Melt Homogenization Research Articles

4-Hexylresorcinol Loaded Solid Lipid Nanoparticles for Enhancing Anticancer Activity.

Cancer is one of the most significant threats to human health. Following surgical excision, chemotherapy is an effective strategy against remaining cancer cells. 4-hexylresorcinol (4-HR) has anti-cancer properties and exhibits hydrophobicity-induced aggregation in the blood that has trouble with targeted tumor delivery and cellular uptake of the drug. The purpose of this study is to encapsulate 4-HR into solid lipid nanoparticles (SLNs) to enhance its anti-cancer effect by avoiding aggregation and facilitating cellular uptake. 4-HR SLNs were prepared via hot melt homogenization with sonication. SLN characteristics were assessed by analyzing particle size, zeta potential, and drug release. Cytotoxicity, as an indicator of the anti-cancer effect, was evaluated against HeLa (cervical cancer in humans), A549 (lung cancer in humans), and CT-26 (colon carcinoma in mice) cell lines. Particle size ranged from 169.4 to 644.8 nm, and zeta potential ranged from -19.8 to -40.3 mV, which are conducive to cellular uptake. Entrapment efficiency (EE) of 4-HR was found to be 75.0-96.5%. The cytotoxicity of 4-HR-loaded SLNs demonstrated enhanced anti-cancer effects compared to pure 4-HR. The enhancement of anti-cancer effects depended on reduced particle size based on cellular uptake, the EE, and the cell type. These findings imply that 4-HR-loaded SLN is a promising strategy for chemotherapy in cancer treatment.

Coastal and deep-sea biodegradation of polyhydroxyalkanoate microbeads

Microbeads find widespread usage in personal care items and cosmetics, serving as exfoliants or scrubbing agents. Their micro-scale size poses challenges in effective drainage capture and given their origin from non-biodegradable oil-based plastics, this contributes substantially to marine pollution. In this study, microbeads were prepared by a simple yet scalable melt homogenization method using four types of polyhydroxyalkanoates (PHA), namely poly[(R)-3-hydroxybutyrate] (P(3HB)), poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (P(3HB-co-3HV)), poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyhexanoate] (P(3HB-co-3HHx)) and poly[(R)-3-hydroxybutyrate-co-(R)-4-hydroxyvalerate] (P(3HB-co-4HB)). Microbeads with different surface smoothness, compressive strength (6.2–13.3 MPa) and diameter (from 1 ~ 150 μm) could be produced. The microbeads were subjected to a comprehensive degradation analysis using three techniques: enzymatic, Biochemical Oxygen Demand (BOD) evaluations, and in situ degradation tests in the deep-sea off Misaki Port in the northern Pacific Ocean (depth of 757 m). Qualitatively, results from enzymatic and in situ degradation demonstrated significant degradation within one week and five months, respectively. Quantitatively, BOD findings indicated that all PHA microbeads degraded similarly to cellulose (~ 85% biodegradability in 25 days). In conclusion, PHA microbeads from this study exhibit promising potential as alternatives to conventional non-biodegradable microbeads.

Effect of powder and process parameters on in-situ alloying of nitinol during laser powder bed fusion

Powder characteristics such as flow energy, bulk density, compressibility, morphology, particle size distribution (PSD) and laser energy absorbtivity have a significant impact on the Laser Bed Powder Fusion (L-PBF) process. The impact of powder characteristics on in-situ nickel-titanium alloy formation within the L-PBF process is not well understood. In this work, the characteristics of nickel, titanium and two elemental blends of nickel-titanium powder were compared with those of a pre-alloyed nitinol powder. L-PBF solidification tracks were generated using selected powders and characterised for resulting track dimensions and chemical homogeneity. This study demonstrates that the melt homogenisation time and the size of titanium particles relative to nickel particles are critical factors for successful in-situ alloying of nitinol within the L-PBF process. The variation in elemental composition within solidification track cross sections, as measured by EDX point spectra, was found to increase significantly for laser scanning speeds of 400 mm/s and above. Furthermore, the elemental composition inhomogeneity with increasing laser scan speed was found to be significantly more pronounced for a nickel-titanium powder blend of spherical particles with average titanium particle size of 48 μm compared to an otherwise similar blend with an average titanium particle size of 32 μm. There was no significant difference recorded between solidification track widths of in-situ alloyed blends compared to pre-alloyed blends, indicating that optimal hatch spacing for in-situ alloying is likely to be similar to that required for pre-alloyed powders.

Microstructural Evolution and Mechanical Properties of Y Added CoCrFeNi High-entropy Alloys Produced by Arc-melting

The CoCrFeNi high entropy alloy (HEA) with face-centered cubic (FCC) crystal structure exhibits excellent ductility values even at cryogenic temperatures. However, since this HEA is relatively weak in strength, it may not meet the requirements of industrial applications in terms of strength-ductility trade-off. Therefore, the systematic addition of yttrium (Y) into CoCrFeNi HEA was investigated in the present study to increase the strength by solid solution and second phase strengthening. The HEAs were produced by vacuum arc melting, suction casting, and subsequent homogenization at 1150 °C for 24 h. The structural development of the HEAs was investigated by using the X-ray diffraction (XRD) technique revealing the formation of a solid solution phase and Ni3Y-type hexagonal structure (HS) second phase. The corresponding microstructure of the HEAs was examined under a scanning electron microscope (SEM) revealing the transformation of the microstructure from elongated grains to nearly equiaxed grains with the increase of Y content from 2 at. % to 4 at. %. The mechanical properties of the HEAs were investigated by using hardness and compression tests. The results exhibited a dramatic increase in the hardness from 143 (±2) HV to 335 (±7) HV and in the yield strength from 130 MPa to 1025 MPa with 4 at. % Y addition. Our study has revealed that the addition of rare earth Y element results in further development in the strength of the CoCrFeNi for potential engineering applications.

Effect of melt homogenization on the structure and properties of zirconium-rich basalt fibers

The slow dissolution process of zirconium oxide (ZrO2) limits the efficient and energy-saving production of zirconium-rich basalt fibers with excellent alkali resistance for fiber-reinforced concrete. Therefore, it is necessary to investigate the optimum homogenization conditions to produce high-performance zirconium-rich basalt fibers. In this study, quenched zirconium-rich glasses and zirconium-rich fibers with the addition of 7 wt% ZrO2 at different homogenization temperatures and time were prepared. The quenched melt structure was characterized by XRD and FTIR, and followed information about the melt structure obtained by Gaussian curve fitting of the FTIR spectra. The results indicated that obvious ZrO2 crystals appeared in the melts and fibers with homogenization temperature below 1500 °C and time below 4 h. The degree of polymerization of zirconium-rich basalt melt was found to increase with increasing homogenization temperature and time. Meanwhile, the tensile strength and production stability of zirconium-rich fibers increased with increasing the degree of polymerization. The optimum homogenization temperature and time for zirconium-rich basalt fibers were concluded to be 1580 °C and 10 h, and the corresponding tensile strength is 1799 MPa and 1761 MPa, respectively. By diffusion experiment of ZrO2 in basalt melt with altered major component content, it was found that the Ca, Mg, Na, and Fe significantly facilitated the melting of ZrO2 into basalt melt by XRD and EDS. It was mainly attributed to the charge-compensating effect of metal cations on the [ZrO6] octahedra, which promoted the homogenization of ZrO2 in basalt melt.

Multiphysics modeling and experimental validation of heat and mass transfer for the vacuum induction melting process

Vacuum induction melting is crucial in casting nickel-based superalloy components, ensuring excellent properties for aero-engine applications. Precise melting temperatures are vital for achieving optimal metallurgical quality before casting. Hence, a multiphysics numerical model is developed to simulate the induction melting process for the Inconel 718 superalloy. The proposed holistic model integrates magnetic fields, induced currents, and heat and momentum transfer phenomena in a single coupled model. A moving mesh approach reproduces the magneto-hydrodynamic behavior of the free surface, simulating the oscillations of the melt. The stabilized deformed surface profile is correlated with experimental measurements, reporting a proper correlation. Then, the flow field and recirculation effect are modeled with a Low Reynolds Number turbulence approach and coupled with the melt convective heat transfer, developing a complete magneto-thermo-hydrodynamic model. In a laboratory-scale vacuum induction melting furnace, transient melting operation variables are characterized and introduced to the numerical model to compute the temperature evolution. An accurate reproduction of the transient melt temperature variations is reported with a relative error of less than 5%. The influence of the crucible thermal insulating capacity is assessed, emissivity dependence evaluated, and melt homogenization is reported at different process stages. This comprehensive numerical and experimental approach offers valuable insights for enhancing vacuum induction melting for Ni-based superalloys.

Solid Lipid Nanoparticles Containing Dopamine and Grape Seed Extract: Freeze-Drying with Cryoprotection as a Formulation Strategy to Achieve Nasal Powders

(1) Background: DA-Gelucire® 50/13-based solid lipid nanoparticles (SLNs) administering the neurotransmitter dopamine (DA) and the antioxidant grape-seed-derived proanthocyanidins (grape seed extract, GSE) have been prepared by us in view of a possible application for Parkinson’s disease (PD) treatment. To develop powders constituted by such SLNs for nasal administration, herein, two different agents, namely sucrose and methyl-β-cyclodextrin (Me-β-CD), were evaluated as cryoprotectants. (2) Methods: SLNs were prepared following the melt homogenization method, and their physicochemical features were investigated by Raman spectroscopy, Scanning Electron Microscopy (SEM), atomic force microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). (3) Results: SLN size and zeta potential values changed according to the type of cryoprotectant and the morphological features investigated by SEM showed that the SLN samples after lyophilization appear as folded sheets with rough surfaces. On the other hand, the AFM visualization of the SLNs showed that their morphology consists of round-shaped particles before and after freeze-drying. XPS showed that when sucrose or Me-β-CD were not detected on the surface (because they were not allocated on the surface or completely absent in the formulation), then a DA surfacing was observed. In vitro release studies in Simulated Nasal Fluid evidenced that DA release, but not the GSE one, occurred from all the cryoprotected formulations. Finally, sucrose increased the physical stability of SLNs better than Me-β-CD, whereas RPMI 2650 cell viability was unaffected by SLN-sucrose and slightly reduced by SLN-Me-β-CD. (4) Conclusions: Sucrose can be considered a promising excipient, eliciting cryoprotection of the investigated SLNs, leading to a powder nasal pharmaceutical dosage form suitable to be handled by PD patients.

Fully coupled numerical analysis for induction skull melting technology applied for metallic glass component alloy

High-purity melting is critical for casting metallic glass components, which would be achieved by developing the induction skull melting (ISM) technology used in casting process. The melting process of metallic glass components during ISM is urgently desired to be understood, which is rare so far. Based on this, a full-scale coupling simulation model for ISM technology with finite element method (FEM) was proposed, which contains all physical fields engaged in the melting processes. Furthermore, the metallic glass melting process was experimentally and numerically investigated based on the full-scale coupling model. The distribution of the multi-physics field within the charge was elaborated based on the numerical simulation results, especially electromagnetic field contribution, heat transfer, meniscus shape and melt reflux zone. Furthermore, due to its high viscosity, a long holding time to improve melt homogeneity is necessary for metallic glass melt. The chief aim of this work is to understand of induction melting process for melting amorphous master alloys using induction skull melting technology and to provide a foundation for the casting method to form bulk metallic glasses.

Microstructure and mechanical properties of Al0.4Co0.5V0.6FeNi high-entropy alloys processed by homogenization treatment

Al0.4Co0.5V0.6FeNi high-entropy alloys (HEAs) are fabricated by the vacuum arc melting method and homogenization treatment (HT) at 1000, 1100 and 1200 °C for 5 h (samples denoted as HT-1000, HT-1100 and HT-1200, respectively), followed by water quenching. The microstructural characteristics and mechanical properties of the HEAs are investigated by a combination of optical, scanning and transmission electron microscopy, X-ray diffraction and tension tests. The solidification of the Al0.4Co0.5V0.6FeNi HEAs is calculated using Pandat software to show that the FCC phase forms in the liquid phase, which then undergoes a eutectic reaction to form the FCC and BCC/B2 phases. The Al0.4Co0.5V0.6FeNi HEAs exhibit a typical eutectic microstructure with an alternating lamellar structure. Compared with that in the as-cast state, the volume fraction of the FCC phase in the HT state increases from 53.16% to 60.75% and the yield strength of the HT-1200 alloy increases by ∼27.5% with increasing homogenization temperature. Fine small spherical and ellipsoidal nanoprecipitates are uniformly distributed within the FCC matrix. These FCC phase nanoprecipitates become the most important factor contributing to the yield strength.

Additive manufacturing of titanium alloys with enhanced strength and uniform ductility via multi-element alloying

The application of commercially pure titanium (CP–Ti) has long been limited by its insufficient strength and plastic instability. However, strength enhancement typically comes at the expense of ductility since the two important mechanical properties are often mutually exclusive. In the present work, multi-element Fe–Cr–Ni–Mo in the form of 316L steel was added into CP-Ti by additive manufacturing (AM), so as to realize the simultaneous enhancement of strength and uniform ductility. The localized homogenization of CP-Ti and 316L alloy melts during laser melting deposition produced the microstructure comprised of basket-weave ɑ laths, discontinuous ɑGB, and retained β phases, which endowed Ti-1.35Fe-0.36Cr-0.24Ni-0.05Mo alloy with related higher ultimate tensile strength (635 MPa) and larger uniform ductility (12%). This approach could provide guidance for designing high-performance metal materials starting with elements powder through additive manufacturing.

Effect of rare earth element Er on the microstructure and properties of highly alloyed Al-Zn-Mg-Cu-Zr-Ti alloy

By using standard melting casting, homogenization, extrusion, solid solution, and T6 aging, an Al-11Zn-3.1Mg-1.2Cu-0.2Zr-0.16Ti alloy was created, and the microstructure and mechanical properties of the alloy with various Er contents were investigated. The inclusion of Er promoted the increase in the number density and volume fraction of L12-Al3(Er, Zr) in the alloy, which greatly reduced the alloy's tendency to recrystallize, raised the internal dislocation density, and helped the alloy achieve grain refinement. To a certain extent, a moderate amount of Er added to the alloy may have helped the precipitation and phase transformation of precipitates. When the Er concentration rose from 0.15 to 0.45 wt.%, the refining effect and the density of L12-Al3(Er, Zr) were less influenced, but excessive Er interacted with other elements to form coarse intermetallic compounds, leading to the deterioration of mechanical properties. The yield strength (YS) and ultimate tensile strength (UTS) of the alloy grew first and then declined and flattened as the Er content increased from 0 to 0.45 wt.%, according to the mechanical properties test. All alloys with Er microalloying had superior elongation due to the decrease of number of high-angle grain boundary (HAGB). The optimal mechanical properties were shown in the 0.15 wt.% Er alloy, with a YS of 771.7 MPa, a UTS of 785.9 MPa, and an elongation of 9.5%.

Effect of Molecular Weight on the Dissolution Profiles of PEG Solid Dispersions Containing Ketoprofen

Solid dispersions are typically binary systems with a hydrophilic matrix polymer and a lipophilic active substance. During formulation, the drug undergoes a crystalline to amorphous phase transition, which leads to a supersaturated solution providing enhanced bioavailability. The interaction of the active substance and the polymer is unique and influences the level of supersaturation. We aimed to investigate the relationship between low molecular weight polyethylene glycol derivates PEG 1000, 1500, and 2000 and ketoprofen regarding the effect of molecular weight. The physicochemical properties of solid dispersions prepared with hot melt homogenization and their respective physical mixtures were investigated with Fourier transform infrared spectroscopy, powder X-ray diffraction and scanning electron microscopy techniques. A phase solubility study was carried out in hydrochloric acid media which showed no difference between the three polymers, but the dissolution curves differed considerably. PEG 1000 had higher percentage of released drug than PEG 1500 and 2000, which had similar results. These results indicate that when multiple low molecular weight PEGs are suitable as matrix polymers of solid dispersions, the molecular weight has only limited impact on physicochemical characteristics and interactions and further investigation is needed to select the most applicable candidate.

Mechanism and Kinetics of Interaction of FLiNaK–CeF3 Melt with Water Vapors and Oxygen in the Air Atmosphere

The mechanism and kinetic parameters of the interaction of the FLiNaK–CeF3 melt with water vapors and oxygen in the air atmosphere were determined using Raman and IR spectroscopy, XRD analysis, and thermodynamic modeling of processes. The presence of the 4CeF3(solution) + 6H2O (gas) + O2(gas) = 4CeO2(solid) + 12HF(gas) reaction, which disturbs the fluoride melt homogeneity, was verified in situ by Raman spectroscopy adopted for high-temperature, chemically aggressive fluoride systems. Based on the obtained spectral data, the type of the kinetic equation, order, and rate constant of the chemical reaction were determined. The concentration of cerium dioxide was found to increase linearly in time and a zero reaction order with respect to CeO2 was detected. The change in the concentration of CeO2 over time at T = 510 °C is described by the equation C = 0.085t; the reaction rate constant is 0.085 mol. %∙min−1. The obtained kinetic parameters may be used to model emergencies related with the depressurization of the coolant circuit or the working area of the molten salt reactor.

Early Palaeozoic intracontinental orogeny in South China Block: Insights from migmatites and potassic mafic rocks in southern Guangdong

ABSTRACT The early Palaeozoic orogen in South China is considered as one of the typical examples of intraplate orogens in the world. However, the nature of the orogen, for example, the onset time and the timing of tectonic transition from syn-orogenic compression to post-orogenic extension, are still controversial. Here, we present new zircon U–Pb age and Hf isotope data, and whole-rock geochemical and Sr–Nd isotopic data for migmatites and potassic mafic rocks in southern Guangdong, from the Cathaysia Block, South China. Migmatites consist of metatexite and diatexite, including various amounts of palaeosome, melanosome, and leucosome. Leucosomes from metatexite and diatexite/migmatite granite samples yield consistent U–Pb ages of 451.5 ± 2.0 Ma to 458 ± 16 Ma, respectively. Zircon U–Pb dating from two potassic plutons yield consistent crystallization ages of 451–446 Ma. Our new results of field investigation, mineralogy and microstructures, geochronology, and geochemical compositions demonstrate that the protoliths of migmatites are metasedimentary rocks, while metatexites and diatexites are the products of variable degrees of partial melting of the protolith. The potassic rocks have SiO2 contents ranging from 52.5 to 60.2 wt.%, high K2O/Na2O ratios (0.7–1.3), with MgO contents of 3.0–6.2 wt.% and Mg number of 42–57. They have enriched Sr–Nd–Hf isotopic compositions with (87Sr/86Sr)i ratios of 0.7085–0.7151, ɛNd(t) values of −9.9 to −6.2, and εHf (t) values of −10.5 to −5.3, indicating that they were generated from an enriched mantle source modified by ancient oceanic subducted sediments. Regional crustal anatexis occurred at about 451 Ma, and the timescale from crustal anatexis to melt homogenization and accumulation spans over an interval of ~15 Myr. The association of migmatites and the potassic rocks may form in post-orogenic extension setting. Thus, we suggest that the tectonic transition from syn-orogenic compression to post-orogenic extension occurred by the Late Ordovician (ca. 451–446 Ma) for the early Palaeozoic orogen in South China.

Comparative study on the performance of monoolein cubic nanoparticles and trimyristin solid lipid nanoparticles as carriers for docetaxel

Nowadays the application of lipid nanoparticles as carriers for the delivery of anticancer drugs gained great attention in cancer therapy. Solid lipid nanoparticles (SLNs) and cubic nanoparticles (cubosomes) are considered as promising carriers in cancer therapy. The comparison of these two lipid nanoparticles as efficient carriers for the anticancer drug docetaxel was our main goal in this study. Both nanoparticles were prepared by the hot melt homogenization technique followed by measurement of particle size, zeta potential, entrapment efficiency and in vitro release of docetaxel. An advanced technique has been applied to measure the release of docetaxel from these nanoparticles using small unilamellar vesicles (SUVs) as acceptor particles which resemble many compartments in our body. All prepared nanoparticles revealed a neutral zeta potential with particle sizes of about 200 nm. While SUVs showed a negative surface charge with a zeta potential of −55 mV, cubosomes showed higher entrapment efficiency and a slower docetaxel release compared to SLNs. Additionally, cubosomes improved in vitro cytotoxicity as well as the in vivo antitumor inhibition of docetaxel compared to SLNs and docetaxel solution. Overall, our results showed that incorporation of docetaxel into cubosomes could enhance its in vitro and in vivo performance compared to docetaxel incorporated into SLNs.

Effect of pre-existing crystals and melt homogeneity on the decompression-induced crystallization of hydrous rhyodacite magma

Abstract Decompression-induced crystallization is an important process that controls the behavior of volcanic eruptions because it strongly affects magma rheology and degassing behavior in the shallow parts of volcanic conduits. Several decompression experiments have been performed to understand and model the crystallization processes; however, the effect of superheating (i.e., heating above the liquidus temperature for a definite period of time) before decompression has not been elucidated, despite the proposal of its importance in previous cooling experiments. As the superheating influences the number of pre-existing crystals and melt homogeneity, it is expected to control decompression-induced crystallization. In this study, we investigated the effects of pre-existing crystals and melt homogeneity on crystallization during the decompression of rhyodacitic magma at a temperature of 900 °C. The magma studied herein has a liquidus temperature of ~920 °C. Five starting materials were prepared via heating at different super-liquidus temperatures (940, 970, 1050, and 1300 °C) and a sub-liquidus temperature (900 °C) using an internally heated pressure vessel and a cold-seal pressure vessel, respectively. Decompression experiments using these starting materials were conducted from 130 to 30 MPa at decompression rates of 5, 20, and 100 MPa h–1. When the melt was completely homogenized (at 1050 and 1300 °C), no crystals were formed at 100 MPa h–1 and the small amounts of crystals heterogeneously formed along the capsule wall were found at 5 and 20 MPa h–1. At the same decompression rate, the number density of plagioclase formed during decompression increased as the superheating temperature decreased from 970 to 900 °C, despite the higher number densities of pre-existing crystals before decompression in the samples with lower superheating. Such finding indicates that nucleation occurs easily when the number density is initially high. This result is inconsistent with the idea that nucleation occurs when supersaturation is sufficient to overcome the energy barrier for nucleation, and the growth of pre-existing crystals decreases supersaturation. In contrast, the results of our experiments can be explained by considering that higher superheating results in a more homogeneous melt structure with few pre-crystal clusters, which are growth sites, and ultimately the suppression of nucleation. Based on these results, we conclude that pre-existing crystals and melt homogeneity strongly affect the crystal texture formed by decompression. For application to natural systems, the high number density of microlites found in natural samples may be due to heterogeneous nucleation caused by the presence of pre-crystal clusters and other mechanisms. Furthermore, the superheating of magma in a reservoir caused by the injection of high-temperature mafic magma may influence the crystal texture during magma ascent and, hence, control the explosivity of the eruption.

Electrovortex flow and melt homogenization in the industrial direct current electrical arc furnace

Electrovortex flow and melt homogenization in the industrial direct current electrical arc furnace

The Process of Melt Homogenization in a Metered-Discharge Disk Extruder

Purpose. This paper aims to develop a physical model of the homogenization process in a metered-discharge disk extruder, as well as to select and justify the variable parameters that can be used to evaluate the efficiency of mixing and process control. Methodology. With the advent of a large number of alloying additives, filled and composite materials, there is a need for continuous monitoring and control of the melt homogenization process. In classical worm extruders, the processes of feeding, melting, homogenization, and pressure generation are interconnected and are triggered simultaneously by a single working body, the worm, which makes it impossible to control each process separately to optimize them. In such cases, cascade extrusion schemes are used, where the process is divided into separate subprocesses or groups of them with the ability to control them independently. Findings. The scheme of a cascade disk-gear extruder is described, where a metered-powered disk extruder is used as a melt-homogenizer, and a gear pump is used to create pressure and dosing. The variable parameters of the disk extruder for adjusting the mixing efficiency are selected and substantiated. The speed components and their ratios for different parts of the homogenization zone are analyzed. The expediency of using a disk extruder as a melt-homogenizer in cascade extrusion schemes is substantiated. The adequacy of using the mixing index in the form of temperature inhomogeneity is emphasized. The homogenization zone in the form of four separate subzones and changes in the accumulated shear strain along each subzone, as well as the possibility of their regulation, are described. Originality. For the first time, a hydrodynamic model of processes in the homogenization zone of a metered-discharge disk extruder was developed and described. Practical value. The possibility of adjusting the velocity field in the homogenization zone of a disk extruder has been substantiated, which allows controlling the mixing effect directly during the extrusion process. The possibility of selecting the optimal mode of operation of the homogenization zone makes it possible to obtain a melt of a given quality with minimal energy consumption.

Development and Optimization of Solid Lipid Nanoparticle Based Gel of Desoximetasone

Background: The present study enlightens to enhance the residence time and prolonged release of the desoximetasone by incorporating it into solid lipid nanoparticles (SLN), prepared by hot melt homogenization process. The desoximetasone loaded SLN were incorporated into gel for topical application. Materials and Methods: The preliminary trial batches were carried out by varying the concentration of Poloxamer 188 and lipid concentration. The prepared solid lipid nanoparticles were evaluated for particle size and % entrapment efficiency. From preliminary batches, the levels of Poloxamer 188, Glyceryl Monostearate and Homogenization speed were selected. Desoximetasone loaded SLN were optimized by box-behnken design by Design Expert 10.0.1.0 software. Results: Optimization was done to study influence of X1-amount of lipid, X2-surfactant concentration and X3-speed of homogenization on particle size(Y1), polydispersity index(Y2) and % entrapment efficiency(Y3). From overlay plot, 3.330 g (X1), 0.542 g (X2) and 20930 rpm (X3) were selected. It was observed that there was influence of independent variables over dependent variables. Transmission Electron Microscopy was performed to physically check prepared SLNs. It was observed that majority of SLNs were in the range of 150-200nm. Various parameters like pH, Spreadability, Viscosity, % drug release in 24 hrs of optimized batch was found to be 7.1 ±0.04, 40.99 ± 0. 32g.cm/sec, 10255 ± 18.78 cps, 90.89 ± 0.52% respectively. Accelerated Stability study revealed that there were no significant changes observed upon accelerated stability conditions. Conclusion: Prolonged release of desoximetasone was achieved by preparing desoximetasone loaded SLN based gel for topical application.

Effect of Recycling on the Mechanical, Thermal and Rheological Properties of Polypropylene/Carbon Nanotube Composites

In this research the effect of physical recycling on the mechanical, thermal, and rheological properties of polypropylene (PP)/multiwalled carbon nanotube (MWCNT) was investigated. After melt homogenization by extrusion, specimens were injection moulded with 0.1 and 0.5 wt% MWCNT content. The recycling process was simulated by multiple grinding and re-moulding, then we compared the behavior of original and recycled PP/MWCNT composites. Differential scanning calorimetry (DSC) measurements proved that MWCNT had double the effect on the morphology of the PP matrix: on the one hand nucleating effect can be detected because 0.5 wt% MWCNT increased the onset temperature of crystallization by 10 °C, compared to the basic PP material; on the other hand, the crystalline fraction of the recycled composite materials decreased compared to the original PP material with the same MWCNT content. This resulted in a slight decrease in strength and stiffness but an increase in elongation at break. However, compared to the original unreinforced PP reference, even the recycled materials have better properties. The mechanical test results showed that recycled PP/MWCNT 0.5 wt% increased the elastic modulus (~15%) and decreased the tensile strain at yield (~10%). However, in the values of tensile stress at yield, relevant difference was not found. It was also shown by oscillatory rheometry that MWCNT had a significant effect on the rheological properties (storage and loss modulus, complex viscosity) of PP compounds in a wide temperature range (190-230 °C).