Detection of joint capsule changes by differential scanning calorimetry (DSC) in different types of hip disorders to evaluate surgical techniques (a preliminary report)

In this study, paraffin-/ultrasonic-treated diatomite was characterized for use as phase change material (PCM) for thermal energy storage in buildings. The diatomite was treated with ultrasound at various periods of time. The diatomite treated with ultrasound for 60 min (DA-60) was the optimum condition providing the highest surface area without structural degradation. The melting point and latent heat of the paraffin/DA-60 composite PCM were 59 °C and 45.90 J g^?1, respectively. The obtained form-stable PCM had good thermal reliability after 500 cycles of thermal cycling test. The thermal performance of PCM was tested by incorporating the paraffin/DA-60 composite PCM into gypsum board. The results showed that the gypsum board containing the paraffin/DA-60 composite PCM had better thermal energy absorption and release characteristics than those of the control sample. The incorporation of paraffin/DA-60 composite PCM into suitable building materials could thus considerably reduce the energy consumption of cooling system in buildings.     

Core/Shell Structured PCM Nanocapsules Obtained by Resin Fortified Emulsion Process

Phase change material (PCM, octadecane) nanocapsules were successfully prepared by resin fortified emulsion (RFE) polymerization using the alkali soluble resin (ASR) of poly(ethylene‐co‐acrylic acid) (EAA) and poly(styrene‐co‐acrylic acid) (SAA). Stable PCM nanocapsules were obtained by resin fortified emulsion polymerization, which could be attributed to the prevention of Ostwald ripening due to PCM being hydrophobic. Analysis of online FTIR measurements throughout the reaction confirmed that the nanocapsules contained octadecane as a PCM. TEM imaging of the PCM nanocapsules showed spherical and core/shell morphology. The characteristics of PCM nanocapsules can be controlled by process parameters. As a result, the particle size and particle size distribution (i.e., polydispersity index (Dw/Dn)) of the PCM nanocapsules were created by adjusting manufacturing conditions. The PCM nanocapsules exhibited thermal energy storage (～49.8 J/g) and release (～47.9 J/g) behavior.     

茯苓菌丝体多糖的分离及结构分析

由茯苓菌种在培养基中于 2 5℃下培养一周得茯苓菌丝体 .分别用 0 9%NaCl水溶液、热水、0 5mol/LNaOH和 88%甲酸从该茯苓菌丝体中提取出四种多糖 ,编号为PCM1 ,PCM2 ,PCM3和PCM4 .用红外光谱 (IR) ,高效液相色谱 (HPLC) ,气相色谱 (GC)及13 C 核磁共振 ( 13 C NMR)等方法分析了它们的组成和结构 .结果表明 ,PCM1 ,PCM2为酸性杂多糖由D 鼠李糖、D 木糖、D 甘露糖、D 半乳糖、D 葡萄糖及葡萄糖醛酸组成 .PCM3主要为线型 β ( 1→ 3 ) D 葡聚糖 ,其产率占茯苓菌丝体总量的 55 8% .PCM4由D 葡萄糖和葡萄糖醛酸组成 .茯苓菌丝体化学组成和结构基本同于茯苓菌核多糖 ,随提取过程进行葡萄糖含量逐渐增加的变化规律也相同 .     

Improvement of thermal inertia of styrene–ethylene/butylene–styrene (SEBS) polymers by addition of microencapsulated phase change materials (PCMs)

In this work, microencapsulated phase change materials (PCMs) with a melting temperature of 52 °C have been used to improve thermal inertia phenomena on an elastomeric matrix of styrene–ethylene/butylene–styrene (SEBS) material. The amount of PCMs has varied in the 1–10 wt.% and these materials have been processed by conventional injection molding without PCM degradation. Mechanical characterization of SEBS–PCM compounds has been carried out and the obtained results show good maintenance of both resistant and ductile properties for PCM amounts comprised in the 1–5 wt.% range. Scanning electron microscopy (SEM) analysis has revealed good wetting properties of PCM microcapsules with the SEBS matrix which is a key factor to obtain good mechanical performance. The effect of PCM addition on thermal inertia has been evaluated by active infrared thermography (IRT), showing a remarkable effect on thermal regulation of SEBS in the temperature range close to the melting point of the PCM (52 °C). This thermoregulation effect is more accurate as the PCM content increases. Also, cooling curves have been constructed in order to quantify the thermal inertia effect in a cooling process.     

Pericellular matrix plays an active role in retention and cellular uptake of large-sized nanoparticles

As the outmost coating of cells, the pericellular matrix (PCM) involved in various cellular functions has been exploited previously to be able to accumulate 120 nm Au nanoparticles (NPs), adjust their diffusion coefficient similar to that of membrane receptors, and enhance their uptake efficiency. In this study, the interactions between PCM and NPs with different sizes and materials were systematically investigated. We found that PCM can selectively enhance the retention and cellular uptake of NPs with diameters from 50 to 180 nm, but has no enhancement effect for 20 nm NPs. Identical behaviors of PCM was observed for both Au NPs and polystyrene NPs, indicating that this unique phenomenon is more related to the dimensions of the NPs. The study of single-particle tracking of 50–180 nm NPs on the surface of thick PCM cells revealed that PCM actively adjusts the diffusion coefficient of NPs to ～0.1 μm²/s regardless of their sizes. By blocking the receptor-mediated endocytosis (RME) pathway with four different inhibitors, this active role of PCM can be effectively suppressed, further confirming that the trapping and retention of NPs by PCM is an inherent biological function. These findings provided new insights for better understanding of the RME pathway and may have promising NP-based applications for controlled drug delivery and therapy in biomedicine.

Thermal properties of the graphite/n-docosane composite PCM

Graphite/n-docosane composite phase change materials (PCM) were prepared. 4, 10, and 16% graphite were added into n-docosane in order to study the effect of the amount of graphite to the thermal properties of the composite PCM. The structure of the composite PCM was characterized using scanning electron microscopy. The thermal properties of the composite PCM were determined using thermal constant analysis, heat storage/release curve, differential scanning calorimetry, and thermogravimetry analysis. The results revealed that the heat storage/release rate and the thermal conductivity increased with an increase in the amount of graphite, whereas the latent heat of the composite PCM decreased with the increase in the amount of graphite.     

Pericellular matrix enhances retention and cellular uptake of nanoparticles

A hydrated gel-like pericellular matrix (PCM) covers the surface of all eukaryotic cells and plays a key role in many cellular events, but its effect on nanoparticle internalization has not been studied. Here, using cells with various PCM thicknesses and gold nanoparticles as probes, we demonstrate that, rather than being a barrier to all foreign objects, the PCM can entrap and accumulate NPs, restrict and slow down their diffusion, and enhance their cellular uptake efficiency. Moreover, this newly discovered PCM function consumes energy and seems to be an integral part of the receptor-mediated endocytosis process. These findings are important in understanding the delivery mechanisms of nanocarriers for biomedical applications.     

相变蓄热材料研究进展

相变蓄热材料(恒温潜热热能储存材料)是目前最热门的功能材料之一。它在发生相变时储存、放出的热量能够帮助所在系统进行能量的储存,同时可以一定程度上缓解双方在时间、强度及地点上的不匹配程度。相变蓄热材料优点突出,其中包括在使用过程中自身温度变化较小、有很好的稳定性、储热能力较强等。此类材料对环境友好,响应了国家近年来节能环保的政策,同时也可以极大地优化所在系统的运行效率。本文综述了近年来几类相变蓄热材料的种类、特点及国内外学者应对于不同缺陷做出的改进及其应用于行业的研究现状,并对未来的发展进行了探讨与展望。     

Predicting hydration free energies of neutral compounds by a parametrization of the polarizable continuum model

A parametrization of the polarizable continuum model (PCM) is presented having the experimental hydration free energies of 215 neutral molecules as target. The cavitation and dispersion contributions were based on the Tu?on-Silla-Pascual-Ahuir (Tu?on; et al. Chem. Phys. Lett. 1993, 203, 289) and Floris-Tomasi (Floris, F.; Tomasi, J. J. Comput. Chem. 1989, 10, 616) expressions, respectively. Both the polar and nonpolar contributions were evaluated on the same solvent-excluding molecular surface that used unscaled Bondi atomic radii. The parametrization was provided for the HF, Xalpha, LSDA, B3LYP, and mPW1PW91 methods at the 6-31G(d) basis set, and the results are in fair agreement with the experimental data. For the sake of comparison, the PCM(UAHF) and our parametrization (PCM2), both at HF level, have produced DeltaG(PCM(UAHF)) = aDeltaGexp (a = 1.02 +/- 0.02, r = 0.945, sd = 0.987, Ftest = 1778) and DeltaG(PCM2) = aDeltaGexp (a = 0.95 +/- 0.02, r = 0.952, sd = 0.843, Ftest = 2070), respectively. The mean absolute deviations from experimental data were 0.67 and 0.68 kcal/mol for PCM(UAHF) and PCM2, respectively.     

Numerical simulation and parametric analysis of latent heat thermal energy storage system

This paper presents the numerical analysis of the transient performance of the latent heat thermal energy storage unit established on finite difference method. The storage unit consists of a shell and tube arrangement with phase change material (PCM) filled in the shell space and the heat transfer fluid (HTF) flowing in the inner tube. The heat exchange between the HTF, wall and PCM has been investigated by developing a 2-D fully implicit numerical model for the storage module and solving the complete module as a conjugate problem using enthalpy transforming method. A comparative investigation of the total melting time of the PCM has been performed based on natural convection in liquid PCM during the charging process. The novelty of this paper lies in the fact it includes convection in PCM and this investigation includes a detailed parametric study which can be used as a reference to design latent heat storage. The results indicate that natural convection accelerates the melting process by a significant amount of time. In order to optimize the design of the thermal storage unit, parametric study has been accompanied to analyze the influence of various HTF working conditions and geometric dimensions on the total melting time of the PCM. Another important feature considered in this work is the influence of the inner wall of the tube carrying the HTF on the entire melting time of the PCM. An error of around 7.2% is reported when inner wall of the tube is ignored in the analysis.

     

Formation of Pickering emulsion by use of PCM and SiC and application to preparation of hybrid microcapsules with interfacial polycondensation reaction

It was tried to form Pickering emulsion by use of paraffin wax as a phase change material (PCM) and SiC as solid powder and to apply to the preparation of the hybrid microcapsules with the interfacial polycondensation reaction. Pickering emulsion could be formed by stirring PCM and SiC in the continuous water phase. The mean diameter of PCM droplets in the (O/W) emulsion decreased with the added amount of SiC. The SiC weight adhered on the surface of PCM droplets become the maximum in the continuous phase with pH 6.8. The hybrid microcapsules with the shell made of SiC and polyurea resin film could be prepared by using Pickering emulsion. There was a critical adhesion weight of SiC, above which the hybrid microcapsules could not be formed. Thermal conductivity of hybrid microcapsules could be improved as compared with the PCM microcapsules. Copyright © 2015 John Wiley & Sons, Ltd.     

Numerical study of the effects of nanofluids and phase-change materials in photovoltaic thermal (PVT) systems

In this paper, the effects of pure water, SiO₂/water nanofluid, and a phase-change material (PCM) as coolants on the performance of a photovoltaic thermal (PVT) system are numerically investigated. The simulations are performed on two modules of PVT with PCM (PVT/PCM module) and without (PVT module). Parameters including PV surface temperature, thermal, and electrical efficiencies of the systems are studied and compared with each other. Moreover, the results of nanofluid as a working fluid is compared with those obtained using pure water. The results show that in the water-based PVT/PCM, the average PV cell temperature is decreased by 16 °C compared to that of the PVT system. This results in an increase of 8% in the electrical efficiency and 25% in the thermal efficiency. In addition, using nanofluid (SiO₂ with 1 and 3 mass% mass fraction) as a coolant in the PVT/PCM system increases the thermal efficiency by 3.51% and 10.40%, for 1 and 3 mass%, respectively, compared to that of the PVT/PCM with pure water as a coolant. This study shows that increasing the melting temperature of the phase-change material leads to an increase in the thermal efficiency of the PVT/PCM system.

     

Numerical investigation on cooling performance of PCM/cooling plate hybrid system for power battery with variable discharging conditions

To solve the cooling problems of power battery with variable discharging conditions, a hybrid thermal management system combined with phase change materials (PCM) and cooling plate is designed. Moreover, the ANSYS FLUENT is adopted to simulate the three-dimensional model. As a result, the effects of water flow direction and variable discharging conditions are discussed on the maximum temperature and maximum temperature difference inside the battery as well as the liquid fraction of PCM. The numerical results indicate that the maximum temperature is governed by the physical parameters of PCM, whereas the water flow direction in the cooling plate plays a dominant role on the maximum temperature difference. Moreover, the flow direction scheme of case 5 is benefit to reduce the maximum temperature and temperature difference simultaneously. Although the cooling performance of hybrid thermal management system can be deteriorated by increasing the pulse duration and heat flux, the melting of PCM dramatically suppresses the increase in maximum temperature and temperature difference. Considering the limited quality of PCM, enhancing the thermal conductivity of PCM and employing cooling scheme with staggered flow direction are recommendable ways to extend the applicability of the hybrid thermal management system for power battery with complex discharging conditions.

     

Characterization of form-stable phase-change material for solar photovoltaic cooling

Solar PV panel cooling is essential to achieve maximum efficiency of PV modules. Phase-change material (PCM) is one of the prominent options to cool the panel and reduce the temperature, since PCMs have low thermal conductivity. Expanded graphite particles are used to enrich the structure and stability as well as to increase the thermal properties. In the present research work, polyethylene glycol (PEG) 1000 is used as a base material and expanded graphite for inclusive particle. A novel form-stable PEG1000/EG composite PCM mixture is prepared, using impregnation and dispersion method. Expanded graphite and PEG1000/EG sample phase compositions are investigated, using X-ray diffraction technique. No new peak is identified in the composite PCM sample. The surface morphology and structure of EG and PEG1000/EG are investigated, using scanning electron microscopy (SEM). Chemical stability analysis is done by Fourier-transform infrared spectroscopy. Thermal properties of the prepared composite PCMs are analysed by differential scanning calorimetry, thermogravimetric analysis (TGA) and KD2 pro analyser. Results show that addition of EG in various propositions (5%, 10% and 15%) enhances the thermal conductivity of PCM samples from 0.3654 to 1.7866 W mK^?1, while melting point and latent heat of fusion of PCM samples are getting reduced. TGA thermographs are used to investigate the thermal stability of the composite PCM samples. TGA curves show that loss of mass happens above the operating temperature, and it is varied with different mass ratios of EG. Characterization of the prepared composite PCM samples is compared and found that PEG1000-85%/EG-15% is the best form-stable PCM, suitable for cooling the solar PV panel as well as to improve the electrical efficiency coupled with a decrease of temperature in the range of 35 °C to 40 °C.

     

Evolved gas analysis (EGA) of brick clays

Using a system based on non-dispersive infrared (NDIR) detectors, evolved gas analysis (EGA) was able to identify and quantify the principal volatiles produced by heating powdered samples of UK brick clays. From these results, atmospheric emissions likely to result from brick production can be predicted. In addition, EGA results for extruded brick clay test pieces are significantly different from those of powdered samples. Within an extruded brick clay body, evolved gases are contained within a pore system and evolved gas-solid phase reactions also occur. This EGA study provides further evidence on the nature of firing reactions within brick clay bodies. The qualitative and quantitative influence of heating rate — a key process condition in brick manufacture — on gas release is also outlined.Dedicated to Dr. Robert Mackenzie on the occasion of his 75th birthday     

Application of PCM thermal energy storage system to reduce building energy consumption

The building sector is known to make a large contribution to total energy consumption and CO₂ emissions. Phase change materials (PCMs) have been considered for thermal energy storage (TES) in buildings. They can balance out the discrepancies between energy demand and energy supply, which are temporally out of phase. However, traditional PCMs need special latent storage devices or containers to encapsulate the PCM, in order to store and release the latent heat of the PCM. The proper design of TES systems using a PCM requires quantitative information and knowledge about the heat transfer and phase change processes in the PCM. In Korea, radiant floor heating systems, which have traditionally been used in residential buildings, consume approximately 55% of the total residential building energy consumption in heating. This article reviews the development of available latent heat thermal energy storage technologies and discusses PCM application methods for residential building using radiant floor heating systems with the goal of reducing energy consumption.     

Impregnation of a porous material with a PCM on a cotton fabric and the effect of vacuum on thermo-regulating textiles

The purpose of this study was the preparation of a form-stable composite phase change material (PCM) by incorporation of n-nonadecane within the expanded dolomite (ED). In this investigation, two approaches called impregnation treatment with vacuuming and impregnation by magnetic stirrer were used. This method was first proposed for textile thermal protection. In this method, n-nonadecane was applied as the phase change material and ED as the supporting in order to prepare and construct the composite PCM. Composite properties were determined by Fourier transformation infrared spectroscope and scanning electronic microscope (SEM) techniques and the heat transfer measurement and differential scanning calorimeter (DSC) were used to determine the thermal properties of composite on fabrics. Also, moisture transfer properties were measured. The SEM results showed that the n-nonadecane was well absorbed in the porous network of the ED. DSC analysis and heat transfer also indicated that fabric temperature range for the amount of coated PCM depends on its area; further, by adding composite to the fabric surface, thermal transfer could be reduced. The maximum percentages of n-nonadecane within ED in the composite PCM1 and PCM2 were measured to be about 90 and 70 mass%, respectively. Thus, the composite PCM1 can be considered as a form-stable composite change phase materials.