Synthesis of WO3 in nanoscale with the usage of sucrose ester microemulsion and CTAB micelle solution

WO₃ nanoparticles were successfully prepared using first the low temperature hydrolysis method and second the chemical reaction method in water-in-oil sucrose ester microemulsion consisting of S1570, 1-butanol, tetradecane and aqueous phase. In this study WO₃ nanoparticles also were prepared using the CTAB micelle solution. The resultant WO₃ nanoparticles have been investigated with X-ray diffraction (XRD), transmission electron microscopy (TEM), variable pressure scanning electron microscope (SEM) equipped with energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). The shape and particles size of the resultant WO₃ nanoparticles from both methods in sucrose ester microemulsion show similar spherical shape and size range between 10 and 50 nm. The WO₃ nanoparticles prepared with the CTAB micelle solution show spherical shape with the size range average of 25-50 nm.     

A modern approach for controlled transdermal delivery of diflunisal: optimization and in vivo evaluation

The purpose of the present work was to elaborate an optimized transdermal therapeutic system for diflunisal. Selection of suitable ingredients was done via solubility and phase behavior studies. Composition of microemulsion (ME) systems consisting of butyl lactate, Brij^® 97, Transcutol^® and water was optimized using augmented simplex lattice mixture design. The independent variables selected were the percentages of butyl lactate, surfactant mixture and water. The dependent variables were refractive index, pH, conductivity, viscosity, drug solubility in the ME formulation and the ex vivo skin permeation flux. Mathematical equations and response surface plots were used to relate the dependent and independent variables. The statistical validity of the polynomials was established. Optimized formulation factors were selected by desirability approach. The optimized ME formulation was converted into gel using Carbomer^® 934. The microemulsion based gel (MBG) showed better spreadability and 5.07-fold increase in the transdermal flux than Carbomer^® 934 gel. The in vivo antihyperalgesia assay performed on mice showed significant reduction of the licking time in the treated group compared to the control group. This demonstrated the reliability of the simplex lattice statistical design for predicting optimum ME formulation. The developed MBG proved its in vivo efficiency for transdermal delivery of diflunisal.     

Microemulsion for simultaneous transdermal delivery of benzocaine and indomethacin: in vitro and in vivo evaluation

This study investigated simultaneous transdermal delivery of indomethacin and benzocaine from microemulsion. Eucalyptus oil based microemulsion was used with Tween 80 and ethanol being employed as surfactant and cosurfactant, respectively. A microemulsion formulation comprising eucalyptus oil, polyoxyethylene sorbitan momooleate (Tween 80), ethanol and water (20:30:30:20) was selected. Indomethacin (1% w/w) and benzocaine (20% w/w) were incorporated separately or combined into this formulation before in vitro and in vivo evaluation. Application of indomethacin microemulsion enhanced the transdermal flux and reduced the lag time compared to saturated aqueous control. The same trend was evident for benzocaine microemulsion. Simultaneous application of the two drugs in microemulsion provided similar enhancement pattern. The in vivo evaluation employed the pinprick method and revealed rapid anesthesia after application of benzocaine microemulsion with the onset being 10?min and the action lasting for 50?min. For indomethacin microemulsion, the analgesic effect was recorded after 34.5?min and lasted for 70.5?min. Simultaneous application of benzocaine and indomethacin provided synergistic effect. The onset of action was achieved after 10?min and lasted for 95?min. The study highlighted the potential of microemulsion formulation in simultaneous transdermal delivery of two drugs.     

Ceramide-2 nanovesicles for effective transdermal delivery: development,characterization and pharmacokinetic evaluation

Context: The vesicles based on skin lipid have a drug localization effect and its main lipid, ceramide provides protective and regenerative effects while oleic acid (OA) is a penetration enhancer, however, it causes slight irritation, so we have formulated formulation incorporating both of these to develop a transdermal formulation for better permeation.

Objective: Present study investigated the preparation and characterization of physicochemical properties and permeation of nanovesicles of ceramide-2 containing OA and palmitic acid (PA) respectively and a commercial gel.

Materials and methods: The vesicles were made using ceramide 2, cholesterol (Chol), cholesteryl sulfate (CS) and OA or PA, respectively, using film hydration method. The vesicles were characterized for physicochemical properties, ex vivo permeation using human skin and pharmacokinetic parameters and anti-inflammatory activity in rats.

Results: The vesicles showed size at 102–125?nm while PDI was 0.11–0.13 and negative zeta potential. OV-3 showed highest entrapment efficiency. The drug fluxes were 92.02 and 8.920?μg/cm²/h, respectively, for OV-3 and PV-1. The C_max were 7.91 and 4.01?μg/ml at 4 and 6?h for OV-3 (2.5?mg) and PV-1 (10?mg), respectively. OV-3 and PV-1 showed 98.8% and 77.36% edema inhibition, respectively, at 3?h.

Discussion: Both formulations showed similar physical parameters and different permeation since OA get incorporated in vesicles and increases its permeability and ceramide makes sure that vesicles can rapidly traverse the stratum corneum.

Conclusion: OV-3 containing 3% OA showed optimum physical parameters and good permeation with maximum anti-inflammatory activity.     

Evidence for supercooling across a vortex-matter phase transition: studies on CeRU2 and Bi2Sr2CaCu2O8

We present DC magnetization data indicating a first-order phase transition in the vortex state of CeRu₂, with the higher entropy phase exhibiting enhanced pinning. Minor hysteresis loops show evidence of supercooling of the higher entropy phase as the phase boundary is crossed both isothermally as well as at constant field. These features are shown to be absent across the Bragg-glass to vortex-glass transition in Bi₂Sr₂CaCu₂O₈. The supercooling is more persistent in the constant field case.     

Microemulsion loaded hydrogel as a promising vehicle for dermal delivery of the antifungal sertaconazole: design,optimization and ex vivo evaluation

The purpose of the present study was to develop and optimize sertaconazole microemulsion-loaded hydrogel (STZ ME G) to enhance the dermal delivery and skin retention of the drug. Following screening of various oils for maximum drug solubility, 12 pseudoternary phase diagrams were constructed using oils (Peceol^®, Capryol^® 90), surfactants (Tween^® 80, Cremophor^® EL), a cosurfactant (Transcutol^® P) and water. A 2¹ × 3¹ × 2¹ × 3¹ full factorial design was employed to optimize a ME of desirable characteristics. The MEs were formulated by varying the oil type, oil concentration, surfactant type and surfactant: cosurfactant ratio. Optimized ME formulae F22 [5% Peceol^®, 55% Tween^® 80: Transcutol^® (1:2), 40% water] and F31 [5% Peceol^®, 55% Cremophor^® EL: Transcutol^® (1:2), 40% water] acquired mean droplet size of 75.21 and 8.68?nm, and zeta potential of 34.65 and 24.05?mV, respectively. Since F22 showed higher STZ skin retention during ex vivo studies (686.47?μg/cm²) than F31 (338.11?μg/cm²); hence it was incorporated in 0.5% Carbopol 934 gel to augment STZ skin retention capability. STZ ME G exhibited higher STZ skin retention (1086.1?μg/cm²) than the marketed product “Dermofix^® cream” (270.3?μg/cm²). The antimycotic activity against C.albicans revealed increased zones of inhibition for F22 and STZ ME G (35.75 and 30.5?mm, respectively) compared to Dermofix^® cream (26?mm). No histopathological changes were observed following topical application of STZ ME G on rats’ skin (n?=?9). Overall, the obtained results confirmed that the fabricated formulation could be a promising vehicle for the dermal delivery of STZ.     

A novel mixed polymeric micelle for co-delivery of paclitaxel and retinoic acid and overcoming multidrug resistance: synthesis,characterization, cytotoxicity,and pharmacokinetic evaluation

In the current study, retinoic acid (RA) was conjugated to Pluronic F127 (PF127) through an esterification process. Mixed micelles were formed with tocopheryl polyethylene glycol 1000 (TPGS) for co-delivery of paclitaxel (PTX) and RA to the cancer cells. Mixed micelles of RA-PF127 and TPGS in different weight ratios (10:0, 7:3, 5:5, 3:7, 0:10 w/w) were prepared and physicochemical properties including, particle size, zeta potential, critical micelle concentration (CMC), drug loading content, entrapment efficiency, drug release, cellular uptake and in vitro cytotoxicity, were investigated in details. Furthermore, the pharmacokinetics of PTX-loaded optimized mixed micelles were evaluated in Sprague-Dawley rats and compared with Stragen^® (PTX in Cremophor EL^®). Particle sizes and zeta potentials of the drug-loaded micelles were in the range of 102.6–223.5?nm and ?5.3 to ?9.6?mV, respectively. The 7:3 and 5:5 micellar combinations had lower CMC values (0.034–0.042?mg/mL) than 0:10 (0.124?mg/mL). The entrapment efficiencies of 10:0, 7:3, and 5:5 were 53.4?±?9.3%, 61.3?±?0.5%, and 78.7?±?1.66%, respectively. The release rates of PTX from 7:3 and 5:5 mixed micelles were significantly slower than other formulations. Cytotoxicity assay demonstrated increased cytotoxic activity of PTX-loaded mixed micelles compared to free PTX. The V_d and t_1/2ß of PTX-loaded RA-PF127/TPGS (7:3) were increased by 2.61- and 1.27-fold, respectively, while the plasma area under the curve (AUC) of the micelles was 2.03-fold lower than those of Stragen^®. Therefore, these novel mixed micelles could be effectively used for delivery of PTX and RA to the cancer cells. Moreover, TPGS as part of micelle composition could enhance the therapeutic effect of PTX and reduce side effects.     

Oxidation of triclosan by ferrate: reaction kinetics, products identification and toxicity evaluation

The Crystal Violet (CV) dye represented one of the major triphenylmethane dyes used in textile-processing and some other industrial processes. Various metals doped titanium dioxide (TiO(2)) photocatalysts have been studied intensively for the photodegradation of dye in wastewater treatment. In order to understand the mechanistic detail of the metal dosage on the activities enhancement of the TiO(2) based photocatalyst, this study investigated the CV photodegradation reactions under UV light irradiation using a Pt modified TiO(2) photocatalyst. The results showed that Pt-TiO(2) with 5.8% (W/W) Pt dosage yielded optimum photocatalytic activity. Also the effect of pH value on the CV degradation was well assessed for their product distributions. The degradation products and intermediates were separated and characterized by HPLC-ESI-MS and GC-MS techniques. The results indicated that both the N-de-methylation reaction and the oxidative cleavage reaction of conjugated chromophore structure occurred, but with significantly different intermediates distribution implying that Pt doped TiO(2) facilitate different degradation pathways compared to the P25-TiO(2) system.     

Optimization and evaluation of microwave-assisted synthesis of magnetite as a carrier for targeted drug delivery system

ABSTRACT

The present research work is a novel cost-effective method for synthesis of magnetite. Magnetite is a carrier which is used in the targeted drug delivery system. The conventional methods of preparation of magnetite take around 6–7 h for the completion of reaction; moreover, the particle size of magnetite which we get by the conventional methods is above 5 µm, so the present work aims at preparing magnetite with microwave assistance which has found to reduce reaction time with particle size obtained below 5 µm. The aim of this study was to optimize magnetite synthesis using 2³ factorial design by Design-Expert software. Magnetites were synthesized using oxidation of ferrous sulfate. In the next step, the effects of different variables on particle size are studied, including the stirring speed, microwave power (W), and stirring time. Based on the type and the variables studied, eight formulations were designed using factorial design method, and were then prepared, and their particle size was determined. Finally, selected magnetite syntheses were evaluated from the viewpoints of scanning electron microscopy (SEM) and x-ray diffraction (XRD). Results revealed that magnetite obtained from the solutions generated Design-Expert software could be selected as the best and optimized formulations due to their lowest particle size.     

Ca4REO(BO3)3 crystals for green and blue microchip laser generation: from crystal growth to laser and nonlinear optical properties

We have taken advantage of congruent melting behavior of the nonlinear rare-earth oxoborate Ca₄REO(BO₃)₃ family to perfect a process of collective fabrication of self-frequency doubling microchip laser based on Nd:GdCOB (Ca₄Gd_1−xNd_xO(BO₃)₃) crystals. The process goes from Czochralski boule to 1 × 3 mm² chips perfectly oriented (better than 0.1°) to the phase matching direction (θ=90°, φ=46°) in the XY principal plane, with dielectric mirrors directly deposited on both faces of the chips. 20 mW of self-frequency doubling output power at 530 nm was performed under 800 mW of diode laser as incident pump power at 812 nm. In addition, new compositions from the solid solution Ca₄Gd_1−xY_xO(BO₃)₃ (Gd_1−xY_xCOB) (x=0.13, 0.16, 0.44) have been grown by the Czochralski pulling method, in order to achieve noncritical phase matching (NCPM) second harmonic generation of ⁴F_3/2 → ⁴I_9/2 Nd³⁺ doped laser hosts. Three types of laser wavelengths have been chosen: Nd:YAP (YAlO₃) at 930 nm, Nd:YAG (Y₃Al₅O₁₂) at 946 nm, and Nd:ASL (Nd_ySr_1−x La_x−yMg_x Al_12−xO₁₉) at 900 nm. Angular acceptance measurements of these three types of compositions present very large values, compared to pure GdCOB or YCOB oriented in critical phase matching configurations.     

Capecitabine lipid nanoparticles for anti-colon cancer activity in 1,2-dimethylhydrazine-induced colon cancer: preparation,cytotoxic, pharmacokinetic,and pathological evaluation

The cornerstone of this investigation is to determine the pharmacokinetic and histopathological behavior of solid lipid nanoparticles of capecitabine (CB-SLNs) in 1,2-dimethylhydrazine (DMH) induced colon cancer. The nanoparticles were prepared by microemulsion method. CB-SLNs were characterized for an optimal system. The cytotoxicity of CB-SLNs was evaluated by using MTT assay method. Further, pharmacokinetic and histopathological behavior of SLNs were studied in DMH induced colon cancer rats. The optimized nanoparticles have the particle size, zeta potential, and entrapment efficiency of 145.6?±?3.6?nm, ?26.9?±?2.7?mV, and 88.33?±?3.74%, respectively. Particles of CB were nearly spherical in shape and converted to amorphous form revealed by SEM and DSC, XRD studies. The nanoparticles showed dose-dependent cytotoxicity activity from 10 to 125?µg/mL compared with suspension. Pharmacokinetic studies revealed that 2.7-folds enhancement in the oral bioavailability and in aberrant crypt foci number, apoptotic index comparison with suspension formulation.     

In2O3 nanowires for gas sensors: morphology and sensing characterisation

Thin and densely packed In₂O₃ nanowires have been synthesised on alumina substrates via transport and condensation method, starting from nanoparticles of indium or palladium as catalysts for the condensation process. Indium catalyst promoted wires growth according to vapour-solid (VS) mechanism, while palladium catalyst leads to wires formation based on vapour-liquid-solid (VLS) condensation. Electron microscopy and related diffraction analysis demonstrated that the wires are monocrystalline, with atomically sharp termination of the lateral sides, and are free from extended defects. The sensing properties of nanowires bundles have been tested to acetone using the flow through technique in the temperature range between 100 and 500 °C.     

Optimization of n nc-Si:H and a-SiNx:H layers for their application in nc-Si:H TFT

The n-type doped silicon thin films were deposited by plasma enhanced chemical vapor deposition (PECVD) technique at high and low H₂ dilutions. High H₂ dilution resulted in n⁺ nanocrystalline silicon films (n⁺ nc-Si:H) with the lower resistivity (ρ ∼0.7 Ω cm) compared to that of doped amorphous silicon films (∼900 Ω cm) grown at low H₂ dilution. The change of the lateral ρ of n⁺ nc-Si:H films was measured by reducing the film thickness via gradual reactive ion etching. The ρ values rise below a critical film thickness, indicating the presence of the disordered and less conductive incubation layer. The 45 nm thick n⁺ nc-Si:H films were deposited in the nc-Si:H thin film transistor (TFT) at different RF powers, and the optimum RF power for the lowest resistivity (∼92 Ω cm) and incubation layer was determined. On the other hand, several deposition parameters of PECVD grown amorphous silicon nitride (a-SiN_x:H) thin films were changed to optimize low leakage current through the TFT gate dielectric. Increase in NH₃/SiH₄ gas flow ratio was found to improve the insulating property and to change the optical/structural characteristics of a-SiN_x:H film. Having lowest leakage currents, two a-SiN_x:H films with NH₃/SiH₄ ratios of ∼19 and ∼28 were used as a gate dielectric in nc-Si:H TFTs. The TFT deposited with the NH₃/SiH₄∼19 ratio showed higher device performance than the TFT containing a-SiN_x:H with the NH₃/SiH₄∼28 ratio. This was correlated with the N−H/Si−H bond concentration ratio optimized for the TFT application.     

Preparation and evaluation of charged solid lipid nanoparticles of tetrandrine for ocular drug delivery system: pharmacokinetics,cytotoxicity and cellular uptake studies

In this study, tetrandrine-loaded cationic solid lipid nanoparticles (TET-CNP) and solid lipid nanoparticles (TET-NP) were prepared by the emulsion evaporation-solidification at low temperature method. The particle size, zeta potential, and entrapment efficiency of TET-CNP and TET-NP were characterized. The results showed that the TET-CNP and TET-NP had average diameters of (15.29?±?1.34) nm and (18.77?±?1.23) nm with zeta potentials of (5.11?±?1.03) mV and (?8.71?±??1.23) mV and entrapment efficiencies of (94.1?±?2.37)% and (95.6?±?2.43)%, respectively. In vitro release studies indicated that the TET-CNP and TET-NP retained the drug entity better than tetrandrine ophthalmic solutions (TET-SOL). In the pharmacokinetics studies, the AUC values of TET-CNP and TET-NP were 1.96-fold and 2.00-fold higher than that of TET-SOL (?p?C_max values of TET-CNP and TET-NP were 2.45-fold and 2.53-fold higher than that of the TET-SOL (p?相似文献   

Synthesis and luminescent properties of SrAl2O4:Eu green-emitting phosphor for white LEDs

SrAl₂O₄:Eu²⁺ phosphor was prepared by a solid-state reaction in CO-reductive atmosphere. X-ray powder diffraction (XRD) analysis confirmed the formation of SrAl₂O₄:Eu²⁺. Field-emission scanning electron-microscopy (FE-SEM) observation indicated that the microstructure of the phosphor consisted of irregular fine grains with an average size of about 7–8 μm. Photoluminescence measurements showed that the phosphor can be efficiently excited by UV–visible light from 350 to 430 nm, and exhibited bright green emission peaked at about 516 nm. Bright green LEDs were fabricated by incorporating the phosphor with an InGaN-based UV chip. All the characteristics indicated that SrAl₂O₄:Eu²⁺ is a good candidate phosphor applied in white LEDs.     

Fracture toughness and reliability in high-temperature structural ceramics and composites: Prospects and challenges for the 21st century

The importance of high fracture toughness and reliability in Si₃N₄, and SiC-based structural ceramics and ceramic matrix composites is reviewed. The potential of these ceramics and ceramic matrix composites for high temperature applications in defence and aerospace applications such as gas turbine engines, radomes, and other energy conversion hardware have been well recognized. Numerous investigations were pursued to improve fracture toughness and reliability by incorporating various reinforcements such as particulate-, whisker-, and continuous fibre into Si₃N₄ and SiC matrices. All toughening mechanisms, e.g. crack deflection, crack branching, crack bridging, etc essentially redistribute stresses at the crack tip and increase the energy needed to propagate a crack through the composite material, thereby resulting in improved fracture toughness and reliability. Because of flaw insensitivity, continuous fibre reinforced ceramic composite (CFCC) was found to have the highest potential for higher operating temperature and longer service conditions. However, the ceramic fibres should display sufficient high temperature strength and creep resistance at service temperatures above 1000°C. The greatest challenge to date is the development of high quality ceramic fibres with associate coatings able to maintain their high strength in oxidizing environment at high temperature. In the area of processing, critical issues are preparation of optimum matrix precursors, precursor infiltration into fibre array, and matrix densification at a temperature, where grain crystallization and fibre degradation do not occur. A broad scope of effort is required for improved processing and properties with a better understanding of all candidate composite systems.     

Er:YAl3(BO3)4 glassy thin films from polymeric precursor and sol-gel methods: Waveguides for integrated optics

This paper presents the characterization of single-mode waveguides for 980 and 1550 nm wavelengths. High quality planar waveguide structure was fabricated from Y_1 − xEr_xAl₃(BO₃)₄ multilayer thin films with x = 0.02, 0.05, 0.1, 0.3, and 0.5, prepared through the polymeric precursor and sol-gel methods using spin-coating. The propagation losses of the planar waveguides varying from 0.63 to 0.88 dB/cm were measured at 632.8 and 1550 nm. The photoluminescence spectra and radiative lifetimes of the Er^{3+ 4}I_13/2 energy level were measured in waveguiding geometry. For most samples the photoluminescence decay was single exponential with lifetimes in between 640 μs and 200 μs, depending on the erbium concentration and synthesis method. These results indicate that Er doped YAl₃(BO₃)₄ compounds are promising for low loss waveguides.     

Pulse-shape analysis of Cs2LiYCl6:Ce scintillator for neutron and gamma-ray discrimination

Cs₂LiYCl₆:Ce (CLYC) is one of the most promising new scintillators for detecting both neutrons and gamma-rays. Its neutron and gamma-ray discrimination capability using pulse-shape analysis has drawn much attention, and there is significant interest in its use in field applications. For such applications, compact and low-power readout electronics capable of exploiting the pulse-shape discrimination (PSD) capabilities of CLYC will be essential. A readout system centered around a PSD-capable application specific integrated circuit (ASIC) that is well-suited for use with CLYC has been characterized, tested, and validated. As part of this study, automated analysis of CLYC data collected with a fast waveform digitizer extracted optimized charge integration windows for PSD. Additionally, several different CLYC samples were studied in order to gain understanding of the dependance of pulse shapes on parameters such as crystal size, ⁶Li enrichment level, crystal packaging, and choice of PMT. Extremely good PSD performance was obtained from CLYC scintillator and the ASIC-based readout system.     

Chitosan nanoparticles for the oral delivery of tenofovir disoproxil fumarate: formulation optimization,characterization and ex vivo and in vivo evaluation for uptake mechanism in rats

Objective: Design chitosan based nanoparticles for tenofovir disoproxil fumarate (TDF) with the purpose of enhancing its oral absorption.

Significance: TDF is a prodrug that has limited intestinal absorption because of its susceptibility to gut wall esterases. Hence, design of chitosan based polymeric novel nanocarrier systems can protect TDF from getting metabolized and also enhance the oral absorption.

Methods: The nanoparticles were prepared using the ionic gelation technique. The factors impacting the particle size and entrapment efficiency of the nanoparticles were evaluated using design of experiments approach. The optimized nanoparticles were characterized and evaluated for their ability to protect TDF from esterase metabolism. The nanoparticles were then studied for the involvement of active transport in their uptake during the oral absorption process. Further, in vivo pharmacokinetic studies were carried out for the designed nanoparticles.

Results: The application of design of experiments in the optimization process was useful to determine the critical parameters and evaluate their interaction effects. The optimized nanoparticles had a particle size of 156?±?5?nm with an entrapment efficiency of 48.2?±?1%. The nanoparticles were well characterized and provided metabolic protection for TDF in the presence of intestinal esterases. The nanoparticles were able to increase the AUC of tenofovir by 380%. The active uptake mechanisms mainly involving clathrin-mediated uptake played a key role in increasing the oral absorption of tenofovir.

Conclusions: These results show the ability of the designed chitosan based nanoparticles in enhancing the oral absorption of TDF along the oral route by utilizing the active endocytic uptake pathways.     

Improving the angular color uniformity and the lumen output for multi-chip white LED lamps by green Ce0.67Tb0.33MgAl11O19:Ce,Tb phosphor

In this paper, we propose and discuss how to enhance the color uniformity and the lumen output of multi-chip white LED lamps (MCW-LEDs). This can be done by combining the green Ce_0.67Tb_0.33MgAl₁₁O₁₉:Ce,Tb phosphor (CeTb) and phosphor compounding. We find that the proposed method can have a significant effect on MCW-LEDs performance. Through simulation results, it is confirmed that the color uniformity and the lumen output of MCW-LEDs with average correlated color temperatures of 7000 and 8500 K grow with the concentration of CeTb, while the color rendering ability decreases. With proper choice of CeTb concentration, good performance of MCW-LEDs can be obtained.