[Objective] This study aimed to investigate the feasibility of transgenesis by injecting exogenous DNA into zygote cytoplasm of Buffalo. [Method] Buffalo oocytes were randomly divided into two groups 20-22 h after in ...[Objective] This study aimed to investigate the feasibility of transgenesis by injecting exogenous DNA into zygote cytoplasm of Buffalo. [Method] Buffalo oocytes were randomly divided into two groups 20-22 h after in vitro maturation. One group of oocytes was introduced with about 7.5 pl of 50 μg/ml DNA solution containing linear EGFP fragment by cytoplasmic injection 7-10 h or 18-20 h after in vitro fertilization (IVF); the other group of oocytes was introduced with mixture of a single buffalo sperm and about 7.5 pl of 50 μg/ml DNA solution containing linear EGFP fragment by cytoplasmic injection (generally called ICSI-Mediated Gene Transfer, ICSI-Tr). Expression of exogenous DNA was observed and recorded during the process of embryonic development. [Result] Early embryonic gene expression efficiency and blastocyst gene expression efficiency in IVF injection group showed no significant difference compared with that in ICSI-Tr group (P0.05). In addition, the cleavage rate and early embryonic gene expression efficiency in IVF injection group were significantly higher with injection at 7-10 h post IVF than that at 18-20 h post IVF (P0.05). [Conclusion] These results indicate that transgenic buffalo embryos can be generated by injecting exogenous DNA into cytoplasm of IVF oocytes, and the optimal injection time is 7-10 h post IVF.展开更多
On the basis of detailed analysis of a novel harmonic counteracting method which can be used to effectively compensate the supply line harmonic currents of a passive single phase diode bridge rectifier, this paper pr...On the basis of detailed analysis of a novel harmonic counteracting method which can be used to effectively compensate the supply line harmonic currents of a passive single phase diode bridge rectifier, this paper presents two simpler single phase diode bridge rectifier configurations and their alternatives which can achieve low supply line current THD(total harmonic distortion) too. Moreover, this paper also proposes a few passive hamonic counteracting networks for multi single phase rectifiers which are connected in parallel.展开更多
The poloidal rotation of the magnetized edge plasma in tokamak driven by the ponderomotive force which is generated by injecting lower hybrid wave(LHW) electric field has been studied. The LHW is launched from a waveg...The poloidal rotation of the magnetized edge plasma in tokamak driven by the ponderomotive force which is generated by injecting lower hybrid wave(LHW) electric field has been studied. The LHW is launched from a waveguide in the plasma edge, and by Brambilla's grill theory, analytic expressions for the wave electric field in the slab model of an inhomogeneous cold plasma have been derived. It is shown that a strong wave electric field will be generated in the plasma edge by injecting LH wave of the power in MW magnitude, and this electric field will induce a poloidal rotation with a sheared poloidal velocity.展开更多
According to the action law of gas flow during injecting inert gases as the research main line, and hydromechanics and thermodynamics theories, the characteristic of gas delamination that was caused by injecting inert...According to the action law of gas flow during injecting inert gases as the research main line, and hydromechanics and thermodynamics theories, the characteristic of gas delamination that was caused by injecting inert gases to closed fire zone was analyzed. The criterion was brought forward, which could scale disappearing probability of turbulent state. Formation mechanism of gas layer in turbulent state was discussed primarily. Simultaneously, the condition was pointed out, which could makc the gas in turbulent state by injecting different gases. The mathematical model about dynamic changes of oxygen and methane concentration in the process of injecting gases was erected. The mixture mechanism about injecting different flow inert gases and flammable gas layer in closed fire zone was revealed.展开更多
This article describes a sampling and estimation scheme for estimating the size of an injecting drug user (IDU) population by combining classical sampling and respondent-driven sampling procedures. It is designed to u...This article describes a sampling and estimation scheme for estimating the size of an injecting drug user (IDU) population by combining classical sampling and respondent-driven sampling procedures. It is designed to use the information from harm reduction programs, especially, Needle Exchange Programs (NEPs). The approach involves using respondent-driven sampling design to collect a sample of injecting drug users who appear at site of NEP in a certain period of time and to obtain retrospective self-report data on the number of friends among the IDUs and number of needles exchanged for each sampled injecting drug user. A methodology is developed to estimate the size of injecting drug users who have ever used the NEP during the fixed period of time, and which allows us to estimate the proportion of injecting drug users in using NEP. The size of the IDU population is estimated by dividing the total number of IDUs who using NEPs during the period of time by the estimated proportion of IDUs in the group. The technique holds promise for providing data needed to answer questions such as “What is the size of an IDU population in a city?” and “Is that size changing?” and better understand the dynamics of the IDU population. The methodology described here can also be used to estimate size of other hard-to-reach population by using information from harm reduction programs.展开更多
Recent interest by physicists in social networks and disease transmission factors has prompted debate over the topology of degree distributions in sexual networks. Social network researchers have been critical of “sc...Recent interest by physicists in social networks and disease transmission factors has prompted debate over the topology of degree distributions in sexual networks. Social network researchers have been critical of “scale-free” Barabasi-Albert approaches, and largely rejected the preferential attachment, “rich-get-richer” assumptions that underlie that model. Instead, research on sexual networks has pointed to the importance of homophily and local sexual norms in dictating degree distributions, and thus disease transmission thresholds. Injecting Drug User (IDU) network topologies may differ from the emerging models of sexual networks, however. Degree distribution analysis of a Brooklyn, NY, IDU network indicates a different topology than the spanning tree configurations discussed for sexual networks, instead featuring comparatively short cycles and high concurrency. Our findings suggest that IDU networks do in some ways conform to a “scale-free” topology, and thus may represent “reservoirs” of potential infection despite seemingly low transmission thresholds.展开更多
The flow structure of the vortex cooling is asymmetrical compared to the traditional gas turbine leading edge cooling,such as the impingement cooling and the axial flow cooling.This asymmetrical property will affect t...The flow structure of the vortex cooling is asymmetrical compared to the traditional gas turbine leading edge cooling,such as the impingement cooling and the axial flow cooling.This asymmetrical property will affect the cooling performance in the blade leading edge,whereas such effects are not found in most of the studies on vortex cooling due to the neglect of the mainstream flow in the airfoil channel.This study involves the mainstream flow field and the rotational effects based on the profile of the GE E3 blade to reveal the mechanism of the asymmetrical flow structure effects.The nozzle position on the characteristics of the vortex and film composite cooling in the turbine rotating blade leading edge is numerically investigated.The cool-ant injecting nozzles are set at the side of the pressure surface(PS-side-in)vs.that is set at the side of the suction surface(SS-side-in)to compare the cooling characteristics at the rotating speed range of 0–4000 rpm with fluid and thermal conjugate approach.Results show that the nozzle position presents different influences under low and higher rotational speeds.As for the mainstream flow,rotation makes the stagnation line move from the pressure surface side to the suction surface side,which changes the coolant film attachment on the blade leading edge surface.The position of nozzles,however,indicates limited influence on the coolant film flow.As for the internal channel vortex flow characteristics,the coolant injected from the nozzles forms a high-velocity region near the target wall,which brings about enhancing convective heat transfer.The flow direction of the vortex flow near the internal channel wall is opposite and aligns with the direction of Coriolis force in both the PS-side-in and SS-side-in,respectively.Therefore,the Coriolis force augments the convective heat transfer intensity of the vortex cooling in the internal channel in SS-side-in while weakening the internal heat transfer in PS-side-in.Such effects become more intense with higher rotational speed.The blade surface temperature decreases as the Coriolis force increases the internal heat transfer intensity.The SS-side-in suggests a superior composite cooling performance under the relatively higher rotating speed.The SS-side-in structure is recommended in the gas turbine blade leading edge running at a higher rotating speed.展开更多
BACKGROUND: Previous researches found that animal models with Parkinson disease (PD) could be established by injecting 6-hydroxydopamine (6-OHDA) into medial forebrain bundle (MFB), substantia nigra compacta (...BACKGROUND: Previous researches found that animal models with Parkinson disease (PD) could be established by injecting 6-hydroxydopamine (6-OHDA) into medial forebrain bundle (MFB), substantia nigra compacta (SNC) and caudate-putamen complex (CPU) of the nigrostriatal pathway. OBJECTIVE : To compare behavioral, biochemica 6-OHDA injections in the areas of MFB, SNC and DESIGN: Controlled observational study and histological properties of these rats undergoing the CPU respectively. SEI-IING: Department of Neurology, First Affiliated Hospital of Guangxi Medical University MATERIALS: A total of 64 adult female SD rats weighing 180-230 g were provided by the Animal Experimental Center of Guangxi Medical University. 6-OHDA (Sigma Company, USA); Brain solid positioner (Standard model 51600, Stoelting Co., IL, USA); rotational monitoring of little animal (type QL-1, USA); high liquid chromatography (HLC, Waters Company). METHOOS: The experiment was carried out in the Medical Experimental Center of Guangxi Medical University from February to December 2005. ① According to digital table, 64 SD rats were divided into MFB group, SNC group, CPU group and control group with 16 in each group. On the basis of the brain atlas of Paxinos, rats in the first three groups were injected with 5 μL 6-OHDA into right MFB (0 mm of line of incisor tooth, A/P 4.4 mm, L/R 1.2 mm, ON -7.8 mm), SNC (line of incisor tooth just equal to horizon, A/P -4.8 mm, L/R 1.6 mm, ON -7.8 mm) and CPU (0 mm of line of incisor tooth, A/P 1.2 mm, L/R 2.7 mm, ON -5.4 mm), respectively. The rats in control group were injected with 5 μL ascorbic acid solution (2 g/L). One week after operation, 0.1 g/L apomorphine (Apo, 0.05 mg/kg) was subcutaneously injected into neck and then rotational behavior induced by Apo was recorded once a week for 8 weeks. The PD models were considered successful only when rotational times more than or equal to 7 times per minute. Eight weeks after operation, micro-perfusion was used to obtain micro-perfusate in bilateral CPU and contents of 3,4-dihydroxyphenylacetic acid (3,4-DOPAC) and homovanillic acid (HVA) were also measured. In addition, amount of tyrosine hydroxylase positive cells (TH*) in SNC was counted with immuno- histochemical staining. MAIN OUTCOME MEASURES : ① Successful rate of PD models; ② contents of dopamine and its metabolite in MFB, SNC and CPU groups and TH* amount. RESULTS: All 64 SD rats were involved in the final analysis. ③ Successful rate and rotational behavior: One week after operation, there were 6 successful models both in SNC and MFB groups; in the 2^nd week, there were 6 both in SNC and MFB groups and 1 in CPU group; in the 3^nd week, there were 1 in MFB group and 3 in CPU group; in the 4^nd week, there were 3 in CPU group. Otherwise, no successful case was found out in the next 3 weeks. Abnormal rotational behavior was not observed in control group. Four weeks after operation, successful rates were 81% (13/16) in MFB group, 75% (12/16) in SNC group and 44% (7/16) in CPU group.② Contents of 3, 4-DOPAC and HVA: Eight weeks after operation, contents in the SNC area of the injured side were lower than those on non-lesion side (P 〈 0.01).③Changes of TH+ amount: Eight weeks after operation, TH+ amount in the SNC area of the lesion side was lower than that on non-lesion side (P 〈 0.01 ). CONCLUSION: Injecting 6-OHDA into MFB, SNC and CPU can damage dopaminergic cells and establish successful PD models.展开更多
On the basis of the mechanism study of injecting clay grouts into overlying strata, the clay grouts are researched in greater detail from three aspects. The flowing state of clay grouts in the strata——the pattern of...On the basis of the mechanism study of injecting clay grouts into overlying strata, the clay grouts are researched in greater detail from three aspects. The flowing state of clay grouts in the strata——the pattern of different direction flowing around a point source is advanced and the flowing equation is put forward which is correspond with experiment result, and the corresponding mechanical model is set up which has its formulistic study, and the function of clay grouts is also discussed after the water in it has been lost, at the same time the concept of similar rock in effective supporting zone is given. It would draw great positive inspiration from what studied in this paper for studying on drawing down the surface subsidence by injecting.展开更多
Injecting water into the main pipeline is a common method to prevent the ammonium salt corrosion in hydrogenation units.The use of spray nozzle can enhance the effects of washing ammonium salt and reduce the risk of a...Injecting water into the main pipeline is a common method to prevent the ammonium salt corrosion in hydrogenation units.The use of spray nozzle can enhance the effects of washing ammonium salt and reduce the risk of ammonium salt corrosion.The droplet atomization and evaporation model were used to investigate the mixing process of injecting water and gas-oil mixture in a high-pressure environment.The effects of some key parameters including fluid velocity,temperature,and droplet volume fraction on the mixing and vaporization process were analyzed.Numerical simulation results show that with the increase of injecting water flow rate,the fluid velocity increases and the temperature decreases continuously.When the mass flow rate of injecting water is 1.5 t/h,the droplet has the maximum evaporation efficiency and the volume fraction reaches a minimum value.Besides,with the increase of atomization angle and droplet size,the mean velocity and the temperature of fluid decrease continuously.The increase of atomization angle or the decrease of droplet size will accelerate the evaporation process of droplets and reduce the droplet volume fraction,which indicates that the droplet slip velocity and the contact area are the key factors affecting the droplet evaporation rate.展开更多
After many years of development, die casting technology of metallic materials has been matured. In this paper,the lower-support and its injecting system were created with commercial software. And then the simulation s...After many years of development, die casting technology of metallic materials has been matured. In this paper,the lower-support and its injecting system were created with commercial software. And then the simulation softwareFLOW3D was applied to study the flow behavior of the melt during injection filling process. Both temperature field anddefect distribution were simulated. Based on these results, the better injecting system with two additional overflows wasadopted.展开更多
The performance of polymer light emitting devices(PLEDs)based on polyvinyl carbazole(PVK)is improved by introducing a nanoscale interfacial thin layer,made of poly(ethylene oxide)(PEO),between the calcium cathode and ...The performance of polymer light emitting devices(PLEDs)based on polyvinyl carbazole(PVK)is improved by introducing a nanoscale interfacial thin layer,made of poly(ethylene oxide)(PEO),between the calcium cathode and the PVK emissive layer.It is believed that the PEO layer plays a key role in enhancing the device performance.In comparison to the device with Ca/Al as the cathode,the performance of the PLED with PEO/Ca/Al cathode,including the driving voltage,luminance efficiency is significantly improved.These improvements are attributed to the introduction of a thin layer of PEO that can lower the interfacial barrier and facilitate electron injection.展开更多
Objective The mode of human immunodeficiency virus(HIV) transmission via injection drug use(IDU)still exists, and the recent shift in IDU-related transmission of HIV infection is largely unknown. The purpose of this s...Objective The mode of human immunodeficiency virus(HIV) transmission via injection drug use(IDU)still exists, and the recent shift in IDU-related transmission of HIV infection is largely unknown. The purpose of this study was to analyze the spatiotemporal sources and dynamics of HIV-1 transmission through IDU in Guangxi.Methods We performed a molecular epidemiological investigation of infections across Guangxi from2009 to 2019. Phylogenetic and Bayesian time-geographic analyses of HIV-1 sequences were performed to confirm the characteristics of transmission between IDUs in combination with epidemiological data.Results Among the 535 subjects, CRF08_BC(57.4%), CRF01_AE(28.4%), and CRF07_BC(10.7%) were the top 3 HIV strains;72.6% of infections were linked to other provinces in the transmission network;93.6% of sequence-transmitted strains were locally endemic, with the rest coming from other provinces,predominantly Guangdong and Yunnan;92.1% of the HIV transmission among people who inject drugs tended to be transmitted between HIV-positive IDUs.Conclusion HIV recombinants were high diversity, and circulating local strains were the transmission sources among IDUs in Guangxi. However, there were still cases of IDUs linked to other provinces.Coverage of traditional prevention strategies should be expanded, and inter-provincial collaboration between Guangxi, Yunnan, and Guangdong provinces should be strengthened.展开更多
In 1970s,sedatives or spasmolytics needed to beadministered 30 minutes prior to performingenteroscopy to relieve abdominal colic during theexamination.Owing to the improvement in operatingskills,such drugs are no more...In 1970s,sedatives or spasmolytics needed to beadministered 30 minutes prior to performingenteroscopy to relieve abdominal colic during theexamination.Owing to the improvement in operatingskills,such drugs are no more used today.However,anumber of patients still suffer from abdominal coliccaused by irritated colon in the process ofenteroscopy.For severe cases,the operator has nochoice but to suspend the examination.To find a展开更多
The injection molding products with different volume ratios of ZrO2 ceramic powder to 316L stainless steel powder were prepared. Properties and structure of the products were characterized by X-ray diffraction(XRD),...The injection molding products with different volume ratios of ZrO2 ceramic powder to 316L stainless steel powder were prepared. Properties and structure of the products were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM) and transmission electron microscope (TEM). The results show that the compressive stress exists in the products and the bend strength reaches 300MPa. ZrO2 phase and stainless steel phase are uniform in samples. The toughness of ceramic increases with the increasing the content of stainless steel. Through TEM study of the interface, some crystalline orientation relationships are determined.展开更多
Transport structures built throughout the period from 1960 to 1980 in permafrost regions based on the principle of permafrost preservation are subject to deformations.In many cases,the reason is a gradual change in te...Transport structures built throughout the period from 1960 to 1980 in permafrost regions based on the principle of permafrost preservation are subject to deformations.In many cases,the reason is a gradual change in temperature and their subgrade condition within the active zone due to the structures'technogenic impact.Design solutions for the fifty-year-old structures fail to ensure in all cases their reliable operation at the present time.The greatest danger to the reliable operation of railway lines in cold regions is uneven deformations of bridges,which are barrier places.Therefore,the solution to this problem is urgent especially due to the necessity of increase carrying capacity.The purpose of this study is to increase reliability of bridge operation in cold regions through strengthening the subgrade by reinforcement with injection of solidifying solutions.The problem of uneven deformations due to permafrost degradation is considered using the example of a railway bridge located in the northern line of the Krasnoyarsk railway.Deformations of the bridge abutments began immediately after the construction was completed and the bridge was open for traffic-since 1977.Permafrost degradation was developing more actively straight under the abutments due to higher thermal conductivity of the piles concrete.Notably,thawing intensity of frozen soils under the bridge abutments is uneven due to its orientation to the cardinal points.The analysis of archive materials and results of the geodetic survey made it possible to systematize the features of augmenting deformations of each abutment over time.The engineering-geological survey with drilling wells near the abutments ensured determination of soil characteristics,both in the frozen and thawed states.Thermometric wells were arranged to measure temperatures.The analysis and systematization of the data obtained allowed us to develop geotechnical models for each abutment of the bridge.The peculiarity of these models is allowance for changes in the strength and deformation characteristics of the soil calculated layers depending on changes in temperature and the soil condition.Thus,different calculated geological elements with the corresponding strength and deformation characteristics were identified in the soil layers of the same origin.The analysis of the systematized geodetic data allowed us to confirm adequacy of the developed geotechnical models.Studies carried out using geotechnical models made it possible to predict improvement of physical and mechanical characteristics of the subgrade to prevent further growth deformations of the bridge abutments.The method of reinforcement by injection is proposed.Injecting a solution under pressure leads to strengthening of weakened thawed soils and improving their physical and mechanical properties.This research theoretically substantiates and develops the geotechnical models of the reinforced pier footing of bridge abutments by injection of solidifying solutions.The models take into account the reinforcement parameters and elements for the case in question.The influence of reinforcement on the change in physical and mechanical properties of the soil mass is determined.展开更多
The response of a bipolar transistor (BJT) under a square-wave electromagnetic pulse (EMP) with different injecting voltages is investigated. Adopting the curve fitting method, the relationship between the burnout...The response of a bipolar transistor (BJT) under a square-wave electromagnetic pulse (EMP) with different injecting voltages is investigated. Adopting the curve fitting method, the relationship between the burnout time, the damage energy and the injecting voltage is obtained. Research shows that the damage energy is not a constant value, but changes with the injecting voltage level. By use of the device simulator Medici, the internal behavior of the burned device is analyzed. Simulation results indicate that the variation of the damage energy with injecting voltage is caused by the distribution change of hot spot position under different injection levels. Therefore, the traditional way to evaluate the trade-off between the burnout time and the injecting voltage is not comprehensive due to the variation of the damage energy.展开更多
BACKGROUND Intramuscular corticosteroid injection may cause adverse effects such as dermal and/or subcutaneous atrophy,alopecia,hypopigmentation,and hyperpigmentation.Although cutaneous atrophy can spontaneously resol...BACKGROUND Intramuscular corticosteroid injection may cause adverse effects such as dermal and/or subcutaneous atrophy,alopecia,hypopigmentation,and hyperpigmentation.Although cutaneous atrophy can spontaneously resolve,several treatment options have been suggested for this condition.CASE SUMMARY In this paper,we report a case of corticosteroid injection induced lipoatrophy treated with autologous whole blood(AWB)injection,as the condition had been unresponsive to fractional laser therapy.A 29-year-old female patient visited the dermatology clinic complaining of skin depression on her right buttock area,which had appeared six months earlier.There had been only subtle improvement at the margins after fractional CO_(2) laser treatment;therefore,after obtaining informed consent from the patient,AWB treatment was initiated.One month after the first AWB injection,the size and depth of the lesion had noticeably improved,and a slight improvement was also observed in discoloration.CONCLUSION Close observation is the initial treatment of choice for steroid induced skin atrophy;however,for patients in need of immediate cosmetic improvement,AWB injection may be a safe and cost-effective alternative.展开更多
China continues to drive up consumption to boost the economy As China steps into the Year of the Pig,which symbolizes good fortune,it is also striving to achieve prosperity commensurate with its implications.Before th...China continues to drive up consumption to boost the economy As China steps into the Year of the Pig,which symbolizes good fortune,it is also striving to achieve prosperity commensurate with its implications.Before the Lunar New Year on February 5.展开更多
Primary rabbit skin fibroblasts (RSF) containing lacZ reporter gene or human clotting factor IX (hFIX) cDNA could long termly exist and be expressed after being implanted in rabbit muscles. Among them, the beta glacto...Primary rabbit skin fibroblasts (RSF) containing lacZ reporter gene or human clotting factor IX (hFIX) cDNA could long termly exist and be expressed after being implanted in rabbit muscles. Among them, the beta glactosidase expression lasted at least 3 months, and hFIX expression lasted 1 month. These results will be helpful to organically combine the advantages of both skin fibroblasts and muscle, and provide a new way for somatic gene therapy of hemophilia B and other genetic diseases.展开更多
基金Supported by National High Technology Research and Development (863) Program of China (2011AA100607)National Transgenic Major Project of China (2010ZX08007003)~~
文摘[Objective] This study aimed to investigate the feasibility of transgenesis by injecting exogenous DNA into zygote cytoplasm of Buffalo. [Method] Buffalo oocytes were randomly divided into two groups 20-22 h after in vitro maturation. One group of oocytes was introduced with about 7.5 pl of 50 μg/ml DNA solution containing linear EGFP fragment by cytoplasmic injection 7-10 h or 18-20 h after in vitro fertilization (IVF); the other group of oocytes was introduced with mixture of a single buffalo sperm and about 7.5 pl of 50 μg/ml DNA solution containing linear EGFP fragment by cytoplasmic injection (generally called ICSI-Mediated Gene Transfer, ICSI-Tr). Expression of exogenous DNA was observed and recorded during the process of embryonic development. [Result] Early embryonic gene expression efficiency and blastocyst gene expression efficiency in IVF injection group showed no significant difference compared with that in ICSI-Tr group (P0.05). In addition, the cleavage rate and early embryonic gene expression efficiency in IVF injection group were significantly higher with injection at 7-10 h post IVF than that at 18-20 h post IVF (P0.05). [Conclusion] These results indicate that transgenic buffalo embryos can be generated by injecting exogenous DNA into cytoplasm of IVF oocytes, and the optimal injection time is 7-10 h post IVF.
文摘On the basis of detailed analysis of a novel harmonic counteracting method which can be used to effectively compensate the supply line harmonic currents of a passive single phase diode bridge rectifier, this paper presents two simpler single phase diode bridge rectifier configurations and their alternatives which can achieve low supply line current THD(total harmonic distortion) too. Moreover, this paper also proposes a few passive hamonic counteracting networks for multi single phase rectifiers which are connected in parallel.
基金the Nuclear Science Foundation under Grant! No. H7196c0302.
文摘The poloidal rotation of the magnetized edge plasma in tokamak driven by the ponderomotive force which is generated by injecting lower hybrid wave(LHW) electric field has been studied. The LHW is launched from a waveguide in the plasma edge, and by Brambilla's grill theory, analytic expressions for the wave electric field in the slab model of an inhomogeneous cold plasma have been derived. It is shown that a strong wave electric field will be generated in the plasma edge by injecting LH wave of the power in MW magnitude, and this electric field will induce a poloidal rotation with a sheared poloidal velocity.
文摘According to the action law of gas flow during injecting inert gases as the research main line, and hydromechanics and thermodynamics theories, the characteristic of gas delamination that was caused by injecting inert gases to closed fire zone was analyzed. The criterion was brought forward, which could scale disappearing probability of turbulent state. Formation mechanism of gas layer in turbulent state was discussed primarily. Simultaneously, the condition was pointed out, which could makc the gas in turbulent state by injecting different gases. The mathematical model about dynamic changes of oxygen and methane concentration in the process of injecting gases was erected. The mixture mechanism about injecting different flow inert gases and flammable gas layer in closed fire zone was revealed.
文摘This article describes a sampling and estimation scheme for estimating the size of an injecting drug user (IDU) population by combining classical sampling and respondent-driven sampling procedures. It is designed to use the information from harm reduction programs, especially, Needle Exchange Programs (NEPs). The approach involves using respondent-driven sampling design to collect a sample of injecting drug users who appear at site of NEP in a certain period of time and to obtain retrospective self-report data on the number of friends among the IDUs and number of needles exchanged for each sampled injecting drug user. A methodology is developed to estimate the size of injecting drug users who have ever used the NEP during the fixed period of time, and which allows us to estimate the proportion of injecting drug users in using NEP. The size of the IDU population is estimated by dividing the total number of IDUs who using NEPs during the period of time by the estimated proportion of IDUs in the group. The technique holds promise for providing data needed to answer questions such as “What is the size of an IDU population in a city?” and “Is that size changing?” and better understand the dynamics of the IDU population. The methodology described here can also be used to estimate size of other hard-to-reach population by using information from harm reduction programs.
文摘Recent interest by physicists in social networks and disease transmission factors has prompted debate over the topology of degree distributions in sexual networks. Social network researchers have been critical of “scale-free” Barabasi-Albert approaches, and largely rejected the preferential attachment, “rich-get-richer” assumptions that underlie that model. Instead, research on sexual networks has pointed to the importance of homophily and local sexual norms in dictating degree distributions, and thus disease transmission thresholds. Injecting Drug User (IDU) network topologies may differ from the emerging models of sexual networks, however. Degree distribution analysis of a Brooklyn, NY, IDU network indicates a different topology than the spanning tree configurations discussed for sexual networks, instead featuring comparatively short cycles and high concurrency. Our findings suggest that IDU networks do in some ways conform to a “scale-free” topology, and thus may represent “reservoirs” of potential infection despite seemingly low transmission thresholds.
基金supported by the National Science and Technology Major Project under Grant (2017-I-0009-0010).
文摘The flow structure of the vortex cooling is asymmetrical compared to the traditional gas turbine leading edge cooling,such as the impingement cooling and the axial flow cooling.This asymmetrical property will affect the cooling performance in the blade leading edge,whereas such effects are not found in most of the studies on vortex cooling due to the neglect of the mainstream flow in the airfoil channel.This study involves the mainstream flow field and the rotational effects based on the profile of the GE E3 blade to reveal the mechanism of the asymmetrical flow structure effects.The nozzle position on the characteristics of the vortex and film composite cooling in the turbine rotating blade leading edge is numerically investigated.The cool-ant injecting nozzles are set at the side of the pressure surface(PS-side-in)vs.that is set at the side of the suction surface(SS-side-in)to compare the cooling characteristics at the rotating speed range of 0–4000 rpm with fluid and thermal conjugate approach.Results show that the nozzle position presents different influences under low and higher rotational speeds.As for the mainstream flow,rotation makes the stagnation line move from the pressure surface side to the suction surface side,which changes the coolant film attachment on the blade leading edge surface.The position of nozzles,however,indicates limited influence on the coolant film flow.As for the internal channel vortex flow characteristics,the coolant injected from the nozzles forms a high-velocity region near the target wall,which brings about enhancing convective heat transfer.The flow direction of the vortex flow near the internal channel wall is opposite and aligns with the direction of Coriolis force in both the PS-side-in and SS-side-in,respectively.Therefore,the Coriolis force augments the convective heat transfer intensity of the vortex cooling in the internal channel in SS-side-in while weakening the internal heat transfer in PS-side-in.Such effects become more intense with higher rotational speed.The blade surface temperature decreases as the Coriolis force increases the internal heat transfer intensity.The SS-side-in suggests a superior composite cooling performance under the relatively higher rotating speed.The SS-side-in structure is recommended in the gas turbine blade leading edge running at a higher rotating speed.
基金Foundation for the Returned Overseas Chinese Scholars of Guangxi Zhuang Autonomous Region, No. 0448017
文摘BACKGROUND: Previous researches found that animal models with Parkinson disease (PD) could be established by injecting 6-hydroxydopamine (6-OHDA) into medial forebrain bundle (MFB), substantia nigra compacta (SNC) and caudate-putamen complex (CPU) of the nigrostriatal pathway. OBJECTIVE : To compare behavioral, biochemica 6-OHDA injections in the areas of MFB, SNC and DESIGN: Controlled observational study and histological properties of these rats undergoing the CPU respectively. SEI-IING: Department of Neurology, First Affiliated Hospital of Guangxi Medical University MATERIALS: A total of 64 adult female SD rats weighing 180-230 g were provided by the Animal Experimental Center of Guangxi Medical University. 6-OHDA (Sigma Company, USA); Brain solid positioner (Standard model 51600, Stoelting Co., IL, USA); rotational monitoring of little animal (type QL-1, USA); high liquid chromatography (HLC, Waters Company). METHOOS: The experiment was carried out in the Medical Experimental Center of Guangxi Medical University from February to December 2005. ① According to digital table, 64 SD rats were divided into MFB group, SNC group, CPU group and control group with 16 in each group. On the basis of the brain atlas of Paxinos, rats in the first three groups were injected with 5 μL 6-OHDA into right MFB (0 mm of line of incisor tooth, A/P 4.4 mm, L/R 1.2 mm, ON -7.8 mm), SNC (line of incisor tooth just equal to horizon, A/P -4.8 mm, L/R 1.6 mm, ON -7.8 mm) and CPU (0 mm of line of incisor tooth, A/P 1.2 mm, L/R 2.7 mm, ON -5.4 mm), respectively. The rats in control group were injected with 5 μL ascorbic acid solution (2 g/L). One week after operation, 0.1 g/L apomorphine (Apo, 0.05 mg/kg) was subcutaneously injected into neck and then rotational behavior induced by Apo was recorded once a week for 8 weeks. The PD models were considered successful only when rotational times more than or equal to 7 times per minute. Eight weeks after operation, micro-perfusion was used to obtain micro-perfusate in bilateral CPU and contents of 3,4-dihydroxyphenylacetic acid (3,4-DOPAC) and homovanillic acid (HVA) were also measured. In addition, amount of tyrosine hydroxylase positive cells (TH*) in SNC was counted with immuno- histochemical staining. MAIN OUTCOME MEASURES : ① Successful rate of PD models; ② contents of dopamine and its metabolite in MFB, SNC and CPU groups and TH* amount. RESULTS: All 64 SD rats were involved in the final analysis. ③ Successful rate and rotational behavior: One week after operation, there were 6 successful models both in SNC and MFB groups; in the 2^nd week, there were 6 both in SNC and MFB groups and 1 in CPU group; in the 3^nd week, there were 1 in MFB group and 3 in CPU group; in the 4^nd week, there were 3 in CPU group. Otherwise, no successful case was found out in the next 3 weeks. Abnormal rotational behavior was not observed in control group. Four weeks after operation, successful rates were 81% (13/16) in MFB group, 75% (12/16) in SNC group and 44% (7/16) in CPU group.② Contents of 3, 4-DOPAC and HVA: Eight weeks after operation, contents in the SNC area of the injured side were lower than those on non-lesion side (P 〈 0.01).③Changes of TH+ amount: Eight weeks after operation, TH+ amount in the SNC area of the lesion side was lower than that on non-lesion side (P 〈 0.01 ). CONCLUSION: Injecting 6-OHDA into MFB, SNC and CPU can damage dopaminergic cells and establish successful PD models.
文摘On the basis of the mechanism study of injecting clay grouts into overlying strata, the clay grouts are researched in greater detail from three aspects. The flowing state of clay grouts in the strata——the pattern of different direction flowing around a point source is advanced and the flowing equation is put forward which is correspond with experiment result, and the corresponding mechanical model is set up which has its formulistic study, and the function of clay grouts is also discussed after the water in it has been lost, at the same time the concept of similar rock in effective supporting zone is given. It would draw great positive inspiration from what studied in this paper for studying on drawing down the surface subsidence by injecting.
基金The authors acknowledge supports from the National Natural Science Foundation of China(Grant No.51806198,No.U1909216,No.52176048,No.51876194)the Zhejiang Provincial Natural Science Foundation(Grant No.LY21E060011)the Fundamental Research Funds of Zhejiang Sci-Tech University(Grant No.2021Q020).
文摘Injecting water into the main pipeline is a common method to prevent the ammonium salt corrosion in hydrogenation units.The use of spray nozzle can enhance the effects of washing ammonium salt and reduce the risk of ammonium salt corrosion.The droplet atomization and evaporation model were used to investigate the mixing process of injecting water and gas-oil mixture in a high-pressure environment.The effects of some key parameters including fluid velocity,temperature,and droplet volume fraction on the mixing and vaporization process were analyzed.Numerical simulation results show that with the increase of injecting water flow rate,the fluid velocity increases and the temperature decreases continuously.When the mass flow rate of injecting water is 1.5 t/h,the droplet has the maximum evaporation efficiency and the volume fraction reaches a minimum value.Besides,with the increase of atomization angle and droplet size,the mean velocity and the temperature of fluid decrease continuously.The increase of atomization angle or the decrease of droplet size will accelerate the evaporation process of droplets and reduce the droplet volume fraction,which indicates that the droplet slip velocity and the contact area are the key factors affecting the droplet evaporation rate.
文摘After many years of development, die casting technology of metallic materials has been matured. In this paper,the lower-support and its injecting system were created with commercial software. And then the simulation softwareFLOW3D was applied to study the flow behavior of the melt during injection filling process. Both temperature field anddefect distribution were simulated. Based on these results, the better injecting system with two additional overflows wasadopted.
基金the Office of R&D,National Cheng Kung University,Taiwan
文摘The performance of polymer light emitting devices(PLEDs)based on polyvinyl carbazole(PVK)is improved by introducing a nanoscale interfacial thin layer,made of poly(ethylene oxide)(PEO),between the calcium cathode and the PVK emissive layer.It is believed that the PEO layer plays a key role in enhancing the device performance.In comparison to the device with Ca/Al as the cathode,the performance of the PLED with PEO/Ca/Al cathode,including the driving voltage,luminance efficiency is significantly improved.These improvements are attributed to the introduction of a thin layer of PEO that can lower the interfacial barrier and facilitate electron injection.
基金National Natural Science Foundation of China [grant no. 82060610]National Natural Science Foundation of China [grant no. 82103899]+2 种基金Guangxi Scientific and Technological Key Project[Gui Ke AB19245038]Guangxi Scientific and Technological Key Project [Guike 2022AC23005, 2022AC20031,2022JJA141110]Science and Technology Project of Nanning [20223051]。
文摘Objective The mode of human immunodeficiency virus(HIV) transmission via injection drug use(IDU)still exists, and the recent shift in IDU-related transmission of HIV infection is largely unknown. The purpose of this study was to analyze the spatiotemporal sources and dynamics of HIV-1 transmission through IDU in Guangxi.Methods We performed a molecular epidemiological investigation of infections across Guangxi from2009 to 2019. Phylogenetic and Bayesian time-geographic analyses of HIV-1 sequences were performed to confirm the characteristics of transmission between IDUs in combination with epidemiological data.Results Among the 535 subjects, CRF08_BC(57.4%), CRF01_AE(28.4%), and CRF07_BC(10.7%) were the top 3 HIV strains;72.6% of infections were linked to other provinces in the transmission network;93.6% of sequence-transmitted strains were locally endemic, with the rest coming from other provinces,predominantly Guangdong and Yunnan;92.1% of the HIV transmission among people who inject drugs tended to be transmitted between HIV-positive IDUs.Conclusion HIV recombinants were high diversity, and circulating local strains were the transmission sources among IDUs in Guangxi. However, there were still cases of IDUs linked to other provinces.Coverage of traditional prevention strategies should be expanded, and inter-provincial collaboration between Guangxi, Yunnan, and Guangdong provinces should be strengthened.
文摘In 1970s,sedatives or spasmolytics needed to beadministered 30 minutes prior to performingenteroscopy to relieve abdominal colic during theexamination.Owing to the improvement in operatingskills,such drugs are no more used today.However,anumber of patients still suffer from abdominal coliccaused by irritated colon in the process ofenteroscopy.For severe cases,the operator has nochoice but to suspend the examination.To find a
文摘The injection molding products with different volume ratios of ZrO2 ceramic powder to 316L stainless steel powder were prepared. Properties and structure of the products were characterized by X-ray diffraction(XRD), scanning electron microscope(SEM) and transmission electron microscope (TEM). The results show that the compressive stress exists in the products and the bend strength reaches 300MPa. ZrO2 phase and stainless steel phase are uniform in samples. The toughness of ceramic increases with the increasing the content of stainless steel. Through TEM study of the interface, some crystalline orientation relationships are determined.
文摘Transport structures built throughout the period from 1960 to 1980 in permafrost regions based on the principle of permafrost preservation are subject to deformations.In many cases,the reason is a gradual change in temperature and their subgrade condition within the active zone due to the structures'technogenic impact.Design solutions for the fifty-year-old structures fail to ensure in all cases their reliable operation at the present time.The greatest danger to the reliable operation of railway lines in cold regions is uneven deformations of bridges,which are barrier places.Therefore,the solution to this problem is urgent especially due to the necessity of increase carrying capacity.The purpose of this study is to increase reliability of bridge operation in cold regions through strengthening the subgrade by reinforcement with injection of solidifying solutions.The problem of uneven deformations due to permafrost degradation is considered using the example of a railway bridge located in the northern line of the Krasnoyarsk railway.Deformations of the bridge abutments began immediately after the construction was completed and the bridge was open for traffic-since 1977.Permafrost degradation was developing more actively straight under the abutments due to higher thermal conductivity of the piles concrete.Notably,thawing intensity of frozen soils under the bridge abutments is uneven due to its orientation to the cardinal points.The analysis of archive materials and results of the geodetic survey made it possible to systematize the features of augmenting deformations of each abutment over time.The engineering-geological survey with drilling wells near the abutments ensured determination of soil characteristics,both in the frozen and thawed states.Thermometric wells were arranged to measure temperatures.The analysis and systematization of the data obtained allowed us to develop geotechnical models for each abutment of the bridge.The peculiarity of these models is allowance for changes in the strength and deformation characteristics of the soil calculated layers depending on changes in temperature and the soil condition.Thus,different calculated geological elements with the corresponding strength and deformation characteristics were identified in the soil layers of the same origin.The analysis of the systematized geodetic data allowed us to confirm adequacy of the developed geotechnical models.Studies carried out using geotechnical models made it possible to predict improvement of physical and mechanical characteristics of the subgrade to prevent further growth deformations of the bridge abutments.The method of reinforcement by injection is proposed.Injecting a solution under pressure leads to strengthening of weakened thawed soils and improving their physical and mechanical properties.This research theoretically substantiates and develops the geotechnical models of the reinforced pier footing of bridge abutments by injection of solidifying solutions.The models take into account the reinforcement parameters and elements for the case in question.The influence of reinforcement on the change in physical and mechanical properties of the soil mass is determined.
基金supported by the National Natural Science Foundation of China(No.60776034).
文摘The response of a bipolar transistor (BJT) under a square-wave electromagnetic pulse (EMP) with different injecting voltages is investigated. Adopting the curve fitting method, the relationship between the burnout time, the damage energy and the injecting voltage is obtained. Research shows that the damage energy is not a constant value, but changes with the injecting voltage level. By use of the device simulator Medici, the internal behavior of the burned device is analyzed. Simulation results indicate that the variation of the damage energy with injecting voltage is caused by the distribution change of hot spot position under different injection levels. Therefore, the traditional way to evaluate the trade-off between the burnout time and the injecting voltage is not comprehensive due to the variation of the damage energy.
基金Supported by The New Faculty Research Grant of Pusan National University,2023The Research Grant of the Chungbuk National University in 2023.
文摘BACKGROUND Intramuscular corticosteroid injection may cause adverse effects such as dermal and/or subcutaneous atrophy,alopecia,hypopigmentation,and hyperpigmentation.Although cutaneous atrophy can spontaneously resolve,several treatment options have been suggested for this condition.CASE SUMMARY In this paper,we report a case of corticosteroid injection induced lipoatrophy treated with autologous whole blood(AWB)injection,as the condition had been unresponsive to fractional laser therapy.A 29-year-old female patient visited the dermatology clinic complaining of skin depression on her right buttock area,which had appeared six months earlier.There had been only subtle improvement at the margins after fractional CO_(2) laser treatment;therefore,after obtaining informed consent from the patient,AWB treatment was initiated.One month after the first AWB injection,the size and depth of the lesion had noticeably improved,and a slight improvement was also observed in discoloration.CONCLUSION Close observation is the initial treatment of choice for steroid induced skin atrophy;however,for patients in need of immediate cosmetic improvement,AWB injection may be a safe and cost-effective alternative.
文摘China continues to drive up consumption to boost the economy As China steps into the Year of the Pig,which symbolizes good fortune,it is also striving to achieve prosperity commensurate with its implications.Before the Lunar New Year on February 5.
文摘Primary rabbit skin fibroblasts (RSF) containing lacZ reporter gene or human clotting factor IX (hFIX) cDNA could long termly exist and be expressed after being implanted in rabbit muscles. Among them, the beta glactosidase expression lasted at least 3 months, and hFIX expression lasted 1 month. These results will be helpful to organically combine the advantages of both skin fibroblasts and muscle, and provide a new way for somatic gene therapy of hemophilia B and other genetic diseases.