Narrow Size Distribution Range Research Articles

Cannabidiol-loaded microparticles embedded in a porous hydrogel matrix for biomedical applications

In this study, poly (lactic-co-glycolic acid) (PLGA) microparticles loaded with cannabidiol (CBD) were synthesized (PLGA@CBD microparticles) and embedded up to 10 wt% in a chondroitin sulfate/polyvinyl alcohol hydrogel matrix. In vitro chemical, physical, and biological assays were carried out to validate the potential use of the modified hydrogels as biomaterials. The microparticles had spherical morphology and a narrow range of size distribution. CBD encapsulation efficiency was around 52%, loading was approximately 50%. Microparticle addition to the hydrogels caused minor changes in their morphology, FTIR and thermal analyses confirmed these changes. Swelling degree and total porosity were reduced in the presence of microparticles, but similar hydrophilic and degradation in phosphate buffer solution behaviors were observed by all hydrogels. Rupture force and maximum strain at rupture were higher in the modified hydrogels, whereas modulus of elasticity was similar across all materials. Viability of primary human dental pulp cells up to 21 days was generally not influenced by the addition of PLGA@CBD microparticles. The control hydrogel showed no antimicrobial activity against Staphylococcus aureus, whereas hydrogels with 5% and 10% PLGA@CBD microparticles showed inhibition zones. In conclusion, the PLGA@CBD microparticles were fabricated and successfully embedded in a hydrogel matrix. Despite the hydrophobic nature of CBD, the physicochemical and morphological properties were generally similar for the hydrogels with and without the CBD-loaded microparticles. The data reported in this study suggested that this original biomaterial loaded with CBD oil has characteristics that could enable it to be used as a scaffold for tissue/cellular regeneration.Graphical

Uniformly Dispersed Nano Pd-Ni Oxide Supported on Polyporous CeO2 and Its Application in Methane Conversion of Tail Gas from Dual-Fuel Engine

The development of catalysts for low-temperature methane combustion is crucial in addressing the greenhouse effect. An effective industrial catalyst strategy involves optimizing noble metal utilization and boosting metal–metal interaction. Here, the PdNi-H catalyst was synthesized using the self-assembly method, achieving the high dispersion and close proximity of Pd and Ni atoms compared to the counterparts prepared by the impregnation method, as confirmed by EDS mapping. The XRD and TEM results revealed Pd2+ and Ni2+ doping within the CeO2 lattice, causing distortions and forming Pd-O-Ce or Ni-O-Ce structures. These structures promoted oxygen vacancy formation in CeO2, and this was further confirmed by the Raman and XPS results. Consequently, the PdNi-H catalyst demonstrated an excellent redox ability and catalytic activity, achieving lower ignition and complete methane burning temperatures at 282 and 387 °C, respectively. The highly dispersed PdNi species played a pivotal role in activating methane for enhanced redox ability. Additionally, the narrow size distribution range contributed to more vacancies on the surface of CeO2, as confirmed by the XPS results, thereby facilitating the activation of gas phase oxygen to form oxygen species (O2−). This collaborative catalytic approach presents a promising strategy for developing efficient and stable methane combustion catalysts at low temperatures.

Effect of Heat Treatment on Yellow Field Pea (Pisum sativum) Protein Concentrate Coupled with Membrane Ultrafiltration on Emulsification Properties of the Isolated >50 kDa Proteins.

The aim of this paper was to determine the emulsification properties of protein aggregates obtained from heat pretreated yellow field pea protein concentrate (PPC). PPC dispersions were prepared in distilled water (adjusted to pH 3.0, 5.0, 7.0, or 9.0), heated in a water bath (100 °C) for 30 min, centrifuged and the supernatant passed first through a 30 kDa membrane and, then, the first retentate (>30 kDa) through a 50 kDa membrane. The 50 kDa membrane separation yielded a second retentate (>50 kDa proteins), which was isolated for emulsification studies. The near UV circular dichroic spectra of the protein samples showed more unfolded structures at pH 3.0 and 5.0 than at pH 7.0 and 9.0. The presence of small and spherical oil droplets of emulsions stabilized by the >50 kDa proteins at pH 3.0, 7.0, and 9.0 was confirmed by confocal laser scanning microscopy images. Emulsions stabilized at pH 7.0 and 9.0 had a narrower size distribution range than at pH 3.0 and 5.0. A narrow oil droplet size distribution range and lower interfacial protein concentrations of the emulsions stabilized by the >50 kDa proteins were observed at the corresponding pH of the heat treatment when compared to other pH values. Emulsions stabilized by the >50 kDa proteins exhibited a relatively low flocculation and coalescence index, which infers relative stability. The results from this work suggest that heat pretreatment of the PPC led to the formation of new protein aggregates, especially FT9 with enhanced emulsification properties, at some of the test conditions when compared to the unheated PPC.

Sulfated Well-Defined Mesoporous Nanostructured Zirconia for Levulinic Acid Esterification.

Well-organized zirconia (ZrO2) nanoparticles forming mesoporous materials have been successfully synthesized via a facile micelle-templating method using cetyltrimethylammonium bromide as a structure-directing template to control the nucleation/growth process and porosity. The systematic use of such a surfactant in combination with a microwave-assisted solvothermal (cyclohexane/water) reaction enabled the control of pore size in a narrow-size distribution range (3–17 nm). The effect of solvent mixture ratio on the porosity of the synthesized oxide was determined, and the controlled growth of zirconia nanoparticles was confirmed by means of powder X-ray diffraction, small-angle X-ray scattering, transmission electron microscopy, selected area electron diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and Fourier transform infrared spectroscopy as well as N2 physisorption isotherm analysis. Then, the as-prepared nanostructured zirconia oxides were treated with sulfuric acid to have sulfated samples. The catalytic performances of these mesoporous zirconia nanoparticles and their sulfated samples were tested for levulinic acid (LA) esterification by ethanol, with quantitative conversions of LA to ethyl levulinate after 8 h of reaction.

Amphipathic anionic surfactant modified hydrophilic polyethylene glycol-nanosilica composite as effective viscosifier and filtration control agent for water-based drilling muds

Highly stabilized and dispersible composites of polyethylene glycol and silica nanoparticle in aqueous drilling mud can provide desirable rheological and filtration properties for drilling jobs. Therefore, high-quality hydrophilic polyethylene glycol-nanosilica composite modified by amphipathic anionic sodium dodecyl sulfate (PEG-SiO2 NC-SDS) to improve the rheological and filtration properties of water-based muds (WBMs) was submitted. Test of zeta potential, functional groups, morphology, elemental composition, and temperature stability together with rheology and filtration tests were undertaken to assess the wide-ranging mud properties of the SDS modified PEG-SiO2 NC drilling muds. Zeta potential, FTIR, FESEM, EDX, and TGA results indicate that the SDS modified PEG-SiO2 NC was effectively formed and modified; it embodies exceptional thermal stability and is efficiently dispersed. The SDS modified PEG-SiO2 NC has a narrow size distribution range between 82 nm and 410 nm, and a specific surface area of 41.4 m2/g that is sufficiently high for particle-molecule interactions. Its rheological variables are notably shear-thinning and did not undergo notable fluctuation. The filtrate loss of 1.5 g SDS bearing PEG-SiO2 NC at 78 °F and 250 °F was only 5.4 ml and 9.6 ml, against 10.2 ml and 20.5 ml of the WBMs, respectively. High dispersion stability and high thermal stability aided its excellent viscosity and filtration control performance. Moreover, optimum rheological properties for the SDS modified PEG-SiO2 NC drilling muds with Bingham plastic and Ostwald-de-Waele models occurred with mud composition CD3 (CD3 = 1.5 g SDS modified PEG-SiO2 NC + WBM). Thus, this study can help to understand the applications of this nanocomposite as a potential viscosifier and filtrate loss control material for WBMs.

Preparation of L-cysteine modified MnFe2O4 nanoparticles based on high-gravity technology and application for the removal of lead

MnFe2O4 nanoparticles, usually applied as a magnetic adsorbent for removing heavy metals in wastewater, have attracted widespread attention for the characteristics of excellent magnetic properties and chemical stability. This study firstly used high-gravity technology coupled with surface modification by L-cysteine to prepare novel L-cysteine modified MnFe2O4 nanocomposite (MnFe2O4-Cys) with small size (< 10 nm), narrow size distribution range and good dispersion in water, and serves as the efficient adsorbent for Pb(II) removal from water. The different preparation conditions were optimized and the obtained products were charactered through a series of characterization methods. As compared to a traditional stirred reactor, the MnFe2O4-Cys prepared via high-gravity technology using impinging stream-rotating packed bed (IS-RPB) reactor (MnFe2O4-Cys-R) has higher crystallinity and saturation magnetization (57.16 emu·g-1). As seen from TEM images and DLS results, the MnFe2O4-Cys-R exhibits a small average size of 7.25 nm and good dispersion in water. Besides, the BET specific surface area of MnFe2O4-Cys-R (169.63 m2·g-1) is 31.2% higher than that of unmodified MnFe2O4 (129.26 m2·g-1) prepared by IS-RPB reactor (MnFe2O4-R). The adsorption behavior of Pb(II) on MnFe2O4-Cys-R is best described by pseudo-second-order kinetic and Temkin isotherm models, respectively, whereas Elovich kinetic and Freundlich isotherm models are best for describing the adsorption of Pb(II) on MnFe2O4-R. The realized experimental maximum adsorption capacity of MnFe2O4-Cys-R is 137.45 mg·g-1, which is 1.98 times that of MnFe2O4-R (69.50 mg·g-1). This study provides a new route for production of small uniform MnFe2O4 nanoparticles with excellent magnetic and adsorption performance for wastewater treatment.

Preparation of β-FeOOH by ultrasound assisted precipitation route for aqueous supercapacitor applications

Iron oxide (β-FeOOH) nanoparticles were prepared by a simple precipitation method assisted by ultrasound at room temperature. Formation of phase pure β-FeOOH material was confirmed through the Reitveld refined XRD and FTIR analysis. The β-FeOOH nanoparticles prepared was found to have a narrow size distribution range with an average particle size of 138 nm. The optical band gap of the material was found to be 2.6 eV. The electrochemical performance of β-FeOOH was studied in a three electrode system using β-FeOOH coated on graphite sheet as the working electrode. The Ag/AgCl and platinum was used as the reference and counter electrodes, respectively. The KOH in distilled water was used as the aqueous electrolyte. The specific capacitance of the above material at a high current density of 1 A/g for 1 M, 3 M and 5 M aqueous KOH electrolyte was found to be 68.66, 138.67 and 88.17 F/g, respectively.

Performance of simvastatin microsponges as a local treatment for chronic periodontitis – Randomized clinical trial

Simvastatin (SV) is a lipid lowering drug exhibits anti-inflammatory and anabolic effects on the bone, so it could be utilized for the local treatment of periodontitis. However, the poor solubility of SV limits its penetration through the gingival sulcus. Encapsulating SV into microsponges may have the potential to enhance the dissolution and subsequently its local penetration. In this study, SV microsponges had been prepared using the emulsion-solvent evaporation technique where, Eudragit RS-100 was employed as the polymer. The % encapsulation efficiency(%EE) of drug approached 77.32 ± 2.03. The prepared microsponges were free flowing, spherical in shape having narrow size distribution range. The particle size of the prepared microsponges was 93.79 ± 7.21 μm in diameter with a small polydispersity index (PDI) of 0.0059 ± 0.0008. In-vitro dissolution studies of SV microsponges showed that the solubility of SV had significantly enhanced upon inclusion inside the microsponges. Fourier transform infrared (FT-IR) spectroscopy indicated hydrogen bond formation between SV and Eudragit RS-100. The prepared microsponges were incorporated in chitosan 2% gels. A clinical study was conducted on 24 selected patients having bony periodontal defects to compare the efficacy of chitosan 2% gel containing free (SV) with that containing SV microsponge in treatment of chronic periodontitis. Results showed that the chitosan gels containing SV microsponges exhibited significant reduction in both pocket depth and clinical attachment loss compared to those prepared with free SV. This might be attributed to hydrogen bond formation between microsponges entrapped SV and chitosan, thus microsponges are auspicious as a carrier for SV for local treatment of periodontitis.

Rambutan (Nephelium lappaceum) kernel olein as a non-hydrogenated fat component for developing model non-dairy liquid creamer: effect of emulsifier concentration, sterilization, and pH.

In this work, the effects of the emulsifier concentration, sterilization process, and pH on the properties and stability of the model liquid creamer were evaluated. Applying diacetyl tartaric acid ester of mono- and diglycerides or DATEM at a concentration of 0.3% (w/w) in the presence of 2% (w/w) sodium caseinate produced stable model liquid creamers (10% (w/w) rambutan kernel olein) with a small particle size (Z-average ≈ 200nm) and a narrow size distribution range (PDI < 0.24). These creamers were stable regarding creaming and coalescence, having non-flocculated particles and a constant flow behavior index (n) after sterilization using autoclaving (121°C, 1.1bar for 15min) and during storage for 150days at 25°C. The model liquid creamers were unstable at pH values near the isoelectric point of caseinate (pH 4-5). However, these were stable after mixing with hot coffee solutions based on no observed feathering or sedimentation. The whitening performance of the model liquid creamers compared well with commercial ones. Non-hydrogenated fat-based model non-dairy liquid creamer was successfully formulated using rambutan kernel olein as a fat component. The results obtained in this study are useful for the possible application of fractionated rambutan kernel fat in food products.

Morphologically controlled synthesis of ferric oxide nano/micro particles and their catalytic application in dry and wet media: a new approach

Morphologically controlled synthesis of ferric oxide nano/micro particles has been carried out by using solvothermal route. Structural characterization displays that the predominant morphologies are porous hollow spheres, microspheres, micro rectangular platelets, octahedral and irregular shaped particles. It is also observed that solvent has significant effect on morphology such as shape and size of the particles. All the morphologies obtained by using different solvents are nearly uniform with narrow size distribution range. The values of full width at half maxima (FWHM) of all the products were calculated to compare their size distribution. The FWHM value varies with size of the particles for example small size particles show polydispersity whereas large size particles have shown monodispersity. The size of particles increases with decrease in polarity of the solvent whereas their shape changes from spherical to rectangular/irregular with decrease in polarity of the solvent. The catalytic activities of all the products were investigated for both dry and wet processes such as thermal decomposition of ammonium per chlorate (AP) and reduction of 4-nitrophenol in aqueous media. The results indicate that each product has a tendency to act as a catalyst. The porous hollow spheres decrease the thermal decomposition temperature of AP by 140 °C and octahedral Fe3O4 particles decrease the decomposition temperature by 30 °C. The value of apparent rate constant (kapp) of reduction of 4-NP has also been calculated.

Influence of temperature and synthesis time on shape and size distribution of Fe3O4 nanoparticles obtained by ageing method

Fe3O4 nanoparticles have been obtained by ageing method under controlling such conditions as follows: temperature, oxidation time, ageing time. Fe3O4 nanopowders have been examined by a transmission electron microscopy (TEM) and by X-ray diffractometry (XRD). XRD results showed that under time of the oxidant addition up to 30min only a crystalline phase of magnetite had been formed and also under such condition but time of the oxidant addition more then 30min an γ-FeOOH phase had been revealed. It has been established that size of Fe3O4 nanoparticles increased in the range of 42nm to 81nm with the increasing time of the ageing process. In order to obtain Fe3O4 nanoparticles with a narrow range of size distribution, optimal parameters have been determined. Nanoparticles with the standard deviation equal to 10nm have been obtained with an ambient temperature during the deposition process (deposition temperature) of 10°С and with an ambient temperature during the ageing process (ageing temperature) of 40°С.

Preparation and Characterisation of Sr2CeO4:Eu3+ Rare Earth Luminescent Material by High Temperature Mechano-Chemical Method

A novel, high-temperature, mechano-chemical (HTMC) method was developed to synthesise single-phase Sr2CeO4:Eu3+ phosphor. Phosphors were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and luminescence spectra. Compared with phosphors prepared by the traditional high-temperature solid state method and citric acid gel method, single-phase Sr2CeO4:Eu3+ powders by using the HTMC method, with small average particle sizes of about 5 µm, a narrow size distribution range and uniform dispersion, were prepared at 800 °C, and reached their maximum luminescent intensity at 900 °C. Under ultraviolet excitation at 298 nm, the sample showed good luminescence with the strongest red light of 616 nm. However, Sr2CeO4:Eu3+ was prepared at the higher temperature of 1100 °C by solid state method and citric acid gel method. The particle size was too large and uneven with phosphor agglomeration by high-temperature solid state method. The luminescent intensity reached a maximum for Sr2CeO4:Eu3+ phosphor at a synthesis temperature of 1100 °C by using the high-temperature solid state method, and at 1200 °C by both citric acid gel and chemical precipitation methods. Furthermore, the advantages of the Sr2CeO4:Eu3+ powder prepared by HTMC method were discussed compared with that prepared using traditional high-temperature solid state and citric acid gel methods.

Enhanced Heat Resistance of Al-Cu-Mg Alloy by a Combination of Pre-stretching and Underaging

Enhanced heat resistance of Al-Cu-Mg alloy by employing a combined effect of pre-stretching and underaging has been characterized by thermal exposure, tensile testing, transmission electron microscopy (TEM) examination, and quantitative analysis. Tensile testing results showed that the samples subjected to both pre-stretching and underaging processing, presented a high tensile strength up to 440 MPa after thermal exposure at 200 °C for 500 h. This suggests that the long-time application temperature of Al-Cu-Mg alloys, which were normally applied at elevated temperature below 150 °C or even below 100 °C, can be raised to 200 °C by employing a combined effect of pre-stretching and underaging. TEM results showed that a fine and a narrow size distribution range of S′ phase was formed by the combined processing of pre-stretching and underaging, as compared to that without pre-stretching. Quantitative analysis results indicated that this narrow range of size distribution greatly reduced the growth rate of S′ phase during thermal exposure. It is suggested that this effect was ascribed to the Ostwald ripening mechanism.

Microwave-assisted synthesis of mesoporous nano-hydroxyapatite using surfactant templates

Mesoporous nano-hydroxyapatite (mn-HAP) was expeditiously synthesized using a pseudo sol–gel microwave-assisted protocol in the presence of two novel templates, namely sodium lauryl ether sulfate (SLES) and linear alkylbenzenesulfonate (LABS). The cooperative self-assembly of the calcium precursor with the surfactant molecules, followed by the interaction with the PO43− ligand, led to the formation of mesoporous nano-hydroxyapatite with controlled pore sizes. The systematic use of these surfactants in combination with microwave energy input enables the precise control of pore size within a narrow-size distribution range (35 nm). The controlled growth of hydroxyapatite is confirmed using several techniques such as thermogravimetric analysis (TGA), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), low-angle X-ray diffraction, transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM) and N2 physisorption isotherm analysis.

Synthesis of mesoporous nano-hydroxyapatite by using zwitterions surfactant

Mesoporous nano-hydroxyapatite (mn-HAP) was successfully synthesized via a novel micelle-templating method using lauryl dimethylaminoacetic acid as zwitterionic surfactant. The systematic use of such a surfactant in combination with microwave energy input enables the precise control of pore size in a narrow-size distribution range (36nm). The comparison of the specific surfaces area of dried and calcined mn-HAP (87m2g−1 and 55m2g−1, respectively) illustrates the fundamental role of zwitterionic surfactant in the synthesis of mn-HAP. The controlled growth of hydroxyapatite is confirmed by means of thermogravimetric analyses (TGA), Fourier transform infrared (FT-IR) and Raman spectroscopy, powder X-ray diffraction (XRD), solid-state NMR, N2 adsorption–desorption measurements (BET), and transmission electron microscopy (TEM) techniques.

Experimental Investigation of the VAPEX Process in Vuggy Porous Media

Summary In this paper, the application of the vapor extraction (VAPEX) process was investigated to recover Cold Lake bitumen from vuggy porous media with n-pentane as the hydrocarbon solvent. Seven different sintered glass-bead models were designed and fabricated—four of which were vugular media with different vuggy- to total-pore-volume (PV) ratios. The vugs were arranged in aligned and staggered configurations. Three homogeneous sintered glass-bead models of different permeability and porosity were also fabricated to serve as baselines. The vug sizes were controlled in a narrow size-distribution range by embedding wood particles of uniform volumes (20 mm3 each) in the packing of the glass-bead continuum, sandwiched between two parallel glass plates. The packing assembly was then sintered in the muffle furnace. For each particular VAPEX experiment, the oil-recovery performance was characterized by measurements [e.g., live-oil and dead-oil production rates, live-oil solvent content, and Residual Oil Saturation (ROS) (in the invaded area of the models)]. It was observed that the vugs significantly facilitated the live-oil production from the vuggy models compared with the corresponding homogeneous baseline model with the same matrix permeability. The increase in the vug porosity of the porous space significantly increased the live- and dead-oil production rates, and it slightly decreased the extent of ROS in the model. Unlike the sintered homogeneous models for which the live-oil-production rate remains reasonably constant during the lateral spreading phase of the VAPEX process, the vuggy-porosity models displayed a boost in the live-oil production rate when several vugs were being invaded by the solvent vapor. This behavior was more pronounced in the case of aligned vugs in which the vugs were closer to each other, and more vugs were invaded simultaneously compared with the case of a staggered-vug configuration. The enhanced pore-level mixing of solvent with bitumen, the improved petrophysical properties of the porous medium, and the flow communication of matrix with the vugs were found to enhance the live oil drainage towards the production well.

Occurrence, Structure and Mineral Phases of Nanoparticles in an Anthrosol

Soils contain various kinds of crystalline to amorphous solid particles with at least one dimension in the nanoscale (< 100 nm). These nanoparticles contribute greatly to dynamic soil processes such as soil genesis, trace element cycling, contaminant transport, and chemical reaction. The nano-sized fraction of an Anthrosol was obtained to determine the occurrence, chemical composition, structure, and mineral phases of nanoparticles using high-resolution transmission electron microscopy (HRTEM) equipped with an energy-dispersive X-ray spectroscopy. Selected area electron diffraction or the fast Fourier transform of high-resolution images was used in structural characterization of the nanoparticles with HRTEM. Two nanoscale mineral types, i.e., mineral nanoparticles and nanominerals, were observed in the Anthrosol. Mineral nanoparticles in soil included well crystalline aluminumsilicate nanosheets, nanorods, and nanoparticles. Nanosheets with a length of 120–150 nm and a width of about 10–20 nm were identified as chlorite/vermiculite series. The presence of clear lattice fringe spacing in HRTEM image of nanoparticles indicated that mineral nanoparticles had a relatively good crystallinity. The nanomineral ferrihydrite also existed in the Anthrosol. The HRTEM images and the particle size distribution histogram suggested that these ferrihydrite nanoparticles were quite homogeneous, and had a narrow size distribution range (1–7 nm) with a mean diameter of 3.6 ± 1.6 nm. Our HRTEM observation indicated that mineral nanoparticles and nanominerals were common and widely distributed in Anthrosols. HRTEM and selected area diffraction or lattice fringe spacing characterization provided further proofs to the structure of nanoparticles formed in soil.

Engineering liposomes of leaf extract of seabuckthorn (SBT) by supercritical carbon dioxide (SCCO2)-mediated process

Seabuckthorn (SBT; Hipphophae rhamnoides) leaf extract obtained by supercritical carbon dioxide (SCCO2) using ethanol as an entrainer, containing mainly flavanoids as bioactive principles with antioxidant and antibacterial properties, was used for the preparation of liposomes. Liposomes are promising drug carriers with sustained release because they can enhance the membrane penetration of drugs, deliver the entrapped drugs across cell membranes, and improve extract stability and bioavailability. The aim of the present study was to compare the two different methods of liposome production: the Bangham thin-film method and SCCO2 gas antisolvent method (SCCO2 GAS) for the incorporation of SBT leaf extract in terms of particle size, morphology, encapsulation efficiency, antioxidant activity, and thermal stability. Liposomes obtained with the thin-film method were multilamellar vesicles with average particle size (3,740 nm), encapsulation efficiency (14.60%), and particle-size range (1.57–6.0 µm), respectively. On the other hand, liposomes by the SCCO2 GAS method were nanosized (930 nm) with an improved encapsulation efficiency (28.42%) and narrow range of size distribution (0.48–1.07 µm), respectively. Further, the antioxidant activity of leaf extract of SBT was determined by the 2 diphenyl-1-picrylhydrazyl method and expressed as Trolox equivalents as well as of the intercalated extract in liposomes. The oxidative stability of SBT encapsulated in liposomes was again estimated using differential scanning calorimetry (DSC). Thermal-oxidative decomposition of the samples (i.e., pure liposomes and encapsulated extracts) and the modification of the main transition temperature for the lipid mixture and the splitting of the calorimetric peak in the presence of the antioxidants were also studied by DSC. After encapsulation in liposomes, antioxidant activity proved to be higher than those of the same extracts in pure form.

Optimization of catalytic, surface and magnetic properties of nanocrystalline manganese ferrite

Single-domain manganese ferrite nanoparticles have been synthesized with narrow particle size distribution using the combustion technique. Influence of fuel ratios on the as-prepared powders were characterized by XRD, SEM, VSM, N 2 adsorption at −196 °C and conversion of cyclohexene at 200–400 °C. Ratios of fuel to cations were maintained variously at 0.0, 0.67, 1.33 and 2.67. The fuel to cations ratio of 2.67 gives better yield in the formation of nanocrystalline Mn ferrite and single-domain particles with a narrow range of size distribution. Maximum magnetization and coercivity values of the investigated ferrite are also greater for the ratio of 2.67. These values measured at room temperature are found to be 68.58 emu/g and 62.57 Oe, respectively. The BET surface area of the investigated solids was found to decrease by increasing the ratio between fuel and cations due to increasing the flame temperature. However, this treatment resulted in a significant increase in catalytic activity of the as-synthesized solids. All solids investigated behaved as dehydrogenation catalysts. The change in fuel/cations ratios did not alter the mechanism of dehydrogenation of cyclohexene, but increased the concentration of active sites involved in the catalyzed reaction.

In vitro studies on liposomal amphotericin B obtained by supercritical carbon dioxide–mediated process

Nanotechnology in drug delivery is a rapidly expanding field. Nanosized liposomal preparations are already in use for efficient drug delivery with better therapeutic indices. Existing methods of liposome preparation are limited by problems of scale-up, difficulty in controlling size, and intercalation efficiency. Here we prepare amphotericin B–intercalated liposomes by a novel process where amphotericin B and purified phosphatidyl choline are solubilized in suitable solvent and precipitated in supercritical fluid carbon dioxide (known as a gas antisolvent technique), to obtain microsized particles that are subsequently introduced into a buffer solution. The morphology of liposomes was characterized through a phase-contrast microscope, and the particle size distribution studied by laser technique showed nanosize with a narrow range of size distribution (between 0.5 and 15 μm) and a higher intercalation efficiency. In vitro studies conducted using Aspergillus fumigatus (MTCC 870) strain proved to be efficient in the retardation of the growth of the organism.