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Research on shell-side heat and mass transfer with multi-component in LNG spiral-wound heat exchanger under sloshing conditions

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Petroleum Science 2024年第2期21卷 1333-1345页

作者： xue-Ping Du guang-Lei yu Ya-Cheng Xu Zhi-Jie Chen Nai-Liang Li Huan-guang Wang School of Low-carbon Energy and Power Engineering China University of Mining and TechnologyXuzhou221116JiangsuChina Key Laboratory of Thermo-Fluid Science and Engineering MOEXi'an Jiaotong UniversityXi'an710049ShaanxiChina Xi'an Aerospace Propulsion Test Technology Institute Xi'an710100ShaanxiChina

The spiral-wound heat exchanger(SWHE) is the primary low-temperature heat exchanger for large-scale LNG plants due to its high-pressure resistance, compact structure, and high heat exchange efficiency. This paper studied the shell-side heat and mass transfer characteristics of vapor-liquid two-phase mixed refrigerants in an SWHE by combining a multi-component model in FLUENT software with a customized multicomponent mass transfer model. Besides, the mathematical model under the sloshing condition was obtained through mathematical derivation, and the corresponding UDF code was loaded into FLUENT as the momentum source term. The results under the sloshing conditions were compared with the relevant parameters under the steady-state condition. The shell-side heat and mass transfer characteristics of the SWHE were investigated by adjusting the component ratio and other working conditions. It was found that the sloshing conditions enhance the heat transfer performance and sometimes have insignificant effects. The sloshing condition is beneficial to reduce the flow resistance. The comprehensive performance of multi-component refrigerants has been improved and the improvement is more significant under sloshing conditions, considering both the heat transfer and pressure *** results will provide theoretical support for the research and design of multi-component heat and mass transfer enhancement of LNG SWHE under ocean sloshing conditions.

关键词： Spiral-wound heat exchanger Sloshing conditions Two-phase flow Multi-component Heat and mass transfer

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Enhancing reversible hydrogen storage performance of 2LiBH_(4)–MgH_(2)via in-situ building heterogeneous nucleation sites

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Rare Metals 2024年第9期43卷 4367-4376页

作者： Wei Chen Ya-Hui Sun Tian Xu xue-Bin yu guang-Lin Xia Department of Materials Science Fudan UniversityShanghai 200433China

2LiBH_(4)-MgH_(2)composite is one of the most attractive reactive hydride composites with a theoretic hydrogen capacity of 10.8 wt%.However,the large nucleation restriction of MgB_(2)during the second step of dehydrogenation results in sluggish hydrogen storage kinetics and high operating temperature,which hinders its practical application as on-board hydrogen storage ***,Al3Ti doped Al nanoparticles(AT NPs)are prepared by a facile chemical reduction reaction to improve the hydrogen storage performance of 2LiBH_(4)-MgH_(2)*** the initial H_(2)desorption process,MgAlB_(4)and TiB_(2)that have identical crystal structure and low d-value mismatch with MgB_(2)resulting from the reaction between AT NPs and 2LiBH_(4)-MgH_(2)composite serve as effective nucleation sites for the formation of MgB_(2).As a result,the apparent activation energy of the two-step H_(2)desorption of AT NPs doped 2LiBH_(4)-MgH_(2)composite are notably decreased to(110.0±5.9)and(119.6±1.4)kJ·mol^(-1),which is 55.5 and 33.5 kJ·mol^(-1)lower than that of the undoped *** importantly,a reversible hydrogen storage capacity of 9.2 wt%after 10cycles of H_(2)desorption and adsorption could be achieved,corresponding to a capacity retention rate of 99%.The building of reactive bimetallic catalyst towards in situ formation of heterogeneous nucleation sites provides a new strategy for improving the hydrogen storage performance of reactive hydride composites.

关键词： Reversible hydrogen storage Reactive hydride composites Catalytic effects Heterogeneous nucleation

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Comparative observation of the effectiveness and safety of remimazolam besylate versus dexmedetomidine in gastrointestinal surgery in obese patients

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World Journal of Gastrointestinal Surgery 2024年第5期16卷 1320-1327页

作者： yu-Fu Deng xue-Run Jiang Zeng-guang Feng Department of Anesthesiology Xiangtan Central HospitalXiangtan 411100Hunan ProvinceChina

BACKGROUND Surgery for obese patients carries a higher risk of anesthesia complications compared with surgery for nonobese ***,a safe and effective anesthesia strategy is necessary to improve the medical experience of such patients and ensure their *** To compared the effectiveness and safety of remimazolam besylate versus dexmedetomidine(DEX)in gastrointestinal surgery in obese *** The study cohort included 60 obese patients undergoing gastrointestinal surgery between July 2021 and April 2023,comprising 30 patients who received DEX intervention(control group)and 30 patients who received remimazolam besylate intervention(research group).Heart rate(HR),respiratory rate(RR),mean arterial pressure(MAP),blood oxygen saturation(SpO_(2)),safety(nausea and vomiting,bradycardia,hypotension,and apnea),anesthesia and examination indices[induction time,anesthesia recovery time,and postanesthesia care unit(PACU)discharge time],sedation effect(Ramsay Sedation Scale),and postoperative pain visual analog scale were comparatively analyzed before anesthesia(T0),during anesthesia(T1),and after anesthesia(T2).RESULTS At T1,the research group showed significantly smaller changes in HR,RR,MAP,and SpO_(2) than the control group,with a significantly lower adverse reaction rate and shorter induction,anesthesia recovery,and PACU discharge ***,the intra-and postoperative Ramsay Sedation Scale scores were statistically higher in the research group than in the control *** Remimazolam besylate was significantly more effective than DEX in gastrointestinal surgery in obese patients and had a higher safety profile and value in clinical promotion.

关键词： Remimazolam besylate Dexmedetomidine Obesity Gastrointestinal surgery Effectiveness Safety

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Effects of preoperative ketamine on the endocrine-metabolic and inflammatory response to laparoscopic surgery

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Chinese Medical Journal 2011年第22期124卷 3721-3725页

作者： DU Jin HUANG yu-guang yu xue-rong ZHAO Na Department of Anaesthesiology Subei People＇s Hospital Yangzhou University Yangzhou Jiangsu 225001 China

Background Ketamine is hypothesized to reduce perioperative endocrine-metabolic and inflammatory responses in cardiac surgery patients. This randomized, placebo-controlled, double-blind study was performed to determine whether perioperative endocrine-metabolic and inflammatory responses are attenuated by preoperative administration of ketamine to healthy females receiving elective laparoscopic surgery. Methods Forty female patients with American Society of Anesthesiologist classification Ⅰ or Ⅱwho elected to receive gynecological laparoscopic surgery were randomly assigned to the ketamine-treated （group K; n = 20） or control （group C n = 20） group. At 2 minutes prior to induction patients in group K received ketamine （0.25 mg/kg） whereas those in group C received normal saline. All patients received standardized general anesthesia. Serum glucose and cortisol values were measured before ketamine administration （TO）, 2 minutes after tracheal intubation （T1）, 30 minutes after skin incision （T2）, 2 minutes after tracheal extubation （T3） and 1 hour postoperatively （T4）. Serum interleukin-6 and tumor necrosis factor-α values were determined at TO and T4. Postoperative analgesic efficacy, side effects of administered drugs, and time to discharge were recorded. Results Compared with subjects in group C, those in group K had lower serum glucose values at T1, T2, T3 and T4 and lower serum cortisol values at T4 （P 〈0.05）. Postoperative interleukin-6 and tumor necrosis factor-α concentrations for group K were lower than those for group C （P 〈0.05）. Postoperative visual analog scale scores at rest, cumulative fentanyl consumption, and time to discharge were lower in group K as compared to group C （P 〈0.05）. No significant differences in drug side effects were observed postoperatively between the two groups. Conclusion Endocrine-metabolic and inflammatory responses to laparoscopic surgery are attenuated in part by Dre-incisienal administration of ketamine.

关键词： endocrine-metabolic response inflammatory response ketamine laparoscopic surgery preemptive analgesia

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Heterogeneous body compositions and all-cause mortality in acute coronary syndrome patients:a ten-year retrospective cohort study

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Journal of Geriatric Cardiology 2024年第5期21卷 534-541页

作者： guang-Zhi LIAO Lin BAI yu-Yang YE xue-Feng CHEN Xin-Ru HU Yong PENG Department of Cardiology West China HospitalSichuan UniversityChengduSichuanChina

BACKGROUND The association of different body components,including lean mass and body fat,with the risk of death in acute coronary syndrome(ACS)patients are *** We enrolled adults diagnosed with ACS at our center between January 2011 and December 2012 and obtained fol-low-up outcomes via telephone *** used restricted cubic splines(RCS)with the Cox proportional hazards model to analyze the associations between body mass index(BMI),predicted lean mass index(LMI),predicted body fat percentage(BF),and the value of LMI/BF with 10-year *** also examined the secondary outcome of death during *** During the maximum 10-year follow-up of 1398 patients,331 deaths(23.6%)occurred,and a U-shaped relationship was found between BMI and death risk(P_(nonlinearity)=0.03).After adjusting for age and history of diabetes,the overweight group(24≤BMI<28 kg/m^(2))had the lowest mortality(HR=0.53,95%CI:0.29-0.99).Predicted LMI and LMI/BF had an inverse linear relationship with a 10-year death risk(P_(nonlinearity)=0.24 and P_(nonlinearity)=0.38,respectively),while an increase in BF was associ-ated with increased mortality(P_(nonlinearity)=0.64).During hospitalization,31 deaths(2.2%)were recorded,and the associations of the indicators with in-hospital mortality were consistent with the long-term outcome *** Our study provides new insight into the“obesity paradox”in ACS patients,highlighting the importance of considering body composition *** LMI and BF may serve as useful tools for assessing nutritional status and predicting the prognosis of ACS,based on their linear associations with all-cause mortality.

关键词： patients mortality coronary

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p-d Orbital Hybridization Engineered Single-Atom Catalyst for Electrocatalytic Ammonia Synthesis

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Energy & Environmental Materials 2024年第2期7卷 119-125页

作者： Jingkun yu xue Yong Siyu Lu Green Catalysis Center and College of ChemistryZhengzhou UniversityZhengzhou 450001China Department of Chemistry University of SheffieldSheffieldS37HFUK

The rational design of metal single-atom catalysts(SACs)for electrochemical nitrogen reduction reaction(NRR)is ***-dimensional metal-organic frameworks(2DMOFs)is a unique class of promising *** to now,the roles of individual metals,coordination atoms,and their synergy effect on the electroanalytic performance remain ***,in this work,a series of 2DMOFs with different metals and coordinating atoms are systematically investigated as electrocatalysts for ammonia synthesis using density functional theory *** a specific metal,a proper metal-intermediate atoms p-d orbital hybridization interaction strength is found to be a key indicator for their NRR catalytic *** hybridization interaction strength can be quantitatively described with the p-/d-band center energy difference(Δd-p),which is found to be a sufficient descriptor for both the p-d hybridization strength and the NRR *** maximum free energy change(ΔG_(max))andΔd-p have a volcanic relationship with OsC_(4)(Se)_(4)located at the apex of the volcanic curve,showing the best NRR *** asymmetrical coordination environment could regulate the band structure subtly in terms of band overlap and *** work may shed new light on the application of orbital engineering in electrocatalytic NRR activity and especially promotes the rational design for SACs.

关键词： first-principle calculations Nitrogen reduction p-d orbital hybridization single-atom catalysts

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Full waveform inversion based on hybrid gradient

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Petroleum Science 2024年第3期21卷 1660-1670页

作者： Chuang Xie Zhi-Liang Qin Jian-Hua Wang Peng Song Heng-guang Shen Sheng-Qi yu Ben-Jun Ma xue-Qin Liu Qingdao Innovation and Development Base Harbin Engineering UniversityQingdao266000ShandongChina Qingdao Innovation and Development Center Harbin Engineering UniversityQingdao266000ShandongChina CNOOC Research Institute Co. Ltd.Beijing100028China College of Marine Geoscience Ocean University of ChinaQingdao266100ShandongChina Weihai Sunfull Geophysical Exploration Equipment Co. Ltd.Weihai264209ShandongChina

The low-wavenumber components in the gradient of full waveform inversion(FWI)play a vital role in the stability of the ***,when FWI is implemented in some high frequencies and current models are not far away from the real velocity model,an excessive number of low-wavenumber components in the gradient will also reduce the convergence rate and inversion *** solve this problem,this paper firstly derives a formula of scattering angle weighted gradient in FWI,then proposes a hybrid *** hybrid gradient combines the conventional gradient of FWI with the scattering angle weighted gradient in each inversion frequency band based on an empirical formula derived *** weighted hybrid mode,we can retain some low-wavenumber components in the initial lowfrequency inversion to ensure the stability of the inversion,and use more high-wavenumber components in the high-frequency inversion to improve the convergence *** results of synthetic data experiment demonstrate that compared to the conventional FWI,the FWI based on the proposed hybrid gradient can effectively reduce the low-wavenumber components in the gradient under the premise of ensuring inversion *** also greatly enhances the convergence rate and inversion accuracy,especially in the deep part of the *** the field marine seismic data experiment also illustrates that the FWI based on hybrid gradient(HGFWI)has good stability and adaptability.

关键词： Full waveform inversion Hybrid gradient Scattering angle weighted Low-wavenumber component

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Narrative review of latest research progress about robotic percutaneous coronary intervention

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Journal of Geriatric Cardiology 2024年第8期21卷 816-825页

作者： Zhen-yu LIU guang-Yao ZHAI Department of Clinical Medicine Beijing Luhe HospitalCapital Medical UniversityBeijingChina Department of Cardiology Beijing Luhe HospitalCapital Medical UniversityBeijingChina

Robotic percutaneous coronary intervention(R-PCI)is a novel technology in which operators can manipulate guidewires and catheter devices in interventional *** approach provides great benefits to interventional cardiologists in terms of reducing both radiation exposure and orthopedic *** large,high-quality cohort studies have confirmed the short-term safety and high technical success rate of ***,randomized long-term data are still needed before adopting them as part of standard coronary ***,tele-stenting for complex coronary lesions has significant potential for *** need to overcome the present relevant challenges for its application such as inherent delays,bedside care for unstable patients from R-PCIs to manual PCIs(M-PCIs),incompatibility for a thrombus aspiration catheter and heavily calcified *** is a great future in laboratory workflow teams,3D-printed anatomical models and multiple joint collaborative control *** narrative review summarizes the latest developments in R-PCI,with a focus on developments in robotic technology,and discusses the current and future potential use of R-PCI in clinical practice globally.

关键词： coronary injuries unstable

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Derivatives of Intersection Local Time for Two Independent Symmetricα-stable Processes

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Acta Mathematica Sinica,English Series 2024年第5期40卷 1273-1292页

作者： Huan ZHOU guang Jun SHEN Qian yu Department of Mathematics Anhui Normal UniversityWuhu 241002P.R.China Department of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106P.R.China Key Laboratory of Mathematical Modelling and High Performance Computing of Air Vehicles(NUAA) MIITNanjing 211106P.R.China

In this paper,we consider the derivatives of intersection local time for two independent d-dimensional symmetricα-stable processes X^(α) and X^(α)with respective indices α and α.We first study the sufficient condition for the existence of the derivatives,which makes us obtain the exponential integrability and H?lder *** we show that this condition is also necessary for the existence of derivatives of intersection local time at the ***,we also study the power variation of the derivatives.

关键词： Symmetric stable processes intersection local time exponential integrability power variation

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Estimation of surface geometry on combustion characteristics of AP/HTPB propellant under rapid depressurization

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Defence Technology（防务技术） 2024年第3期33卷 546-558页

作者： Kaixuan Chen Zhenwei Ye Xiaochun xue Yonggang yu School of Energy and Power Engineering Nanjing University of Science and TechnologyNanjing 210094JiangsuChina School of Science Hangzhou Dianzi UniversityHangzhou 310018ZhejiangChina

The 2D sandwich model serves as a potent tool in exploring the influence of surface geometry on the combustion attributes of Ammonium perchlorate/Hydroxyl-terminated polybutadiene(AP/HTPB)propellant under rapid pressure *** thickness of the sandwich propellant is derived from slicing the 3D random particle packing,an approach that enables a more effective examination of the micro-flame *** analysis of the predicted burning characteristics has been performed with experimental *** findings demonstrate a reasonable agreement,thereby validating the precision and soundness of the *** on the typical rapid depressurization environment of solid rocket motor(initial combustion pressure is 3 MPa and the maximum depressurization rate is 1000 MPa/s).A-type(a flatter surface),B-type(AP recesses from the combustion surface),and C-type(AP protrudes from the combustion surface)propellant combustion processes are numerically *** comparison of the evolution of gas-phase flame between 0.1 and 1 ms,it is discerned that the flame strength and form created by the three sandwich models differ significantly at the beginning stage of depressurization,with the flame structures gradually becoming harmonized over *** are drawn by comparison extinction times:the surface geometry plays a pivotal role in the combustion process,with AP protrusion favoring combustion the most.

关键词： AP/HTPB propellant BDP model Rapid pressure decay Burning surface geometry

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