Sensitivity of seismic attenuation and dispersion to dynamic elastic interactions of connected fractures: Quasi-static finite element modeling study

Prediction of seismic attenuation and dispersion that are inherently sensitive to hydraulic and elastic properties of the medium of interest in the presence of mesoscopic fractures and pores,is of great interest in the characterization of fractured formations.This has been very difficult,however,considering that stress interactions between fractures and pores,related to their spatial distributions,tend to play a crucial role on affecting overall dynamic elastic properties that are largely unexplored.We thus choose to quantitatively investigate frequency-dependent P-wave characteristics in fractured porous rocks at the scale of a representative sample using a numerical scale-up procedure via performing finite element modelling.Based on 2-D numerical quasi-static experiments,effects of fracture and fluid properties on energy dissipation in response to wave-induced fluid flow at the mesoscopic scale are quantified via solving Biot's equations of consolidation.We show that numerical results are sensitive to some key characteristics of probed synthetic rocks containing unconnected and connected fractures,demonstrating that connectivity,aperture and inclination of fractures as well as fracture infills exhibit strong impacts on the two manifestations of WIFF mechanisms in the connected scenario,and on resulting total wave attenuation and phase velocity.This,in turn,illustrates the importance of these two WIFF mechanisms in fractured rocks and thus,a deeper understanding of them may eventually allow for a better characterization of fracture systems using seismic methods.Moreover,this presented work combines rock physics predictions with seismic numerical simulations in frequency domain to illustrate the sensitivity of seismic signatures on the monitoring of an idealized geologic CO_(2) sequestration in fractured reservoirs.The simulation demonstrates that these two WIFF mechanisms can strongly modify seismic records and hence,indicating that incorporating the two energy dissipation mechanisms in the geophysical interpretation can potentially improving the monitoring and surveying of fluid variations in fractured formations.

六味地黄汤对血液透析患者肝肾阴虚型血小板减少症的疗效观察

目的观察六味地黄汤对血液透析患者肝肾阴虚型血小板减少症(HIT)的治疗效果。方法84例血液透析肝肾阴虚型HIT患者随机分为观察组与对照组各42例。对照组给予常规西医治疗,观察组在对照组基础上加用六味地黄汤治疗。两组疗程均为1个月。比较两组治疗前后肝肾阴虚证候积分变化及中医证候疗效;比较两组治疗前后血小板计数(Plt)、P-选择素水平、HIT抗体阳性率变化,以及两组Plt回升时间、临床疗效和不良反应发生率。结果治疗1个月后,两组肝肾阴虚证候积分均较前降低(P<0.05),且观察组低于对照组(P<0.05);观察组中医证候总有效率(97.62%)高于对照组(P<0.05)。治疗14 d后,两组Plt均较前升高,P-选择素水平、HIT抗体阳性率则较前降低(P<0.05),且观察组Plt高于对照组,P-选择素水平、HIT抗体阳性率低于对照组(P<0.05)。观察组Plt回升时间短于对照组(P<0.05),临床总有效率(95.24%)高于对照组(P<0.05);两组治疗期间不良反应发生率差异无统计学意义(P>0.05)。结论常规西医联合六味地黄汤治疗血液透析患者的肝肾阴虚型HIT,可提高临床疗效,减轻患者临床症状,提高Plt,缩短Plt回升时间,降低P-选择素水平和HIT抗体阳性率,且安全性良好,值得临床推广。

Effects of binder components and PVA modifier on bonding performance of phosphate binder for sand core-making

A type of heat-curing phosphate binder was proposed,and orthogonal experiments based on the tensile strength of sand samples determined that the optimal composition of the binder was phosphoric acid:water:aluminum hydroxide:magnesium oxide:boric acid=300:70:60:9:8.Adding 10%polyvinyl alcohol(PVA)solution during the sand mixture process can significantly improve the 24 h tensile strength of sand samples.When adding 30 g phosphate binder and 8 g 10%PVA solution,the initial tensile strength of the sample is 0.76 MPa,the room temperature tensile strength is 2.29 MPa,and the 24 h tensile strength is 1.73 MPa.The heat-curing modified phosphate sand mold has high tensile strength and low gas generation,which can meet general casting production requirements.

Preparation of a new animal glue binder for foundry use

A new casting binder was prepared based on an animal bone glue. In order to overcome the disadvantages of the animal glue agglomeration at room temperature, an alkaline decomposition process was used, with acrylic acid, ammonium persulfate, and glucose as modifiers of the animal glue to obtain a high strength of binding. In the process of alkaline decomposition, Na OH was used as the catalyst with the addition of 3, 4, 5, 6, 7, 8wt.%, respectively, into 100 g of animal glue and the alkaline decomposition temperature was set for 30, 40, 50, 60, and 70 °C, with an identical decomposition time of 30 min, in order to reduce viscosity of the animal glue and maintain a liquid state at room temperature. The added acrylic acid, ammonium persulfate and glucose were determined through an orthogonal experiment. The experimental results are as fol ows: the optimal amount of NaOH addition is 5wt.%; alkaline decomposition temperature is 50 °C; the optimal weight ratio of three kinds of modifiers to animal glue is acrylic acid : ammonium persulfate : glucose : animal glue = 30:3:15:100; the modification reaction should be performed at 75 °C with a reaction time of 90 min. With the addition of 3% binder to sand, a final tensile strength of about 3.36 MPa and surface tension value of about 25.387 m N·m^(-1) are achieved; the gas evolution at 850 °C is 19 ml·g^(-1) and the residual strength after high temperature(700 ■× 10 min) is 0 MPa. Finally, the new binder was characterized and analyzed by means of element analysis and an IR infrared spectrum.

Humidity-resistant inorganic binder for sand core making in foundry practice

The performance of sand core was improved by using the modified water glass as a binder and adding powder additives in the sand hardening process. The optimal proportion of the compound additives was determined by an orthogonal test, with a ratio of microsilica: polyvinyl alcohol solution: borax: B agent = 25: 20: 2: 1. The binder accounted for 2% of the sand by weight, and the compound additives accounted for 0.96%. The core box was heated to 175 °C, and the compressed hot air of 120 °C kept blowing for 40 s. Tensile strength was used as the main indicator to evaluate the humidity-resistance of the sand core. For the sand core, the instant tensile strength reached 0.73 MPa, the tensile strength at room temperature was 1.81 MPa, and that of sand core holding at the condition of 35 °C and 90% RH for 2 h and for 4 h reached 1.61 MPa and 1.19 MPa, respectively. The gas evolution was 7.5 mL·g-1 at 850 °C for 3 min. The residual tensile strength was 0 MPa at 750 °C for 5 min. Fourier-transform infrared spectroscopy analysis showed that the humidity-resistance of the core was greatly improved by the powder additives.

Correlation between resilience and social support and anxiety in obstetric nurses

Objective: The aim of this study was to explore the correlation between psychological resilience and social support and anxiety in obstetric nurses and to provide theoretical basis for improving the mental health of obstetric nurses.Methods: In this study, 190 obstetric nurses were included, using the general information questionnaire and The Connor-Davidson Resilience Scale(CD-RISC), Social Support Rating Scale, and survey of Self-evaluation of Anxiety Scale.Results: There are differences in the type of work and the score of psychological resilience(P<0.05), obstetric nurses’ resilience score was 65.58±10.65; self-rating anxiety score of obstetric nurses was 36.89±6.87; and social support score of obstetric nurses was44.3717.86. The psychological elasticity score and anxiety were negatively related(P<0.01), whereas the resilience score and total score of social support were positively related(P<0.01).Conclusions: Obstetric nurses have many responsibilities and stress. Nursing managers should focus on obstetric nurses’ mental health, lighten the obstetric nurses’ anxiety, and thus improve their mental flexibility and optimize the quality of nursing service better,with more passion into work.

Free-radical evolution and decay in cross-linked polytetrafluoroethylene irradiated by gamma-rays

Electron spin resonance techniques were employed to investigate the effects of the absorbed dose and post-irradiation conditions on the evolution and decay of free-radicals in cross-linked polytetrafluoroethylene(XPTFE),induced byγ-ray radiation.Chain-end free-radicals,chain alkyl free-radicals,and tertiary alkyl free-radicals were detected when XPTFE was irradiated under Ar atmosphere.The corresponding peroxy free-radicals were formed upon exposure of irradiated XPTFE to air;the freeradicals concentration first increased linearly with increasing absorbed dose and then gradually saturated.The free-radicals yield under air atmosphere was greater than that under Ar,and the peroxy free-radicals were preserved for a relatively long time when irradiated XPTFE was stored under air atmosphere.The chain alkyl free-radicals may be converted to chain end free-radicals byβ-scission,while chain end free-radicals are more sensitive to oxygen than chain alkyl free-radicals.When the annealing temperature was raised above the a-transition temperature of XPTFE,the decay of the free-radicals was greatly affected and accelerated by the motion of the molecules over the long range.

Modification of inorganic binder used for sand core-making in foundry practice

With modified water glass as binder and the introduction of micro silicon powders into the coremaking process,an improvement was made to the tensile strength and collapsibility of the sand core.The potassium hydroxide,sodium hexametaphosphate and white sugar were applied as the modifiers of water glass.The optimum proportion of the modifiers was determined through the combination of single factor test and orthogonal test.The optimum proportion of water glass,potassium hydroxide,sodium hexametaphosphate and white sugar is 1000:40:5:5(wt.).In terms of weight,modified binder and micro silicon powders accounted for 2%and 0.6%of sand,respectively.The sand core was hardened by going through a warm core box process,in which the temperature of core box was 150°C,and the compressed hot air was blown at 120°C for 40 s under a pressure of 0.2 MPa.As for the sand core bonded with modified water glass,the tensile strength is 2.46 MPa at room temperature(σ0)and 2.49 MPa at 25°C and 40%RH for 24 h(σ24),which are 2 times more than that with unmodified binder.The bonded strengths of sand core are increased as a result of the reaction between-OH groups from addition of potassium hydroxide and SiO2 particles widely distributed in the sand core.Comparing with the sand core bonded with unmodified water glass,the high temperature residual tensile strength(σr)of sand core bonded with modified water glass under 600°C for 5 min,is sharply reduced from 0.20 MPa to 0.01 MPa.By the comparison with unmodified water glass,the dynamic viscosity of the modified water glass and the flowability of molding sand using modified water glass are increased from 74 mPa·s and 2.15 g to 80 mPa·s and 2.21 g,respectively.As revealed by FT-IR analysis,new groups including PO3-,PO43-,and Si-O-C appear in the molecular structure of modified water glass,which are beneficial to the collapsibility of sand core.

Oxide-aperture-dependent output characteristics of circularly symmetric VCSEL structure

The influence ot oxidation aperture on the output characteristics ot the circularly symmetric vertical-cavity-surtaceemitting laser(VCSEL) structure is investigated.To do so,VCSELs with different oxide aperture sizes are simulated by the finite-difference time-domain(FDTD) method.The relationships among the field distribution of mode superposition,mode wavelength,output spectra,and far-field divergence with different oxide apertures are obtained.Further,VCSELs respectively with oxide aperture sizes of 2.7 μm,4.4 μm,5.9 μm,7 μm,8 μm,9 μm,and 18.7 μm are fabricated and characterized.The maximum output power increases from 2.4 mW to 5.7 mW with oxide aperture increasing from 5.9 μm to 9 μm.Meanwhile,the wavelength tuning rate decreases from 0.93 nm/mA to 0.375 nm/mA when the oxide aperture increases from 2.7 μm to 9 μm.The thermal resistance decreases from 2.815℃/mW to 1.015℃/mW when the oxide aperture increases from 4.4 μm to 18.7μm.It is demonstrated theoretically and experimentally that the wavelength spacing between adjacent modes increases with the augment of the injection current and the spacing becomes smaller with the oxide aperture increasing.Thus it can be reported that the aperture size can effectively reduce the mode overlaying but at the cost of the power decreasing and the wavelength tuning rate and thermal resistance increasing.

Effect of cardiac output-guided hemodynamic management on acute lung injury in pediatric living donor liver transplantation

BACKGROUND Acute lung injury(ALI)after liver transplantation(LT)may lead to acute respiratory distress syndrome,which is associated with adverse postoperative outcomes,such as prolonged hospital stay,high morbidity,and mortality.Therefore,it is vital to maintain hemodynamic stability and optimize fluid management.However,few studies have reported cardiac output-guided(CO-G)management in pediatric LT.AIM To investigate the effect of CO-G hemodynamic management on early postoperative ALI and hemodynamic stability during pediatric living donor LT.METHODS A total of 130 pediatric patients scheduled for elective living donor LT were enrolled as study participants and were assigned to the control group(65 cases)and CO-G group(65 cases).In the CO-G group,CO was considered the target for hemodynamic management.In the control group,hemodynamic management was based on usual perioperative care guided by central venous pressure,continuous invasive arterial pressure,urinary volume,etc.The primary outcome was early postoperative ALI.Secondary outcomes included other early postoperative pulmonary complications,readmission to the intense care unit(ICU)for pulmonary complications,ICU stay,hospital stay,and in-hospital mortality.RESULTS The incidence of early postoperative ALI was 27.7%in the CO-G group,which was significantly lower than that in the control group(44.6%)(P<0.05).During the surgery,the incidence of postreperfusion syndrome was lower in the CO-G group(P<0.05).The level of intraoperative positive fluid transfusions was lower and the rate of dobutamine use before portal vein opening was higher,while the usage and dosage of epinephrine during portal vein opening and vasoactive inotropic score after portal vein opening were lower in the CO-G group(P<0.05).Compared to the control group,serum inflammatory factors(interleukin-6 and tumor necrosis factor-α),cardiac troponin I,and N-terminal pro-brain natriuretic peptide were lower in the CO-G group after the operation(P<0.05).CONCLUSION CO-G hemodynamic management in pediatric living-donor LT decreases the incidence of early postoperative ALI due to hemodynamic stability through optimized fluid management and appropriate administration of vasopressors and inotropes.

Mapping of a Wheat Resistance Gene to Yellow Mosaic Disease by Amplified Fragment Length Polymorphism and Simple Sequence Repeat Markers

Wheat （Triticum aestivum L.） yellow mosaic virus （WYMV） is transmitted by a fungal vector through soil and causes serious wheat yield losses due to yellow mosaic disease, with yellow-streaked leaves and stunted plants. In the present study, the amplified fragment length polymorphisms （AFLP） and simple sequence repeat （SSR） were used to identify the molecular linkages with the resistance gene against WYMV. Bulked segregant analysis was performed with an F2 population derived from the cross of cultivar Ningmai 9 （resistant） × cultivar Yangmai 10 （susceptible）. By screening among the resistant or susceptible parents, the F2 pools and the individuals in the F2 population with 64 combined selective AFLP primers （EcoRI/MseI） or 290 reported SSR primers, a polymorphic DNA segment （approximately 120 bp） was amplified using the primer pair E2/M5, and an SSR marker （approximately 180 bp） was located on wheat chromosome 2A using the primer Xgwm328. Analysis with MAPMAKER/Exp Version 3.0b （Whitehead institute for Biomedical Research, Cambridge, MA, USA） indicated that these two markers were dominantly associated with the resistance gene at distances of 5.4 cM or 17.6 cM, respectively. The resistance gene to WYMV derived from Ningmai 9, is temporarily named YmNM, and was mapped to wheat chromosome 2A.

Damaged male germ cells induce epididymitis in mice

Epididymitis can be caused by infectious and noninfectious etiological factors.While microbial infections are responsible for infectious epididymitis,the etiological factors contributing to noninfectious epididymitis remain to be defined.The present study demonstrated that damaged male germ cells(DMGCs)induce epididymitis in mice.Intraperitoneal injection of the alkylating agent busulfan damaged murine male germ cells.Epididymitis was observed in mice 4 weeks after the injection of busulfan and was characterized by massive macrophage infiltration.Epididymitis was coincident with an accumulation of DMGCs in the epididymis.In contrast,busulfan injection into mice lacking male germ cells did not induce epididymitis.DMGCs induced innate immune responses in epididymal epithelial cells(EECs),thereby upregulating the pro-inflammatory cytokines such as tumor necrosis factor-a(7/VF-a),interleukin-6(/L-6),and interleukin-ip(IL-ip) as well as the chemokines such as monocyte chemotactic protein-1(MCP-1),monocyte chemotactic protein-5(MCP-5),and chemokine ligand-10(CXCL10).These results suggest that male germ cell damage may induce noninfectious epididymitis through the induction of innate immune responses in EECs.These findings provide novel insights into the mechanisms underlying noninfectious epididymitis,which might aid in the diagnosis and treatment of the disease.