Numerical study of hydraulic fracturing in the sectorial well-factory considering well interference and stress shadowing

In the Changqing Oilfield in northwest China, when traditional petroleum exploitation encounters forestry reserves or water source protection areas, sectorial well-factory design is proposed. The most distinct feature of a sectorial well-factory is the deviation of the well from the minimum horizontal principal stress, resulting in hydraulic fracture deflection after the initiation, along with possible well interference (i.e., fracture hit) and fracture coalescence in the oblique wells. Four indexes describing well deflection are then proposed according to fracture morphology. Several fracturing designs, including stage arrangement, fracturing sequences, and fracturing techniques are applied to study the feasibility of the sectorial well-factory design. The results show that the “gradual” or “sparse” stage arrangement, large injection rate, and simultaneous multifracture treatment can help to optimize the fracture morphology and stimulation design. However, the subsequent stress shadowing effect usually adversely affects the fracturing of adjacent wells. With a small initial horizontal stress difference, large injection rate and staggered stage arrangement can achieve ideal stimulation performance. Our results can provide a guidance for optimizing stimulation design in unconventional well-factory while taking into account environmental protection.

ROC曲线和Logistic回归评估PAF联合NFATc1对冠心病的诊断价值

目的探讨ROC曲线和Logistic回归评估血小板活化因子(PAF)和活化T淋巴细胞核因子c1(NAFTc1)对冠状动脉粥样硬化性心脏病(冠心病)的诊断价值。方法选取2014年1月-2016年1月该院就诊的188例疑似冠心病患者为研究对象,根据冠状动脉造影结果分为对照组和冠心病组,其中对照组56例,冠心病组132例。采用ELISA法检测两组患者血清PAF、NAFTc1浓度,采用Logistic回归方程和ROC曲线判定单项检测和联合检测在冠心病诊断中的价值。结果对照组和冠心病组血清PAF浓度分别为(8.95±5.74)和(18.13±4.72)ng/ml,NAFTc1浓度分别为(22.78±3.15)和(30.58±5.24)pg/ml,两组比较差异有统计学意义(P <0.05)。以PAF、NAFTc1 2个单因素为自变量,进行二项分类Logistic回归分析,得到Logistic回归模型:Logit(P)=-8.463+0.417PAF+0.098NAFTc1,该模型诊断准确率为85.64%。PAF、NAFTc1、Logistic回归模型联合检测的曲线下面积分别为0.806、0.815及0.900,差异有统计学意义(P <0.05),Logistic回归模型联合检测的95%CI(0.838,0.962)。PAF检测阈值为9.75 ng/ml,NAFTc1检测阈值为23.95 pg/ml,Logistic回归模型联合检测敏感性为0.86,特异性为0.71。结论 PAF联合NFATc1检测效果优于单项检测,可用于冠心病筛查,具有较高的诊断价值。

Precipitates and corrosion resistance of an Al-Zn-Mg-Cu-Zr plate with different percentage reduction per passes

7055 aluminum alloy plates with the same size were rolled by two processes： small percentage reduction per pass （PRPP） and large percentage reduction per pass, respectively. Meanwhile, the effect of PRPP on the precipitates and corrosion resistance of 7055 aluminum alloy plate was investigated. The mechanisms were analyzed and discussed by optical microscopy （OM）, transmission electron microscopy （TEM）, high-resolution transmission electron microscopy （HRTEM） and electron back-scattered diffraction （EBSD） technique. Large PRPP can improve the corrosion resistance. For the plate rolled by small PRPP, the main precipitate is guinier-preston （GP） zone and continuous grain boundary precipitates （GBPs）, while, for the plate rolled by large PRPP, the main precipitates are the GP zone and η precipitate, and the GBPs are discontinuous.

Fundamentals and photocatalytic hydrogen evolution applications of quaternary chalcogenide semiconductor:Cu_(2)ZnSnS_(4)

Inexpensive,safe,and efficient conversion of solar energy to hydrogen from water splitting requires the development of effective and durable photocatalysts.Cu_(2)ZnSnS_(4)(CZTS),the emerging quaternary chalcogenide material for solar energy conversion,possesses many advantages,such as narrow direct band gap(1.5 eV),nontoxic,earth-abundance,and low melting point.Currently,CZTS-based photocatalysts have been extensively investigated for their application as an active photocatalyst in hydrogen evolution from water splitting,while the performance is still highly needed to be improved for the practical applications.In this review,first,the crystal and band structure properties of CZTS are briefly introduced,and afterward,the basic principle of photocatalytic hydrogen evolution from water splitting is discussed.Subsequently,the performance and status of bare CZTS,the combination of CZTS and co-catalysts,and CZTSbased heterojunction photocatalysts for hydrogen evolution are reviewed and discussed in detail.Finally,the issues and challenges currently encountered in the application of CZTS and their possible solutions for developing advanced CZTS photocatalysts are provided.

Efficacy and safety of a parylene-coated occluder for atrial septal defect:a prospective,multi-center,randomized controlled clinical trial

Background:Nitinol-containing devices are widely used in clinical practice.However,there are concerns about nickel release after nitinol-containing device implantation.This study aimed to compare the efficacy and safety of a parylene-coated occluder vs.a traditional nitinol-containing device for atrial septal defect(ASD).Methods:One-hundred-and-eight patients with ASD were prospectively enrolled and randomly assigned to either the trial group to receive a parylene-coated occluder(n=54)or the control group to receive a traditional occluder(n=54).The plugging success rate at 6 months after device implantation and the pre-and post-implantation serum nickel levels were compared between the two groups.A non-inferiority design was used to prove that the therapeutic effect of the parylene-coated device was non-inferior to that of the traditional device.The Cochran–Mantel–Haenszel chi-squared test with adjustment for central effects was used for the comparison between groups.Results:At 6 months after implantation,successful ASD closure was achieved in 52 of 53 patients(98.11%)in both the trial and control groups(95%confidence interval(CI):[4.90,5.16])based on per-protocol set analysis.The absolute value of the lower limit of the 95%CI was 4.90%,which was less than the specified non-inferiority margin of 8%.No deaths or severe complications occurred during 6 months of follow-up.The serum nickel levels were significantly increased at 2 weeks and reached the maximum value at 1 month after implantation in the control group(P<0.05 vs.baseline).In the trial group,there was no significant difference in the serum nickel level before vs.after device implantation(P>0.05).Conclusions:The efficacy of a parylene-coated ASD occluder is non-inferior to that of a traditional uncoated ASD occluder.The parylene-coated occluder prevents nickel release after device implantation and may be an alternative for ASD,especially in patients with a nickel allergy.

Hydrogen agronomy:research progress and prospects

Agriculture is the foundation of social development.Under the pressure of population growth,natural disasters,environmental pollution,climate change,and food safety,the interdisciplinary"new agriculture"is becoming an important trend of modern agriculture.In fact,new agriculture is not only the foundation of great health and new energy sources,but is also the cornerstone of national food security,energy security,and biosafety.Hydrogen agronomy focuses mainly on the mechanism of hydrogen gas(H2)biology effects in agriculture,and provides a theoretical foundation for the practice of hydrogen agriculture,a component of the new agriculture.Previous research on the biological effects of H2 focused chiefly on medicine.The mechanism of selective antioxidant is the main theoretical basis of hydrogen medicine.Subsequent experiments have demonstrated that H2 can regulate the growth and development of plant crops,edible fungus,and livestock,and enhance the tolerance of these agriculturally important organisms against abiotic and biotic stresses.Even more importantly,H2 can regulate the growth and development of crops by changing the soil microbial community composition and structure.Use of H2 can also improve the nutritional value and postharvest quality of agricultural products.Researchers have also shown that the biological functions of molecular hydrogen are mediated by modulating reactive oxygen species(ROS),nitric oxide(NO),and carbon monoxide(CO)signaling cascades in plants and microbes.This review summarizes and clarifies the history of hydrogen agronomy and describes recent progress in the field.We also argue that emerging hydrogen agriculture will be an important direction in the new agriculture.Further,we discuss several scientific problems in hydrogen agronomy,and suggest that the future of hydrogen agronomy depends on contributions by multiple disciplines.Important future research directions of hydrogen agronomy include hydrogen agriculture in special environments,such as islands,reefs,aircraft,and outer space.

Is intestinal metaplasia the point of no return in the progression of gastric carcinogenesis?

Gastric cancer(GC)is one of the most common malignant tumors worldwide.In China,GC is the second most common malignant tumor,and it is the second leading cause of cancer mortality.[1]Correa model showed that the development of intestinal-type GC was a consecutive cancerous process including normal gastric mucosa,non-atrophic gastritis,atrophic gastritis(AG),intestinal metaplasia(IM),dysplasia and intestinal-type GC in sequence.[2]Epithelium-resembling intestinal morphology replaced gastric mucosa which was defined as IM.[3]Among these precancerous conditions,IM was demonstrated to be a vital risk factor for GC,especially incomplete IM and extensive IM.[4,5].

Dynamic recrystallization behavior and finite element analysis of a low-alloy high-strength steel

The axial single-pass high temperature compression test of a hot-rolled extra-large heavy H-beam steel continuous casting billet (Q420 steel) under different deformation conditions through the Gleeble-1500D thermomechanical simulator was carried out. The modified Johnson–Cook model and the Arrhenius model based on strain-compensated of Q420 steel were established. The latter can more accurately reflect the flow behavior of Q420 steel. For the simulation of thermal compression, dynamic recrystallization (DRX) correlation models were developed and imported into DEFORM-3D software. According to simulation results, high temperatures and low strain rates are conducive to DRX. Due to the uneven distribution of equivalent strain and temperature in different parts of the same section, DRX volume fraction and grain size are unevenly distributed. At the center, the DRX volume fraction is the largest and the grain size is the smallest. The upper and lower edges are vice versa, and the left and right edges are centered. Optical microscopy and electron backscatter diffraction characterization methods were used to study the hot compression microstructure under different deformation conditions. As the deformation amount increases, complete DRX is gradually reached. The original austenite grain gradually becomes smaller. Local average misorientation decreases with the progression of DRX but increases with the amount of deformation after completion of DRX. As the temperature increases and the rate decreases, low angle grain boundaries and medium angle grain boundaries gradually decrease, and high angle grain boundaries gradually increase, indicating that dislocation decreases gradually, DRX grains increase gradually, and martensitic multilayer structure is obvious. As austenite grain size increases, the length of martensite lath increases, and the number of martensite blocks decreases.