Numerical Investigation of Tree-Type Hydraulic Fracturing for Balanced Permeability Enhancement of Heterogenous Coal Seams Based on the Finite-Discrete Element Method Model.

Tree-type hydraulic fracturing (TTHF) is a new technology that can enhance the permeability of coal seams in a balanced manner and increase the coalbed methane production rate. However, the heterogeneity of coal seams is a major challenge in achieving balanced permeability enhancement by TTHF. Traditional methods based on digital image processing are difficult to apply in practice. To address these challenges, we proposed a 2D numerical model of coal seams based on the combined finite-discrete element method (FDEM). The elastic modulus of the coal seams obeys a Weibull distribution, and the coal heterogeneity was quantified by an index m. The effects on the fracture initiation pressure, the fracturing influence range, and displacements of TTHF were analyzed from four aspects, including the homogeneity index of coal, the arrangement angle of branch boreholes, the horizontal stress difference, and the injection rate of the fracturing fluid. The results show that TTHF has a significant effect on the balanced permeability enhancement in coal reservoirs, particularly with strong heterogeneity, and the best permeability enhancement for TTHF is achieved when the branch boreholes are arranged at 45°. The branch boreholes are prefabricated in advance to create a pressure relief area around the injection point, and the hydraulic fracture propagation is affected by the horizontal stress difference only when the fracturing influence range exceeds this area. When the horizontal stress difference increases from 0 to 4 MPa, its fracture initiation pressure increases from 8.93 to 10.86 MPa, with an increase of 21.61%. In addition, the initial stage of fluid injection was found to be crucial for achieving balanced permeability enhancement in TTHF, and a higher injection rate can expand the fracturing influence range. The numerical model has profound implications for the field application of TTHF technology.

Realizing Outstanding Energy Storage Performance in KBT-Based Lead-Free Ceramics via Suppressing Space Charge Accumulation.

The great potential of K1/2Bi1/2TiO3 (KBT) for dielectric energy storage ceramics is impeded by its low dielectric breakdown strength, thereby limiting its utilization of high polarization. This study develops a novel composition, 0.83KBT-0.095Na1/2Bi1/2ZrO3-0.075 Bi0.85Nd0.15FeO3 (KNBNTF) ceramics, demonstrating outstanding energy storage performance under high electric fields up to 425 kV cm-1: a remarkable recoverable energy density of 7.03 J cm-3, and a high efficiency of 86.0%. The analysis reveals that the superior dielectric breakdown resistance arises from effective mitigation of space charge accumulation at the interface, influenced by differential dielectric and conductance behaviors between grains and grain boundaries. Electric impedance spectra confirm the significant suppression of space charge accumulation in KNBNTF, attributable to the co-introduction of Na1/2Bi1/2ZrO3 and Bi0.85Nd0.15FeO3. Phase-field simulations reveal the emergence of a trans-granular breakdown mode in KNBNTF resulting from the mitigated interfacial polarization, impeding breakdown propagation and increasing dielectric breakdown resistance. Furthermore, KNBNTF exhibits a complex local polarization and enhances the relaxor features, facilitating high field-induced polarization and establishing favorable conditions for exceptional energy storage performance. Therefore, the proposed strategy is a promising design pathway for tailoring dielectric ceramics in energy storage applications.

Optimizing Output Power Density in Lead-Free Energy-Harvesting Piezoceramics with an Entropy-Increasing Polymorphic Phase Transition Structure.

It is an urgent need to develop lead-free piezoelectric energy harvesters (PEHs) to address the energy dilemma and meet environmental protection requirements. However, the low output power densities limit further promotion of lead-free PEHs for use in daily life. Here, an entropy-increasing strategy is proposed to achieve an increased output power density of 819 µW/cm3 in lead-free potassium sodium niobate (KNN)-based piezoceramics by increasing the configuration entropy and realizing nearly two times the growth compared with low-entropy counterparts. Evolution of the energy-harvesting performance with increasing configuration entropy is demonstrated systematically, and the excellent energy-harvesting properties achieved are attributed to the enhanced lattice distortion, the flexible polarization configuration, and the high-density randomly distributed nanodomains with the entropy-increasing effect. Moreover, excellent vibration fatigue resistance and variable temperature output power characteristics were also realized in the PEH prepared by the proposed entropy-increasing material. The significant enhancement of the comprehensive energy-harvesting performance demonstrates that the construction of KNN-based ceramics with high configuration entropy represents an effective and convenient strategy to enable design of high-performance piezoceramics and thus promotes the development of advanced PEHs.

Significantly Enhanced Poling Efficiency of Piezocomposites by Tuning Resistivity of a Polymer Matrix.

Although the ability to convert biomechanical vibrations into electric energy has been demonstrated in organic-inorganic piezocomposites, it is challenging to improve their piezoelectric properties owing to insufficient electric field poling. Here, we propose a facile and effective approach to enhance the poling efficiency of a barium calcium zirconate titanate/polydimethylsiloxane (BCZT/PDMS) composite by introducing copper nanowires (Cu NWs) to tune the resistivity of the PDMS matrix. The Cu NW-modified PDMS weakens the resistivity mismatch between the BCZT filler and the PDMS matrix, allowing a higher poling electric field to be applied to the BCZT filler during poling. As a result, the BCZT/Cu-PDMS piezocomposite exhibited a high piezoelectric quality factor (d33 × g33) of 2.58 pm2/N, which was about 7 times higher than that of BCZT/PDMS (d33 × g33 = 0.38 pm2/N). Moreover, BCZT/Cu-PDMS showed a much higher power density (3.18 µW/cm2) and a faster charging capability. This composite approach of introducing metal nanowires can be considered as a generic poling-improvement method that can be extended to other organic-inorganic piezocomposite systems.

Enhanced Piezo-Photocatalytic Performance of Na0.5Bi4.5Ti4O15 by High-Voltage Poling.

The internal electric field within a piezoelectric material can effectively inhibit the recombination of photogenerated electron-hole pairs, thus serving as a means to enhance photocatalytic efficiency. Herein, we synthesized a Na0.5Bi4.5Ti4O15 (NBT) catalyst by the hydrothermal method and optimized its catalytic performance by simple high-voltage poling. When applying light and mechanical stirring on a 2 kV mm-1 poled NBT sample, almost 100% of Rhodamine B solution could be degraded in 120 min, and the reaction rate constant reached as high as 28.36 × 10-3 min-1, which was 4.2 times higher than that of the unpoled NBT sample. The enhanced piezo-photocatalytic activity is attributed to the poling-enhanced internal electric field, which facilitates the efficient separation and transfer of photogenerated carriers. Our work provides a new option and idea for the development of piezo-photocatalysts for environmental remediation and pollutant treatment.

ZNRF2 as an oncogene is transcriptionally regulated by CREB1 in breast cancer models.

E3 ubiquitin ligase Zinc and Ring Finger 2 (ZNRF2) has been demonstrated to be engaged in the development of multiple cancers. Nevertheless, the function of ZNRF2 in breast cancer (BC) still unclear. In this work, we firstly analyzed the differentially expressed genes in BC by bioinformatics and found that ZNRF2 was highly expressed in BC. Consistently, we further confirmed that ZNRF2 was upregulated in BC tissues compared with adjacent normal tissues, and this was positively correlated with the poor prognosis and the higher pathological grades of patients with BC. Functional assays performed on HCC1937 and MCF-7 cells indicated that silencing of ZNRF2 suppressed cell proliferation, as evidenced by the decrease in the expression of cyclin A, PCNA and cyclin D1. Flow cytometry and Hoechst staining showed that knockdown of ZNRF2 induced cell apoptosis, which was verified by the upregulation of apoptosis genes such as Bax, cleaved PARP and Bim. ZNRF2 knockdown also inhibited in vivo tumor growth. But, instead, ZNRF2-overexpressed BC cells exhibited obvious malignant phenotypes. Additionally, we observed that cAMP response element binding protein 1 (CREB1) directly bound to the promoter sequence of ZNRF2 and thus activating its transcription, suggesting that ZNRF2 is transcriptionally regulated by CREB1. Additionally, ZNRF2 knockdown could reverse the proliferation-promoting action of CREB1 on BC cells, Hence, this study demonstrated that ZNRF2 might serve as a prospective therapeutic target for BC.

Oral microbial dysbiosis in patients with periodontitis and chronic obstructive pulmonary disease.

Background: Oral microbiota is closely related to the homeostasis of the oral cavity and lungs. To provide potential information for the prediction, screening, and treatment strategies of individuals, this study compared and investigated the bacterial signatures in periodontitis and chronic obstructive pulmonary disease (COPD). Materials and methods: We collected subgingival plaque and gingival crevicular fluid samples from 112 individuals (31 healthy controls, 24 patients with periodontitis, 28 patients with COPD, and 29 patients with both periodontitis and COPD). The oral microbiota was analyzed using 16S rRNA gene sequencing and diversity and functional prediction analysis were performed. Results: We observed higher bacterial richness in individuals with periodontitis in both types of oral samples. Using LEfSe and DESeq2 analyses, we found differentially abundant genera that may be potential biomarkers for each group. Mogibacterium is the predominant genus in COPD. Ten genera, including Desulfovibrio, Filifactor, Fretibacterium, Moraxella, Odoribacter, Pseudoramibacter Pyramidobacter, Scardovia, Shuttleworthia and Treponema were predominant in periodontitis. Bergeyella, Lautropia, Rothia, Propionibacterium and Cardiobacterium were the signature of the healthy controls. The significantly different pathways in the Kyoto Encyclopedia of Genes and Genomes (KEGG) between healthy controls and other groups were concentrated in genetic information processing, translation, replication and repair, and metabolism of cofactors and vitamins. Conclusions: We found the significant differences in the bacterial community and functional characterization of oral microbiota in periodontitis, COPD and comorbid diseases. Compared to gingival crevicular fluid, subgingival plaque may be more appropriate for reflecting the difference of subgingival microbiota in periodontitis patients with COPD. These results may provide potentials for predicting, screening, and treatment strategies for individuals with periodontitis and COPD.

Interface modified BTO@PS-co-mah/PS composite dielectrics with enhanced breakdown strength and ultralow dielectric loss.

Dielectrics of the polymer-matrix composite are considered to present combined advantages from both the polymer matrix and inorganic fillers. However, the breakdown strength, as well as energy density, is not effectively enhanced due to the poor compatibility between the organic and inorganic components. Herein, polymer composites derived from polystyrene (PS) and barium titanate (BTO) are proposed and beneficial interface modification by poly(styrene-co-maleic anhydride) (PS-co-mah) is conducted to improve compatibility between the inorganic filler and polymer matrix. The results show that the BTO@PS-co-mah/PS composites, in which the interfacial layer of PS-co-mah would undergo chemical reactions with the aminated BTO and blend PS matrix with excellent physical compatibility, exhibit enhanced breakdown strength and declined dielectric loss compared with both pure PS and BTO/PS without interfacial modulation. Particularly, the BTO@PS-co-mah/PS composite with 5 wt% filler content indicates optimized performance with an E b of 507 MV m-1 and tan δ of 0.085%. It is deduced that the deep energy traps introduced by the PS-co-mah layer would weaken the local electric field and suppress the space charge transporting so as to optimize the performance of composites. Consequently, the interfacial-modified BTO@PS-co-mah/PS would present great potential for applications, such as film capacitors.

Two-Step Regulation Strategy Improving Stress Transfer and Poling Efficiency Boosts Piezoelectric Performance of 0-3 Piezocomposites.

The rapid development of flexible micropower electronics has aided the opportunity for the broader application of flexible piezoelectric composites (PCs) but has also led to higher requirements for their power generation. Among them, 0-3 PCs with embedded zero-dimension piezoparticle fillers, although low cost and easy to prepare, suffer from suboptimal output performance because of inherent structural defects. In this work, the voltage output was increased from 3.4 to 12.7 V under a force of 7 N, through first-step regulation by aligning the KNbO3 (KN) particles in the polydimethylsiloxane (PDMS) matrix; then, a significantly enhanced current output (from 0.7 to 4.5 µA) through second-step regulation by introducing copper nanorods (Cu NRs) interspersed in the gaps between the KN chains. Consequently, the proposed PC exhibits much higher power density, 37.3 µW/cm2, than that of random KN/PDMS and thus shows good potential for high-performance, flexible piezoelectric energy harvesters.

Removal Performance and Mechanism of Benzo(b)Fluorathene Using MnO2 Nanoflower/Graphene Oxide Composites.

High-ring polycyclic aromatic hydrocarbons (PAHs, Benzo[b]fluorathene (BbFA), etc.) are difficult to biodegrade in the water environment. To address this issue, an innovative method for the preparation of MnO2 nanoflower/graphene oxide composite (MnO2 NF/GO) was proposed for adsorption removal of BbFA. The physicochemical properties of MnO2 NF/GO were characterized by SEM, TEM, XRD, and N2 adsorption/desorption and XPS techniques. Results show that the MnO2 NF/GO had well-developed specific surface area and functional groups. Batch adsorption experiment results showed that adsorption capacity for BbFA was 74.07 mg/g. The pseudo-second-order kinetic model and Freundlich isotherm model are fitted well to the adsorption data. These show electron-donor-acceptor interaction; especially π-π interaction and π complexation played vital roles in BbFA removal onto MnO2 NF/GO. The study highlights the promising potential adsorbent for removal of PAHs.

Multiscale Heterogeneity Strategy in Piezoceramics for Enhanced Energy Harvesting Performances.

Piezoelectric energy harvesters (PEHs) with piezoceramics as the core can convert low-frequency vibration energy that is ubiquitous in the environment into electrical energy and are at the frontier of research in the field of energy. The high piezoelectric charge coefficient (d) together with the large piezoelectric voltage coefficient (g) are essential for enhancing the energy harvesting performances of PEHs working on a nonresonant state. However, conventional doping and solid solution design strategies lead to the same increase or decrease trend of d and dielectric permittivity ε, making it difficult to obtain a high g value because g = d/ε. Herein, exceptionally well-balanced performances of high d and large g are achieved simultaneously in modified Pb(Zr, Ti)O3(PZT)-based ceramics via a multiscale heterogeneity strategy, which involves coordination among the defect dipole, hierarchical domain, and composite. The electromechanical parameters of the optimal specimen are not only superior to those of many state-of-the-art commercial counterparts but also exhibit good thermal stability. Most importantly, the assembled PEH with the optimal specimen shows excellent variable temperature power generation characteristics. This work provides a paradigm for building PEH material through a multiscale heterogeneity strategy, expected to benefit a wide range of electromechanical coupling materials.

Flexible piezoelectric energy harvester with an ultrahigh transduction coefficient by the interconnected skeleton design strategy.

Based on the strong demand for self-powered wearable electronic devices, flexible piezoelectric energy harvesters (FPEHs) have recently attracted much attention. A polymer-based piezocomposite is the core of an FPEH and its transduction coefficient (d33×g33) is directly related to the material's power generation capacity. Unfortunately, the traditional 0-3 type design method generally causes a weak stress transfer and poor dispersion of the filler in the polymer matrix, making it difficult to obtain a high d33×g33. In this work, a unique interconnected skeleton design strategy has been proposed to overcome these shortcomings. By using the freeze-casting method, an ice-templated 2-2 type composite material has been constructed with the popular piezoelectric relaxor 0.2Pb(Zn1/3Nb2/3)O3-0.8Pb(Zr1/2Ti1/2)O3 (PZN-PZT) as the filler and PDMS as the polymer matrix. Both the theoretical simulation and the experimental results revealed a remarkable enhancement in the stress transfer ability and piezoelectric response. In particular, the 2-2 type piezocomposite has an ultrahigh transduction coefficient of 58 213 × 10-15 m2 N-1, which is significantly better than those of previously reported composite materials, and even textured piezoceramics. This work provides a promising paradigm for the development of high-performance FPEH materials.

Flexible Piezoelectric Energy Harvester with Extremely High Power Generation Capability by Sandwich Structure Design Strategy.

In order to achieve a high-performance flexible piezoelectric energy harvester (FPEH), a unique sandwich structure, that is, a PVDF film filled with FeTiNbO6 (FTN) semiconductor particles as an intermediate layer and a pure PVDF film as an upper and lower barrier layer, has been designed, and the corresponding PVDF-FTN/PVDFx-PVDF (P-FTNx-P) compact composite has been prepared by hot-pressing technology. The special sandwich structure combined with the introduction of FTN particles is beneficial to enhance the interfacial polarization and the content of the electroactive phase in PVDF. Together with the maximum piezoelectric voltage coefficient and the moderate Young's modulus, the P-FTN15%-P FPEH exhibited the optimal energy-harvesting performance with a high power density of 110 µW/cm3 and a large charge density of 75 µC/m2 in cantilever mode. The outstanding design in this work is expected to provide a new way for the development of high-performance FPEH materials.

High performance piezocomposites for flexible device application.

Flexible piezocomposites have emerged as promising materials for highly durable wearable devices. Here, we propose a new design strategy, namely particle alignment engineering, to develop high performance flexible piezocomposites by dielectrophoresis (DEP). An ultrahigh piezoelectric voltage coefficient (g33) of 600 × 10-3 V m N-1 is achieved by a composite of (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 (BCZT) particles aligned in a polydimethylsiloxane (PDMS) matrix. To the best of our knowledge, this g33 value is by far the highest ever achieved in piezocomposites. The significantly improved poling electric voltage applied to the BCZT particles and hugely enhanced stress-transfer capability of the aligned composite synergistically contribute to the record-high piezoelectric response in flexible piezocomposites. The fabricated flexible piezoelectric touch sensor and wearable keyboard possess an excellent sensitivity and cycling stability, which demonstrate a promising strategy for exploring high performance piezocomposites for flexible device application.

Boosting energy harvesting performance in (Ba,Ca)(Ti,Zr)O3 lead-free perovskites through artificial control of intermediate grain size.

In this study, (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCTZ) lead-free ceramics with enhanced energy density were prepared by two-step sintering. All ceramics fall into the rhombohedral-orthorhombic-tetragonal (R-O-T) phase boundary near room temperature, and a dense microstructure with an intermediate grain size was observed. The enhanced piezoelectric and energy harvesting properties were attained over a wide grain size range of 10-15 µm, benefiting from the construction of the R-O-T phase boundary. Most interestingly, the maximum values of d33 and d33 × g33 (530 pC N-1 and 9720 × 10-15 m2 N-1) can be achieved at 1500/1350 °C with a grain size of 13.7 µm. The interpretation of the underlying mechanism related to domain and defect engineering has been investigated systematically. Furthermore, a high output power of 99 µW and an energy conversion efficiency of 10% were obtained at a simple cantilever energy harvester fabricated from a 1500/1350 °C specimen under an acceleration of 1.0g, making the current system very promising for piezoelectric energy harvesting applications.

Composition-induced phase evolution and high strain response in Ba(Zn1/3Nb2/3)O3-modified (Bi0.5Na0.5)TiO3-based lead-free ferroelectrics.

In this work, a paraelectric complex perovskite Ba(Zn1/3Nb2/3)O3 (BZN) was introduced into the morphotropic boundary composition (Bi0.5Na0.5)0.93Ba0.07TiO3 (BNBT) to modulate the phase structure and electrical properties as well as the field-induced strain behavior. Using a columbite route, the ceramics with pure perovskite structure were successfully fabricated. The structure and electrical measurements showed that the introduction of BZN into BNBT results in the decrease of the rhombohedrality 90-γ, and promotes the evolution from ferroelectric to antiferroelectric (AFE) relaxor. Besides, the introduction of BZN induces the volume increase and dimension reduction of the nanosized AFE relaxor domains. A large field-induced strain of 0.39% with good stability against frequency, field, and temperature was obtained at the BNZ addition of composition x = 0.01, which locates at the critical composition boundary between ferroelectric state and AFE relaxor state.

Improving Dielectric Properties of PVDF Composites by Employing Surface Modified Strong Polarized BaTiO3 Particles Derived by Molten Salt Method.

BaTiO3/polyvinylidene fluoride (BT/PVDF) is the extensive reported composite material for application in modern electric devices. However, there still exists some obstacles prohibiting the further improvement of dielectric performance, such as poor interfacial compatibility and low dielectric constant. Therefore, in depth study of the size dependent polarization and surface modification of BT particle is of technological importance in developing high performance BT/PVDF composites. Here, a facile molten-salt synthetic method has been applied to prepare different grain sized BT particles through tailoring the calcination temperature. The size dependent spontaneous polarizationof BT particle was thoroughly investigated by theoretical calculation based on powder X-ray diffraction Rietveld refinement data. The results revealed that 600 nm sized BT particles possess the strong polarization, ascribing to the ferroelectric size effect. Furthermore, the surface of optimal BT particles has been modified by water-soluble polyvinylprrolidone (PVP) agent, and the coated particles exhibited fine core-shell structure and homogeneous dispersion in the PVDF matrix. The dielectric constant of the resulted composites increased significantly, especially, the prepared composite with 40 vol % BT loading exhibited the largest dielectric constant (65, 25 °C, 1 kHz) compared with the literature values of BT/PVDF at the same concentration of filler. Moreover, the energy storage density of the composites with tailored structure was largely enhanced at the low electric field, showing promising application as dielectric material in energy storage device. Our work suggested that introduction of strong polarized ferroelectric particles with optimal size and construction of core-shell structured coated fillers by PVP in the PVDF matrix are efficacious in improving dielectric performance of composites. The demonstrated approach can also be applied to the design and preparation of other polymers-based nanocomposites filled with ferroelectric particles to achieve desirable dielectric properties.

Potential mechanisms underlying the Runx2 induced osteogenesis of bone marrow mesenchymal stem cells.

Bone marrow derived mesenchymal stem cells (BM-MSCs) belong a type of pluripotent stem cells and can be induced to differentiate into osteoblasts (OB). Runt-related transcription factor 2 (Runx2) is an osteogenesis specific transcription factor and plays an important role in osteogenesis of BM-MSCs. It can promote the expression of osteogenesis related genes, regulate cell cycle progression, improve bone microenvironment and affect functions of chondrocytes and osteoclasts, which have involvement of a large amount of signal molecules including TGF-ß, BMP, Notch, Wnt, Hedgehog, FGF and microRNA. In this paper, we summarize the mechanisms underlying the Runx2 induced osteogenesis of BM-MSCs.

[Smokeless tobacco extract affects biological properties of the pre-osteoblast cell line MC3T3-E1 ].

OBJECTIVE: To investigate the effects of smokeless tobacco extract (STE) on biological properties of osteoblast, and to identify possible pathological mechanisms of osseointegration. METHODS: MC3T3-E1 Sub-clone 14 cells were cultured in the presence of STE at 0 (control group),0. 01,0. 1,1,5,10 g/L. The cell proliferation was measured by MTT assay 1 d, 3 d, 5 d, and 7 d after exposure. The F-actin cytoskeleton of MC3T3 was stained with Rhodamine and DAPI, and then examined under a confocal laser scanning microscope 24 h after exposure to STE. The mRNA expressions of interleukin-6 (IL-6) and core-binding factor αl(Cbfαl) were quantified by real- time PCR (RT-qPCR) 48 h after exposure to STE. RESULTS: The MTT assay showed that 0. 01-10 g/L STE inhibited MC3T3 proliferation (P<0. 05). Prolonged time enabled 5-10 g/L STE to inhibit MC3T3 proliferation (P<0. 05). Network structure in F-actin cytoskeleton was demonstrated in the controls. In the cells exposed to STE, F-actin cytoskeleton started to change with disruptive structures. As the concentration of STE increased, the changes became more significant. STE increased the mRNA expression of IL-6 at the concentration of 5 g/L and 10 g/L (P<0.05), decreased the mRNA expression of Cbfα1 at the concentration of 0. 1-10 g/L (PO<0. 05). CONCLUSION: Tobacco may inhibit osteoblast proliferation, destroy F-actin cytoskeleton structure, increase the mRNA expression of IL-6 and decrease the mRNA expression of Cbfα1, and inhibit cell differentiation and adhesion accordingly. Smoking is a disadvantage to osseointegration.

[Effects of tobacco on rat gingival fibroblats attaching to titanium].

PURPOSE: The study was designed to observe the effects of the smokeless tobacco extract(ST) on the attachment,morphology,structure and proliferation of rat gingival fibroblasts(RGFs) to titanium in vitro. METHODS: RGFs were obtained from explants of rat normal gingival tissues by using tissue-explant technique.The origin of cells was identified by immunochemistry of vimentin and cytokeratin. RGFs to titanium were cultured in the presence of ST at various concentration,the attachment and growth of cells attached to titanium were measured by MTT method, immunofluorescence was used to detect and analyze the shapes of RGFs attached to titanium.Statistical analysis was performed using SPSS13.0 software package for one-way ANOVA. RESULTS: Immunochemical study showed that vimentin was expressed in RGFs while cytokeratin was negative,which indicated that RGFs were originated from mesoblastoma.With the increasing of ST concentration,the attachment,spreading shape and proliferation of RGFs in all groups decreased in a concentration-dependent manner.The difference between ST group and control group was statistically significant(P<0.05). CONCLUSIONS: ST can inhibit the attachment,spreading shape and proliferation of RGFs, suggesting that smoking may have influence on the long result of oral implant operation.