Experimental study on wax deposition of highly paraffinic oil in intermittent gas-oil flow in pipelines

Oil-gas two phase wax deposition is a fairly common and open-ended question in flow assurance of multiphase transportation pipelines.This paper investigated the two main aspects of oil-gas two phase wax deposition layer:apparent thickness and crystal structure characteristics.A typical highly paraffinic oil in Bohai Sea,China,was used as the experimental material to investigate the wax deposition thickness in oil-gas two phase under the influence of different oil temperatures,superficial gas/liquid phase velocities and gas-oil ratios by using multiphase flow loop experimental device.Just as in the classical theory of wax molecular diffusion,it showed that wax deposition thickness of oil-gas two phase increased with increasing oil temperature.Analysis of the impact of different superficial phase velocities found that the actual liquid flow heat transfer and shear stripping was the gas phase dominant mechanisms determining wax deposit thickness.In addition,the crystal structure of the wax deposition layer was characterized with the help of small-angle X-ray scattering(SAXS)for different circumferential positions,flow rates and gas-oil ratios.The bottom deposition layer had a complex crystal structure and high hardness,which were subject to change over flow rate variations.Furthermore,the SAXS results provided evidence that the indirect effect of the actual liquid velocity modified by the gas phase was the main mechanism.Our study of the effect of gas phase on the wax deposition of oil-gas two phase will help shed light onto the mechanism by which this important process occurs.Our findings address a very urgent need in the field of wax deposition of highly paraffinic oil to understand the flow security of oilgas two phase that occurs easily in multiphase field pipelines.

Protective effect of long-chain polyunsaturated fatty acids on hepatorenal syndrome in rats

BACKGROUND Hepatorenal syndrome(HRS)is the most prevalent form of acute kidney injury in cirrhotic patients.It is characterized by reduced renal blood flow and represents the most severe complication in cirrhotic patients with advanced disease.Previous research has indicated that antioxidants can delay the onset of a hyperdynamic circulatory state in cirrhosis and improve renal function in HRS patients.Regular omega-3 supplementation has significantly reduced the risk of liver disease.This supplementation could represent an additional therapy for individuals with HRS.AIM To evaluated the antioxidant effect of omega-3 polyunsaturated fatty acid supplementation on the kidneys of cirrhotic rats.METHODS Secondary biliary cirrhosis was induced in rats by biliary duct ligation(BDL)for 28 d.We used 24 male Wistar rats divided into the following groups:I(control);II(treated with omega-3,1 g/kg of body weight);III(BDL treated with omega-3,1 g/kg of body weight);and IV(BDL without treatment).The animals were killed by overdose of anesthetic;the kidneys were dissected,removed,frozen in liquid nitrogen,and stored in a freezer at-80℃for later analysis.We evaluated oxidative stress,nitric oxide(NO)metabolites,DNA damage by the comet assay,cell viability test,and apoptosis in the kidneys.Data were analyzed by one-way analysis of variance,and means were compared using the Tukey test,with P≤0.05.RESULTS Omega-3 significantly decreased the production of reactive oxygen species(P<0.001)and lipoperoxidation in the kidneys of cirrhotic rats treated with omega-3(P<0.001).The activity of the antioxidant enzymes superoxide dismutase and catalase increased in the BDL+omega-3 group compared to the BDL group(P<0.01).NO production,DNA damage,and caspase-9 cleavage decreased significantly in the omega-3-treated BDL group.There was an increase in mitochondrial electrochemical potential(P<0.001)in BDL treated with omega-3 compared to BDL.No changes in the cell survival index in HRS with omega-3 compared to the control group(P>0.05)were observed.CONCLUSION The study demonstrates that omega-3 can protect cellular integrity and function by increasing antioxidant enzymes,inhibiting the formation of free radicals,and reducing apoptosis.

Paraffin–CaCl_(2)·6H_(2)O dosage effects on the strength and heat transfer characteristics of cemented tailings backfill

The challenge of high temperatures in deep mining remains harmful to the health of workers and their production efficiency The addition of phase change materials (PCMs) to filling slurry and the use of the cold storage function of these materials to reduce downhole temperatures is an effective approach to alleviate the aforementioned problem.Paraffin–CaCl_(2)·6H_(2)O composite PCM was prepared in the laboratory.The composition,phase change latent heat,thermal conductivity,and cemented tailing backfill (CTB) compressive strength of the new material were studied.The heat transfer characteristics and endothermic effect of the PCM were simulated using Fluent software.The results showed the following:(1) The new paraffin–CaCl_(2)·6H_(2)O composite PCM improved the thermal conductivity of native paraffin while avoiding the water solubility of CaCl_(2)·6H_(2)O.(2) The calculation formula of the thermal conductivity of CaCl_(2)·6H_(2)O combined with paraffin was deduced,and the reasons were explained in principle.(3) The“enthalpy–mass scale model”was applied to calculate the phase change latent heat of nonreactive composite PCMs.(4)The addition of the paraffin–CaCl_(2)·6H_(2)O composite PCM reduced the CTB strength but increased its heat absorption capacity.This research can give a theoretical foundation for the use of heat storage backfill in green mines.

Comparison on Adsorptive Separation of n-Paraffins Based on Binderless and Binder-containing Zeolite 5A Pellets

Binderless zeolite is considered to be a potential alternative for binder-containing zeolite in the industrial applications of adsorptive separation process. Synthesized binderless zeolite and commercial binder-containing product were used in adsorptive separation of n-paraffins from a model oil, with their performance compared. It is indicated that the binderless zeolite exhibits by 25%-35% higher in saturated adsorption capacity and by 115%-130% more adsorption amount at the breakthrough point with much shorter length of mass-transfer zone. Adsorptive separation of n-paraffins from naphtha was carried out in a fixed-bed adsorber containing the synthesized binderless zeolite 5 A under the operating conditions covering a feed space velocity of 90 h-1 and an adsorption temperature of 573 K. As compared to original naphtha, the raffinate shows by 34 units more in research octane number and by around 10% more of potential aromatic content, while the desorption oil exhibits by 13.3% more ethylene yield and by 11.7% higher in total olefins yield.

Emerging low-density polyethylene/paraffin wax/aluminum composite as a form-stable phase change thermal interface material

Thermal interface materials(TIMs) play a vital role in the thermal management of electronic devices and can significantly reduce thermal contact resistance(TCR). The TCR between the solid–liquid contact surface is much smaller than that of the solid–solid contact surface, but conventional solid–liquid phase change materials are likely to cause serious leakage. Therefore, this work has prepared a new formstable phase change thermal interface material. Through the melt blending of paraffin wax(PW) and low-density polyethylene(LDPE), the stability is improved and it has an excellent coating effect on PW. The addition of aluminum(Al) powder improves the low thermal conductivity of PW/LDPE, and the addition of 15wt% Al powder improves the thermal conductivity of the internal structure of the matrix by 67%. In addition, the influence of the addition of Al powder on the internal structure, thermal properties, and phase change behavior of the PW/LDPE matrix was systematically studied. The results confirmed that the addition of Al powder improved the thermal conductivity of the material without a significant impact on other properties, and the thermal conductivity increased with the increase of Al addition. Therefore, morphologically stable PW/LDPE/Al is an important development direction for TIMs.

Haplotype analysis of long-chain non-coding RNA NONHSAT102891 promoter polymorphisms and depression in Chinese individuals: A case-control association study

BACKGROUND Our previous study reported that the single-nucleotide polymorphism(SNP)rs155979 GC in the promoter region of long-chain non-coding RNA(lncRNA)NONHSAT102891 affects depression susceptibility in a Chinese population.AIM To explored associations of two SNPs and haplotypes in the lncRNA NONHSAT102891 promoter region with depression susceptibility in Chinese population.METHODS This this case-control association study was approved by the Ethics Committee of Chengdu Medical College(approval number:201815).Patient diagnosis was based on DSM-IV criteria.We selected a total of 480 patients with depression and 329 healthy controls with no history of psychopathology,and performed genotyping of two SNPs by extracting peripheral venous blood samples from the subjects.The function of the two lncRNA NONHSAT102891 promoter G/C and A/T haplotypes was detected by dual-luciferase reporter assays of human embryonic kidney 293T transfected cells.RESULTS Stratified analysis of clinical and genotypic characteristics of our cohort showed that the degree of mild depressive episodes associated with the rs6230 TC/CC genotype increased by 1.59 times[TC/CC vs TT:odds ratio(OR)=1.59,95%confidence interval(CI):1.08-2.35,P=0.019].The haploid analysis revealed linkage disequilibrium between rs3792747 and rs6230,and the double SNP CG haplotype was more common in the control group compared to case group,indicating that this haplotype significantly reduced the risk of depression(C/G vs T/A:OR=0.42,95%CI:0.21-0.83,P=0.01).There was no significant difference in the dual-luciferase reporter activity of the G/C and A/T haplotypes compared with the control group(P>0.05),indicating that the double SNP haplotype has no transcrip-tional activity.CONCLUSION The rs3792747 and rs6230 CG haplotypes of the lncRNA NONHSA T102891 promoter may be related to a reduced risk of depression in the Han Chinese population.

Long-Chain Gemini Surfactant-Assisted Blade Coating Enables Large-Area Carbon-Based Perovskite Solar Modules with Record Performance

Carbon-based perovskite solar cells show great potential owing to their low-cost production and superior stability in ambient air.However,scaling up to high-efficiency carbon-based solar modules hinges on reliable deposition of uniform defect-free perovskite films over large areas,which is an unsettled but urgent issue.In this work,a long-chain gemini surfactant is introduced into perovskite precursor ink to enforce self-assembly into a network structure,considerably enhancing the coverage and smoothness of the perovskite films.The long gemini surfactant plays a distinctively synergistic role in perovskite film construction,crystallization kinetics modulation and defect passivation,leading to a certified record power conversion efficiency of 15.46%with Voc of 1.13 V and Jsc of 22.92 mA cm^(-2)for this type of modules.Importantly,all of the functional layers of the module are printed through a simple and high-speed(300 cm min^(-1))blade coating strategy in ambient atmosphere.These results mark a significant step toward the commercialization of all-printable carbon-based perovskite solar modules.

石蜡/碱改性硅藻土/膨胀石墨复合相变储热材料的制备及性能

通过碱处理,优化了硅藻土(DIA)的孔隙结构,提高了孔隙率,增加了石蜡(paraffin)负载量。通过直接浸渍法制备了新型性状稳定的石蜡/碱改性DIA/膨胀石墨(EG-alDIAP)复合材料,并研究了其结构与性能的关系。结果表明,复合相变材料的石蜡负载量从47.4%提高到了61.1%,进而提高了复合材料的储热性能;向改性DIA中添加膨胀石墨(EG)提高了复合材料的传热能力,添加质量分数10%EG时导热系数提高了113%(从0.276 W·m^(-1)·K^(-1)提高到了0.589 W·m^(-1)·K^(-1))。随着EG含量的升高,复合相变材料的相变潜热有所增加,但化学相容性、稳定性等无明显变化。含10%EG的石蜡/碱改性DIA复合材料具有可靠的储能性能、良好的温度调节性能和蓄放热能力。

用于加热卷烟的石蜡改性二醋酸纤维素降温滤嘴的制备与表征

以二醋酸纤维素滤棒为载体,以食品级石蜡为相变吸热材料,采用浸渍法制备了石蜡/醋纤降温滤棒,研究了石蜡熔点和负载量对加热卷烟主流烟气温度的影响,并采用热重/差热分析仪(TG/DTA)、傅里叶变换红外光谱仪(FT-IR)、差示扫描量热仪(DSC)和场发射扫描电子显微镜(SEM)等技术对石蜡/醋纤滤棒进行了表征。石蜡/醋纤滤棒是通过醋纤滤棒的吸附作用完成复合,在抽吸过程中具有良好的热稳定性,当52~#石蜡乳化液质量分数为60%时,即石蜡负载量为35 mg时,由石蜡/醋纤滤棒组成的三段式降温滤嘴对主流烟气具有显著的降温效果,可将主流烟气温度从68℃降低到42℃。

由石蜡基相变材料和煤渣改良的粉砂土的冻融性能

【目的】针对季节冻土区渠道的衬砌结构因冻融作用而受损的现状,同时为了解决石蜡基相变材料(phase change materials, PCM)的泄露,并满足煤渣的再利用需求,研究石蜡基PCM和煤渣对土体冻融性能的影响。【方法】以粉砂土为研究对象,选取石蜡基PCM和煤渣作为改良剂,制备石蜡基PCM改良土和石蜡基PCM-煤渣改良土;通过冻融循环作用下的体积变化率试验、无侧限抗压强度试验,微观结构及潜热研究土体的体积和无侧限抗压强度的变化。【结果】石蜡基PCM能抑制粉砂土的冻融变形,质量分数为8%时2种改良土的体积变化率最小;随着冻融循环次数的增加,土体的无侧限抗压强度均降低,降低速率先大后小;循环次数相同时,加入煤渣的改良土的无侧限抗压强度均大于未加入煤渣的;冻融循环9次后,石蜡基PCM质量分数为10%的石蜡基PCM改良土的无侧限抗压强度最低;2种改良土的结构比粉砂土更密实、稳定;潜热的吸收或释放延缓了土体冻融过程。【结论】将石蜡基PCM和煤渣共同掺入粉砂土,能控制土体的冻融变形且效果稳定,改善土体的冻融性能,减轻季节冻土区输水渠道衬砌结构的冻害,提高煤渣的利用率。

膨胀石墨基相变储能材料的制备及性能研究

以膨胀石墨作为主导热材料,石蜡作为相变储热材料,通过真空浸渍法制备了膨胀石墨-石蜡复合相变储能材料,研究了石蜡质量分数对复合相变储能材料微观形貌、物相结构及热性能的影响。结果表明,膨胀石墨和石蜡反应后生成的复合相变储能材料主要依靠物理吸附结合,石蜡均匀覆盖在膨胀石墨的表面以及孔隙中,当石蜡质量分数为91%时,复合相变储能材料的密封性和结构致密性最佳,几乎不发生泄露。随着石蜡质量分数的增加,复合相变储能材料的熔点逐渐增大,热分解温度逐渐提高,石蜡质量分数91%的复合相变储能材料相比石蜡质量分数85%的相变材料热分解温度提高了约15℃。随着石蜡质量分数的增大,复合相变储能材料的导热系数和热扩散系数持续降低,密度先降低后增加,比热持续增大。当石蜡质量分数为94%时,复合相变储能材料的导热系数和热扩散系数均为最低值,分别为2.492 W/(m·K)和0.605 mm^(2)/s;当石蜡质量分数为91%时,复合相变储能材料的密度为最小值0.794 g/cm^(3),对应比热为5.462 J/(g·K)。分析可得,石蜡质量分数为91%的复合相变储能材料的综合性能最佳。

一种优化的桑树花芽石蜡切片制作方法

针对常规石蜡切片方法无法获得完整桑树花芽切片的问题,以“无籽大十”品种桑树花芽为供试材料,在常规石蜡切片技术基础上,对石蜡切片样品制作过程中固定、软化、脱水、透明及染色等环节进行了优化。结果表明,使用15%氢氟酸软化后,采用优化后的系列脱水、透明等步骤进行制片,可以使切片连续性、完整性得到明显提高。通过切片显微观察,可见细胞轮廓明显、裂痕较少、结构较完整,染色较清晰,并且对发育后期的花芽效果更为明显。优化后的制样流程解决了常规制片出现浸蜡不彻底、组织变脆、蜡带不连续、内部结构不完整等一系列问题。该研究可以从解剖学上为桑树花芽发育形态和花芽分化机制研究提供技术参考。

围绕FFPE样本特性的DNA纯化纳米磁珠优化

目的 探讨围绕福尔马林固定石蜡包埋(formalin fixed paraffin embedded, FFPE)样本特性获取更高质量/得率的纳米磁珠核酸提取方案,改进分子病理技术。方法 合成4大类15个小类的备选磁珠,以FFPE样本为中心,筛选高质量/得率磁珠。模拟常规组织、粗针穿刺(肝脏)、纤维支气管镜样本(肺),装管相同张数连片。采用筛选的最佳磁珠与市场出售的常见磁珠试剂提取核酸,横向对比纯化总量、片段大小等质量参数。应用PCR和Sanger验证核酸的下游应用。结果 以FFPE样本DNA为中心筛选自制纳米磁珠,获得最佳性能纳米磁珠总回收率为58.5%±1.58%,5种市售商品化磁珠和3种国产磁珠总回收率为18.68%~40.71%。相同组织量(连片)提取的DNA总量,在模拟常规组织、粗针穿刺和纤维支气管镜样本核酸得率比市售试剂盒提高39.49%~181.72%(P<0.05)。模拟纤维支气管镜样本1张(4μm)总量可达100 ng以上、5张总量可达400 ng以上。结论 以FFPE样本DNA为中心筛选的DNA纯化纳米磁珠,与商品化磁珠相比有较大提升,为临床分子病理检测的质量保证、自动化检测和项目拓展提供空间。

2010年以来国内外石蜡市场分析及展望

近些年欧美市场合成蜡和其他替代产品的发展,压缩了石蜡的消费增长空间。2020年新冠病毒疫情导致全球石蜡需求下降,消费规模退回到2015年的水平。2020—2025年全球石蜡需求将在低基数上稳定增长,但随着合成蜡和环境友好型包装物的使用增加,全球石蜡需求增长空间有限。中国是世界上重要的石蜡生产和出口国,石蜡及其制品的国外市场消纳度已达到70%左右。未来中国石蜡消费量将稳中趋升,预计2025年消费量在90万吨左右;生产企业继续减少,但总生产能力相对稳定。延伸石蜡产业链,提高石蜡制品附加值,做大国内市场,降低对国外市场的依赖程度,是中国石蜡市场未来的发展方向。

气相色谱-串联质谱法测定皮革中的短链氯化石蜡

建立了GC-MS/MS测定皮革中短链氯化石蜡(SCCPs)的方法,采用正己烷对样品进行提取,再用GC-MS/MS测定,外标法定量。结果表明:该方法在SCCPs质量浓度为5~50 mg/L范围内线性良好,线性相关系数为0.998,方法检出限为2.58 mg/kg,定量限为8.95 mg/kg,在低、中、高浓度水平的加标试验中,回收率在90.1%~108.9%,精密度为2.29%~6.22%。该方法具有较低的检出限、较好的精密度和准确度,可用于皮革中短链氯化石蜡的检测。

含强化肋的PCM相变储热与传热特性数值研究

为了有效提升PCM相变储热器的性能,本文采用多种金属翅片对相变过程进行强化,并采用焓-多孔介质模型对相变储热过程进行了数值模拟,分析了不同金属材料和不同基体孔隙率对相变储热及传热特性的影响.研究结果表明,采用金属泡沫强化翅片能够增强导热和对流效应,优化流场对流涡分布,储热器相变储热时间大大缩短,耗时仅为无翅片工况的16.8%;采用铜金属泡沫翅片的储能效率略优于铝金属泡沫翅片,储热时间缩短3.47%;强化翅片孔隙率对储热性能影响较弱,孔隙率为0.4时最优,孔隙率为0.6时次之,孔隙率为0.8时最差.

制样方法对菊花花蕾激光显微切割样品RNA提取质量的影响

[目的]研究不同固定剂及切片制样方式对菊花花蕾激光显微切割样品RNA提取质量的影响。[方法]以丙酮和乙醇冰醋酸2种试剂固定菊花花蕾,采用石蜡和冰冻切片2种方式制作样本,显微切割并收集最外两轮小花原基,提取RNA后比较提取质量。[结果]石蜡和经梯度蔗糖保护的冰冻切片均能很好地保存花蕾组织形态,就石蜡切片而言,乙醇冰醋酸固定组织切割样品的RNA降解明显低于丙酮固定样品;而2种固定剂的冰冻切片切割样品RNA提取质量无明显差异。与石蜡切片相比,冰冻切片显微切割样品RNA质量更高。切割时收集管盖加入RNA提取缓冲液可明显缓解RNA降解。显微切割的不同品种菊花花原基与花发育有关的基因表达水平存在差异,表明切割获得的材料可用于下一步研究。[结论]植物组织经乙醇冰醋酸固定、梯度蔗糖保护后冰冻切片进行显微切割效果较佳,可富集特异组织或细胞并从中获得较高质量的RNA。

二甲苯、正庚烷和正丁醇对脂肪组织透明效果的比较研究

为了找到安全、高效、可替代二甲苯的脂肪组织石蜡切片透明剂,试验采集2月龄健康民猪背部脂肪组织,经固定、脱水后,分别用二甲苯、正庚烷、正丁醇处理不同时间(二甲苯处理1 h,正庚烷处理1 h、2 h、3 h、4 h,正丁醇处理1 h、2 h、3 h、4 h、10 h)进行透明,观察透明效果,然后进行石蜡包埋和切片;选取3种透明剂将脂肪组织完全透明用时最短的石蜡切片,经脱蜡和水化处理后用苏木精染液和伊红染液进行H.E.染色,探究3种透明剂对脂肪组织形态结构的影响;并采用免疫组织化学技术检测过氧化物酶体增殖物激活受体γ(peroxisome proliferators-activated receptor γ,PPARγ)的表达情况,探究3种透明剂是否会影响蛋白质的表达和定位。结果表明:二甲苯处理1 h、正庚烷处理2 h后脂肪组织可完全透明,而正丁醇处理10 h后脂肪组织才完全透明;正庚烷、正丁醇作为透明剂制备的脂肪组织石蜡切片细胞形态清晰、结构完整、着色好,与二甲苯作为透明剂的效果相似;在3种透明剂制备的脂肪组织石蜡切片中,PPARγ均清晰且准确地表达在脂肪细胞的细胞核中。说明正庚烷和正丁醇对脂肪组织的透明效果与二甲苯相似,但正庚烷透明速度较快,正丁醇透明速度很慢,因此实际应用中推荐使用正庚烷作为二甲苯的替代物。

不同温度条件下相变石蜡力学性能分析

对3种不同相变温度的石蜡材料(PCM-28、PCM-18和PCM-10)在不同温度下的基本力学性能参数进行了系统的压缩实验,计算出对应的弹性模量和泊松比。结果表明:PCM-18和PCM-10的抗压强度随温度的降低而有所提高,但PCM-28的抗压强度随温度的降低反而呈现出下降趋势。在单轴压缩条件下PCM-28和PCM-18的应力-应变曲线主要经历了压实阶段、弹性变形阶段、裂纹扩展阶段和裂纹后破坏阶段4个明显阶段,最终表现为脆性破坏。PCM-10在经历压实阶段和弹性变形阶段后进入塑性阶段,曲线发展近似水平,且整个过程无明显裂纹出现。

原油直接催化裂解UPC工艺过程模拟与反应参数多目标优化

原油直接催化裂解技术可以实现从原油到三烯(乙烯、丙烯、丁烯)、三苯(苯、甲苯、二甲苯)的一步跨越,对我国炼化行业的转型升级具有重要意义。以全馏分石蜡基中原原油(159~780℃)为原料,采用混合馏分结构与分子组成集总建模策略,对原油直接催化裂解制烯烃(UPC)反应过程进行建模与工艺参数校准,并基于工业试验数据验证了其准确性。以多产烯烃、控制焦炭生成为目的,利用NSGA-Ⅲ多目标优化算法对模型进行了优化,得到优化后的操作参数。采用优化后的操作参数,即在第一段预热闪蒸温度为194.32℃、第二段预热闪蒸温度为228.16℃、第一段提升管反应器出口温度为615.73℃、第二段提升管反应器出口温度为622.59℃的条件下,UPC工艺得到的乙烯和丙烯收率之和为53.367%,焦炭收率为8.311%。此外,由于现行税费体系燃料型工艺路线税收贡献明显高于化工型工艺路线,UPC工艺参数优化后,烯烃收率大幅度提升,燃料油收率大幅度下降,原油生产总值降低44.30元t。