Melting Peak Temperature Research Articles

Development and Performance Evaluation of an Intelligent Sand Control Screen Based on Polyphenylene Sulfide.

Open hole combined with a sand filter pipe is the main development mode of an unconsolidated sandstone horizontal well, which causes problems such as shaft wall collapse, sand filter pipe blockage, and even damage. At present, the polyurethane intelligent sand control screen pipe can effectively solve these problems, but its application scope is limited by the downhole temperature and material strength. Therefore, the high-strength shape memory polyphenylene sulfide (SMPPPS) was synthesized by an indoor experiment, then the shape memory performance was analyzed, and the variation law of pore size with composition and processing technology was obtained. Finally, the performance of the SMPPPS intelligent screen was evaluated. It is found that (1) with the increase of the cross-linking agent content, the melt index and melt peak temperature of SMPPPS decrease rapidly at first and then remain unchanged; the cross-linking agent content is set at 4.5 wt %. (2) The shape memory performance of SMPPPS is good, and the recovery ratio can reach 99.8% at 110 °C in 11.8 min. (3) The relationship between the pore size distribution proportion of SMPPPS and the foaming agent content, pore enhancer content, temperature, and pressure is determined through experiments; the main distribution range of pore size increases with the increase of the foaming agent content and temperature and decreases with the increase of the pore enhancer content and pressure. When the foaming agent content is 0.5 wt %, the pore enhancer concentration is 10 wt %, the molding temperature is 320 °C, the molding pressure is 10 MPa, and the main distribution range of pore size is 80–320 μm. (4) The permeability of recovery SMPPPS with a compression ratio of 300% first increases slightly and then decreases slightly with the increase of flow, with a variation range of 420.5–463 mD; the compressive strength range is 9.5–11.4 MPa; the SMPPPS has good adaptability to downhole fluid; the sand retaining accuracy is higher than that of the screen sand filter pipe, but the blockage is more serious.

Development of Phytosterol Enriched Functional Edible oils: Study of Physical, Chemical, Thermal and Structural Properties

Phytosterol plays a major role in reducing the bad cholesterol in blood resulting in decreasing the chance of cardiovascular and other chronic diseases in human. The objective of this work was to develop a functional edible oil by incorporating phytosterol into different edible oils, such as, sunflower, soybean, rice bran, canola, and coconut oil to enhance their nutritional and functional value. In this work, thermal and structural properties of the functional oils were evaluated using Differential Scanning Calorimeter (DSC), X-Ray Diffraction (XRD) and Confocal Laser Scanning Microscopy (CLSM), respectively. The physicochemical properties like specific gravity, color, refractive index, peroxide value, acid value and antioxidant activity of the functional oils were studied. Specific gravity, acid value and peroxide value of the functional oils increased slightly as compared to the pure oils which are within acceptable range. The antioxidant capacity of the functional oil increased from 28.85 to 98.25% due to the addition of phytosterol. Onset melting, peak melting and offset melting temperature along with the melting enthalpy were evaluated during thermal transition by using DSC. The melting temperature of the functional oils varied according to the presence of saturated and unsaturated fatty acid content. For example, a lower melting point was obtained for oils containing lower saturated fatty acids and vice versa. XRD results showed significant variations in the crystallinity values in functional oils. From the above study taking all the properties into account, functional soybean oil can be considered as the best oil for various food application due to its higher oxidative stability.

Development of nano‐enhanced phase change materials using manganese dioxide nanoparticles obtained through green synthesis

AbstractThe current paper summarizes the development of nano‐enhanced phase change materials (NPCMs) using capric acid (CA) and manganese dioxide (α‐MnO2) nanoparticles. The nanoparticles were obtained by the green synthesis technique using the leaves of Ficus retusa plant. The obtained nanoparticles were used in 1%, 2%, and 3% weight fractions in the nano‐formulations. The field‐emission scanning electron microscopy (FESEM) was employed to confirm the morphological structure and energy‐dispersive X‐ray (EDX) spectroscopy was used for the elemental analysis of the synthesized nanoparticles. The crystallographic studies were done using X‐ray diffraction (XRD) spectroscopy. The Fourier‐transform infrared (FT‐IR) spectroscopy results showed that the insertion of nanoparticles did not disturb the chemical configuration of CA. The differential scanning calorimetry (DSC) analysis revealed that the developed nanocomposites had excellent thermal energy storage capability that lay within the range of 145–164 kJ/kg. Five hundred extended thermal cycles were carried out which showed that the developed PCM had excellent thermal reliability and can be useful for a year‐long application. The variations reported with 1% nano‐formulation was −1.43% to +0.53%, −0.03% to +1.52%, and −6.67% to 9.94% with respect to onset, peak melting temperature, and latent heat of fusion. The thermal gravimetric analysis (TGA) results showed that developed PCMs were stable within the working temperature range. The melting/solidification curve showed faster heat storage and release rates owing to the increased thermal conductivity. These developed PCMs are useful for photovoltaic/thermal and building applications.

Novel probe-based melting curve assays for the characterization of fluoroquinolone resistance in Mycoplasma genitalium.

Background Mycoplasma genitalium infection is a sexually transmitted infection that has rapidly become resistant to mainstay treatments. While individualized treatment approaches have been recommended and adopted for macrolides, individualized therapy for fluoroquinolones has not yet been explored, due to a lack of commercial molecular assays and a lack of confidence in specific mutations associated with resistance. In another recent study, we defined a clear role and diagnostic utility in focusing on the absence of resistance mutations to inform microbial cure with fluoroquinolone antimicrobials.MethodsWe developed two proof-of-concept molecular tests that focus on detection of M. genitalium and characterization of WT parC sequences that are strongly linked to fluoroquinolone susceptibility.ResultsWe screened a total of 227 M. genitalium-positive samples using novel molecular beacon and dual hybridization probe assays. These assays were able to detect M. genitalium and characterize fluoroquinolone susceptibility in 143/227 (63%) samples, based on clear differences in melting peak temperatures. The results of these molecular assays were in 100% agreement with ‘gold standard’ Sanger sequencing. Additionally, WT parC sequences were readily distinguished from M. genitalium samples harbouring parC mutations of known or suspected clinical significance. The ability of the assays to successfully characterize fluoroquinolone susceptibility and resistance was reduced in low M. genitalium load samples.ConclusionsThese proof-of-concept assays have considerable potential to improve individualized treatment approaches and rationalize tests of cure for M. genitalium infection. The ability to initiate individualized treatment in up to two-thirds of cases will enhance antimicrobial stewardship for this challenging pathogen.

Sucrose- and formaldehyde-modified native starches as possible pharmaceutical excipients in tableting

BackgroundStarches have been shown to be important across various disciplines such as the pharmaceutical industries, food industries and also paper industries. Starch is basically a mixture of polymers consisting of α-d-glucose as the monomeric unit. The goal of this study is to modify the native starches which were obtained from Zea mays, Triticumestivum and Oriza sativa through cross-linking (using sucrose and formaldehyde at different concentrations) and also to assess the utilizability of the modified starches as potential excipients [binder] for tableting of paracetamol.ResultsMaize and rice starches cross-linked with 2.5% sucrose gave the least percentage moisture content. The batches cross-linked with 40% formaldehyde showed the highest moisture content. The densities (bulk and tapped) of maize wheat and rice starches showed a reduction with the increasing concentration of the cross-linking agent for sucrose, which is the reverse case for formaldehyde. The different concentrations of sucrose and formaldehyde cross-maize, wheat and rice starches had pH values between 4.50 and 5.52. The onset and end set of the glass transition temperatures were varied for all the starches modified with formaldehyde. The melting peak temperatures obtained indicated that the formaldehyde-modified rice starch had significantly lower melting temperature than those of wheat and maize starches.ConclusionsThis study reveals that various concentrations of sucrose and formaldehyde had some influence on the properties of the native starches and resulted in the production of new starch motifs with improved or new functionalities suitable for use as drug excipients in tableting.

Influence of functionalized carbon flake on phase change characteristics of deionized (DI) water for cool thermal storage system

The current work aims to study the influence of thermal-resistance (R) and the time constant (τ) in phase change properties of carbon flake-based phase change materials (CPCM) experimentally. The CPCMs were prepared using chemically functionalized graphene flake (f-GP) in three various mass fractions (0.25%, 0.50%, and 0.75%) suspended in deionized (DI) water. The phase transition characteristics were recorded using DSC214-polyma with a heat-flow rate of 1 K/min. The remarkable variation in the peak crystallization and melting during charging and discharging processes were recorded with the combined τ -R correction method. The true peak during charging (−12.21 °C) and discharging (3.91 °C) processes is recorded through the correction of time constant for CPCM with 0.75% of f-GP. In addition, the CPCM with 0.75% f-GP has a maximum reduction in melting and freezing time of 36.01% and 27.75%, respectively. The prediction of phase change properties (peak crystallization and melting temperatures) is very important to design a cool thermal energy storage (CTES) system with maximum storage density. The selection of correct operating temperature of the CTES system reduces the energy input to the chiller plant.

Fabrication, Characterization and In Vitro Assessment of Laevistrombus canarium-Derived Hydroxyapatite Particulate-Filled Polymer Composite for Implant Applications.

This paper presents the formulation, characterization, and in vitro studies of polymer composite material impregnated with naturally derived hydroxyapatite (HA) particulates for biomedical implant applications. Laevistrombus canarium (LC) seashells (SS) were collected, washed and cleaned, sun-dried for 24 h, and ground into powder particulates. The SS particulates of different weight percentages (0, 10, 20, 30, 40, 50 wt%)-loaded high-density polyethylene (HDPE) composites were fabricated by compression molding for comparative in vitro assessment. A temperature-controlled compression molding technique was used with the operating pressure of 2 to 3 bars for particulate retention in the HDPE matrix during molding. The HDPE/LC composite was fabricated and characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX), differential scanning calorimetry (DSC), and TGA. Mechanical properties such as tensile, compression, flexural, hardness, and also surface roughness were tested as per ASTM standards. Mass degradation and thermal stability of the HDPE/LC composite were evaluated at different temperatures ranging from 10 to 700 °C using thermogravimetric analysis (TGA). The maximum tensile strength was found to be 27 ± 0.5 MPa for 30 wt% HDPE/LC composite. The thermal energy absorbed during endothermic processes was recorded as 71.24 J/g and the peak melting temperature (Tm) was found to be 128.4 °C for the same 30 wt% of HDPE/LC composite specimen. Excellent cell viability was observed during the in vitro biocompatibility study for EtO-sterilized 30 wt% of HDPE/LC composite specimen, except for a report of mild cytotoxicity in the case of higher concentration (50 µL) of the MG-63 cell line. The results demonstrate the potential of the fabricated composite as a suitable biomaterial for medical implant applications.

Synthesis of confectionery fat from illipé butter stearin and palm mid‐fraction blend via enzymatic interesterification

AbstractCocoa butter equivalent (CBE) was synthesised from blends of illipé butter stearin (IBS) and palm mid‐fraction (PMF) via enzymatic interesterification (EIE). IBS was blended with PMF in three wt ratios (70:30, 60:40 and 50:50) and the EIE reactions were performed at 50°C for 30 min using an sn‐1,3‐specific lipase from Rhizopus oryzae as a catalyst. The triacylglycerol (TAG) compositions, slip melting points (SMP), crystallisation and melting thermograms, solid fat content (SFC) curves, and crystal microstructure of the blends before and after EIE were studied and compared with cocoa butter (CB). After EIE, the contents of POP and StOSt decreased, whereas the POSt content increased in all blends. Blend EIE 60:40 exhibited the POP and StOSt contents that situated within the ranges of POP and StOSt contents of CB. It also showed SMP, melting peak and melting completion temperatures, melting enthalpy and crystal microstructure most similar to CB. Most importantly, its SFC curve completely matched that of CB. Consequently, EIE 60:40 was chosen for further investigation and it was found to be fully compatible with CB and crystallised into the same polymorphic form (β) as CB. Therefore, EIE 60:40 has a high potential for use as a commercial CBE.

Supercritical carbon dioxide extraction, purification, and characterization of wax from sorghum and sorghum by‐products as an alternative natural wax

AbstractThe objective of this work was to obtain high purity natural wax from sorghum and by‐products of sorghum processing (sorghum dried distillers grains with solubles [DDGS] and sorghum bran) using a green process based on supercritical carbon dioxide (SC‐CO2). SC‐CO2 extractions were carried out at varying temperatures (50, 70°C) and pressures (30, 40 MPa) at a CO2 flow rate 1 L/min for 120 min. Significantly higher wax yield (4.9%) from DDGS was obtained by SC‐CO2 at 40 MPa/70°C compared with whole kernel (0.6%) and bran (3.3%) (p < 0.05). The yield of the extracts obtained by SC‐CO2 extraction was higher than that of the conventional hexane extraction for all three sorghum sources. The highest fraction of wax in the SC‐CO2 extracts was obtained from whole kernel extracts (89%), whereas it was 53.3% from the DDGS and 26.8% from the bran at the same extraction conditions. SC‐CO2 and hexane extracts from sorghum whole kernel shared a similar melting peak temperature of 76.3–77.9 and 79.7°C, respectively, while DDGS and bran extracts by SC‐CO2 showed a much lower melting temperature in the range of 50.7–61.9°C, indicating the presence of lower melting point components such as triacylglycerols. However, the melting points of the DDGS and bran extracts after ethanol purification were significantly increased with the observed peak temperature of 80.8 and 82.0°C, respectively. While the wax yield from DDGS and bran was higher than that of whole kernel, the sorghum whole kernel feedstock was found to be a more feasible feedstock to obtain higher purity wax.

Micro/nanoencapsulation of dimethyl adipate with melamine formaldehyde shell as phase change material slurries for cool thermal energy storage

The present study reports the encapsulation of dimethyl adipate into a polymer shell using in-situ polymerisation. Surface morphology, crystal structure, chemical stability, and thermal properties are characterised using various analytical methods and experimentally investigated. The surface morphology has shown excellent sphericity with a mean particle diameter of 900 nm. The measured enthalpy was 80.2 J/g, with the onset and peak melting temperatures are 6.4 °C and 9.6 °C, respectively. The calculated specific heat capacities of encapsulated dimethyl adipate are around 1.7 J/g.K and 2.3 J/g.K for solid and liquid states, respectively. Furthermore, thermal cycling performance was obtained as 95.3% after 100 thermal cycles. These capsules dispersed into the base fluid (deionized double distilled water) in appropriate proportions for the preparation of micro/nanoencapsulated phase change material slurries (MNPCMS). The prepared slurries have shown a marginal increase in viscosity compared to the base fluid. Therefore, the test results signified that the prepared MNPCMS can be considered as a potential candidate for cool thermal energy storage applications.

Preparation of exfoliated graphite nanoplates/thermoplastic polyurethane composites with enhanced dielectric properties

In this work, exfoliated graphite nanoplates (xGNPs)/thermoplastic polyurethane (TPU) composites with enhanced dielectric constant and relatively low dielectric loss factor were prepared by an effective method involving solution blending and water precipitating. The wide-angle X-ray diffraction results proved that the xGNPs had been added into the TPU. Furthermore, the microstructure of the resultant xGNPs (2 wt.%)/TPU composite was investigated by scanning electron microscopy (SEM). The SEM images showed that there were many xGNPs in the TPU elastomer matrix. According to differential scanning calorimetry the melting peak temperature and the crystallization peak temperature of the xGNPs/TPU composites were lower than those of the pure TPU but the melting enthalpy and the crystallization enthalpy of the xGNPs/TPU composites were higher than those of the pure TPU. More importantly, the dielectric constant at 1000 Hz and the thermal conductivity of the xGNPs/TPU composites obviously increased in comparison with those of the pure TPU, especially when the xGNPs content was 2 wt.%.

Red Pepper and Turmeric-Flavored Virgin Olive Oil Oleogels Prepared with Whale Spermaceti Wax.

This study aimed to prepare and evaluate ground red pepper and turmeric added virgin olive oil (VOO) oleogels with whale spermaceti wax (WSW) as organogelator. The concentration of WSW was 8 wt%, and each spice was added at 1 overall wt%. Prepared oleogels were analyzed for main physico-chemical, structural, thermal, rheological properties. Further, aromatics volatile compositions, sensory descriptive analysis and consumer tests were completed. Results indicated that the new oleogels were quite spreadable preparates with acceptable quality indices. The oleogels included β type polymorphs, and showed up to 38℃ of peak melting temperatures. Rheological measurements proved true gel structure stable within applicable frequencies and above 38°C surrounding temperatures. The oleogels were thermo-reversible, and their gel state was recoverable after high shear. Around 25 different aromatic volatile compounds were identified in the two oleogels, most shown to be originating from the VOO, and the spices added. The panel defined and scored the samples with 12 sensory descriptive (hardness, spreadability, liquefaction, sandiness, olive fruit, grassy, waxy, rancid, bitter, hay, cooling and mouth coating) terms. Sensory scores were mostly similar to each other and also within the ranges given in the literature for similar spreadable fat products. Consumer test identified the samples with liked scores (above 4 in 5-max point scale) for appearance, aroma, flavour and overall acceptability. In conclusion, ground spices enriched VOO oleogels with WSW were developed successively to offer consumers spreadable olive oil products to extent consumption patterns with special flavors and health benefits of the spices.

Study of a thermally enhanced mortar incorporating phase change materials for overheating reduction in buildings

The use of thermal energy storage systems incorporating Phase Change Materials (PCM) as passive thermal regulators, in innovative buildings’ applications is an increasing trend and promising strategy for maintaining indoor thermal comfort while promoting buildings’ energy efficiency in a sustainable way. Incorporating PCM into mortars enhances their thermal properties but modifies physical and mechanical characteristics. This paper presents an experimental research on the microstructural, mechanical, and thermal properties of innovative cementitious mortars incorporating two different microencapsulated PCMs, targeted for low thermal mass constructions located in warm climates.The characterization was developed in three steps: microstructural evaluation using scanning electron microscopy; physical and mechanical characterization by workability, density as well as compressive and flexural strength tests; and thermal characterization through enthalpy-temperature curves, determined with differential scanning calorimetry, and the assessment of real case application to evaluate the impact over the thermal behaviour of a lightweight constructive solution with the developed mortars as inner finishing layer using the hot box heat flux metre method at steady-state conditions. Results revealed an expressive decrease in flexural and compressive strength; significant loss of latent heat capacity and variations of onset and peak melting temperatures were observed; good correlation between thermal conductivity and mean specimen temperatures were attained for the lightweight opaque building solution tested with the two different PCMs, for temperatures below and above the phase change transition zone.

A new express method for determining the number of cycles of freezing and thawing poultry meat

Temperature fluctuations cause significant harm to the quality of poultry meat and its food safety, both at various stages of storage and transportation, as well as sales. Repeated repeated defrosting and freezing lead to a violation of the integrity of cells or protein denaturation, which is accompanied by a change in the ratio of the forms of moisture binding to the product. In this regard, there is an urgent task of establishing the facts of thawing and freezing of poultry meat, determining the number of cycles of repeated freezing. This article is devoted to the development of a new express method for determining the number of cycles of freezing – thawing of a broiler at the stages of the life cycle of poultry products. As the number of «freeze-defrost» cycles increases, the peak area of the differential scanning calorimetry curve (DSC) decreases from 206.4 to 192.6 kJ/mol with electric stunning and from 168.6 to 151.5 kJ/mol with gas stunning, the melting peak temperature also decreases from 5.7 to 5.2 oC with electric stunning and from 5.0 to 4.0 oC with gas stunning. The DSC temperature program and recommendations for its use for monitoring broiler processing and storage processes accompanied by phase transformations of water have been developed.

Melting curve analysis to differentiate Rickettsia spp. and Rickettsia felis

Rickettsiosis, caused by Rickettsia species, is one of the old arthropod-borne illness that commonly found in humans and animals. One of the barriers to rickettsiosis control is the intricacy and time-consuming nature of rickettsiosis laboratory diagnosis. This study aimed to establish quantitative real-time PCR targeting the gltA gene for the DNA differentiation of Rickettsia spp. and Ricketsia felis. The collection of cat flea was extracted to acquire the DNA of Rickettsia. Primers were designed based on the analysis of Rickettsia gltA gene sequences. The confirmation of R. felis was performed by sequencing of PCR product. BLAST analysis was done to confirm the closest similarity of the sequences. Results of this study highlighted the melting temperature was reached at 78,5 °C for Rickettsia spp. and 76.5+0.5 °C for Rickettsia felis. The melting peak temperatures were significantly different between Rickettsia spp. and R. felis (p<0.05). The findings of this work are crucial in the development of powerful diagnostic procedures for detecting and distinguishing Rickettsia spp. and R. felis species.

A comparative study of the application-based properties of hot melt adhesives (HMAs) formulated with different waxes

In this study, three chemically similar but morphologically different high melting hydrocarbon waxes having similar DSC peak melting temperatures were analysed, and the influence of their molecular architectures on hot melt adhesive (HMA) performance, was evaluated. Selected waxes included each of the following types: Fischer Tropsch wax (FT), by-product polyethylene wax (BPPE) and first intention polyethylene wax (FIPE). Both, ethylene-co-vinyl acetate (EVA) and metallocene catalysed polyethylene (mPE) based HMAs were formulated. The high chain linearity of FT wax resulted in faster crystallization and faster adhesive set times as well as higher peel adhesion, shear adhesion and IOPP heat resistance temperatures. Wax viscosities were in direct correlation with resultant HMA viscosities. EVA HMAs had longer set times and were more prone to thermal degradation upon prolonged exposure to elevated temperatures and was most pronounced for FIPE wax. Average traction force was dependent on the open time and wax/polymer combination with FT showing a smaller open time window for both EVA and mPE based HMAs.

Characteristic study of modified nano CuO powder-based paraffin composite and its experimental investigation of melting/solidification behavior for mobilized cold thermal storage systems

The low thermal conductivity of Phase Change Materials (PCM) reduces its performance and remains a challenging issue. In the present study, modified nano copper oxide powder (CuO) with various weight percentages is dispersed into paraffin wax to form Nano-PCM composites (NPCM). Transmission Electron Microscopy analysis showed the uniform dispersion of modified CuO and spherical in structure. Diffraction Scanning Calorimeter analysis (DSC) showed a trivial difference in the melting point of PCM and NPCM. The peak melting temperature of PCM was 18.56°C and for NPCM with 1% concentration was 17.14°C. The thermal conductivity of NPCM in solid and liquid states was high when compared to that of pure PCM. The thermal conductivity of NPCM with a 1% concentration is enhanced by 52% in a solid state and 20% in a liquid state. Solidification/Melting experiments conducted at different bath temperatures such as 15°C, 17°C, and 19°C for PCM and NPCM revealed that the solidification period and melting period reduced with an increase in concentrations of modified Nano CuO due to augmented heat transfer rates. The solidification time for NPCM with 1% concentration is reduced by 18.33% for discharging temperature 25°C, and melting time are reduced by 16.6% for charging temperature.

A SUSTAINABILITY APPROACH: INTEGRATION OF A MICROENCAPSULATED PHASE CHANGE MATERIAL TO A RECYCLED PES NONWOVEN FABRIC TO DEVELOP A HEAT STORING RECYCLED MATERIAL

Phase change materials (PCMs) are thermal energy storing materials which are adopted in various industries including textiles. They provide temperature regulation by absorbing the heat from the ambiance or releasing the latent heat that they store. PCMs are widely integrated into textiles in microencapsulated form where the core PCM is covered by the microcapsule shell and protected during phase change. This form also provides a higher thermal conductivity. In this work, a blend of organic coconut oil and n-octadecane were used as phase change material in core, and melamine formaldehyde was used as shell material to develop microencapsulated PCM for heat storage. The microcapsules were produced by using in situ polymerization method. The developed microcapsules (MPCMs) were integrated to a recycled PES (polyester) nonwoven fabric, generated from PET (polyethylene terephthalate) fibres, and manufactured by combing and needle punching technique. The MPCMs were implemented to the fabric by coating method. The core PCM, MPCM, and the coated nonwoven fabric were assessed by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). SEM results indicated that spherical and uniform microcapsules were obtained with a particle size of 3-9 μm. DSC results revealed that MPCM and the MPCM coated nonwoven fabric possessed a remarkable melting enthalpy of 111 J/g and 30.9 J/g, respectively at peak melting temperatures of 28.1°C and 27.4°C.

Physical characterization of the milk chocolate using whey powder

In this study it was found that the complex microstructure of chocolate was modified by the addition of whey into original milk chocolate. A decreasing particle size diameter of the dispersed cocoa fat particles with increasing whey content followed by dynamic light scattering measurements was confirmed. Changes of the chocolate fat crystallinity through disrupting the highly ordered cocoa fat dense crystal aggregates to the less developed ones deformed by the inclusion of whey particles into the complex chocolate mass were simultaneously confirmed. These morphology changes affected the thermal and rheological behaviour of the studied samples by decreasing the melting peak temperature as well as Casson's plastic viscosity with increasing whey content. Furthermore, a gradual decrease of the hardness, thus reflecting the plasticising effect of the whey particles on the complex crystalline structure of the chocolate, was observed. The latter fact was also confirmed by the decreased acoustic emissions during chocolate breakage, thus indicating the change of the fracture process from brittle to more ductile.

Improvement in thermal stability and crystallization mechanism of Sm doped Ge2Sb2Te5 thin films for phase change memory applications

The thin films of (Ge2Sb2Te5)100−xSmx(x = 0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2) (Sm-GST) phase change material have been investigated employing X-ray photoelectron spectroscopy (XPS) to examine the nature of chemical bonding in as-deposited thin films of Sm-GST. The composition of as-deposited thin films of Sm-GST has been also analyzed from the peak area ratios of XPS core-level spectra and the morphology of the thin film has been studied using field emission scanning electron microscopy (FESEM). The powder samples obtained from the as-deposited thin films have been utilized for the non-isothermal differential scanning calorimetry (DSC) measurements at the constant heating rate of 10 K/min. The values of glass transition temperature (Tg), onset crystallization (Tc), peak crystallization temperature (Tp) and melting temperature (Tm) obtained from DSC curves of Sm-GST thin films have been used for the evaluation of thermal stability parameters. The activation energy for crystallization (Ec) and avrami exponent (n) for fcc and hexagonal phase of Sm-GST thin films have been evaluated using Henderson’s method and Matusita’s method. The impact of Sm doping on the thermal stability, glass-forming ability and crystallization activation energy of as-deposited thin films have been examined and its possible influence on the memory device performance has been correlated.