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 storag...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.展开更多
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 mu...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.展开更多
Objective:The morphology analysis of whole-mount mouse embryos was observed using an improved paraffin section technique.Methods:Mouse embryos of varying embryonic ages were collected and whole-mount embryo paraffin s...Objective:The morphology analysis of whole-mount mouse embryos was observed using an improved paraffin section technique.Methods:Mouse embryos of varying embryonic ages were collected and whole-mount embryo paraffin sections were prepared using PFA-intravenously injected fixation,prolonged dehydration,and paraffin embedding.Hematoxylin and eosin(H&E)staining and immunohistochemical staining were employed to evaluate the quality of sections,with different tissues being observed labeled by CD34.Results:Following a series of tissue processing and staining procedures,the structure of the whole-mount mouse embryo was well-preserved,and the staining was clear and easily distinguishable.Embryos of different embryonic ages were treated differently,yet the quality of tissue processing remained highly consistent.Conclusion:Tissue processing and staining have been significantly improved,allowing for the easy acquisition of whole-mount mouse embryos of different ages through simplified methods of tissue fixation and dehydration duration.The staining results are clear and stable,providing technical support for the study of mouse embryo development.展开更多
The composite phase change material(PCM) consisting of phase change paraffin(PCP) and polymethyl methacrylate(PMMA) was prepared as a novel type of shape-stabilized PCM for building energy conservation through the met...The composite phase change material(PCM) consisting of phase change paraffin(PCP) and polymethyl methacrylate(PMMA) was prepared as a novel type of shape-stabilized PCM for building energy conservation through the method of bulk polymerization. The chemical structure, morphology, phase change temperature and enthalpy, and mechanical properties of the composite PCM were studied to evaluate the encapsulation effect of PMMA on PCP and determine the optimal composition proportion. FTIR and SEM results revealed that PCP was physically immobilized in the PMMA so that its leakage from the composite was prevented. Based on the thermo-physical and mechanical properties investigations, the optimal mass fraction of PCP in the composite was determined as 70%. The phase change temperature of the composite was close to that of PCP, and its latent heat was equivalent to the calculated value according to the mass fraction of PCP in the composite. For estimating the usability in practical engineering, thermal stability, reliability and temperature regulation performance of the composite were also researched by TG analysis, thermal cycling treatments and heating-cooling test. The results indicated that PCP/PMMA composite PCM behaved good thermal stability depending on the PMMA protection and its latent heat degraded little after 500 thermal cycling. Temperature regulation performance of the composite before and after thermal cycling was both noticeable due to its latent heat absorption and release in the temperature variation processes. The PCP/PMMA phase change plate was fabricated and applied as thermal insulator in miniature concrete box to estimate its temperature regulation effect under the simulated environmental condition. It can be concluded that this kind of PCP/PMMA shape-stabilized PCM with the advantages of no leakage, suitable phase change temperature and enthalpy, good thermal stability and reliability, and effective temperature regulation performance have much potential for thermal energy storage in building energy conservation.展开更多
Paraffin deposition is a severe global problem during crude oil production and transportation.To inhibit the formation of paraffin deposits,the commonly used methods are mechanical cleaning,coating the pipe to provide...Paraffin deposition is a severe global problem during crude oil production and transportation.To inhibit the formation of paraffin deposits,the commonly used methods are mechanical cleaning,coating the pipe to provide a smooth surface and reduce paraffin adhesion,electric heating,ultrasonic and microbial treatments,the use of paraffin inhibitors,etc.Pipeline coatings not only have the advantages of simple preparation and broad applications,but also maintain a long-term efficient and stable effect.In recent years,important progress has been made in research on pipe coatings for mitigating and preventing paraffin deposition.Several novel superhydrophilic organogel coatings with low surface energy were successfully prepared by bionic design.This paper reviews different types of coatings for inhibiting wax deposition in the petroleum industry.The research prospects and directions of this rapidly developing field are also briefly discussed.展开更多
Ultra-high molecular weight polyethylene (UHMWPE) with a microporous structure was prepared via thermally induced phase separation (TIPS).Liquid paraffin (LP) was used as a diluent in the preparation of microporous UH...Ultra-high molecular weight polyethylene (UHMWPE) with a microporous structure was prepared via thermally induced phase separation (TIPS).Liquid paraffin (LP) was used as a diluent in the preparation of microporous UHMWPE. Small angle laser light scattering (SALLS) and differential scanning calorimetry (DSC) were used to determine the phase separation temperatures,i.e.the cloud points and the dynamic crystallization temperatures,respectively.It was found that the cloudI points were coincident with the cryst...展开更多
Chimonanthus praecox is an important ornamental plant and cut flower material in China.It blooms in the freezing winter and its flower emits charming fragrance.However,in different region the flowering time is variabl...Chimonanthus praecox is an important ornamental plant and cut flower material in China.It blooms in the freezing winter and its flower emits charming fragrance.However,in different region the flowering time is variable.In order to understand the flowering mechanism of Ch.praecox in the winter,we studied the flower bud differentiation in Spring City-Kunming using paraffin sectioning method in the present study.Meanwhile we compared the differentiation process difference from different regions.It was found that the temperature is the key factor for its flower bud differentiation and blossom of Ch.praecox.In the process of bud differentiation,the temperature 20℃was the optimum for inducing changes from vegetative axillary buds to reproductive buds and subsequent morphological differentiation in Ch.praecox.Furthermore in the first three differentiation periods—tepal primordial stage,staminal primordial stage and pistil primordial stage,Kunming took the shortest time to finish the process due to very rapid temperature rise to 20℃,whereas,in Zhengzhou the time for these differentiations was the longest,which may be caused by the slow temperature rise.After May,the high temperature stress forced the flower buds into the first long dormant period in all regions except Kunming.In Kunming,the average temperature was only 20–25℃,so the flower bud continued to differentiate.In all regions,Kunming is the first to complete whole flower bud differentiation even on the early August,and started the second dormancy very early but very long.In the other regions,the plants went through a shorter dormancy and the low temperature broke the dormancy rapidly.Contrarily the plants of Kunming spent a longer period for the low temperature.Thus,the low temperature less than 10℃is a key factor to breaking the second dormancy.Surely the regular effects of temperature on flower bud differentiation and blossom is very helpful for florescence regulation of Ch.praecox.展开更多
Pollution of petroleum hydrocarbons, in particular oil spills, has attracted much attention in the past and recent decades. Oil spills influence natural microbial community, and physical and chemical properties of the...Pollution of petroleum hydrocarbons, in particular oil spills, has attracted much attention in the past and recent decades. Oil spills influence natural microbial community, and physical and chemical properties of the affected sites. The biodegradation of hydrocarbons by microorganisms is one of the primary ways by which oil spill is eliminated from contaminated sites. One such spill was that of the Russian tanker the Nakhodka that spilled heavy oil into the Sea of Japan on January 2, 1997. The impact of the Nakhodka oil spill resulted in a viscous sticky fluid fouling the shores and affected natural ecosystems. This paper describes the weathering of hydrocarbon-degrading bacteria (genus Pseudomonas) and crystallized organic compounds from the Nakhodka oil spill-polluted seashores after nine years. The Nakhodka oil has hardened and formed crust of crystalline paraffin wax as shown by XRD analysis (0.422, 0.377, and 0.250 nm d-spacing) in association with graphite and calcite after 9 years of bioremediation. Anaerobic reverse side of the oil crust contained numerous coccus typed bacteria associated with halite. The finding of hydrocarbon-degrading bacteria and paraffin wax in the oil crust may have a significant effect on the weathering processes of the Nakhodka oil spill during the 9- year bioremediation.展开更多
To improve the tribological behavior of biodiesel soot(BDS) in liquid paraffin(LP), the order of biodiesel soot was increased through thermally oxidized treatment at 500 ℃, and the oil solubility was then improved th...To improve the tribological behavior of biodiesel soot(BDS) in liquid paraffin(LP), the order of biodiesel soot was increased through thermally oxidized treatment at 500 ℃, and the oil solubility was then improved through a modification using oleylamine(OLA). The BDS and thermally oxidized oleylamine-modified BDS(T-BDS-OLA)were characterized through various methods including the use of TG, FETEM, Raman spectroscopy, FTIR, and a zeta potentiometer. The tribological properties and mechanisms of the BDS before and after the thermally oxidized treatment modification were investigated using a ball-on-disc reciprocating tribometer, FESEM, 3 D laser-scanning microscopy, and Raman spectroscopy. The results showed that T-BDS-OLA has a higher degree of order than the BDS, with an onion-like microstructure. BDS and T-BDS-OLA can both improve the antifriction and antiwear properties of LP at a soot content of 0.1%-0.4%, while T-BDS-OLA in LP shows better antifriction and antiwear properties than BDS. The tribological mechanisms can be attributed to both types of soot acting as spacing and roll bearing between the friction surfaces. In addition, the exfoliated graphitic sheets from T-BDS-OLA can form a carbon lubrication layer providing easy sliding.展开更多
A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material(CPCM) made by paraffin wax and silic...A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material(CPCM) made by paraffin wax and silicon was adopted to facilitate heat transfer. Moreover, high resistance or even insulation of CPCM is capable of preventing short circuits between the cells. The heat transfer mechanism of CPCMs was determined under a scanning electron microscope. A thermogravimetric analyzer was employed to determine the thermal stability. A diff erential scanning calorimeter was used to explore the thermophysical properties of the composite samples. By comparing the results of the experiment, it was reported that under the silicon carbide content of 5%, the parameters were better than others. The phase-change enthalpy of CPCM was 199.4 J/g, the leakage rate of liquid was 4.6%, and the melting point was 53.6℃. To verify the practicality of CPCM, a three-dimensional layered battery pack model was built in the COMSOL Multiphysics software. By simulating the thermal runaway inside the battery packs of various materials, it was reported that the addition of CPCM significantly narrowed the temperature range of the battery pack from 300–370 to 303–304 K. Therefore, CPCM can eff ectively increase the rate of heat transfer to prevent the chain of thermal runaway reactions. It also enables the battery pack to run at a stable temperature.展开更多
Background: Constipation is one of the most common problems in the pediatric age group. In the vast majority, chronic constipation is idiopathic or functional. In addition to education and behavioral changes, disimpac...Background: Constipation is one of the most common problems in the pediatric age group. In the vast majority, chronic constipation is idiopathic or functional. In addition to education and behavioral changes, disimpaction and maintenance treatment with medications are the main pillars of successful outcome. The medications are variably effective and have potential side effects. Objectives: The current clinical trial was designed to evaluate clinical efficacy of polyethylene glycol (PEG) 3350 and liquid paraffin in chronic functional constipation. Besides, subjects were followed carefully for the side effects. Material and Methods: This study was involved 110 children suffering from chronic functional constipation. They were placed into two different groups, randomly. Each group was treated with PEG 3350 or liquid paraffin. The clinical efficacy and side effects were monitored. Results: After disimpaction with bisacodyl suppositories or combined with Mineral oil enemas in hard fecal impaction, maintenance therapy with PEG 3350 or liquid paraffin was started. The treatment duration and efficacies were not different between the two groups. Furthermore, serious adverse drug reaction was not observed. The family history of constipation and presence of incontinence were two worse prognostic factors. Conclusion: No difference was observed between PEG 3350 and liquid paraffin in chronic functional constipation in children in terms of their efficacies. They are safe and effective medications in this age group.展开更多
The extraction behavior of Ln(III) (Ln=Nd, Sm, Tb and Yb) with trioctylphosphine oxide (TOPO) in molten paraffin wax has been studied. The effect of pH, TOPO concentration, medium, stirring time and the amount of sail...The extraction behavior of Ln(III) (Ln=Nd, Sm, Tb and Yb) with trioctylphosphine oxide (TOPO) in molten paraffin wax has been studied. The effect of pH, TOPO concentration, medium, stirring time and the amount of sails added on the distribution of lanthanides between two phases were investigated. Two different compositions Ln(H2O)(t-2) (TOPO)(2)(OH)(2)NO3 (Ln=Nd and Sm) and Ln(H2O)(s-1) (TOPO)(2)(OH)(NO3)(2) (Ln=Tb and Yb) were determined by slope analysis method. The equilibrium extraction constant K-ex and pH(1/2) value were calculated and the thermodynamic parameters were obtained from the dependence of K-ex on the temperature.展开更多
The paraffin wax was used as an organic solvent for 1 phenyl 3 methyl 4 benzoyl 5 pyrazolone (PMBP) and trioctylphousphine oxide (TOPO) in the extraction of rare earth ions (La 3+ , Pr 3+ , Eu 3+ , ...The paraffin wax was used as an organic solvent for 1 phenyl 3 methyl 4 benzoyl 5 pyrazolone (PMBP) and trioctylphousphine oxide (TOPO) in the extraction of rare earth ions (La 3+ , Pr 3+ , Eu 3+ , Yb 3+ and Ho 3+ ) at 70℃. The composition of the extracted specices were given as RE(PMBP) 3(TOPO) 2 by means of slope analysis. The variation of the synergistic extraction equilibrium constant ( K sex ) was studied at 55℃~70℃. The thermodynamic data obtained showed that the synergistic extraction of rare earth ions by PMBP and TOPO in molten paraffin wax is exothermic and the extracted complexes were formed by TOPO bonding to the outer sphere hydration.展开更多
Two microcapsules with different paraffin phase changes were prepared using styrene-divinylbenzene copolymer and melamine resin as the capsule wall and paraffin(with a melting point of 50°C)as the capsule core.Th...Two microcapsules with different paraffin phase changes were prepared using styrene-divinylbenzene copolymer and melamine resin as the capsule wall and paraffin(with a melting point of 50°C)as the capsule core.The microcapsules were directly added to the hydroxyl terminated polybutadiene(HTPB)-polyurethane elastomer system to fabricate the polyurethane elastomer composites.The thermodynamic stability and mechanical properties of the material were then studied.The results show that the thermal stability of the polyurethane elastomer does not decrease after adding paraffin phase change microcapsules,and the thermal stability of the polyurethane elastomer with melamine resin as the wall increases.Tensile strength increased from 367 kPa to 797 kPa,and compression strength increased from 245.9 N to 344.7 N.In addition,capsule walls comprised different monomers/paraffin microcapsules of the copolymer of styrene and divinylbenzene.The optimal mechanical property was obtained at a monomer/paraffin ratio of 1:1.The compression strength increased and the tensile strength decreased.The tensile strength of the microcapsule with melamine resin capsule wall and the compression strength of the microcapsule with polystyrene capsule wall were considerably improved.展开更多
Paraffin/γ-Al2O3 composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of γ-Al2O3.In the composite materials,paraffin was used as a phase change material(PCM)for t...Paraffin/γ-Al2O3 composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of γ-Al2O3.In the composite materials,paraffin was used as a phase change material(PCM)for thermal energy storage,and γ-Al2O3 acted as supporting materials.Characterizations were conducted to evaluate the energy storage performance of the composites,and differential scanning calorimeter results showed that the PCM-3 composite has melting latent heat of 112.9 kJ/kg with a melting temperature of 62.9 ℃.Due to strong capillary force and surface tension between paraffin and γ-Al2O3,the leakage of melted paraffin from the composites can be effectively prevented.Therefore,the paraffin/γ-Al2O3 composites have a good thermal stability and can be used repeatedly.展开更多
[Objective] The purpose was to introduce a preparation method for paraffin section of Bemisia tabaci, so as to lay the foundation for the studies on changes of organizational structure of B. tabaci. [ Method] The tech...[Objective] The purpose was to introduce a preparation method for paraffin section of Bemisia tabaci, so as to lay the foundation for the studies on changes of organizational structure of B. tabaci. [ Method] The technique of paraffin section and the method of H-E staining were adopted to study the organizational structure of B. tabaci. The slices were examined and photographed under fluorescence microscope. [ Result] The coloring of H-E staining cells was good. Under 400 x conditions, the fat body, compound eyes, nucleus and muscle of B. tabaci were clear. [ Conclusion] The production method for paraffin section of B. tabaci was reliable, and the quality of slices was high.展开更多
In process of crude oil production and transportation, wax and other solid deposition issues have a significant impact on oilfield production. Solid precipitation not only reduces the production efficiency and increas...In process of crude oil production and transportation, wax and other solid deposition issues have a significant impact on oilfield production. Solid precipitation not only reduces the production efficiency and increases the cost of production. Therefore, there is a need to study the rate of paraffin wax deposition and cloud point temperature in order to guide the oil field control the paraffin wax deposition. In this paper, we use the Flory theory of polymer solution to correct the liquid activity coefficients, and regular solution theory to correct for the non ideality of the solid mixture, and we consider the impact of isoparaffin. Finally, thermodynamic model is established. The actual example calculation shows that the forecast results of this model are more accurate.展开更多
Aiming at the paraffin-deposition problem of a beam well, the automatic paraffin-controlling device is designed by making use of ratchet-pallet mechanism, cam mechanism and modern designing method. The device has four...Aiming at the paraffin-deposition problem of a beam well, the automatic paraffin-controlling device is designed by making use of ratchet-pallet mechanism, cam mechanism and modern designing method. The device has four main functions: paraffin-controlling, paraffin removal, centralizing the pumping rod, and improving the safety of well tubing. This device integrates the advantages of the paraffin control, such as strong magnetic paraffin controlling and mechanical paraffin-cutting. Theoretical analysis shows that this device has fine working reliability. It turns out to be a new device which can solve the paraffin-deposition problem of a beam well economically and efficiently.展开更多
The isomerization of light paraffin over HZSM-5-Ni-Mo-F synthetic zeolite catalysts was studied, and the effects of reaction conditions on the isomerization were investigated. The results show that the optimum reactio...The isomerization of light paraffin over HZSM-5-Ni-Mo-F synthetic zeolite catalysts was studied, and the effects of reaction conditions on the isomerization were investigated. The results show that the optimum reaction condition can be obtained to enhance the research octane number (RON) of product and the liquid yield. The optimum experimental condition is: HZSM-5 catalyst with 1.5wt% of Ni, 2wt% of Mo and 0.4wt% of F, at a temperature of 345℃ and a reaction mass hourly space velocity (MHSV) of 0.2 h-1. The isomerization reaction of light paraffin from Tarim refinery was studied and the research octane number (RON) of gasoline product could be enhanced by 20 units under the condition of nonhydrogenization and optimum experimental status.展开更多
基金financial support provided by the National Natural Science Foundation of China (No. 52174106)the Key Technology Research and Development Program (No. 2022YFC2905102)。
文摘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.
基金supported by the National Natural Science Foundation of China, China (No. 51874047)the Key Science and Technology Project of Changsha City, China (No. kq2102005)+1 种基金the Special Fund for the Construction of Innovative Province in Hunan Province, China (No. 2020RC3038)the Changsha City Fund for Distinguished and Innovative Young Scholars, China (No. kq1802007)。
文摘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.
基金the funding of Department of Education of Guangdong Province,China(Grant No.2020KTSCX036Grant No.2023A1515010544)Health Commission of Guangdong Province(A2023342).
文摘Objective:The morphology analysis of whole-mount mouse embryos was observed using an improved paraffin section technique.Methods:Mouse embryos of varying embryonic ages were collected and whole-mount embryo paraffin sections were prepared using PFA-intravenously injected fixation,prolonged dehydration,and paraffin embedding.Hematoxylin and eosin(H&E)staining and immunohistochemical staining were employed to evaluate the quality of sections,with different tissues being observed labeled by CD34.Results:Following a series of tissue processing and staining procedures,the structure of the whole-mount mouse embryo was well-preserved,and the staining was clear and easily distinguishable.Embryos of different embryonic ages were treated differently,yet the quality of tissue processing remained highly consistent.Conclusion:Tissue processing and staining have been significantly improved,allowing for the easy acquisition of whole-mount mouse embryos of different ages through simplified methods of tissue fixation and dehydration duration.The staining results are clear and stable,providing technical support for the study of mouse embryo development.
基金Funded by National Natural Science Foundation of China(No.51308275)Natural Science Foundation of Liaoning Province(No.SY2016004)Science Foundation for Young Scientists of Liaoning Educational Committee(No.JQL201915403).
文摘The composite phase change material(PCM) consisting of phase change paraffin(PCP) and polymethyl methacrylate(PMMA) was prepared as a novel type of shape-stabilized PCM for building energy conservation through the method of bulk polymerization. The chemical structure, morphology, phase change temperature and enthalpy, and mechanical properties of the composite PCM were studied to evaluate the encapsulation effect of PMMA on PCP and determine the optimal composition proportion. FTIR and SEM results revealed that PCP was physically immobilized in the PMMA so that its leakage from the composite was prevented. Based on the thermo-physical and mechanical properties investigations, the optimal mass fraction of PCP in the composite was determined as 70%. The phase change temperature of the composite was close to that of PCP, and its latent heat was equivalent to the calculated value according to the mass fraction of PCP in the composite. For estimating the usability in practical engineering, thermal stability, reliability and temperature regulation performance of the composite were also researched by TG analysis, thermal cycling treatments and heating-cooling test. The results indicated that PCP/PMMA composite PCM behaved good thermal stability depending on the PMMA protection and its latent heat degraded little after 500 thermal cycling. Temperature regulation performance of the composite before and after thermal cycling was both noticeable due to its latent heat absorption and release in the temperature variation processes. The PCP/PMMA phase change plate was fabricated and applied as thermal insulator in miniature concrete box to estimate its temperature regulation effect under the simulated environmental condition. It can be concluded that this kind of PCP/PMMA shape-stabilized PCM with the advantages of no leakage, suitable phase change temperature and enthalpy, good thermal stability and reliability, and effective temperature regulation performance have much potential for thermal energy storage in building energy conservation.
文摘Paraffin deposition is a severe global problem during crude oil production and transportation.To inhibit the formation of paraffin deposits,the commonly used methods are mechanical cleaning,coating the pipe to provide a smooth surface and reduce paraffin adhesion,electric heating,ultrasonic and microbial treatments,the use of paraffin inhibitors,etc.Pipeline coatings not only have the advantages of simple preparation and broad applications,but also maintain a long-term efficient and stable effect.In recent years,important progress has been made in research on pipe coatings for mitigating and preventing paraffin deposition.Several novel superhydrophilic organogel coatings with low surface energy were successfully prepared by bionic design.This paper reviews different types of coatings for inhibiting wax deposition in the petroleum industry.The research prospects and directions of this rapidly developing field are also briefly discussed.
基金supported by Special Funds for Major State Basic Research Projects,China (No.2003CB615705).
文摘Ultra-high molecular weight polyethylene (UHMWPE) with a microporous structure was prepared via thermally induced phase separation (TIPS).Liquid paraffin (LP) was used as a diluent in the preparation of microporous UHMWPE. Small angle laser light scattering (SALLS) and differential scanning calorimetry (DSC) were used to determine the phase separation temperatures,i.e.the cloud points and the dynamic crystallization temperatures,respectively.It was found that the cloudI points were coincident with the cryst...
基金funded by Talents Introduction Plan of Yunnan Province-"High-End Foreign Experts"Program(Grant No.000019)。
文摘Chimonanthus praecox is an important ornamental plant and cut flower material in China.It blooms in the freezing winter and its flower emits charming fragrance.However,in different region the flowering time is variable.In order to understand the flowering mechanism of Ch.praecox in the winter,we studied the flower bud differentiation in Spring City-Kunming using paraffin sectioning method in the present study.Meanwhile we compared the differentiation process difference from different regions.It was found that the temperature is the key factor for its flower bud differentiation and blossom of Ch.praecox.In the process of bud differentiation,the temperature 20℃was the optimum for inducing changes from vegetative axillary buds to reproductive buds and subsequent morphological differentiation in Ch.praecox.Furthermore in the first three differentiation periods—tepal primordial stage,staminal primordial stage and pistil primordial stage,Kunming took the shortest time to finish the process due to very rapid temperature rise to 20℃,whereas,in Zhengzhou the time for these differentiations was the longest,which may be caused by the slow temperature rise.After May,the high temperature stress forced the flower buds into the first long dormant period in all regions except Kunming.In Kunming,the average temperature was only 20–25℃,so the flower bud continued to differentiate.In all regions,Kunming is the first to complete whole flower bud differentiation even on the early August,and started the second dormancy very early but very long.In the other regions,the plants went through a shorter dormancy and the low temperature broke the dormancy rapidly.Contrarily the plants of Kunming spent a longer period for the low temperature.Thus,the low temperature less than 10℃is a key factor to breaking the second dormancy.Surely the regular effects of temperature on flower bud differentiation and blossom is very helpful for florescence regulation of Ch.praecox.
文摘Pollution of petroleum hydrocarbons, in particular oil spills, has attracted much attention in the past and recent decades. Oil spills influence natural microbial community, and physical and chemical properties of the affected sites. The biodegradation of hydrocarbons by microorganisms is one of the primary ways by which oil spill is eliminated from contaminated sites. One such spill was that of the Russian tanker the Nakhodka that spilled heavy oil into the Sea of Japan on January 2, 1997. The impact of the Nakhodka oil spill resulted in a viscous sticky fluid fouling the shores and affected natural ecosystems. This paper describes the weathering of hydrocarbon-degrading bacteria (genus Pseudomonas) and crystallized organic compounds from the Nakhodka oil spill-polluted seashores after nine years. The Nakhodka oil has hardened and formed crust of crystalline paraffin wax as shown by XRD analysis (0.422, 0.377, and 0.250 nm d-spacing) in association with graphite and calcite after 9 years of bioremediation. Anaerobic reverse side of the oil crust contained numerous coccus typed bacteria associated with halite. The finding of hydrocarbon-degrading bacteria and paraffin wax in the oil crust may have a significant effect on the weathering processes of the Nakhodka oil spill during the 9- year bioremediation.
基金supported by the National Natural Science Foundation of China (Grant No. 51675153)the Major Science and Technology Special Project in Anhui (Grant No. 17030901084)
文摘To improve the tribological behavior of biodiesel soot(BDS) in liquid paraffin(LP), the order of biodiesel soot was increased through thermally oxidized treatment at 500 ℃, and the oil solubility was then improved through a modification using oleylamine(OLA). The BDS and thermally oxidized oleylamine-modified BDS(T-BDS-OLA)were characterized through various methods including the use of TG, FETEM, Raman spectroscopy, FTIR, and a zeta potentiometer. The tribological properties and mechanisms of the BDS before and after the thermally oxidized treatment modification were investigated using a ball-on-disc reciprocating tribometer, FESEM, 3 D laser-scanning microscopy, and Raman spectroscopy. The results showed that T-BDS-OLA has a higher degree of order than the BDS, with an onion-like microstructure. BDS and T-BDS-OLA can both improve the antifriction and antiwear properties of LP at a soot content of 0.1%-0.4%, while T-BDS-OLA in LP shows better antifriction and antiwear properties than BDS. The tribological mechanisms can be attributed to both types of soot acting as spacing and roll bearing between the friction surfaces. In addition, the exfoliated graphitic sheets from T-BDS-OLA can form a carbon lubrication layer providing easy sliding.
基金supported by the National Key Research and Development Projects(No.2018YFC0808600)。
文摘A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material(CPCM) made by paraffin wax and silicon was adopted to facilitate heat transfer. Moreover, high resistance or even insulation of CPCM is capable of preventing short circuits between the cells. The heat transfer mechanism of CPCMs was determined under a scanning electron microscope. A thermogravimetric analyzer was employed to determine the thermal stability. A diff erential scanning calorimeter was used to explore the thermophysical properties of the composite samples. By comparing the results of the experiment, it was reported that under the silicon carbide content of 5%, the parameters were better than others. The phase-change enthalpy of CPCM was 199.4 J/g, the leakage rate of liquid was 4.6%, and the melting point was 53.6℃. To verify the practicality of CPCM, a three-dimensional layered battery pack model was built in the COMSOL Multiphysics software. By simulating the thermal runaway inside the battery packs of various materials, it was reported that the addition of CPCM significantly narrowed the temperature range of the battery pack from 300–370 to 303–304 K. Therefore, CPCM can eff ectively increase the rate of heat transfer to prevent the chain of thermal runaway reactions. It also enables the battery pack to run at a stable temperature.
文摘Background: Constipation is one of the most common problems in the pediatric age group. In the vast majority, chronic constipation is idiopathic or functional. In addition to education and behavioral changes, disimpaction and maintenance treatment with medications are the main pillars of successful outcome. The medications are variably effective and have potential side effects. Objectives: The current clinical trial was designed to evaluate clinical efficacy of polyethylene glycol (PEG) 3350 and liquid paraffin in chronic functional constipation. Besides, subjects were followed carefully for the side effects. Material and Methods: This study was involved 110 children suffering from chronic functional constipation. They were placed into two different groups, randomly. Each group was treated with PEG 3350 or liquid paraffin. The clinical efficacy and side effects were monitored. Results: After disimpaction with bisacodyl suppositories or combined with Mineral oil enemas in hard fecal impaction, maintenance therapy with PEG 3350 or liquid paraffin was started. The treatment duration and efficacies were not different between the two groups. Furthermore, serious adverse drug reaction was not observed. The family history of constipation and presence of incontinence were two worse prognostic factors. Conclusion: No difference was observed between PEG 3350 and liquid paraffin in chronic functional constipation in children in terms of their efficacies. They are safe and effective medications in this age group.
基金the Natural Science Foundation of Gansu Province, China.
文摘The extraction behavior of Ln(III) (Ln=Nd, Sm, Tb and Yb) with trioctylphosphine oxide (TOPO) in molten paraffin wax has been studied. The effect of pH, TOPO concentration, medium, stirring time and the amount of sails added on the distribution of lanthanides between two phases were investigated. Two different compositions Ln(H2O)(t-2) (TOPO)(2)(OH)(2)NO3 (Ln=Nd and Sm) and Ln(H2O)(s-1) (TOPO)(2)(OH)(NO3)(2) (Ln=Tb and Yb) were determined by slope analysis method. The equilibrium extraction constant K-ex and pH(1/2) value were calculated and the thermodynamic parameters were obtained from the dependence of K-ex on the temperature.
文摘The paraffin wax was used as an organic solvent for 1 phenyl 3 methyl 4 benzoyl 5 pyrazolone (PMBP) and trioctylphousphine oxide (TOPO) in the extraction of rare earth ions (La 3+ , Pr 3+ , Eu 3+ , Yb 3+ and Ho 3+ ) at 70℃. The composition of the extracted specices were given as RE(PMBP) 3(TOPO) 2 by means of slope analysis. The variation of the synergistic extraction equilibrium constant ( K sex ) was studied at 55℃~70℃. The thermodynamic data obtained showed that the synergistic extraction of rare earth ions by PMBP and TOPO in molten paraffin wax is exothermic and the extracted complexes were formed by TOPO bonding to the outer sphere hydration.
基金The work is financially supported by the National Natural Science Foundation of China(No.:b030301,a020601)the Foundation project for basic discipline research of Inner Mongolia Agricultural University(jc2017005)the research start project for high level talent of Inner Mongolia Agricultural University(ndgcc2016-17).
文摘Two microcapsules with different paraffin phase changes were prepared using styrene-divinylbenzene copolymer and melamine resin as the capsule wall and paraffin(with a melting point of 50°C)as the capsule core.The microcapsules were directly added to the hydroxyl terminated polybutadiene(HTPB)-polyurethane elastomer system to fabricate the polyurethane elastomer composites.The thermodynamic stability and mechanical properties of the material were then studied.The results show that the thermal stability of the polyurethane elastomer does not decrease after adding paraffin phase change microcapsules,and the thermal stability of the polyurethane elastomer with melamine resin as the wall increases.Tensile strength increased from 367 kPa to 797 kPa,and compression strength increased from 245.9 N to 344.7 N.In addition,capsule walls comprised different monomers/paraffin microcapsules of the copolymer of styrene and divinylbenzene.The optimal mechanical property was obtained at a monomer/paraffin ratio of 1:1.The compression strength increased and the tensile strength decreased.The tensile strength of the microcapsule with melamine resin capsule wall and the compression strength of the microcapsule with polystyrene capsule wall were considerably improved.
文摘Paraffin/γ-Al2O3 composites as phase change energy storage materials were prepared by absorbing paraffin in porous network of γ-Al2O3.In the composite materials,paraffin was used as a phase change material(PCM)for thermal energy storage,and γ-Al2O3 acted as supporting materials.Characterizations were conducted to evaluate the energy storage performance of the composites,and differential scanning calorimeter results showed that the PCM-3 composite has melting latent heat of 112.9 kJ/kg with a melting temperature of 62.9 ℃.Due to strong capillary force and surface tension between paraffin and γ-Al2O3,the leakage of melted paraffin from the composites can be effectively prevented.Therefore,the paraffin/γ-Al2O3 composites have a good thermal stability and can be used repeatedly.
基金Supported by National Natural Science Foundation of China ( NSFC )( 30970438,31071708)
文摘[Objective] The purpose was to introduce a preparation method for paraffin section of Bemisia tabaci, so as to lay the foundation for the studies on changes of organizational structure of B. tabaci. [ Method] The technique of paraffin section and the method of H-E staining were adopted to study the organizational structure of B. tabaci. The slices were examined and photographed under fluorescence microscope. [ Result] The coloring of H-E staining cells was good. Under 400 x conditions, the fat body, compound eyes, nucleus and muscle of B. tabaci were clear. [ Conclusion] The production method for paraffin section of B. tabaci was reliable, and the quality of slices was high.
文摘In process of crude oil production and transportation, wax and other solid deposition issues have a significant impact on oilfield production. Solid precipitation not only reduces the production efficiency and increases the cost of production. Therefore, there is a need to study the rate of paraffin wax deposition and cloud point temperature in order to guide the oil field control the paraffin wax deposition. In this paper, we use the Flory theory of polymer solution to correct the liquid activity coefficients, and regular solution theory to correct for the non ideality of the solid mixture, and we consider the impact of isoparaffin. Finally, thermodynamic model is established. The actual example calculation shows that the forecast results of this model are more accurate.
文摘Aiming at the paraffin-deposition problem of a beam well, the automatic paraffin-controlling device is designed by making use of ratchet-pallet mechanism, cam mechanism and modern designing method. The device has four main functions: paraffin-controlling, paraffin removal, centralizing the pumping rod, and improving the safety of well tubing. This device integrates the advantages of the paraffin control, such as strong magnetic paraffin controlling and mechanical paraffin-cutting. Theoretical analysis shows that this device has fine working reliability. It turns out to be a new device which can solve the paraffin-deposition problem of a beam well economically and efficiently.
文摘The isomerization of light paraffin over HZSM-5-Ni-Mo-F synthetic zeolite catalysts was studied, and the effects of reaction conditions on the isomerization were investigated. The results show that the optimum reaction condition can be obtained to enhance the research octane number (RON) of product and the liquid yield. The optimum experimental condition is: HZSM-5 catalyst with 1.5wt% of Ni, 2wt% of Mo and 0.4wt% of F, at a temperature of 345℃ and a reaction mass hourly space velocity (MHSV) of 0.2 h-1. The isomerization reaction of light paraffin from Tarim refinery was studied and the research octane number (RON) of gasoline product could be enhanced by 20 units under the condition of nonhydrogenization and optimum experimental status.