Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultiv...Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consum展开更多
The strength of structural loess consists of the shear strength and tensile strength. In this study, the stress path, the failure envelope of principal stress （ Kf line）, and the strength failure envelope of structu...The strength of structural loess consists of the shear strength and tensile strength. In this study, the stress path, the failure envelope of principal stress （ Kf line）, and the strength failure envelope of structurally intact loess and remolded loess were analyzed through three kinds of tests： the tensile strength test, the uniaxial compressive strength test, and the conventional triaxial shear strength test. Then, in order to describe the tensile strength and shear strength of structural loess comprehensively and reasonably, a joint strength formula for structural loess was established. This formula comprehensively considers tensile and shear properties. Studies have shown that the tensile strength exhibits a decreasing trend with increasing water content. When the water content is constant, the tensile strength of the structurally intact soil is greater than that ofremolded soil. In the studies, no loss of the originally cured cohesion in the structurally intact soil samples was observed, given that the soil samples did not experience loading disturbance during the uniaxial compressive strength test, meaning there is a high initial structural strength. The results of the conventional triaxial shear strength test show that the water content is correlated with the strength of the structural loess. When the water content is low, the structural properties are strong, and when the water content is high, the structural properties are weak, which means that the water content and the ambient pressure have significant effects on the stress-strain relationship of structural loess. The established joint strength formula of structural loess effectively avoids overestimating the role of soil tensile strength in the traditional theory of Mohr-Coulomb strength.展开更多
Background:The downstaging of hepatocellular carcinoma(HCC)has been confirmed to benefit liver transplantation(LT)patients whose tumors are beyond the transplantation criteria.Milan criteria(MC),a tumor size and numbe...Background:The downstaging of hepatocellular carcinoma(HCC)has been confirmed to benefit liver transplantation(LT)patients whose tumors are beyond the transplantation criteria.Milan criteria(MC),a tumor size and number-based assessment,is currently used as the endpoint in these patients.However,many studies believe that tumor biological behavior should be added to the evaluation criteria for downstaging efficacy.Hence,this study aimed to explore the feasibility of Hangzhou criteria(HC),which introduced tumor grading and alpha-fetoprotein in addition to tumor size and number,as an endpoint of downstaging.Methods:We performed a multicenter and retrospective study of 206 patients accepted locoregional therapy(LRT)as downstaging/bridge treatment prior to LT in three centers of China.Results:Recipients were divided into four groups:failed downstaging to the HC(group A,n=46),successful downstaging to the HC(group B,n=30),remained within the HC all the time(group C,n=113),and tumor progressed(group D,n=17).The 3-year HCC recurrence probabilities of groups B and C were not significantly different(10.3%vs.11.6%,P=0.87).The HCC recurrent rate was significantly higher in group A(52.3%)compared with that in group B/C(P<0.05).Seven patients(7/76,9.2%)whose tumor exceeded the the HC were successfully downstaged to the MC,and 39.5%(30/76)to the the HC.In group B,23 patients remained beyond the MC and their survivals were as well as those of patients within the MC.Conclusions:Compared to the MC,HC downstaging criteria can give more HCC patients access to LT and furthermore,the outcome of these patients is the same as those matching MC downstaging criteria.Hangzhou downstaging criteria therefore is applicable in clinical practice.展开更多
AIM： To investigate the possible mechanism for HBV X gene to induce apoptosis of hepatocyte HL-7702 cells.METHODS： HBV X gene eukaryon expression vector pcDNA3-X was established and transfected into HL-7702 cells by...AIM： To investigate the possible mechanism for HBV X gene to induce apoptosis of hepatocyte HL-7702 cells.METHODS： HBV X gene eukaryon expression vector pcDNA3-X was established and transfected into HL-7702 cells by lipid-mediated transfection, including transient and stable transfection. Positive clones were screened by incubating in the selective medium with 600 μg/mL G418 and named HL-7702/HBV-encoded X protein （HBx） cells. The expressions of Fas/FasL, Bax/Bcl-2, and c-myc mRNA were measured by semi-quantitative RT-PCR in HL-7702/HBx and control group, respectively.RESULTS： RT-PCR analysis confirmed that HBV X gene was transfected into HL-7702 cells successfully. By semiquantitative RT-PCR analysis, Bax and c-myc mRNA levels in HL-7702/HBx cells of transient transfection were significantly higher than those in control, FasL and c-myc mRNA levels in HL-7702/HBx cells of stable transfection were significantly higher than those in control, whereas the Bcl-2 mRNA levels in HL-7702/HBx cells of transient and stable transfection were significantly lower than thosein control.CONCLUSION： HBV X gene may promote the apoptosis of hepatocytes by regulating the expressions of Fas/FasL, Bax/Bcl-2, and c-myc gene in a dose-dependent manner.展开更多
AIM： To investigate the effect of hepatitis B virus （HBV） X gene on apoptosis and expressions of apoptosis factors in X gene-transfected HepG2 cells.METHODS： The HBV X gene eukaryon expression vector pcDNA3-X was ...AIM： To investigate the effect of hepatitis B virus （HBV） X gene on apoptosis and expressions of apoptosis factors in X gene-transfected HepG2 cells.METHODS： The HBV X gene eukaryon expression vector pcDNA3-X was transiently transfected into HepG2 cells by lipid-media transfection. Untransfected HepG2 and HepG2 transfected with pcDNA3 were used as controls. Expression of HBx in HepG2 was identified by RT-PCR. MTT and TUNEL were employed to measure proliferation and apoptosis of cells in.three groups. Semi-quantified RT-PCR was used to evaluate the expression levels of Fas/FasL, Bax/Bcl-xL, and c-myc in each group.RESULTS： HBV X gene was transfected into HepG2 cells successfully. RT-PCR showed that HBx was only expressed in HepG2/pcDNA3-X cells, but not expressed in HepG2 and HepG2/pcDNA3 cells. Analyzed by MTT, cell proliferationcapacity was obviously lower in HepG2/pcDNA3-X cells （0.08910±0.003164） than in HepG2 （0.14410±0.004927） and HepG2/pcDNA3 cells （0.12150±0.007159） （P〈0.05 and P〈0.01）. Analyzed by TUNEL, cell apoptosis was much more in HepG2/pcDNA3-X cells （980/2 000） than HepG2 （420/2 000）, HepG2/pcDNA3 cells （520/2 000） （P〈0.05 and P〈0.01）. Evaluated by semi-quantified RT-PCR, the expression level of Fas/FasL was significantly higher in HepG2 cells transfected with HBx than in HepG2 and HepG2/pcDNA3 cells （P〈0.05 and P〈0.01）. Bax/Bcl-xL expression level was also elevated in HepG2/pcDNA3-X cells （P〈0.05 and P〈0.01）. Expression of c-myc was markedly higher in HepG2/pcDNA3-X cells than in HepG2 and HepG2/pcDNA3 cells （P〈0.05 and P〈0.01）.CONCLUSION： HBV X gene can impair cell proliferation capacity, improve cell apoptosis, and upregulate expression of apoptosis factors. The intervention of HBV X gene on the expression of apoptosis factors may be a possible mechanism responsible for the change in cell apoptosis and proliferation.展开更多
Microglia-mediated inflammatory responses have been shown to play a crucial role in Parkinson’s disease. In addition, exosomes derived from mesenchymal stem cells have shown anti-inflammatory effects in the treatment...Microglia-mediated inflammatory responses have been shown to play a crucial role in Parkinson’s disease. In addition, exosomes derived from mesenchymal stem cells have shown anti-inflammatory effects in the treatment of a variety of diseases. However, whether they can protect neurons in Parkinson’s disease by inhibiting microglia-mediated inflammatory responses is not yet known. In this study, exosomes were isolated from human umbilical cord mesenchymal stem cells and injected into a 6-hydroxydopamine-induced rat model of Parkinson’s disease. We found that the exosomes injected through the tail vein and lateral ventricle were absorbed by dopaminergic neurons and microglia on the affected side of the brain, where they repaired nigral-striatal dopamine system damage and inhibited microglial activation. Furthermore, in an in vitro cell model, pretreating lipopolysaccharide-stimulated BV2 cells with exosomes reduced interleukin-1β and interleukin-18 secretion, prevented the adoption of pyroptosis-associated morphology by BV2 cells, and increased the survival rate of SH-SY5Y cells. Potential targets for treatment with human umbilical cord mesenchymal stem cells and exosomes were further identified by high-throughput microRNA sequencing and protein spectrum sequencing. Our findings suggest that human umbilical cord mesenchymal stem cells and exosomes are a potential treatment for Parkinson’s disease, and that their neuroprotective effects may be mediated by inhibition of excessive microglial proliferation.展开更多
Background Our previous studies have indicated that the beneficial effects of grafting neural stem cells （NSCs） overexpressing glial cell line-derived neurotrophic factor （GDNF） in rats after stroke. However, the ...Background Our previous studies have indicated that the beneficial effects of grafting neural stem cells （NSCs） overexpressing glial cell line-derived neurotrophic factor （GDNF） in rats after stroke. However, the underlying mechanisms are highly debatable. In this study, we investigated whether neurogenesis, Akt, and extracellular signal- regulated kinase 1/2 （Erkl/2） signaling were involved in this process. Methods Transient ischemic stroke were induced by occluding middle cerebral artery for 2 hours and reperfusion. At 3 days after reperfusion, GDNF/NSCs, NSCs, and vehicle were administered. Immunohistochemical staining was used to evaluate neurogenesis by nestin antibody; phosphorylation of Akt and Erkl/2 was investigated by Western blotting analysis. Results Transplantation of GDNF/NSCs and NSCs significantly increased nestin-positive cells compared to control group （vehicle） from 1 to 7 weeks after reperfusion, and GDNF/NSCs showed stronger effect than NSCs at 2 and 3 weeks after reperfusion. Meanwhile, enhanced phosphorylation level of Erkl/2 was observed in the GDNF/NSCs and NSCs groups compared with control group, and phosphorylation level of Erkl/2 in GDNF/NSCs group was remarkably higher than that of NSCs group at any given time. In contrast, expression of mitogen-activated protein kinase phosphatase-1 （MKP-1）, known as inhibitor of Erkl/2 signaling, was significantly decreased in the GDNF/NSCs and NSCs groups compared with the control group. Moreover, much enhanced and prolonged phosphorylation level of Akt of GDNF/NSCs group was detected compared with control and NSCs group. Conclusion Grafting GDNF/NSCs enhances neurogenesis and activates Akt and Erkl/2 signaling, that may provide the potential for GDNF/NSCs in stroke treatment.展开更多
Designing a heterojunction photocatalyst to improve the separation efficiency of photogenerated electrons and holes is of great significance to improve the hydrogen production efficiency.In this work,we report a ratio...Designing a heterojunction photocatalyst to improve the separation efficiency of photogenerated electrons and holes is of great significance to improve the hydrogen production efficiency.In this work,we report a rational design to grow ZnIN_(2)S_(4)on Mo-MOF-derived N-doped C-coated MoO_(2)(MOZIS),and it has excellent photocatalytic hydrogen production with triethanolamine(TEOA)as sacrificial agent.N-doped C improves the electron transport efficiency between MoO_(2)and ZnIN_(2)S_(4)·The systematic study shows that MOZIS has good properties to promote the effective separation and transfer of photocatalytic charges,which is attributed to the tight contact interface and good energy band structure between MoO_(2)and ZnlN_(2)S_(4).The optimized nanocomposites have a high hydrogen production efficiency of 10.89 mmol·g^(-1)(4 h)under visible light.MOF-derived N-doped C-coated MoO_(2)is an effective strategy to improve the photocatalytic hydrogen production efficiency of ZnIN_(2)S_(4).展开更多
Transplantation of neural stem cells(NSCs) can protect neurons in animal stroke models;however, their low rates of survival and neuronal differentiation limit their clinical application. Glial niches, an important loc...Transplantation of neural stem cells(NSCs) can protect neurons in animal stroke models;however, their low rates of survival and neuronal differentiation limit their clinical application. Glial niches, an important location of neural stem cells, regulate survival, proliferation and differentiation of neural stem cells. However, the effects of activated glial cells on neural stem cells remain unclear. In the present study, we explored the effects of activated astrocytes and microglia on neural stem cells in vitro stroke models. We also investigated the effects of combined transplantation of neural stem cells and glial cells after stroke in rats. In a Transwell co-culture system, primary cultured astrocytes, microglia or mixed glial cells were exposed to glutamate or H_2O_2 and then seeded in the upper inserts, while primary neural stem cells were seeded in the lower uncoated wells and cultured for 7 days. Our results showed that microglia were conducive to neurosphere formation and had no effects on apoptosis within neurospheres, while astrocytes and mixed glial cells were conducive to neurosphere differentiation and reduced apoptosis within neurospheres, regardless of their pretreatment. In contrast, microglia and astrocytes induced neuronal differentiation of neural stem cells in differentiation medium, regardless of their pretreatment, with an exception of astrocytes pretreated with H_2O_2. Rat models of ischemic stroke were established by occlusion of the middle cerebral artery. Three days later, 5 × 10~5 neural stem cells with microglia or astrocytes were injected into the right lateral ventricle. Neural stem cell/astrocyte-treated rats displayed better improvement of neurological deficits than neural stem cell only-treated rats at 4 days after cell transplantation. Moreover, neural stem cell/microglia-, and neural stem cell/astrocyte-treated rats showed a significant decrease in ischemic volume compared with neural stem celltreated rats. These findings indicate that microglia and astrocytes exert different e展开更多
To investigate the impact of an opening and joints with different inclination angles on the mechanical response behavior,the energy evolution characteristics,and distribution law of granite specimens,uniaxial loading ...To investigate the impact of an opening and joints with different inclination angles on the mechanical response behavior,the energy evolution characteristics,and distribution law of granite specimens,uniaxial loading tests were performed on the parallel jointed rock samples with an opening.Results indicated an initial decreasing trend of the strength and deformation parameters,which later increases with increased inclination angle,reaching minimum values when the inclination angle is 45°.Evolution curves of the elastic strain energy and dissipated energy with strain of the samples showed step-like gradual mutation characteristics.The peak total energy,peak elastic strain energy,peak dissipated energy,and total input energy during the failure of the samples showed significant nonlinear characteristics with increasing inclination angle.The opening and joints as well as the change of the inclination angle had significant influences on the proportion of the elastic strain energy of the samples prior to the peak,resulting in the difference of the distribution law of input energy.Moreover,the energy mechanism of the sample failure was discussed.Results showed that the energy release was the internal cause of the sudden destruction of the entire rock mass.展开更多
In this study, we obtained information from twenty-one measurement points on the stress magnitudes and orientations of a gold mine in the Ludong area. We used the overcoring technique with an improved hollow inclusion...In this study, we obtained information from twenty-one measurement points on the stress magnitudes and orientations of a gold mine in the Ludong area. We used the overcoring technique with an improved hollow inclusion strain gauge and then analyzed the distribution characteristics of the in situ stress field. The results indicate that the stress field is characterized by σH > σh > σv and σH > σv > σh(where σH, σh, and σv are the maximum horizontal, minimum horizontal, and vertical principal stresses, respectively). The regional stress field is dominated by horizontal principal stress. The σH, σh, and σv values show a gradual increasing trend with depth. The σH is predominantly oriented in the NWW–SEE or near-EW direction. We also confirmed the correspondence between the measured stress field and the regional geological structure. In addition, based on the measured stress data, we discuss the implications of the in situ stress with respect to fault activity in the mine area.展开更多
Two new sesquiterpenoids,attributable to eudesmane-type（1 and 2,named solajiangxins F and G）,were isolated from the whole plant of Solanum lyratum.Their structures were elucidated on the basis of integrated spectros...Two new sesquiterpenoids,attributable to eudesmane-type（1 and 2,named solajiangxins F and G）,were isolated from the whole plant of Solanum lyratum.Their structures were elucidated on the basis of integrated spectroscopic techniques.In vitro,compounds 1 and 2 were found to show signifcant cytotoxic activity against selected cancer cells,including P-388,HONE-1 and HT-29.展开更多
The localization damage and deformation characteristics of multiple rock in mined-out area under thick soil layer were investigated by acoustic emission （AE）-based physical similar simulation experiment and damage t...The localization damage and deformation characteristics of multiple rock in mined-out area under thick soil layer were investigated by acoustic emission （AE）-based physical similar simulation experiment and damage test combined with the AE theory on rock damage. During different mining courses, the degree of wall rock suffered from mining disturbed process in mined-out area was different, so did the AE density of initial damage and fracture. Some characteristic parameters, including large events, total events, and energy rate, presented fluctuations with temporal and spatial change and take on a certain extent statistic relation. Subsequently, the percent of damage degree was defined and divided into 4 stages, and the localization damage and deformation characteristics of surrounding rock in mined-out area and coal pillars were analyzed quantitatively.展开更多
Excessive dexamethasone (Dex) administrated into pregnant mice during critical periods of palatal development can produce a high incidence of cleft palate. Its mechanisms remain unknown. Vitamin B12 has been shown to ...Excessive dexamethasone (Dex) administrated into pregnant mice during critical periods of palatal development can produce a high incidence of cleft palate. Its mechanisms remain unknown. Vitamin B12 has been shown to antagonize the tera- togenic effects of Dex, which, however, remains controversial. In this study, we investigated the effects of Dex and vitamin B12 on murine embryonic palatal shelf fusion using organ culture of murine embryonic shelves. The explanted palatal shelves on em- bryonic day 14 (E14) were cultured for 24, 48, 72 or 96 h in different concentrations of Dex and/or vitamin B12. The palatal shelves were examined histologically for the morphological alterations on the medial edge epithelium (MEE) and fusion rates among different groups. It was found that the palatal shelves were not fused at 72 h or less of culture in Dex group, while they were completely fused in the control and vitamin B12-treated groups at 72 and 96 h, respectively. The MEE still existed and proliferated. In Dex+vitamin B12 group the palatal shelves were fused at each time point in a similar rate to controls. These results may suggest that Dex causes teratogenesis of murine embryonic palatal shelves and vitamin B12 prevents the teratogenic effect of Dex on palatogenesis on murine embryos in vitro.展开更多
The hydrodynamics of batoid swimming motions is investigated using the three-dimensional simulation of a self-propelled body in still water. The kinematics of batoid swimming is characterized by large amplitude undula...The hydrodynamics of batoid swimming motions is investigated using the three-dimensional simulation of a self-propelled body in still water. The kinematics of batoid swimming is characterized by large amplitude undulations of the pectoral fins while the middle part of the body remains straight. The majority of the thrust is generated by pectoral fins. Linear and quadratic amplitude variations are used for the pectoral fins in analyzing the locomotion of the batoid. Navier-Stokes equations are used to solve the unsteady fluid flow. A user defined function and a dynamic mesh method are applied to track the batoid locomotion. The mean swimming velocities of 1.6 BL/s and 1.3 BL/s are achieved, respectively, with thrust coefficients of 0.13 in and 0.095 in the dynamical simulation, where BL/s is the body length per second. The maximum propulsive efficiency 19% is achieved when the frequency of the undulation is 2.2 Hz in both amplitude variations.展开更多
Metal organic framework(MOF) shows great potential in the research field of photocatalysis,and it is a big challenge to achieve efficient photocatalytic activity.In this work,we have successfully grown two-dimensional...Metal organic framework(MOF) shows great potential in the research field of photocatalysis,and it is a big challenge to achieve efficient photocatalytic activity.In this work,we have successfully grown two-dimensional MOF(2D-MOF) nanosheets on 2D-MOF nanosheets for the first time using a homometallic nodal strategy,and successfully prepared ultrathin nanosheets with tightly bound 2D/2D heterojunctions.2D Ni-BDC nanosheets were used as carriers to grow 2D Ni-TCPP nanosheets on top of them.Ni-TCPP has a high light absorption capacity,thus extending the light absorption range of 2D/2D heterojunctions.The tight coupling of the heterojunction effectively shortens the electron transfer distance,promotes the separation of interracial charges,and improves the photocatalytic activity.Particularly,Ni-BDC/Ni-TCPP-3can achieve to a hydrogen production rate of428.0 μmol·g^(-1),approximately 5.75 times higher than NiBDC and 5.24 times higher than Ni-TCPP,respectively.Thus,2D-MOF/2D-MOF heterojunctions provide a promising strategy for enhancing photocatalytic performance through rational heterostructure design with homometallic node strategy.展开更多
基金financially supported by the National Basic Research Program of China (2011CB100506)the China Agriculture Research System-Wheat (CARS-03-02A)+1 种基金the Knowledge Innovation Program of the Chinese Academy of Sciences (KSCX2-EW-N-08)Research Fund of State Key Laboratory of Soil and Sustainable Agriculture, Nanjing Institute of Soil Science, Chinese Academy of Sciences (Y412201401)
文摘Cropland productivity has been significantly impacted by soil acidification resulted from nitrogen （N） fertilization, especially as a result of excess ammoniacal N input. With decades＇ intensive agricultural cultivation and heavy chemical N input in the Huang-Huai-Hai Plain, the impact extent of induced proton input on soil pH in the long term was not yet clear. In this study, acidification rates of different soil layers in the soil profile （0-120 cm） were calculated by pH buffer capacity （pHBC） and net input of protons due to chemical N incorporation. Topsoil （0-20 cm） pH changes of a long-term fertilization field （from 1989） were determined to validate the predicted values. The results showed that the acid and alkali buffer capacities varied significantly in the soil profile, averaged 692 and 39.8 mmolc kg-1 pH-1, respectively. A significant （P〈0.05） correlation was found between pHRC and the content of calcium carbonate. Based on the commonly used application rate of urea （500 kg N ha-1 yr-1）, the induced proton input in this region was predicted to be 16.1 kmol ha-1 yr-1, and nitrification and plant uptake of nitrate were the most important mechanisms for proton producing and consuming, respectively. The acidification rate of topsoil （0-20 cm） was estimated to be 0.01 unit pH yr-1 at the assumed N fertilization level. From 1989 to 2009, topsoil pH （0-20 cm） of the long-term fertilization field decreased from 8.65 to 8.50 for the PK （phosphorus, 150 kg P205 ha-1 yr-1; potassium, 300 kg K20 ha-1 yr-1; without N fertilization）, and 8.30 for NPK （nitrogen, 300 kg N ha-1 yr-1; phosphorus, 150 kg P2Os ha-1 yr-1; potassium, 300 kg K20 ha -1 yr-1）, respectively. Therefore, the apparent soil acidification rate induced by N fertilization equaled to 0.01 unit pH yr-1, which can be a reference to the estimated result, considering the effect of atmospheric N deposition, crop biomass, field management and plant uptake of other nutrients and cations. As protons could be consum
基金supported by the National Natural Science Foundation of China(Grant No.11072193)the Fundamental Research Funds for the Central Universities(Grant No.2013G1502009)the China Postdoctoral Science Foundation(Grant No.20100481354)
文摘The strength of structural loess consists of the shear strength and tensile strength. In this study, the stress path, the failure envelope of principal stress （ Kf line）, and the strength failure envelope of structurally intact loess and remolded loess were analyzed through three kinds of tests： the tensile strength test, the uniaxial compressive strength test, and the conventional triaxial shear strength test. Then, in order to describe the tensile strength and shear strength of structural loess comprehensively and reasonably, a joint strength formula for structural loess was established. This formula comprehensively considers tensile and shear properties. Studies have shown that the tensile strength exhibits a decreasing trend with increasing water content. When the water content is constant, the tensile strength of the structurally intact soil is greater than that ofremolded soil. In the studies, no loss of the originally cured cohesion in the structurally intact soil samples was observed, given that the soil samples did not experience loading disturbance during the uniaxial compressive strength test, meaning there is a high initial structural strength. The results of the conventional triaxial shear strength test show that the water content is correlated with the strength of the structural loess. When the water content is low, the structural properties are strong, and when the water content is high, the structural properties are weak, which means that the water content and the ambient pressure have significant effects on the stress-strain relationship of structural loess. The established joint strength formula of structural loess effectively avoids overestimating the role of soil tensile strength in the traditional theory of Mohr-Coulomb strength.
基金grants from the National Science and Technology Major Project of China(No.2017ZX10203205)the National Natural Science Founds for Distinguished Young Scholar of China(No.81625003)+1 种基金the State Key Program of National Natural Science Foundation of China(No.81930016)the National Natural Science Foundation of China(No.81902407).
文摘Background:The downstaging of hepatocellular carcinoma(HCC)has been confirmed to benefit liver transplantation(LT)patients whose tumors are beyond the transplantation criteria.Milan criteria(MC),a tumor size and number-based assessment,is currently used as the endpoint in these patients.However,many studies believe that tumor biological behavior should be added to the evaluation criteria for downstaging efficacy.Hence,this study aimed to explore the feasibility of Hangzhou criteria(HC),which introduced tumor grading and alpha-fetoprotein in addition to tumor size and number,as an endpoint of downstaging.Methods:We performed a multicenter and retrospective study of 206 patients accepted locoregional therapy(LRT)as downstaging/bridge treatment prior to LT in three centers of China.Results:Recipients were divided into four groups:failed downstaging to the HC(group A,n=46),successful downstaging to the HC(group B,n=30),remained within the HC all the time(group C,n=113),and tumor progressed(group D,n=17).The 3-year HCC recurrence probabilities of groups B and C were not significantly different(10.3%vs.11.6%,P=0.87).The HCC recurrent rate was significantly higher in group A(52.3%)compared with that in group B/C(P<0.05).Seven patients(7/76,9.2%)whose tumor exceeded the the HC were successfully downstaged to the MC,and 39.5%(30/76)to the the HC.In group B,23 patients remained beyond the MC and their survivals were as well as those of patients within the MC.Conclusions:Compared to the MC,HC downstaging criteria can give more HCC patients access to LT and furthermore,the outcome of these patients is the same as those matching MC downstaging criteria.Hangzhou downstaging criteria therefore is applicable in clinical practice.
基金Supported by the Science and Technology Fund of Fujian Province, No. 99-Z-162
文摘AIM： To investigate the possible mechanism for HBV X gene to induce apoptosis of hepatocyte HL-7702 cells.METHODS： HBV X gene eukaryon expression vector pcDNA3-X was established and transfected into HL-7702 cells by lipid-mediated transfection, including transient and stable transfection. Positive clones were screened by incubating in the selective medium with 600 μg/mL G418 and named HL-7702/HBV-encoded X protein （HBx） cells. The expressions of Fas/FasL, Bax/Bcl-2, and c-myc mRNA were measured by semi-quantitative RT-PCR in HL-7702/HBx and control group, respectively.RESULTS： RT-PCR analysis confirmed that HBV X gene was transfected into HL-7702 cells successfully. By semiquantitative RT-PCR analysis, Bax and c-myc mRNA levels in HL-7702/HBx cells of transient transfection were significantly higher than those in control, FasL and c-myc mRNA levels in HL-7702/HBx cells of stable transfection were significantly higher than those in control, whereas the Bcl-2 mRNA levels in HL-7702/HBx cells of transient and stable transfection were significantly lower than thosein control.CONCLUSION： HBV X gene may promote the apoptosis of hepatocytes by regulating the expressions of Fas/FasL, Bax/Bcl-2, and c-myc gene in a dose-dependent manner.
文摘AIM： To investigate the effect of hepatitis B virus （HBV） X gene on apoptosis and expressions of apoptosis factors in X gene-transfected HepG2 cells.METHODS： The HBV X gene eukaryon expression vector pcDNA3-X was transiently transfected into HepG2 cells by lipid-media transfection. Untransfected HepG2 and HepG2 transfected with pcDNA3 were used as controls. Expression of HBx in HepG2 was identified by RT-PCR. MTT and TUNEL were employed to measure proliferation and apoptosis of cells in.three groups. Semi-quantified RT-PCR was used to evaluate the expression levels of Fas/FasL, Bax/Bcl-xL, and c-myc in each group.RESULTS： HBV X gene was transfected into HepG2 cells successfully. RT-PCR showed that HBx was only expressed in HepG2/pcDNA3-X cells, but not expressed in HepG2 and HepG2/pcDNA3 cells. Analyzed by MTT, cell proliferationcapacity was obviously lower in HepG2/pcDNA3-X cells （0.08910±0.003164） than in HepG2 （0.14410±0.004927） and HepG2/pcDNA3 cells （0.12150±0.007159） （P〈0.05 and P〈0.01）. Analyzed by TUNEL, cell apoptosis was much more in HepG2/pcDNA3-X cells （980/2 000） than HepG2 （420/2 000）, HepG2/pcDNA3 cells （520/2 000） （P〈0.05 and P〈0.01）. Evaluated by semi-quantified RT-PCR, the expression level of Fas/FasL was significantly higher in HepG2 cells transfected with HBx than in HepG2 and HepG2/pcDNA3 cells （P〈0.05 and P〈0.01）. Bax/Bcl-xL expression level was also elevated in HepG2/pcDNA3-X cells （P〈0.05 and P〈0.01）. Expression of c-myc was markedly higher in HepG2/pcDNA3-X cells than in HepG2 and HepG2/pcDNA3 cells （P〈0.05 and P〈0.01）.CONCLUSION： HBV X gene can impair cell proliferation capacity, improve cell apoptosis, and upregulate expression of apoptosis factors. The intervention of HBV X gene on the expression of apoptosis factors may be a possible mechanism responsible for the change in cell apoptosis and proliferation.
基金supported by the Natural Science Foundation of Hebei Province,Nos.18967728D (to XQC),H2021423063 (to HXC)Youth Top Talent Project of Colleges and Universities in Hebei Province,No.BJ2021033 (to HXC)。
文摘Microglia-mediated inflammatory responses have been shown to play a crucial role in Parkinson’s disease. In addition, exosomes derived from mesenchymal stem cells have shown anti-inflammatory effects in the treatment of a variety of diseases. However, whether they can protect neurons in Parkinson’s disease by inhibiting microglia-mediated inflammatory responses is not yet known. In this study, exosomes were isolated from human umbilical cord mesenchymal stem cells and injected into a 6-hydroxydopamine-induced rat model of Parkinson’s disease. We found that the exosomes injected through the tail vein and lateral ventricle were absorbed by dopaminergic neurons and microglia on the affected side of the brain, where they repaired nigral-striatal dopamine system damage and inhibited microglial activation. Furthermore, in an in vitro cell model, pretreating lipopolysaccharide-stimulated BV2 cells with exosomes reduced interleukin-1β and interleukin-18 secretion, prevented the adoption of pyroptosis-associated morphology by BV2 cells, and increased the survival rate of SH-SY5Y cells. Potential targets for treatment with human umbilical cord mesenchymal stem cells and exosomes were further identified by high-throughput microRNA sequencing and protein spectrum sequencing. Our findings suggest that human umbilical cord mesenchymal stem cells and exosomes are a potential treatment for Parkinson’s disease, and that their neuroprotective effects may be mediated by inhibition of excessive microglial proliferation.
基金This study was supported by grants from State Key Laboratory of Medical Neurobiology, Fudan University, and the programs from the Ministry of Science and Technology of China （No. 2010CB945600 and No. 2011CB965100）, the National Natural Science Foundation of China （No. 81070987, No. 30971531）, Shanghai Science Foundation （No. 11PJ1407800）, and National Education Ministry （IRT1168）, International Science ＆ Technology Collaboration Program （No. 2011DF30010）.
文摘Background Our previous studies have indicated that the beneficial effects of grafting neural stem cells （NSCs） overexpressing glial cell line-derived neurotrophic factor （GDNF） in rats after stroke. However, the underlying mechanisms are highly debatable. In this study, we investigated whether neurogenesis, Akt, and extracellular signal- regulated kinase 1/2 （Erkl/2） signaling were involved in this process. Methods Transient ischemic stroke were induced by occluding middle cerebral artery for 2 hours and reperfusion. At 3 days after reperfusion, GDNF/NSCs, NSCs, and vehicle were administered. Immunohistochemical staining was used to evaluate neurogenesis by nestin antibody; phosphorylation of Akt and Erkl/2 was investigated by Western blotting analysis. Results Transplantation of GDNF/NSCs and NSCs significantly increased nestin-positive cells compared to control group （vehicle） from 1 to 7 weeks after reperfusion, and GDNF/NSCs showed stronger effect than NSCs at 2 and 3 weeks after reperfusion. Meanwhile, enhanced phosphorylation level of Erkl/2 was observed in the GDNF/NSCs and NSCs groups compared with control group, and phosphorylation level of Erkl/2 in GDNF/NSCs group was remarkably higher than that of NSCs group at any given time. In contrast, expression of mitogen-activated protein kinase phosphatase-1 （MKP-1）, known as inhibitor of Erkl/2 signaling, was significantly decreased in the GDNF/NSCs and NSCs groups compared with the control group. Moreover, much enhanced and prolonged phosphorylation level of Akt of GDNF/NSCs group was detected compared with control and NSCs group. Conclusion Grafting GDNF/NSCs enhances neurogenesis and activates Akt and Erkl/2 signaling, that may provide the potential for GDNF/NSCs in stroke treatment.
基金financially supported by the Key Laboratory of Metallurgical Emission Reduction&Resources Recycling(Anhui University of Technology),Ministry of Education(No.JKF21-08)the Open Project of Engineering Research Center of Biofilm Water Purification and Utilization Technology of Ministry of Education(No.BWPU2021KF05)+3 种基金the National Natural Science Foundation of China(No.62104003)the Natural Science Foundation of Anhui Province(No.1908085QB75)Anhui Provincial Scientific and Technological Major Project(No.18030801109)the Opening Project of Engineering Technology Research Center of Anhui Education Department for Energy Saving and Pollutant Control in metallurgical process(No.GKF20-7)。
文摘Designing a heterojunction photocatalyst to improve the separation efficiency of photogenerated electrons and holes is of great significance to improve the hydrogen production efficiency.In this work,we report a rational design to grow ZnIN_(2)S_(4)on Mo-MOF-derived N-doped C-coated MoO_(2)(MOZIS),and it has excellent photocatalytic hydrogen production with triethanolamine(TEOA)as sacrificial agent.N-doped C improves the electron transport efficiency between MoO_(2)and ZnIN_(2)S_(4)·The systematic study shows that MOZIS has good properties to promote the effective separation and transfer of photocatalytic charges,which is attributed to the tight contact interface and good energy band structure between MoO_(2)and ZnlN_(2)S_(4).The optimized nanocomposites have a high hydrogen production efficiency of 10.89 mmol·g^(-1)(4 h)under visible light.MOF-derived N-doped C-coated MoO_(2)is an effective strategy to improve the photocatalytic hydrogen production efficiency of ZnIN_(2)S_(4).
基金supported by the National Natural Science Foundation of China,Nos.81371213,81070987,30971531grants from the Ministry of Science and Technology of China,Nos.2010CB945600,2010CB945601(all to QLY)。
文摘Transplantation of neural stem cells(NSCs) can protect neurons in animal stroke models;however, their low rates of survival and neuronal differentiation limit their clinical application. Glial niches, an important location of neural stem cells, regulate survival, proliferation and differentiation of neural stem cells. However, the effects of activated glial cells on neural stem cells remain unclear. In the present study, we explored the effects of activated astrocytes and microglia on neural stem cells in vitro stroke models. We also investigated the effects of combined transplantation of neural stem cells and glial cells after stroke in rats. In a Transwell co-culture system, primary cultured astrocytes, microglia or mixed glial cells were exposed to glutamate or H_2O_2 and then seeded in the upper inserts, while primary neural stem cells were seeded in the lower uncoated wells and cultured for 7 days. Our results showed that microglia were conducive to neurosphere formation and had no effects on apoptosis within neurospheres, while astrocytes and mixed glial cells were conducive to neurosphere differentiation and reduced apoptosis within neurospheres, regardless of their pretreatment. In contrast, microglia and astrocytes induced neuronal differentiation of neural stem cells in differentiation medium, regardless of their pretreatment, with an exception of astrocytes pretreated with H_2O_2. Rat models of ischemic stroke were established by occlusion of the middle cerebral artery. Three days later, 5 × 10~5 neural stem cells with microglia or astrocytes were injected into the right lateral ventricle. Neural stem cell/astrocyte-treated rats displayed better improvement of neurological deficits than neural stem cell only-treated rats at 4 days after cell transplantation. Moreover, neural stem cell/microglia-, and neural stem cell/astrocyte-treated rats showed a significant decrease in ischemic volume compared with neural stem celltreated rats. These findings indicate that microglia and astrocytes exert different e
基金financially supported by the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(No.FRF-IDRY-20-013)the National Natural Science Foundation of China(Nos.51774022,52074020,and 51604017)+2 种基金the State Key Research Development Program of China(Nos.2016YFC0600801 and 2017YFC0804103)the Youth Fund Project of Education Department of Hebei Province,China(No.QN2018202)。
文摘To investigate the impact of an opening and joints with different inclination angles on the mechanical response behavior,the energy evolution characteristics,and distribution law of granite specimens,uniaxial loading tests were performed on the parallel jointed rock samples with an opening.Results indicated an initial decreasing trend of the strength and deformation parameters,which later increases with increased inclination angle,reaching minimum values when the inclination angle is 45°.Evolution curves of the elastic strain energy and dissipated energy with strain of the samples showed step-like gradual mutation characteristics.The peak total energy,peak elastic strain energy,peak dissipated energy,and total input energy during the failure of the samples showed significant nonlinear characteristics with increasing inclination angle.The opening and joints as well as the change of the inclination angle had significant influences on the proportion of the elastic strain energy of the samples prior to the peak,resulting in the difference of the distribution law of input energy.Moreover,the energy mechanism of the sample failure was discussed.Results showed that the energy release was the internal cause of the sudden destruction of the entire rock mass.
基金financially supported by the State Key Research Development Program of China (Nos. 2016YFC0600801, 2017YFC0804103, and 2016YFC0600703)the National Key Basic Research Program of China (973 Program) (No. 2015CB060200)
文摘In this study, we obtained information from twenty-one measurement points on the stress magnitudes and orientations of a gold mine in the Ludong area. We used the overcoring technique with an improved hollow inclusion strain gauge and then analyzed the distribution characteristics of the in situ stress field. The results indicate that the stress field is characterized by σH > σh > σv and σH > σv > σh(where σH, σh, and σv are the maximum horizontal, minimum horizontal, and vertical principal stresses, respectively). The regional stress field is dominated by horizontal principal stress. The σH, σh, and σv values show a gradual increasing trend with depth. The σH is predominantly oriented in the NWW–SEE or near-EW direction. We also confirmed the correspondence between the measured stress field and the regional geological structure. In addition, based on the measured stress data, we discuss the implications of the in situ stress with respect to fault activity in the mine area.
基金financially supported by the Natural Science Foundation of Shandong Province (No. ZR2009CZ004)
文摘Two new sesquiterpenoids,attributable to eudesmane-type（1 and 2,named solajiangxins F and G）,were isolated from the whole plant of Solanum lyratum.Their structures were elucidated on the basis of integrated spectroscopic techniques.In vitro,compounds 1 and 2 were found to show signifcant cytotoxic activity against selected cancer cells,including P-388,HONE-1 and HT-29.
基金supported by the National Natural Science Foundation of China (No.10402033)
文摘The localization damage and deformation characteristics of multiple rock in mined-out area under thick soil layer were investigated by acoustic emission （AE）-based physical similar simulation experiment and damage test combined with the AE theory on rock damage. During different mining courses, the degree of wall rock suffered from mining disturbed process in mined-out area was different, so did the AE density of initial damage and fracture. Some characteristic parameters, including large events, total events, and energy rate, presented fluctuations with temporal and spatial change and take on a certain extent statistic relation. Subsequently, the percent of damage degree was defined and divided into 4 stages, and the localization damage and deformation characteristics of surrounding rock in mined-out area and coal pillars were analyzed quantitatively.
基金Project (No. 30530730) supported by the National Natural ScienceFoundation of China
文摘Excessive dexamethasone (Dex) administrated into pregnant mice during critical periods of palatal development can produce a high incidence of cleft palate. Its mechanisms remain unknown. Vitamin B12 has been shown to antagonize the tera- togenic effects of Dex, which, however, remains controversial. In this study, we investigated the effects of Dex and vitamin B12 on murine embryonic palatal shelf fusion using organ culture of murine embryonic shelves. The explanted palatal shelves on em- bryonic day 14 (E14) were cultured for 24, 48, 72 or 96 h in different concentrations of Dex and/or vitamin B12. The palatal shelves were examined histologically for the morphological alterations on the medial edge epithelium (MEE) and fusion rates among different groups. It was found that the palatal shelves were not fused at 72 h or less of culture in Dex group, while they were completely fused in the control and vitamin B12-treated groups at 72 and 96 h, respectively. The MEE still existed and proliferated. In Dex+vitamin B12 group the palatal shelves were fused at each time point in a similar rate to controls. These results may suggest that Dex causes teratogenesis of murine embryonic palatal shelves and vitamin B12 prevents the teratogenic effect of Dex on palatogenesis on murine embryos in vitro.
基金supported by the National Natural Science Foundation of China (Grant No. 59705011)
文摘The hydrodynamics of batoid swimming motions is investigated using the three-dimensional simulation of a self-propelled body in still water. The kinematics of batoid swimming is characterized by large amplitude undulations of the pectoral fins while the middle part of the body remains straight. The majority of the thrust is generated by pectoral fins. Linear and quadratic amplitude variations are used for the pectoral fins in analyzing the locomotion of the batoid. Navier-Stokes equations are used to solve the unsteady fluid flow. A user defined function and a dynamic mesh method are applied to track the batoid locomotion. The mean swimming velocities of 1.6 BL/s and 1.3 BL/s are achieved, respectively, with thrust coefficients of 0.13 in and 0.095 in the dynamical simulation, where BL/s is the body length per second. The maximum propulsive efficiency 19% is achieved when the frequency of the undulation is 2.2 Hz in both amplitude variations.
基金financially supported by the National Natural Science Foundation of China (Nos.62104003,21972065 and 21803002)the Natural Science Foundation of Anhui Province (No.1908085QB75)+3 种基金Anhui Provincial Natural Science Foundation for Distinguished Young Scholars (No.2008085J11)the Natural Science Foundation of Jiangsu Province (No.BK20220006)the Key projects of Anhui Provincial Department of Education,China (Nos.KJ2021ZD0044 and KJ2020A0228)Hefei National Laboratory for Physical Sciences at the Microscale (No.KF2020006)。
文摘Metal organic framework(MOF) shows great potential in the research field of photocatalysis,and it is a big challenge to achieve efficient photocatalytic activity.In this work,we have successfully grown two-dimensional MOF(2D-MOF) nanosheets on 2D-MOF nanosheets for the first time using a homometallic nodal strategy,and successfully prepared ultrathin nanosheets with tightly bound 2D/2D heterojunctions.2D Ni-BDC nanosheets were used as carriers to grow 2D Ni-TCPP nanosheets on top of them.Ni-TCPP has a high light absorption capacity,thus extending the light absorption range of 2D/2D heterojunctions.The tight coupling of the heterojunction effectively shortens the electron transfer distance,promotes the separation of interracial charges,and improves the photocatalytic activity.Particularly,Ni-BDC/Ni-TCPP-3can achieve to a hydrogen production rate of428.0 μmol·g^(-1),approximately 5.75 times higher than NiBDC and 5.24 times higher than Ni-TCPP,respectively.Thus,2D-MOF/2D-MOF heterojunctions provide a promising strategy for enhancing photocatalytic performance through rational heterostructure design with homometallic node strategy.
