity of the above reaction have also been explored. Hopefully, the present results can enable us to gain insights into the reactivity of the organic hydroperoxides with TCDF-like environmental pollutants.

Sliding bone graft combined with double locking plate fixation for the treatment of femoral shaft nonunion.

OBJECTIVES: The aim of this study was to describe and evaluate a novel method of sliding bone graft combined with double locking plate fixation in treating femoral shaft nonunion. METHODS: Clinical data from patients with femoral shaft nonunion that was treated with sliding bone grafts combined with double locking plate fixation were retrospectively collected. Data included duration of surgery, blood loss, union rate, time to union and possible complications. RESULTS: Twenty-five patients included in the study were followed for a mean duration of 16.6 ± 2.6 months (range, 12-22 months). All of the fractures (100%) achieved bony union. Mean time to union was 6.0 ± 1.0 months (range, 4-8 months). No infections or medullary cavity occlusions were observed. CONCLUSIONS: Sliding bone graft combined with double locking plate fixation was shown to be a safe, effective, and convenient surgical option for the treatment of nonunion, due to its high union rates with no complications. Further studies with larger sample sizes and longer-term follow-up are warranted.

Theoretical insights into the reaction mechanisms between 2,3,7,8-tetrachlorodibenzofuran and the methylidyne radical.

To explore the potential role of the methylidyne radical (CH) in the transformation of 2,3,7,8-tetrachlorodibenzofuran (TCDF), in this study, the detailed reaction mechanisms between TCDF and CH radical have been systematically investigated employing the B3LYP method of density functional theory (DFT) in combination with the atoms in molecules (AIM) theory and ab initio molecular dynamics. It was found that the title reaction is a multi-channel reaction, i.e., the CH radical can attack the C-X (X = C, Cl, H, O) bonds of TCDF via the insertion modes, resulting in the formation of 13 products. Thermodynamically, the whole reaction processes are exothermic and spontaneous since all the enthalpy and Gibbs free energy changes are negative values in the formation processes. Moreover, the thermodynamic stability of the products is controlled by the distribution of the single unpaired electron. Kinetically, the most favorable reaction channel is the insertion of the CH radical into the C-C bond except for the C atoms attached to the chlorine atom. Moreover, the dominant products have been further confirmed by the molecular dynamics. Meanwhile, the IR spectra and hyperfine coupling constants of the dominant products have been investigated to provide helpful information for their identification experimentally. In addition, the reactivity of the CH radical toward the F- and Br-substituted TCDFs has also been investigated. Expectedly, the present findings can enable us to better understand the reactivity of the CH radical toward organic pollutants analogous to TCDF in the atmosphere.

Three-dimensional finite element analysis and comparison of a new intramedullary fixation with interlocking intramedullary nail.

This study was set to introduce a new intramedullary fixation, explore its biomechanical properties, and provide guidance for further biomechanical experiments. With the help of CT scans and finite element modeling software, finite element model was established for a new intramedullary fixation and intramedullary nailing of femoral shaft fractures in a volunteer adult. By finite element analysis software ANSYS 10.0, we conducted 235-2,100 N axial load, 200-1,000 N bending loads and 2-15 Nm torsional loading, respectively, and analyzed maximum stress distribution, size, and displacement of the fracture fragments of the femur and intramedullary nail. During the loading process, the maximum stress of our new intramedullary fixation were within the normal range, and the displacement of the fracture fragments was less than 1 mm. Our new intramedullary fixation exhibited mechanical reliability and unique advantages of anti-rotation, which provides effective supports during fracture recovery.

Theoretical study on ion-pair recognition of M(+)X(-) (M = Li, Na, K and X = F, Cl, Br) by formylaminocalix[4]arene derivatives.

DFT calculations were reported for calix[4]arene derivatives [i.e., formylaminocalix[4]arene (1) and formylaminocalix[4]bis-crown-3 (2)] binding cations M(+) (Li(+), Na(+), and K(+)) and anions X(-) (F(-), Cl(-), and Br(-)) simultaneously. The B3LYP function together with the LANL2DZp basis set was used in order to obtain insights into the factors determining the nature of the interactions of these compounds with X(-) and M(+). Based on the molecular electrostatic potential (MEP) analysis, the result complexes M(+)X(-)/H (H = 1, 2) were investigated. For all the complex structures, the most pronounced changes in geometric parameters upon interaction were observed in the host segment compared with the free receptors. Two main types of driving force, N-H∙∙∙X(-) hydrogen bonds and electrostatic interactions between M(+) and oxygen atoms, were confirmed. The recognition trends for 1 and 2 toward M(+)X(-) followed the same order: M(+)F(-) > M(+)Cl(-) > M(+)Br(-) (M(+) is same to each other) and Li(+)X(-) > Na(+)X(-) > K(+)X(-) (X(-) is same to each other). The binding energy, enthalpy change, Gibbs free energy change, and entropy change of complexation formation have been studied by the calculated thermodynamic data. In all cases, the inclusion energy changes with 2 were more negative than those with 1, correlating with the flexible space available by the two crown ether moieties in 2. The calculated results of the model system have been reported and should be useful to the experimental research in this field.

[Treatment of traumatic bone defect with graft material of allogenic cancellous combined with autologous red marrow].

OBJECTIVE: To study clinical effects of the graft material of allogenic cancellous combined with autologous red marrow in the treatment of traumatic bone defect. METHODS: From February 2002 to April 2006, 38 patients of traumatic bone defect, 25 males and 13 females, aged 21-68 years old (38 on average), were treated with allogenic cancellous combined with autologous red marrow. Among them, there were 11 cases of bone nonunion caused by failure of internal fixation, 13 of serious comminuted fracture, 9 of bone defect caused by open fractures or bone infection, 5 of old fracture in need of graft. Of these fractures, there were 8 cases of shaft of humerus, 4 of intercondylar comminuted fracture of humerus, 8 of intercondylar comminuted fracture of femur, 5 of shaft of femur, 4 of open tibia fracture (Gustilo I, II type) and 9 of tibial plateau fracture. They included 17 cases of fresh fracture and 21 of old fracture. There were 23 cases of limitations of bone defect, and the range was 3 cm x 3 cm x 2 cm - 7 cm x 4 cm x 3 cm; and the range of the large bone defect was less than 3 cm in 15 cases. According to AO/ASIF classification, there were 5 cases of type B2, 10 of type B3, 16 of type C2 and 7 of type C3. The time from fresh fracture to operation was 5-17 days (8 days on average), and the time from old fracture to operation was 5-13 months (7.5 months on average). The amount of the allograft implantation was 20-50 g (28 g on average). RESULTS: The wounds in all 38 cases obtained healing by first intention. All the patients were followed up for 8 months to 4 years (3.2 years on average). The X-ray films at reexamination showed that 36 patients had bone healing, with fresh fracture healing time of 2-6 months (4 months on average) and old fracture healing time of 3-10 months (7 months on average). The allogenic cancellous particles began to be fused with autogenous bone through creeping substitution 6-8 weeks after operation. One case, which had delayed infection, had bone union by removing internal fixation, placing irrigating tube and grafting after local stability. During the follow-up of 25 months, no relapse was found. Another case had nonunion because of plate loosening. According to the Mankin and Komender standard evaluation, there were 36 cases with satisfaction (94.7%) and 2 with dissatisfaction (5.3%). CONCLUSION: The composite graft material of allogenic cancellous combined with autologous red marrow is safe and effective for repairing fractures and bone defect.

[Experimental study of repairing bone defect by staphylococcus aureus injection carried in collagen membrane].

OBJECTIVE: To validate the advantage of repairing bone defect by staphylococcus aureus injection carried in collagen membrane. METHODS: Twenty-four adult New Zealand rabbits were divided into two groups randomly. After the experimental model of standard bone defect had been made by operation, collagen membrane/staphylococcus aureus injection and staphylococcus aureus injection with the same quantity were transplanted in bone defect areas of the two groups respectively. The reconstructed tissues were observed by general method, X-ray, histology, and immunohistochemistry at 2nd, 4th, 6th, 8th week respectively. RESULTS: The experimental group showed that new bone proliferated distinctly in bone defect area and the proliferation lasted long, and no excessive connective tissue in defect area. X-ray observation showed that there was continual callus growth in transplantation area in early stage and the distribution of new bones was even in the group. Histological observation showed that there were many new bone growth centers in bone defect area, trabecular bones were sequentially distributed, and mature bone replacement was complete. Immunohistochemical examination showed that bone morphogenetic protein (BMP) could be seen for a long time and BMP took up a large part in the new bone tissues. CONCLUSION: Collagen membrane could prevent parenchyma from penetrating into bone defect area and provide room for new bone growth. As the carrier of staphylococcus, collagen membrane could reduce the overflow of staphylococcus and improve its curative effect as well.