关于弱(α,δ)-Reversible环

本文推广reversible环的概念,提出弱(α,δ)-Reversible环的概念,研究弱(α,δ)-Reversible环上的扩张及与弱(α,δ)-symmetric环的关系.

Giant reversible barocaloric effects with high thermal cycle stability in epoxybonded(MnCoGe)_(0.96)(CuCoSn)_(0.04) composite

Hexagonal MnMX-based(M=Co or Ni,X=Si or Ge)alloys exhibit giant reversible barocaloric effects.However,giant volume expansion would result in the as-cast MnMX ingots fragmenting into powders,and inevitably bring the deterioration of mechanical properties and formability.Grain fragmentation can bring degradation of structural transformation entropy change during cyclic application and removal of pressure.In this paper,giant reversible barocaloric effects with high thermal cycle stability can be achieved in the epoxy bonded(MnCoGe)0.96(CuCoSn)0.04 composite.Giant reversible isothermal entropy change of 43.0 J·kg^(−1)·K^(−1) and adiabatic temperature change from barocaloric effects(ΔT_(BCE))of 15.6 K can be obtained within a wide temperature span of 30 K at 360 MPa,which is mainly attributed to the integration of the change in the transition temperature driven by pressure of−101 K·GPa^(−1) and suitable thermal hysteresis of 11.1 K.Further,the variation of reversibleΔ_(TBCE) against the applied hydrostatic pressure reaches up to 43 K·GPa^(−1),which is at the highest level among the other reported giant barocaloric compounds.More importantly,after 60 thermal cycles,the composite does not break and the calorimetric curves coincide well,demonstrating good thermal cycle stability.

Surviving winter on the Qinghai-Xizang Plateau:Extensive reversible protein phosphorylation plays a dominant role in regulating hypometabolism in hibernating Nanorana parkeri

Changes in protein abundance and reversible protein phosphorylation(RPP)play important roles in regulating hypometabolism but have never been documented in overwintering frogs at high altitudes.To test the hypothesis that protein abundance and phosphorylation change in response to winter hibernation,we conducted a comprehensive and quantitative proteomic and phosphoproteomic analysis of the liver of the Xizang plateau frog,Nanorana parkeri,living on the Qinghai-Xizang Plateau.In total,5170 proteins and 5695 phosphorylation sites in 1938 proteins were quantified.Based on proteomic analysis,674 differentially expressed proteins(438 up-regulated,236 down-regulated)were screened in hibernating N.parkeri versus summer individuals.Functional enrichment analysis revealed that higher expressed proteins in winter were significantly enriched in immune-related signaling pathways,whereas lower expressed proteins were mainly involved in metabolic processes.A total of 4251 modified sites(4147 up-regulated,104 down-regulated)belonging to 1638 phosphoproteins(1555 up-regulated,83 down-regulated)were significantly changed in the liver.During hibernation,RPP regulated a diverse array of proteins involved in multiple functions,including metabolic enzymatic activity,ion transport,protein turnover,signal transduction,and alternative splicing.These changes contribute to enhancing protection,suppressing energy-consuming processes,and inducing metabolic depression.Moreover,the activities of phosphofructokinase,glutamate dehydrogenase,and ATPase were all significantly lower in winter compared to summer.In conclusion,our results support the hypothesis and demonstrate the importance of RPP as a regulatory mechanism when animals transition into a hypometabolic state.

Dialectical Thermodynamics’Solution to the Conceptual Imbroglio That Is the Reversible Path

According to the second law of thermodynamics, as currently understood, any given transit of a system along the reversible path proceeds with a total entropy change equal to zero. The fact that this condition is also the identifier of thermodynamic equilibrium, makes each and every point along the reversible path a state of equilibrium, and the reversible path, as expressed by a noted thermodynamic author, “a dense succession of equilibrium states”. The difficulties with these notions are plural. The fact, for example, that systems need to be forced out of equilibrium via the expenditure of work, would make any spontaneous reversible process a consumer of work, this in opposition to common thermodynamic wisdom that makes spontaneous reversible processes the most efficient transformers of work-producing-potential into actual work. The solution to this and other related impasses is provided by Dialectical Thermodynamics via its previously proved notion assigning a negative entropy change to the energy upgrading process represented by the transformation of heat into work. The said solution is here exemplified with the ideal-gas phase isomerization of butane into isobutane.

Adrenaline in pulp capping treatment of reversible pulpitis

BACKGROUND The role of epinephrine in the treatment of pulp capping in patients with reversible pulpitis is not clear.AIM To explore the role of epinephrine in the treatment of pulp capping in patients with reversible pulpitis.METHODS A total of 100 patients with reversible pulpitis who were treated in Anhui Jieshou People's Hospital from January 2020 to December 2021 were included in the study.They were categorized into an observation group(n=50;treatment with adrenaline)and a control group(n=50;treatment with zinc oxide eugenol paste).The 24-h postoperative pain,regression time of gingival congestion and redness,clinical efficacy,and incidence of adverse reactions were compared between the groups.Patients were further categorized into the ineffective and effective treatment groups based on clinical efficacy.Logistic multiple regression analysis explored factors affecting the efficacy of pulp capping treatment.RESULTS A significant difference in 24-h postoperative pain was observed between the groups(P<0.05),with a higher proportion of grade I pain noted in the observation group than in the control group(P<0.01).The regression time of gingival congestion and swelling was lower in the observation group(2.61±1.44 d and 2.73±1.36 d,respectively)than in the control group(3.85±1.47 d and 4.28±1.61 d,respectively)(P<0.05).The 2-wk postoperative total effective rate was lower in the control group(80.00%)than in the observation group(94.00%)(P<0.05).The incidence of adverse reactions was not significantly different between the control(14.00%)and observation(12.00%)groups(P>0.05).The proportion of adrenaline usage was lower(P<0.05)and that of anaerobic digestion by Streptococcus and Fusobacterium nucleatum was higher in the ineffective treatment group than in the effective treatment group(P<0.05).Logistic multiple regression analysis revealed adrenaline as a protective factor(P<0.05)and anaerobic digestion by Streptococcus and F.nucleatum as risk factors for pulp capping in reversible pulpitis(P<0.05).CONCLUSION Adrenaline demonstrated therapeutic efficacy in pulp capping treatment for reversible pulpitis,reducing pain and improving clinical symptoms safely.It is a protective factor for pulp capping,whereas Streptococcus and F.nucleatum are risk factors.Targeted measures can be implemented to improve clinical efficacy.

Improvement effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)on hydrogen storage performance of MgH_(2)

The hydrogen absorption/desorption kinetic properties of MgH_(2)can be effectively enhanced by doping specific catalysts.In this work,MOFs-derived NiCu@C nanoparticles(~15 nm)with regular core-shell structure were successfully prepared and introduced into MgH_(2)(denoted as MgH_(2)-NiCu@C).The onset and peak temperatures of hydrogen desorption of MgH_(2)-11 wt.%NiCu@C are 175.0℃and282.2℃,respectively.The apparent activation energy of dehydrogenated reaction is 77.2±4.5 kJ/mol for MgH_(2)-11 wt.%NiCu@C,which is lower than half of that of the as-milled MgH_(2).Moreover,MgH_(2)-11 wt.%NiCu@C displays great cyclic stability.The strengthening"hydrogen pumping"effect of reversible solid solutions Mg_(2)Ni(Cu)/Mg_(2)Ni(Cu)H_(4)is proposed to explain the remarkable improvement in hydrogen absorption/desorption kinetic properties of MgH_(2).This work offers a novel perspective for the design of bimetallic nanoparticles and beyond for application in hydrogen storage and other energy related fields.

Critical Solvation Structures Arrested Active Molecules for Reversible Zn Electrochemistry

Aqueous Zn-ion batteries(AZIBs)have attracted increasing attention in next-generation energy storage systems due to their high safety and economic.Unfortunately,the side reactions,dendrites and hydrogen evolution effects at the zinc anode interface in aqueous electrolytes seriously hinder the application of aqueous zinc-ion batteries.Here,we report a critical solvation strategy to achieve reversible zinc electrochemistry by introducing a small polar molecule acetonitrile to form a“catcher”to arrest active molecules(bound water molecules).The stable solvation structure of[Zn(H_(2)O)_(6)]^(2+)is capable of maintaining and completely inhibiting free water molecules.When[Zn(H_(2)O)_(6)]^(2+)is partially desolvated in the Helmholtz outer layer,the separated active molecules will be arrested by the“catcher”formed by the strong hydrogen bond N-H bond,ensuring the stable desolvation of Zn^(2+).The Zn||Zn symmetric battery can stably cycle for 2250 h at 1 mAh cm^(-2),Zn||V_(6)O_(13) full battery achieved a capacity retention rate of 99.2%after 10,000 cycles at 10 A g^(-1).This paper proposes a novel critical solvation strategy that paves the route for the construction of high-performance AZIBs.

Rational Design of Ruddlesden-Popper Perovskite Ferrites as Air Electrode for Highly Active and Durable Reversible Protonic Ceramic Cells

Reversible protonic ceramic cells(RePCCs)hold promise for efficient energy storage,but their practicality is hindered by a lack of high-performance air electrode materials.Ruddlesden-Popper perovskite Sr_(3)Fe_(2)O_(7−δ)(SF)exhibits superior proton uptake and rapid ionic conduction,boosting activity.However,excessive proton uptake during RePCC operation degrades SF’s crystal structure,impacting durability.This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes,incorporating Sr-deficiency and Nb-substitution to create Sr_(2.8)Fe_(1.8)Nb_(0.2)O_(7−δ)(D-SFN).Nb stabilizes SF’s crystal,curbing excessive phase formation,and Sr-deficiency boosts oxygen vacancy concentration,optimizing oxygen transport.The D-SFN electrode demonstrates outstanding activity and durability,achieving a peak power density of 596 mW cm^(−2)in fuel cell mode and a current density of−1.19 A cm^(−2)in electrolysis mode at 1.3 V,650℃,with excellent cycling durability.This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.

Reversed charge transfer induced by nickel in Fe-Ni/Mo_(2)C@nitrogen-doped carbon nanobox for promoted reversible oxygen electrocatalysis

The interaction between metal and support is critical in oxygen catalysis as it governs the charge transfer between these two entities,influences the electronic structures of the supported metal,affects the adsorption energies of reaction intermediates,and ultimately impacts the catalytic performance.In this study,we discovered a unique charge transfer reversal phenomenon in a metal/carbon nanohybrid system.Specifically,electrons were transferred from the metal-based species to N-doped carbon,while the carbon support reciprocally donated electrons to the metal domain upon the introduction of nickel.This led to the exceptional electrocatalytic performances of the resulting Ni-Fe/Mo_(2)C@nitrogen-doped carbon catalyst,with a half-wave potential of 0.91 V towards oxygen reduction reaction(ORR)and a low overpotential of 290 m V at 10 mA cm^(-2)towards oxygen evolution reaction(OER)under alkaline conditions.Additionally,the Fe-Ni/Mo_(2)C@carbon heterojunction catalyst demonstrated high specific capacity(794 mA h g_(Zn)~(-1))and excellent cycling stability(200 h)in a Zn-air battery.Theoretical calculations revealed that Mo_(2)C effectively inhibited charge transfer from Fe to the support,while secondary doping of Ni induced a charge transfer reversal,resulting in electron accumulation in the Fe-Ni alloy region.This local electronic structure modulation significantly reduced energy barriers in the oxygen catalysis process,enhancing the catalytic efficiency of both ORR and OER.Consequently,our findings underscore the potential of manipulating charge transfer reversal between the metal and support as a promising strategy for developing highly-active and durable bi-functional oxygen electrodes.

A Dual Domain Robust Reversible Watermarking Algorithm for Frame Grouping Videos Using Scene Smoothness

The proposed robust reversible watermarking algorithm addresses the compatibility challenges between robustness and reversibility in existing video watermarking techniques by leveraging scene smoothness for frame grouping videos.Grounded in the H.264 video coding standard,the algorithm first employs traditional robust watermark stitching technology to embed watermark information in the low-frequency coefficient domain of the U channel.Subsequently,it utilizes histogram migration techniques in the high-frequency coefficient domain of the U channel to embed auxiliary information,enabling successful watermark extraction and lossless recovery of the original video content.Experimental results demonstrate the algorithm’s strong imperceptibility,with each embedded frame in the experimental videos achieving a mean peak signal-to-noise ratio of 49.3830 dB and a mean structural similarity of 0.9996.Compared with the three comparison algorithms,the performance of the two experimental indexes is improved by 7.59%and 0.4%on average.At the same time,the proposed algorithm has strong robustness to both offline and online attacks:In the face of offline attacks,the average normalized correlation coefficient between the extracted watermark and the original watermark is 0.9989,and the average bit error rate is 0.0089.In the face of online attacks,the normalized correlation coefficient between the extracted watermark and the original watermark is 0.8840,and the mean bit error rate is 0.2269.Compared with the three comparison algorithms,the performance of the two experimental indexes is improved by 1.27%and 18.16%on average,highlighting the algorithm’s robustness.Furthermore,the algorithm exhibits low computational complexity,with the mean encoding and the mean decoding time differentials during experimental video processing being 3.934 and 2.273 s,respectively,underscoring its practical utility.

Reversible Data Hiding Algorithm in Encrypted Images Based on Adaptive Median Edge Detection and Ciphertext-Policy Attribute-Based Encryption

With the rapid advancement of cloud computing technology,reversible data hiding algorithms in encrypted images(RDH-EI)have developed into an important field of study concentrated on safeguarding privacy in distributed cloud environments.However,existing algorithms often suffer from low embedding capacities and are inadequate for complex data access scenarios.To address these challenges,this paper proposes a novel reversible data hiding algorithm in encrypted images based on adaptive median edge detection(AMED)and ciphertext-policy attributebased encryption(CP-ABE).This proposed algorithm enhances the conventional median edge detection(MED)by incorporating dynamic variables to improve pixel prediction accuracy.The carrier image is subsequently reconstructed using the Huffman coding technique.Encrypted image generation is then achieved by encrypting the image based on system user attributes and data access rights,with the hierarchical embedding of the group’s secret data seamlessly integrated during the encryption process using the CP-ABE scheme.Ultimately,the encrypted image is transmitted to the data hider,enabling independent embedding of the secret data and resulting in the creation of the marked encrypted image.This approach allows only the receiver to extract the authorized group’s secret data,thereby enabling fine-grained,controlled access.Test results indicate that,in contrast to current algorithms,the method introduced here considerably improves the embedding rate while preserving lossless image recovery.Specifically,the average maximum embedding rates for the(3,4)-threshold and(6,6)-threshold schemes reach 5.7853 bits per pixel(bpp)and 7.7781 bpp,respectively,across the BOSSbase,BOW-2,and USD databases.Furthermore,the algorithm facilitates permission-granting and joint-decryption capabilities.Additionally,this paper conducts a comprehensive examination of the algorithm’s robustness using metrics such as image correlation,information entropy,and number of pixel change rate(NPCR),confirming its high level of security.Overall,the algorithm can be applied in a multi-user and multi-level cloud service environment to realize the secure storage of carrier images and secret data.

Calcineurin inhibitors-related posterior reversible encephalopathy syndrome in liver transplant recipients: Three case reports and review of literature

BACKGROUND Posterior reversible encephalopathy syndrome(PRES),characterized by acute neurological deterioration and extensive white matter lesions on T2-fluid attenuated inversion recovery magnetic resonance imaging(MRI),is increasingly associated with calcineurin inhibitors(CNI)-related neurotoxicity.Prompt diagnosis is crucial,as early intervention,including the modification or discontinuation of CNI therapy,strict blood pressure management,corticosteroid treatment,and supportive care can significantly improve patient outcomes and prognosis.The growing clinical recognition of CNI-related PRES underscores the importance of identifying and managing this condition in patients presenting with acute neurological symptoms.CASE SUMMARY This report describes three cases of liver transplant recipients who developed PRES.The first case involves a 60-year-old woman who experienced seizures,aphasia,and hemiplegia on postoperative day(POD)9,with MRI revealing ischemic foci followed by extensive white matter lesions.After replacing tacrolimus,her symptoms improved,and no significant MRI abnormalities were observed after three years of follow-up.The second case concerns a 54-year-old woman with autoimmune hepatitis who developed headaches,seizures,and extensive white matter demyelination on MRI on POD24.Following the switch to rapamycin and the initiation of corticosteroids,her symptoms resolved,and she was discharged on POD95.The third case details a 60-year-old woman with hepatocellular carcinoma who developed PRES,evidenced by brain MRI abnormal-ities on POD11.Transitioning to rapamycin and corticosteroid therapy led to her full recovery,and she was discharged on POD22.These cases highlight the critical importance of early diagnosis,CNI modification,and stringent management in improving outcomes for liver transplant recipients with CNI related PRES.CONCLUSION Clinical manifestations,combined with characteristic MRI findings,are crucial in diagnosing PRES among organ transplant recipients.However,when standard treatments are ineffective or MRI results are atypical,alternative diagnoses should be taken into considered.

Reversible Semi-Fragile Watermarking Technique for Integrity Control of Relational Database

Reversible watermarking schemes for relational database are usually classified into two groups: robust schemes and fragile schemes. The main limitation of existing reversible fragile methods is that they cannot differentiate between legal and malicious modifications. In this paper, we introduce a novel lossless semi-fragile scheme based on prediction-error expansion for content protection of relational database. In the proposed method, all attributes in a database relation are first classified according to their sensitivity to legitimate updates. Then, the watermark is embedded by expanding the prediction error of the two least significant digits of securely selected attributes. At watermark extraction, the proposed method has the ability to fully restore the original data while detecting and localizing tampering. The applicability of our method is demonstrated theoretically and experimentally.

Tacrolimus-induced posterior reversible encephalopathy syndrome following liver transplantation

In this editorial,we talk about a compelling case focusing on posterior reversible encephalopathy syndrome(PRES)as a complication in patients undergoing liver transplantation and treated with Tacrolimus.Tacrolimus(FK 506),derived from Streptomyces tsukubaensis,is a potent immunosuppressive macrolide.It inhibits Tcell transcription by binding to FK-binding protein,and is able to amplify glucocorticoid and progesterone effects.Tacrolimus effectively prevents allograft rejection in transplant patients but has adverse effects such as Tacrolimus-related PRES.PRES presents with various neurological symptoms alongside elevated blood pressure,and is primarily characterized by vasogenic edema on neuroimaging.While computed tomography detects initial lesions,magnetic resonance imaging,especially the Fluid-Attenuated Inversion Recovery sequence,is superior for diagnosing cortical and subcortical edema.Our discussion centers on the incidence of PRES in solid organ transplant recipients,which ranges between 0.5 to 5+ACU-,with varying presentations,from seizures to visual disturbances.The case of a 66-year-old male status post liver transplantation highlights the diagnostic and management challenges associated with Tacrolimus-related PRES.Radiographically evident in the parietal and occipital lobes,PRES underlines the need for heightened vigilance among healthcare providers.This editorial emphasizes the importance of early recognition,accurate diagnosis,and effective management of PRES to optimize outcomes in liver transplant patients.The case further explores the balance between the efficacy of immunosuppression with Tacrolimus and its potential neurological risks,underlining the necessity for careful monitoring and intervention strategies in this patient population.

食品中多环芳烃的来源、污染状况与检测分析

多环芳烃(polycyclic aromatic hydrocarbons,PAHs)是一类持久性的有机污染物,具有致癌、致畸、致突变等毒性,广泛存在于食品、特别是烟熏食品中,过量摄入将严重危害人体健康。许多国家通过制定严格的限量标准、加强检验检测等措施对食品中的PAHs进行防控,但随着工业化的快速发展,煤、石油等燃料的大量使用,食品中PAHs污染的问题依然突出,其在食品中仍普遍被检出,已成为影响食品安全的主要风险来源之一,关于食品中PAHs的污染来源、监测分析和检测技术等方面的研究也日益增多。本文概述了PAHs对农作物的影响,分析了食品中PAHs的主要来源和污染状况,从样品前处理和测定分析两个方面,综述了食品中PAHs的主要检测技术,评述了其优缺点,并提出了今后研究工作的建议,以期为食品中PAHs的监测分析、预防控制和深入研究提供参考。

2020—2022年安徽省猪圆环病毒2型和3型流行情况调查

为了解安徽省猪圆环病毒病(PCVAD)流行情况,2020—2022年于安徽省13个定点监测点采集950份病原学样品和650份血清学样品,采用荧光PCR方法进行猪圆环病毒2型(PCV2)和猪圆环病毒3型(PCV3)病原检测,采用间接ELISA方法进行PCV2抗体检测。结果显示:安徽省PCV2抗体阳性率逐年升高,大型养殖场的抗体阳性率显著高于中、小型养殖场(P<0.05);PCV2病原阳性率呈下降趋势,PCV3呈上升趋势,且同一年份的PCV2病原阳性率均显著高于PCV3(P<0.05);屠宰场的PCV2和PCV3病原阳性率均显著高于养殖场(P<0.05);大型养殖场的PCV2和PCV3病原阳性率均显著高于小型养殖场(P<0.05)。结果表明:安徽省PCVAD防控取得一定成效,但是PCV2仍存在广泛感染,PCV3愈加流行,屠宰场和大型养殖场感染风险高。建议持续做好PCV2免疫工作,加强屠宰场的风险监测及大型养殖场的饲养管理和生物安全管理,严防PCV2和PCV3在养殖和屠宰环节流通传播。

环嗪酮在蓝莓上的残留及其膳食风险评估

为探明环嗪酮在蓝莓上的最终残留量,在我国浙江、吉林、辽宁和北京4地开展了75%环嗪酮水分散粒剂的田间残留实验。采用电喷雾电离正离子模式,建立超高效液相色谱-串联质谱法测定蓝莓中环嗪酮残留量的方法。样品经乙腈涡旋提取、盐包盐析,再用装有十八烷基键合硅胶(C_(18))和乙二胺-N-丙基硅烷材料的净化管净化后测定。考察方法的线性、基质效应、定量限、正确度和精密度(相对标准偏差)。在0.0001~0.01 mg/L范围内,环嗪酮的标准曲线方程的线性关系良好,r>0.9998;基质效应为-7.7%;方法定量限为0.01 mg/kg。在0.01、0.1mg/kg和1.0mg/kg添加量范围内,环嗪酮在蓝莓中平均回收率为87%~91%,相对标准偏差不高于3.7%。4个实验点(浙江、北京、辽宁、吉林)最终残留实验结果显示:环嗪酮在实验点药后90d和100d的蓝莓样品中残留量均低于0.01mg/kg,低于美国、日本和韩国制定的最大残留限量值(分别为0.6、0.2mg/kg和0.05mg/kg)。膳食风险评估结果表明:普通人群环嗪酮的国家估算每日摄入量为0.0022mg,膳食摄入风险的风险熵为0.084%,膳食风险小。因此,建议75%的环嗪酮水分散粒剂在蓝莓园使用时,最高施药剂量为有效成分1800g/hm^(2),施药1次,安全间隔期为90d。

考虑环间接头影响的盾构隧道纵向变形简化解

为反映外荷载下盾构隧道相邻环间张开和错台,提出考虑环间接头影响的盾构隧道纵向变形简化解答。首先,引入纵向梁-弹簧模型模拟盾构隧道纵向受力变形,其中采用Timoshenko短梁考虑隧道环段变形,引入转动和剪切弹簧分别模拟环间接头转动与错台。其次,构建弹性地基上纵向梁-弹簧模型的有限差分方程,以解决环间接头-管环非连续变形求解问题,并推导外荷载下既有盾构隧道的纵向变形公式。最后,建立新建隧道上穿和下穿引起既有盾构隧道的纵向变形解答,并与新建隧道上、下穿越工程案例及现有理论方法对比验证。研究结果表明:所提方法预测的隧道位移与Timoshenko连续梁模型,协同变形模型和实测数据均具有较好的一致性,但所提方法得到的环间错台略低于Timoshenko梁模型和协同变形模型;所提方法可考虑环间接头的影响,得到的隧道位移曲线呈现既不光滑也不连续的特征,其中环段变形以刚体位移为主,而环间接头主要发生转动和错台;而基于现有理论所得盾构隧道纵向位移均为连续曲线,无法反映环间接头的真实转动与错台位移。

不同纤维增韧环氧沥青混合料性能

为探究不同种类纤维(玄武岩纤维、玻璃纤维和聚酯纤维)对环氧沥青混合料抗开裂和耐疲劳性能的提升效果,在混合料配比设计的基础上,采用车辙试验、低温小梁试验、浸水马歇尔试验以及冻融劈裂试验等对其进行路用性能测试。通过冲击试验,探究纤维对环氧沥青混合料的三种增韧效果:在环氧沥青混合料中添加纤维可以不同程度提高其路用性能;低温性能再加入纤维后,提升效果较为明显;添加玄武岩纤维路用性能优于玻璃纤维和聚酯纤维。

两级液环压缩机内流场及外特性

采用数值模拟与试验相结合的方法,以2SY-6两级液环压缩机为研究对象,对多级液环压缩机在不同工况、不同叶轮宽度比下内流场及性能进行对比分析,结果表明:二级叶轮叶片载荷小于一级叶轮,其排气口区域锯齿形气液交界面较一级叶轮更为光滑.一级叶轮吸气口区域回流强度相对于二级叶轮吸气口区域更强,一级叶轮吸气口区域湍动能明显大于二级叶轮.等外径设计的二级叶轮进出口压缩比远小于一级叶轮,二级叶轮的做功能力小于一级叶轮.由于一级叶轮的进出口压缩比较大且均位于效率极值点的右侧,一级叶轮效率随泵的压缩比增大而逐渐下降,而二级叶轮压缩比范围包含极值点,所以其效率先增后减.液环压缩机随着二级叶轮宽度的增大,其吸气能力越强,各个工况下的流量均逐渐增大.低压缩比工况下的效率随k值减小逐渐增大,高压缩比工况下的效率随k值减小先增后减.随首次级叶轮宽度比k值的减小,二级叶轮的压缩比曲线逐渐向上平移,而一级叶轮的压缩比曲线逐渐向下平移.随泵出口压力的增大,首次级叶轮压缩比的比值曲线下降趋于平缓,k值为2.2时两级叶轮压缩比的比值趋于1.1.