The aim of this study was to design a cage-like radiotherapy system(CRTS)to further promote the clinical application of noncoplanar radiotherapy.The CRTS comprises two stands,two O-rings,several arc girders,an X-ray h...The aim of this study was to design a cage-like radiotherapy system(CRTS)to further promote the clinical application of noncoplanar radiotherapy.The CRTS comprises two stands,two O-rings,several arc girders,an X-ray head,an imaging subsystem,and a treatment couch.The X-ray head rotates with O-rings around the patient’s body and slides along the arc girder.Compared with the C-arm linear accelerator(C-Linac),the clinically available spatial irradiation angle ranges(SIARs)of the CRTS for the head,chest,and abdomen were 33%,63.6%,and 62.6%larger,respectively.Moreover,according to a preliminary planning comparison based on the dose distribution simulation method,the CRTS achieved much better protection of normal tissue than the C-Linac.Furthermore,the CRTS enabled accurate noncoplanar irradiation without movement of the body being irradiated,allowed automatic control of the movements of different parts without risk of collisions,and provided continuous radiation over an angle that considerably exceeded a full turn.These advantages make CRTS very promising for noncoplanar radiotherapy.展开更多
To investigate the effects of individualised treatment with peginterferon alpha-2a(40 kD)plus ribavirin in Chinese patients with CHC.Methods Total of 297 consecutive Chinese patients were enrolled,including 250 nave c...To investigate the effects of individualised treatment with peginterferon alpha-2a(40 kD)plus ribavirin in Chinese patients with CHC.Methods Total of 297 consecutive Chinese patients were enrolled,including 250 nave cases and 47 cases who were previously treated.Treatment duration was determined according to viral genotypes,prior treatment history and viral responses at week 4,12 and 24.Results Totally,235 patients(79.1%)completed treatment and 186(87.3%)achieved SVR.And 219 out of 289(75.8%)patients achieved HCV RNA negative at week 4(RVR)and 259 of 276(93.8%)at week 12.Among the 164 patients with RVR who completed follow-up,158(96.3%)achieved SVR.Patients with RVR had lower baseline viral loads than patients without RVR(P=0.034).The positive predictive value(PPV)of RVR for SVR was 90.7%(OR 2.10 vs.non-RVR,95%CI:0.50-8.7).Similar outcomes were observed among patients with HCV undetectable at week 12.Conclusions Viral suppression by week 4 is associated with a high rate of treatment success in treatment nave and experienced patients receiving individualized CHC therapy.展开更多
Background: Recent studies reported that patients with coronavirus disease-2019(COVID-19) might have liver injury. However, few data on the combined analysis and change patterns of alanine aminotransferase(ALT), aspar...Background: Recent studies reported that patients with coronavirus disease-2019(COVID-19) might have liver injury. However, few data on the combined analysis and change patterns of alanine aminotransferase(ALT), aspartate aminotransferase(AST) and total bilirubin(TBil) have been shown.Methods: This is a single-center retrospective study. A total of 105 adult patients hospitalized for confirmed COVID-19 in Beijing Ditan Hospital between January 12, and March 17, 2020 were included, and divided into mild group(n=79) and severe group(n=26). We compared liver functional test results between the two groups. Category of ALT change during the disease course was also examined.Results: 56.2%(59/105) of the patients had unnormal ALT, AST, or total TBil throughout the course of the disease, but in 91.4%(96/105) cases the level of ALT, AST or TBil ≤3 fold of the upper limit of normal reference range(ULN). The overall distribution of ALT, AST, and TBil were all significantly difference between mild and severe group(P<0.05). The percentage of the patients with elevated both ALT and AST was 12.7%(10/79) in mild cases vs. 46.2%(12/26) in severe cases(P=0.001). 34.6%(9/26) severe group patients started to have abnormal ALT after admission, and 73.3%(77/105) of all patients had normal ALT before discharge.Conclusions: Elevated liver function index is very common in patients with COVID-19 infection, and the level were less than 3×ULN, but most are reversible. The abnormality of 2 or more indexes is low in the patients with COVID-19, but it is more likely to occur in the severe group.展开更多
Fracture propagation is affected by multi-metal-veins formed by geological diagenesis in shale during the hydraulic fracturing.However,the influence of multi-metal-veins on fractures propagation remains unclear.To sol...Fracture propagation is affected by multi-metal-veins formed by geological diagenesis in shale during the hydraulic fracturing.However,the influence of multi-metal-veins on fractures propagation remains unclear.To solve the problem,based on the semi-circle bending(SCB)test and the extended finite element(XFEM)theory,the interaction between multi-metal-veins and fractures is investigated.The experimental results reveal that the fractures usually deflect at the upper or lower interfaces between metal veins and rocks(e.g.the specimen S-2),which is different from the propagation behavior of fractures in calcite veins.Meanwhile,the fracture toughness of the specimen S-1 is 24.40%higher than that of the specimen S-2,indicating that the increasing of total thickness of multiple metal veins in-creases the resistance to the fracture vertical propagation.The simulation results show that the increasing of the number,total thickness of veins,the modulus difference between veins and rock,the approach angle and the notch angle all increase the resistance of the fracture passing through metal veins.The maximum deviation distance(Dmax)of the fracture decreases with the number of veins,while thickness combination types of metal veins do not affect Dmax.The reduction of the notch angle leads to the more tortuous fracture propagation path.Finally,we propose a new comprehensive fracture network pattern.Fracture networks are divided into two categories,including orthogonal fracture networks and sub-orthogonal fracture networks,and then divided into six sub-categories further.The research results will provide reference for hydraulic fracturing of shale reservoirs containing multi-metal-veins.展开更多
Up to 2022 November,267 pulsars had been discovered in 36 globular clusters(GCs).In this paper,we present our studies on the distribution of GC pulsar parameters and the detection efficiency.The power law relation bet...Up to 2022 November,267 pulsars had been discovered in 36 globular clusters(GCs).In this paper,we present our studies on the distribution of GC pulsar parameters and the detection efficiency.The power law relation between average dispersion measure(■)and dispersion measure difference(ΔDM)of known pulsars in GCs is lgΔDM∝1.52lg■.The sensitivity could be the key to finding more pulsars.As a result,several years after the construction of a large radio telescope facility,the number of known GC pulsars will likely be increased accordingly.We suggest that currently GCs in the southern hemisphere could have higher possibilities for finding new pulsars.展开更多
BACKGROUND Ultrasound is a vital tool for the diagnosis and management of colorectal cancer(CRC).Contrast-enhanced ultrasound(CEUS)is a non-invasive,safe,and cost-effective method for evaluating tumour blood vessels,t...BACKGROUND Ultrasound is a vital tool for the diagnosis and management of colorectal cancer(CRC).Contrast-enhanced ultrasound(CEUS)is a non-invasive,safe,and cost-effective method for evaluating tumour blood vessels,that play a crucial role in tumour growth and progression.AIM To explore CEUS’s role in the quantitative evaluation of CRC blood vessels and their correlation with angiogenesis markers and prognosis.METHODS This study prospectively enrolled 100 patients with CRC confirmed by histo-pathology.All patients received preoperative CEUS examinations.Quantitative parameters,such as peak intensity(PI),time to peak(TTP),and area under the curve(AUC),were derived from time-intensity curve(TIC)analysis.Tumour tissue samples were obtained during surgery and examined immunohistochem-ically to assess the expression of angiogenesis markers,including vascular endo-thelial growth factor(VEGF)and microvessel density(MVD).The correlation between CEUS parameters,angiogenesis markers,and clinicopathological features was evaluated using appropriate statistical tests.RESULTS Quantitative CEUS parameters(PI,TTP,and AUC)showed significant correlations with VEGF expression(P<0.001)and MVD(P<0.001),indicating a strong link between tumour blood vessels and angiogenesis.Increased PI,reduced TTP,and expanded AUC values were significantly related to higher tumour stage(P<0.001),lymph node metastasis(P<0.001),and distant metastasis(P<0.001).Furthermore,these parameters were recognized as independent predictors of overall survival and disease-free survival in multivariate analysis(P<0.001).CONCLUSION CEUS has a high potential in guiding treatment planning and predicting patient outcomes.However,more com-prehensive,multicentre studies are required to validate the clinical utility of CEUS in CRC management.展开更多
BACKGROUND: The availability of novel direct-acting antivirals(DAAs) represents a new era of curative hepatitis C virus(HCV) treatment, with over 95% of patients infected with HCV genotype 1 achieving sustained virolo...BACKGROUND: The availability of novel direct-acting antivirals(DAAs) represents a new era of curative hepatitis C virus(HCV) treatment, with over 95% of patients infected with HCV genotype 1 achieving sustained virological response(SVR). Nevertheless, the majority of patients globally are unable to access these treatments because of cost and infrastructure constraints and, thus, remain untreated and uncured.DATA SOURCE: Relevant articles of peginterferon(Peg IFN)-based treatments in HCV and sofosbuvir-based treatments, simeprevir, daclatasvir/asunaprevir, ritonavir-boosted paritaprevir/ombitasvir/dasabuvir, and grazoprevir/elbasvir, were searched in Pub Med database, including general population and special population.RESULTS: Peg IFN in combination with ribavirin remains an important and relevant option for some patients, achieving SVR rates of up to 79% in genotype 1 and 89% in genotype 2 or 3 infections, which increases for patients with favorable IL28 B genotypes. Triple therapy of DAA plus Peg IFN/ribavirin is effective in treating difficult-to-cure patients infected with HCV genotype 3 or with resistance-associated variants. Owing to its long history in HCV management, the efficacy, tolerability and long-term outcomes associated with Peg IFN alfa-2a are well established and have been validated in largescale studies and in clinical practice for many populations. Furthermore, emerging data show that IFN-induced SVR is associated with lower incidences of hepatocellular carcinoma compared with DAAs. On the contrary, novel DAAs have yet to be studied in special populations, and long-term outcomes, particularly tumor development and recurrence in patients with cirrhosis and/or hepatocellular carcinoma, and reactivation of HBV in dually infected patients, are still unclear.CONCLUSION: In this interferon-free era, Peg IFN-based regimens remain a safe and effective option for selected HCV patients.展开更多
AIM: To examine the association between interferon(IFN) therapy and loss of hepatitis B surface antigen(HBs Ag) in inactive HBs Ag carriers. METHODS: This was a retrospective cohort study in inactive HBs Ag carriers, ...AIM: To examine the association between interferon(IFN) therapy and loss of hepatitis B surface antigen(HBs Ag) in inactive HBs Ag carriers. METHODS: This was a retrospective cohort study in inactive HBs Ag carriers, who were treatment-naive, with a serum HBs Ag level < 100 IU/m L and an undetectable hepatitis B virus(HBV) DNA level(< 100 IU/m L). All the 20 treated patients received subcutaneous PEG-IFN alfa-2a 180 μg/wk for 72 wk and were then followed for 24 wk. There were 40 untreated controls matched with 96 wk of observation. Serum HBs Ag, HBV DNA, and alanine aminotransferases were monitored every 3 mo in the treatment group and every 3-6 mo in the control group. RESULTS: Thirteen(65.0%) of 20 treated patients achieved HBs Ag loss, 12 of whom achieved HBs Ag seroconversion. Mean HBs Ag level in treated patients decreased to 6.69 ± 13.04 IU/m L after 24 wk of treatment from a baseline level of 26.22 ± 33.00 IU/m L. Serum HBV DNA level remained undetectable(< 100 IU/m L) in all treated patients during the study. HBs Ag level of the control group decreased from 25.72 ± 25.58 IU/m L at baseline to 17.11 ± 21.62 IU/m L at week 96(P = 0.108). In the control group, no patient experienced HBs Ag loss/seroconversion, and two(5.0%) developed HBV reactivation.CONCLUSION: IFN treatment results in HBs Ag loss and seroconversion in a considerable proportion of inactive HBs Ag carriers with low HBs Ag concentrations.展开更多
Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness...Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness of reservoir stimulation. Temporary plugging and diverting fracturing(TPDF) is considered to be a potential uniform-stimulation method for creating multiple fractures simultaneously in the oilfield. However, the multi-fracture propagation morphology during TPDF is not clear now. The purpose of this study is to quantitatively investigate the multi-fracture propagation morphology during TPDF through true tri-axial fracturing experiments and CT scanning. Critical parameters such as fracture spacing, number of perforation clusters, the viscosity of fracturing fluid, and the in-situ stress have been investigated. The fracture geometry before and after diversion have been quantitively analyzed based on the two-dimensional CT slices and three-dimensional reconstruction method. The main conclusions are as follows:(1) When injecting the high viscosity fluid or perforating at the location with low in-situ stress, multiple hydraulic fractures would simultaneously propagate. Otherwise, only one hydraulic fracture was created during the initial fracturing stage(IFS) for most tests.(2) The perforation cluster effectiveness(PCE) has increased from 26.62% during the IFS to 88.86% after using diverters.(3) The diverted fracture volume has no apparent correlation with the pressure peak and peak frequency during the diversion fracturing stage(DFS) but is positively correlated with water-work.(4) Four types of plugging behavior in shale could be controlled by adjusting the diverter recipe and diverter injection time, and the plugging behavior includes plugging the natural fracture in the wellbore, plugging the previous hydraulic fractures, plugging the fracture tip and plugging the bedding.展开更多
Background Uncertainty remains regarding the association between body mass index(BMI)and the risk of bleeding in patients with non-valvular atrial fibrillation(NVAF).We aimed to investigate the association between BMI...Background Uncertainty remains regarding the association between body mass index(BMI)and the risk of bleeding in patients with non-valvular atrial fibrillation(NVAF).We aimed to investigate the association between BMI and the risk of bleeding in elderly NVAF patients taking dabigatran.Methods A total of 509 elderly NVAF patients,who were being treated at twelve centers in China from February 2015 to December 2017 and taking dabigatran,were analyzed.The exposure and outcome variables were BMI at baseline and bleeding events within the subsequent six months,respectively.Cox proportional hazards regression analysis was used to evaluate the association between BMI and the risk of bleeding.Moreover,the Cox proportional hazards regression with cubic spline functions and smooth curve fitting was conducted.Results During the six-month follow-up,50 participants experienced bleeding.Every 1 kg/m^2 increase in BMI was associated with a 12%increased risk of bleeding(P=0.021).Compared to those with BMI values in Tertile 1(<22.5 kg/m^2),the adjusted hazard ratio(HR)of bleeding for participants in Tertile 2(22.5–25.3 kg/m^2)and Tertile 3(>25.3 kg/m^2)were 2.71(95%CI:1.02–7.17)and 3.5(95%CI:1.21–8.70),respectively.The Ptrend-value was significant in all models.The adjusted smooth curve showed a linear association between BMI and bleeding.None of the stratified variables showed significant effect modification on the association between BMI and bleeding(Pinteraction>0.05).Conclusions BMI was significantly and positively associated with the risk of bleeding in elderly NVAF patients treated with dabigatran.展开更多
Saliva and blood were collected from two patients who had not received post exposure prophylaxis in the cities of Wenzhou and Xinning respectively. Both patients were confirmed as positive for rabies by detection of r...Saliva and blood were collected from two patients who had not received post exposure prophylaxis in the cities of Wenzhou and Xinning respectively. Both patients were confirmed as positive for rabies by detection of rabies virus specific nucleoprotein antibodies in the sera by Western Blot. However, rabies virus specific RNA was only identified in the saliva collected from the patient in Wenzhou. Furthermore, the isolate Zhejiang Wz0 (H) was obtained by inoculating one-day-old suckling mice. Both nucleoprotein (N) and glycoprotein (G) genes from the isolate were amplified by RT-PCR and sequenced. Phylogenetic analysis indicated that the isolate belonged to classic rabies virus, and shared a higher homology with the street viruses from dogs in the main endemic areas in China and the street virus from dogs in Indonesia than with other known strains. Further comparison of the deduced amino acid sequences between the isolate and the vaccine strains used in China showed that the virus had a higher level of homology with the vaccine strain CTN than with the other vaccine strains (3aG, PV, PM and ERA). In particular, amino acid residues substitutions located in antigenic site Ⅲ in the G protein, which could react with the neutralizing antibodies, were observed. These results suggested that the virus belonged to the classic rabies virus, and both N and G genes diverged from the current vaccine strains used in China at either the nucleotide or the amino acid level.展开更多
Intra-stage multi-cluster temporary plugging and diverting fracturing(ITPF)is one of the fastest-growing techniques to obtain uniform reservoir stimulation in shale gas reservoirs.However,propagation geometries of mul...Intra-stage multi-cluster temporary plugging and diverting fracturing(ITPF)is one of the fastest-growing techniques to obtain uniform reservoir stimulation in shale gas reservoirs.However,propagation geometries of multiple fractures during ITPF are not clear due that the existing numerical models cannot capture the effects of perforation plugging.In this paper,a new three-dimensional FEM based on CZM was developed to investigate multiple planar fracture propagation considering perforation plugging during ITPF.Meanwhile,the fluid pipe element and its subroutine were first developed to realize the flux partitioning before or after perforation plugging.The results showed that the perforation plugging changed the original distribution of the number of perforations in each fracture,thus changing the flux partitioning after perforation plugging,which could eliminate the effect of stress interference between multiple fractures and promote a uniform fluid distribution.The standard deviation of fluid distribution in the perforation plugging case was only 8.48%of that in the non-diversion case.Furthermore,critical plugging parameters have been investigated quantitatively.Specifically,injecting more diverters will create a higher fluid pressure rise in the wellbore,which will increase the risk of wellbore integrity.Comprehensively considering pressure rise and fluid distribution,the number of diverters should be 50%of the total number of perforations(N_(pt)),whose standard deviation of fluid distribution of multiple fractures was lower than those in the cases of injecting 10%N_(pt),30%N_(pt)and 70%N_(pt).The diverters should be injected at an appropriate timing,i.e.40%or 50%of the total fracturing time(tft),whose standard deviation of the fluid distribution was only about 20%of standard deviations in the cases of injecting at20%tftor 70%tft.A single injection with all diverters can maintain high bottom-hole pressure for a longer period and promote a more uniform fluid distribution.The standard deviation of the fluid distribution in the case of a single injection was 43.62%-55.41%of the other cases with multiple injection times.This study provides a meaningful perspective and some optimal plugging parameters on the field design during IPTF.展开更多
This paper presents a new measurement system based on integration method that can provide all-weather dependability and higher precision for the measurement of FAST's feed support system.The measurement system con...This paper presents a new measurement system based on integration method that can provide all-weather dependability and higher precision for the measurement of FAST's feed support system.The measurement system consists of three types of measuring equipments,and a processing software with the core data fusion algorithm.The Strapdown Inertial Navigation System(SINS)can autonomously measure the position,speed and attitude of the carrier.Its own shortcoming is that the measurement data diverge rapidly over time.SINS must combine the Global Positioning System(GPS)and the Total Station(TS)to obtain high-precision measurement data.The Kalman filtering algorithm is adopted for the integration measurement system,which is an optimal algorithm to estimate the measurement errors.A series of tests are carried out to evaluate the performance.For the feed cabin,the maximum RMS of the position is 14.56 mm,the maximum RMS of the attitude is 0.095,these values are less than 15 mm and 0.1°as the precision for measuring the feed cabin.For the Stewart manipulator,the maximum RMS of the position is 2.99 mm,the maximum RMS of the attitude is 0.093°,these values are less than 3 mm and 0.1°as the precision for measuring the Stewart manipulator.As a result,the new measurement meets the requirement of measurement precision for FAST's feed support system.展开更多
蚕 Bombyx 粗腐殖质 i 的茧的黄颜色被三基因控制， Y (黄 haemolymph ) ，我(黄禁止者) 并且 C (外部层的黄茧) 它位于连接分别地组织 2， 9 和 12。利用交叉在上的缺乏在女性，相互的 backcrossed F <SUB>1</SUB>(BC <...蚕 Bombyx 粗腐殖质 i 的茧的黄颜色被三基因控制， Y (黄 haemolymph ) ，我(黄禁止者) 并且 C (外部层的黄茧) 它位于连接分别地组织 2， 9 和 12。利用交叉在上的缺乏在女性，相互的 backcrossed F <SUB>1</SUB>(BC <SUB>1</SUB>) 子孙被用于连接分析并且用蚕紧张 C108 和 KY C 基因印射，它旋转白色和黄分别地包。DNA 从单个蛹被提取并且为简单顺序重复(SSR ) 分析了标记。C 基因被发现被连接到七个 SSR 标记。从女异质接合的回交(BC <SUB>1</SUB> F ) 的所有黄茧个人在连接组 12 上为 SSR 标记显示出异质接合的侧面，而有轻黄茧的个人显示出紧张 C108 的同型结合的侧面。用相互的异质接合的男回交(BC <SUB>1</SUB> M ) ，我们构造了 36.4 厘米的一张连接地图， C 基因在 13.9 厘米的距离在远侧的结束，和最靠近的 SSR 标记定位了。展开更多
基金the National Natural Science Foundation of China(No.11475261)partially supported by the National Key Project of Research and Development of China(No.2016YFC0904600).
文摘The aim of this study was to design a cage-like radiotherapy system(CRTS)to further promote the clinical application of noncoplanar radiotherapy.The CRTS comprises two stands,two O-rings,several arc girders,an X-ray head,an imaging subsystem,and a treatment couch.The X-ray head rotates with O-rings around the patient’s body and slides along the arc girder.Compared with the C-arm linear accelerator(C-Linac),the clinically available spatial irradiation angle ranges(SIARs)of the CRTS for the head,chest,and abdomen were 33%,63.6%,and 62.6%larger,respectively.Moreover,according to a preliminary planning comparison based on the dose distribution simulation method,the CRTS achieved much better protection of normal tissue than the C-Linac.Furthermore,the CRTS enabled accurate noncoplanar irradiation without movement of the body being irradiated,allowed automatic control of the movements of different parts without risk of collisions,and provided continuous radiation over an angle that considerably exceeded a full turn.These advantages make CRTS very promising for noncoplanar radiotherapy.
文摘To investigate the effects of individualised treatment with peginterferon alpha-2a(40 kD)plus ribavirin in Chinese patients with CHC.Methods Total of 297 consecutive Chinese patients were enrolled,including 250 nave cases and 47 cases who were previously treated.Treatment duration was determined according to viral genotypes,prior treatment history and viral responses at week 4,12 and 24.Results Totally,235 patients(79.1%)completed treatment and 186(87.3%)achieved SVR.And 219 out of 289(75.8%)patients achieved HCV RNA negative at week 4(RVR)and 259 of 276(93.8%)at week 12.Among the 164 patients with RVR who completed follow-up,158(96.3%)achieved SVR.Patients with RVR had lower baseline viral loads than patients without RVR(P=0.034).The positive predictive value(PPV)of RVR for SVR was 90.7%(OR 2.10 vs.non-RVR,95%CI:0.50-8.7).Similar outcomes were observed among patients with HCV undetectable at week 12.Conclusions Viral suppression by week 4 is associated with a high rate of treatment success in treatment nave and experienced patients receiving individualized CHC therapy.
基金supported by Scientific Research Projects of Beijing Ditan HospitalCapital Medical University+1 种基金Projects from Beijing Municipal Science and Technology Commission (D171100003117005)Digestive Medical Coordinated Development Center of Beijing Hospitals Authority (XXZ0402)。
文摘Background: Recent studies reported that patients with coronavirus disease-2019(COVID-19) might have liver injury. However, few data on the combined analysis and change patterns of alanine aminotransferase(ALT), aspartate aminotransferase(AST) and total bilirubin(TBil) have been shown.Methods: This is a single-center retrospective study. A total of 105 adult patients hospitalized for confirmed COVID-19 in Beijing Ditan Hospital between January 12, and March 17, 2020 were included, and divided into mild group(n=79) and severe group(n=26). We compared liver functional test results between the two groups. Category of ALT change during the disease course was also examined.Results: 56.2%(59/105) of the patients had unnormal ALT, AST, or total TBil throughout the course of the disease, but in 91.4%(96/105) cases the level of ALT, AST or TBil ≤3 fold of the upper limit of normal reference range(ULN). The overall distribution of ALT, AST, and TBil were all significantly difference between mild and severe group(P<0.05). The percentage of the patients with elevated both ALT and AST was 12.7%(10/79) in mild cases vs. 46.2%(12/26) in severe cases(P=0.001). 34.6%(9/26) severe group patients started to have abnormal ALT after admission, and 73.3%(77/105) of all patients had normal ALT before discharge.Conclusions: Elevated liver function index is very common in patients with COVID-19 infection, and the level were less than 3×ULN, but most are reversible. The abnormality of 2 or more indexes is low in the patients with COVID-19, but it is more likely to occur in the severe group.
基金support from the China University of Petroleum(Beijing)School for Young Talent Startup Fund(No.ZX20190183).
文摘Fracture propagation is affected by multi-metal-veins formed by geological diagenesis in shale during the hydraulic fracturing.However,the influence of multi-metal-veins on fractures propagation remains unclear.To solve the problem,based on the semi-circle bending(SCB)test and the extended finite element(XFEM)theory,the interaction between multi-metal-veins and fractures is investigated.The experimental results reveal that the fractures usually deflect at the upper or lower interfaces between metal veins and rocks(e.g.the specimen S-2),which is different from the propagation behavior of fractures in calcite veins.Meanwhile,the fracture toughness of the specimen S-1 is 24.40%higher than that of the specimen S-2,indicating that the increasing of total thickness of multiple metal veins in-creases the resistance to the fracture vertical propagation.The simulation results show that the increasing of the number,total thickness of veins,the modulus difference between veins and rock,the approach angle and the notch angle all increase the resistance of the fracture passing through metal veins.The maximum deviation distance(Dmax)of the fracture decreases with the number of veins,while thickness combination types of metal veins do not affect Dmax.The reduction of the notch angle leads to the more tortuous fracture propagation path.Finally,we propose a new comprehensive fracture network pattern.Fracture networks are divided into two categories,including orthogonal fracture networks and sub-orthogonal fracture networks,and then divided into six sub-categories further.The research results will provide reference for hydraulic fracturing of shale reservoirs containing multi-metal-veins.
基金supported by the National SKA Program of China No.2020SKA0120100the National Natural Science Foundation of China(NSFC,Grant Nos.11963002,11703047,11773041,U2031119,12173052,12003047 and 12173053)+7 种基金the fostering project of Guizhou University with No.201911Cultivation Project for FAST Scientific Payoff and Research Achievement of CAMS-CASsupported by the Specialized Research Fund for State Key Laboratoriessupported by the CAS“Light of West China”Programthe Youth Innovation Promotion Association of CAS(id 2023064)supported by the Youth Innovation Promotion Association of CAS(id.2018075 and Y2022027)supported by Guizhou Provincial Basic Research Program(Natural Science)(ZK[2023]039)Key Technology R&D Program([2023]352)。
文摘Up to 2022 November,267 pulsars had been discovered in 36 globular clusters(GCs).In this paper,we present our studies on the distribution of GC pulsar parameters and the detection efficiency.The power law relation between average dispersion measure(■)and dispersion measure difference(ΔDM)of known pulsars in GCs is lgΔDM∝1.52lg■.The sensitivity could be the key to finding more pulsars.As a result,several years after the construction of a large radio telescope facility,the number of known GC pulsars will likely be increased accordingly.We suggest that currently GCs in the southern hemisphere could have higher possibilities for finding new pulsars.
文摘BACKGROUND Ultrasound is a vital tool for the diagnosis and management of colorectal cancer(CRC).Contrast-enhanced ultrasound(CEUS)is a non-invasive,safe,and cost-effective method for evaluating tumour blood vessels,that play a crucial role in tumour growth and progression.AIM To explore CEUS’s role in the quantitative evaluation of CRC blood vessels and their correlation with angiogenesis markers and prognosis.METHODS This study prospectively enrolled 100 patients with CRC confirmed by histo-pathology.All patients received preoperative CEUS examinations.Quantitative parameters,such as peak intensity(PI),time to peak(TTP),and area under the curve(AUC),were derived from time-intensity curve(TIC)analysis.Tumour tissue samples were obtained during surgery and examined immunohistochem-ically to assess the expression of angiogenesis markers,including vascular endo-thelial growth factor(VEGF)and microvessel density(MVD).The correlation between CEUS parameters,angiogenesis markers,and clinicopathological features was evaluated using appropriate statistical tests.RESULTS Quantitative CEUS parameters(PI,TTP,and AUC)showed significant correlations with VEGF expression(P<0.001)and MVD(P<0.001),indicating a strong link between tumour blood vessels and angiogenesis.Increased PI,reduced TTP,and expanded AUC values were significantly related to higher tumour stage(P<0.001),lymph node metastasis(P<0.001),and distant metastasis(P<0.001).Furthermore,these parameters were recognized as independent predictors of overall survival and disease-free survival in multivariate analysis(P<0.001).CONCLUSION CEUS has a high potential in guiding treatment planning and predicting patient outcomes.However,more com-prehensive,multicentre studies are required to validate the clinical utility of CEUS in CRC management.
文摘BACKGROUND: The availability of novel direct-acting antivirals(DAAs) represents a new era of curative hepatitis C virus(HCV) treatment, with over 95% of patients infected with HCV genotype 1 achieving sustained virological response(SVR). Nevertheless, the majority of patients globally are unable to access these treatments because of cost and infrastructure constraints and, thus, remain untreated and uncured.DATA SOURCE: Relevant articles of peginterferon(Peg IFN)-based treatments in HCV and sofosbuvir-based treatments, simeprevir, daclatasvir/asunaprevir, ritonavir-boosted paritaprevir/ombitasvir/dasabuvir, and grazoprevir/elbasvir, were searched in Pub Med database, including general population and special population.RESULTS: Peg IFN in combination with ribavirin remains an important and relevant option for some patients, achieving SVR rates of up to 79% in genotype 1 and 89% in genotype 2 or 3 infections, which increases for patients with favorable IL28 B genotypes. Triple therapy of DAA plus Peg IFN/ribavirin is effective in treating difficult-to-cure patients infected with HCV genotype 3 or with resistance-associated variants. Owing to its long history in HCV management, the efficacy, tolerability and long-term outcomes associated with Peg IFN alfa-2a are well established and have been validated in largescale studies and in clinical practice for many populations. Furthermore, emerging data show that IFN-induced SVR is associated with lower incidences of hepatocellular carcinoma compared with DAAs. On the contrary, novel DAAs have yet to be studied in special populations, and long-term outcomes, particularly tumor development and recurrence in patients with cirrhosis and/or hepatocellular carcinoma, and reactivation of HBV in dually infected patients, are still unclear.CONCLUSION: In this interferon-free era, Peg IFN-based regimens remain a safe and effective option for selected HCV patients.
文摘AIM: To examine the association between interferon(IFN) therapy and loss of hepatitis B surface antigen(HBs Ag) in inactive HBs Ag carriers. METHODS: This was a retrospective cohort study in inactive HBs Ag carriers, who were treatment-naive, with a serum HBs Ag level < 100 IU/m L and an undetectable hepatitis B virus(HBV) DNA level(< 100 IU/m L). All the 20 treated patients received subcutaneous PEG-IFN alfa-2a 180 μg/wk for 72 wk and were then followed for 24 wk. There were 40 untreated controls matched with 96 wk of observation. Serum HBs Ag, HBV DNA, and alanine aminotransferases were monitored every 3 mo in the treatment group and every 3-6 mo in the control group. RESULTS: Thirteen(65.0%) of 20 treated patients achieved HBs Ag loss, 12 of whom achieved HBs Ag seroconversion. Mean HBs Ag level in treated patients decreased to 6.69 ± 13.04 IU/m L after 24 wk of treatment from a baseline level of 26.22 ± 33.00 IU/m L. Serum HBV DNA level remained undetectable(< 100 IU/m L) in all treated patients during the study. HBs Ag level of the control group decreased from 25.72 ± 25.58 IU/m L at baseline to 17.11 ± 21.62 IU/m L at week 96(P = 0.108). In the control group, no patient experienced HBs Ag loss/seroconversion, and two(5.0%) developed HBV reactivation.CONCLUSION: IFN treatment results in HBs Ag loss and seroconversion in a considerable proportion of inactive HBs Ag carriers with low HBs Ag concentrations.
基金the National Natural Science Foundation of China fund (Project number: 52174045 and No. 52104011)Research Foundation of China University of Petroleum-Beijing at Karamay (No. XQZX20210001)PetroChina Innovation Foundation (2020D50070207)。
文摘Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness of reservoir stimulation. Temporary plugging and diverting fracturing(TPDF) is considered to be a potential uniform-stimulation method for creating multiple fractures simultaneously in the oilfield. However, the multi-fracture propagation morphology during TPDF is not clear now. The purpose of this study is to quantitatively investigate the multi-fracture propagation morphology during TPDF through true tri-axial fracturing experiments and CT scanning. Critical parameters such as fracture spacing, number of perforation clusters, the viscosity of fracturing fluid, and the in-situ stress have been investigated. The fracture geometry before and after diversion have been quantitively analyzed based on the two-dimensional CT slices and three-dimensional reconstruction method. The main conclusions are as follows:(1) When injecting the high viscosity fluid or perforating at the location with low in-situ stress, multiple hydraulic fractures would simultaneously propagate. Otherwise, only one hydraulic fracture was created during the initial fracturing stage(IFS) for most tests.(2) The perforation cluster effectiveness(PCE) has increased from 26.62% during the IFS to 88.86% after using diverters.(3) The diverted fracture volume has no apparent correlation with the pressure peak and peak frequency during the diversion fracturing stage(DFS) but is positively correlated with water-work.(4) Four types of plugging behavior in shale could be controlled by adjusting the diverter recipe and diverter injection time, and the plugging behavior includes plugging the natural fracture in the wellbore, plugging the previous hydraulic fractures, plugging the fracture tip and plugging the bedding.
基金supported by the Major New Drug Creation Program from National Science and Technology Major Project of China(2014ZX09303305).
文摘Background Uncertainty remains regarding the association between body mass index(BMI)and the risk of bleeding in patients with non-valvular atrial fibrillation(NVAF).We aimed to investigate the association between BMI and the risk of bleeding in elderly NVAF patients taking dabigatran.Methods A total of 509 elderly NVAF patients,who were being treated at twelve centers in China from February 2015 to December 2017 and taking dabigatran,were analyzed.The exposure and outcome variables were BMI at baseline and bleeding events within the subsequent six months,respectively.Cox proportional hazards regression analysis was used to evaluate the association between BMI and the risk of bleeding.Moreover,the Cox proportional hazards regression with cubic spline functions and smooth curve fitting was conducted.Results During the six-month follow-up,50 participants experienced bleeding.Every 1 kg/m^2 increase in BMI was associated with a 12%increased risk of bleeding(P=0.021).Compared to those with BMI values in Tertile 1(<22.5 kg/m^2),the adjusted hazard ratio(HR)of bleeding for participants in Tertile 2(22.5–25.3 kg/m^2)and Tertile 3(>25.3 kg/m^2)were 2.71(95%CI:1.02–7.17)and 3.5(95%CI:1.21–8.70),respectively.The Ptrend-value was significant in all models.The adjusted smooth curve showed a linear association between BMI and bleeding.None of the stratified variables showed significant effect modification on the association between BMI and bleeding(Pinteraction>0.05).Conclusions BMI was significantly and positively associated with the risk of bleeding in elderly NVAF patients treated with dabigatran.
基金The project was supported by the Grants (2003BA712A08-02 and 2004BA718B03) from the Chinese Ministry of Science and Technology.
文摘Saliva and blood were collected from two patients who had not received post exposure prophylaxis in the cities of Wenzhou and Xinning respectively. Both patients were confirmed as positive for rabies by detection of rabies virus specific nucleoprotein antibodies in the sera by Western Blot. However, rabies virus specific RNA was only identified in the saliva collected from the patient in Wenzhou. Furthermore, the isolate Zhejiang Wz0 (H) was obtained by inoculating one-day-old suckling mice. Both nucleoprotein (N) and glycoprotein (G) genes from the isolate were amplified by RT-PCR and sequenced. Phylogenetic analysis indicated that the isolate belonged to classic rabies virus, and shared a higher homology with the street viruses from dogs in the main endemic areas in China and the street virus from dogs in Indonesia than with other known strains. Further comparison of the deduced amino acid sequences between the isolate and the vaccine strains used in China showed that the virus had a higher level of homology with the vaccine strain CTN than with the other vaccine strains (3aG, PV, PM and ERA). In particular, amino acid residues substitutions located in antigenic site Ⅲ in the G protein, which could react with the neutralizing antibodies, were observed. These results suggested that the virus belonged to the classic rabies virus, and both N and G genes diverged from the current vaccine strains used in China at either the nucleotide or the amino acid level.
基金financially supported by the National Natural Science Foundation of China(No.52174045,No.52104011)Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01B77)。
文摘Intra-stage multi-cluster temporary plugging and diverting fracturing(ITPF)is one of the fastest-growing techniques to obtain uniform reservoir stimulation in shale gas reservoirs.However,propagation geometries of multiple fractures during ITPF are not clear due that the existing numerical models cannot capture the effects of perforation plugging.In this paper,a new three-dimensional FEM based on CZM was developed to investigate multiple planar fracture propagation considering perforation plugging during ITPF.Meanwhile,the fluid pipe element and its subroutine were first developed to realize the flux partitioning before or after perforation plugging.The results showed that the perforation plugging changed the original distribution of the number of perforations in each fracture,thus changing the flux partitioning after perforation plugging,which could eliminate the effect of stress interference between multiple fractures and promote a uniform fluid distribution.The standard deviation of fluid distribution in the perforation plugging case was only 8.48%of that in the non-diversion case.Furthermore,critical plugging parameters have been investigated quantitatively.Specifically,injecting more diverters will create a higher fluid pressure rise in the wellbore,which will increase the risk of wellbore integrity.Comprehensively considering pressure rise and fluid distribution,the number of diverters should be 50%of the total number of perforations(N_(pt)),whose standard deviation of fluid distribution of multiple fractures was lower than those in the cases of injecting 10%N_(pt),30%N_(pt)and 70%N_(pt).The diverters should be injected at an appropriate timing,i.e.40%or 50%of the total fracturing time(tft),whose standard deviation of the fluid distribution was only about 20%of standard deviations in the cases of injecting at20%tftor 70%tft.A single injection with all diverters can maintain high bottom-hole pressure for a longer period and promote a more uniform fluid distribution.The standard deviation of the fluid distribution in the case of a single injection was 43.62%-55.41%of the other cases with multiple injection times.This study provides a meaningful perspective and some optimal plugging parameters on the field design during IPTF.
基金the National Natural Science Foundation of China(Grant No.11673039)the Open Project Program of the Key Laboratory of FAST,NAOC,Chinese Academy of Sciencesthe Key Laboratory of Radio Astronomy,Chinese Academy of Sciences。
文摘This paper presents a new measurement system based on integration method that can provide all-weather dependability and higher precision for the measurement of FAST's feed support system.The measurement system consists of three types of measuring equipments,and a processing software with the core data fusion algorithm.The Strapdown Inertial Navigation System(SINS)can autonomously measure the position,speed and attitude of the carrier.Its own shortcoming is that the measurement data diverge rapidly over time.SINS must combine the Global Positioning System(GPS)and the Total Station(TS)to obtain high-precision measurement data.The Kalman filtering algorithm is adopted for the integration measurement system,which is an optimal algorithm to estimate the measurement errors.A series of tests are carried out to evaluate the performance.For the feed cabin,the maximum RMS of the position is 14.56 mm,the maximum RMS of the attitude is 0.095,these values are less than 15 mm and 0.1°as the precision for measuring the feed cabin.For the Stewart manipulator,the maximum RMS of the position is 2.99 mm,the maximum RMS of the attitude is 0.093°,these values are less than 3 mm and 0.1°as the precision for measuring the Stewart manipulator.As a result,the new measurement meets the requirement of measurement precision for FAST's feed support system.
基金Acknowledgments This project was supported by the National Basic Research （973） Program （grant no. 2005CB121000）, Natural Science Foundation of Jiangsu Province （grant no. BK2006508）, Hi-tech Research and Development Program （863） of China （2006AA10A119）.
文摘蚕 Bombyx 粗腐殖质 i 的茧的黄颜色被三基因控制， Y (黄 haemolymph ) ，我(黄禁止者) 并且 C (外部层的黄茧) 它位于连接分别地组织 2， 9 和 12。利用交叉在上的缺乏在女性，相互的 backcrossed F <SUB>1</SUB>(BC <SUB>1</SUB>) 子孙被用于连接分析并且用蚕紧张 C108 和 KY C 基因印射，它旋转白色和黄分别地包。DNA 从单个蛹被提取并且为简单顺序重复(SSR ) 分析了标记。C 基因被发现被连接到七个 SSR 标记。从女异质接合的回交(BC <SUB>1</SUB> F ) 的所有黄茧个人在连接组 12 上为 SSR 标记显示出异质接合的侧面，而有轻黄茧的个人显示出紧张 C108 的同型结合的侧面。用相互的异质接合的男回交(BC <SUB>1</SUB> M ) ，我们构造了 36.4 厘米的一张连接地图， C 基因在 13.9 厘米的距离在远侧的结束，和最靠近的 SSR 标记定位了。
基金The work was supported by grants from the Basic and Clinical Fund of Capital Medical University （No. 17JL88） and National Natural Science Foundation of China （No. 81071344）.
