Objective Cerebrospinal fluid(CSF)plays a crucial role in maintaining the homeostasis of the central nervous system(CNS).CSF rapidly exchanges with interstitial fluid(ISF)via the glymphatic system within the brain par...Objective Cerebrospinal fluid(CSF)plays a crucial role in maintaining the homeostasis of the central nervous system(CNS).CSF rapidly exchanges with interstitial fluid(ISF)via the glymphatic system within the brain parenchyma.CSF-ISF circulation and its associated mechanisms are often referred to as the brain lymphatic system.This system is connected directly to meningeal lymphatic vessels(mLVs),jointly performing the function of clearing metabolic waste from the CNS.Emerging evidence indicates that this system is closely associated with the onset and progression of neurodegenerative diseases(NDs)such as Alzheimer’s disease(AD).Importantly,abnormal CSF circulation is not only a downstream consequence of AD pathology,but also a risk factor.In AD,the dynamics of CSF flow within the CNS are diminished,immune dysregulation occurs,and this may increase the risk of AD by exacerbating the burden of amyloidβ-protein(Aβ).In the mouse model of AD,impaired CSF flow compromises this clearance function,leading to cognitive deficits.Clinically,acupuncture at cognition-related acupoints is commonly used for the prevention and treatment of AD.However,whether its therapeutic effects are mediated through the modulation of CSF dynamics remains unclear.This study aimed to evaluate the impact of acupuncture on CSF flow and investigate its acupoint specificity.Methods Mice were randomly assigned to experimental groups for the different electroacupuncture groups with the following acupoints:Baihui point(GV 20),Ear point,Neiguan point(PC 6),and Tianshu point(ST 25).Wild-type mice on a C57BL/6J background were used as controls.Fluorescent tracer was injected into the cisterna magna to label CSF flow.Fluorescence imaging was employed to assess the distribution of CSF within the brain before and after acupuncture stimulation.Results Following tracer injection into the cisterna magna,fluorescence signals rapidly reached the cerebellum and medulla—the regions closest to the injection site.Fluorescence intensity was higher in ventral brain regions compared to dorsal regions,likely due to greater vascular density in ventral areas facilitating CSF-ISF exchange.Electroacupuncture at the GV 20 produced the most pronounced enhancement of CSF across the whole brain,while stimulation at the ST 25 primarily augmented flow within subcortical regions.In contrast,electroacupuncture at the Ear point or the PC 6 had no observable effect on CSF in mice.Conclusion Electroacupuncture promotes CSF flow into the brain parenchyma in an acupoint-specific manner,with GV 20 exhibiting the most pronounced enhancement of CSF dynamics.These findings suggest that acupuncture-mediated facilitation of CSF flow may represent a potential therapeutic strategy for preventing or delaying age-related cognitive decline.展开更多
Extensive experiments suggest that kurtosis-based fingerprint features are effective for specific emitter identification (SEI). Nevertheless, the lack of mechanistic explanation restricts the use of fingerprint featur...Extensive experiments suggest that kurtosis-based fingerprint features are effective for specific emitter identification (SEI). Nevertheless, the lack of mechanistic explanation restricts the use of fingerprint features to a data-driven technique and fur-ther reduces the adaptability of the technique to other datasets. To address this issue, the mechanism how the phase noise of high-frequency oscillators and the nonlinearity of power ampli-fiers affect the kurtosis of communication signals is investigated. Mathematical models are derived for intentional modulation (IM) and unintentional modulation (UIM). Analysis indicates that the phase noise of high-frequency oscillators and the nonlinearity of power amplifiers affect the kurtosis frequency and amplitude, respectively. A novel SEI method based on frequency and ampli-tude of the signal kurtosis (FA-SK) is further proposed. Simula-tion and real-world experiments validate theoretical analysis and also confirm the efficiency and effectiveness of the proposed method.展开更多
Mo_(2)CT_(x)MXene is a novel two-dimensional material,which is generally made by the etching of inorganic acid solutions,such as hydrofluoric acid(HF)or hydrochloric acid(HCl).Those solutions are always corrosive and ...Mo_(2)CT_(x)MXene is a novel two-dimensional material,which is generally made by the etching of inorganic acid solutions,such as hydrofluoric acid(HF)or hydrochloric acid(HCl).Those solutions are always corrosive and hazardous.In this paper,a mild organic acid,acetic acid(CH_(3)COOH),was selected to synthesize Mo_(2)CT_(x)MXene.30 mL acetic acid(HAc)with the concentration of 13 mol/L was mixed with 2 g acetate(CH_(3)COONa or CH_(3)COOK)and 10 mL water to make etching solution(NaAc+HAc or KAc+HAc).In the solution,the concentration of CH_(3)COO^(-)was 10 mol/L,the concentration of Na^(+)/K^(+)is 0.6/0.5 mol/L.The pH value is 2.8.Mo_(2)CT_(x)was obtained by hydrothermal etching at 240℃for 1 d.Compared with the general method of HF etching,the etchant is milder and the etching process is safer.On the surface of Mo_(2)CT_(x)nanosheet made by this method,acetate group(CH_(3)COO^(-))was adsorbed as termination,which is larger than the F/O/OH termination of that made by general HF etching.The lattice parameter c(LP c)of Mo_(2)CT_(x)etched with NaAc+HAc/KAc+HAc is 21.09Å/20.89Å.Moreover,the specific surface areas of the samples etched by NaAc+HAc and KAc+HAc were 18.1 m^(2)/g and 14.1 m^(2)/g,respectively,which were much larger than those etched by conventional methods.As the anode of lithium-ion battery,the specific capacity under current density of 100 mA/g at 100 th cycle was 108 mA·h/g,which is higher than the capacity of samples made by general HF etching.This work reports a novel method to make Mo_(2)CT_(x)MXene by the solution of mild acetic acid.The samples made by this method had very high specific surface area and relatively high lithium-storage performance.展开更多
A three-dimensional transient numerical simulation was conducted to study the pressure fluctuations in low-specific-speed centrifugal pumps. The characteristics of the inner flow were investigated using the SST k-ω t...A three-dimensional transient numerical simulation was conducted to study the pressure fluctuations in low-specific-speed centrifugal pumps. The characteristics of the inner flow were investigated using the SST k-ω turbulence model. The distributions of pressure fluctuations in the impeller and the volute were recorded, and the pressure fluctuation intensity was analyzed comprehensively, at the design condition, using statistical methods. The results show that the pressure fluctuation intensity increases along the impeller streamline from the leading edge to the trailing edge. In the impeller passage, the intensity near the shroud is much higher than that near the hub at thc inlet. However, the intensity at the middle passage is almost equal to the intensity at the outlet. The pressure fluctuation intensity is the highest at the trailing edge on the pressure side and near the tongue because of the rotor-stator interaction. The distribution of pressure fluctuation intensity is symmetrical in the axial cross sections of the volute channel. However, this intensity decreases with increasing radial distance. Hence, the pressure fluctuation intensity can be reduced by modifying the geometry of the leading edge in the impeller and the tongue in the volute.展开更多
A series of batch experiments were conducted in 125 mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upflo...A series of batch experiments were conducted in 125 mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upflow anaerobic sludge bed（UASB） and expanded granular sludge bed（EGSB） reactors. The effects of pH value and temperature on toxicity of ammonia nitrogen to anaerobes were investigated. The results show that the specific methanogenic activity of anaerobic granular sludge suffers inhibition from ammonia nitrogen, the concentrations of ammonia nitrogen that produce 50 % inhibition of specific methanogenic activity for sludge from UASB and EGSB reactor are 2.35 and 2.75 g/L, respectively. Hydrogen utilizing methanogens suffers less inhibition from ammonia mtrogen than that of acetate utilizing methanogens. Hydrogen-producing acetogens that utilize propionate and butyrate as substrates suffer serious inhibition from ammonia nitrogen. The toxicity of ammonia nitrogen to anaerobic granular sludge enhances when pH value and temperature increase. Anaerobic granular sludge can bear higher concentrations of ammonia nitrogen after being acclimated by ammonia nitrogen for 7 d.展开更多
Connected a segment of CMV enhancer to the front of MyoG gene promoter and then constructed the corresponding dual luciferase expression vector pGL3-CMV-MyoGpro. We set four eukaryotic expression vectors including pGL...Connected a segment of CMV enhancer to the front of MyoG gene promoter and then constructed the corresponding dual luciferase expression vector pGL3-CMV-MyoGpro. We set four eukaryotic expression vectors including pGL3-CMV, pGL3MyoGpro, pGL3-CMV-MyoGpro, and pGL3-Basic which contained CMV promoter, MyoG promoter, CMV-MyoG synthesis promoter, and a promoterless negative control, respectively. Then the four vectors and internal control Renilla luciferase report gene vector phRL-TK were transfected into bovine skeletal muscle satellite cells, mouse C2C12 cells and bovine fetal fibroblast cells to detect the promoter activity with dual luciferase report system. The results showed that CMV enhancer could significantly improve the transcription activity of bovine MyoG gene promoter in muscle satellite cells and mouse C2C12 cells, and it had certain specificity. This study provided experimental materials for increasing the high expression of exogenous gene in bovine muscle cells, and also laid the molecular theoretical basis for obtaining the high specific promoter of bovine muscle and the transgenic beef cattle.展开更多
Cotton disea ses represent a major challenge to cotton growth.Cloning of a cotton pathogen re-sponse gene and promoter is of great importance to improve disease resistance.In this study,a full length CC-NBS-LRRgene(GH...Cotton disea ses represent a major challenge to cotton growth.Cloning of a cotton pathogen re-sponse gene and promoter is of great importance to improve disease resistance.In this study,a full length CC-NBS-LRRgene(GHNBS)and its 5L flanking sequence have been cloned by race and tail PCR and further studied.The entire coding region is 2583 bp and enco des a polypeptide of 861 a mino acids with 28%maximum homology to an R gene of Arabi dopsis depo sited in the GenBank.Semi quantitativeRT-PCR showed thatGHNBS was expressed in floral buds,petals,phloem,root s,and leaves,and it has a greater exp ression pattern in roots and leaves.展开更多
This work aims at selecting optimal operating variables to obtain the minimum specific energy(SE) in sawing of rocks.A particular granite was sampled and sawn by a fully automated circular diamond sawblades.The periph...This work aims at selecting optimal operating variables to obtain the minimum specific energy(SE) in sawing of rocks.A particular granite was sampled and sawn by a fully automated circular diamond sawblades.The peripheral speed,the traverse speed,the cut depth and the flow rate of cooling fluid were selected as the operating variables.Taguchi approach was adopted as a statistical design of experimental technique for optimization studies.The results were evaluated based on the analysis of variance and signal-to-noise ratio(S/N ratio).Statistically significant operating variables and their percentage contribution to the process were also determined.Additionally,a statistical model was developed to demonstrate the relationship between SE and operating variables using regression analysis and the model was then verified.It was found that the optimal combination of operating variables for minimum SE is the peripheral speed of 25 m/s,the traverse speed of 70 cm/min,the cut depth of 2 cm and the flow rate of cooling fluid of 100 mL/s.The cut depth and traverse speed were statistically determined as the significant operating variables affecting the SE,respectively.Furthermore,the regression model results reveal that the predictive model has a high applicability for practical applications.展开更多
Existing specific emitter identification(SEI)methods based on hand-crafted features have drawbacks of losing feature information and involving multiple processing stages,which reduce the identification accuracy of emi...Existing specific emitter identification(SEI)methods based on hand-crafted features have drawbacks of losing feature information and involving multiple processing stages,which reduce the identification accuracy of emitters and complicate the procedures of identification.In this paper,we propose a deep SEI approach via multidimensional feature extraction for radio frequency fingerprints(RFFs),namely,RFFsNet-SEI.Particularly,we extract multidimensional physical RFFs from the received signal by virtue of variational mode decomposition(VMD)and Hilbert transform(HT).The physical RFFs and I-Q data are formed into the balanced-RFFs,which are then used to train RFFsNet-SEI.As introducing model-aided RFFs into neural network,the hybrid-driven scheme including physical features and I-Q data is constructed.It improves physical interpretability of RFFsNet-SEI.Meanwhile,since RFFsNet-SEI identifies individual of emitters from received raw data in end-to-end,it accelerates SEI implementation and simplifies procedures of identification.Moreover,as the temporal features and spectral features of the received signal are both extracted by RFFsNet-SEI,identification accuracy is improved.Finally,we compare RFFsNet-SEI with the counterparts in terms of identification accuracy,computational complexity,and prediction speed.Experimental results illustrate that the proposed method outperforms the counterparts on the basis of simulation dataset and real dataset collected in the anechoic chamber.展开更多
In order to overcome the nonlinearity of Mises criterion, a new linear yield criterion with a dodecagon shape of the same perimeter as Mises criterion was derived by means of geometrical analysis. Its specific plastic...In order to overcome the nonlinearity of Mises criterion, a new linear yield criterion with a dodecagon shape of the same perimeter as Mises criterion was derived by means of geometrical analysis. Its specific plastic work rate expressed as a linear function of the yield stress, the maximum and minimum strains was also deduced and compared with that of Mises criterion. The physical meaning of the proposed yield criterion is that yielding of materials begins when the shear yield stress τs reaches the magnitude of 0.594σs. By introducing the Lode parameter, validation of evolution expressions of the proposed yield criterion with those based on Tresca, Mises and TSS criteria as well as available classical yield experimental results of various metals shows that the present results intersect with Mises results and coincide well with experimental data. Moreover, further application to the limit analysis of circle plate as an example is performed to demonstrate the effectiveness of the proposed yield criterion, and the subsequent comparison of limit loads with the Tresca analytical solutions and Mises numerical results shows that the present results are higher than the Tresca analytical results, and are in good agreement with the Mises numerical results.展开更多
Endothelial lipase(EL)has been implicated in high-density lipoprotein(HDL)metabolism and the pathogenetic progress of atherosclerosis,so its specific inhibitors are expected to be useful for the treatment of cardiovas...Endothelial lipase(EL)has been implicated in high-density lipoprotein(HDL)metabolism and the pathogenetic progress of atherosclerosis,so its specific inhibitors are expected to be useful for the treatment of cardiovascular disease.In addition to the high homology of EL with other lipases such as lipoprotein lipase(LPL),the scoring bias of current docking programs toward large molecules and large protein-binding pockets also makes it difficult to find specific EL inhibitors by docking-based virtual screening.Herein,we conducted docking-based virtual screening of the Specs database for EL and LPL firstly,and we found the scoring bias phenomenon.From the docking results of the Specs database,we established standard curves for the binding energies of EL and LPL based on heavy atom number and contact area to correct the dock energy score statistically.We then validated the correctional effects of these curves in the screening of a validation set.Furthermore,the traditional Chinese medicine database(TCMD)was screened by docking using the score correction strategy.The dock ranks before and after correction were compared to confirm the screening effectiveness.Moreover,some compounds exhibiting better affinity for EL than LPL after correction as well as some compounds with antihyperlipidemic activity that may be specific EL inhibitors were analyzed to study their interaction mechanisms.The developed score correction strategy should be helpful to improve the hit rate in docking-based virtual screening.The molecules we identified should be useful for experimental scientists to prioritize drug candidates and provide groundwork for potential therapies of hyperlipidemia and atherosclerosis.展开更多
This paper is concerned with the control synthesis problem via dynamic output feedback for linear continuous-time systems with mixed frequency small gain specifications.A new method for designing dynamic output feedba...This paper is concerned with the control synthesis problem via dynamic output feedback for linear continuous-time systems with mixed frequency small gain specifications.A new method for designing dynamic output feedback controllers is presented such that the resulting closed-loop systems are asymptotically stable and meet the requirements of small gain specifications in both finite frequency ranges and the entire frequency range.The design conditions are given in terms of solutions to a set of linear matrix inequalities(LMIs).Finally,a numerical example is given to illustrate the design procedure and the advantage of the proposed method in comparison with the existing one.展开更多
It is shown that it is not correct to estimate energetic characteristics of different compounds of solid composite propellants by evaluation of the specific impulse values of these components serving as an only compon...It is shown that it is not correct to estimate energetic characteristics of different compounds of solid composite propellants by evaluation of the specific impulse values of these components serving as an only component in the formulation.Such an approach may turn the researcher to a wrong conclusion.One has to compare compound′s potential in formulations close to real,e.g.at least with necessary amount of binders.Dependences of specific impulse upon element content of highenthalpy CHNO oxidizer,its enthalpy of formation,and kind of binder have been found.展开更多
A series of steady and unsteady numerical calculations of the internal flow in mixed-flow pumps with three different specific speeds were carried out based on the N-S equation coupled with the standard k-εturbulence ...A series of steady and unsteady numerical calculations of the internal flow in mixed-flow pumps with three different specific speeds were carried out based on the N-S equation coupled with the standard k-εturbulence model under different operating conditions to investigate the relationship between the impeller specific speed and the pump performance as well as pressure pulsations.Meanwhile,the pump performance and pressure pulsations inside the mixed-flow pump with three different specific speeds were also analyzed and compared with the corresponding test data.From the results,the averaged deviations between the predicted and tested head among different impellers are below 5%,and with respect to the equivalent impeller specific speeds of 280 and 260,the values are 4.30%and 3.69%,respectively.For all the impeller schemes,the best efficiency point of the mixed-flow pump is found at the flow rate of 1.2 Q_(d) and the higher head deviation occurs at lower flow rates.Especially,it can be found that the specific speed has a slight effect on the pressure fluctuation in the impellers.Eventually,it is determined that the pump performance curves calculated by numerical simu-lations have good agreement with the relevant experimental results,which verifies that the numerical methods used in the present study are accurate to a certain extent.Furthermore,the results also provide some references to the pressure pulsation analysis and the performance improvement of the mixed-flow pump design.展开更多
文摘Objective Cerebrospinal fluid(CSF)plays a crucial role in maintaining the homeostasis of the central nervous system(CNS).CSF rapidly exchanges with interstitial fluid(ISF)via the glymphatic system within the brain parenchyma.CSF-ISF circulation and its associated mechanisms are often referred to as the brain lymphatic system.This system is connected directly to meningeal lymphatic vessels(mLVs),jointly performing the function of clearing metabolic waste from the CNS.Emerging evidence indicates that this system is closely associated with the onset and progression of neurodegenerative diseases(NDs)such as Alzheimer’s disease(AD).Importantly,abnormal CSF circulation is not only a downstream consequence of AD pathology,but also a risk factor.In AD,the dynamics of CSF flow within the CNS are diminished,immune dysregulation occurs,and this may increase the risk of AD by exacerbating the burden of amyloidβ-protein(Aβ).In the mouse model of AD,impaired CSF flow compromises this clearance function,leading to cognitive deficits.Clinically,acupuncture at cognition-related acupoints is commonly used for the prevention and treatment of AD.However,whether its therapeutic effects are mediated through the modulation of CSF dynamics remains unclear.This study aimed to evaluate the impact of acupuncture on CSF flow and investigate its acupoint specificity.Methods Mice were randomly assigned to experimental groups for the different electroacupuncture groups with the following acupoints:Baihui point(GV 20),Ear point,Neiguan point(PC 6),and Tianshu point(ST 25).Wild-type mice on a C57BL/6J background were used as controls.Fluorescent tracer was injected into the cisterna magna to label CSF flow.Fluorescence imaging was employed to assess the distribution of CSF within the brain before and after acupuncture stimulation.Results Following tracer injection into the cisterna magna,fluorescence signals rapidly reached the cerebellum and medulla—the regions closest to the injection site.Fluorescence intensity was higher in ventral brain regions compared to dorsal regions,likely due to greater vascular density in ventral areas facilitating CSF-ISF exchange.Electroacupuncture at the GV 20 produced the most pronounced enhancement of CSF across the whole brain,while stimulation at the ST 25 primarily augmented flow within subcortical regions.In contrast,electroacupuncture at the Ear point or the PC 6 had no observable effect on CSF in mice.Conclusion Electroacupuncture promotes CSF flow into the brain parenchyma in an acupoint-specific manner,with GV 20 exhibiting the most pronounced enhancement of CSF dynamics.These findings suggest that acupuncture-mediated facilitation of CSF flow may represent a potential therapeutic strategy for preventing or delaying age-related cognitive decline.
基金supported by the Youth Science and Technology Innovation Award of National University of Defense Technology (18/19-QNCXJ)the National Science Foundation of China (62271494)
文摘Extensive experiments suggest that kurtosis-based fingerprint features are effective for specific emitter identification (SEI). Nevertheless, the lack of mechanistic explanation restricts the use of fingerprint features to a data-driven technique and fur-ther reduces the adaptability of the technique to other datasets. To address this issue, the mechanism how the phase noise of high-frequency oscillators and the nonlinearity of power ampli-fiers affect the kurtosis of communication signals is investigated. Mathematical models are derived for intentional modulation (IM) and unintentional modulation (UIM). Analysis indicates that the phase noise of high-frequency oscillators and the nonlinearity of power amplifiers affect the kurtosis frequency and amplitude, respectively. A novel SEI method based on frequency and ampli-tude of the signal kurtosis (FA-SK) is further proposed. Simula-tion and real-world experiments validate theoretical analysis and also confirm the efficiency and effectiveness of the proposed method.
基金Projects(52372284,52275187,62004143)supported by the National Natural Science Foundation of ChinaProject(2022BAA084)supported by the Key R&D Program of Hubei Province,ChinaProject(232300421135)supported by the Natural Science Foundation of Henan Province,China。
文摘Mo_(2)CT_(x)MXene is a novel two-dimensional material,which is generally made by the etching of inorganic acid solutions,such as hydrofluoric acid(HF)or hydrochloric acid(HCl).Those solutions are always corrosive and hazardous.In this paper,a mild organic acid,acetic acid(CH_(3)COOH),was selected to synthesize Mo_(2)CT_(x)MXene.30 mL acetic acid(HAc)with the concentration of 13 mol/L was mixed with 2 g acetate(CH_(3)COONa or CH_(3)COOK)and 10 mL water to make etching solution(NaAc+HAc or KAc+HAc).In the solution,the concentration of CH_(3)COO^(-)was 10 mol/L,the concentration of Na^(+)/K^(+)is 0.6/0.5 mol/L.The pH value is 2.8.Mo_(2)CT_(x)was obtained by hydrothermal etching at 240℃for 1 d.Compared with the general method of HF etching,the etchant is milder and the etching process is safer.On the surface of Mo_(2)CT_(x)nanosheet made by this method,acetate group(CH_(3)COO^(-))was adsorbed as termination,which is larger than the F/O/OH termination of that made by general HF etching.The lattice parameter c(LP c)of Mo_(2)CT_(x)etched with NaAc+HAc/KAc+HAc is 21.09Å/20.89Å.Moreover,the specific surface areas of the samples etched by NaAc+HAc and KAc+HAc were 18.1 m^(2)/g and 14.1 m^(2)/g,respectively,which were much larger than those etched by conventional methods.As the anode of lithium-ion battery,the specific capacity under current density of 100 mA/g at 100 th cycle was 108 mA·h/g,which is higher than the capacity of samples made by general HF etching.This work reports a novel method to make Mo_(2)CT_(x)MXene by the solution of mild acetic acid.The samples made by this method had very high specific surface area and relatively high lithium-storage performance.
基金Projects(51239005,51009072) supported by the National Natural Science Foundation of ChinaProject(2011BAF14B04) supported by the National Science&Technology Pillar Program of ChinaProject(13JDG084) supported by the Research Foundation for Advanced Talents of Jiansu University,China
文摘A three-dimensional transient numerical simulation was conducted to study the pressure fluctuations in low-specific-speed centrifugal pumps. The characteristics of the inner flow were investigated using the SST k-ω turbulence model. The distributions of pressure fluctuations in the impeller and the volute were recorded, and the pressure fluctuation intensity was analyzed comprehensively, at the design condition, using statistical methods. The results show that the pressure fluctuation intensity increases along the impeller streamline from the leading edge to the trailing edge. In the impeller passage, the intensity near the shroud is much higher than that near the hub at thc inlet. However, the intensity at the middle passage is almost equal to the intensity at the outlet. The pressure fluctuation intensity is the highest at the trailing edge on the pressure side and near the tongue because of the rotor-stator interaction. The distribution of pressure fluctuation intensity is symmetrical in the axial cross sections of the volute channel. However, this intensity decreases with increasing radial distance. Hence, the pressure fluctuation intensity can be reduced by modifying the geometry of the leading edge in the impeller and the tongue in the volute.
文摘A series of batch experiments were conducted in 125 mL serum bottles to assess the toxicity of different concentrations of ammonia nitrogen to the specific methanogenic activity of anaerobic granular sludge from upflow anaerobic sludge bed（UASB） and expanded granular sludge bed（EGSB） reactors. The effects of pH value and temperature on toxicity of ammonia nitrogen to anaerobes were investigated. The results show that the specific methanogenic activity of anaerobic granular sludge suffers inhibition from ammonia nitrogen, the concentrations of ammonia nitrogen that produce 50 % inhibition of specific methanogenic activity for sludge from UASB and EGSB reactor are 2.35 and 2.75 g/L, respectively. Hydrogen utilizing methanogens suffers less inhibition from ammonia mtrogen than that of acetate utilizing methanogens. Hydrogen-producing acetogens that utilize propionate and butyrate as substrates suffer serious inhibition from ammonia nitrogen. The toxicity of ammonia nitrogen to anaerobic granular sludge enhances when pH value and temperature increase. Anaerobic granular sludge can bear higher concentrations of ammonia nitrogen after being acclimated by ammonia nitrogen for 7 d.
基金Supported by the Major Special Projects of New Product Training of Transgenic Organisms(zx080072008-2008)
文摘Connected a segment of CMV enhancer to the front of MyoG gene promoter and then constructed the corresponding dual luciferase expression vector pGL3-CMV-MyoGpro. We set four eukaryotic expression vectors including pGL3-CMV, pGL3MyoGpro, pGL3-CMV-MyoGpro, and pGL3-Basic which contained CMV promoter, MyoG promoter, CMV-MyoG synthesis promoter, and a promoterless negative control, respectively. Then the four vectors and internal control Renilla luciferase report gene vector phRL-TK were transfected into bovine skeletal muscle satellite cells, mouse C2C12 cells and bovine fetal fibroblast cells to detect the promoter activity with dual luciferase report system. The results showed that CMV enhancer could significantly improve the transcription activity of bovine MyoG gene promoter in muscle satellite cells and mouse C2C12 cells, and it had certain specificity. This study provided experimental materials for increasing the high expression of exogenous gene in bovine muscle cells, and also laid the molecular theoretical basis for obtaining the high specific promoter of bovine muscle and the transgenic beef cattle.
文摘Cotton disea ses represent a major challenge to cotton growth.Cloning of a cotton pathogen re-sponse gene and promoter is of great importance to improve disease resistance.In this study,a full length CC-NBS-LRRgene(GHNBS)and its 5L flanking sequence have been cloned by race and tail PCR and further studied.The entire coding region is 2583 bp and enco des a polypeptide of 861 a mino acids with 28%maximum homology to an R gene of Arabi dopsis depo sited in the GenBank.Semi quantitativeRT-PCR showed thatGHNBS was expressed in floral buds,petals,phloem,root s,and leaves,and it has a greater exp ression pattern in roots and leaves.
文摘This work aims at selecting optimal operating variables to obtain the minimum specific energy(SE) in sawing of rocks.A particular granite was sampled and sawn by a fully automated circular diamond sawblades.The peripheral speed,the traverse speed,the cut depth and the flow rate of cooling fluid were selected as the operating variables.Taguchi approach was adopted as a statistical design of experimental technique for optimization studies.The results were evaluated based on the analysis of variance and signal-to-noise ratio(S/N ratio).Statistically significant operating variables and their percentage contribution to the process were also determined.Additionally,a statistical model was developed to demonstrate the relationship between SE and operating variables using regression analysis and the model was then verified.It was found that the optimal combination of operating variables for minimum SE is the peripheral speed of 25 m/s,the traverse speed of 70 cm/min,the cut depth of 2 cm and the flow rate of cooling fluid of 100 mL/s.The cut depth and traverse speed were statistically determined as the significant operating variables affecting the SE,respectively.Furthermore,the regression model results reveal that the predictive model has a high applicability for practical applications.
基金supported by the National Natural Science Foundation of China(62061003)Sichuan Science and Technology Program(2021YFG0192)the Research Foundation of the Civil Aviation Flight University of China(ZJ2020-04,J2020-033)。
文摘Existing specific emitter identification(SEI)methods based on hand-crafted features have drawbacks of losing feature information and involving multiple processing stages,which reduce the identification accuracy of emitters and complicate the procedures of identification.In this paper,we propose a deep SEI approach via multidimensional feature extraction for radio frequency fingerprints(RFFs),namely,RFFsNet-SEI.Particularly,we extract multidimensional physical RFFs from the received signal by virtue of variational mode decomposition(VMD)and Hilbert transform(HT).The physical RFFs and I-Q data are formed into the balanced-RFFs,which are then used to train RFFsNet-SEI.As introducing model-aided RFFs into neural network,the hybrid-driven scheme including physical features and I-Q data is constructed.It improves physical interpretability of RFFsNet-SEI.Meanwhile,since RFFsNet-SEI identifies individual of emitters from received raw data in end-to-end,it accelerates SEI implementation and simplifies procedures of identification.Moreover,as the temporal features and spectral features of the received signal are both extracted by RFFsNet-SEI,identification accuracy is improved.Finally,we compare RFFsNet-SEI with the counterparts in terms of identification accuracy,computational complexity,and prediction speed.Experimental results illustrate that the proposed method outperforms the counterparts on the basis of simulation dataset and real dataset collected in the anechoic chamber.
基金Project(51074052)supported by the National Natural Science Foundation of ChinaProject(BK20140334)supported by the Basic Research Program of Jiangsu Province+2 种基金ChinaProject(14KJB460024)supported by the Natural Science Foundation of Jiangsu Higher Education Institutions of ChinaProject(2014M561707)supported by China Postdoctoral Science Foundation
文摘In order to overcome the nonlinearity of Mises criterion, a new linear yield criterion with a dodecagon shape of the same perimeter as Mises criterion was derived by means of geometrical analysis. Its specific plastic work rate expressed as a linear function of the yield stress, the maximum and minimum strains was also deduced and compared with that of Mises criterion. The physical meaning of the proposed yield criterion is that yielding of materials begins when the shear yield stress τs reaches the magnitude of 0.594σs. By introducing the Lode parameter, validation of evolution expressions of the proposed yield criterion with those based on Tresca, Mises and TSS criteria as well as available classical yield experimental results of various metals shows that the present results intersect with Mises results and coincide well with experimental data. Moreover, further application to the limit analysis of circle plate as an example is performed to demonstrate the effectiveness of the proposed yield criterion, and the subsequent comparison of limit loads with the Tresca analytical solutions and Mises numerical results shows that the present results are higher than the Tresca analytical results, and are in good agreement with the Mises numerical results.
基金The project was supported by the National Natural Science Foundation of China(21572010,21272017)
文摘Endothelial lipase(EL)has been implicated in high-density lipoprotein(HDL)metabolism and the pathogenetic progress of atherosclerosis,so its specific inhibitors are expected to be useful for the treatment of cardiovascular disease.In addition to the high homology of EL with other lipases such as lipoprotein lipase(LPL),the scoring bias of current docking programs toward large molecules and large protein-binding pockets also makes it difficult to find specific EL inhibitors by docking-based virtual screening.Herein,we conducted docking-based virtual screening of the Specs database for EL and LPL firstly,and we found the scoring bias phenomenon.From the docking results of the Specs database,we established standard curves for the binding energies of EL and LPL based on heavy atom number and contact area to correct the dock energy score statistically.We then validated the correctional effects of these curves in the screening of a validation set.Furthermore,the traditional Chinese medicine database(TCMD)was screened by docking using the score correction strategy.The dock ranks before and after correction were compared to confirm the screening effectiveness.Moreover,some compounds exhibiting better affinity for EL than LPL after correction as well as some compounds with antihyperlipidemic activity that may be specific EL inhibitors were analyzed to study their interaction mechanisms.The developed score correction strategy should be helpful to improve the hit rate in docking-based virtual screening.The molecules we identified should be useful for experimental scientists to prioritize drug candidates and provide groundwork for potential therapies of hyperlipidemia and atherosclerosis.
基金Supported by Program for New Century Excellent Talents in University(NCET-04-0283)the Funds for Creative Research Groups of China(60521003)+4 种基金Program for Changjiang Scholars and Innovative Research Team in University(IRT0421)the State Key Program of National Natural Science Foundation of China(60534010)and National Natural Science Foundation of China(60674021)the Funds of Ph.D.Program of Ministry of Education,China(20060145019)the 111 Project(B08015)
文摘This paper is concerned with the control synthesis problem via dynamic output feedback for linear continuous-time systems with mixed frequency small gain specifications.A new method for designing dynamic output feedback controllers is presented such that the resulting closed-loop systems are asymptotically stable and meet the requirements of small gain specifications in both finite frequency ranges and the entire frequency range.The design conditions are given in terms of solutions to a set of linear matrix inequalities(LMIs).Finally,a numerical example is given to illustrate the design procedure and the advantage of the proposed method in comparison with the existing one.
文摘It is shown that it is not correct to estimate energetic characteristics of different compounds of solid composite propellants by evaluation of the specific impulse values of these components serving as an only component in the formulation.Such an approach may turn the researcher to a wrong conclusion.One has to compare compound′s potential in formulations close to real,e.g.at least with necessary amount of binders.Dependences of specific impulse upon element content of highenthalpy CHNO oxidizer,its enthalpy of formation,and kind of binder have been found.
基金National Natural Science Foundation of China(51976078)Senior Personnel Scientific Research Foundation of Jiangsu University:(15JDG073)Open Research Subject of Key Laboratory of Fluid and Power Machinery,Ministry of Education(szjj2016-065)。
文摘A series of steady and unsteady numerical calculations of the internal flow in mixed-flow pumps with three different specific speeds were carried out based on the N-S equation coupled with the standard k-εturbulence model under different operating conditions to investigate the relationship between the impeller specific speed and the pump performance as well as pressure pulsations.Meanwhile,the pump performance and pressure pulsations inside the mixed-flow pump with three different specific speeds were also analyzed and compared with the corresponding test data.From the results,the averaged deviations between the predicted and tested head among different impellers are below 5%,and with respect to the equivalent impeller specific speeds of 280 and 260,the values are 4.30%and 3.69%,respectively.For all the impeller schemes,the best efficiency point of the mixed-flow pump is found at the flow rate of 1.2 Q_(d) and the higher head deviation occurs at lower flow rates.Especially,it can be found that the specific speed has a slight effect on the pressure fluctuation in the impellers.Eventually,it is determined that the pump performance curves calculated by numerical simu-lations have good agreement with the relevant experimental results,which verifies that the numerical methods used in the present study are accurate to a certain extent.Furthermore,the results also provide some references to the pressure pulsation analysis and the performance improvement of the mixed-flow pump design.
