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
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
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 cr...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
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
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
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
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
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 salts...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 salts added on the distribution of lanthanides between two phases were investigated. Two different compositions Ln(H2O)s-2 (TOPO)2(OH)2NO3 (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 Kex and PH1/2 value were calculated and the thermodynamic parameters were obtained from the dependence of Kex on the temperature.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
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
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-contai...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.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
Taking advantage of heat absorbing and releasing capability of phase change material(PCM),Paraffin wax-based concrete was prepared to assess its automatic temperature control performance.The mechanical properties of P...Taking advantage of heat absorbing and releasing capability of phase change material(PCM),Paraffin wax-based concrete was prepared to assess its automatic temperature control performance.The mechanical properties of PCM concrete with eight different Paraffin wax contents were tested by the cube compression test and four-point bending test.The more Paraffin wax incorporated,the greater loss of the compressive strength and bending strength.Based on the mechanical results,four contents of Paraffin wax were chosen for studying PCM concrete's thermal properties,including thermal conductivity,thermal diffusivity,specific heat capacity,thermal expansion coefficient and adiabatic temperature rise.When the Paraffin wax content increases from 10%to 20%,the thermal conductivity and the thermal diffusivity decrease from 7.31 kJ/(m·h·°C)to 7.10 kJ/(m·h·°C)and from 3.03×10−3 m2/h to 2.44×10−3 m2/h,respectively.Meanwhile the specific heat capacity and thermal expansion coefficient rise from 5.38×10−1 kJ/(kg·°C)to 5.76×10−1 kJ/(kg·°C)and from 9.63×10−6/°C to 14.02×10−6/°C,respectively.The adiabatic temperature rise is found to decrease with an increasing Paraffin wax content.Considering both the mechanical and thermal properties,15%of Paraffin wax was elected for the mass concrete model test,and the model test results confirm the effect of Paraffin wax in automatic mass concrete temperature control.展开更多
Researches have shown that Raphia hookeri gum could be used as a binder in pharmaceutical formulations and gums in general have been used as emulsifiers in liquid paraffin emulsion but nothing has been heard of Raphia...Researches have shown that Raphia hookeri gum could be used as a binder in pharmaceutical formulations and gums in general have been used as emulsifiers in liquid paraffin emulsion but nothing has been heard of Raphia hookeri in liquid paraffin emulsion as an emulsifier.This work was aimed at evaluating the emulsifying properties of Raphia gum in liquid paraffin emulsion.Two separate preparations containing different concentrations(1,2,3,5 and 10%w/v)of Raphia gum and acacia gum respectively were prepared.Five liquid paraffin emulsions(200 mL each)were also prepared using 60 mL liquid paraffin as the oil phase and 6 g of the various combinations of Raphia gum and Tween 80 as emulsifier blend at ratio 1:5,1:2,1:1,2:1 and 5:1.The preparations were assessed using density,viscosity and stability after 5 days of storage as evaluation parameters.By increasing the concentration of Raphia and Acacia gum,the density of emulsion formed increased.The ranking of the density was 10%>5%>3%>2%>1%.The viscosity of emulsion increased as the concentration of the gum increased.The viscosity which plays a role in the stability of emulsion increased as the concentration of gum increased.The ranking of viscosity was 10%>5%>3%>2%>1%.The stability of the emulsion was measured by the level of creaming and cracking.Emulsion containing 2%w/v of Raphia gum with a creaming index of 23%was more stable compared to the emulsion containing 3%w/v acacia gum with creaming index of 29.9%.The viscosity and stability of emulsion containing emulsifier blends of Raphia and Tween 80 increased with increase in the concentration of Raphia gum.Emulsion containing 3%w/v Raphia gum with no creaming was more stable than emulsion containing 1%w/v emulsifier blend.Raphia gum is suitable for use at a concentration of 2%w/v as an emulsifier in 50 mL of liquid paraffin emulsion competing alternatively to standard acacia gum for emulsification as against Afzelia africana in our previous research which was suitable for use at a concentration of 3%w/v as an emulsifier in 30%v/v liquid paraffin emulsion.展开更多
BACKGROUND Nucleic acid isolation from formalin-fixed, paraffin-embedded tissue(FFPET)samples is a daily routine in molecular pathology laboratories, but extraction from FFPET is not always easily achieved. Choosing t...BACKGROUND Nucleic acid isolation from formalin-fixed, paraffin-embedded tissue(FFPET)samples is a daily routine in molecular pathology laboratories, but extraction from FFPET is not always easily achieved. Choosing the right extraction technique is key for further examinations.AIM To compare the performance of four commercially available kits used for DNA extraction in routine practice.METHODS DNA isolation was performed on 46 randomly selected formalin-fixed, paraffinembedded(FFPE) colorectal adenocarcinoma(CRC) surgical specimens. Four commercially available extraction kits were used: two for manual DNA extraction(the Pure Link Genomic DNA Mini Kit from Invitrogen and the High Pure FFPE DNA Isolation Kit from Roche) and two for automated DNA extraction(the i Prep Genomic DNA Kit from Invitrogen and the Magna Pure LC DNA Isolation Kit from Roche). The DNA concentration and quality(odds ratio) among the four systems were compared. The results were correlated with the clinicopathological aspects of CRC cases: age, gender, localization, macro-and microscopic features,lymph node metastases, and the lymph node ratio.RESULTS The highest DNA concentration was obtained using the manual kits: 157.24 ±62.99 ng/μL for the Pure Link Genomic DNA Mini Kit and 86.64 ng/μL± 43.84 for the High Pure FFPE DNA Isolation Kit(P < 0.0001). Lower concentrations were obtained with automated systems: 20.39 ± 21.19 ng/μL for the Magna Pure LC DNA Isolation Kit and 8.722 ± 6.408 ng/μL for the i Prep Genomic DNA Kit,with differences between the systems used(P < 0.0001). The comparison between age, gender, tumor localization, pT or pN stage and the lymph node ratio indicated no statistically significant difference in DNA concentration using any of the nucleic acid isolation kits. DNA concentration was influenced by the macroscopic features and grade of differentiation. A higher DNA concentration was obtained for well-differentiated polypoid colorectal adenocarcinomas(CRCs), compared with undifferentiated ulcero-infiltrative carcinomas,irrespective of the kit used.CONCLUSION For research or diagnosis that needs high DNA concentrations, manual methods of DNA isolation should be used. A higher amount of DNA can be obtained from polypoid-type differentiated CRCs. Automated systems confer comfort and a lower amount of DNA that is, however, sufficient for classic polymerase chain reaction(PCR) and real-time quantitative PCR molecular examinations. All four commercially available kits can be successfully used in daily practice.展开更多
Background: Differential diagnosis of follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA) is often difficult since presence or absence of capsular/vascular invasion can not be determined by preope...Background: Differential diagnosis of follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA) is often difficult since presence or absence of capsular/vascular invasion can not be determined by preoperative fine needle aspiration cytology, and may not be judged unanimously on permanent sections even among experienced pathologists. Determination of molecular-genetic factors such as trefoil factor 3 (TFF3) mRNA in the follicular thyroid tumors may be useful aid to improve the accuracy of diagnosis, though it is considered to be unstable and relatively low concentrated genetic substance. Purpose of our study is to investigate expression level of TFF3 mRNA of thyroid follicular tumors using formalin-fixed, paraffin-embedded (FFPE) tissue. Methods: Study population included FFPE sections from 19 FTC cases, 20 FTA cases, 11 adenomatous goiter (G) cases and 12 samples of normal thyroid tissue (N) adjacent to thyroid tumors. RNeasy FFPE kit was used for extraction of total RNA. Purification and concentration values were determined by spectrophotometer. Extracted RNA was used for cDNA synthesis in reverse transcription. Synthesized cDNA subsequently proceeded for relative quantification of TFF3 mRNA by RT-qPCR using TFF3 primers. Glyceroldehyde-3-phosphate dehydrogenase (GAPDH) and hypoxanthin phosphorobosyltransferase1 (HPRT1) were used as control genes. The mean and standard deviation of TFF3 mRNA expression level were analyzed by software Multiplate RQ. Results: Extraction by the FFPE kit yielded high concentration of RNA in all cases. Purification values were 1.8 in average. Concentration values were significantly higher in FTC and FTA relative to G and N tissues, possibly due to high density of thyrocytes in the samples. Relative quantification of TFF3 mRNA expression level showed broad ranges both in FTC and FTA, while the analyses in G and N tissues indicated narrow ranges. Conclusion: FFPE tissues from thyroid follicular tumors can be used for measurement of unstable and low concentrated genetic substances such as TFF3 mRNA. Its diagnostic value yet remains to be determined.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.
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 cr...
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.
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.
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.
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.
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 salts added on the distribution of lanthanides between two phases were investigated. Two different compositions Ln(H2O)s-2 (TOPO)2(OH)2NO3 (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 Kex and PH1/2 value were calculated and the thermodynamic parameters were obtained from the dependence of Kex on the temperature.
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.
基金financially supported by the Natural Science Foundation of Shanghai(Grant 16ZR1408100)the National Natural Science Foundation of China(Grant 91634112 and 21878097)the Open Project of State Key Laboratory of Chemical Engineering(SKL-ChE-16C01)
文摘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.
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.
基金This work is jointly supported by the National Natural Science Foundation of China(Grant Nos.51909223,51902270)the National Science Fund for Distinguished Young Scholars(Grant No.41825015)+2 种基金the Natural Science Basic Research Program of Shaanxi(Grant No.2019JQ-921)the Special research project of the Education Department of Shaanxi Provincial Government(Grant No.19JK0913)the Special Fund for the Launch of Scientific Research in Xijing University(Grant No.XJ18T02).
文摘Taking advantage of heat absorbing and releasing capability of phase change material(PCM),Paraffin wax-based concrete was prepared to assess its automatic temperature control performance.The mechanical properties of PCM concrete with eight different Paraffin wax contents were tested by the cube compression test and four-point bending test.The more Paraffin wax incorporated,the greater loss of the compressive strength and bending strength.Based on the mechanical results,four contents of Paraffin wax were chosen for studying PCM concrete's thermal properties,including thermal conductivity,thermal diffusivity,specific heat capacity,thermal expansion coefficient and adiabatic temperature rise.When the Paraffin wax content increases from 10%to 20%,the thermal conductivity and the thermal diffusivity decrease from 7.31 kJ/(m·h·°C)to 7.10 kJ/(m·h·°C)and from 3.03×10−3 m2/h to 2.44×10−3 m2/h,respectively.Meanwhile the specific heat capacity and thermal expansion coefficient rise from 5.38×10−1 kJ/(kg·°C)to 5.76×10−1 kJ/(kg·°C)and from 9.63×10−6/°C to 14.02×10−6/°C,respectively.The adiabatic temperature rise is found to decrease with an increasing Paraffin wax content.Considering both the mechanical and thermal properties,15%of Paraffin wax was elected for the mass concrete model test,and the model test results confirm the effect of Paraffin wax in automatic mass concrete temperature control.
文摘Researches have shown that Raphia hookeri gum could be used as a binder in pharmaceutical formulations and gums in general have been used as emulsifiers in liquid paraffin emulsion but nothing has been heard of Raphia hookeri in liquid paraffin emulsion as an emulsifier.This work was aimed at evaluating the emulsifying properties of Raphia gum in liquid paraffin emulsion.Two separate preparations containing different concentrations(1,2,3,5 and 10%w/v)of Raphia gum and acacia gum respectively were prepared.Five liquid paraffin emulsions(200 mL each)were also prepared using 60 mL liquid paraffin as the oil phase and 6 g of the various combinations of Raphia gum and Tween 80 as emulsifier blend at ratio 1:5,1:2,1:1,2:1 and 5:1.The preparations were assessed using density,viscosity and stability after 5 days of storage as evaluation parameters.By increasing the concentration of Raphia and Acacia gum,the density of emulsion formed increased.The ranking of the density was 10%>5%>3%>2%>1%.The viscosity of emulsion increased as the concentration of the gum increased.The viscosity which plays a role in the stability of emulsion increased as the concentration of gum increased.The ranking of viscosity was 10%>5%>3%>2%>1%.The stability of the emulsion was measured by the level of creaming and cracking.Emulsion containing 2%w/v of Raphia gum with a creaming index of 23%was more stable compared to the emulsion containing 3%w/v acacia gum with creaming index of 29.9%.The viscosity and stability of emulsion containing emulsifier blends of Raphia and Tween 80 increased with increase in the concentration of Raphia gum.Emulsion containing 3%w/v Raphia gum with no creaming was more stable than emulsion containing 1%w/v emulsifier blend.Raphia gum is suitable for use at a concentration of 2%w/v as an emulsifier in 50 mL of liquid paraffin emulsion competing alternatively to standard acacia gum for emulsification as against Afzelia africana in our previous research which was suitable for use at a concentration of 3%w/v as an emulsifier in 30%v/v liquid paraffin emulsion.
基金the University of Medicine,Pharmacy,Science and Technology Research Grant,No.275/11.01.2017
文摘BACKGROUND Nucleic acid isolation from formalin-fixed, paraffin-embedded tissue(FFPET)samples is a daily routine in molecular pathology laboratories, but extraction from FFPET is not always easily achieved. Choosing the right extraction technique is key for further examinations.AIM To compare the performance of four commercially available kits used for DNA extraction in routine practice.METHODS DNA isolation was performed on 46 randomly selected formalin-fixed, paraffinembedded(FFPE) colorectal adenocarcinoma(CRC) surgical specimens. Four commercially available extraction kits were used: two for manual DNA extraction(the Pure Link Genomic DNA Mini Kit from Invitrogen and the High Pure FFPE DNA Isolation Kit from Roche) and two for automated DNA extraction(the i Prep Genomic DNA Kit from Invitrogen and the Magna Pure LC DNA Isolation Kit from Roche). The DNA concentration and quality(odds ratio) among the four systems were compared. The results were correlated with the clinicopathological aspects of CRC cases: age, gender, localization, macro-and microscopic features,lymph node metastases, and the lymph node ratio.RESULTS The highest DNA concentration was obtained using the manual kits: 157.24 ±62.99 ng/μL for the Pure Link Genomic DNA Mini Kit and 86.64 ng/μL± 43.84 for the High Pure FFPE DNA Isolation Kit(P < 0.0001). Lower concentrations were obtained with automated systems: 20.39 ± 21.19 ng/μL for the Magna Pure LC DNA Isolation Kit and 8.722 ± 6.408 ng/μL for the i Prep Genomic DNA Kit,with differences between the systems used(P < 0.0001). The comparison between age, gender, tumor localization, pT or pN stage and the lymph node ratio indicated no statistically significant difference in DNA concentration using any of the nucleic acid isolation kits. DNA concentration was influenced by the macroscopic features and grade of differentiation. A higher DNA concentration was obtained for well-differentiated polypoid colorectal adenocarcinomas(CRCs), compared with undifferentiated ulcero-infiltrative carcinomas,irrespective of the kit used.CONCLUSION For research or diagnosis that needs high DNA concentrations, manual methods of DNA isolation should be used. A higher amount of DNA can be obtained from polypoid-type differentiated CRCs. Automated systems confer comfort and a lower amount of DNA that is, however, sufficient for classic polymerase chain reaction(PCR) and real-time quantitative PCR molecular examinations. All four commercially available kits can be successfully used in daily practice.
文摘Background: Differential diagnosis of follicular thyroid carcinoma (FTC) from follicular thyroid adenoma (FTA) is often difficult since presence or absence of capsular/vascular invasion can not be determined by preoperative fine needle aspiration cytology, and may not be judged unanimously on permanent sections even among experienced pathologists. Determination of molecular-genetic factors such as trefoil factor 3 (TFF3) mRNA in the follicular thyroid tumors may be useful aid to improve the accuracy of diagnosis, though it is considered to be unstable and relatively low concentrated genetic substance. Purpose of our study is to investigate expression level of TFF3 mRNA of thyroid follicular tumors using formalin-fixed, paraffin-embedded (FFPE) tissue. Methods: Study population included FFPE sections from 19 FTC cases, 20 FTA cases, 11 adenomatous goiter (G) cases and 12 samples of normal thyroid tissue (N) adjacent to thyroid tumors. RNeasy FFPE kit was used for extraction of total RNA. Purification and concentration values were determined by spectrophotometer. Extracted RNA was used for cDNA synthesis in reverse transcription. Synthesized cDNA subsequently proceeded for relative quantification of TFF3 mRNA by RT-qPCR using TFF3 primers. Glyceroldehyde-3-phosphate dehydrogenase (GAPDH) and hypoxanthin phosphorobosyltransferase1 (HPRT1) were used as control genes. The mean and standard deviation of TFF3 mRNA expression level were analyzed by software Multiplate RQ. Results: Extraction by the FFPE kit yielded high concentration of RNA in all cases. Purification values were 1.8 in average. Concentration values were significantly higher in FTC and FTA relative to G and N tissues, possibly due to high density of thyrocytes in the samples. Relative quantification of TFF3 mRNA expression level showed broad ranges both in FTC and FTA, while the analyses in G and N tissues indicated narrow ranges. Conclusion: FFPE tissues from thyroid follicular tumors can be used for measurement of unstable and low concentrated genetic substances such as TFF3 mRNA. Its diagnostic value yet remains to be determined.
