Comparative impact behaviours of ultra high performance concrete columns reinforced with polypropylene vs steel fibres

Polypropylene(PP) fibres have primarily used to control shrinkage cracks or mitigate explosive spalling in concrete structures exposed to fire or subjected to impact/blast loads, with limited investigations on capacity improvement. This study unveils the possibility of using PP micro-fibres to improve the impact behaviour of fibre-reinforced ultra-high-performance concrete(FRUHPC) columns. Results show that the addition of fibres significantly improves the impact behaviour of FRUHPC columns by shifting the failure mechanism from brittle shear to favourable flexural failure. The addition of steel or PP fibres affected the impact responses differently. Steel fibres considerably increased the peak impact force(up to 18%) while PP micro-fibres slightly increased the peak(3%-4%). FRUHPC significantly reduced the maximum midheight displacement by up to 30%(under 20°impact) and substantially improved the displacement recovery by up to 100%(under 20° impact). FRUHPC with steel fibres significantly improved the energy absorption while those with PP micro-fibres reduced the energy absorption, which is different from the effect of PP-macro fibre reported in the literature. The optimal fibre content for micro-PP fibres is 1% due to its minimal fibre usage and low peak and residual displacement. This study highlights the potential of FRUHPC as a promising material for impact-resistant structures by creating a more favourable flexural failure mechanism, enhancing ductility and toughness under impact loading, and advancing the understanding of the role of fibres in structural performance.

CO_(2) mineralization by typical industrial solid wastes for preparing ultrafine CaCO_(3): A review

Mineral carbonation is a promising CO_(2) sequestration strategy that can utilize industrial wastes to convert CO_(2) into high-value CaCO_(3).This review summarizes the advancements in CO_(2) mineralization using typical industrial wastes to prepare ultrafine CaCO_(3).This work surveys the mechanisms of CO_(2) mineralization using these wastes and its capacities to synthesize CaCO_(3),evaluates the effects of carbonation pathways and operating parameters on the preparation of CaCO_(3),analyzes the current industrial application status and economics of this technology.Due to the large amount of impurities in solid wastes,the purity of CaCO_(3) prepared by indirect methods is greater than that prepared by direct methods.Crystalline CaCO_(3) includes three polymorphs.The polymorph of CaCO_(3) synthesized by carbonation process is determined the combined effects of various factors.These parameters essentially impact the nucleation and growth of CaCO_(3) by altering the CO_(2) supersaturation in the reaction system and the surface energy of CaCO_(3) grains.Increasing the initial pH of the solution and the CO_(2)flow rate favors the formation of vaterite,but calcite is formed under excessively high pH.Vaterite formation is favored at lower temperatures and residence time.With increased temperature and prolonged residence time,it passes through aragonite metastable phase and eventually transforms into calcite.Moreover,polymorph modifiers can decrease the surface energy of CaCO_(3) grains,facilitating the synthesis of vaterite.However,the large-scale application of this technology still faces many problems,including high costs,high energy consumption,low calcium leaching rate,low carbonation efficiency,and low product yield.Therefore,it is necessary to investigate ways to accelerate carbonation,optimize operating parameters,develop cost-effective agents,and understand the kinetics of CaCO_(3) nucleation and crystallization to obtain products with specific crystal forms.Furthermore,more studies on life cycle assessment(LCA)should be conducted to fully confirm the feasibility of the developed technologies.

Spatiotemporal mapping of(ultra‐)mafic magmatic mine areas:Implications of economic and political realities in China

The spatiotemporal extension/expansion of mine areas is affected by multiple factors.So far,very little has been done to examine the interaction between mine areas and political or economic realities.The(ultra‐)mafic magmatic mines in China played a specific role in supporting national development and providing an ideal research subject for monitoring their interrelationship.In this study,remote sensing and mining‐related GIS data were used to identify and analyze 1233(ultra‐)mafic magmatic mine area polygons in China,which covered approximately 322.96 km2 of land and included a V–Ti–Fe mine,a copper–nickel mine,a chromite mine,an asbestos mine,and a diamond mine.It was found that(1)the areal expansion of mines is significantly related to the mine types,perimeter,topography,and population density.(2)The mine area variation also reflects market and policy realities.The temporal expansion of the mine area from 2010 to 2020 followed an S‐shaped pattern(with the turning point occurring in 2014),closely related to iron overcapacity and tightened mining policies.(3)The complexity(D)of the mine area may reflect mine design and excavation practices.To be specific,lower D indicates early‐stage or artisanal/small‐scale mining,whereas higher D represents large‐scale mining.This study demonstrates that the detailed mapping of mine land can serve as an indicator to implement miningrelated market and policy changes.The(ultra‐)mafic mines area data set can be accessed at https://zenodo.org/record/7636616#.Y-p0uXaZOa0.

Xpert MTB/RIF Ultra在儿童结核诊断中的应用价值

目的:探讨Xpert MTB/RIF Ultra在儿童结核诊断中的应用价值。方法:选取2010年1月—2022年12月山东省公共卫生临床中心收治的150例患儿作为研究对象。根据临床综合诊断确诊结果将结核病感染患儿纳入试验组(n=100),将非结核病感染患儿纳入对照组(n=50)。计算不同标本类型的敏感度、特异度、阴性预测值、阳性预测值和准确度,评价Xpert MTB/RIF Ultra检出利福平(RIF)耐药性的效能。结果:Xpert MTB/RIF Ultra的检测所有标本总敏感度为77.00%,特异度为96.00%;合并肺内标本敏感度为92.85%,特异度为96.29%,其中肺内标本中肺泡灌洗液敏感度最高为100.00%;合并肺外标本敏感度为77.55%,特异度为95.65%,其中肺外标本中淋巴结敏感度最高为100.00%。结论:不同标本类型中Xpert MTB/RIF Ultra对儿童结核的检出率差异较大,在诊断肺内结核标本时,检测肺泡灌洗液标本价值最高,在诊断肺外结核标本时,检测淋巴结标本价值最高。

Xpert MTB/RIF Ultra对结核性脑膜炎的早期诊断价值

目的:评价Xpert MTB/RIF Ultra(Ultra)对结核性脑膜炎(TBM)的早期诊断价值。方法:对79例患者的临床资料进行分析,用Ultra、Xpert MTB/RIF(Xpert)、宏基因测序(mNGS)和分枝杆菌培养(MGIT)检测脑脊液(CSF)中的结核分枝杆菌。在临床诊断的基础上,分析各方法的检测性能和利福平药物敏感性。结果:Ultra的敏感度(56.4%)、曲线下面积(AUC值)和Kappa值(0.521)均高于MGIT(20%、0.600、0.236)、Xpert(40%、0.700、0.236)和mNGS(32.7%、0.664、0.352)。在31例Ultra阳性病例中,24例对利福平敏感,7例耐药性不确定。结论:与其他方法相比,Ultra检测脑脊液中结核分枝杆菌具有较高的敏感性。因此,Ultra可用于TBM的早期诊断。

Anisotropy of Trabecular Bone from Ultra-Distal Radius Digital X-Ray Imaging: Effects on Bone Mineral Density and Age

Background: When applied to trabecular bone X-ray images, the anisotropic properties of trabeculae located at ultra-distal radius were investigated by using the trabecular bone scores (TBS) calculated along directions parallel and perpendicular to the forearm. Methodology: Data from more than two hundred subjects were studied retrospectively. A DXA (GE Lunar Prodigy) scan of the forearm was performed on each subject to measure the bone mineral density (BMD) value at the location of ultra-distal radius, and an X-ray digital image of the same forearm was taken on the same day. The values of trabecular bone score along the direction perpendicular to the forearm, TBSx, and along the direction parallel to the forearm, TBSy, were calculated respectively. The statistics of TBSx and TBSy were calculated, and the anisotropy of the trabecular bone, which was defined as the ratio of TBSy to TBSx and changed with subjects’ BMD and age, was reported and analyzed. Results: The results show that the correlation coefficient between TBSx and TBSy was 0.72 (p BMD and age was reported. The results showed that decreased trabecular bone anisotropy was associated with deceased BMD and increased age in the subject group. Conclusions: This study shows that decreased trabecular bone anisotropy was associated with decreased BMD and increased age.

Xpert MTB/RIF Ultra在快速检测结核分枝杆菌和利福平耐药中的应用

目的探讨Xpert MTB/RIF Ultra在快速检测结核分枝杆菌和利福平耐药中的应用价值。方法收集2019年12月至2020年5月就诊于福州肺科医院的447例疑似肺结核患者的痰标本,分别进行MGIT960液体培养及药敏、Xpert MTB/RIF(Xpert)和Xpert Ultra检测,将检出MTB的菌株和痰液进行rpoB基因Sanger测序。以临床诊断结果为参照,比较MGIT960液体培养、Xpert、Xpert Ultra检测MTB的敏感度和特异度;分别以液体药敏和测序结果为金标准,评价Xpert Ultra检测MTB利福平耐药性的效能。结果以临床确诊为参照,Xpert Ultra敏感度高于液体培养和Xpert,差异有统计学意义(χ^(2)=28.97、164.86,P均<0.05),特异度与液体培养和Xpert比较差异无统计学意义(P均>0.05)。分别以利福平液体药敏表型结果和rpoB基因测序结果为金标准,Xpert Ultra的敏感度为88.89%和93.75%。同时经测序分析,35例利福平耐药样本中,rpoB的531位点突变最为常见,占48.57%。结论Xpert Ultra能快速检测痰液中的MTB及其利福平耐药性,对肺结核早期诊疗有良好的临床应用价值,适合在各级实验室推广。

A Study on the Effect of Low Calcium Ultra-fine Fly Ash as a Partial Sustainable Supplementary Material to Cement in Self-compacting Concrete

The aim and scope of the present study were to determine the efficacy of UFFA in evaluating the workability,static and dynamic stabilization properties,retention period,and slump loss of SCC systems in their fresh state,as well as their compressive strength at various ages.Microstructure(SEM and XRD)of blended SCC systems were studied.Also,the thermogravimetry behavior of blended SCC specimens were researched.According to the evaluated results,incorporating up to 20%UFFA into fresh concrete improved its performance due to its engineered fine particle size and spherical geometry,both of which contribute to the enhancement of characteristics.Blends of 25%and 30%of UFFA show effect on the water-binder ratio and chemical enhancer dosage,resulting in a loss of homogeneity in fresh SCC systems.The reduced particle size,increased amorphous content,and increased surface area all contribute to the pozzolanic reactivity of the early and later ages,resulting in denser packing and thus an increase in compressive strength.The experimental results indicate that UFFA enhances the properties of SCC in both its fresh and hardened states,which can be attributed to the particles’fineness and their relative effect on SCC.

Xpert MTB/RIF Ultra快速诊断涂阴肺结核的临床价值

目的评估超敏结核分枝杆菌和利福平耐药基因检测(XpertUltra)方案检测痰液及支气管肺泡灌洗液(BALF)标本在涂阴肺结核患者中早期、快速诊断的价值。方法选择2020年5月-2021年12月在山东省公共卫生临床中心就诊的痰涂片阴性疑似肺结核患者93例,其中临床诊断为涂阴肺结核57例,非肺结核36例。收集所有患者的痰液及BALF标本,分别采用Xpert Ultra、GeneXpert MTB/RIF(Xpert)、BACTEC MGIT 960培养(MGIT 960培养)进行检测。以临床诊断为参考标准,评价3种检测方案及相互联合检测痰液及BALF标本时诊断涂阴肺结核的敏感度、特异度及符合率。结果以临床诊断结果为参考标准,Xpert Ultra检测痰液标本对涂阴肺结核诊断的敏感度明显高于Xpert[56.14%(32/57)vs.36.84%(21/57),P=0.03]和MGIT960培养[56.14%(32/57)vs.33.33%(19/57),P=0.014];Xpert Ultra检测BALF标本对涂阴肺结核诊断的敏感度明显高于Xpert[75.44%(43/57)vs.56.14%(32/57),P=0.030]和MGIT960培养[75.44%(43/57)vs.38.60%(22/57),P<0.01]。3种检测方案及相互联合检测痰液标本诊断涂阴肺结核,受试者工作特征(ROC)曲线下面积(AUC)依次为:三者联合(0.807)>Xpert Ultra+Xpert(0.798)>Xpert Ultra+MGIT 960培养(0.789)>Xpert Ultra(0.781)>Xpert(0.684)>MGIT 960培养(0.667);检测BALF标本,AUC依次为:三者联合(0.895)=Xpert Ultra+Xpert(0.895)>XpertUltra+MGIT960培养(0.877)=XpertUltra(0.877)>Xpert(0.781)>MGIT960培养(0.693)。3种检测方案均未在入组患者中检测到利福平耐药。结论Xpert Ultra对早期、快速诊断涂阴肺结核具有较高的临床应用价值;其检测BALF的敏感度高于痰液标本,建议优先选择BALF标本。

Analytical Optimization of GeneXpert Ultra for Detection of Tuberculosis in CSF Samples

Detection of Mycobacterium tuberculosis complex (MTBC) in extrapulmonary specimens can be challenging due to their paucibacillary nature. This difficulty is especially true for cerebrospinal fluid (CSF), and the low sensitivity and specificity for diagnosis hampers rapid detection and treatment in vulnerable populations. GeneXpert MTB/RIF Ultra has been shown to provide rapid results for detection of MTBC and associated Rifampin resistance, but there is limited data regarding standardized methods for CSF processing on this assay. In this study, we sought to provide guidance regarding the best methods for CSF processing, including optimal volumes to test, length of incubation with sample reagent and finally effects of long-term freezing on detection.

Low Complexity Joint Spectrum Resource and Power Allocation for Ultra Dense Networks

In this paper,we propose a low complexity spectrum resource allocation scheme cross the access points(APs)for the ultra dense networks(UDNs),in which all the APs are divided into several AP groups(APGs)and the total bandwidth is divided into several narrow band spectrum resources and each spectrum resource is allocated to APGs independently to decrease the interference among the cells.Furthermore,we investigate the joint spectrum and power allocation problem in UDNs to maximize the overall throughput.The problem is formulated as a mixed-integer nonconvex optimization(MINCP)problem which is difficult to solve in general.The joint optimization problem is decomposed into two subproblems in terms of the spectrum allocation and power allocation respectively.For the spectrum allocation,we model it as a auction problem and a combinatorial auction approach is proposed to tackle it.In addition,the DC programming method is adopted to optimize the power allocation subproblem.To decrease the signaling and computational overhead,we propose a distributed algorithm based on the Lagrangian dual method.Simulation results illustrate that the proposed algorithm can effectively improve the system throughput.

Subducting passive continental margins with crustal (ultra)mafic intrusions: An underappreciated mechanism for recycling water back into the mantle

It is well known that outer rise bending-assisted oceanic plate hydration is an important mechanism for transporting substantial amounts of water into the mantle.A key question is:Are there other equally or more important water transport mechanisms?Here we propose,for the first time,that subducting passive continental margins,particularly those with crustal(ultra)mafic intrusions,play a critical role in recycling water back into the mantle.Evidence for this mechanism is the exceptionally high outer rise seismicity observed in a subducting passive continental margin(i.e.,the northeastern South China Sea continental margin)near the northern Manila trench,characterized by a high-velocity lower crust that has been attributed to(ultra)mafic intrusions.Our interpretation of this correlation between high outer rise seismicity and lower crust(ultra)mafic intrusions is that(ultra)mafic intrusions alter the crustal rheology and increase brittle deformation in the lower crust in this region,thereby promoting lithospheric fracturing and plate hydration,which is evidenced by increased outer rise seismicity.

Isolation Enhancement in a Compact Four-Element MIMO Antenna for Ultra-Wideband Applications

Mutual coupling reduction or isolation enhancement in antenna arrays is an important area of research as it severely affects the performance of an antenna.In this paper,a new type of compact and highly isolated Multiple-Input-Multiple-Output(MIMO)antenna for ultra-wideband(UWB)applications is presented.The design consists of four radiators that are orthogonally positioned and confined to a compact 40×40×0.8 mm3 space.The final antenna design uses an inverted L shape partial ground to produce an acceptable reflection coefficient(S11<−10 dB)in an entire UWB band(3.1–10.6)giga hertz(GHz).Moreover,the inter-element isolation has also been enhanced to>20 db for majority of the UWB band.The antenna was fabricated and tested with the vector network analyzer(VNA)and in an anechoic chamber for scattering parameters and radiation patterns.Furthermore,different MIMO diversity performance metrics are also measured to validate the proposed model.The simulation results and the experimental results from the constructed model agree quite well.The proposed antenna is compared with similar designs in recently published literature for various performance metrics.Because of its low envelope correlation coefficient(ECC<0.1),high diversity gain(DG>9.99 dB),peak gain of 4.6 dB,reduced channel capacity loss(CCL<0.4 b/s/Hz),and average radiation efficiency of over 85%,the proposed MIMO antenna is ideally suited for practical UWB applications.

Determination of Oleuropein in Cosmetics by Ultra Performance Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry

An ultrahigh performance liquid chromatography-triple quadrupole tandem mass spectrometry(UPLC-MS/MS)was established to quickly and accurately determine the content of oleuropein in cosmetics.The samples were extracted with methanol-aqueous solution,and the mobile phase with methanol-formic acid solution(0.1 mol/L)=40∶60 was separated by Agilent ZORBAX Eclipse Plus C18(2.1 mm×50 mm×1.8μm-Micron)column temperature 30℃,flow rate 0.3 mL/min.The MS end was detected by electrospray negative mode ionization(ESI-)and multiple reaction monitoring(MRM)mode.The results show a good linear relationship in the range of 0.002~5 mg/L,with a correlation coefficient R2 of 0.999,5.Method recovery range from 84.2%~107.6%and the relative standard deviation RSD is 5.8%.The detection time is 5 min,the detection limit is 0.000,6 mg/L,and the limit of quantification is 0.002 mg/L.This method has the advantages of convenient operation,low quantification limit,high precision and good repeatability,and is suitable for measuring the content of oleuropein in many kinds of cosmetics.

中国石油深层、超深层油气勘探进展与启示

近年来,中国石油天然气股份有限公司(以下简称中国石油)在陆上深层、超深层油气领域勘探持续获得突破,形成了一批规模储量区,展现出了巨大的油气勘探潜力。为了进一步明确未来中国石油深层、超深层油气勘探方向,在对中国石油近期油气勘探发展形势和新进展分析的基础上,将深层、超深层重点勘探突破进行了领域细分,并系统梳理了中国石油未来油气勘探重点区带并开展了排队优选研究,最后总结了各领域的勘探经验和启示。研究结果表明:①深层、超深层领域可细分为海相碳酸盐岩、碎屑岩及复杂岩性地层、前陆冲断带、深层页岩气4大领域;②向深层进军寻找突破是中国石油未来油气勘探的战略选择,也是未来中国石油油气勘探的重点,应分层次、突出重点部署,积极寻找规模新发现和大突破;③中国石油深层、超深层4大领域勘探程度低、剩余资源潜力大,根据目前勘探进展,初步梳理出40个未来油气勘探重点区带,其中石油地质资源量为39.4×10^(8)t,天然气地质资源量为39.6×10^(12)m^(3),油气勘探潜力巨大。结论认为,深层、超深层是规模油气发现的重大现实领域,保持战略定力、持续加大技术攻关和新领域的探索力度、不断创新理论认识、突破技术瓶颈是加快深层、超深层油气规模勘探开发的重要举措。

组合浸渍和超低温冻融预处理对真空冷冻干燥蓝莓品质的影响

为探究组合浸渍冻干保护剂(海藻糖-CaCl_(2))和超低温冻融预处理对蓝莓活性物质和品质的影响,该研究以直接冷冻干燥为对照组,以普通冻融(-20℃)、超低温快速冻融(-80℃)、超声波辅助冻干保护剂浸渍冻融(-20℃)、(-80℃)预处理后进行真空冷冻干燥为试验组,比较分析蓝莓活性物质(多酚氧化酶和过氧化物酶活性)、营养物质(维生素C、花青素、总酚、类黄酮)、质构特性(硬度、咀嚼性)等指标的变化情况,并在此基础上进行BoxBehnken三因素三水平试验设计。结果表明:单一的冻干保护剂浸渍处理或者超低温处理均不如两者组合效果理想,两者组合浸渍后-80℃冻融处理可以有效维持蓝莓硬度,提高蓝莓营养物质的保留度并减少真空冷冻干燥时间。冻融次数为2次,浸渍时间为3.7 h,单次冷冻时间为4.2 d时蓝莓综合指标最高,营养物质保留度最高。该研究阐述了冻干保护剂浸渍预处理与超低温冻融两者联合处理对真空冷冻干燥蓝莓品质提升的机理,探究了冻融次数、冷冻时间、浸渍时间对品质的影响,得出了真空冷冻干燥预处理的最佳参数,为蓝莓真空冷冻干燥技术的发展提供了新思路。

中国石化超深层钻完井关键技术挑战及展望

超深层是中国石化油气勘探开发的重要增储上产领域。针对超深层勘探开发需求和高温高压及复杂地质环境带来的工程挑战,中国石化持续开展关键技术攻关,在钻完井基础理论和方法、钻完井装备、高温井筒工作液、耐高温井下工具仪器和完井测试等方面取得关键技术进展,保障了120口超8 000 m油气井的安全钻探,钻深能力突破9 000 m,助推塔里木盆地顺北大型超深油气田建设、四川盆地海相特深层油气勘探开发突破,为保障超深层油气勘探开发提供了有力的工程技术支撑。随着油气勘探开发不断向更深层推进,技术升级转型需求日益迫切,需进一步夯实理论研究基础,突破耐高温关键工具仪器和井筒工作液,加快推进钻完井工程技术向数智化转型,为保障深层、超深层油气高效勘探开发和加快技术升级转型提供工程技术支撑。

基于分形理论的静压支承滑靴系统摩擦自适应特性分析

静压支承滑靴副比一般的滑动摩擦副具有更好的摩擦自适应特性,对滑靴的早期磨损有一定的修复效果,但其摩擦自适应机理目前尚不明确。为此,基于分形理论,采用分形维数、尺度系数等分形参数描述滑靴表面形貌,对摩擦自适应过程进行理论分析,开展磨损试验并以分时段更换试件的试验方法观察分形参数的变化情况,得到分形参数对摩擦学特性的影响规律,揭示滑靴摩擦自适应机理。结果表明,滑靴副在发生早期磨损后,分形维数呈增大-减小-再增大-再减小的变化过程,尺度系数和摩擦系数呈减小-增大-再减小-再增大的变化过程,滑靴在早期磨损阶段呈现出显著的摩擦自适应特性,其表面性能表现出劣化-修复-再劣化-再修复的变化特征。

塔里木油田超深层钻井技术进展及难题探讨

当前,塔里木油田以超深特深层为代表的深地油气资源开发对满足我国经济发展需求和保障能源安全至关重要。经过数十年的探索和实践,塔里木油田创新形成了超深复杂井井身结构设计、超深难钻地层钻井提速、超深大斜度井水平井钻井、超深复杂地层钻完井液、超深复杂地层固井、高温高压井完整性、超深复杂井井控等一系列超深层钻井技术,保障深地油气勘探获得重大突破并创造多项纪录。伴随超深井数量持续增加,工程地质条件更加复杂,井下环境更加苛刻,超深层钻井过程势必面临新的工程难题和挑战,严重制约深地油气资源安全高效开发。为此,通过概括塔里木油田钻井工程技术发展历程,系统梳理了深地钻井工程技术取得的主要技术进展,并结合新的勘探开发形势与油气开发要求,指出了塔里木油田钻井工程技术从超深层迈入特深层新时期的焦点问题及攻关发展方向,为国内外深地复杂油气井安全高效钻进提供借鉴和参考。

基极触发的雪崩晶体管导通机理

为研究基极触发的雪崩晶体管导通机理,建立了雪崩晶体管(n+⁃p⁃n⁃n+掺杂结构)的准三维器件模型和实验测试电路。研究了雪崩晶体管的温度分布特征,导通结束后器件最高温度约为417 K,位于电流通道内n⁃n+边界处。当集电极电压为300 V、基极触发电压为2.4 V时,仿真和实验获得的脉冲上升时间分别为2.4 ns、2.5 ns,半高宽(FWHM)分别为6.2 ns、5.8 ns,仿真和实验结果基本一致。研究结果表明:高触发脉冲电压幅值会加速晶体管内部电场的重建过程,从而缩短延迟时间,提高晶体管响应速度;负载阻抗会影响器件导通通道尺寸,负载阻抗减小时,电流密度提升,器件通过缩窄通道来提高通道内电流密度,宏观导通电阻降低。